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APPEARANCE OF HOMOLOGY. "As was recently demonstrated for the regulation of the floral homeotic gene AGAMOUS by orthologues of LEAFY in different flowering plants, variation in TF binding sites can simultaneously form the basis for conserved as well as divergent regulatory interactions, leading to novel phenotypes: observed changes in expression patterns that appear to be similar may not be caused by homologous genetic processes." (TF = transcription factors). https://lnkd.in/dD4GcAS View in LinkedIn

GENETIC SHUFFLING. "Besides mutations, viruses with segmented genomes change genetically through ‘genetic reassortment’. The latter term denotes the exchange of one or more genome segments between two related viruses which infect a host cell at the same time. During such a double infection the construction plans of both viruses become replicated in one host cell." https://lnkd.in/d8xM5QF View in LinkedIn

SUPER FAST EVOLUTION. "Three characteristics contribute to the rapid evolution of these viruses: large populations, short generation times and high mutation rates. Every mutation, which enables its carrier to evade the host’s immune system, will be (positively) selected, passed on to the next generation and distributed more widely. Influenza viruses evolve 1 million times faster than mammals. Five years of virus evolution roughly correspond to the time span, which separates humans and chimpanzees from their last common ancestor." https://lnkd.in/d8xM5QF View in LinkedIn

KEY FACTORS OF VIRUSES. "Most pathogens have large population sizes and short generation times. This is particularly true for viruses. The complete replication-cycle of a virus within a host cell often takes only a few hours and results in many thousands new viruses. Because the viral RNA-polymerase does not possess a proof-reading-function, faulty nucleotides are integrated during replication with a likelihood of 10(-3) to 10(-4), which results in high mutation rates. In fact, the error rate of the viral RNA-polymerase is 1000 times higher than the error rate of the human DNA- polymerase." https://lnkd.in/d8xM5QF View in LinkedIn

SO ENDS this consideration of the genetic drivers of flower shape. This was a difficult topic but hopefully worth it. Animals and plants differ significantly in their construction and underlying genetics, and the rampant gene duplication in plants appears to give a vast range of options for natural selection to act upon and allow considerable phenotypic diversity to emerge. View in LinkedIn

SILENT DUPLICATION EFFECTS. "Mutations in the coding regions of genes involved in a regulatory network can cause changes in protein–protein interactions, but these interactions could occur in a restricted, tissue-specific manner and impact a subset of developmental functions. The presence of duplicated genes means that mutations and subsequent drift or natural selection affecting genes or their targets can occur without necessarily changing the essential function of an existing GRN." (GRN = gene regulatory networks). https://lnkd.in/dD4GcAS View in LinkedIn

ONE PROPOSED LINK. "A new model published this week in The Journal of Chemical Physics, from AIP Publishing, proposes a potential mechanism by which self-replication could have emerged. It posits that template-assisted ligation, the joining of two polymers by using a third, longer one as a template, could have enabled polymers to become self-replicating." https://publishing.aip.org/publishing/journal-highlights/origins-life-new-model-may-explain-emergence-self-replication-early View in LinkedIn

MISSING LINK. "Or so the story goes. But with no fossil record to check from those early days, it's a narrative that still has some chapters missing. One question in particular remains problematic: what enabled the leap from a primordial soup of individual monomers to self-replicating polymer chains?" https://publishing.aip.org/publishing/journal-highlights/origins-life-new-model-may-explain-emergence-self-replication-early View in LinkedIn

THE DOGMA. "Then, somewhere along the line, these growing polymer chains developed the ability to make copies of themselves. Competition between these molecules would allow the ones most efficient at making copies of themselves to do so faster or with greater abundance, a trait that would be shared by the copies they made. These rapid replicators would fill the soup faster than the other polymers, allowing the information they encoded to be passed on from one generation to another and, eventually, giving rise to what we think of today as life." https://publishing.aip.org/publishing/journal-highlights/origins-life-new-model-may-explain-emergence-self-replication-early View in LinkedIn

SOME VIRTUES OF BOXES. "These molecular parasites would have been a major driver for the development of compartmentalization/cellularization, as more robust compartments could have outcompeted parasite-ridden compartments." http://pubs.acs.org/doi/abs/10.1021/ar200325v View in LinkedIn