Identification of bacterial chemoattractants for oyster (Crassostrea virginica) hemocytes

The cytoplasmic and cell wall components of the Gram-positive bacterium Bacillus megaterium and the cytoplasmic and cell envelope components of the Gram-negative bacterium Escherichia coli were assayed for chemotactic activity for the hemocytes of Crassostrea virginica. The cellular components were separated by differential centrifugation and gel filtration was used to determine the approximate molecular weights of the chemoattractant molecules. Active fractions were assayed for glycoproteins and lipoproteins. As a result, it is known that hemocytes are chemotactically attracted to proteins of approximately 10,000 daltons which are associated with the cell wall of B. megaterium and the cell envelope of E. coli.     

Effect of glucose on protein phosphorylation in rat pancreatic islets

Isolated rat pancreatic islets, incubated in the presence of extracellular ³²Pi to steady state ³²P incorporation into cellular phosphopeptides, were exposed to glucose for 10 min. Glucose (16.7 mM) significantly stimulated the phosphorylation of six phosphoproteins with molecular weights of 15,000, 35,000, 49,000, 64,000, 93,000 and 138,000. Mannoheptulose (16.7 mM) markedly inhibited glucose-stimulated phosphorylation of these six phosphoproteins. This protein phosphorylation might be important in mediating glucose-stimulated insulin release.     

Hemocytes of Bulinus truncatus rohlfsi (Mollusca: Gastropoda)

Two basic cell types occur in the hemolymph of Bulinus truncatus rohlfsi: granulocytes and hyalinocytes. Granulocytes are divided into three subtypes: (1) Granulocytes I, which account for 19% of the hemocytes, are small, young amoebocytes with 1–20 filopodia and small numbers of cytoplasmic granules, including some lysosomes; (2) granulocytes II, which account for 78% of the cells, are large, fully developed amoebocytes that possess 1–20 filopodia and many granules, both acidophilic and basophilic, including numerous lysosomes, phagosomes, and mitochondria; and (3) spent granulocytes, which are rare, have few filopodia, large accumulations of glycogen granules and prominent vacuoles in addition to lysosomes in the cytoplasm. These three subtypes of granulocytes probably represent ontogenetic stages within a single cell line. In addition, granulocytes with 40 or more filopodia and little ectoplasm, found in only 1 of 45 snails examined, probably reflect a pathologic condition. Hyalinocytes, which account for 3% of all hemocytes, are similar in size to mature granulocytes, but have few or no cytoplasmic granules and lack filopodia and glycogen granules. Total hemocyte concentration in hemolymph is 328,000 ± 188,000 cells/ml.     

The inhibition of sugar transport and oxidation in fat cell ghosts by colchicine.

Colchicine inhibits glucose oxidation and the uptake of 2-deoxy-D-glucose in fat cell ghosts but has no effect on glucose oxidation by fat cell homogenates. This inhibition is rapid, reversible, and temperature-independent. Insulin-stimulated glucose oxidation and 2-deoxy-D-glucose transport are also inhibited by colchicine to an extent comparable to the basal processes.     

Chromosome-level genome assembly and characterization of Sophora Japonica

Sophora japonica is a medium-size deciduous tree belonging to Leguminosae family and famous for its high ecological, economic and medicinal value. Here, we reveal a draft genome of S. japonica, which was ∼511.49 Mb long (contig N50 size of 17.34 Mb) based on Illumina, Nanopore and Hi-C data. We reliably assembled 110 contigs into 14 chromosomes, representing 91.62% of the total genome, with an improved N50 size of 31.32 Mb based on Hi-C data. Further investigation identified 271.76 Mb (53.13%) of repetitive sequences and 31,000 protein-coding genes, of which 30,721 (99.1%) were functionally annotated. Phylogenetic analysis indicates that S. japonica separated from Arabidopsis thaliana and Glycine max ∼107.53 and 61.24 million years ago, respectively. We detected evidence of species-specific and common-legume whole-genome duplication events in S. japonica. We further found that multiple TF families (e.g. BBX and PAL) have expanded in S. japonica, which might have led to its enhanced tolerance to abiotic stress. In addition, S. japonica harbours more genes involved in the lignin and cellulose biosynthesis pathways than the other two species. Finally, population genomic analyses revealed no obvious differentiation among geographical groups and the effective population size continuously declined since 2 Ma. Our genomic data provide a powerful comparative framework to study the adaptation, evolution and active ingredients biosynthesis in S. japonica. More importantly, our high-quality S. japonica genome is important for elucidating the biosynthesis of its main bioactive components, and improving its production and/or processing.     

SARS-CoV-2 envelope protein causes acute respiratory distress syndrome (ARDS)-like pathological damages and constitutes an antiviral target

Cytokine storm and multi-organ failure are the main causes of SARS-CoV-2-related death. However, the origin of excessive damages caused by SARS-CoV-2 remains largely unknown. Here we show that the SARS-CoV-2 envelope (2-E) protein alone is able to cause acute respiratory distress syndrome (ARDS)-like damages in vitro and in vivo. 2-E proteins were found to form a type of pH-sensitive cation channels in bilayer lipid membranes. As observed in SARS-CoV-2-infected cells, heterologous expression of 2-E channels induced rapid cell death in various susceptible cell types and robust secretion of cytokines and chemokines in macrophages. Intravenous administration of purified 2-E protein into mice caused ARDS-like pathological damages in lung and spleen. A dominant negative mutation lowering 2-E channel activity attenuated cell death and SARS-CoV-2 production. Newly identified channel inhibitors exhibited potent anti-SARS-CoV-2 activity and excellent cell protective activity in vitro and these activities were positively correlated with inhibition of 2-E channel. Importantly, prophylactic and therapeutic administration of the channel inhibitor effectively reduced both the viral load and secretion of inflammation cytokines in lungs of SARS-CoV-2-infected transgenic mice expressing human angiotensin-converting enzyme 2 (hACE-2). Our study supports that 2-E is a promising drug target against SARS-CoV-2.Subject terms: Cell death, Molecular biology     

TEB/POLQ plays dual roles in protecting Arabidopsis from NO-induced DNA damage

Nitric oxide (NO) is a key player in numerous physiological processes. Excessive NO induces DNA damage, but how plants respond to this damage remains unclear. We screened and identified an Arabidopsis NO hypersensitive mutant and found it to be allelic to TEBICHI/POLQ, encoding DNA polymerase θ. The teb mutant plants were preferentially sensitive to NO- and its derivative peroxynitrite-induced DNA damage and subsequent double-strand breaks (DSBs). Inactivation of TEB caused the accumulation of spontaneous DSBs largely attributed to endogenous NO and was synergistic to DSB repair pathway mutations with respect to growth. These effects were manifested in the presence of NO-inducing agents and relieved by NO scavengers. NO induced G2/M cell cycle arrest in the teb mutant, indicative of stalled replication forks. Genetic analyses indicate that Polθ is required for translesion DNA synthesis across NO-induced lesions, but not oxidation-induced lesions. Whole-genome sequencing revealed that Polθ bypasses NO-induced base adducts in an error-free manner and generates mutations characteristic of Polθ-mediated end joining. Our experimental data collectively suggests that Polθ plays dual roles in protecting plants from NO-induced DNA damage. Since Polθ is conserved in higher eukaryotes, mammalian Polθ may also be required for balancing NO physiological signaling and genotoxicity.