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FLORAL DIVERSITY. "Any survey of floral diversity will reveal that much of the morphological variation does not occur in aspects of floral organ identity but in other features, such as the arrangement of the organs within the meristem (phyllotaxy), the number of organs of each type (merosity), the elaboration of the floral organs (e.g., organ fusion), and floral symmetry." https://lnkd.in/dVXk7jP View in LinkedIn

FLOWERING PLANTS. "The 240,000-plus species of angiosperms that now dominate most of Earth's terrestrial ecosystems were derived from a series of major radiations, starting with their enigmatic appearance approximately 130 million years ago." https://lnkd.in/dVXk7jP View in LinkedIn

SEPAL AND PETAL ORIGINS. "The situation for sepal and petal identity is much more complicated, however, possibly reflecting the fact that these organ types may have evolved independently in different angiosperm lineages." https://lnkd.in/dVXk7jP View in LinkedIn

FRAGMENT FROM NATURE for this and next weekend dabbles into flower structure over space and time, and touches on their genetic regulation. Perhaps among the most admired highly diverse organs, flower structural transformations cross geometric axes, sexual axes, often fusing disparate organ systems into new forms, in a seemingly endless quest for innovation. View in LinkedIn

HIGHER COMPLEXITY FROM SIMPLE BASE. "The protein products of these genes function in combination as dimers that may further interact with one another to form higher-order protein complexes. In evolutionary terms, many aspects of what is now termed the ABCE model are deeply conserved across the angiosperms, most notably the stamen and carpel identity pathways." https://lnkd.in/dVXk7jP View in LinkedIn

HALLMARK OF MEIOSIS. "A key innovation—indeed, the hallmark of meiosis—was synapsis between homologs." https://lnkd.in/ebVhXPf View in LinkedIn

SURVIVAL MECHANISM. "Notably, other types of DNA lesions, such as abasic sites or nicks generated by DNA deaminase acting to convert cytosine to uracil (a substrate for uracil N-glycosylase), can restore meiotic recombination in mutants of the fission yeast Schizosaccharomyces pombe lacking Spo11 (rec12) without generating double strand breaks." https://lnkd.in/ebVhXPf View in LinkedIn

COMPETITIVE ADVANTAGE. "Such a model is supported by the finding that the meiotic defects of S. cerevisiae spo11 mutants can be in part suppressed by gamma irradiation, suggesting that random double strand breaks can suffice to enhance meiotic crossovers and increase spore viability and germination." http://cshperspectives.cshlp.org/content/6/3/a016154.full View in LinkedIn

HYPOTHESIS. "Perhaps the most interesting hypothesis for why replication occurs before meiotic recombination in meiosis I is that in the pre-Spo11 era, the sister-chromatid copies served as the source of double strand breaks. Double strand breaks are formed by replication of nicked DNA, in which the nicks might have been incurred by UV or gamma rays before Spo11, and double strand breaks (but not nicks) are potent stimulators of homologous recombination." https://lnkd.in/ebVhXPf View in LinkedIn

MEIOSIS INNOVATION (4) "Homolog synapsis and the persistence of sister-chromatid cohesion through meiosis I into meiosis II." http://cshperspectives.cshlp.org/content/6/3/a016154.full View in LinkedIn