Polar lipids and pigments as biomarkers for the study of the microbial community structure of solar salterns

Whole community lipids and pigments have been examined over a 3–5-year period in commercial salterns located in the United States, Israel, and Spain. There were significant differences in the types of lipids and pigments within the California saltern system during the 5-year period. These patterns differed seasonally despite examination of ponds with approximately the same salinities. The solar saltern in Eilat, Israel had fewer lipids on the thin-layer chromatography plates and confirmed previous analyses. The biota in the crystallizer pond in Alicante, Spain, resembled the microbial community in Israel. In the crystallizers at all three locations, phosphatidyl glycerol, methyl-phosphatidyl glycerophosphate, phosphatidyl glycerosulfate, and the sulfated diglycosyldiether lipid were identified regardless of season. This was not true for pans with salinities below 25% where no distinctive pattern was observed. Thus, we hypothesize that the more eutrophic inlet waters of the California saltern and the cooler temperatures, which result in longer retention times of water in the different pans, allow for the more diverse microbial community to develop. This is reflected then in more complex lipid and pigment patterns. However, the oligotrophic inlet waters to the Eilat saltern coupled with a drier and warmer climate result in a shorter retention time of water in the pans and a less diverse microbial community as evidenced by fewer extractable lipids and pigments.     

CloneSeq: A highly sensitive analysis platform for the characterization of 3D-cultured single-cell-derived clones

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Bioenergetic Aspects of Halophilism

Examinination of microbial diversity in environments of increasing salt concentrations indicates that certain types of dissimilatory metabolism do not occur at the highest salinities. Examples are methanogenesis for H₂ + CO₂ or from acetate, dissimilatory sulfate reduction with oxidation of acetate, and autotrophic nitrification. Occurrence of the different metabolic types is correlated with the free-energy change associated with the dissimilatory reactions. Life at high salt concentrations is energetically expensive. Most bacteria and also the methanogenic archaea produce high intracellular concentrations of organic osmotic solutes at a high energetic cost. All halophilic microorganisms expend large amounts of energy to maintain steep gradients of NA⁺ and K⁺ concentrations across their cytoplasmic membrane. The energetic cost of salt adaptation probably dictates what types of metabolism can support life at the highest salt concentrations. Use of KCl as an intracellular solute, while requiring far-reaching adaptations of the intracellular machinery, is energetically more favorable than production of organic-compatible solutes. This may explain why the anaerobic halophilic fermentative bacteria (order Haloanaerobiales) use this strategy and also why halophilic homoacetogenic bacteria that produce acetate from H₂ + CO₂ exist whereas methanogens that use the same substrates in a reaction with a similar free-energy yield do not.     

Phosphorylation-mediated stabilization of Bora in mitosis coordinates Plx1/Plk1 and Cdk1 oscillations

Cdk1 and Plk1/Plx1 activation leads to their inactivation through negative feedback loops. Cdk1 deactivates itself by activating the APC/C, consequently generating embryonic cell cycle oscillations. APC/C inhibition by the mitotic checkpoint in somatic cells and the cytostatic factor (CSF) in oocytes sustain the mitotic state. Plk1/Plx1 targets its co-activator Bora for degradation, but it remains unclear how embryonic oscillations in Plx1 activity are generated, and how Plk1/Plx1 activity is sustained during mitosis. We show that Plx1-mediated degradation of Bora in interphase generates oscillations in Plx1 activity and is essential for development. In CSF extracts, phosphorylation of Bora on the Cdk consensus site T52 blocks Bora degradation. Upon fertilization, Calcineurin dephosphorylates T52, triggering Plx1 oscillations. Similarly, we find that GFP-Bora is degraded when Plk1 activity spreads to somatic cell cytoplasm before mitosis. Interestingly, GFP–Bora degradation stops upon mitotic entry when Cdk1 activity is high. We hypothesize that Cdk1 controls Bora through an incoherent feedforward loop synchronizing the activities of mitotic kinases.     

Cell-Type-Specific Immune Dysregulation in Severely Ill COVID-19 Patients

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Induction of water-stress proteins in cyanobacteria exposed to matric- or osmotic-water stress

Abstract: Specific stress polypeptides were detected in three drought-resistant cyanobacteria ( Phormidium autumnale , LPP₄ and Chroococcidiopsis sp.) subjected to matric- and osmotic-water stress. Drought stress caused the induction of at least 2–3 new polypeptides of apparent molecular masses of 30 kDa and 40–45 kDa. The polypeptide of 30 kDa was located in the thylakoid membranes, and the 45-kDa polypeptide in the cytoplasm. When these cyanobacteria were exposed to salt stress polypeptides of similar size appeared.     

Hydrolysis of N'-benzoyl-d-arginine-p-nitroanilide by members of the Haloanaerobiaceae: additional evidence that Haloanaerobium praevalens is related to endospore-forming bacteria

Abstract Three out of the four described halophilic obligately anaerobic bacteria of the family Haloanaerobiaceae hydrolyze d -BAPA (N'-benzoyl- d -arginine-p-nitroanilide), while showing no or little l -BAPA hydrolyzing activity. This property was shown earlier to be characteristic only of non-halophilic Gram-positive endospore-forming bacteria of the genera Bacillus and Clostridium . These results suggest that Haloanaerobium praevalens , which has never been shown to produce endospores, but was shown to be related to the endosphere-forming representatives of the Haloanaerobiaceae on the basis of 16S rRNA nucleotide sequence data, shares other properties characteristics of the endospore-forming bacteria. Neither significant d -BAPA nor l -BAPA hydrolyzing activity was found in Sporohalobacter lortetii .