The vicK gene of Streptococcus mutans mediates its cariogenicity via exopolysaccharides metabolism

Streptococcus mutans(S.mutans)is generally regarded as a major contributor to dental caries because of its ability to synthesize extracellular polysaccharides(EPS)that aid in the formation of plaque biofilm.The VicRKX system of S.mutans plays an important role in biofilm formation.The aim of this study was to investigate the effects of vicK gene on specific characteristics of EPS in S.mutans biofilm.We constructed single-species biofilms formed by different mutants of vicK gene.Production and distribution of EPS were detected through atomic force microscopy,scanning electron microscopy and confocal laser scanning microscopy.Microcosmic structures of EPS were analyzed by gel permeation chromatography and gas chromatography-mass spectrometry.Cariogenicity of the vicK mutant was assessed in a specific pathogen-free rat model.Transcriptional levels of cariogenicityassociated genes were confirmed by quantitative real-time polymerase chain reaction.The results showed that deletion of vicK gene suppressed biofilm formation as well as EPS production,and EPS were synthesized mostly around the cells.Molecular weight and monosaccharide components underwent evident alterations.Biofilms formed in vivo were sparse and contributed a decreased degree of caries.Moreover,expressional levels of genes related to EPS synthesis were down-regulated,except for gtfB.Our report demonstrates that vicK gene enhances biofilm formation and subsequent caries development.And this may due to its regulations on EPS metabolism,like synthesis or microcosmic features of EPS.This study suggests that vicK gene and EPS can be considered as promising targets to modulate dental caries.

Spatial variability of soil moisture in a mining subsidence area of northwest China

The current study investigated the impact of coal mining on deep soil moisture from the perspective of the absolute value of soil moisture.A combined classical statistics and multi-dimensional geo-statistics approach was employed to analyze the temporal and spatial changes in soil moisture from 0 to 10 m in the mining face of the Nalin River No.2 Mine in Northwest China from the perspective of spatial variability.The results of the study show that compared with the control area,the average value of soil moisture in 1-and 2-year subsidence areas decreased by 1.18%and 0.96%,respectively,whereas the coefcient of variation increased by 17.92%and 3.63%,respectively.Interpolation of soil moisture spatial distribution results showed that the spatial variability of soil moisture in the control area was less than that in the subsidence areas,and the spatial variability of soil moisture in the 2-year subsidence area was less than that in the 1-year subsidence area,indicating that mining increases the spatial variability of soil moisture and that the degree of spatial variability of soil moisture decreases as the subsidence enters the stable period.These results provide evidence for the mechanism by which coal mining subsidence afects soil moisture.Preferential fow caused by surface cracks,soil texture,the soil pore microstructure,and other factors in the coal mining subsidence area are the primary drivers of the increase in spatial variability of soil moisture.

Single-cell-resolution transcriptome map revealed novel genes involved in testicular germ cell progression and somatic cells specification in Chinese tongue sole with sex reversal

Female-to-male sex reversals(pseudomales)are common in lower vertebrates and have been found in natural populations,which is a concern under rapid changes in environmental conditions.Pseudomales can exhibit altered spermatogenesis.However,the regulatory mechanisms underlying pseudomale spermatogenesis remain unclear.Here,we characterized spermatogenesis in Chinese tongue sole(Cynoglossus semilaevis),a species with genetic and environmental sex determination,based on a highresolution single-cell RNA-seq atlas of cells derived from the testes of genotypic males and pseudomales.We identified five germ cell types and six somatic cell types and obtained a single-cell atlas of dynamic changes in gene expression during spermatogenesis in Chinese tongue sole,including alterations in pseudomales.We detected decreased levels of Ca^(2+)signaling pathway-related genes in spermatogonia,insufficient meiotic initiation in spermatocytes,and a malfunction of somatic niche cells in pseudomales.However,a cluster of CaSR genes and MAPK signaling factors were upregulated in undifferentiated spermatogonia of pseudomales.Additionally,we revealed that Z chromosome-specific genes,such as piwil2,dhx37,and ehmt1,were important for spermatogenesis.These results improve our understanding of reproduction after female-to-male sex-reversal and provide new insights into the adaptability of reproductive strategies in lower vertebrates.

Effects of dietary supplementation of Lactobacillus plantarum and Bacillus subtilis on growth performance,survival,immune response,antioxidant capacity and digestive enzyme activity in olive flounder(Paralichthys olivaceus)

In present study,a 10-month feeding trial was carried out to investigate effects of dietary Lactobacillus plantarum and Bacillus subtilis supplementation singly on growth performance,innate immune response,antioxidant capacity and digestive enzyme activity of olive flounder under a commercial production environment.Two experimental groups fed basal diet with supplementation of L.plantarum(5.0×107 CFU/g diet)and B.subtilis(1.0×108 CFU/g diet)respectively,and control group fed with basal diet without probiotics supplement.At harvest,serum immune parameters,liver antioxidant indices and digestive enzyme activities in liver,stomach and intestines were measured.Fish fed with B.subtilis supplemented diet showed the highest growth rate which was significantly higher than L.plantarum supplemented group(P<0.05)which was also significantly higher than control group(P<0.05).Survival rate were significantly elevated by feeding diet with L.plantarum supplementation(P<0.05),while the improvement was not significant for B.subtilis supplemented diet compared to control group.All the studied immune parameters in serum were substantially enhanced in both experimental groups.Similar results were observed for the antioxidant capacity in liver.Besides,the activities of digestive enzymes increased substantially in both experimental groups compared to control group and the detected improvement in dietary B.subtilis supplemented group were all higher than in L.plantarum supplemented group,though not all the improvements were significant.In summary,the separate supplementation of B.subtilis and L.plantarum in diet is more beneficial for growth performance and healthy status respectively.Hence,in olive flounder aquaculture,favorable effects of compounded supplementation of L.plantarum and B.subtilis are expected.

Estimationof genetic parameters for juvenile growth performance traits in oliveflounder(Paralichthys olivaceus)

The aim of this study was to evaluate genetic parameters of growth traits for improving selective breeding in olive flounder(Paralichthys olivaceus).A total of 82 full-sib families from 2 year-classes with complete pedigree information were used to estimate heritabilities and genetic/phenotypic correlations for 4 growth performance traits(body weight BW,total length TL,body height BH and condition factor K)based on uni-trait and multi-trait linear mixed models,respectively.Data were analyzed by the restricted maximum likelihood(REML)method.The heritabilities of BW,TL and BH were 0.81,0.70 and 0.61,which are relatively high,however,heritability for K is low(0.11).For all growth traits,the common full-sib effects(c^(2))were at a low to moderate level(0.14–0.20);the maternal effects(m^(2))of the traits(except K)were also detected(0.15–0.19).The phenotypic and genetic correlations among BW,TL and BH were highly positive(0.70–0.91),however,the correlations between K and the other 3 traits was low or negligible(−0.22–0.26).According to our results,these traits(except K)could be selected and enhanced simultaneously.In addition,direct selection based on TL or BH,which is an easily measurable trait,will be more favorable than selection on BW.Moreover,our results indicated that growth parameters estimated in the juvenile stage could be used as a predictor of growth performance at later growth stages.

Insights into the genetic covariation between harvest survival and growth rate in olive flounder(Paralichthys olivaceus)under commercial production environment

In aquaculture,selective breeding for survival till harvest have become an alternative strategy for improving disease resistance and production.However,knowledge of genetic parameters of harvest survival,e.g.,heritability and genetic correlations between survival and growth rate traits,is still scarce.The aims of this study were to estimate genetic parameters for harvest survival and growth rate traits under commercial farming conditions in olive flounder(Paralichthys olivaceus).Harvest survival was defined as a binary trait;growth traits were measured as average daily gain(ADG),specific growth rate(SGR),daily growth coefficient(DGC)and body weight(BW).Data from a population of 241 full-sib families(involving 39,904 individuals,four generations)were used.Heritabilities of survival were low but significant,which were 0.15±0.04 and 0.22±0.01 on observed and underlying scale,respectively.Heritability estimates for ADG,SGR and DGC were medium to high,which were 0.33±0.06,0.83±0.07,0.58±0.07,respectively.While the heritability of BW is of low magnitude(0.17±0.08).The genetic correlations between harvest survival and three growth rate traits(i.e.,ADG,SGR and DGC)were very strong(ranging from 0.66 to 0.79),which is an exciting result.However,the genetic correlation between harvest survival and BW was much lower(0.17±0.08).These results suggest that selection for harvest survival would consequentially result in concomitant increase of growth rate,and vice versa.Our findings revealed novel insights into the genetic improvement of growth rate and harvest survival through genetic selection in olive flounder.

Estimation of heritabilities of disease resistance to Edwardsiella tarda and genetic correlations between resistance and growth traits in Chinese tongue sole (Cynoglossus semilaevis)

Chinese tongue sole(Cynoglossus semilaevis)is an important marine flatfish which is widely cultured in coastal areas in China.Infectious bacterial diseases such as Edwardsiella tarda imposed serious threats to this species.A potential strategy to prevent this disease is to select resistance strains.The aim of the present work was to estimate the genetic variation of disease resistance to E.tarda and to evaluate the genetic correlations between resistance traits and growth traits.Three types of models were fitted by using different trait definitions(binary,continuous and categorical).After a 9-day challenge test,the overall survival was 75.4%(ranging from 6.4%to 100%in families),and at test day 6,the overall survival was 50.7%.We set test day 6 and 9 as cut-off point times respectively.The heritabilities of survival traits were ranging from 0.10 to 0.36.Considerably higher heritability values were obtained at day 6 than at day 9,regardless of which model or trait definition used(except Trait 2 in LIN).The genetic correlations between disease resistance traits and growth traits(i.e.body weight and total length)were low and not significant from zero(−0.12–0.24).There is a substantial re-ranking of families when defined resistance as categorical and continuous traits compared to binary trait.These results confirm the existence of genetic variation for resistance against E.tarda and weak genetic correlations indicate that joint genetic improvement of E.tarda resistance and growth is scarcely available.

Efficient scarless skin regeneration enabled by loading micronized amnion in a bioinspired adhesive wound dressing

Complete skin reconstruction is a hierarchical,physiological assembly process involving healing of the epidermis,dermis,vasculature,nerves,and cutaneous appendages.To date,few works have reported complete skin regeneration,particularly lacking vascular structures and hair follicles after full skin defects.In this study,a hydrogel derived from the skin secretion of Andrias davidianus(SSAD)that features adhesiveness was used as a bioactive scaffold to load micronized amnion(MA).The SSAD hydrogel was found to promote the migration and proliferation of amnion stem cells and human keratinocytes,as well as inhibit their apoptosis in vitro.In a rat full-skin defect model,the regeneration of skin appendages was observed at the wound area,achieving scarless healing.Transcriptome analyses further validated that SSAD could positively regulate cell migration,proliferation,and differentiation.These functions might be attributed to the abundant growth factors present in the SSAD.Synergized by the delivery of MA,SSAD loaded with the MA could achieve a significantly better skin regeneration effect than SSAD or MA used alone,providing a simple yet highly effective means to obtain complete,scarless skin regeneration,suggesting favorable potential for clinical translation.