Nodal coordinates the anterior-posterior patterning of germ layers and induces head formation in zebrafish explants.

Much progress has been made toward generating analogs of early embryos, such as gastruloids and embryoids, in vitro. However, methods for how to fully mimic the cell movements of gastrulation and coordinate germ-layer patterning to induce head formation are still lacking. Here, we show that a regional Nodal gradient applied to zebrafish animal pole explant can generate a structure that recapitulates the key cell movements of gastrulation. Using single-cell transcriptome and in situ hybridization analysis, we assess the dynamics of the cell fates and patterning of this structure. The mesendoderm differentiates into the anterior endoderm, prechordal plate, notochord, and tailbud-like cells along an anterior-posterior axis, and an anterior-posterior-patterned head-like structure (HLS) progressively forms during late gastrulation. Among 105 immediate Nodal targets, 14 genes contain axis-induction ability, and 5 of them induce a complete or partial head structure when overexpressed in the ventral side of zebrafish embryos.

Reduced-Cost Production of Sophorolipids by Starmerella bombicola CGMCC1576 Grown on Cottonseed Molasses and Cottonseed Oil-Based Medium.

A large-scale application of sophorolipids (SLs) was blocked by their high production cost. One feasible way to reduce the cost of SL production is to develop cheap feedstocks as the substrates for SL fermentation. In the present work, cottonseed molasses (CM), a waste from raffinose production, was used as the hydrophilic substrate;, and cottonseed oil (CO) was used as a hydrophobic substrate for SL production by Starmerella bombicola CGMCC 1576. The primary optimization of carbon sources, nitrogen source and inorganic salts, produced 57.6 ± 2.3 g/L of total SLs and 24.0 ± 1.2 g/L of lactonic SLs on CM and CO, almost equal to the titer of SLs produced from glucose and oleic. A response surface method was applied to optimize the fermentation medium for growth and SL production of S. bombicola. The production of total SLs reached 58.4 ± 3.4 g/L, and lactonic SLs were elevated to more than 25.0 ± 1.9 g/L. HPLC-MS analysis showed that the compositions of SLs produced by S. bombicola on CM and CO were very similar to those on glucose and oleic acid. These results suggested that cottonseed molasses and cottonseed oil can be used as renewable cheap substrates for the reduced-cost production of SLs.

Mycn regulates intestinal development through ribosomal biogenesis in a zebrafish model of Feingold syndrome 1.

Feingold syndrome type 1, caused by loss-of-function of MYCN, is characterized by varied phenotypes including esophageal and duodenal atresia. However, no adequate model exists for studying the syndrome's pathological or molecular mechanisms, nor is there a treatment strategy. Here, we developed a zebrafish Feingold syndrome type 1 model with nonfunctional mycn, which had severe intestinal atresia. Single-cell RNA-seq identified a subcluster of intestinal cells that were highly sensitive to Mycn, and impaired cell proliferation decreased the overall number of intestinal cells in the mycn mutant fish. Bulk RNA-seq and metabolomic analysis showed that expression of ribosomal genes was down-regulated and that amino acid metabolism was abnormal. Northern blot and ribosomal profiling analysis showed abnormal rRNA processing and decreases in free 40S, 60S, and 80S ribosome particles, which led to impaired translation in the mutant. Besides, both Ribo-seq and western blot analysis showed that mTOR pathway was impaired in mycn mutant, and blocking mTOR pathway by rapamycin treatment can mimic the intestinal defect, and both L-leucine and Rheb, which can elevate translation via activating TOR pathway, could rescue the intestinal phenotype of mycn mutant. In summary, by this zebrafish Feingold syndrome type 1 model, we found that disturbance of ribosomal biogenesis and blockage of protein synthesis during development are primary causes of the intestinal defect in Feingold syndrome type 1. Importantly, our work suggests that leucine supplementation may be a feasible and easy treatment option for this disease.

A Cumulative Effect by Multiple-Gene Knockout Strategy Leads to a Significant Increase in the Production of Sophorolipids in Starmerella Bombicola CGMCC 1576.

Sophorolipids (SLs), an important biosurfactant produced by S. bombicola, were one of the most potential substitutes for chemical surfactants. Few reports on the transcriptional regulation of SLs synthesis and the engineered strains with high-yield SLs were available. In this study, a Rim9-like protein (Rlp) and three transcription factors (ztf1, leu3, gcl) were mined and analyzed, and a progressive enhancement of SLs production was achieved through cumulative knockouts of three genes. The sophorolipid production of ΔrlpΔleu3Δztf1 reached 97.44 g/L, increased by 50.51% than that of the wild-type strain. Compared with the wild-type strain, the flow of glucose to SLs synthesis pathways was increased, and the synthesis of branched-chain amino acids was reduced in ΔrlpΔleu3Δztf1. The amount of UDP-glucose, the substrate for two glycosyltransferases, also increased, and the expression level of the key genes sble and UGPase for SLs synthesis increased by 2.2 times, respectively. The multiple-gene knockout strategy was proved to be highly effective to construct the engineered strain with high-yield SLs production, and this strain was a superior strain for industrial fermentation of SLs and reduced SLs production costs.

Identification of Four Secreted Aspartic Protease-Like Proteins Associated With Sophorolipids Synthesis in Starmerella bombicola CGMCC 1576.

The non-pathogenic yeast Starmerella bombicola CGMCC 1576 is an efficient producer of sophorolipids (SLs). The lactonic SLs are mainly produced with yeast extract, and the acidic SLs are mainly produced with ammonium sulfate. Naturally produced SLs are a mixture of various lactonic and acidic SLs. Usually, the SL mixture is not well separated technically, and the separation cost is relatively high. In order to reduce the cost of separation, four secreted aspartic protease-like proteins were identified through proteomic analysis of fermentation broth of S. bombicola under different nitrogen source conditions. The coding genes of the four proteins, namely, sapl1, sapl2, sapl3, and sapl4, are of high sequence similarity (above 55%) and included in a gene cluster. The expression of the four genes was significantly upregulated on (NH4)2SO4 compared with that on yeast extract. The four genes were deleted together to generate a strain Δsapl. The titer of SLs in Δsapl reached 60.71 g/L after 5 days of fermentation using (NH4)2SO4 as the nitrogen source and increased by 90% compared with the wild-type strain. The concentration of acidic SLs was 55.84 g/L, accounting for 92% of the total SLs. The yield of SLs from glucose (g/g) by Δsapl was 0.78, much higher than that by wild-type strain (0.47). However, no increase of SLs production was observed in Δsapl under yeast extract condition. Compared with that of the wild-type strain, the expression levels of the key genes for SLs synthesis were all upregulated to varying degrees in Δsapl under (NH4)2SO4 conditions, and particularly, the expression level of ugta1 encoding UDP glucosyltransferase was upregulated by 14.3-fold. The results suggest that the sapl gene cluster is negatively involved in the production of SLs in the case of (NH4)2SO4 by restraining the expression of the key genes involved in SLs synthesis. The Δsapl strain is an excellent producer of high-titer and high-yield acidic SLs.

HEV prevalence and potential risk factors in a large multi-ethnic youth cohort in China.

BACKGROUND: This cohort study was designed to investigate the prevalence of and potential risk factors of HEV infection in a large multi-ethnic youth cohort in China. METHODS: Blood samples were collected from participants (n = 6269) and serum was isolated. All serum samples were tested for anti-HEV IgG, anti-HEV IgM antibodies using commercial enzyme immunoassay kits (Wantai Biological Pharmacy Enterprise, Beijing, China). RESULTS: The overall rate of anti-HEV IgG and anti-HEV IgM prevalence was 4.78% and 0.14%, 0.03% were positive for both anti-HEV IgG and anti-HEV IgM antibodies. Anti-HEV IgG positivity is significantly higher in females (5.27%) compared to males (4.14%) (P = 0.028). Anti-HEV IgG prevalence is significantly (P = 0.0001) higher in Dong (17.57%), Miao (12.23%), Yi (11.04%), Gelao (9.76%), and Bai (10.00%) compared to other ethnic groups. It is significantly higher in Guizhou (11.4%), Sichuan (10.1%), Yunnan (9.3%), and Guangxi (6.9%) than that other province. We found that ethnicity and provincial background are significantly associated with HEV infection in this cohort. CONCLUSION: This study provides comprehensive information on HEV prevalence in multi-ethnic populations in China. However, our study only focused on a youth population from different provinces of China. Future studies are recommended to investigate HEV prevalence in other age groups of the ethnic populations.

Sophorolipid Production Using Lignocellulosic Biomass by Co-culture of Several Recombinant Strains of Starmerella bombicola with Different Heterologous Cellulase Genes from Penicillum oxalicum.

One of the reasons hindering large-scale application of sophorolipids (SLs) is high production cost. In this study, six recombinant strains of Starmerella bombicola, sbEG1, sbEG2, sbCBH1, sbCBH1-2, sbBGL1, and sbCBH2 expressing cellulase genes eg1, eg2, cbh, cbh1-2, bgl1, and cbh2 from Penicillium oxalicum were respectively constructed. Four strains showed cellulase activities and were co-cultivated in fermentation media containing 2% glucose, 1% Regenerated Amorphous Cellulose (RAC), 2% glucose, and 1% RAC, respectively. After 7 days' cultivation, concentration of SLs in medium with 1% RAC (g/L) reached 1.879 g/L. When 2% glucose and 1% of RAC were both contained, the titer of SLs increased by 39.5% than that of control strain and increased by 68.8% than that in the medium with only 2% glucose. Results demonstrated that cellulase genes from filamentous fungi in S. bombicola can function to degrade lignocellulosic cellulose to produce SLs.

Identification and characterization of a protein Bro1 essential for sophorolipids synthesis in Starmerella bombicola.

Sophorolipids (SLs) are surface-active molecules produced by the non-pathogenic yeast Starmerella bombicola CGMCC 1576. Several genes involved in the synthesis of SLs have been identified. However, the regulation mechanism of the synthesis pathway for SLs has not been investigated. We recently discovered a protein in S. bombicola, which is structurally related to Yarrowia lipolytica YlBro1. To identify the function of the protein SbBro1 in S. bombicola, the deletion, overexpression, and complementary mutant strains were constructed. We found that the deletion mutant no longer produced SLs. Transcriptome analysis indicated that the expression levels of the key enzyme genes of SLs biosynthetic pathway were significantly down-regulated in the Δbro1, especially the expression level of cyp52m1 encoding the first rate-limiting enzyme in SL synthesis pathway was down-regulated 13-folds and the expression of fatty acid ß-oxidation-related enzymes was also down-regulated. This study can give insight into the regulation of SL synthesis.

Identifying water sources used by alpine riparian plants in a restoration zone on the Qinghai-Tibet Plateau: Evidence from stable isotopes.

Riparian zones are vulnerable to water regimes, which alter soil water availability and impact the persistence of riparian plants. However, little is known about the water use patterns of alpine riparian shrubs (e.g., Myricaria squamosa) in response to changes in soil water availability on the Qinghai-Tibet Plateau. This study examined the water-use patterns of M. squamosa along a zone of gradual degradation (light, moderate, and severe), located in the lower reaches of the Shaliu River in the Qinghai Lake watershed. Stable water isotopes (δ2H and δ18O) in xylem water, soil water and groundwater, as well as leaf water potential were monitored during the growing seasons from 2012 to 2013, and quantified the water-use proportions via MixSIAR model. Results showed significant differences in the isotopic signatures of M. squamosa from the light, moderate, and severe degradation sites across seasons, suggesting that M. squamosa exploited different water sources. MixSIAR results also revealed that M. squamosa used high proportions of shallow soil water in the light degradation site (35.4%) compared with the severe degradation sites (13.4%). By contrast, M. squamosa exhibited an ability to shift its water sources and to rely more on groundwater in the severe degradation site across seasons. The contrasting water-use patterns of M. squamosa along the gradual degradation zone were closely linked with the distributions of active root zones when competing for water. Higher predawn leaf water potential (Ψpd) of M. squamosa (mean Ψpd = -2.29 ±â€¯0.7 MPa) was found in the light degradation site and lower Ψpd values in the severe degradation site (mean Ψpd = -3.3 ±â€¯0.8 MPa), suggesting that M. squamosa depended on a high degree of flexible plasticity in water use to alleviate water stress along the gradual degradation. These results linked to water-use patterns and ecophysiological characteristics (e.g., Ψpd) of plants responding to changes in available water are important for informing decision-making management strategies designed to prevent ecological degradation.

Increased ratio of high sensitivity C-reactive protein to interleukin-10 as a potential peripheral biomarker of schizophrenia and aggression.

BACKGROUND: Many studies have indicated that immune dysfunction might be involved in the physiopathology of schizophrenia and aggression. This study aimed to investigate the correlation between high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-10 and clinical characteristics, especially aggression, and to explore the potential role of hsCRP and IL-10 as plasma biomarkers of schizophrenia. METHODS: Forty-one patients with schizophrenia and forty healthy individuals were enrolled. Psychopathological severity and aggression were assessed using the Positive and Negative Syndrome Scale (PANSS) and Modified Overt Aggression Scale (MOAS). Plasma concentrations of hsCRP and IL-10 were assessed by enzyme-linked immunosorbent assay (ELISA). RESULTS: (1) Higher levels of hsCRP (p<0.001), lower levels of logIL-10 (p<0.001) and higher ratio of hsCRP to IL-10 (p<0.001) were observed in the plasma of patients with schizophrenia, compared to healthy controls; (2) ROC (receiver operating characteristic) curve analysis revealed that ratio of hsCRP/IL-10 (predictive value: 0.783, p<0.01; sensitivity: 85.4%; specificity: 67.5%) was more applicable as a biomarker to distinguish patients with schizophrenia from the control group than hsCRP and IL-10 alone (predictive value: 0.718, p<0.01; 0.275, p<0.001, respectively); (3) we found positive correlations between hsCRP and the total score and verbal aggression score of MOAS (r=0.654, p<0.01; r=0.678, p<0.05), and between hsCRP/IL-10 and the total score of MOAS (r=0.636, p<0.01). CONCLUSIONS: Our results suggest the possible function of hsCRP and IL-10 in the pathogenesis of schizophrenia and the possible value of hsCRP/IL-10 as a potential peripheral biomarker of schizophrenia. This finding also suggests a relationship between hsCRP, IL-10 and their ratio with aggression in patients with schizophrenia.

Higher Plasma S100B Concentrations in Schizophrenia Patients, and Dependently Associated with Inflammatory Markers.

Glial damage and immune dysfunction are involved in pathogenesis of schizophrenia. However, interaction between glial damage and immune dysfunction in schizophrenia is undefined. This study aims to compare plasma S100 calcium binding protein (S100B) levels between schizophrenia patients and healthy participants, and to determine if immune markers are independently related with concentration of S100B in schizophrenia patients. Forty-one schizophrenia patients and thirty-three healthy volunteers were enrolled. Enzyme-linked immunosorbent assay (ELISA) was used to assess the concentrations of plasma S100B and inflammatory markers. We found that concentrations of S100B were elevated in schizophrenia patients than healthy participants (p < 0.05), and were negatively related with the severity of symptoms (p = 0.046). Receiver operating characteristic (ROC) curve analysis showed that different S100B levels between schizophrenia and healthy participants can be used as a clinical diagnostic factor (predictive value: 0.666, p = 0.015). Multiple linear regression analysis found that length of illness (Beta = -0.161), plasma levels of inflammatory regulation factors (including TGF-ß1, logIL-23 and logIL-10) (Beta = 0.119, 0.475, 0.514) were independently associated with concentrations of S100B (Adjusted R(2) = 0.897, p < 0.001). Therefore, our results suggest the possible function of S100B in pathogenesis of schizophrenia, and implicate the important role of autoimmune response and balance to glial dysfunction in patients with schizophrenia.

[Impacts of Ochotona pallasi disturbance on alpine grassland community characteristics].

Plateau pika is the main fossorial mammal in the alpine grassland in Qinghai Lake Watershed of Northwest China. Based on the field investigation data from 18 alpine grassland quadrats in the Watershed, and by using redundancy analysis (RDA) and the surface fitting offered by 'R-Vegan' , the disturbance intensity of plateau pika (Ochotona pallasi) was classified as four levels. In order to explore the impacts of plateau pika disturbance on the alpine grassland ecosystem and its grazing quality, the community characteristics under different disturbance intensities by plateau pika were analyzed, and a conceptual model about the alpine grassland community succession was proposed. The results showed that with the increase of the disturbance intensity, the dominant species changed from Juncus roemerianus to Poa pratensis and Laux maritima. When the disturbance was small, the community had high quantitative values of coverage, aboveground biomass, biodiversity, and species richness, but the proportion of weeds was also high. When the disturbance was large, the quantitative values were the lowest, while the proportion of weeds was the highest. When the disturbance was moderate, the community had relatively high quantitative values, and the proportion of grasses and sedges was the highest. It was concluded that the community' s characteristic values under low plateau pika disturbance intensity were high but the grazing quality was low, while high disturbance intensity resulted in the grassland degradation. Therefore, the disturbance intensity in the threshold could maintain the stability of alpine grassland ecosystem and improve its grazing quality.