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Het plante kenmerkende DNA-genome van mekaar soos mense doen?

Het plante kenmerkende DNA-genome van mekaar soos mense doen?


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Kan presies dieselfde plantspesies 'n ander genoom hê as ander van dieselfde presiese spesies wat naby of in 'n ander plek/land groei, ens.?

Kan 'n blaar opgespoor word na die presiese plant gebaseer op DNS as ons DNS van die "ouer" plant van die blaar gegee sou word, en twee toetsplante se DNS van presies dieselfde spesie?


Kort antwoord: Ja!

Nou vir die langer antwoord. Ja, hulle het oor die algemeen afsonderlike gene, maar wat jy as verskillende plante kan sien, kan ook soms klone wees. Byvoorbeeld, Bewende Aspenbome wat algemeen in klonale kolonies groei.

As jy 'n massiewe databasis van genetiese materiaal van plante gehad het, sou jy dit kon opspoor. Jy kan dalk deur steekproefneming uit te werk waar 'n steekproef geografies geleë was.


Ons moet plante wat deur seksuele voortplanting repliseer, onderskei van dié wat ongeslagtelik voortplant.

As gevolg van die hoër rekombinasietempo in seksuele voortplanting behoort dit maklik te wees om jou plant te vind waarmee die blaar ooreenstem. Omdat jy baie enkelnukleotied polimorfismes kan sien en dalk ander veranderinge in die DNA wat uniek is aan die plant wie se blaar jy gevind het.

As jou plantspesie deur vegetatiewe voortplanting voortplant, kan dit moeiliker wees omdat jy nie baie DNA-veranderinge kan vind wat jou plant uniek maak nie. Maar aangesien daar 'n paar mutasies in DNA van vegetatief voortplantende plante is (sien hier en hier), moet jy waarskynlik probeer om hulle te vind.


Wat beteken die feit dat ons 95 persent van ons gene met die sjimpansee deel? En hoe is hierdie getal afgelei?

Daar is 'n aansienlike hoeveelheid bewyse wat die idee ondersteun dat die sjimpansee die naaste genetiese familielid van mense is. Dit is eers deur 'n groot aantal studies bepaal, waarvan sommige genomiese DNA-hibridisasie gebruik het om die vlak van volgorde-wanpassings op te spoor, asook ontledings van individuele proteïenmolekules. Hierdie vroeë bevindings het voorgestel dat sjimpansees en mense tipies rye kan hê wat slegs met ongeveer 1 persent van mekaar verskil.

Ons het nou groot streke van die sjimpansee-genoom volledig in volgorde en kan dit vergelyk met menslike volgordes. Die meeste studies dui daarop dat wanneer genomiese streke tussen sjimpansees en mense vergelyk word, hulle ongeveer 98,5 persent volgorde-identiteit deel. Die werklike verwantskap hang af van watter tipe rye vergelyk word en die grootte van die vergelykingseenheid. 'n Verslag wat in 2002 in die Proceedings of the National Academy of Sciences gepubliseer is, het voorgestel dat onder die strengste belynings, die wedstryd in die algemeen slegs 95 persent ooreenkoms sou wees. Dit het voortgespruit uit die navorsers wat veranderinge wat klein invoegings en delesies van basisse behels anders behandel het as wat vorige navorsers oor 'n baie groot streek gedoen het. 'n Paar vrae bly steeds oor of die sjimpansee-genoomvolgordedata op hierdie stadium van hoë gehalte is vir betroubare vergelyking. Oor die algemeen is die algehele gevolgtrekking egter dat die meeste gene ongeveer 98,5 persent ooreenkoms sal deel. Die werklike proteïenvolgorde wat deur hierdie gene gekodeer word, sal dan tipies effens meer aan mekaar ooreenstem, omdat baie van die mutasies in die DNA "stil" is en nie in die proteïenvolgorde weerspieël word nie.

Gegewe die baie sterk ooreenkoms tussen die sjimpansee en menslike genome, wonder baie mense hoe ons so anders kan wees. Op hierdie stadium was daar net 'n paar geïsoleerde voorbeelde van gene wat funksioneel in sjimpansees voorkom, maar nie in mense nie, en omgekeerd. Dus, sjimpansees en mense kan soveel as 99,9 persent van dieselfde gene deel, met die meeste van daardie gene wat 99 persent soortgelyk is in hul volgorde. Chromosome vertoon ook nie groot strukturele verskille nie. Alhoewel daar 'n aantal klein chromosomale veranderinge is wat die volgorde van gene op streke van daardie chromosome herrangskik, word gedink dat die meeste hiervan geenfunksie onveranderd laat. Dit lyk waarskynlik dat die verskille tussen menslike en sjimpansee-fenotipes meer afhang van subtiele regulatoriese veranderinge as van die teenwoordigheid van verskillende gene. Dit kan byvoorbeeld wees dat daar veranderinge in sommige gene is wat die hoeveelheid proteïen wat deur daardie geen geproduseer word, verander op verskillende stadiums in die ontwikkeling van 'n sjimpansee teenoor 'n mens. Alternatiewelik kan daar klein veranderinge aan die strukture van die proteïene wees (vanaf die 1 persent divergensie) wat veranderinge veroorsaak in hoe hulle met ander sellulêre komponente in wisselwerking tree en dus die weë waarin hulle betrokke is subtiel verander. Op hierdie stadium weet ons nie watter tipe veranderinge verantwoordelik is vir die relatief groot verskille tussen sjimpansees en mense nie.

Dit is opmerklik dat individuele mense oor die algemeen geneties met ongeveer 0,1 persent verskil. Dus verskil sjimpansees gemiddeld ongeveer 15 keer meer van mense as wat mense van mekaar verskil. Die 0,1 persent menslike divergensie lei beslis tot beduidende variasie in fisiese voorkoms en eienskappe tussen verskillende mense. Daarom moet ons miskien nie so verbaas wees dat sjimpansees 98,5 persent aan mense verwant kan wees nie. Relatief klein genetiese veranderinge kan groot fenotipiese veranderinge veroorsaak.


Internasionale genoomspan ontsyfer genetiese instruksies vir 'n volledige dier

BETHESDA, Md. - Alhoewel verskeie van hulle op die kop van 'n speld sal pas, is die klein rondewurm, bekend onder sy wetenskaplike naam as Caenorhabditis elegans, het dit vandag groot gemaak toe Human Genome Project-navorsers in die Verenigde State en Groot-Brittanje aangekondig het dat hulle die dier se 97 miljoen basisgenoom in volgorde bepaal het. Dit is die eerste keer dat wetenskaplikes die instruksies vir 'n volledige dier uitgespel het, wat, soos mense, 'n senuweestelsel het, kos verteer en seks het. Die werk, wat by die Washington University School of Medicine in St. Louis en die Sanger-sentrum in Cambridge, Engeland uitgevoer is, word in die uitgawe van 11 Desember van die joernaal gepubliseer. Wetenskap.

"Dit is 'n geweldige verblydende oomblik en meer van 'n begin as 'n einde," sê Robert Waterston, leier van die St. Louis-groep wat agt jaar gewerk het om die werk te voltooi. "Ons het bioloë voorsien van 'n kragtige nuwe hulpmiddel om mee te eksperimenteer en te leer hoe genome funksioneer. Ons sal vrae kan vra en beantwoord waaraan ons nooit eers kon dink nie."

John Sulston, wat die Mediese Navorsingsraad-groep by die Sanger-sentrum gelei het, het gesê: "Toe ek en Bob in die middel van die 1980's genetika in die wurm begin studeer het, het dit duidelik geword dat die beste manier om die gene waarna ons gesoek het te vind, was om volgorde van die hele genoom. Seker genoeg, wat ons nou in daardie genoom gevind het, oortref verreweg wat ons kon dink."

Alhoewel die meeste mense nog nooit van die kort wurm met die lang naam gehoor het nie - die dier meet ongeveer 1 millimeter van punt tot punt ongeveer 40 van hulle sal die woorde oorskry Caenorhabditis elegans - hulle leef daagliks onder die voete. C. elegans, soos wetenskaplikes hulle noem, bewoon die grond in gematigde streke. ’n Handvol grond kan duisende wurms bevat wat deur waterdruppels wat tussen gronddeeltjies vasgevang is, gly. Sommige van sy aalwurmneefs is parasiete, maar vuilverspreidend C. elegans verkies 'n goedaardige bestaan ​​onder verrottende plante. Terug by die laboratorium leef die wesens in petriskottels op 'n bestendige dieet van die bakterie E coli.

Alhoewel dit 'n relatief ver tak op die evolusionêre boom beslaan, C. elegans deel nietemin baie ooreenkomste met mense, wat dit 'n belangrike organisme maak om studies te doen wat ooreenstem met menslike biologie. Anders as die veel kleiner mikrobes wat tot dusver in volgorde geplaas is, C. elegans begin lewe as 'n enkele, bevrugte sel en ondergaan 'n reeks seldelings soos dit tot 'n volwasse dier groei. Tydens die proses vorm komplekse weefsels en orgaanstelsels. Sowat 300 van die 959 selle van die volwasse wurm, byvoorbeeld, vorm 'n senuweestelsel wat reuk, smaak en reageer op temperatuur en aanraking kan opspoor. ’n Spysverteringsbuis loop oor die lengte van die wurm se liggaam. Om 'n seksmaat te vind is nooit 'n probleem nie, aangesien die meeste lede van die spesie beide manlike en vroulike geslagsorgane dra en hulself bevrug. Omdat die dier letterlik deursigtig is, kan sy liggaamlike gebeure onder 'n mikroskoop waargeneem word.

In sy lewensduur van twee tot drie weke, C. elegans voer baie van dieselfde prosesse uit wat mense doen: hulle ondergaan embrioniese ontwikkeling, eet, reproduseer, word oud en sterf. Navorsers het hulle dus veral nuttig gevind om vroeë ontwikkeling, neurobiologie en veroudering te bestudeer. Trouens, elke verband in die wurm se senuweestelsel is gekarteer, en die afkoms van elke sel in die volwasse dier se liggaam is nagespoor vanaf die oomblik van bevrugting. Die wurm se genetiese materiaal is op ses chromosome verpak. Volgens die Wetenskap verslag het ontleding van die wurm se genoom 19 099 proteïenkoderende gene aan die lig gebring - ongeveer een elke 5 000 DNA-basisse - en 800 of so gene wat ander funksies het. Dit is 'n paar keer die aantal gene wat deur klassieke genetika-eksperimente voorspel is. Ongeveer 40 persent van die 19 099 gene stem ooreen met dié van ander organismes, insluitend mense. Die ander 60 persent verteenwoordig nuwe raaisels wat op verduideliking wag.

Die chromosome self lyk meer soos menslike chromosome as dié van bakterieë of gis. Hulle bevat groot hoeveelhede herhaalde DNA wat nie proteïene kodeer nie, maar waarskynlik 'n rol speel in chromosoomfunksie of die organisering van gene of die regulering van hul aktiwiteit.

Vir byna 'n dekade het spanne aan beide kante van die Atlantiese Oseaan miljoene stukkies wurm-DNA gesny en op volgorde gerangskik, dit in lang stukke gedokumenteerde volgorde geplak en dit in 'n publieke databasis gestort. Stadig en met slegs 'n paar navorsers aanvanklik, het die projek na ongeveer 1993 in grootte, uitset en befondsing gegroei. Behalwe daaglikse e-poskontak, het die hele laboratoriumpersoneel jaarliks ​​heen en weer van St. Louis na Cambridge gereis totdat hul getalle te veel geword het. puik. Die groepleiers, Waterston en Sulston, het later hul toevlug tot gereelde Sondag-telefoonoproepe gewend. "Gelukkig," sê Waterston, "is John 'n naguil."

"Wetenskaplikes is veronderstel om eensame mense te wees, maar dit was regtig pret en baie lonend om saam met die talentvolle klomp mense wat ons aan beide kante van die Atlantiese Oseaan het," het Waterston gesê, "net om te kyk hoe die kombinasie van verstand en talente gaan na werk aan hierdie probleem."

Die twee spanne het inligting nie net met mekaar gedeel nie, maar met enige wetenskaplike wat dit wou hê. “Die toewyding van hierdie groepe om hul volgordedata reg van die begin af aan die navorsingsgemeenskap beskikbaar te stel, is bewonderenswaardig,” sê Francis Collins, direkteur van die Nasionale Menslike Genoom Navorsingsinstituut, 'n hoofspeler in die Menslike Genoomprojek. "Dit tipeer die gees van die Menslike Genoomprojek en is presies hoe ons beplan om ons volgordebepalingsprogram op die menslike genoom en ander modelorganismes te bedryf."

In onlangse jare, terwyl die wurmvolgorders hul pas getref het, het 'n paar dosyn opeenvolgingsmasjiene die hele dag en die meeste dae van die week gegons. Die eerste skof het volgens Waterston om 05:30 by die laboratorium aangekom om die vorige nag se lopie af te laai. Die laaste skof, wat die laboratorium omstreeks middernag verlaat het, het die masjiene tot dagbreek laat gons. Altesaam 2 miljoen "lees" het die wurmvolgorde uitgespel, 500 basisse op 'n slag.

Vir die Human Genome Project (HGP) is die voltooiing van die wurmgenoom nog 'n sukses in 'n reeks vinnige mylpale. Onlangs het die projek aangekondig dat dit sy poging om die 3 miljard basispaar, menslike genoomvolgorde twee jaar voor die tyd te voltooi, sal bespoedig, deels omdat die wurmvolgorders sulke suksesvolle metodes vir komplekse genome daargestel het. “Bob en John se werk het ons baie vertroue gegee dat ons die menslike volgorde gouer as wat beplan is gedoen kan kry,” het Collins gesê. "Nou is ons meer gretig as ooit om die instruksieboek vir 'n mens te kry."

Die wurmgroep by die Genome Sequencing Centre in St Louis word gefinansier deur die National Human Genome Research Institute, deel van die National Institutes of Health, die federale regering se primêre biomediese navorsingsinstelling. Die wurmgroep by Sanger-sentrum word deur die Mediese Navorsingsraad van Groot-Brittanje befonds.

"Genoomvolgorde van die nematode C. elegans: 'n Platform vir die ondersoek van biologie."Die Genome Sequencing Consortium. Wetenskap 282: 2012-2021, 1998.


Ooreenkomste tussen mense en sjimpansees

Sjimpansees is geneties baie na aan mense, en in werklikheid deel sjimpansees ongeveer 98,6% van hul DNA. Ons deel meer van ons DNA met sjimpansees as met ape of verskillende spanne, en selfs met verskillende groot ape!

Albei van ons speel, het ingewikkelde gevoelens en intelligensie, en werklik verwante fisiese strukture om ooreenkomste tussen mense en sjimpansees te identifiseer.

Sedert die primate is geassosieer, hulle’re geneties intensief gekorreleer met mekaar. Menslike DNA is, in gemeen, 96% soortgelyk aan die DNA van ons mees afgeleë primaatverhoudings, en feitlik 99% soortgelyk aan ons naaste verwantskappe, sjimpansees en bonobo's.

Terwyl die genetiese onderskeid tussen bepaalde menseregte nou baie minimum is – ongeveer 0,1%, gemiddeld – dui navorsing van die identiese kenmerke van die sjimpansee-genoom 'n onderskeid van ongeveer 1,2% aan.

Die bonobo (Pan paniscus), wat die naaste neef van sjimpansees (Pan troglodytes) is, verskil in dieselfde mate van mense.

Die DNA-volgorde wat reguit in kontras tussen die 2 genome kan wees, is 99 % soortgelyk aan mekaar.

Wanneer DNS-invoegings en -delesies in ag geneem word, deel mense en sjimpansees nietemin 96% van hul volgorde. Op die proteïenverhouding word 29 % van die gene wat vir soortgelyke aminovolgordes kodeer, in sjimpansees en mense gevind.

Die nuutste bevindinge oor hoe sjimpansees optree en aanneem, het -weereens- bewys dat daar effektief na hierdie primate verwys kan word as die "neefs" van mense.

Hulle raas nie net soos ons nie, maar daarby, glimlag in stilte, hulle is gourmands, hulle speel, hulle is bewus van die waarheid wat hulle voel en kan onderskei tussen waar en onwaar, benewens hul houding om vriendskap te kweek.

1. Sjimpansees lok 'n geveg uit

Van al die wêreld se spesies is mense en sjimpansees onder die baie enigstes wat aan groepe deelneem om verskillende lede van hul eie spesie aan te val. In verskillende frases is elke spesie in staat om doelbewus 'n geveg uit te lok.

En binne die geval van primate, word gevegte nie veroorsaak deur inmenging met mense nie, wat vir 'n rukkie verkeerdelik beskou is as die rede vir die aanwysers van aggressiwiteit wat deur hierdie diere vertoon word.

Wat hulle tref om gewelddadige dade te pleeg, is 'n aanpasbare tegniek, hoofsaaklik gebaseer op die evalueringsproses.

Aggressiwiteit verhoog in digter bevolkings en in hierdie waarin daar’s 'n groter verskeidenheid van mans. En die slagoffers is dikwels lede van mededingende gemeenskappe.

2. Sjimpansees is bewus van die waarheid wat hulle aanneem

Sjimpansees het meta-kognisie, dat’s, hulle kan repliseer op hul eie idees en sielkundige prosesse, soos gedemonstreer nie te lank gelede deur navorsers.

In ooreenstemming met die outeurs is hierdie primate bewus van wat hulle doen en het geen idee nie, en hoofsaaklik op grond daarvan kan hulle rofweg vertroue in hul antwoorde toon en dienooreenkomstig optree, wat hulle dus in staat stel om slim keuses te maak.

3. Sjimpansees verkies om te speel

Kinders is nie diegene wat ure spandeer om te geniet en baie pret te hê nie. Sjimpansees spandeer baie ure met pret—wat die gedragswetenskaplikes beskryf het as enige oefening wat geen duidelike of vinnige voordele inhou nie—, elkeen deur hul kinderjare en hul "jeug".

Wetenskaplikes by die Kollege van Pisa (Italië) het getoon dat sosiale speletjies, dit’s, hierdie wat egter nie alleen uitgevoer word met verskillende sjimpansees nie, hulle help om stewige sosiale verhoudings te bou en samewerkende houdings te ontwikkel.

En as mense verander sportmetodes en speelmaats namate primate ontwikkel. Onder verskillende kwessies is speletjies meer samewerkend in die vroeë kinderjare, en word ekstra aggressief namate jonger primate ouer word.

4. Sjimpansees is eerlik en eties

Die gewete is net’t kenmerkend vir mense. Sjimpansees diskrimineer ook deur te besluit watter gedrag onvanpas is, veral wanneer dit jonger en kindersjimpansees raak.

In 'n navorsing wat op die Kollege van Zürich gedoen is en wat in die tydskrif Human Nature gedruk is, het dit duidelik geblyk dat as 'n sjimpansee tonele sien van 'n kind wat deur een ander lid van sy persoonlike spesie beseer of vermoor word, dit met verontwaardiging reageer en woede, een ding wat nie voorkom in omstandighede van geweld onder volwasse ape nie.

Die navorsing dui daarop dat hierdie primate het 'n manier van moraliteit wat’s net soos dié van mense.

Veral sjimpansees is geneig om eerlike en egalitêre skenkings te gee, en net tevrede te wees met hierdie soort geskenke van hul vriende.

"Vir sjimpansees -wat baie samewerkend in die natuur is, verteenwoordig dit 'n evolusionêre voordeel om delikaat te wees ten opsigte van die gelyke verdeling van belonings as gevolg van samewerking wat hulle bevoordeel", sê die skrywers van die ontleding.

5. Sjimpansees mak vriendskap

In geval van enige twyfel, vra eenvoudig vir Filippo Aureli, wat—na ’n radikale navorsing oor die gedrag van daardie primate—

tot die gevolgtrekking gekom dat hulle omring deur goeie pelle woon, dit’s, "nie die enigste onverwante mens wat tyd saam met hulle spandeer nie, maar wat hulle addisioneel bystaan ​​in omstandighede van konfrontasie, maaltye deel en saamwerk".

Hulle troos mekaar selfs en verlig verskillende groeplede se stres, soos Aureli en kollegas gedemonstreer het in 'n navorsing wat in PNAS gedruk is.

Wanneer 'n maat gekies word, is primate selektief. In ooreenstemming met navorsing wat deur die Kollege van Wene gedoen is, word aangename verhoudings gevestig tussen sjimpansees wat sekere persona-eienskappe deel.

Veral die mees gesellige mense kom saam met mekaar, terwyl verskillende skaam sjimpansees verskillende ewe bedeesde mense soek met die doel om sosiaal te verkeer.

Dit lyk soos die "ooreenkoms-impak" by mense, wat net die neiging is om hierdie onderwerpe as vriende te hê wat soos onsself lyk.

6. Sjimpansees is fynproewers

Aangesien hulle geen toegang tot supermarkte of eetplekke het nie, is sjimpansees bereid om na enige afstand te reis om hul gunsteling elemente te soek met die doel om 'n sappige feesmaal saam te stel.

Dit was die gevolgtrekking wat nie te lank gelede deur wetenskaplikes van die Harvard Universiteit (VSA) bereik is nie, wat boonop bewys het dat sjimpansees 'n keuse vir gekookte eerder as ongekookte maaltye met mense deel, benewens die vermoë om die transformasieprosesse te ken wat plaasvind wanneer maaltye gekook word.

Tussen die styl van gekookte aartappel en dié van 'n rou een, kies primate sonder om te skroom vir die vroeëre.

Die een faktor wat ontbreek vir hulle om deurdagte kokke te wees, sê navorsers, is om die kaggel te beheer. Maar as hulle’re gegee 'n verhitte pot of pan, eksperimente bied dat hulle geleer word dadelik leer hoe om dit in gebruik te neem.

7. Sjimpansees het 'n numeriese herinneringspan

As jy aanvaar dat mense beter as sjimpansees presteer in alle kognitiewe vermoëns, is jy verkeerd.

Omdat dit voorkom, is die krag van 'n jonger (5-jarige) sjimpansee om die getalle te onthou wat op 'n aansienlik verhoogde platform vertoon word, as dié van 'n volwasse mens, in ooreenstemming met 'n eksperiment wat op die Universiteit van Kyoto (Japan) uitgevoer is. .

Wetenskaplikes skryf dit toe aan 'n gelyke van eidetiese of fotografiese herinnering, dat’s, die krag om intiem te onthou wat’s gesien of gehoor, wat tans in menslike jongmense en wat afneem met ouderdom.

8. Hulle weet leer hoe om te glimlag

Hierdie primate kan in stilte glimlag, hardop raas, of uitbars van die lag, 'n verspreiding en aanpasbaarheid om optimistiese gevoelens te praat wat tot nou toe as 'n nuwe menslike funksie beskou is.

Elke klein dingetjie beteken dat gesigsuitdrukkings wat aan lag gekoppel is, reeds by ons primaatvoorouers teenwoordig was, wat lank vroeër vertoon het as wat die mens gevorderd is.

Die een glimlag wat vir die mens kenmerkend lyk, is die sogenaamde Duchenne-glimlag, 'n spontane uitdrukking wat herkenbaar is aan die onwillekeurige sametrekking van die orbicularis oculi-spier -

wat die oë omring—, wie se sametrekking die wange laat lig en plooie of “kraai se tone” oor die oë tik.

Dit is die ware en ware glimlag en is gekoppel aan die aktivering van die verstand se limbiese sisteem -waar gevoelens gegenereer word-, soos jare in die verlede deur die Franse neuroloog Guillaume Duchenne gedemonstreer.

9. Sjimpansees gebruik instrumente

Een van dr. Jane Goodall se mees noodsaaklike ontdekkings was dat sjimpansees instrumente gebruik. Terwyl ons hulle nie kon gebruik om na smaaklike termiete soos ons primaatverhoudings te soek nie, is hulle beslis nuttig vir byna elke ander deel!

10. Sjimpansee het 'n groter breingrootte

Hoewel die menslike brein is groter, dit’s struktureel soortgelyk aan 'n sjimpansee se. Dit beteken sjimpansees kan deur redeneer, abstraheer en veralgemening. Hulle sal selfs hulself in 'n spieël erken—die meeste verskillende diere kan’t!

11. Sjimpansees het 'n hoër sin

Sjimpansees sien en ervaar die wêreld baie soos ons. Hulle sin van sig, reuk, luister na en kontak is soortgelyk aan ons persoonlike ooreenkomste tussen mense en sjimpansees.

12. Sjimpansees het kielietjies

Sjimpansees raas wanneer hulle gekielie word. Jy getuig van Tango, die inwonende Tchimpounga Sanctuary-hond wat Mambou tot onderwerping kielie.

13. Sjimpansees het deelgewoontes

As jongmense, ons’re geleer om te deel. Weet jy dat sjimpansees hul maaltye en instrumente deel?

14. Sjimpansees is empaties

Sjimpansees praat nie net soos 'n mens nie, boonop toon hulle uitgebreide gevoelens saam met plesier, teleurstelling, besorgdheid en selfs empatie.

Ander aanbevole leeswerk

15. Sjimpansees het bene en stelsel identies aan die mens

'n Sjimpansee se liggaam is soortgelyk aan 'n mens s'n. Nou het ons identiese bene, spiergroepe, senuweestelsels en 'n identiese verskeidenheid vingers en tone.

16. Sjimpansees is spanjagter

Een van vele vroegste ontdekkings wat Jane Goodall gemaak het, was dat sjimpansees vir vleis jag. Net soos mense doen hulle dit in spanne.

17. Sjimpansees is sosiaal

Soos ons, word die eerste 5 jaar van 'n sjimpansee se lewe spandeer om te geniet, te sosialiseer en 'n kragtige baba-ma-band te skep.

18. Sjimpansees het betekenisvolle lyftaal

Soos mense gebruik sjimpansees lyftaal om te praat. Hulle soen, druk mekaar, klop mekaar weer, hou vingers vas en skud hul vuiste.

Ek hoop hierdie artikel oor ooreenkomste tussen mense en sjimpansees was die moeite werd om te lees.


Rys, die eerste gewasplant wat in volgorde geplaas word, kan help om wêreldhonger te beveg, sê Science-outeurs

Vertalings van hierdie vrystelling is beskikbaar in Japannees, Chinees (vereenvoudig) en Chinees (tradisioneel). Om die vertalings te sien, benodig jy Adobe Acrobat Reader 5.0 met Asiatiese lettertipepakket. Jy kan hierdie weergawe van die Adobe-webwerf aflaai.

Elke dag sterf 24 000 mense van honger en verwante oorsake, en 800 miljoen mense gaan honger slaap. Namate die menslike bevolking uitbrei en landbougrond krimp, word verwag dat voedseltekorte - wat deur droogte, politieke onrus, armoede of ander komplekse redes veroorsaak word - toenemend akuut sal word.

Die genetiese kode agter rys, 'n stapelvoedsel vir meer as die helfte van die wêreld se bevolking, "sal verbeterings in voedingsgehalte, oesopbrengs en volhoubare landbou bespoedig om in die wêreld se groeiende behoeftes te voorsien," het Donald Kennedy, hoofredakteur van die tydskrif, gesê. Science , uitgegee deur die American Association for the Advancement of Science (AAAS).

Verbasend genoeg kan rys baie meer kompleks wees as wat wetenskaplikes ooit geraai het, dig bevolk met baie klein gene - miskien selfs meer gene as die menslike genoom. Die rysgenoom kan ook 'n laekoste-padkaart verskaf om soortgelyke graangewasse soos mielies, koring en gars te ondersoek.

Rys, wetenskaplik bekend as Oryza sativa ("of-EYE-za sah-TEE-va"), is die hoofbron van kalorieë vir meer as 'n derde van die wêreld se bevolking.

Die rysstam, indica, gerangskik deur Jun Yu van die Beijing Genomics Institute en die Universiteit van Washington Genoom Sentrum, met kollegas by 11 Chinese instellings, is 'n belangrike subspesie in China en ander Asiatiese-Stille Oseaan-streke. Deur die indica-stam met 'n ander variëteit te kruis, produseer 'n superbaster met 'n 20- tot 30 persent hoër opbrengs per hektaar as ander rysgewasse.

'n Tweede span, gelei deur Stephen Goff en kollegas by Syngenta, het die japonica, of Nipponbare-subspesie, wat in meer droë streke voorkom, bestudeer. Rys met 'n hoër vitamien-inhoud kan die gevolg wees van die Syngenta-navorsing, het Goff gesê: Die japonica-genoom moet die geen openbaar wat verantwoordelik is vir Beta-karoteen biosintetiese weë, wat vitamien A-produksie vergemaklik. Genetiese inligting oor rys kan ook die begin maak vir geharder, meer plaagbestande gewasse, en help om die graan se bruikbaarheid vir baksteenkonstruksie, waterfiltrasie en verskeie ander gebruike te verbeter, het hy bygevoeg.

Die indica-volgorde, toeganklik by GenBank, en die japonica-volgorde, toeganklik deur Syngenta en in borg met Science, sal wetenskaplikes help om verder genomika-navorsing te doen en uiteindelik die globale voedselvoorraad te verbeter. ’n Nuwe AAAS-ooreenkoms, Electronic Information For Libraries (EIFL), sal inligting wat in Science gepubliseer is, vrylik beskikbaar stel aan streke waar dit waarskynlik die meeste goed sal doen. Kragtens die EIFL-ooreenkoms sal nie-winsgewende organisasies in 41 van die wêreld se armste lande gratis toegang kry tot referate wat in Science gepubliseer is.

Die konsepvolgorde vir indica-rys, wat deur Jun Yu en kollegas geproduseer word, bevat 466 miljoen basispare - 3,7 keer groter as die enigste ander opeenvolgende plantgenoom, die mosterdplant, Arabidopsis, maar 6,7 keer kleiner as die menslike genoom.

Hoe vergelyk die rysgenoom met die menslike genoom? Die Indica-genoom bevat 45 000-56 000 gene, en die gemiddelde lengte van elke geen is 4 500 basispare lank. Die aantal menslike gene word nog gedebatteer, maar kan ongeveer 30 000 tot 40 000 wees, met 'n gemiddelde geenlengte van 72 000 basispare. Arabidopsis, sluit 'n geskatte 25 498 gene in, met 'n gemiddelde geenlengte van ongeveer 2 000 basispare.

Verskille in geenlengte kan verskillende meganismes vir die generering van proteïendiversiteit aandui: Die indica-genoom (soos die Arabidopsis-genoom) toon tekens van uitgebreide geenduplisering, met meer as 70% van die gene wat gedupliseer is.

Duplisering van kleiner gene kan die proteïendiversiteit produseer wat nodig is vir aanpasbare evolusie in plante, stel Yu se span voor. Gewerwelde diere, soos mense, kan diverse proteïene genereer deur prosesse soos geensplyting wat relatief groter gene opbreek en weer in nuwe kombinasies saamstel.

Sowat 1,7 persent van die indica-genoom bestaan ​​uit eenvoudige volgordeherhalings, en komplekse volgordeherhalings maak nog een persent uit. Eenvoudige herhalings behels net 'n paar basispare, en kan nuttige "merkers" of verwysingspunte langs die genoom wees.

Komplekse herhalings, of "transponeerbare elemente," is DNS-volgordes wat om die genoom spring. Terwyl die meeste transposons in die menslike genoom binne die introne, of nie-koderende gedeelte van gene, gevind word, is die meeste transposons in die twee plantgenome tussen gene geleë, het navorsers opgemerk.

Om die indica-genoom te volgorde, het Yu en kollegas dieselfde "heelgenoom-haelgeweermetode" gebruik, wat voorheen gebruik is om die vrugtevlieg-genoom te volgorde, en deur private navorsers wat die menslike genoom volgorde bepaal.

Yu se span het baie DNS-brokkies van bekende lengte van regoor die rysgenoom gegenereer. Die hoeveelheid brokkies, gerangskik volgens die streke waar hul DNS-volgordes oorvleuel, was genoeg om die genoom ongeveer vier keer te bedek. Die navorsers het toe die basispaarvolgorde vir elke brokkie bepaal, en 'n rekenaarprogram gebruik om hulle in langer segmente saam te stel. Hierdie segmente (genoem "contigs," aangesien hulle verwys na genomiese streke waar aaneenlopende DNS-volgordes oorvleuel) is dan georden en saamgestel in 103 044 groter komponente wat "steiers" genoem word.

Die navorsers het gene binne die indica-genoom gesoek deur die rysvolgordes direk te vergelyk met bekende geenvolgorde wat in openbare databasisse gedeponeer is, en vanaf geenvoorspellingsagtewareprogramme. Hulle het ook sagtewareprogramme gebruik om die rysgene volgens algemene funksionele kategorieë te klassifiseer, soos metabolisme, sellulêre kommunikasie en selgroeiregulering.

Om akkuraatheid te bevestig, het Yu se groep alle publiek beskikbare rysgeenvolgorde en rysgeenmerkers versamel en na daardie volgordes in die indica-konsep gesoek. Hul bevindinge dui daarop dat die indica genoom konsep dek 92 persent van die hele rys genoom.

In 'n tweede fase van navorsing sal die span 'n meer gedetailleerde volgorde vervaardig wat geïntegreer word met fisiese en genetiese kaarte van die rysgenoom. Die meer gedetailleerde volgorde moet enige leemtes in die huidige konsep openbaar wat gene kan bevat, en al die gene in funksionele kategorieë plaas.

VERGELYKING VAN RYS EN ARABIDOPSIS

Yu se vergelyking van die indica- en Arabidopsis-genome het 'n paar ooreenkomste tussen die twee plantgenome aan die lig gebring, in vergelyking met die menslike genoom (soos geenduplisering). Maar die ontleding het ook interessante verskille tussen hierdie twee plante aan die lig gebring, wat die twee hooftipes saaddraende plante, eensaadlobbige en tweesaadlobbige plante verteenwoordig. In die treffendste vergelyking word 80,6 persent van Arabidopsis-gene in rys gevind, maar slegs 49,4 persent van die indica-gene word in Arabidopsis gevind.

Hierdie asimmetrie kan daarop dui dat die rysgenoom 'n "superset" van die Arabidopsis-genoom is, die resultaat van 'n massiewe geendupliseringsgebeurtenis, en kan lig werp op hoe eensaadlobbige en tweesaadlobbige soorte ongeveer 200 miljoen jaar gelede ontwikkel en afgewyk het.

Die japonica-konsepvolgorde, vervaardig deur Stephen A. Goff en kollegas, bevat 389 van hul skatting van 420 miljoen basispare vir die rysgenoom. Sagteware-voorspellingsprogramme dui daarop dat die japonica-genoom tussen 42 000 en 63 000 gene bevat. Die span se ontleding sluit nie 'n gemiddelde geenlengte in nie, maar hulle dui aan dat die rye wat waarskynlik gene is, langer as 500 basispare is.

Soos die indica-genoom, blyk dit dat die japonica-genoom groot dupliseringsgebeure ondergaan het: Ongeveer 75 persent van die voorspelde gene in die japonica-genoom kan duplikate wees. Baie van hierdie duplisering is moontlik in relatief klein episodes bewerkstellig, en die mees onlangse dupliseringsgebeurtenis is dalk glad nie so onlangs nie, wat 40 miljoen tot 50 miljoen jaar gelede plaasgevind het, stel Goff en die ander voor.

Die wetenskaplikes het meer as 40 000 eenvoudige-volgorde-herhalings van twee, drie en vier basispare geïdentifiseer. Soos met indica-eenvoudige-volgorde-herhalings, kan dit nuttige merkers wees vir teling- en bevolkingsgenetikastudies.

Goff se groep het ook die haelgeweermetode gebruik om die japonica-genoom te volgorde, en uiteindelik die opeenvolgende brokkies in 38 357 kontigs saam te stel. Although the researchers used some publicly funded rice genome data as markers to guide the assembly, no public rice genome data was incorporated into their draft.After translating the predicted genes into proteins, the researchers used another software program to sort them into functional categories. The results indicate that the majority of classified japonica genes are involved in cell communications and metabolism. The analysis also identified specialized phosphate transporter genes, critical for plants' uptake of this important nutrient from the soil.

More than 95 percent of publicly available rice gene sequences, and 99 percent of a proprietary collection of over 100,000 rice cDNA sequences, are also contained within the japonica draft genome, Goff said.

As with indica , researchers said their draft is incomplete, but "provides a solid foundation for completing a high-accuracy sequence, enabling gene identification and facilitating physical and genetic mapping."

The rice genome may also aid researchers working on the genomes of other important cereal crops such as maize and wheat. Goff and colleagues were able to match 98 percent of publicly available maize, wheat and barley protein sequences to sequences within the japonica genome. Analysis also confirms that rice shows extensive "synteny" with these cereals--or, conservation of gene order and orientation between comparable chromosomes. The considerable overlap in genomes may make it easier to search for genes of interest, and to identify key regulatory regions across the genomes of these important crops.

COMPARING RICE AND ARABIDOPSIS

Goff's comparison of the japonica and Arabidopsis genomes revealed similarities in genes related to disease resistance, and in some flowering time genes. Like the indica draft, the japonica draft contains roughly double the number of genes in the Arabidopsis genome, and around 88 percent of Arabidopsis ' genes can be found in the rice genome.

The japonica team searched for signs of any lateral transfer of genes between the rice and human genomes, a topic of recent interest, with the advent of genetically modified foods. Although rice and humans do share some sequence data, "there was no evidence to indicate that these genes or any genetic material had been laterally transferred to humans or human ancestors," suggesting that gene transfer from genetically modified rice would be unlikely, according to Goff's team.

The American Association for the Advancement of Science (AAAS) is the world's largest general scientific organization, and publisher of Science . Founded in 1848, the AAAS serves 134,000 members, as well as 273 affiliated organizations, representing 10 million individual scientists.

For additional information on this research, or to obtain artwork, please contact the AAAS News and Information Office at (202) 326-6440, or [email protected] Registered journalists may find information on the EurekAlert! web site, http://www. eurekalert. org.

(World hunger statistics, cited above, were developed by the United Nations World Food Programme.)

Vrywaring: AAAS en EurekAlert! is nie verantwoordelik vir die akkuraatheid van nuusvrystellings wat op EurekAlert geplaas is nie! deur bydraende instellings of vir die gebruik van enige inligting deur die EurekAlert-stelsel.


Space aliens are breeding with humans, university instructor says. Scientists say otherwise.

Maybe you've never seen any space aliens, but recent polls indicate that up to 6 percent of Americans claim to have been abducted by them. The experience doesn't sound pleasant. The extraterrestrials are often said to take their captives to their saucers, lay them out on a table and extract sperm from the men and impregnate the women.

If you're familiar with UFO lore, you know there are a couple of common explanations for these breeding experiments. One is that the aliens are in a reproductive bind on their home world: They can no longer successfully procreate and so have come to Earth to use humans as incubators to spawn alien offspring. The other is that the aliens are producing hybrid beings that will somehow help them take over our planet.

Scientists, of course, are dubious of such claims. After all, there's never been any good evidence that the abductions are taking place. No one ever seems to bring along a cellphone to take photos or to pocket an artifact from the saucers.

But an instructor at the University of Oxford in England believes the abductions are real. Young-hae Chi, who teaches Korean at the university, also claims to know what the aliens have in mind. In lectures given at the university, he says they're creating alien-human hybrids as a hedge against climate change. To support his unorthodox theory, Chi notes that for several decades the number of reported alien abductions has risen. He bases this statement on the work of David Jacobs, a retired Temple University historian who has published several books on ufology and who runs the International Center for Abduction Research.

Jacobs has interviewed more than a thousand people who claim to have been abducted, using hypnotic regression that apparently allows them to recall their unearthly encounters with aliens. (Mind you, this too is controversial, and Jacobs himself admits that people should be skeptical of these recollections.)

Chi takes the claims at face value, and links the growing number of abductees cataloged by Jacobs to the increase in atmospheric greenhouse gases. He doesn't imply a cause and effect: The abduction experiment is not responsible for global warming. Rather, it's a reaction to it. The extraterrestrials are producing hybrids that can better withstand the rigors of a toastier planet. By producing a new model of Homo sapiens, this project would eliminate the need for difficult climate accords or elaborate geoengineering projects. It would also help the aliens themselves — who are said to be living among us — by preserving the part of their DNA that's carried by the temperature-tolerant hybrids.

Verwante

Space 'Zoo hypothesis' may explain why we haven't seen any space aliens

Of course, human-alien hybrids, no matter how well adapted to a warmer world, don't address the crux of the climate change problem. Even unimproved humans can handle hotter temperatures after all, they already live in a plethora of steamy environments including the Congo, Amazonia and downtown Tucson. Rising sea levels could be dealt with too, by building dikes along the seaboards and writing off Miami Beach.

But it's the other inhabitants of the planet that are problematic — crops and critters that will either migrate toward the poles or disappear altogether. These, after all, are essential to both our environment and our food supply. Does the Oxford instructor presume that these other earthly residents are also being re-engineered by the aliens?

In addition, Chi's argument rests on the fact that two things have simultaneously increased in the past several decades: the number of reported abductions and the concentration of atmospheric carbon dioxide. Of course, many other things have risen during this time, too — including the price of bacon and the number of TV channels. It's a big jump from a coincidence in timing to an alien project to produce a climate-resistant species.

Eventually, this weird theory will be vindicated or vanquished by observation. Chi says the reason we don't see the aliens is that they are largely unrecognizable. "The first generation hybrids still have physical features distinctive to aliens'" he told NBC News MACH in an email. "But from the second generation . they have almost indistinguishable bodily features from those of humans, although they may still carry at least one fourth of alien genes."

The inability to discern anything odd about the appearance of the hybrids is both convenient and unconvincing. They live among us, but we don't notice. And meanwhile, the concentration of atmospheric carbon dioxide continues to climb. It seems unlikely that humanity will ultimately find this situation less threatening thanks to an alien re-build.

But still, you might want to check your 23andMe results. Maybe you're already a hybrid.


6 Traits Humans Inherited From Fish

What’s so fishy about human anatomy? A lot! Just look at these gifts from our aquatic ancestors.

1. Embryos

Look closely at any mammal, bird, or amphibian embryo—they all look the same. That’s because they all inherited genes from a common, fishy ancestor. During the middle stage of development—called the phylotypic period—a special combination of those genes becomes active, while some get turned off. Those active genes become the blueprints for your body.

2. Our Voice

Fish can’t talk, but they do have gills—and that’s where our voices come from. Just like fish, human embryos have gill arches (bony loops in the embryo’s neck). In fish, those arches become part of the gill apparatus. But in humans, our genes steer them in a different direction. Those gill arches become the bones of your lower jaw, middle ear, and voice box.

3. Sense of Hearing

How did gills become part of the ear? Just look at the fossil evidence. The ancient fish Eustenopteron lived about 370 million years ago. It had a problem, though: A small part of the jawbone—the hyomandibula—poked into its gills. A few million years later, that same pesky bone formed a cavity by the ear of Eustenopteron’s descendents. There, it started amplifying sound—travel down the fossil record even further, and you’ll see that the bone had become the stape, the part of the ear that helps us hear.

4. Hernias

Fish gonads sit near the heart. In human embryos, the gonads form deep in the chest—just like in fish. However, since we’re warm-blooded, these gonads need to go somewhere cool. After 12 weeks, they start to descend, and for men, they break through the body wall and form testicles. But breaking through the body wall leaves behind a weak spot, which is why it’s relatively easy for humans to get hernias.

5. Fingers

Fish don’t have fingers, but they do have the gene that makes fingers possible. In the 1980s, scientists discovered a special gene called “sonic hedgehog,” which helps animals form digits. When scientists mutated sonic hedgehog in various animals, the creatures all grew extra fins and fingers (people with polydactylism—that is, six fingers—suffer from a sonic hedgehog overload). A surge in sonic hedgehog helped ancient fish crawl onto land.

6. Our Faces

You know that groove above your upper lip, just below the nose? That’s the philtrum. It’s there because, as an embryo, your face looked kind of fishy. Your eyes started at the side of your head and your nostrils and lips grew at the top (you looked a little like an eel). After a couple of months, those features migrated: Your eyes squeezed inward while your lips and nose dropped. The transformation left behind a tiny divot above your upper lip, and gave men everywhere a place to grow terrible mustaches.


Do plants have distinctive DNA genomes from each other like humans do? - Biologie

OPSOMMING

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2015, Broadening Participation. The fellowship supports a research and training plan in a host laboratory for the Fellow and a plan to broaden participation of groups under-represented in science. The title of the research plan for this fellowship to Christopher A. Emerling is "The genetics of extreme adaptations in anteaters, armadillos, sloths and other mammals". The host institution for this fellowship is University of California, Berkeley, and the sponsoring scientist is Dr. Michael W. Nachman.

Anteaters, armadillos and sloths (xenarthrans) represent a group of mammals that evolved from a common ancestor 65 million years ago in South America. The group as a whole is characterized by a variety of extreme features, including a major reduction in dentition, an inability to discern colors and see in bright light, and an incredibly low metabolism. Individually the three subgroups have bizarre adaptations as well, such as strict ant- and termite-eating in anteaters and upside-down locomotion in tree sloths. While together these and other traits demonstrate the strangeness of xenarthrans, many of these features have independently evolved in various groups of mammals. The presence of such extreme traits in different mammals provides the opportunity to test for the genetic basis of the evolution of anatomical and physiological features. This research involves sequencing the genomes of eight xenarthrans and making comparisons with published genome sequences from mammals with similar adaptations. In addition to their value in studies of evolution, armadillos have been valuable in the study of leprosy and Chagas disease in humans. The xenarthrans as a group may also serve as model organisms for other health conditions such as those that affect the teeth (e.g., amelogenesis imperfecta) and vision (e.g., congenital achromatopsia). This research promises to identify candidate mutations that illuminate the evolutionary history but may also be used for diagnosis and/or treatment of these conditions.

Training goals include how to sequence and assemble genomes with cutting edge technology and other career advancement activities. To broaden participation of groups under-represented in biology, the Fellow is mentoring students in the UC Berkeley Biology Scholars Program, particularly those from disadvantaged backgrounds providing science career outreach at K-12 schools and community colleges with high enrollment of underrepresented minorities and low income students and providing evolution outreach to the public through blogging (https://evolutionforskeptics.wordpress.com) and oral presentations.

PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

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PROJECT OUTCOMES REPORT

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation NSF has not approved or endorsed its content.

Understanding how genomes can evolve and lead to major changes in anatomy and physiology is one of the major goals of biologists today. Thanks to the increasing cost-efficiency of DNA sequencing, assembling the genomes of rare and unusual species has become easier than ever. For my NSF Postdoctoral Fellowship: Broadening Participation in Biology, I sought to sequence and assemble the genomes of a group of organisms with particularly unusual traits: xenarthrans. Xenarthrans include the armored armadillos, the long-snouted ant-and-termite-eating specialist anteaters, and the slow, tree-dwelling, leaf-eating sloths. Scientists believe that these unusual mammals are each other's closest living relatives, with other mammals having independently evolved very similar adaptations, such as the ant-and-termite-eating pangolins and aardvarks, and the leaf-eating colobus monkeys and flying lemurs. So by studying changes in the DNA of xenarthrans and mammals that evolved similar (convergent) adaptations, we can understand how changes in genes can lead to radical differences in form.

I tackled this topic at the Museum of Vertebrate Zoology in the University of California, Berkeley, mentored by the Director, Michael Nachman. Through my work, partnering with Frédéric Delsuc at the Université de Montpellier, the Broad Institute at Harvard, and numerous other colleagues, we sequenced the genomes of 12 xenarthran genomes (and counting!) and discovered numerous examples of possible genomic adaptations in mammals, such as those related to the loss of teeth, the production of the sleep hormone melatonin, taste reception, digging burrows, nighttime vision and others.

One result that we are particularly excited about involves the digestion of insect prey. Insects have exoskeletons made of chitin, and research has shown that mammals like humans, mice and bats have a gene that makes an enzyme (chitinase) that can digest it. We found that there are actually up to five such genes in mammals, with insect-eaters having the most, including armadillos, anteaters, tarsiers and aardvarks, and meat- or plant-eaters having the fewest, including sloths, elephants, tigers, and polar bears. Furthermore, we found evidence that the ancestors of most mammals had five chitinase genes, pointing to an insect-based diet while these animals lived alongside the dinosaurs. But when dinosaurs went extinct 66 million years ago, many herbivorous and carnivorous mammal groups began to lose the genes, suggesting that they stopped eating insects when the dinosaurs disappeared. This conclusion has long been suggested by paleontologists, so we were excited to find that genomes tell the same story. In fact, carnivores and herbivores have remnants of chitinase genes in their genomes, pointing to their insect-eating past, and humans do too!

While in the Museum of Vertebrate Zoology, surrounded by an amazing collection of birds, reptiles and amphibians, and their associated experts, I was inspired to take advantage of the situation and extend my study of genomic adaptations to these animals. My favorite results include (1) genomic evidence that turtles, crocodilians and birds had ancestors with a third eye, similar to many kinds of lizards, (2) a genetic remnant of claws in the legless snakes, and (3) evidence from penguin, owl and kiwi genomes implicating a gene in the production of red feathers in many birds.

Not only did this fellowship train me as a scientist, but it also allowed me to mentor and perform outreach towards individuals from various groups of people underrepresented in biology. I mentored four such undergraduate students on projects, aimed at providing experience in scientific research, as well as advising them how to navigate a post-undergraduate world, including applying for graduate schools and deciding on scientific careers. I also volunteered in schools in Berkeley and Oakland, partnering with Community Resources for Science in the Be A Scientist program, which paired me with middle-school students to mentor them in a six-week science project, and the Bay Area Scientists In Schools program, which involved giving hands on lessons to 1st graders relating teeth shape to diets in mammals. This partnership also involved giving science demos for kids at Discovery Days in AT&T Park, plus Dinner with a Scientist, where I answered the questions of 4th-5h graders about being a scientist while showing museum specimens to teach about coloration in birds. My position at the Museum of Vertebrate Zoology also allowed me to lead tours of the museum to elementary through college students, including via the Program Your Future Academy and Scientists in the Classroom (National Center for Science Education). I also performed outreach to communities traditionally skeptical of evolution research, including by blogging for Understanding Evolution: Evo the News, presenting at Think Evolution VIII: A summer institute for science educators, and writing in my personal blog, Evolution for Skeptics (https://evolutionforskeptics.wordpress.com).

This fellowship provided the training of a young scientist for the workforce, produced numerous scientific publications and presentations, with more in the works, and allowed for the mentoring of and outreach to numerous people from groups underrepresented in biology.


Humans probably not alone in how we perceive melodic pitch

The specialized human ability to perceive the sound quality known as 'pitch' can no longer be listed as unique to humans. Researchers at Johns Hopkins report new behavioral evidence that marmosets, ancient monkeys, appear to use auditory cues similar to humans to distinguish between low and high notes. The discovery infers that aspects of pitch perception may have evolved more than 40 million years ago to enable vocal communication and songlike vocalizations.

A summary of the research will be published online in the journal Verrigtinge van die Nasionale Akademie van Wetenskappe on Dec. 28, 2015.

"Pitch perception is essential to our ability to communicate and make music," says Xiaoqin Wang, Ph.D., a professor of biomedical engineering at the Johns Hopkins University School of Medicine, "but until now, we didn't think any animal species, including monkeys, perceived it the way we do. Now we know that marmosets, and likely other primate ancestors, do."

Marmosets are small monkeys native to South America that are highly vocal and social. Wang, an auditory neuroscientist and biomedical engineer, has been studying their hearing and vocalizations for the past 20 years. A decade ago, he says, he and his team of researchers identified a region in the marmoset brain that appears to process pitch. Nerve cells in that region, on the edge of the primary auditory cortex, only 'fired' after marmosets were exposed to sounds with pitch, like the shifting in high and low notes associated with a melody, not those without, such as noise. Human brains show similar activity in that region, as other researchers have reported, he notes.

What was missing was behavioral evidence that the marmosets could perceive and respond to differences in pitch the way humans do, and Wang's laboratory group spent years developing behavioral tests and electrophysiological devices designed to monitor subtle changes in the monkeys' neural activity. Part of their work was to train a group of marmosets to lick a waterspout only after hearing a change in pitch.

Wang says that other animal species have been reported to show pitch perception, but none have shown the three specialized features of human pitch perception. First, people are better at distinguishing pitch differences at low frequencies than high. For example, people who hear tones of 100, 200, 300 and 400 hertz played simultaneously hear four separate sounds, but they hear only one sound when tones of 1,100, 1,200, 1,300 and 1,400 hertz are played together, even though the frequency intervals are the same in both cases.

Second, humans are able to pick up on subtle changes in the spread between pitches at low frequencies or hertz, so they notice if a series of tones is increasing by 100 hertz each time and then introduces a tone only 90 hertz higher.

And third, at high frequencies, peoples' ability to perceive pitch differences among tones played simultaneously is related to how sensitive they are to the rhythm, or timed fluctuations, of sound waves.

Through a series of hearing tests, with waterspout licks as a readout, Wang's team, led by graduate student Xindong Song, determined that marmosets share all three features with humans, suggesting that human components of pitch perception evolved much earlier than previously thought.

The American continent, with its marmosets in place, broke away from the African land mass approximately 40 million years ago, before humans appeared in Africa, so it's possible that this humanlike pitch perception evolved before that break and was maintained throughout primate evolution in Africa until it was inherited by modern humans. Another possibility is that only certain aspects of pitch perception were in place before the split, with the rest of the mechanisms evolving in parallel in Old and New World monkeys. According to Wang, more stringent tests are needed to determine whether existing Old World monkeys perceive pitch like humans do.

"In addition to the evolutionary implications of this discovery, I'm looking forward to what we will be able to learn about human pitch perception now that we have a primate relative we can study behaviorally and physiologically," says Wang. "Now we can explore questions about what goes wrong in people who are tone deaf and whether perfect pitch is an inherited or learned trait."


Genetic roadmap to building an entire organism from a single cell

Whether a worm, a human or a blue whale, all multicellular life begins as a single-celled egg.

From this solitary cell emerges the galaxy of others needed to build an organism, with each new cell developing in the right place at the right time to carry out a precise function in coordination with its neighbors.

This feat is one of the most remarkable in the natural world, and despite decades of study, a complete understanding of the process has eluded biologists.

Now, in three landmark studies published online April 26 in Wetenskap, Harvard Medical School and Harvard University researchers report how they have systematically profiled every cell in developing zebrafish and frog embryos to establish a roadmap revealing how one cell builds an entire organism.

Using single-cell sequencing technology, the research teams traced the fates of individual cells over the first 24 hours of the life of an embryo. Their analyses reveal the comprehensive landscape of which genes are switched on or off, and when, as embryonic cells transition into new cell states and types.

Together, the findings represent a catalog of genetic "recipes" for generating different cell types in two important model species and provide an unprecedented resource for the study of developmental biology and disease.

"With single-cell sequencing, we can, in a day's work, recapitulate decades of painstaking research on the decisions cells make at the earliest stages of life," said Allon Klein, HMS assistant professor of systems biology and co-corresponding author of two of the three Wetenskap studies.

Biomedically, these baseline resources for how organisms develop are as important as having baseline resources for their genomes, the researchers said.

"With the approaches that we've developed, we're charting what we think the future of developmental biology will be as it transforms into a quantitative, 'big-data'-driven science," Klein said.

In addition to shedding new light on the early stages of life, the work could open the door to a new understanding of a host of diseases, said Alexander Schier, the Leo Erikson Life Sciences Professor of Molecular and Cellular Biology at Harvard, and a corresponding author of the third study.

"We foresee that any complex biological process in which cells change gene expression over time can be reconstructed using this approach," Schier said. "Not just the development of embryos but also the development of cancer or brain degeneration."

One at a time

Every cell in a developing embryo carries within it a copy of the organism's complete genome. Like construction workers using only the relevant portion of a blueprint when laying a building's foundation, cells must express the necessary genes at the appropriate time for the embryo to develop correctly.

In their studies, Klein collaborated with co-authors Marc Kirschner, the HMS John Franklin Enders University Professor of Systems Biology, Sean Megason, HMS associate professor of systems biology and colleagues to analyze this process in zebrafish and western claw-toed frog (Xenopus tropicalis) embryos, two of the most well-studied model species in biology.

The researchers leveraged the power of InDrops, a single-cell sequencing technology developed at HMS by Klein, Kirschner and colleagues, to capture gene expression data from each cell of the embryo, one cell at a time. The teams collectively profiled more than 200,000 cells at multiple time points over 24 hours for both species.

To map the lineage of essentially every cell as an embryo develops, along with the precise sequence of gene expression events that mark new cell states and types, the teams developed new experimental and computational techniques, including the introduction of artificial DNA bar codes to track the lineage relationships between cells, called TracerSeq.

"Understanding how an organism is made requires knowing which genes are turned on or off as cells make fate decisions, not just the static sequence of a genome," Megason said. "This is the first technological approach that has allowed us to systematically and quantitatively address this question."

In the study co-led by Schier, the research team used Drop-Seq -- a single-cell sequencing technology developed by researchers at HMS and the Broad Institute of MIT and Harvard -- to study zebrafish embryos over 12 hours at high time resolution. Teaming with Aviv Regev, core member at the Broad, Schier and colleagues reconstructed cell trajectories through a computational method they named URD, after the Norse mythological figure who decides all fates.

Schier and colleagues profiled more than 38,000 cells, and developed a cellular "family tree" that revealed how gene expression in 25 cell types changed as they specialize. By combining that data with spatial inference, the team was also able to reconstruct the spatial origins of the various cells types in the early zebrafish embryo.

Recipe for success

In both species, the teams' findings mirrored much of what was previously known about the progression of embryonic development, a result that underscored the power of the new approaches. But the analyses were unprecedented in revealing in comprehensive detail the cascades of events that take cells from early progenitor or "generalist" states to more specialized states with narrowly defined functions.

The teams identified otherwise difficult-to-detect details such as rare cell types and subtypes and linked new and highly specific gene expression patterns to different cell lineages. In several cases, they found cell types emerging far earlier than was previously thought.

For scientists striving to answer questions about human disease, these data could be powerfully illuminating. In regenerative medicine, for example, researchers have for decades aimed to manipulate stem cells toward specific fates with the goal of replacing defective cells, tissues or organs with functional ones. Newly gleaned details about the sequence of gene expression changes that precipitate the emergence of specific cell types can propel these efforts further.

"With these datasets, if someone wants to make a specific cell type, they now have the recipe for the steps that those cells took as they formed in the embryo," Klein said. "We've in some sense established a gold standard reference for how complex differentiation processes actually progress in embryos, and set an example for how to systematically reconstruct these types of processes."

When combined with one of the core concepts in biological inquiry -- the idea of disrupting a system to study what happens -- single-cell sequencing can yield insights difficult to attain before, Klein said.

As a proof of principle, Klein, Megason and colleagues used the CRISPR/Cas9 gene editing system to create zebrafish with a mutant form of chordin, a gene involved in determining the back-to-front orientation of a developing embryo. Schier and colleagues took a similar approach by profiling zebrafish with a mutation in a different patterning gene known as one-eyed pinhead.

When analyzed with single-cell sequencing, the teams confirmed previously known descriptions of chordin and one-eyed pinhead mutants, and could describe in detail or even predict the effects of these mutations on developing cells and nascent tissues across the whole embryo.

Unexpectedly, the groups independently found that at the single-cell level, gene expression was the same in mutants and wildtype, despite the loss of an essential signaling pathway. The proportions of different cell types, however, changed.

"This work only became possible through recent technologies that let us analyze gene expression in thousands of individual cells," Schier said. "Now the scale is much larger, so that we can reconstruct the trajectory of almost all cells and all genes during embryogenesis. It is almost like going from seeing a few stars to seeing the entire universe."

Rethinking definitions

The research teams also demonstrated how these data can be mined to answer long-standing fundamental questions in biology.

When Klein, Kirschner, Megason and colleagues compared cell-state landscapes between zebrafish and frog embryos, they observed mostly similarities. But their analyses revealed numerous surprises as well. One such observation was that genes marking cell states in one species were often poor gene markers for the same cell state in the other species. In several instances, they found that the DNA sequence of a gene -- and the structure of the protein it encodes -- could be nearly identical between species but have very different expression patterns.

"This really shocked us, because it goes against all the intuition we had about development and biology," Klein said. "It was a really uncomfortable observation. It directly challenges our idea of what it means to be a certain 'cell type.'"

The reason that these differences were not spotted before, the researchers hypothesize, is that computational analyses "pay attention" to data in a way fundamentally different from how humans do.

"I think this reflects some level of confirmation bias. When scientists find something conserved between species, they celebrate it as a marker," Megason said. "But often, all the other nonconserved features are ignored. Quantitative data helps us move past some of these biases."

In another striking finding, the teams observed that the process of cell differentiation into distinct cell types -- which is commonly thought to occur in a tree-like structure where different cell types branch off from a common ancestor cell -- can form "loops" as well as branches.

For example, the neural crest -- a group of cells that give rise to diverse tissue types including smooth muscle, certain neurons and craniofacial bone -- initially emerges from neural and skin precursors, but is well-known to generate cells that appear almost identical to bone and cartilage precursors.

The new results suggest that similar loops might occur in other situations. That cells in the same state can have very different developmental histories suggests that our hierarchical view of development as a "tree" is far too simplified, Klein said.

All three teams also identified certain cell populations that existed in a kind of intermediate "decision making" state. Schier and colleagues found that, at certain key developmental branch points, cells appeared to go down one developmental trajectory but then changed their fate to another trajectory.

Klein, Megason, Kirschner and colleagues made a related observation that, early in development, some cells activated two distinct developmental programs. Though those intermediate cells would eventually adopt a single identity, these discoveries add to the picture of how cells develop their eventual fate and hint that there may be factors beyond genes involved in directing cell fate.

"With multilineage cells, we have to start wondering if their final fate is being determined by some selective force or interaction with the environment, rather than just genetic programs," Kirschner said.

Future foundation

The newly generated data sets and the new tools and technologies developed as part of these studies lay the foundation for a wide spectrum of future exploration, according to the authors.

Developmental biologists can gather more and higher quality data on many species, follow embryos further in time and perform any number of perturbation experiments, all of which can help improve our understanding of the fundamental rules of biology and disease.

These resources can also serve as a focal point for collaboration and interaction since most labs do not have the depth of expertise needed to exploit all the data and information generated, the authors noted.

"I think these studies are creating a real sense of community, with researchers raising questions and interacting with each other in a way that harkens back to earlier times in the study of embryology," Kirschner said.

The three studies, Schier said, are an example of how the scientific community can work on complementary questions to answer important questions in biology.

"Instead of competing, our groups were in regular contact over the past two years and coordinated the publication of our studies," he said. "And it is great how complementary the three papers are -- each highlights different ways such complex data sets can be generated, analyzed and interpreted."

The next conceptual leap, the teams suggest, will be to better understand how cell-fate decisions are made.

"Right now, we have a roadmap, but it doesn't tell us what the signs are," Megason said. "What we need to do is figure out the signals that direct cells down certain roads, and what the internal mechanisms are that allow cells to make those decisions."

Whatever the future holds, these data sets will leave their mark.

"The beauty of working on an organism is that this is it," Klein said. "Ten, 20 years from now, we can still be sure zebrafish and frogs are going to develop according to the same patterns."

All three research teams have made their data sets and tools available as interactive, browsable online resources.


Kyk die video: What are Genome Evolution, Mutations, Gene Duplications, Gene Losses, and Inversions? (Oktober 2022).