Probiotic Pediococcus pentosaceus restored gossypol-induced intestinal barrier injury by increasing propionate content in Nile tilapia

Background Intestinal barrier is a dynamic interface between the body and the ingested food components, however, dietary components or xenobiotics could compromise intestinal integrity, causing health risks to the host. Gossypol, a toxic component in cottonseed meal(CSM), caused intestinal injury in fish or other monogastric animals. It has been demonstrated that probiotics administration benefits the intestinal barrier integrity, but the efficacy of probiotics in maintaining intestinal health when the host is exposed to gossypol remains unclear. Here, a strain(YC) affiliated to Pediococcus pentosaceus was isolated from the gut of Nile tilapia(Oreochromis niloticus) and its potential to repair gossypol-induced intestinal damage was evaluated.Results A total of 270 Nile tilapia(2.20 ± 0.02 g) were allotted in 3 groups with 3 tanks each and fed with 3 diets including CON(control diet), GOS(control diet containing 300 mg/kg gossypol) and GP(control diet containing 300 mg/kg gossypol and 10^(8) colony-forming unit(CFU)/g P. pentosaceus YC), respectively. After 10 weeks, addition of P. pentosaceus YC restored growth retardation and intestinal injury induced by gossypol in Nile tilapia. Transcriptome analysis and si RNA interference experiments demonstrated that NOD-like receptors(NLR) family caspase recruitment domain(CARD) domain containing 3(Nlrc3) inhibition might promote intestinal stem cell(ISC) proliferation, as well as maintaining gut barrier integrity. 16S r RNA sequencing and gas chromatography-mass spectrometry(GC-MS) revealed that addition of P. pentosaceus YC altered the composition of gut microbiota and increased the content of propionate in fish gut. In vitro studies on propionate's function demonstrated that it suppressed nlrc3 expression and promoted wound healing in Caco-2 cell model.Conclusions The present study reveals that P. pentosaceus YC has the capacity to ameliorate intestinal barrier injury by modulating gut microbiota composition and elevating propionate level. This finding offers a promising strategy for the feed industry to incorporate cottonseed meal into fish feed formulations.

Xylanase improves the intestinal barrier function of Nile tilapia(Oreochromis niloticus)fed with soybean(Glycine max)meal

Background Soybean(Glycine max)meal is one of the important protein sources for fish,but the non-starch polysaccharides(NSP)in soybean meal impair the intestinal barrier function.Here we aimed to investigate whether xylanase can alleviate the adverse effects on the gut barrier induced by soybean meal in Nile tilapia and to explore the possible mechanism.Results Nile tilapia(Oreochromis niloticus)(4.09±0.02 g)were fed with two diets including SM(soybean meal)and SMC(soybean meal+3,000 U/kg xylanase)for 8 weeks.We characterized the effects of xylanase on the gut barrier,and the transcriptome analysis was performed to investigate the underlying mechanism.Dietary xylanase improved intestinal morphology and decreased the concentration of lipopolysaccharide(LPS)in serum.The results of transcriptome and Western blotting showed that dietary xylanase up-regulated the expression level of mucin2(MUC2)which may be related to the inhibition of protein kinase RNA-like endoplasmic reticulum kinase(perk)/activating transcription factor 4(atf4)signaling pathways.Microbiome analysis showed that addition of xylanase in soybean meal altered the intestinal microbiota composition and increased the concentration of butyric acid in the gut.Notably,dietary sodium butyrate was supplemented into the soybean meal diet to feed Nile tilapia,and the data verified that sodium butyrate mirrored the beneficial effects of xylanase.Conclusions Collectively,supplementation of xylanase in soybean meal altered the intestinal microbiota composition and increased the content of butyric acid which can repress the perk/atf4 signaling pathway and increase the expression of muc2 to enhance the gut barrier function of Nile tilapia.The present study reveals the mechanism by which xylanase improves the intestinal barrier,and it also provides a theoretical basis for the application of xylanase in aquaculture.

Energy partitioning and evapotranspiration in a black locust plantation on the Yellow River Delta,China

Plantations of woody tree species play a crucial role in ecological security along coastal zones.Understanding energy partitioning and evapotranspiration can reveal land–atmosphere interaction processes.We investigated energy fluxes,evapotranspiration,and their related biophysical factors using eddy covariance techniques in a black locust(Robinia pseudoacacia L.)plantation in 2016,2018,and 2019 on the Yellow River Delta.Downward longwave radiation offsets 84–85%of upward longwave radiation;upward shortwave radiation accounted for 12–13%of downward shortwave radiation.The ratio of net radiation to downward radiation was 18–19%over the three years.During the growing season,latent heat flux was the largest component of net radiation;during the dormant season,the sensible heat flux was the dominant component of net radiation.The seasonal variation in daily evapotranspiration was mainly controlled by net radiation,air temperature,vapor pressure deficit,and leaf area index.Black locust phenology influenced daily evapotranspiration variations,and evapotranspiration was greater under sea winds than under land winds because soil water content at 10-cm depth was greater under sea winds during the day.Seasonal patterns of daily evaporative fraction,Bowen ratio,crop coefficient,Priestley–Taylor coefficient,surface conductance,and decoupling coefficient were mainly controlled by leaf area index.The threshold value of daily surface conductance was approximately 8 mm sover the plantation.

强旋翼尾迹涡干扰对直升机空速测量的影响

准确的空速测量对于直升机飞行安全至关重要。本文建立了基于非定常动量源理论的旋翼/机身气动干扰流场数值模拟方法,研究了旋翼尾迹涡干扰对直升机空速测量的影响。以某参考直升机为例,分析了不同旋翼拉力下,空速管布置区在全速度范围内空速值的变化特性。由于旋翼桨叶运动、机身阻滞等影响,不同位置空速管的静压相位和峰值存在差异,其中相位差异受到桨叶激励时刻影响、峰值差异受桨盘载荷与机身阻滞影响。研究也发现并解释了在特定速度段存在的由于旋翼桨尖涡通过空速管区域引起的“空速迟滞”现象。空速管的空速变化可分为下洗流主导区、迟滞区、来流主导区3个区域,对于常规构型直升机迟滞区仅在中低速度段。进一步的参数研究表明:空速管的位置越靠近机身前部、旋翼拉力越小,迟滞区的速度区间越靠前;当靠近机头时空速管并无明显的“迟滞”。最后,本文从气动干扰的角度给出了空速管的布置建议。

Effects of dietary yeast nucleotides on growth, non-specific immunity intestine growth and intestinal microbiota of juvenile hybrid tilapia Oreochromis niloticus ♀ × Oreochromis aureus ♂

This study investigated the effect of dietary supplementation of yeast nucleotides on the growth, nonspecific immunity, intestine growth and intestinal microbiota of juvenile hybrid tilapia. Tilapia(initial average weight of 8.02 g) was fed test diets supplemented with a yeast-originated nucleotide mixture(0,0.15, 0.30, 0.60, and 1.20 g/100 g diet) for 8 weeks. Fish fed the diet with 0.60% nucleotide had significantly higher weight gain than the control group(P < 0.05). Feed efficiency was improved in the fish fed 0.60 and 1.20% nucleotide compared with that in the control group. The optimal doses of nucleotides supplementation for growth and feed efficiency of fish were determined as 0.63 and 0.81%, respectively.Intestinal growth was improved in the 0.30 and 0.60% groups, as indicated by significant increase in intestine length. The fish fed 0.60 and 1.20% nucleotide showed higher super oxide dismutase(SOD)activity and lower malondialdehyde(MDA) level in the liver than the control fish, indicating enhancement of the anti-oxidant status. Serum lysozyme activity was significantly increased in the 0.15 and 0.3%nucleotide supplementation groups, suggesting an enhancement effect on the non-specific immune response. Lastly, dietary nucleotides supplementation exerted moderate influence on the intestinal microbiota of hybrid tilapia. A reduction in the cumulative abundance of putative butyrate-producing species was observed in the intestinal microbiota of fish fed diets with 0.60% nucleotide compared with the control, implying an interaction between dietary nucleotides and butyrate production. Briefly, dietary supplementation with 0.60% nucleotide improve the growth performance, immune activity and intestine growth in tilapia.

Hyperandrogenism in POMCa-deficient zebrafish enhances somatic growth without increasing adiposity

The endocrine regulatory roles of the hypothalamic-pituitary-adrenocortical axis on anxiety-like behavior and metabolic status have been found throughout animal taxa.However,the precise effects of the balancing adrenal corticosteroid biosynthesis under the influence of adrenocorticotrophic hormone(ACTH),a pro-opiomelanocortin(POMC)-derived peptide,on animal energy expenditure and somatic growth remain unknown.POMC has also been identified as one of the candidate loci for polycystic ovary syndrome,which features hyperandrogenism and some prevalence of obesity in patients.Here we show that zebrafish lacking functional POMCa exhibit similar phenotypes of stress response and body weight gain but not obesity as observed in mammalian models.In contrast with the impaired anorexigenic signaling cascade of melanocyte-stimulating hormones and leptin,which are responsible for their obesity-prone weight gain observed in various pome mutant mammals,analyses with our pomca mutant series indicate that ACTH is the key regulator for the phenotype with enhanced somatic growth without obesity in pomca-deficient zebrafish.Hypocortisolism associated with hyperandrogenism has been observed in the pomca-deficient zebrafish,with enhanced activation of mammalian target of rapamycin complex 1;reutilization of amino acids and fatty acid^-oxidation are observed in the muscle tissue of the pomca-deficient fish.After reducing hyperandrogenism by crossing our pomca mutant fish with a cy p l 7a 1-deficient background,the phenotype of enhanced somatic growth in pomca-deficient fish was no longer observed.Thus,our work also demonstrated that the role of POMCa in stress response seems to be conserved in vertebrates,whereas its effect on adipostasis is unique to teleosts.

Formation of secondary inorganic aerosol in a frigid urban atmosphere

Formation of secondary inorganic aerosol(SIA)was investigated during a six-month long heating season in Harbin,China.Enhanced sulfate formation was observed at high relative humidity(RH),with the same threshold RH(80%)for both colder and warmer measurement periods.Compared to wintertime results from Beijing,the threshold RH was considerably higher in Harbin,whereas the RH-dependent enhancement of sulfur oxidation ratio(SOR)was less significant.In addition,the high RH events were rarely encountered,and for other periods,the SOR were typically as low as~0.1.Therefore,the sulfate formation was considered inefficient in this study.After excluding the several cases with high RH,both SOR and the nitrogen oxidation ratio(NOR)exhibited increasing trends as the temperature increased,with the increase of NOR being sharper.The nitrate to sulfate ratio tended to increase with increasing temperature as well.Based on a semi-quantitative approach,this trend was attributed primarily to the temperature-dependent variations of precursors including SO_(2) and NO_(2).The influence of biomass burning emissions on SIA formation was also evident.With stronger impact of biomass burning,an enhancement in NOR was observed whereas SOR was largely unchanged.The different patterns were identified as the dominant driver of the larger nitrate to sulfate ratios measured at higher concentrations of fine particulate matter.