一种快速提取肠道微生物总DNA的方法

采集的兔肠道内容物及其粪便样品,通过分散浸泡、震荡洗涤、分级离心、滤器过滤、DNA提取试剂盒提取纯化,可以获得纯度很高的DNA样品。经0.8%琼脂糖凝胶电泳检测和紫外分光光度计测定,样品A260/A280的比值为1.72±0.02。分别以提取的DNA样品为模板,通过设计的细菌特异引物,对其16S rDNA基因进行PCR扩增,获得了1.6 kb大小特异性很好的预期条带。这为肠道微生物群落的分子生态学研究提供了一种简便、可靠的DNA提取方法。     

昆明地区昭觉林蛙不同发育期蝌蚪的栖息地利用

通过观察昭觉林蛙(Ranachaochiaoensis)蝌蚪在栖息地的分布状况,统计和分析不同发育期蝌蚪在不同植被盖度、水深和水温下的分布频次。其结果表明,Ⅰ、Ⅱ期蝌蚪更倾向于选择植被盖度为41%—70%的水域;Ⅲ期蝌蚪对植被盖度的选择不明显。Ⅱ期蝌蚪倾向于选择水深为0·11—0·30m的水域;Ⅰ、Ⅲ期蝌蚪对水深的选择不明显,且Ⅲ期蝌蚪在水深大于0·31m的水域无分布。随着蝌蚪生长发育,Ⅰ期至Ⅲ期对水深的选择不断变浅。Ⅰ、Ⅱ期蝌蚪均倾向于选择水温为19—25℃的水域;Ⅲ期蝌蚪对水温的选择不明显,但在水温为8—13℃的水域无分布。     

诺卡氏菌形放线菌β-甘露聚糖酶的水解特性

诺卡氏菌形放线菌（Nocardioform actinomycetes）NA3-540产生的β-甘露聚糖酶（ManNA）能不同程度地水解槐豆胶、瓜胶、田菁胶和魔芋胶等甘露多聚糖为组分的植物胶,生成系列甘露寡糖;该酶只轻微地水解香豆胶,不能水解β-甘露聚糖、黄原胶、海藻胶;ManNA对槐豆胶、瓜胶和魔芋胶多糖的Km值和Vmax分别为1．75、6．13、3．9mg／mL和2485、1303、853μmol／（min／mg）,表明槐豆胶是该酶的理想水解底物。ManNA水解几种植物胶的明显差异,表明甘露聚糖的糖链组成和空间结构明显地影响着β-甘露聚糖酶的水解活性。     

镉对小鼠精子和生精细胞超微结构及生精细胞bcl-2、bax基因表达的影响

研究镉暴露对小鼠附睾精子和睾丸生精细胞超微结构的变化以及镉对生精细胞凋亡相关基因bcl-2、bax表达水平的影响。采用24只雄性ICR小鼠随机分为4组,每组6只,分别以0.183、0.915、1.83mg/kg氯化镉腹腔注射,每天1次,连续5次,设阴性对照生理盐水组。于第6天透射电镜观察附睾精子超微结构、睾丸生精细胞核和线粒体超微结构的变化,免疫组化方法检测生精细胞Bcl-2、Bax表达水平。透射电镜观察显示,0.183mg/kg组精子超微结构无显著性变化,0.915mg/kg组精子头部两侧膜与头部胞质间隙轻微扩大,线粒体嵴间腔扩大且轻度空泡化,但与对照组相比无统计学意义(P>0.05)。1.83mg/kg组头部两侧膜与胞质间隙扩大,与对照组相比有显著性差异(P<0.05),尾部线粒体嵴间腔扩大且轻度空泡化,与对照组相比有显著性差异(P<0.05)。3种剂量处理组睾丸生精细胞核超微结构异常发生率显著高于对照组(P<0.05),且随着处理浓度的升高异常发生率升高;1.83mg/kg组线粒体肿胀空泡化发生率显著高于对照组(P<0.05)。3种剂量实验组生精细胞Bcl-2表达水平(吸光度)显著低于对照组(P<0.01),0.915mg/kg组Bax表达水平显著高于对照组和0.183、1.83mg/kg组(P<0.01)。3种剂量实验组Bcl-2/Bax吸光度比值显著低于对照组(P<0.01);0.915mg/kg组Bcl-2/Bax比值显著低于1.83mg/kg组(P<0.01)。上述结果提示:高浓度镉诱导附睾精子超微结构改变,高中低浓度镉致睾丸生精细胞超微结构的改变,生精细胞超微结构发生凋亡现象。镉对Bcl-2、Bax表达水平的改变可能是生精细胞凋亡的分子机制之一。     

NHE1 mediates MDA-MB-231 cells invasion through the regulation of MT1-MMP

Na⁺/H⁺ exchanger 1 (NHE1), an important regulator of intracellular pH (pH_i) and extracellular pH (pH_e), has been shown to play a key role in breast cancer metastasis. However, the exact mechanism by which NHE1 mediates breast cancer metastasis is not yet well known. We showed here that inhibition of NHE1 activity, with specific inhibitor Cariporide, could suppress MDA-MB-231 cells invasion as well as the activity and expression of MT1-MMP. Overexpression of MT1-MMP resulted in a distinguished increase in MDA-MB-231 cells invasiveness, but treatment with Cariporide reversed the MT1-MMP-mediated enhanced invasiveness. To explore the role of MAPK signaling pathways in NHE1-mediated breast cancer metastasis, we compared the difference of constitutively phosphorylated ERK1/2, p38 MAPK and JNK in non-invasive MCF-7 cells and invasive MDA-MB-231cells. Interestingly, we found that the phosphorylation levels of ERK1/2 and p38 MAPK in MDA-MB-231 cells were higher than in MCF-7 cells, but both MCF-7 cells and MDA-MB-231 cells expressed similar constitutively phosphorylated JNK. Treating MDA-MB-231 cells with Cariporide led to decreased phosphorylation level of both p38 MAPK and ERK1/2 in a time-dependent manner, but JNK activity was not influenced. Supplementation with MAPK inhibitor (MEK inhibitor PD98059, p38 MAPK inhibitor SB203580 and JNK inhibitor SP600125) or Cariporide all exhibited significant depression of MDA-MB-231 cells invasion and MT1-MMP expression. Furthermore, we co-treated MDA-MB-231 cells with MAPK inhibitor and Cariporide. The result showed that Cariporide synergistically suppressed invasion and MT1-MMP expression with MEK inhibitor and p38 MAPK inhibitor, but not be synergistic with the JNK inhibitor. These findings suggest that NHE1 mediates MDA-MB-231 cells invasion partly through regulating MT1-MMP in ERK1/2 and p38 MAPK signaling pathways dependent manner.     

对从面包中筛选酵母菌及其发酵特性的研究

目的 从野生酵母筛选出对可溶性糖产生既可氧化又可还原、并发生反式反应的酵母菌株,使其能应用于相关物质的生物合成.方法 对从面包中滋生出多种的野生菌落采用依形态、使易糖氧化为主要特征筛选出野生酵母菌落.结果 从3株野生菌株(JM1、JM2、JM3)中筛选出JM1,该菌株能使体内发生反式催化的氧化反应.结论 该菌株适宜的生...     

Effect of long-term exposure to simulated acid rain on the development and reproduction of the predatory mite, <Emphasis Type=Italic>Euseius nicholsi</Emphasis> (Ehara <Emphasis Type=Italic>et</Emphasis> Lee) (Acari: Phytoseiidae)

The effects of simulated acid rain on the development and reproduction of E. nicholsi, an important natural enemy of many species of pest mites in China, were studied in the laboratory. The life history parameters of E. nicholsi were investigated after long-term (about 8 generations) exposure to various levels of simulated acid rain (pH 2.0, 3.0, 4.0, and 5.6). The results showed that the acid rain had negative effects on some basic parameters of the life history of the E. nicholsi population indirectly. The whole development durations with pH 3.0–5.6 treatments were longer and the duration with pH 2.0 treatment was shorter than with deionized water treatments (control). Adult longevity and oviposition duration were notably shortened, and female fecundity was decreased by an increase in acidity. The net reproductive rate (R ₀) of the populations treated with acid rain was less than that of the control populations and gradually decreased with an increase in acidity; however, the values of the intrinsic rate of increase (r) were not affected significantly by acid rain, and inhibitory effects of acid rain on the population growth of E. nicholsi were not recognized.     

基于MSPA和MCR模型的秦岭(陕西段)山地生态网络构建

快速的城市化发展破坏了生境斑块的连通性,而在应对此环境变化中,从斑块层构建区域生态网络的研究不足.本研究以秦岭(陕西段)为对象,采用形态学空间格局分析(MSPA)辨别生态源地,利用最小阻力模型(MCR)提取潜在生态廊道,构建秦岭生态网络;基于重力模型对生态网络内部斑块的重要性进行分级,并分析了网络的结构特征及景观构成....     

Equilibrium vitrification of mouse embryos at various developmental stages

Previously, we developed a new method by which 2‐cell mouse embryos can be vitrified in liquid nitrogen in a near‐equilibrium state, and then kept at ?80°C for several days. In the present study, we examined whether or not the method was effective for mouse embryos at other developmental stages. Eight‐cell embryos, morulae, and expanded blastocysts of ICR mice were vitrified with ethylene glycol‐based solutions, named EFSc because of their composition of ethylene glycol (30–40%, v/v) and FSc solution. The FSc solution was PB1 medium containing 30% (w/v) Ficoll PM‐70 plus 1.5 M sucrose. The extent of equilibrium was assessed by examining how well vitrified embryos survived after being kept at ?80°C. When 8‐cell embryos and morulae were vitrified with EFS35c or EFS40c and then kept at ?80°C, the survival rate was high even after 4 days in storage and remained high after re‐cooling in liquid nitrogen. On the other hand, the survival of vitrified‐expanded blastocysts kept at ?80°C was low. Therefore, 8‐cell embryos and morulae can be vitrified in a near‐equilibrium state using the same method as for 2‐cell embryos. A high proportion of C57BL/6J embryos at the 2‐cell, 8‐cell, and morula stages vitrified with EFS35c developed to term after transportation on dry ice, re‐cooling in liquid nitrogen, and transfer to recipients. In conclusion, the near‐equilibrium vitrification method, which is effective for 2‐cell mouse embryos, is also effective for embryos at the 8‐cell and morula stages. The method would enable handy transportation of vitrified embryos using dry ice. Mol. Reprod. Dev. 79: 785–794, 2012. © 2012 Wiley Periodicals, Inc.     

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.