Inligting

Is daar enige tegniek wat een stel selchromosome vinnig kan uitbrei?

Is daar enige tegniek wat een stel selchromosome vinnig kan uitbrei?


We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

Aanvaar dat 'n seltipe baie skaars is terwyl dit geïsoleer is en moeilik is om in vitro uit te brei, en ek wil meer van sy chromosome hê, is daar enige tegniek, in vivo of in vitro of ex vitro, enige wat sal tel, wat my toelaat om vinnig uit te brei die hoeveelheid van daardie chromosome?

Ek weet dit klink vreemd maar net 'n bietjie nuuskierigheid~

Dankie


Telomere-uitbreiding draai verouderingsklok in gekweekte menslike selle terug, het studie bevind

’n Nuwe prosedure kan die lengte van menslike telomere, die beskermende pette op die punte van chromosome wat aan veroudering en siektes gekoppel word, vinnig en doeltreffend vergroot, volgens wetenskaplikes aan die Stanford University School of Medicine.

Behandelde selle tree op asof hulle baie jonger as onbehandelde selle is, en vermeerder met verlating in die laboratoriumskottel eerder as om te stagneer of dood te gaan.

Die prosedure, wat die gebruik van 'n gewysigde tipe RNA behels, sal die vermoë van navorsers verbeter om groot getalle selle vir studie of geneesmiddelontwikkeling te genereer, sê die wetenskaplikes. Velselle met telomere wat deur die prosedure verleng is, kon tot 40 keer meer verdeel as onbehandelde selle. Die navorsing kan dui op nuwe maniere om siektes wat deur verkorte telomere veroorsaak word, te behandel.

Telomere is die beskermende doppe op die punte van die stringe DNA wat chromosome genoem word, wat ons genome huisves. By jong mense is telomere ongeveer 8 000-10 000 nukleotiede lank. Hulle verkort egter met elke seldeling, en wanneer hulle 'n kritieke lengte bereik, hou die sel op om te deel of sterf. Hierdie interne "klok" maak dit moeilik om die meeste selle vir meer as 'n paar selverdubbelings in 'n laboratorium te laat groei.

'Draai die interne horlosie terug'

"Nou het ons 'n manier gevind om menslike telomere met soveel as 1 000 nukleotiede te verleng, deur die interne klok in hierdie selle terug te draai met die ekwivalent van baie jare van menslike lewe," sê Helen Blau, PhD, professor in mikrobiologie en immunologie aan Stanford en direkteur van die universiteit se Baxter-laboratorium vir stamselbiologie. "Dit verhoog die aantal selle wat beskikbaar is vir studies soos dwelmtoetsing of siektemodellering aansienlik."

'n Referaat wat die navorsing beskryf, is vandag in die FASEB Joernaal. Blau, wat ook die Donald E. en Delia B. Baxter Professorskap beklee, is die senior skrywer. Na-doktorale geleerde John Ramunas, PhD, van Stanford deel hoofouteurskap met Eduard Yakubov, PhD, van die Houston Methodist Research Institute.

Die navorsers het gemodifiseerde boodskapper-RNA gebruik om die telomere uit te brei. RNA dra instruksies van gene in die DNA na die sel se proteïenvervaardigende fabrieke. Die RNA wat in hierdie eksperiment gebruik is, bevat die koderingsvolgorde vir TERT, die aktiewe komponent van 'n natuurlik voorkomende ensiem genaamd telomerase. Telomerase word uitgedruk deur stamselle, insluitend dié wat aanleiding gee tot sperm- en eierselle, om te verseker dat die telomere van hierdie selle in tip-top vorm bly vir die volgende generasie. Die meeste ander soorte selle druk egter baie lae vlakke van telomerase uit.

Verbygaande effek 'n voordeel

Die nuut ontwikkelde tegniek het 'n belangrike voordeel bo ander potensiële metodes: Dit is tydelik. Die gemodifiseerde RNA is ontwerp om die sel se immuunreaksie op die behandeling te verminder en die TERT-koderende boodskap 'n bietjie langer te laat bly as wat 'n ongewysigde boodskap sou. Maar dit verdwyn en is binne ongeveer 48 uur weg. Na daardie tyd begin die nuut verlengde telomere weer progressief verkort met elke seldeling.

Die verbygaande effek is ietwat soos om die petrolpedaal te tik in een van 'n vloot motors wat stadig ry tot stilstand. Die motor met die ekstra oplewing van energie sal verder gaan as sy eweknieë, maar dit sal steeds tot stilstand kom wanneer sy vorentoe momentum bestee is. Op 'n biologiese vlak beteken dit dat die behandelde selle nie onbepaald gaan verdeel nie, wat hulle te gevaarlik sou maak om as 'n potensiële terapie by mense te gebruik as gevolg van die risiko van kanker.

Die navorsers het bevind dat so min as drie toedienings van die gemodifiseerde RNA oor 'n tydperk van 'n paar dae die lengte van die telomere in gekweekte menslike spier- en velselle aansienlik kan verhoog. 'n Byvoeging van 1 000 nukleotied verteenwoordig 'n meer as 10 persent toename in die lengte van die telomere. Hierdie selle het baie meer keer in die kultuurskottel verdeel as onbehandelde selle: ongeveer 28 keer meer vir die velselle, en ongeveer drie keer meer vir die spierselle.

“Ons was verbaas en bly dat gemodifiseerde TERT-mRNA gewerk het, want TERT is hoogs gereguleer en moet aan ’n ander komponent van telomerase bind,” het Ramunas gesê. "Vorige pogings om mRNA-koderende TERT af te lewer het 'n immuunrespons teen telomerase veroorsaak, wat skadelik kan wees. Daarteenoor is ons tegniek nie-immunogenies. Bestaande verbygaande metodes om telomere uit te brei werk stadig, terwyl ons metode oor net 'n paar dae optree om telomere om te keer. verkorting wat plaasvind oor meer as 'n dekade van normale veroudering. Dit dui daarop dat 'n behandeling met ons metode kort en seldsaam kan wees."

Potensiële gebruike vir terapie

"Hierdie nuwe benadering baan die weg na die voorkoming of behandeling van siektes van veroudering," het Blau gesê. "Daar is ook hoogs aftakelende genetiese siektes wat verband hou met telomere verkorting wat kan baat vind by so 'n potensiële behandeling."

Blau en haar kollegas het in telomere begin belangstel toe vorige werk in haar laboratorium getoon het dat die spierstamselle van seuns met Duchenne-spierdistrofie telomere het wat baie korter was as dié van seuns sonder die siekte. Hierdie bevinding het nie net implikasies om te verstaan ​​hoe die selle funksioneer - of nie funksioneer nie - om nuwe spiere te maak, maar dit help ook om die beperkte vermoë om geaffekteerde selle in die laboratorium vir studie te laat groei, te verduidelik.

Die navorsers toets nou hul nuwe tegniek in ander soorte selle.

"Hierdie studie is 'n eerste stap in die rigting van die ontwikkeling van telomere uitbreiding om selterapieë te verbeter en om moontlik versteurings van versnelde veroudering by mense te behandel," sê John Cooke, MD, PhD. Cooke, 'n mede-outeur van die studie, was voorheen 'n professor in kardiovaskulêre medisyne by Stanford. Hy is nou voorsitter van kardiovaskulêre wetenskappe by die Houston Methodist Research Institute.

"Ons werk daaraan om meer te verstaan ​​oor die verskille tussen seltipes, en hoe ons daardie verskille kan oorkom om hierdie benadering meer universeel bruikbaar te maak," sê Blau, wat ook 'n lid is van die Stanford Institute for Stem Cell Biology en Regeneratiewe medisyne.

"Dit kan dalk eendag moontlik wees om spierstamselle in 'n pasiënt met Duchenne-spierdistrofie te teiken, byvoorbeeld om hul telomere uit te brei. Daar is ook implikasies vir die behandeling van toestande van veroudering, soos diabetes en hartsiektes. Dit het werklik die deure om alle soorte potensiële gebruike van hierdie terapie te oorweeg."


  1. Tradisionele kruisteling
    Vir millennia was tradisionele kruisteling die ruggraat van die verbetering van die genetika van ons gewasse. Tipies word stuifmeel van een plant op die vroulike deel van die blom van 'n ander geplaas, wat lei tot die produksie van sade wat basters van die twee ouers is. Planttelers kies dan die plante wat die voordelige eienskappe het waarna hulle soek om na die volgende generasie voort te gaan. Appelvariëteite soos die Honeycrisp-appel is op hierdie manier ontwikkel – duisende basterbome is gemaak, gekweek en getoets om net een wonderlike nuwe variëteit te vind met 'n kombinasie van gene wat nog nooit voorheen bestaan ​​het nie. Moderne plantteling gebruik dikwels genetiese merkers om die seleksieproses te bespoedig, en kan gene van wilde variëteite en nouverwante spesies inkorporeer. Hier is 'n paar video's oor die verskillende tegnieke wat planttelers gebruik. Kruisteling kan slegs van gewenste eienskappe gebruik maak as dit in dieselfde of naverwante spesies is, daarom is bykomende tegnieke ontwikkel om nuwe eienskappe te skep vir planttelers om te gebruik.
  2. Mutagenese
    In die natuur ontstaan ​​nuwe eienskappe dikwels deur spontane mutasies. In die afgelope eeu is hierdie proses nageboots deur wetenskaplikes, wat muterende chemikalieë (soos etielmetaansulfonaat) of radioaktiwiteit gebruik het om ewekansige mutasies in plante te genereer, en daarna vir nuwe of gewenste eienskappe gekeur het. Vir meer inligting oor mutagenese, sien asseblief hierdie pos. Die Ruby Red en die Star Ruby variëteite van pomelo's is ontwikkel met behulp van ioniserende straling. Die mutasies wat hulle dra gee hierdie vrugte hul kenmerkende dieprooi kleur. Hierdie artikel van die New York Times verskaf baie bykomende voorbeelde van gewasse wat met hierdie tegniek ontwikkel is.
  3. Poliploïdie
    Die meeste spesies het 2 stelle chromosome: een stel wat van elke ouer geërf word. Dit staan ​​bekend as diploïdie. Poliploïdie is die voorkoms van meer as 2 stelle chromosome. Dit kan natuurlik voorkom, maar poliploïdie kan ook deur die gebruik van chemikalieë geïnduseer word. Hierdie gewasmodifikasietegniek word gewoonlik gebruik om die grootte van vrugte te vergroot of om hul vrugbaarheid te verander. Byvoorbeeld, die pitlose waatlemoen het 3 stelle chromosome en word geskep deur 'n waatlemoen met 4 stelle chromosome te kruis met 'n ander waatlemoen wat 2 stelle het, wat 'n steriele waatlemoen met 3 stelle chromosome maak, tot groot vreugde van piekniekliefhebbers regdeur die wêreld. Aartappelspesies het ook baie verskillende aantal chromosoomkopieë, en aartappeltelers moet gewoonlik die kopiegetal van hul variëteite verander om nuwe eienskappe daarin te kweek (Meer oor hierdie proses hier).
  4. Protoplast Fusion
    Wanneer spermselle in stuifmeel met die eierselle in die eierstokke van 'n blom kombineer, is dit 'n samesmelting van twee selle in een. Protoplast-fusie is 'n kunsmatige weergawe van hierdie proses. Voordelige eienskappe kan van een spesie na 'n ander verskuif word deur die protoplaste (‘naakte’ selle sonder die selwande wat plante hul struktuur gee) saam te smelt en 'n plant uit die nuut saamgesmelte sel te laat groei. Een van die mees gebruikte eienskappe wat met hierdie proses ontwikkel is, is die oordrag van manlike steriliteit tussen spesies. As jy 'n manlike steriele plant het, kan jy makliker bastersade maak – veral vir plante wat klein blommetjies het en moeilik kruisbaar is. Manlike steriliteit is bekendgestel aan rooikool van daikon radyse, wat dit makliker maak om bastersade van hierdie gewas te produseer.
  5. Transgenese
    Transgenese is die proses waardeur jy een of meer gene van 'n ander organisme in 'n organisme inbring. Dit behels gewoonlik die hantering en wysiging van die DNS self in 'n proefbuis, en dan verpak dit om dit in die nuwe organisme te plaas. Daar is verskeie maniere om die nuwe geen of ‘transformeer’ 'n plant soos biolistiek (die “gene gun”) bekend te stel, met behulp van Agrobacterium – 'n natuurlike organisme wat DNS in plante plaas, of deur elektrisiteit te gebruik – 'n proses genaamd elektroporasie. Transgeniese plante is gegenereer met baie nuttige eienskappe, waarvan sommige gekommersialiseer is. Papajas is byvoorbeeld getransformeer met 'n geen van die virus wat die plant besmet om dit bestand teen die virus te maak. Ander eienskappe sluit in insekweerstand, onkruiddoderverdraagsaamheid, en droogtetoleransie, en meer. Die skepping van hierdie ‘transgeniese’ gewasse werk alhoewel die gene van enige ander spesie kan kom, want die genetiese taal is universeel vir alle lewe op hierdie planeet. Gene wat van dieselfde spesie ontstaan ​​het, kan ‘cisgenies’ of ‘intragenies’ genoem word. Vir meer inligting, sien hierdie vraestel.
  6. Genoom redigering
    Genoomredigering bestaan ​​uit die gebruik van 'n ensiemstelsel om die DNA van 'n sel in 'n bepaalde volgorde te verander. Daar is verskillende stelsels wat vir genoomredigering gebruik kan word, waarvan die mees belowende die CRISPR-Cas9-stelsel is (vir meer inligting oor genoomredigering en hoe dit werk, sien asseblief hierdie pos). Die sulfonielureum (US) onkruiddoderverdraagsame canola is ontwikkel om boere in staat te stel om onkruid beter te beheer en om wisselbou moontlik te maak. Die gewas is geskep met behulp van 'n gepatenteerde genoomredigeringstelsel bekend as Rapid Trait Development System (RTDS). Jy kan moontlik die genoom van enige gewas wysig om enige geen te verander wat jy wou hê, van die bekendstelling van nuwe gene tot die herstel van ‘natuurlike’ allele van die voorvaders van ons gewasse.

Elkeen van hierdie metodes het ooreenkomste en verskille, en sommige werk beter vir sommige eienskappe eerder as ander. Elkeen van hulle verander die genetiese samestelling van die plant om nuttige eienskappe saam te kombineer om landbou te verbeter. Almal van hulle het voorbeelde wat op plase gekweek word en voordele lewer, almal kan op een of ander manier gepatenteer word, en almal kan onbedoelde gevolge hê.

Sosiaal en polities word die produkte van hierdie metodes egter baie verskillend behandel. Die feit dat die veranderinge wat hierdie tegnieke instel nie strook met hoe hulle behandel word wanneer dit kom by debatte oor die regulasies vir gesondheid en omgewingsveiligheid, en politieke debatte oor etikettering het bekend geword as die “Frankenfood Paradox.& #8221 Transgenese bring byvoorbeeld baie minder veranderinge en onbedoelde gevolge voort as mutagenese (sien hierdie artikel), terwyl mutagenese algemeen aanvaar en geïgnoreer word in politieke besprekings.


Is daar enige tegniek wat een stel selchromosome vinnig kan uitbrei? - Biologie

Selverdeling (mitose) in eukariotiese selle

    I. Interfase : Tydperk van selsiklus wanneer sel nie deel nie. (15 uur)

    A.G1 Fase: Sellulêre organelle begin dupliseer.

B. S-Fase: DNA-replikasie (chomosome word verdubbel).

II. M-Fase (Tydperk van Selafdeling): (2 uur)

    A. Karyokinese (mitose of kernafdeling):
    Dit sluit Profase, Metafase, Anafase en Telofase in.

2. Homoloë Chromosome: Vader en Moeder

Enkelchromosome en verdubbelde chromosome (chromosoomdublette). Begin met profase, die chromosome verskyn as dublette. Die helder pienk dubbeltjies verteenwoordig 'n stel moederlike verdubbelde chromosome wat oorspronklik van die moeder se eiersel afkomstig is. Die gestreepte blou dubbeltjies verteenwoordig 'n stel vaderlike verdubbelde chromosome wat oorspronklik van die vader se sperm afkomstig is. Diploïede (2n) organismes soos mense het twee stelle chromosome, een haploïede (n) stel van die vader en een haploïede (n) stel van die moeder. Bevrugting van die twee haploïede geslagselle (eier en sperm) lei tot 'n diploïede sigoot (n + n = 2n). Homoloë pare dublette word voorgestel deur een groot pienk en een groot blou verdubbelde chromosoom van ooreenstemmende grootte, en een klein pienk en een klein blou dubbeltjie van ooreenstemmende grootte. In hierdie diagram is daar twee pare homoloë chromosoomdublette. In 'n menslike sel is daar tydens profase 23 pare homoloë chromosoomdubbeltjies, 'n totaal van 46 dublette en 92 chromatiede. Nadat die chromatiede tydens anafase geskei het en die sel tydens telofase verdeel het, het die resulterende dogterselle 23 pare enkelchromosome, 'n totaal van 46. Die enkelchromosome word weer verdubbel tydens die S-fase van interfase, voor die aanvang van profase.

In hierdie diagram bevat die sel 3 pare homoloë enkelchromosome, 'n totaal van 6 chromosome. Aangesien die sel 'n totaal van 6 chromosome bevat, het dit 'n chromosoomgetal van 6. Chromosome A & a verteenwoordig een paar, B & b verteenwoordig 'n tweede paar, en C & c verteenwoordig 'n derde paar. Elke paar word 'n homoloë paar genoem omdat hulle ooreenstem in grootte en vorm. Een lid van elke paar kom van die moeder (pienk chromosoom) en een lid van elke paar kom van die vader (blou chromosoom). Drie pienk chromosome in hierdie sel (A, B & C) verteenwoordig een haploïede stel moederlike chromosome van die moeder. Drie blou chromosome (a, b & c) in hierdie sel verteenwoordig een haploïede stel vaderlike chromosome van die vader. Aangesien daar 2 stelle chromosome in hierdie diagram is, is die sel diploïed (2n).

Een chromatied van hierdie eukariotiese chromosoom-dubbelet is ontrafel, wat 'n gedraaide DNA-molekule toon wat om krale van histoonproteïen gedraai is. Elke proteïenkraal bevat ongeveer 200 basispare op sy oppervlak, terwyl die string tussenin uit ongeveer 50 basispare bestaan. Elke proteïenkraal met DNA op sy oppervlak word 'n nukleosoom genoem. Elke chromatied is in wese saamgestel uit 'n sterk opgerolde DNA-molekule en proteïen. Die chromatiede (DNA-molekules) is geheg in 'n gebied bekend as die sentromeer. In hierdie baie oorvereenvoudigde illustrasies word die sentromeer as 'n swart kol getoon. Dit verteenwoordig bloot 'n area waar die suster-DNS-molekules (chromatiede) geheg is.

3. Die M-Fase (Selafdelingsfase)

1. Interfase: Die sel is nie besig om te deel in hierdie tydperk nie. Die kern is saamgestel uit donker kleurmateriaal wat chromatien genoem word, 'n term wat gesamentlik op al die chromosome van toepassing is. Op hierdie stadium is die chromosome skraal (draadagtig) en is nie sigbaar as afsonderlike liggame nie. 'n Nukleolus is duidelik sigbaar binne die kern. Hierdie liggaam is saamgestel uit ribosomale RNA en is die plek van proteïensintese binne die sel. Voor seldeling is twee pare proteïenliggame genaamd sentriole teenwoordig in die sitoplasma aan die een kant van die sel. Sentriole is nie tipies in plantselle teenwoordig nie.

2. Profase: Een van die sentriole beweeg na die teenoorgestelde kant van die sel. Die teenoorgestelde punte van die sel word pole genoem, soos die pole van die aarde. Elke sentriool bestaan ​​nou uit 'n paar proteïenliggame omring deur stralende proteïenstringe wat die aster genoem word. Plantselle het tipies nie die aster of sentriole nie. Ook die kernmembraan disintegreer en die chromosome verkort en verdik sodat hulle as duidelike staafvormige liggame sigbaar is. Op hierdie tydstip word elke chromosoom verdubbel en bestaan ​​uit twee chromatiede. Elke chromatied is in wese saamgestel uit 'n sterk opgerolde DNA-molekule en proteïen. Die chromatiede (DNA-molekules) is geheg in 'n gebied wat bekend staan ​​as die sentromeer. In hierdie baie oorvereenvoudigde illustrasies word die sentromeer as 'n swart kol getoon.

3. Metafase: Die chromosoomdubbeltjies word gerangskik in die sentrale streek van die sel bekend as die ewenaar. Hulle is nie noodwendig 'n enkele lêer in lyn soos die tekening wys nie. Proteïendrade wat die spil genoem word, verbind die sentromeergebied van elke chromosoomdubbelt met die sentriole by die pole van die selle.

4. Anafase: Die chromatiede skei van mekaar by die sentromeergebied en die enkele chromosome beweeg na teenoorgestelde punte (pole) van die sel. Wanneer die chromatiede van mekaar skei word hulle nie meer chromatiede genoem nie. Daar word nou na hulle verwys as enkelchromosome. Die enkele chromosome word eintlik na teenoorgestelde punte van die sel getrek soos die spilvesels verkort word.

Die knolle van herfskrokus (Colchicum autumnale), 'n lid van die leliefamilie (Liliaceae), bevat die alkaloïed kolgisien, 'n spilgif wat depolimerisasie van mitotiese spilsels in tubuliensubeenhede veroorsaak. Dit los in wese die spil op en keer dat die sel sy mitotiese verdeling voltooi. Omdat kolgisien plantselle kan keer om te verdeel nadat die chromatiede tydens anafase van mitose geskei het, is dit 'n kragtige induseerder van poliploïdie. Sade en meristematiese knoppies kan met kolgisien behandel word, en die selle binne word poliploïed met veelvuldige stelle chromosome (meer as die diploïede getal). Poliploïdie in plante het 'n paar geweldige kommersiële toepassings omdat vreemde poliploïede (soos 3n triploïede) steriel en pitloos is. Poliploïede plante (soos 4n tetraploïede) produseer tipies groter blomme en vrugte. Trouens, baie van die vrugte en groente wat by supermarkte verkoop word, is poliploïede variëteite. Kolchisien het 'n ander mediese gebruik vir mense omdat dit die inflammasie en pyn van jig verminder. Dit word ook in kankerchemoterapie gebruik om te keer dat tumorselle verdeel en sodoende remissie van die kanker veroorsaak.

Twee bykomende alkaloïede (vinblastien en vincristine) van die Madagaskar maagdenpalm (Catharanthus roseus) is ook kragtige spilgifstowwe. Hierdie alkaloïede het bewys dat dit baie effektief is in chemoterapie-behandelings vir leukemie en Hodgkin se siekte (limfklier- en miltkanker). Soos kolgisien, veroorsaak hulle die ontbinding (depolimerisasie) van proteïenmikrotubuli wat die mitotiese spil in verdeelde selle uitmaak. Dit keer effektief dat die tumorselle verdeel, wat dus remissie van die kanker veroorsaak. Voordat maagdarm-alkaloïede as 'n behandeling gebruik is, was daar feitlik geen hoop vir pasiënte met Hodgkin se siekte nie. Nou is daar 'n 90 persent kans op oorlewing. Dit is 'n dwingende rede vir die behoud van die diverse flora en fauna in natuurlike ekosisteme. Wie weet watter geneesmiddels vir gevreesde siektes wag om in tropiese reënwoude of ander natuurlike habitatte ontdek te word.

5. Telofase: Die chromosome aan elke kant van die sel begin organiseer in aparte kerne, elkeen omring deur 'n kernmembraan. In die middel van die sel vorm 'n klowingvoor of vernouing, wat geleidelik dieper en dieper word totdat die sel in twee afsonderlike selle verdeel word. Hierdie sitoplasmiese verdeling word sitokinese genoem. Sitoplasmiese verdeling (sitokinese) in 'n plantsel word bewerkstellig deur 'n afskorting of selplaat eerder as 'n splitsingsvoor. Die volgende illustrasie toon selplaatvorming in 'n uiewortelpuntsel:

6. Interfase: Nou is ons weer terug na interfase, maar nou is daar twee dogterselle. Elke dogtersel is chromosomaal identies aan die oorspronklike (moeder) sel. Hulle het elkeen 'n kern wat 'n nukleolus en chromatien bevat. Die sentriole het in vier proteïenliggame verdeel en die aster het verdwyn. Gedurende hierdie fase sal die chromosome repliseer en duidelike chromosoomdubbeltjies word soos elke dogtersel profase ingaan.

Die vyf hooffases van plantmitose. Anders as diereselle, het plantselle nie sentriole of asters nie. Tydens telofase verdeel 'n partisie of selplaat die sitoplasma eerder as 'n splitsingsvoor.

5. Mitose & Embrioniese stamselle

A. Starfish embrio tydens die morula stadium. Dit bestaan ​​uit 'n bal van selle wat aktief verdeel wat oppervlakkig soos die veelvuldige vrugte van 'n moerbei lyk (vandaar die naam morula). Op hierdie stadium is elke sel ongespesialiseerd en kan moontlik ontwikkel tot 'n aparte organisme. 'n Menslike embrio is in die morula-stadium terwyl dit in die fallopiese buis af beweeg. Ten tyde van inplanting op die baarmoederwand (wat amptelik die aanvang van swangerskap aandui), bestaan ​​die embrio uit 'n hol bol of blastosist (blastula) wat bestaan ​​uit ongeveer 100 selle ongeveer so groot soos 'n gedrukte tydperk.
Veelvuldige vrugte van die swart moerbei (Morus nigra). Die
individuele eenhede is een-saad drupelets eerder as selle.
B. Hoogs vergrote aansig van 'n witvismorula wat verskeie stadiums van mitose toon: 1 = profase, 2 = metafase, 3 = anafase, 4 = telofase.

Let wel: Die ongedifferensieerde selle van menslike blastosiste word embrioniese stamselle genoem. Blastosiste kan in vitro gevorm word deur proefbuisbevrugtings. Ongedifferensieerde stamselle is veral merkwaardig omdat hulle aanleiding kan gee tot verskillende weefsels en organe. Deur komplekse geen-interaksies kan hierdie selle letterlik ontwikkel tot enige aantal seltipes wat in die menslike liggaam voorkom. Die kontroversie oor die gebruik van embrioniese stamselle in navorsing behels die vraag wat 'n mens uitmaak en wanneer die lewe amptelik begin. In 'n onlangse bespreking deur regse konserwatiewes oor wanneer lewe begin, is die term oösiet ingesluit. Ek is nie seker of hulle primêre sowel as sekondêre oösiete bedoel het nie. As die selle van morulas en blastosiste ook as mense beskou word (of Amerikaanse burgers soos sommige godsdienstige konserwatiewes voorstel), dan is diploïede somatiese selle in lewende mense ook, waarvan die kerne in ontkernde eierselle geplaas kan word. Bioloë in ander lande moet lag vir hierdie absolute snert.

Met die gesofistikeerde tegnieke van moderne biotegnologie het die kern van enige ongedifferensieerde sel die potensiaal om tot 'n kloon te groei as dit in 'n ontkernde eiersel geplaas word. Die slotsom hier is dat die selle in 'n noukeurig beheerde omgewing geplaas moet word om tot 'n mens te groei. Laasgenoemde selle kan in vivo (binne in lewende organisme) of in vitro (in 'n vat buite 'n lewende organisme) gekweek word. Stamselle wat in vitro gekweek word, bied 'n ongekende geleentheid vir die studie en begrip van menslike embriologie en die generering van weefsels en organe. Hierdie navorsing kan 'n merkwaardige potensiaal bied vir terapie en genesing vir baie vernietigende menslike siektes, insluitend verskeie vorme van diabetes, kankers van menslike weefsels, organe en beenmurg, en siektes van die sentrale senuweestelsel (soos Parkinson se siekte en Alzheimer se siekte). Afhangende van hoe hulle gekweek word, kan embrioniese stamselle moontlik tot weefsels en organe gegroei word wat die lewe van 'n kind of 'n volwasse mens kan red. Sommige teenstanders van embrioniese stamselnavorsing beskou menslike morulas en blastulas as mense en moet nie geoes word nie, selfs nie om die lewe van 'n geliefde te red nie. Plasentale en amniotiese weefsel kan 'n alternatiewe en minder omstrede bron van stamselle verskaf.

'n Menslike morula wat uit 16-32 selle bestaan.

6. Gewasse: Onbeheerde Seldeling

Wanneer selle abnormaal verdeel ontwikkel hulle dikwels in weefselmassas wat gewasse genoem word. Gewasse kan regdeur die liggaam geproduseer word en hulle kan kwaadaardig of goedaardig wees. Daar word dikwels na kwaadaardige gewasse verwys as kankers. Sommige menslike kankers word deur virusse veroorsaak, soos sekere vorme van die herpesvirus wat servikale kanker veroorsaak. Die meeste kankers is neoplastiese gewasse wat veroorsaak word deur mutasies in die DNA van selle. Hierdie mutasies meng in met die sel se vermoë om seldeling te reguleer en te beperk. Dormante selle gaan die M-fase van die selsiklus binne en begin buite beheer verdeel. Mutasies wat kankerveroorsakende onkogene aktiveer of tumoronderdrukkergene onderdruk, kan uiteindelik tot gewasse lei. Selle het meganismes wat foute in hul DNA herstel, maar mutasies wat herstel-ensieme beïnvloed, kan veroorsaak dat gewasse vorm. Een van die beste voorbeelde van laasgenoemde meganisme is 'n basaalselkarsinoom.

Oormatige blootstelling aan UV-straling van die son kan mutasies in ongedifferensieerde basale keratinosiete (basale selle) van die epidermis veroorsaak. Die spesifieke mutasie word 'n timiendimeer binne die DNA-molekule genoem. In normale DNA, pare die pirimidienbasis timien slegs met die purienbasis adenien. Wanneer twee aangrensende timienbasisse saambind, veroorsaak dit 'n abnormale konfigurasie of "kink" in die DNA. Gesonde selle kan hierdie fout herken en herstel deur eksisieherstel-ensieme. By sommige diere word die mutasie herstel deur DNS-fotolise-ensieme wat die dimeer uitknip (split). Mense met 'n genetiese geneigdheid vir velkanker kan onvoldoende herstelensieme hê as gevolg van mutasies wat die gene vir hierdie herstelmeganismes onderdruk. Alhoewel kwaadaardige basale sel karninome oor die algemeen nie metastaseer nie, kan hulle stadig diep lae van die vel en aangrensende weefsel binnedring en uiteindelik redelik vernietigend wees. Die volgende beeld toon die indringende groei van 'n basale selkarsinoom (tegnies 'n morfeaform bcc) wat die verwydering van ongeveer 1/3 van die skrywer se neus vereis het. Anders as die knopgroeivorm van sommige basale selkarsinome, vermeerder die morpheaform bcc in dieper weefsel met aggressiewe, tentakelagtige takke. Benewens 'n verhoogde aantal en digtheid van donkerkleurende basale selle, veroorsaak laasgenoemde tipe velkanker 'n verspreiding van fibroblaste binne die dermis en 'n verhoogde kollageenafsetting (sklerose) wat soos 'n litteken lyk. Die gewas verskyn as 'n witterige, wasagtige, sklerotiese gedenkplaat wat selde ulsereer. Dit vorm nie merkbare rowe soos in ander velkankers nie. Op die oppervlak van die skrywer se ala (kant van die neus), het hierdie karsimoom soos 'n klein, konkawe litteken gelyk, maar dit het omvattend tot omliggende weefsel gegroei. Alhoewel die son die noodsaaklike energiebron vir alle lewe op aarde is, kan dit ook 'n kragtige karsinogeen wees.

Op 'n positiewe noot vir sonblootstelling, begin sintese van vitamien D, 'n vitamien wat noodsaaklik is vir menslike biologiese funksie, met aktivering van 'n voorlopermolekule in die vel deur UV-strale. Ensieme in die lewer en niere verander dan die geaktiveerde voorloper en produseer uiteindelik kalsitrol, die mees aktiewe vorm van vitamien D. Gedurende die grootste deel van die jaar is 'n paar uur per week van sonblootstelling aan die gesig en arms voldoende om aan die liggaam se behoefte te voldoen. vir die geaktiveerde kalsitrolvoorloper. Oor die algemeen woon mense met 'n ligte vel in noordelike breedtegrade met 'n laer ligintensiteit in vergelyking met mense met donker vel van die tropiese breedtegrade. Mense met donker vel produseer groter konsentrasies melanien wat hul vel teen skadelike strale van die son beskerm. Basaalselkarsinome is skaars in Swartes en Asiërs, in vergelyking met Blankes met 'n ligte vel. Daar is voorgestel dat mense met 'n ligte vel van noordelike breedtegrade 'n effense voordeel kan hê in die sintetisering van vitamien D, veral gedurende maande van die jaar in streke met verminderde ligintensiteit.

Verdeelde menslike selle kan tydens profase en metafase gefotografeer word, en al die 46 chromosoomdubbeltjies kan in 23 homoloë pare gerangskik word. 'n Fotografiese of digitale gedrukte beeld wat 'n kariotipe genoem word, word dan gemaak wat al die chromosome netjies in homoloë pare wys, van 1 tot 23. Karotipes is baie nuttig om chromosomale abnormaliteite te bepaal, soos chromosomale delesies (ontbrekende gene) of verkeerde getalle. Byvoorbeeld, 'n persoon met Down-sindroom sal drie nommer 21-chromosome hê eerder as twee.

Kariotipes kan ook die geslag van 'n persoon openbaar. Benewens die 22 pare chromosome (outosome) in menslike somatiese (liggaams) selle, het wyfies 'n 23ste paar wat uit twee X-chromosome bestaan. Die 23ste paar mannetjies bestaan ​​uit 'n X- en 'n Y-chromosoom. Die kleiner Y-chromosoom bevat 'n DNS-gebied op die kort arm van die Y wat verantwoordelik is vir manlikisering van die fetus. By wyfies verskyn een van die twee X-chromosome as 'n gekondenseerde, donkerkleurige Barr-liggaam binne die kern van somatiese selle, naby die kernmembraan. Hierdie struktuur is vernoem na sy ontdekker, Murray Barr. Aangesien Barr-liggame slegs in kerne met meer as een X-chromosoom voorkom, is hulle nie in manlike selle teenwoordig nie. Tot in die vroeë 1990's kon die gebrek aan Barr-liggame in kerne van wangepiteelselle van vroue hulle diskwalifiseer vir kompetisie in die Olimpiese Spele.

Die kaliko kat is 'n seksuele mosaïek wat gekenmerk word deur vlekke van swart, geel en wit pels. Die gene (allele) vir swart en geel is aan dieselfde lokusse op twee verskillende X-chromosome gekoppel. Dit is hoekom kalikote tipies vroulik is omdat hulle twee X-chromosome het, een met die swart geen en een met die geel geen. Aangesien die swart geen dominant oor geel is, hoe ontwikkel die mosaïekkleurpatroon? The Barr body concept provides a nice cellular explanation for the patches of black and yellow fur. In regions with black fur, the black gene is active and the yellow gene is located on an inactive Barr body. In regions with yellow fur, the black gene is on the inactive Barr body while the yellow gene is on the active X chromosome. At an early stage in the cat's embryonic development, certain X chromosomes become inactive Barr bodies, apparantly at random. In the descendants of these cells, the same chromosomes are inactive, leaving the cells with only one functional allele for coat color. A rare calico male probably has an XXY karotype resulting in maleness, black fur and yellow fur. By the way, the white patches result from a gene interaction involving the "spotting gene," which blocks melanin synthesis entirely.

Gender verification in the Olympic Games now employs sophisticated DNA testing rather than counting Barr bodies within the nuclei of cells. The test is designed to detect the presence of the SRY gene (sex region Y chromosome), a region of DNA on the short arm of the Y chromosome responsible for masculinization of the fetus. Cells from the buccal mucosa (squamous epithelial cells), often called "cheek cells" in general biology classes, are obtained by gently scraping the inside of the mouth with a toothpick. The DNA in the nuclei of these cells is amplified using the PCR technique (polymerase chain reaction). If present, the SRY gene will show up as a unique banding pattern by electrophoresis on agar gels.

The following table shows different possible combinations of X and Y chromosomes in people. The gender of some of these chromosomal karyotypes and syndromes cannot be correctly identified using the Barr body technique:

The gender of the following chromosomal karyotypes and syndromes cannot be correctly identified using the Barr body technique. In addition the SRY test is not reliable in individuals with hormonal sex variations, such as androgen insensitivity and adrenogenital syndromes. For example, an XY person with androgen insensitivity has a Y chromosome with the SRY gene. Although they produce testosterone, they have a sex-linked gene on their X chromosome resulting in the lack of testosterone receptor proteins therefore, they do not develop male characteristics. In other words, they produce androgens but do not respond to them.


Abstrak

Bacterial genomes encode the biosynthetic potential to produce hundreds of thousands of complex molecules with diverse applications, from medicine to agriculture and materials. Accessing these natural products promises to reinvigorate drug discovery pipelines and provide novel routes to synthesize complex chemicals. The pathways leading to the production of these molecules often comprise dozens of genes spanning large areas of the genome and are controlled by complex regulatory networks with some of the most interesting molecules being produced by non-model organisms. In this Review, we discuss how advances in synthetic biology — including novel DNA construction technologies, the use of genetic parts for the precise control of expression and for synthetic regulatory circuits — and multiplexed genome engineering can be used to optimize the design and synthesis of pathways that produce natural products.


Identification of Chromosomes

The isolation and microscopic observation of chromosomes forms the basis of cytogenetics and is the primary method by which clinicians detect chromosomal abnormalities in humans. A karyotype is the number and appearance of chromosomes. To obtain a view of an individual&rsquos karyotype, cytologists photograph the chromosomes and then cut and paste each chromosome into a chart, or karyogram, also known as an ideogram.

In a given species, chromosomes can be identified by their number, size, centromere position, and banding pattern. In a human karyotype, autosomes or &ldquobody chromosomes&rdquo (all of the non&ndashsex chromosomes) are generally organized in approximate order of size from largest (chromosome 1) to smallest (chromosome 22). However, chromosome 21 is actually shorter than chromosome 22. This was discovered after the naming of Down syndrome as trisomy 21, reflecting how this disease results from possessing one extra chromosome 21 (three total). Not wanting to change the name of this important disease, chromosome 21 retained its numbering, despite describing the shortest set of chromosomes. The X and Y chromosomes are not autosomes and are referred to as the sex chromosomes.

The chromosome &ldquoarms&rdquo projecting from either end of the centromere may be designated as short or long, depending on their relative lengths. The short arm is abbreviated p (for &ldquopetite&rdquo), whereas the long arm is abbreviated q (because it follows &ldquop&rdquo alphabetically). Each arm is further subdivided and denoted by a number. Using this naming system, locations on chromosomes can be described consistently in the scientific literature.

Although Mendel is referred to as the &ldquofather of modern genetics,&rdquo he performed his experiments with none of the tools that the geneticists of today routinely employ. One such powerful cytological technique is karyotyping, a method in which traits characterized by chromosomal abnormalities can be identified from a single cell. To observe an individual&rsquos karyotype, a person&rsquos cells (like white blood cells) are first collected from a blood sample or other tissue. In the laboratory, the isolated cells are stimulated to begin actively dividing. A chemical called colchicine is then applied to cells to arrest condensed chromosomes in metaphase. Cells are then made to swell using a hypotonic solution so the chromosomes spread apart. Finally, the sample is preserved in a fixative and applied to a slide.

The geneticist then stains chromosomes with one of several dyes to better visualize the distinct and reproducible banding patterns of each chromosome pair. Following staining, the chromosomes are viewed using bright-field microscopy. A common stain choice is the Giemsa stain. Giemsa staining results in approximately 400&ndash800 bands (of tightly coiled DNA and condensed proteins) arranged along all of the 23 chromosome pairs. An experienced geneticist can identify each chromosome based on its characteristic banding pattern. In addition to the banding patterns, chromosomes are further identified on the basis of size and centromere location. To obtain the classic depiction of the karyotype in which homologous pairs of chromosomes are aligned in numerical order from longest to shortest, the geneticist obtains a digital image, identifies each chromosome, and manually arranges the chromosomes into this pattern.

Figuur (PageIndex<1>): A human karyotype: This karyotype is of a male human. Notice that homologous chromosomes are the same size, and have the same centromere positions and banding patterns. A human female would have an XX chromosome pair instead of the XY pair shown.

At its most basic, the karyotype may reveal genetic abnormalities in which an individual has too many or too few chromosomes per cell. Examples of this are Down Syndrome, which is identified by a third copy of chromosome 21, and Turner Syndrome, which is characterized by the presence of only one X chromosome in women instead of the normal two. Geneticists can also identify large deletions or insertions of DNA. For instance, Jacobsen Syndrome, which involves distinctive facial features as well as heart and bleeding defects, is identified by a deletion on chromosome 11. Finally, the karyotype can pinpoint translocations, which occur when a segment of genetic material breaks from one chromosome and reattaches to another chromosome or to a different part of the same chromosome. Translocations are implicated in certain cancers, including chronic myelogenous leukemia.

During Mendel&rsquos lifetime, inheritance was an abstract concept that could only be inferred by performing crosses and observing the traits expressed by offspring. By observing a karyotype, today&rsquos geneticists can actually visualize the chromosomal composition of an individual to confirm or predict genetic abnormalities in offspring, even before birth.


In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosome.

Most human cells contain 23 pairs of chromosomes. One set of chromosomes comes from the mother, while the other comes from the father. The twenty third pair is called the sex chromosomes, while the rest of the 22 pairs are called outosome.

Typically, biologically male individuals have one X and one Y chromosome (XY) while those who are biologically female have two X chromosomes. However, there are exceptions to this rule.

The sex chromosomes determine the sex of offspring. The father can contribute an X or a Y chromosome, while the mother always contributes an X.

The Y chromosome is one-third the size of the X chromosome and contains about 55 genes while the X chromosome has about 900 genes.

In genealogy, the male lineage is often traced using the Y chromosome because it is only passed down from the father.

All individuals carrying a Y chromosome are related through a single XY ancestor who (likely) lived around 300,000 years ago.

The Y chromosome contains a "male-determining gene," the SRY gene, that causes testes to form in the embryo and results in development of external and internal male genitalia. If there is a mutation in the SRY gene, the embryo will develop female genitalia despite having XY chromosomes.

Variation in the number of sex chromosomes in a cell is quite common. Some men have more than two sex chromosomes in all of their cells (the XXY variation is called the Klinefelter syndrome), and many men lose the Y chromosome from their cells as they age. Smoking may exacerbate this loss.

Some genes that were thought to be lost from the Y chromosome have actually relocated to other chromosomes.

Much of the Y chromosome is composed of repeating DNA segments. Specialized techniques are needed sequence and determine the arrangement of these highly similar segments.

Many health conditions are thought to be related to changes in genes expressed on the Y chromosome. This is currently an active area of research.

In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosome.

Most human cells contain 23 pairs of chromosomes. One set of chromosomes comes from the mother, while the other comes from the father. The twenty third pair is called the sex chromosomes, while the rest of the 22 pairs are called outosome.

Typically, biologically male individuals have one X and one Y chromosome (XY) while those who are biologically female have two X chromosomes. However, there are exceptions to this rule.

The sex chromosomes determine the sex of offspring. The father can contribute an X or a Y chromosome, while the mother always contributes an X.

The Y chromosome is one-third the size of the X chromosome and contains about 55 genes while the X chromosome has about 900 genes.

In genealogy, the male lineage is often traced using the Y chromosome because it is only passed down from the father.

All individuals carrying a Y chromosome are related through a single XY ancestor who (likely) lived around 300,000 years ago.

The Y chromosome contains a "male-determining gene," the SRY gene, that causes testes to form in the embryo and results in development of external and internal male genitalia. If there is a mutation in the SRY gene, the embryo will develop female genitalia despite having XY chromosomes.

Variation in the number of sex chromosomes in a cell is quite common. Some men have more than two sex chromosomes in all of their cells (the XXY variation is called the Klinefelter syndrome), and many men lose the Y chromosome from their cells as they age. Smoking may exacerbate this loss.

Some genes that were thought to be lost from the Y chromosome have actually relocated to other chromosomes.

Much of the Y chromosome is composed of repeating DNA segments. Specialized techniques are needed sequence and determine the arrangement of these highly similar segments.

Many health conditions are thought to be related to changes in genes expressed on the Y chromosome. This is currently an active area of research.


How Artificial Chromosomes Could Transform Humanity

Normally, an extra pair of chromosomes would be considered dangerous. But what if we could design our own? According to biologists, we could create custom-built chromosomes to fix a variety of health problems, and even give us new abilities. Here’s how a 24th pair of chromosomes could change our biologies forever.

To learn more about this incredible prospect, we spoke to biophysicist Gregory Stock. He is the Chief Science Officer of Ecoeos , a company that develops clinically-validated DNA tests to measure personal susceptibility to environmental toxins. Stock is also the author of Redesigning Humans: Choosing Our Genes, Changing Our Future , and the recently updated Book of Questions which is scheduled for release later this year.

But before we get into artificial human chromosomes (AHCs), let’s quickly review what chromosomes are in the first place.

Packages of Genetic Material

Chromosomes are packages of the genetic material located in our cells — the foundation of our basic biology as an organism. They’re not a recipe for us, but they do specify the sequence of events that lead to the development of mature organisms. Chromosomes offer a way for nuclear material to be packaged, protected, and maintained as it’s passed from cell to cell.

Different components of chromosomes are turned on and off in different contexts and in various parts of the body. There are anywhere from around 250 million bases on some chromosomes, down to about 50 million on others.

We humans have 23 pairs, for a total of 46. These structures are very tightly organized windings of DNA that become encoiled in a complicated way and allow for division each time a cell divides, so that each cell has the same complement of genetics.

There are two types: autosomal and sex chromosomes.

Sometimes, an added chromosome can be problematic. An extra chromosome 21 leads to trisomy, also known as Down syndrome. XXYY syndrome happens when males have an extra X and Y chromosome, leading to developmental delays, extra height, and learning disabilities.

Now With Added Function!

But adding extra chromosomes artificially won’t necessarily be a bad thing. And in fact, they could be quite advantageous. When inserted during the in vitro fertilization (IVF) stage, they could serve as remarkable and flexible platform for the insertion of genetics.

“The main attraction of creating an artificial human chromosome is that they can be passed down from generation to generation,” says Stock. “There’s all sorts of mechanisms and structures in place that would allow for the division and faithful reproduction of those chromosomes.”

What’s more, he explains, physicians will be able to control the various elements of the genetic sequences. We’ll be able to turn them on or off, or even accelerate their expression. Certain chromosomes may be put in place to serve as a backup, or to function at a specific stage of a person’s life (such as during elderly years when existing genetics isn’t up to the task).

Stock says we could add an additional pair, bumping our total up to 24. Or, if we wanted to deploy them in discrete and tidy packages — which would contribute greatly to their flexibility — we could just keep adding pair after pair after pair. In fact, the technology to do this could come sooner rather than later, with chromosomes containing a mere 10 to 20 megabases.

“Ideally, if you were to create an extra chromosome, rather than putting extra genetic material and inserting it into an existing chromosome — where it might be put into a random spot or put into something else that’s going on — you have a very controlled environment,” he told io9. “You can create these things, duplicate them independently, and put them in different organisms. It’s a very controlled process.”

And in fact, this is already being done. The prospect got off the ground back in 1997 after John Harrington and Huntington Willard developed a technique for doing so . Bacterial artificial chromosomes are used in labs all the time, as are yeast ACs (called YACs). Biologists have even created ACs in mice. We’re currently at the nascent stage of human artificial chromosomes .


This was quite a collaborative effort – as a group, what are your top tips for successful collaborations?

This was indeed a very fun collaboration across the globe. Here are some reasons why our collaboration worked so well:

  1. Our laboratory was in constant communication with other researchers, meeting frequently (in our case it was mostly virtual). This level of communication was critical, because our team was located in both Boston and Barcelona. Our emails were long and frequent, and our virtual meetings occurred nearly around the clock.
  2. We understood each other’s interests and contributions and truly cared about each other’s welfare. This made it easy, even enjoyable, to resolve differences of opinion.
  3. We shared comparable levels of passion and interest in the project.

Luckily for us, everyone on the project was highly motivated, and we all got along extremely well.


Synthetic Biology Explained

Synthetic biology is a new interdisciplinary area that involves the application of engineering principles to biology. It aims at the (re-)design and fabrication of biological components and systems that do not already exist in the natural world. Synthetic biology combines chemical synthesis of DNA with growing knowledge of genomics to enable researchers to quickly manufacture catalogued DNA sequences andassemble them into new genomes.

Improvements in the speed and cost of DNA synthesis are enabling scientists to design and synthesize modified bacterial chromosomes that can be used in the production of advanced biofuels, bio-products, renewable chemicals, bio-based specialty chemicals (pharmaceutical intermediates, fine chemicals, food ingredients), and in the health care sector as well.

What is the difference between synthetic biology and systems biology? How does genetic engineering fit in?

Systems biology studies complex natural biological systems as integrated wholes, using tools of modeling, simulation, and comparison to experiment. Synthetic biology studies how to build artificial biological systems, using many of the same tools and experimental techniques. The focus is often on taking parts of natural biological systems, characterizing and simplifying them, and using them as components of an engineered biological system.

Genetic engineering usually involves the transfer of individual genes from one microbe or cell to another synthetic biology envisions the assembly of novel microbial genomes from a set of standardized genetic parts that are then inserted into a microbe or cell.

What are some goals of synthetic biology?

Synthetic biologists are working to develop:

  • Standardized biological parts -- identify and catalog standardized genomic parts that can be used (and synthesized quickly) to build novel biological systems
  • Applied protein design -- re-design existing biological parts and expand the set of natural protein functions for new processes
  • Natural product synthesis -- engineer microbes to produce all of the necessary enzymes and biological functions to perform complex multistep production of natural products and
  • Synthetic genomics -- design and construct a ‘simple’ genome for a natural bacterium.

How does industrial biotechnology fit in?

Industrial biotechnology provides tools to enhance the natural mechanisms of biological processes to efficiently produce enzymes, chemicals, polymers, or even everyday products such as vitamins and fuel. Scientists have studied the genomes of microbes to identify biological processes that can replace chemical reactions to make new products, cleaner manufacturing operations, and reduce the number of production steps.

For example, by harnessing the natural power of enzymes or whole cell systems, and using sugars as the feedstock for product manufacturing, industrial biotech companies can work with nature to help us move from a petroleum-based economy to a “bio-based economy.”

Industrial biotechnology innovations are now successfully competing with and replacing traditional petrochemical manufacturing processes. Companies that adopt industrial biotechnology find they can cut costs, reduce pollution and their carbon footprint, and increasing profitability.

Industrial biotech scientists and companies have been utilizing forms of synthetic biology for years, including gene splicing, metabolic engineering and directed evolution. Microorganisms that are engineered are used in closed fermentation vats to produce the end products desired. Genetically enhanced microbes (GEMs) are regulated by the Toxic Substances Control Act.

Examples of synthetic biology companies:

Commercial firms that sell synthetic DNA (oligonucleotides, genes, or genomes) to users are DNA synthesis companies, including ATG:biosynthetics, Blue Heron Biotechnology, DNA 2.0, GENEART and Genomatica.

Leading consumer companies of the DNA that are building novel biological systems for bioproducts, biofuels, and the healthcare sector include Amyris Biotechnologies, Inc., Codexis, Genencor (A Division of Danisco), Life Technologies, Genomatica, Qteros, CODA Genomics, Modular Genetics, DNA2.0, Inc., Verdezyne, DSM, Myriant, Gevo, Inc., LS9, Inc., OPX Biotechnologies, Solazyme and Synthetic Genomics, Inc.

What are some synthetic biotechnology breakthroughs?

The 1970s and 1980s saw the emergence of genetic engineering for environmental purposes, such as bioremediation. A bacterium able to digest petroleum components was developed. In fact the first biotech patent was for a microorganism for cleanup of oil spills. In 2003, scientists at the J. Craig Venter Institute (JCVI) led by Drs. Smith, Hutchinson and Venter, built in vitro a fully synthetic PhiX174 chromosome in just 14 days and
published their results in the Proceedings of the National Academy of Sciences.

In December 2004, George M. Church of Harvard Medical School and Xiaolian Gio of the University of Houston announced that they had invented a new “multiplex” DNA synthesis technique that will eventually reduce the cost of DNA synthesis to 20,000 base-pairs per dollar.

Early in 2006, Dr. Jay Keasling, director of the Berkeley Center for Synthetic Biology, and three post-doctoral researchers discovered and re-engineered a yeast containing bacterial and wormwood genes into a chemical factory to produce a precursor to artemisinin for use as an inexpensive anti-malarial drug.

In June 2007, the JCVI developed genome transplantation methods to transform one type of bacteria into another type dictated by the transplanted chromosome and published their results in the journal Science.

In January 2008, the JCVI created the first synthetic bacterial genome, Mycoplasma genitalium JCVI-1.0, representing the largest man-made DNA structure (also published in Science). Genome transplantation, synthesis and assembly are essential enabling steps toward the ultimate goal of a fully synthetic, activated cell.

In 2010, scientists at the J. Craig Venter Institute (JCVI) announced the world’s first synthetic life form the single-celled organism based on an existing bacterium that causes mastitis in goats, but at its core is an entirely synthetic genome that was constructed from three chemicals in the laboratory. The single-cell organism has four “watermarks,” written into its DNA to identify it as synthetic.

It took the Venter Institute 15 years to complete this initial project. Much more work needs to be done before scientists can perfect techniques to synthesize novel genomes for microbes or cells.


13 Replies to &ldquoCan We Rejuvenate Our Bodies Using Telomerase to Lengthen Telomeres?&rdquo

The whole of the telomere story is a wonderful narrative of biology and scientific discovery. It is one of the deductive marvels of molecular and cellular biology. The chromosome end problem and the prediction of the existence and necessity of a “telomerase” activity in dividing cells emerged from Meselsohn and Stahl’s demonstration that DNA replication was semi-conservative as intuited from the awe of Watson and Crick’s base complementary double helix structure for DNA. The proof of the existence of telomerase by classical biochemistry led to another set of Nobel prizes. What a grand story in biology, and great for teaching new students in the life sciences how deductive reasoning and experimentation can integrate to define amazingly real features of living beings.

But after that, the story is more uncertain than the current deductive reasoning about the role of chromosome ends and telomerase in processes like cancer and aging. In the deductive process, one must pay close attention to hobgoblins that don’t fit into the general theory…and don’t forget about them as comfort with the conventional thinking grows. Okay, so below is a list of hobgoblins that stay on my mind to call into question the currently reigning concepts that reduced or lost telomerase contributes to human aging and activation of telomerase is an important factor in the initiation of cancers. Let me say here, though, that the experimental data are actually quite good to support the idea that mutations that increase or maintain telomerase activity can promote the progression of tumors. It’s the role of telomerase in the initiation of cancer cells and aging that I’m calling into question.

1. Let’s get back to the early experiments that were the basis for concluding that loss of telomerase activity is responsible for the senescence of primary mammalian cell cultures. My research teams’ work has suggested an alternative explanation, namely the serial dilution of asymmetrically self-renewing tissue stem cells by their progeny cells that have a limited division potential. Here’s the hobgoblin. The time at which a primary cell culture attains senescence depends greatly on how frequently and how much it is diluted during serial passage. No one has explained this well known property in terms of the telomerase hypothesis. It has been mostly ignored. Yet, it is easily explained by the dilution rate of asymmetrically self-renewing tissue stem cells, because stem cell asymmetric self-renewal has been shown to be cell density dependent.

2. The key tissue cell type for the proposed effects of telomere metabolism on aging and cancer is the asymmetrically self-renewing tissue stem cell. There are two hobgoblins here that are continuously overlooked. First because of the formidable problem of specific identification of tissue stem cells, their actual telomerase expression state remains largely imagined and actually unknown. Beware reports claiming to have made such crucial determinations. Always look carefully at either the purity of the “stem cells” examined and the basis for their designation as tissue stem cells. Second, given the existence of non-random immortal DNA strand co-segregation in asymmetrically self-renewing tissue stem cells, there is NO chromosome end problem! Telomerase becomes irrelevant for preventing DNA replication induced shortening, because new and old DNA strands are not randomly retained by the stem cells. Of course, telomerase might still join other chromosome end associated complexes to insure proper chromosome function, but this distinction could be very important to make for an accurate view of what is most responsible for initiation of aging and cancer.

Thank you so much, Dr. Sherley for adding that piece. You have shown how researchers are still stumbling in the dark on some aspects.


Kyk die video: Gen, hromatin, hromozomi (Oktober 2022).

1. A phenotypic male with one Barr body.