Monelle evoluutiouskovaiselle viimeinen oljenkorsi evoluution todistamiseksi on ns. neofunctionalization, eli solun tapahtumaketju, jossa geeni saa uuden toiminnallisuuden duplikoitumisen jälkeen ja joka on yhteydessä johonkin uuteen solun toiminnallisuuteen. Ilmiö perustuu epigeneettisiin mekanismeihin, eikä se siis luo uutta informaatiota tai uusia rakenteita/toiminnallisuutta. Kyse on epigeneettisestä UUDELLEENOHJELMOINNISTA:
https://advances.sciencemag.org/content/5/7/eaaw7006
"Furthermore, sex change involves distinct epigenetic reprogramming and an intermediate state with altered epigenetic machinery expression akin to the early developmental cells of mammals."
"Together, this indicates that like H3K27 modification, there is an intense period of DNA methylation reprogramming in the gonad at intermediate stages of sex change. Such distinct sex-specific expression of DNA methyltransferase genes and other epigenetic modifiers was also recently observed in gonadal transcriptomes of other sex-changing fishes (37) and may be important for sexual plasticity."
"Transcriptomic and methylome analyses across sex change in the iconic bluehead wrasse have identified the triggers of socially induced sex change and enactors of gonadal metamorphosis. Our results suggest that the environmental stimulus is exerted via stress, that the subsequent steps involve repression of aromatase, and that distinctive epigenetic reprogramming is associated with reengineering ovaries into testes (Fig. 7). Importantly, this does not occur by direct transdifferentiation but involves an intermediate state with altered epigenetic machinery expression that is reminiscent of mammalian naïve pluripotent stem cells and PGCs."
"Gene neofunctionalization following duplication allows for diversification of a standard genetic network and may be one factor contributing to the sexual plasticity that is characteristic of fishes."
"The use of neofunctionalized paralogs in sex change was not restricted to hormonal and signaling pathways; we also found duplicated epigenetic machinery in bluehead wrasses that exhibited female- or male-specific expression. Global DNA methylation was remodeled, as expression of female-specific DNMTs was replaced with male-specific expression. The peak in TET expression seen at this time indicates remodeling of DNA methylation that is typical of mammalian PGCs and both naïve and classically grown pluripotent stem cells (30). The same appeared to be true for histone-modifying machinery; the PRC2 complex is associated with differentiation in mammals and showed high expression in cells belonging to committed sexual phenotypes but was deactivated in the gonads of transitional fish. Likewise, dynamic expression of histone demethylases, acetyltransferases, and variant histones further suggest active chromatin modification during gonadal sex change."
Stressi, jota sinipäähuulikaloille aiheuttaa esim. niukka ravinto tai koiraiden/naaraiden määrän epätasapaino, johtaa niillä epigeneettiseen säätelyyn, joka voi ilmetä sukupuolen vaihdoksena naaraasta koiraaksi. Ilmiö on puhtaasti epigeneettisten mekanismien ja tekijöiden ohjaama uudelleenohjelmointiprosessi. Tässäkin prosessissa DNA on vain passiivista informaatiovarantoa ja epigeneettiset mekanismit voivat tuottaa jopa geeniduplikaatioita, jotta tarvittavat sukupuoleen liittyvät toiminnallisuudet saadaan toteutettua.
Taas kerran on kumottu evoluutiouskovaisten väitteet satunnaisista mutaatioista ja valinnasta ym. hölynpölystä. Evoluutiota ei ole koskaan tapahtunut.
https://advances.sciencemag.org/content/5/7/eaaw7006
"Furthermore, sex change involves distinct epigenetic reprogramming and an intermediate state with altered epigenetic machinery expression akin to the early developmental cells of mammals."
"Together, this indicates that like H3K27 modification, there is an intense period of DNA methylation reprogramming in the gonad at intermediate stages of sex change. Such distinct sex-specific expression of DNA methyltransferase genes and other epigenetic modifiers was also recently observed in gonadal transcriptomes of other sex-changing fishes (37) and may be important for sexual plasticity."
"Transcriptomic and methylome analyses across sex change in the iconic bluehead wrasse have identified the triggers of socially induced sex change and enactors of gonadal metamorphosis. Our results suggest that the environmental stimulus is exerted via stress, that the subsequent steps involve repression of aromatase, and that distinctive epigenetic reprogramming is associated with reengineering ovaries into testes (Fig. 7). Importantly, this does not occur by direct transdifferentiation but involves an intermediate state with altered epigenetic machinery expression that is reminiscent of mammalian naïve pluripotent stem cells and PGCs."
"Gene neofunctionalization following duplication allows for diversification of a standard genetic network and may be one factor contributing to the sexual plasticity that is characteristic of fishes."
"The use of neofunctionalized paralogs in sex change was not restricted to hormonal and signaling pathways; we also found duplicated epigenetic machinery in bluehead wrasses that exhibited female- or male-specific expression. Global DNA methylation was remodeled, as expression of female-specific DNMTs was replaced with male-specific expression. The peak in TET expression seen at this time indicates remodeling of DNA methylation that is typical of mammalian PGCs and both naïve and classically grown pluripotent stem cells (30). The same appeared to be true for histone-modifying machinery; the PRC2 complex is associated with differentiation in mammals and showed high expression in cells belonging to committed sexual phenotypes but was deactivated in the gonads of transitional fish. Likewise, dynamic expression of histone demethylases, acetyltransferases, and variant histones further suggest active chromatin modification during gonadal sex change."
Stressi, jota sinipäähuulikaloille aiheuttaa esim. niukka ravinto tai koiraiden/naaraiden määrän epätasapaino, johtaa niillä epigeneettiseen säätelyyn, joka voi ilmetä sukupuolen vaihdoksena naaraasta koiraaksi. Ilmiö on puhtaasti epigeneettisten mekanismien ja tekijöiden ohjaama uudelleenohjelmointiprosessi. Tässäkin prosessissa DNA on vain passiivista informaatiovarantoa ja epigeneettiset mekanismit voivat tuottaa jopa geeniduplikaatioita, jotta tarvittavat sukupuoleen liittyvät toiminnallisuudet saadaan toteutettua.
Taas kerran on kumottu evoluutiouskovaisten väitteet satunnaisista mutaatioista ja valinnasta ym. hölynpölystä. Evoluutiota ei ole koskaan tapahtunut.
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