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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

JUMPING GENES AND IMMUNITY. "We found that ERVs have shaped the evolution of a transcriptional network underlying the interferon (IFN) response, a major branch of innate immunity, and that lineage-specific ERVs have dispersed numerous IFN-inducible enhancers independently in diverse mammalian genomes." (ERVs = endogenous retroviruses). https://lnkd.in/dn8M8m8 View in LinkedIn

ABUNDANT MOBILE ELEMENTS. "Endogenous retroviruses (ERVs) are abundant in mammalian genomes and contain sequences modulating transcription. The impact of ERV propagation on the evolution of gene regulation remains poorly understood." https://lnkd.in/dn8M8m8 View in LinkedIn

NET LOSS. "The loss of macromolecular constituents during plant tissue senescence is not associated with a concomitant rise in metabolite levels but rather with a decline in total carbon and nitrogen within the tissue. Indeed, the implied transport of metabolites out of the leaf has been substantiated in a number of cases." https://lnkd.in/dNWP3KD View in LinkedIn

GENETIC NOVELTY. "Transposable elements (TEs) are the key players in generating genomic novelty by a combination of the chromosome rearrangements they cause and the genes that come under their regulatory sway. Genome size, gene content, gene order, centromere function, and numerous other aspects of nuclear biology are driven by TE activity." https://lnkd.in/daec-Ac View in LinkedIn

SPARED UNTIL LAST. "Autolytic changes in the cell do not extend injtially to the mitochondria or nucleus, both of which remain unaffected until very late in the process of senescence." https://lnkd.in/dNWP3KD View in LinkedIn