#gene

#gene

Female Salamanders Upend What We Know About ReproductionA line of salamanders of the Ambystoma genus are all female. They produce all female offspring, and have been doing that for millions of years. Yet their offspring are not clones, even if their mitochondrial DNA is always the same. These salamanders mate with males from other species of the same genus, and incorporate their genetic material into the next generation of females. The scientists who studied this phenomenon call it “kleptogenesis” as it involves stealing genetic material from a different species. The unisex Ambystoma are weirder by far than other animals that are made up of only females. In some other female-only species, the females mate with related species because sperm kickstarts the process, then they reject all the males' DNA. In this salamander, the mother picks and chooses which parts of the male's genome will be incorporated into her female offspring. If she has mated with three males, she can incorporate the genes of one, or two, or three of them into her offspring, plus her own, or possibly delete her own, or use any combination of the reproductive DNA she has available. While this hybridization keeps the gene pool fresh, it does not change their reproductive behavior, not does it ever introduce males into the line. If this sounds complicated, it is. The research paper, with its biology jargon, is even more confusing, but you can read a relatively simple description of just how weird these unisexual salamanders are when it comes to their designer babies at Popular Science. -via Metafilter #salamander #reproduction #DNA #gene #kleptogenesis

All Identical Twins Carry a Common Factor in their GenesIdentical twins are produced when a fertilized egg or zygote divides completely in two and forms two separate individuals. The two will therefore have identical DNA. But scientists have found something that twins have notably in common with not only each other, but with other identical twins, even those they are not related to otherwise. And this trait does not appear in people who aren't identical twins. Scientists looking into the cause of twinning took a look at epigenetic factors. These are things that could cause a gene to be switch on or off, because not all genes are read by the cells they inhabit. A new study looked into methyl groups, that is, molecules that stick to genes and keep them from being expressed. Which genes these methyl groups stick to can form a pattern. A study of 6000 people, including identical twins, fraternal twins, and non-twin family members, shows that all the identical twins had the same methyl group pattern that covered 834 genes, while other participants did not. Whether this pattern is the cause of the embryonic split or not is still unclear. It's possible the split itself caused the pattern, or possibly the pattern somehow came from something unique in the prenatal environment of identical twins. However, scientists suspect that the methyl group pattern may cause the formation of identical twins, as many of the genes affected are those that govern how cells stick to each other. The research shows that this pattern is quite stable over the lifetime of an individual, but we don't yet know if it has any effect on a twin's physiology after birth. There are many more zygotes that split into identical twins than there are twins born. Often, one of the twins will stop developing and vanish before birth, without the mother ever knowing about it. From this study, one would think it might be possible to find out if a person had a vanished twin before birth by scanning for this methyl group pattern. But that research has yet to be done. Read about this breakthrough study in epigenetics at Live Science. -via Damn Interesting#twin #identicaltwin #gene #epigenetic 