"Our discussion begins by considering life without the human gut microbiome, follows with a hypothetical scenario of a world without Bacteria and Archaea, and concludes with the implications of a world without all microbes, including microbial eukaryotes and viruses. We do not include the organelles, such as mitochondria and chloroplasts, as microbes in our discussion, simply because most eukaryotic life would cease instantly in their absence."
Mary Williams's insight:
Good short read. What was the first process you thought of that would stop without microbes? I thought of nitrogen fixation. The authors argue that to some extent the Haber-Bosch process could substitute for the missing microbes, but not optimally.
"This tuber contains high amounts of vitamin E, which may protect lipids from free radical attack and lower the levels of lipid peroxidation. This, together with the capacity to grow slowly, but continuously, presumably helps to prevent senescence at the organism level. Reduced growth and high longevity (compared with other herbs) make this geophyte unique within the tree of life, and at least partially explain the evolutionary success of B. pyrenaica from the Tertiary to date. This success involves surviving changes in climatic conditions, presumably by being somewhat protected underground. The present study further supports the notion that this plant species shows negative senescence and that its mortality may be explained by factors different from ageing." (Thanks to Christophe Jacquet for alerting me to the paper)
"We show that transient calcium-dependent interactions of PYR/PYL ABA receptors with membranes are mediated through a 10-member family of C2-domain ABA-related (CAR) proteins in Arabidopsis thaliana. Specifically, we found that PYL4 interacted in an ABA-independent manner with CAR1 in both the plasma membrane and nucleus of plant cells. CAR1 belongs to a plant-specific gene family encoding CAR1 to CAR10 proteins, and bimolecular fluorescence complementation and coimmunoprecipitation assays showed that PYL4-CAR1 as well as other PYR/PYL-CAR pairs interacted in plant cells. The crystal structure of CAR4 was solved, which revealed that, in addition to a classical calcium-dependent lipid binding C2 domain, a specific CAR signature is likely responsible for the interaction with PYR/PYL receptors and their recruitment to phospholipid vesicles."
What an interesting study! PNAS publishes it under the categories of Ethnobotany and Folk Taxonomy. One of the important messages it conveys is that "Most of the Africans who arrived in the Americas were already skilled farmers and came from cultures considerably practiced in using local flora and fauna" and it "reveals the frequency with which enslaved Africans recognized familiar taxa but also show their detailed botanical knowledge."
Leaf development is such a fascinating topic, because it reveals the molecular processes the are involved in pattern formation. Interestingly, several genes and small molecules (e.g., auxin) are used repeatedly during the initiation and elaboration of leaves. A pair of papers out in Plant Cell highlights this thrifty genetic strategy. In the first, we see how the development of the ligule in a maize leaf involves the redeployment of several genes that are involved in leaf initiation, a process that occurs much earlier in the developmental pathway.
Transcriptomic Analyses Indicate That Maize Ligule Development Recapitulates Gene Expression Patterns That Occur during Lateral Organ Initiation (www.plantcell.org/…/early/2014/12/16/tpc.114.132688.abstract). In the second, we see the KNOX1 / GA module that is so important in leaf developmental patterning also contributes to the environtmental responsiveness of leaf shape (heterophylly), as found in aquatic plants such as Rorippa aquatica. Regulation of the KNOX-GA Gene Module Induces Heterophyllic Alteration in North American Lake Cress (http://www.plantcell.org/…/20…/12/16/tpc.114.130229.abstract). These studies also reinforce our understanding of process of evolution; why start from scratch when you can just tweak something that aleady works in another context?
"Whereas the downstream signaling cascades and biological consequences have been described, the initial events that underpin photochemistry of the coupled bilin chromophore and the ensuing conformational changes needed to propagate the light signal are only now being understood. Especially informative has been the rapidly expanding collection of 3D models developed by x-ray crystallographic, NMR, and single-particle electron microscopic methods from a remarkably diverse array of bacterial Phys. These structures have revealed how the modular architecture of these dimeric photoreceptors engages the buried chromophore through distinctive knot, hairpin, and helical spine features."