Year: 2022

DOSAGE. "Differentiated sex chromosomes in mammals and other vertebrates evolved independently but in strikingly similar ways. Vertebrates with differentiated sex chromosomes share the problems of the unequal expression of the genes borne on sex chromosomes, both between the sexes and with respect to autosomes. Dosage compensation of genes on sex chromosomes is surprisingly variable — and can even be absent — in different vertebrate groups." https://lnkd.in/gWDQizV View in LinkedIn

SIMILAR MODULES. "Systems that compensate for different gene dosages include a wide range of global, regional and gene-by-gene processes that differ in their extent and their molecular mechanisms. However, many elements of these control systems are similar across distant phylogenetic divisions and show parallels to other gene silencing systems." https://lnkd.in/gWDQizV View in LinkedIn

ANCIENT SILENCING MODULES. "These dosage systems cannot be identical by descent but were probably constructed from elements of ancient silencing mechanisms that are ubiquitous among vertebrates and shared throughout eukaryotes." https://lnkd.in/gWDQizV View in LinkedIn

NO COMBINATION. "It is well understood that the idea that sex-determining genes should not recombine can explain the lack of recombination between X and Y chromosomes of animals such as Drosophila and mammals with male heterogamety (or Z and W in taxa with female heterogamety such as birds and Lepidoptera." https://lnkd.in/gCh5RAX View in LinkedIn

GENE LOSS. "It is also well established that such nonrecombining Y or W chromosomes have lost many genes that are carried on the ancestrally homologous X or Z chromosomes (genetic degeneration." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

VIRAL BITS. "In many organisms, the sex chromosome pair can be recognized due to heteromorphy; the Y and W chromosomes have often lost many genes due to the absence of recombination during meiosis and are frequently heterochromatic. Repetitive sequences are found at a high proportion on such heterochromatic sex chromosomes and the evolution and emergence of sex chromosomes has been connected to the dynamics of repeats and transposable elements." https://lnkd.in/gMXukbs View in LinkedIn

ANCIENT VIRUSES AND SEX. “Our results highlight the role of TEs in the initial steps of differentiation and evolution of sex chromosomes.” (TE = transposable elements). https://lnkd.in/gMXukbs View in LinkedIn

1,516 mass shootings in 1,735 days: America's gun crisis – in one chart https://www.theguardian.com/us-news/ng-interactive/2017/oct/02/america-mass-shootings-gun-violence?CMP=Share_iOSApp_Other View in LinkedIn

HOMOLOGS. "In mammals, only a few X-linked genes have homologues on the Y chromosome, and several Y-linked genes are known that do not have homology to X-linked genes and have presumably been translocated to the Y from elsewhere; in D. melanogaster, all known Y-linked genes are in this latter category." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

VARIABLE. "Two main sex chromosome systems can be found in vertebrates with genetic sex determination: XX/XY (in which males are heterogametic) and ZZ/ZW (with heterogametic females). Nevertheless, sex chromosomes are extraordinarily variable, and other combinations also can be found, ranging from female heterogamety with 00/0W or ZZ/Z0 sex chromosomes to male heterogamety with XX/X0 sex chromosomes. Furthermore, complex XY and ZW systems are possible when fusions, fissions, and translocations between sex chromosomes and autosomes take place (e.g., X1X2Y, XY1Y2, or Z1Z2W)." https://lnkd.in/gvD548n View in LinkedIn