Peritoneal Cavity Regulatory B Cells (B10 Cells) Modulate IFN- +CD4+ T Cell Numbers during Colitis Development in Mice

The spleen regulatory B cell subset with the functional capacity to express IL-10 (B10 cells) modulates both immune responses and autoimmune disease severity. However, the peritoneal cavity also contains relatively high frequencies of functionally-defined IL-10-competent B10 cells. In this study, peritoneal cavity B10 cells shared similar cell surface phenotypes with their spleen counterparts. However, peritoneal cavity B10 cells were 10-fold more frequent among B cells than occurred within the spleen, intestinal track or mesenteric lymph nodes and were present at higher proportions among the phenotypically-defined peritoneal B1a>B1b>B2 cell subpopulations. The development or localization of B10 cells within the peritoneal cavity was not dependent on the presence of commensal microbiota, T cells, IL-10 or B10 cell IL-10 production, or differences between their fetal liver or adult bone marrow progenitor cell origins. The BCR repertoire of peritoneal cavity B10 cells was diverse, as occurs in the spleen, and predominantly included germline-encoded VH and VL regions commonly found in either the conventional or B1 B cell compartments. Thereby, the capacity to produce IL-10 appears to be an intrinsic functional property acquired by clonally diverse B cells. Importantly, IL-10 production by peritoneal cavity B cells significantly reduced disease severity in spontaneous and induced models of colitis by regulating neutrophil infiltration, colitogenic CD4+ T cell activation and pro-inflammatory cytokine production during colitis onset. Thus, the numerically small B10 cell subset within the peritoneal cavity has regulatory function and is important for maintaining homeostasis within gastrointestinal tissues and the immune system

Metabolic Responses of Two Contrasting Lentil Genotypes to PEG-Induced Drought Stress

Among abiotic stresses, drought is undoubtedly one of the most severe environmental factors for a wide range of major crops, leading to considerable yield and economic losses. The adverse effects in crop yield reflect the result of a series of morphological and physiological changes but also changes in signaling pathways, transcriptional and post-transcriptional regulation of stress-responsive genes, and metabolic adaptations. Despite the exhausting studies elucidating plants’ metabolic response to drought, there is a knowledge gap in the biochemical mechanisms governing drought tolerance in lentil (Lens culinaris Medik.). The present study aimed to determine the fluctuations of the metabolite profiles of lentil genotypes with contrasting drought tolerance to discover possible biomarkers for screening tolerant genotypes at early growth stages. Lentil seedlings were subjected to osmotic drought stress, induced by polyethylene glycol, at two stress levels (2.5% and 5.0% PEG-6000) for a period of 20 days, while untreated plants were also included as controls. GC/ΕΙ/MS-mediated metabolic profiling was employed to monitor changes in response to osmotic drought stress. The data was subjected to OPLS-DA and OPLS-HCA for the discrimination between treatments and the discovery of trends and corresponding biomarkers. In total, the analysis yielded 150 metabolite features with highly reproducible patterns, of which the vast majority belonged to carbohydrates, carboxylic acids, and amino acids. Overall, findings highlight the differential accumulation of a series of compounds, and more importantly, the variable accumulation of certain metabolites, namely D-fructose, α,α-trehalose, myo-inositol, and L-tryptophan, in the contrasting genotypes, indicating that the adaptive metabolic responses to osmotic drought stress operate under strong genotypic dependency in lentil. Research findings provide insights into various aspects of lentil’s metabolism under drought and further offer the possibility of applying such knowledge towards effectively screening for drought-tolerant lentil germplasm at early growth stages

Metabolomic and Genomic Approach to Study Defense Induction by Nesidiocoris tenuis against Tuta absoluta and Tetranychus urticae in Tomato Plants

The phytophagy of the predator Nesidiocoris tenuis (Hemiptera: Miridae) can trigger defense responses in tomato plants against pests, such as two spotted spider mite Tetranychus urticae (Acari: Tetranychidae) and South American leaf miner Tuta absoluta (Lepidoptera: Gelechiidae). The expression of genes governing Jasmonic Acid (JA) biosynthesis pathway and fluctuations in the levels of underlying metabolites have been rarely studied in mirid-infested plants. In the present study, fifteen 3rd instar nymphs of N.tenuis were caged on each top and lower leaf of tomato plants for 4 d to induce plant defense; after this period the predators were removed. With regard to T. absoluta, oviposition preference; larval period; and pupal weight were significantly reduced in N. tenuis-punctured plants. T. urticae adults exhibited a significantly higher escape tendency and reduced survival on punctured plants. Metabolomics confirmed such observations revealing substantial differences between N. tenuis-punctured and unpunctured (control) plants. Metabolites directly associated with the activation of the JA defense pathway, such as the precursor α-linolenic acid, had increased concentrations. The expression of the defense-related genes PI-II, MYC2, VSP2, and HEL was increased in the top leaves and only VSP2 and MBP2 in the lower leaves; interestingly, in the middle (unpunctured) leaves VSP2, HEL, and MBP2 were also upregulated, indicating systemic signaling. Collectively, phytophagy of N. tenuis caused adverse effects on T. absoluta and T. urticae, whereas the multi-omics approach (phenomics, metabolomics, and genomics) offered valuable insights into the nature of the plant defense responses and provided useful evidence for future applications in integrated pest management, plausibly resulting in the reduction in the required pesticide volumes