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MATURE LEAVES. "In principle, natural selection is unlikelyto favor excessive energy investment in the maintenance of such an organ past the average time of its usefulness to the plant, because such an investment may compromise reproductive success." https://lnkd.in/dNWP3KD View in LinkedIn

LEAF FALL. "Timing of leaf abscission is an important trait for biomass production and seasonal acclimation in deciduous trees. The signaling leading to organ separation, from the external cue (decreasing photoperiod) to ethylene-regulated hydrolysis of the middle lamellae in the abscission zone, is only poorly understood." https://lnkd.in/dTkfjMD View in LinkedIn

FRAGMENT FROM NATURE continues from last weekend on the subject of autumn leaf drop. As plants harvest the invested nutritional value from autumn leaves before they drop them, there is a hive of genetic and metabolic activity within the forest; large numbers genes are turned on and off, triggered by environmental cues, while leaf molecules are being shunted to storage tissues to wait for the spring growth initiative. A busy time for our friends. View in LinkedIn

INESTIMABLY IMPORTANT EVENT. "It has been suggested that cyanobacteria raised oxygen levels in the atmosphere around 2.45–2.32 billion y ago during the Great Oxidation Event (GOE), hence dramatically changing life on the planet. The far-reaching impact of the GOE cannot be emphasized enough: it changed Earth’s history by enabling the evolution of aerobic life." http://www.pnas.org/content/110/5/1791.full View in LinkedIn

"CYANOBACTERIA are among the most diverse prokaryotic phyla, with morphotypes ranging from unicellular to multicellular filamentous forms, including those able to terminally (i.e., irreversibly) differentiate in form and function." http://www.pnas.org/content/110/5/1791.full View in LinkedIn

COINCIDENT PATHS. "Evolution of multicellularity coincided with increased diversification of cyanobacteria and the Great Oxidation Event." https://lnkd.in/dfzihDR View in LinkedIn

IMMUNE INNOVATION. "CRISPR-Cas9 deletion of a subset of these ERV elements in the human genome impaired expression of adjacent IFN-induced genes and revealed their involvement in the regulation of essential immune functions, including activation of the AIM2 inflammasome. Although these regulatory sequences likely arose in ancient viruses, they now constitute a dynamic reservoir of IFN-inducible enhancers fueling genetic innovation in mammalian immune defenses."(ERVs = endogenous retroviruses; IFN = interferon). https://lnkd.in/dn8M8m8 View in LinkedIn

UNIFYING HYPOTHESIS. "More generally, our results unify the role of group formation and genetic relatedness across multiple evolutionary transitions and provide an unmistakable footprint of how natural selection has shaped the evolution of life." http://www.sciencedirect.com/science/article/pii/S0960982213005678 View in LinkedIn

DISMEMBERING TEAM. "The hydrolysis of proteins and nucleic acids that accompanies senescence must be mediated by proteases and nucleases, respectively. Transaminases may function to shunt nitrogen into the most common mobile forms, glutamine and asparagine, and mobilization of lipids released from thylakoid membranes presumably requires conversion to sugars through the glyoxylate cycle." https://lnkd.in/dNWP3KD View in LinkedIn

CLONAL TRANSITIONS. "We found that species with clonal group formation were more likely to have undergone the major evolutionary transition to obligate multicellularity and had more cell types, a higher likelihood of sterile cells, and a trend toward higher numbers of cells in a group." http://www.sciencedirect.com/science/article/pii/S0960982213005678 View in LinkedIn