Parthenogenesis is asexual reproduction in which genetic contribution from male is dispensed with. Eggs develop to offspring on their own without being fertilised by a sperm. This is seen in nature in some species of plants, insects, reptiles etc. In facultative parthenogenesis the animal switch from sexual to parthenogenetic reproduction under difficult situations. Non-parthenogenetic species reproduce sexually and do not give “virgin births”. In a study reported recently, researchers achieved induction of facultative parthenogenesis and “virgin births” in Drosophila melanogaster (a non-parthenogenetic species) through γενετική engineering. The research team identified involved genes and demonstrated for the time first time how expressions of involved genes influence induction of facultative parthenogenesis in an animal.
Η παρθενογένεση είναι μια μορφή ασεξουαλικής αναπαραγωγής που δεν περιλαμβάνει γονιμοποίηση of an egg by a sperm. The embryo is formed by the female on her own (without γενετική contribution from a male) which develops to give “virgin birth”. Parthenogenesis could be either obligate or facultative. In case of facultative parthenogenesis, the animal switch from sexual to parthenogenetic reproduction under difficult situations while obligate parthenogenesis is the situation when reproduction is mainly asexual through parthenogenesis.
Οι «παρθενογέννητες» χωρίς γονιμοποίηση με σπέρμα μπορεί να ακούγονται περίεργες, αλλά αυτή η μορφή αναπαραγωγής στην οποία παραχωρείται το αρσενικό εμφανίζεται φυσικά σε πολλά είδη φυτών, εντόμων, απαντήσεων κ.λπ. προκλήθηκε τεχνητά στα αυγά στο εργαστήριο για να γεννήσει απογόνους βατράχων και ποντικών. Αυτές οι περιπτώσεις τεχνητής παρθενογένεσης σε βάτραχο και ποντίκια δεν έκαναν τους θηλυκούς βάτραχους και τα ποντίκια να μπορούν να γεννήσουν μόνα τους παρθενογένεση, καθώς μόνο τα αυγά τους προκλήθηκαν να υποστούν εμβρυογένεση στις εργαστηριακές συνθήκες. Αυτό έχει αλλάξει τώρα με την έκθεση (δημοσιεύτηκε στις 28th July 2023) of non-parthenogenetic animals giving “virgin births” following γενετική engineering. This is first such case of sexually reproducing animal turning parthenogenetic because of manipulations in their genes.
Two species of Drosophila were used in this study. Drosophila mercatorum species, which has sexually reproducing strain and parthenogenetically reproducing strain (facultative), was used to identify genes involved in parthenogenesis while Drosophila melanogaster which is a non-parthenogenetic species was used for gene manipulation to produce παρθενογενετική πετώ.
The research team sequenced genomes of two strains of Drosophila mercatorum and compared gene activity in eggs of the two strains. This led to identification of 44 candidate genes with potential roles in parthenogenesis. Next was to test if manipulating candidate gene homologs would induce facultative parthenogenesis in Drosophila melanogaster. The researchers found a polygenic system – facultative parthenogenesis in Drosophila melanogaster (a non-parthenogenetic species) was triggered by increased expression of the mitotic protein kinase polo and decreased expression of a desaturase, Desat2 that was enhanced by increased expression of Myc. The eggs grew parthenogenetically mainly to triploid offspring. This is first demonstration of γενετική basis of facultative parthenogenesis in an animal as well as its induction through γενετική μηχανική.
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Πηγές:
- Sperling AL, et αϊ 2023. Ο γενετική basis for facultative parthenogenesis in Drosophila. Current Biology Published: 28 July 2023. DOI: https://doi.org/10.1016/j.cub.2023.07.006
- University of Cambridge 2023. Ειδήσεις- Επιστήμονες ανακαλύπτουν το μυστικό της παρθενικής γέννησης και ενεργοποιούν την ικανότητα στις θηλυκές μύγες. Διαθέσιμο στο https://www.cam.ac.uk/research/news/scientists-discover-secret-of-virgin-birth-and-switch-on-the-ability-in-female-flies Πρόσβαση στις 2023-08-01.
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