July 28, 2023

expert reaction to study looking at a genetic basis for parthenogenesis, ‘virgin birth’, in Drosophila fruit flies

A study published in Current Biology looks at a genetic basis for facultative parthenogenesis in Drosophila.

Prof Petra Hajkova, Professor of Developmental Epigenetics, MRC Investigator, Medical Research Council London Institute of Medical Sciences, said:

“There is a fundamental difference between the reproduction in fruit flies and mammals (including humans) due to the existence of genomic imprinting.  This phenomenon, discovered by Surani and Solter back in 1984, documented that mammalian egg and sperm carry differential (sex specific) epigenetic marking.  Correct combination of maternal and paternal marks is required for a normal embryonic development and postnatal physiology.

“Genomic imprinting is fundamental to mammalian development and provides an effective barrier to parthenogenesis (virgin birth).  This barrier does not exist in fruit flies and in fact, as documented by the current work, some fly species can naturally reproduce through parthenogenesis.

“In the mouse work published last year documenting generation of the viable offspring from a single oocyte (https://www.pnas.org/doi/full/10.1073/pnas.2115248119) the authors used epigenetic editing (engineered mouse where they could induce specific epigenetic changes) to remedy incorrect genomic imprinting caused by the absence of paternal DNA.”

Dr Hannah Maude, Research Associate, Regulatory Genomics & Metabolic Disease, Department of Metabolism, Digestion & Reproduction, Imperial College London, said:

“This is first and foremost a research paper which offers important insight into mechanisms of “parthenogenetic reproduction”, or “virgin birth” which occurs in certain strains of fruit fly (Drosophila mercatorum).  The authors not only identify underlying mechanisms but demonstrate that altering them can induce virgin birth in strains of fruit fly which reproduce sexually.

“For those wondering if the same would be true of humans, the answer is probably not.  Our diversity protects us: having two copies of the DNA not only provides a back-up for harmful DNA variants (found in every person) but is necessary for so called imprinted regions which are specifically active from the maternal or paternal DNA copy.  Nevertheless, this exciting research furthers our understanding of reproduction in the animal kingdom.”

Dr Herman Wijnen, Associate Professor of Biological Sciences, University of Southampton, said:

“This new study shows that very limited genetic changes can have a lasting effect on enabling virgin births in fruit flies through successive generations.  The genes that were manipulated in the fruit fly are ones that are shared with humans, but there are substantial differences between early development in flies and humans.  Notably fly nuclei divide 13 time before they are physically separated from each other into different cells whereas nuclei remain separated after fertilization in human embryos.  Also, Drosophila fruit flies lack some of the DNA methylase enzymes important for restricting virgin births in humans and mice.  The fruit fly study is exciting because it demonstrates how parthenogenesis can evolve in a sexually reproducing species as a back-up strategy for females that are unable to find a partner.  The ease of manipulating genes and the ability to then test many individual offspring in the fruit fly system made this work possible.”

‘A genetic basis for facultative parthenogenesis in Drosophila’ by Alexis L Sperling et al. will be published in Current Biology at 16:00 UK time on Friday 28 July 2023.

DOI: 10.1016/j.cub.2023.07.006

Declared interests

Dr Hannah Maude: “None.”

For all other experts, no reply to our request for DOIs was received.