Widespread prevalence but contrasting patterns of intragenomic rRNA polymorphisms in nematodes: Implications for phylogeny,species delimitation and life history inference

Ribosomal RNA genes have long been a favoured locus in phylogenetic and metabarcoding studies. Within a genome, rRNA loci are organized as tandem repeated arrays and the copies are homogenized through the process of concerted evolution. However, some level of rRNA variation (intragenomic polymorphism) is known to persist and be maintained in the genomes of many species. In nematode worms, the extent of rRNA polymorphism (RP) across species and the evolutionary and life history factors that contribute to the maintenance of intragenomic RP is largely unknown. Here, we present an extensive analysis across 30 terrestrial nematode species representing a range of free‐living and parasitic taxa isolated worldwide. Our results indicate that RP is common and widespread, ribosome function appears to be maintained despite mutational changes, and intragenomic variants are stable in the genome and neutrally evolving. However, levels of variation were varied widely across rRNA locus and species, with some taxa observed to lack RP entirely. Higher levels of RP were significantly correlated with shorter generation time and high reproductive rates, and population‐level factors may play a role in the geographic and phylogenetic structuring of rRNA variants observed in genera such as Rotylenchulus and Pratylenchus. Although RP did not dramatically impact the clustering and recovery of taxa in mock metabarcoding analyses, the present study has significant implications for global biodiversity estimates of nematode species derived from environmental rRNA amplicon studies, as well as our understanding of the evolutionary and ecological factors shaping genetic diversity across the nematode Tree of Life.     

Interaction between mesenchymal stromal cell-derived extracellular vesicles and immune cells by distinct protein content

Mesenchymal stromal cells (MSCs) can effectively contribute to tissue regeneration inside the inflammatory microenvironment mostly through modulating immune responses. MSC-derived extracellular vesicles (MSC-EVs) display immunoregulatory functions similar to parent cells. Interactions between MSC-EVs and immune cells make them an ideal therapeutic candidate for infectious, inflammatory, and autoimmune diseases. These properties of MSC-EVs have encouraged researchers to perform extensive studies on multiple factors that mediate MSC-EVs immunomodulatory effects. Investigation of proteins involved in the complex interplay of MSC-EVs and immune cells may help us to better understand their functions. Here, we performed a comprehensive proteomic analysis of MSC-EVs that was previously reported by ExoCarta database. A total of 938 proteins were identified as MSC-EV proteome using quantitative proteomics techniques. Kyoto Encyclopedia of Genes and Genomes analysis demonstrates that ECM–receptor interaction, focal adhesion, and disease-specific pathways are enriched in MSC-EVs. By detail analysis of proteins presence in immune system process, we found that expression of some cytokines, chemokines, and chemokine receptors such as IL10, HGF, LIF, CCL2, VEGFC, and CCL20, which leads to migration of MSC-EVs to injured sites, suppression of inflammation and promotion of regeneration in inflammatory and autoimmune diseases. Also, some chemoattractant proteins such as CXCL2, CXCL8, CXCL16, DEFA1, HERC5, and IFITM2 were found in MSC-EV proteome. They may actively recruit immune cells to the proximity of MSC or MSC-EVs, may result in boosting immune response under specific circumstances, and may have protective role in infectious diseases. In this review, we summarize available information about immunomodulation of MSC-EVs with particular emphasis on their proteomics analysis.     

Partial characterization of an exopolysaccharide secreted by a marine bacterium,Vibrio neocaledonicus sp. nov., from New Caledonia

Aims

Exopolysaccharides (EPS) are industrially valuable molecules with numerous useful properties. This study describes the techniques used for the identification of a novel Vibrio bacterium and preliminary characterization of its EPS.

Methods and Results

Bioprospection in marine intertidal areas of New Caledonia followed by screening for EPS producing brought to selection of the isolate NC470. Phylogenetic analysis (biochemical tests, gene sequencing and DNA–DNA relatedness) permitted to identify NC470 as a new member of the Vibrio genus. The EPS was produced in batch fermentation, purified using the ultrafiltration process and analysed by colorimetry, Fourier Transform Infrared spectroscopy, gas chromatography, Nuclear Magnetic Resonance and HPLC‐size exclusion chromatography. This EPS exhibits a high N‐acetyl‐hexosamines and uronic acid content with a low amount of neutral sugar. The molecular mass was 672 × 10³ Da. These data are relevant for possible technological exploitation.

Conclusions

We propose the name Vibrio neocaledonicus sp. nov for this isolate NC470, producing an EPS with an unusual sugar composition. Comparison with other known polymers permitted to select applications for this polymer.

Significance and Impact of the Study

This study contributes to evaluate the marine biodiversity of New Caledonia. It also highlights the biotechnological potential of New Caledonia marine bacteria.     

Possible molecular mechanisms of glucose-lowering activities of Momordica charantia (karela) in diabetes

Diabetes mellitus is a highly prevalent metabolic disorder which is characterized by impaired glucose tolerance, with a relative or absolute insulin deficiency and profound changes in the metabolism of macronutrients. Traditional and complementary medicine is therapeutic strategies that have both been applied to improving glycemic control. Momordica charantia is one of the plant-based, folk medicines that used for improving glycemic control. We aimed to review, the effects of M. charantia on blood glucose with a clarification of the molecular pathways involved. Of the compounds derived from the plants, the insulin-like peptide, charantin, and the alkaloid vicine, have been reported to have hypoglycemic effects. Different mechanisms contribute to the antidiabetic activities of M. charantia, these include increasing pancreatic insulin secretion, decreasing insulin resistance and increasing peripheral and skeletal muscle cell glucose utilization, inhibition of intestinal glucose absorption and suppressing of key enzymes in the gluconeogenic pathways.     

Olfactory Sensitivity for Six Predator Odorants in CD-1 Mice,Human Subjects,and Spider Monkeys

Using a conditioning paradigm, we assessed the olfactory sensitivity of six CD-1 mice (Mus musculus) for six sulfur-containing odorants known to be components of the odors of natural predators of the mouse. With all six odorants, the mice discriminated concentrations <0.1 ppm (parts per million) from the solvent, and with five of the six odorants the best-scoring animals were even able to detect concentrations <1 ppt (parts per trillion). Four female spider monkeys (Ateles geoffroyi) and twelve human subjects (Homo sapiens) tested in parallel were found to detect the same six odorants at concentrations <0.01 ppm, and with four of the six odorants the best-scoring animals and subjects even detected concentrations <10 ppt. With all three species, the threshold values obtained here are generally lower than (or in the lower range of) those reported for other chemical classes tested previously, suggesting that sulfur-containing odorants may play a special role in olfaction. Across-species comparisons showed that the mice were significantly more sensitive than the human subjects and the spider monkeys with four of the six predator odorants. However, the human subjects were significantly more sensitive than the mice with the remaining two odorants. Human subjects and spider monkeys significantly differed in their sensitivity with only two of the six odorants. These comparisons lend further support to the notion that the number of functional olfactory receptor genes or the relative or absolute size of the olfactory bulbs are poor predictors of a species’ olfactory sensitivity. Analysis of odor structure–activity relationships showed that in both mice and human subjects the type of alkyl rest attached to a thietane and the type of oxygen moiety attached to a thiol significantly affected olfactory sensitivity.     

Action mechanisms of n-3 polyunsaturated fatty acids on the oocyte maturation and developmental competence: Potential advantages and disadvantages

Infertility is a growing problem worldwide. Currently, in vitro fertilization (IVF) is widely performed to treat infertility. However, a high percentage of IVF cycles fails, due to the poor developmental potential of the retrieved oocyte to generate viable embryos. Fatty acid content of the follicular microenvironment can affect oocyte maturation and the subsequent developmental competence. Saturated and monounsaturated fatty acids are mainly used by follicle components as primary energy sources whereas polyunsaturated fatty acids (PUFAs) play a wide range of roles. A large body of evidence supports the beneficial effects of n-3 PUFAs in prevention, treatment, and amelioration of some pathophysiological conditions including heart diseases, cancer, diabetes, and psychological disorders. Nevertheless, current findings regarding the effects of n-3 PUFAs on reproductive outcomes in general and on oocyte quality more specifically are inconsistent. This review attempts to provide a comprehensive overview of potential molecular mechanisms by which n-3 PUFAs affect oocyte maturation and developmental competence, particularly in the setting of IVF and thereby aims to elucidate the reasons behind current discrepancies around this topic.