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TWO EVENTS. “Phylogenetic analyses suggest that dioecy evolved once or potentially twice within a single clade in the Asparagus phylogeny, coincident with increases in genome size and repetitive DNA content, as well as a range expansion from southern Africa into northern Africa and Europe.” https://lnkd.in/gKA5C8N View in LinkedIn

Scientists replace skin of 'butterfly child' http://www.cnn.com/2017/11/10/health/skin-replacement-transplant-success/index.html View in LinkedIn

ASPARAGUS LANDSCAPE. “The genus Asparagus includes just over 200 species, the vast majority of which are hermaphrodites. Previous work has shown that dioecy arose within a single clade in the Asparagus phylogeny.” https://lnkd.in/gKA5C8N View in LinkedIn

SO ENDS this first weekend on the theme of viral dark matter. Physics is thwarted by the presence of a majority of the physical world being unknown dark matter. So with biology. But in the case of biology, we have adopted an ostrich pose to account for our ignorance, with an early focus only on disease, and a persistent and willful attitude that these are non-living (and thus irrelevant) entities. A few pioneers are trying to pull biologists out of the Dark Ages. View in LinkedIn

PRECEDENT DETAILS. “The experimental one-gene sex determination systems described for melon and maize, involve mutations in two genes, but it is the segregation of a single functional gene that ultimately determines sex.” https://lnkd.in/gKA5C8N View in LinkedIn

HOW MANY TYPES OF VIRUS EXIST is a different question from how many individual viral particles exist (10(31)). “At present only a small part of the total diversity of viruses has been studied, with analyses of samples from humans finding that about 20% of the virus sequences recovered have not been seen before, and samples from the environment, such as from seawater and ocean sediments, finding that the large majority of sequences are completely novel.” The large majority! https://lnkd.in/eF3wTsF View in LinkedIn

ASPARAGUS SEX GENE CONCLUSION. “The work done to date suggests that single-gene sex determination systems may evolve following fixation of null mutations in unlinked but interacting sex-specification genes, or as we show here for garden asparagus, two or more linked genes may act independently during development of female or male reproductive pathways.” https://lnkd.in/gKA5C8N View in LinkedIn

SEXUAL SYSTEM DIVERSITY. “Given the immense diversity in sexual systems across the angiosperms and numerous independent origins of dioecy, we expect different genetic factors will be regulating male and female function in unrelated dioecious lineages.” https://lnkd.in/gKA5C8N View in LinkedIn

EXAPTATION OF OLD GENES. “Taken together, the body of data presented here strongly supports that the evolution of an active Y chromosome in Asparagus was mediated by gene duplication and neofuntionalization of a female suppressor and subsequent expansion of the non-recombining sex determination region.” https://lnkd.in/gKA5C8N View in LinkedIn

MTF CONVERSION. “Dioecy has evolved recently within Asparagus and sex chromosomes are cytogenetically identical with the Y, harboring a megabase segment that is missing from the X. We show that deletion of this entire region results in a male-to-female conversion, whereas loss of a single suppressor of female development drives male-to-hermaphrodite conversion.” https://lnkd.in/gKA5C8N View in LinkedIn