黑眉锦蛇消化道6种酶的组织化学定位

目的研究黑眉锦蛇消化道酸性磷酸酶(ACP)、碱性磷酸酶(ALP)、过氧化物酶(POX)、非特异性酯酶(NSE)、腺苷三磷酸酶(ATPase)、琥珀酸脱氢酶(SDH)等酶的分布。方法消化道分8个部位取材,应用冰冻切片、石蜡切片、酶组织化学技术及光密度定量分析。结果 ACP主要分布于十二指肠至回肠的黏膜上皮,十二指肠和空肠酶活性显著较高(P<0.05);ALP分布于食管、十二指肠至回肠的黏膜上皮,十二指肠酶活性最高(P<0.05);POX和NSE在整个消化道黏膜上皮和黏膜固有层中均有分布,胃幽门和直肠酶活性较低(P<0.05);ATPase在消化道除直肠未检测到酶活性外,其它部位均有分布,以十二指肠酶活性最高(P<0.05);SDH除食管未检测到酶活性外,其它部位均有分布,胃中胃腺部酶活性较高(P<0.05)。结论黑眉锦蛇消化道黏膜酶的分布同其它动物有相似之处,也有其自身特点。不同酶的分布和消化道各部位的生理机能密切相关。     

Chromosome-level wild Hevea brasiliensis genome provides new tools for genomic-assisted breeding and valuable loci to elevate rubber yield

The rubber tree (Hevea brasiliensis) is grown in tropical regions and is the major source of natural rubber. Using traditional breeding approaches, the latex yield has increased by sixfold in the last century. However, the underlying genetic basis of rubber yield improvement is largely unknown. Here, we present a high-quality, chromosome-level genome sequence of the wild rubber tree, the first report on selection signatures and a genome-wide association study (GWAS) of its yield traits. Population genomic analysis revealed a moderate population divergence between the Wickham clones and wild accessions. Interestingly, it is suggestive that H. brasiliensis and six relatives of the Hevea genus might belong to the same species. The selective sweep analysis found 361 obvious signatures in the domesticated clones associated with 245 genes. In a 15-year field trial, GWAS identified 155 marker–trait associations with latex yield, in which 326 candidate genes were found. Notably, six genes related to sugar transport and metabolism, and four genes related to ethylene biosynthesis and signalling are associated with latex yield. The homozygote frequencies of the causal nonsynonymous SNPs have been greatly increased under selection, which may have contributed to the fast latex yield improvement during the short domestication history. Our study provides insights into the genetic basis of the latex yield trait and has implications for genomic-assisted breeding by offering valuable resources in this new domesticated crop.     

Molecular Epidemiology and Clinical Characteristics of Drug-Resistant Mycobacterium tuberculosis in a Tuberculosis Referral Hospital in China

Background

Despite the large number of drug-resistant tuberculosis (TB) cases in China, few studies have comprehensively analyzed the drug resistance-associated gene mutations and genotypes in relation to the clinical characteristics of M. tuberculosis (Mtb) isolates.

Methodology/Principal Findings

We thus analyzed the phenotypic and genotypic drug resistance profiles of 115 Mtb clinical isolates recovered from a tuberculosis referral hospital in Beijing, China. We also performed genotyping by 28 loci MIRU-VNTR analysis. Socio-demographic and clinical data were retrieved from medical records and analyzed. In total, 78 types of mutations (including 42 previously reported and 36 newly identified ones) were identified in 115 Mtb clinical isolates. There was significant correlation between phenotypic and genotypic drug resistance rates for first-line anti-TB drugs (P<0.001). Genotyping revealed 101 MIRU-VNTR types, with 20 isolates (17.4%) being clustered and 95 isolates (82.6%) having unique genotypes. Higher proportion of re-treatment cases was observed among patients with clustered isolates than those with unique MIRU-VNTR genotypes (75.0% vs. 41.1%). Moreover, clinical epidemiological links were identified among patients infected by Mtb strains belonging to the same clusters, suggesting a potential of transmission among patients.

Conclusions/Significance

Our study provided information on novel potential drug resistance-associated mutations in Mtb. In addition, the genotyping data from our study suggested that enforcement of the implementation of genotyping in diagnostic routines would provide important information for better monitor and control of TB transmission.     

Lin28a Protects against Hypoxia/Reoxygenation Induced Cardiomyocytes Apoptosis by Alleviating Mitochondrial Dysfunction under High Glucose/High Fat Conditions

Aim

The aim of the present study was to investigate the role of Lin28a in protecting against hypoxia/reoxygenation (H/R)-induced cardiomyocytes apoptosis under high glucose/high fat (HG/HF) conditions.

Methods

Primary cardiomyocytes which were isolated from neonatal mouse were randomized to be treated with lentivirus carrying Lin28a siRNA, Lin28acDNA 72 h before H/R (9 h/2 h). Cardiomyocytes biomarkers release (LDH and CK), cardiomyocytes apoptosis, mitochondria biogenesis and morphology, intracellular reactive oxygen species (ROS) production, ATP content and inflammatory cytokines levels after H/R injury in high glucose/high fat conditions were compared between groups. The target proteins of Lin28a were examined by western blot analysis.

Results

Our results revealed that Lin28a cDNA transfection (overexpression) significantly inhibited cardiomyocyte apoptotic index, improved mitochondria biogenesis, increased ATP production and reduced ROS production as compared with the H/R group in HG/HF conditions. Lin28a siRNA transfection (knockdown) rendered the cardiomyocytes more susceptible to H/R injury as evidenced by increased apoptotic index, impaired mitochondrial biogenesis, decreased ATP production and increased ROS level. Interestingly, these effects of Lin28a were blocked by pretreatment with the PI3K inhibitor wortmannin. Lin28a overexpression increased, while Lin28a knockdown inhibited IGF1R, Nrf-1, Tfam, p-IRS-1, p-Akt, p-mTOR, p-p70s6k, p-AMPK expression levels after H/R injury in HG/HF conditions. Moreover, pretreatment with wortmannin abolished the effects of Lin28a on the expression levels of p-AKT, p-mTOR, p-p70s6k, p-AMPK.

Conclusions

The present results suggest that Lin28a inhibits cardiomyocytes apoptosis by enhancing mitochondrial biogenesis and function under high glucose/high fat conditions. The mechanism responsible for the effects of Lin28a is associated with the PI3K/Akt dependent pathway.     

Pesticide Exposure as a Risk Factor for Myelodysplastic Syndromes: A Meta-Analysis Based on 1,942 Cases and 5,359 Controls

Objective

Pesticide exposure has been linked to increased risk of cancer at several sites, but its association with risk of myelodysplastic syndromes (MDS) is still unclear. A meta-analysis of studies published through April, 2014 was performed to investigate the association of pesticide exposure with the risk of MDS.

Methods

Studies were identified by searching the Web of Science, Cochrane Library and PubMed databases. Summary odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were calculated using random- or fixed-effect models.

Results

This meta-analysis included 11 case-control studies, all of which demonstrated a correlation between pesticide exposure and a statistically significant increased risk of MDS (OR = 1.95, 95% CI 1.23–3.09). In subgroup analyses, patients with pesticide exposure had increased risk of developing MDS if they were living in the Europe or Asia and had refractory anemia (RA) or RA with ringed sideroblasts (RARS). Moreover, in the analysis by specific pesticides, increased risk was associated with exposure to insecticides (OR = 1.71, 95% CI 1.22–2.40) but not exposure to herbicides or fungicides.

Conclusion

This meta-analysis supports the hypothesis that exposure to pesticides increases the risk of developing MDS. Further prospective cohort studies are warranted to verify the association and guide clinical practice in MDS prevention.     

Endothelial FAK is essential for vascular network stability, cell survival, and lamellipodial formation

Morphogenesis of a vascular network requires dynamic vessel growth and regression. To investigate the cellular mechanism underlying this process, we deleted focal adhesion kinase (FAK), a key signaling mediator, in endothelial cells (ECs) using Tie2-Cre mice. Targeted FAK depletion occurred efficiently early in development, where mutants exhibited a distinctive and irregular vasculature, resulting in hemorrhage and lethality between embryonic day (e) 10.5 and 11.5. Capillaries and intercapillary spaces in yolk sacs were dilated before any other detectable abnormalities at e9.5, and explants demonstrate that the defects resulted from the loss of FAK and not from organ failure. Time-lapse microscopy monitoring EC behavior during vascular formation in explants revealed no apparent decrease in proliferation or migration but revealed increases in cell retraction and death leading to reduced vessel growth and increased vessel regression. Consistent with this phenotype, ECs derived from mutant embryos exhibited aberrant lamellipodial extensions, altered actin cytoskeleton, and nonpolarized cell movement. This study reveals that FAK is crucial for vascular morphogenesis and the regulation of EC survival and morphology.     

The Hippo–YAP pathway regulates the proliferation of alveolar epithelial progenitors after acute lung injury

Regeneration of pulmonary epithelial cells plays an important role in the recovery of acute lung injury (ALI), which is defined by pulmonary epithelial cell death. However, the mechanism of the regenerative capacity of alveolar epithelial cells is unknown. Using a lung injury mouse model induced by hemorrhagic shock and lipopolysaccharide, a protein mass spectrometry‐based high‐throughput screening and linage tracing technology to mark alveolar epithelial type 2 cells (AEC2s), we analyzed the mechanism of alveolar epithelial cells proliferation. We demonstrated that the expression of Hippo‐yes‐associated protein 1 (YAP1) key proteins were highly consistent with the regularity of the proliferation of alveolar epithelial type 2 cells after ALI. Furthermore, the results showed that YAP1+ cells in lung tissue after ALI were mainly Sftpc lineage‐labeled AEC2s. An in vitro proliferation assay of AEC2s demonstrated that AEC2 proliferation was significantly inhibited by both YAP1 small interfering RNA and Hippo inhibitor. These findings revealed that YAP functioned as a key regulator to promote AEC2s proliferation, with the Hippo signaling pathway playing a pivotal role in this process.     

Studies on the lysine-binding sites of human plasminogen. The effect of ligand structure on the binding of lysine analogs to plasminogen

A method is described for measuring relative binding constants of lysine and analogs of lysine to plasminogen and plasminogen 'kringle' fragments. Plasminogen or kringle fragments adsorbed to lysine-Sepharose are eluted with increasing concentrations of lysine or other ligands, the concentration of ligand required to elute 50% of the protein being taken as a measure of the binding constant. The method is simple and is not dependent on monitoring conformational changes. We confirm earlier reports that the best ligands for the lysine binding sites of plasminogen are omega-amino acids containing five or six carbons. We show further that both Glu-plasminogen (the native form with N-terminal glutamic acid) and Lys-plasminogen (a degraded form with N-terminal lysine), as well as the heavy chain fragments, kringle 4 and kringle 1+2+3, have very similar properties with regard to binding specificity for omega-amino acids. For all species optimal binding is observed when the distance between the amino and carboxyl carbon is about 0.68 nm. The finding of ligands is decreased by the presence of polar atoms on the alpha and beta positions of the carbon chain of amino acids. Arginine binds relatively weakly at the lysine site and there does not appear to be a separate arginine binding site in plasminogen.