A soluble FcγR homolog inhibits Ig M antibody production in ayu spleen cells

Classical Fc receptors (FcRs) mediate the binding to and recognition of the Fc portion of antibodies and play an important role during immune responses in mammals. Although proteins similar to soluble FcRs have been identified in fish, little is known about the role of such proteins in fish immunity. Here, we cloned a cDNA sequence encoding a soluble Fc receptor for an immunoglobulin G (FcγR) homolog from ayu (Plecoglossus altivelis)(PaFcγRl). The predicted protein was composed of two immunoglobulin C2-like domains but lacked a transmembrane segment and a cytoplasmic tail. The PaFcγRl transcripts were distributed at low levels in all tested tissues, but significantly increased after Vibrio anguillarum infection. The PaFcγRl protein was expressed in the head kidney, trunk kidney, and neutrophils. Recombinant PaFcγRl (rPaFcγRl) was secreted when transfected into mammalian cells and the native protein was also detected in serum upon infection. rPaFcγRl was also demonstrated to bind to ayu IgM, as assessed by cell transfection. Suppressive activity of the recombinant mature protein of PaFcγRl (rPaFcγRlm) on in vitro anti-sheep red blood cell (SRBC) responses was detected by a modified hemolytic plaque forming cell assay. In conclusion, our study revealed that PaFcγRl is closely involved in the negative regulation of IgM production in the ayu spleen.

Early inoculation with caecal fermentation broth alters small intestine morphology,gene expression of tight junction proteins in the ileum,and the caecal metabolomic profiling of broilers

Background:The establishment of stable microbiota in early life is beneficial to the individual.Changes in the intestinal environment during early life play a crucial role in modulating the gut microbiota.Therefore,early intervention to change the intestinal environment can be regarded as a new regulation strategy for the growth and health of poultry.However,the effects of intestinal environmental changes on host physiology and metabolism are rarely reported.This study was conducted to investigate the effects of early inoculation with caecal fermentation broth on small intestine morphology,gene expression of tight junction proteins in the ileum,and cecum microbial metabolism of broilers.Results:Our data showed that early inoculation with caecal fermentation broth could improve intestine morphology.The small intestine villus height was significantly increased(P<0.05)in the intervened broilers compared to the control group,especially on day 28.A similar result was observed in the ratio of villus height to crypt depth(P<0.05).Meanwhile,we found early inoculation significantly increased(P<0.05)the expression levels of zonula occludens-1(ZO1)on days 14 and 28,claudin-1(CLDN1)on day 28,whereas the gene expression of claudin-2(CLDN2)was significantly decreased(P<0.05)on days 14 and 28.Gas chromatography time-of-flight/mass spectrometry(GC-TOF/MS)technology was further implemented to systematically evaluate the microbial metabolite profiles.Principal component analysis(PCA)and orthogonal partial least squares discriminant analysis(OPLS-DA)displayed a distinct trend towards separation between the fermentation broth group(F group)and the control group(C group).The differentially expressed metabolites were identified,and they were mainly functionally enriched in beta-alanine metabolism and biosynthesis of unsaturated fatty acids.In addition,1,3-diaminopropane was selected as a key biomarker that responded to early inoculation with caecal fermentation broth.Conclusions:These results provide insight into intestinal metabolomics and confirm that early inoculation with caecal fermentation broth can be used as a potential strategy to improve intestinal health of broilers.

METABOLIC AND TRANSCRIPTOME ANALYSIS REVEALS METABOLITE VARIATION AND FLAVONOID REGULATORY NETWORKS IN FRESH SHOOTS OF TEA(CAMELLIA SINENSIS)OVER THREE SEASONS

Metabolites,especially secondary metabolites,are very important in the adaption of tea plants and the quality of tea products.Here,we focus on the seasonal variation in metabolites of fresh tea shoots and their regulatory mechanism at the transcriptional level.The metabolic profiles of fresh tea shoots of 10 tea accessions collected in spring,summer,and autumn were analyzed using ultra-performance liquid chromatography coupled with quadrupole-obitrap mass spectrometry.We focused on the metabolites and key genes in the phenylpropanoid/flavonoid pathway integrated with transcriptome analysis.Multivariate statistical analysis indicates that metabolites were distinctly different with seasonal alternation.Flavonoids,amino acids,organic acids and alkaloids were the predominant metabolites.Levels of most key genes and downstream compounds in the flavonoid pathway were lowest in spring but the catechin quality index was highest in spring.The regulatory pathway was explored by constructing a metabolite correlation network and a weighted gene co-expression network.