间断低氧对大鼠下丘脑超微结构及前增食欲素水平的影响

目的探讨睡眠中间断低氧对大鼠下丘脑前增食欲素及受体水平的影响以及下丘脑超微结构的变化。方法大鼠分成对照组、间断低氧组和持续低氧组,分别给予吸入空气,持续低氧和间断低氧气体,并在实验开始后1d、3d、1w和4w应用RT-PCR方法测定大鼠下丘脑前增食欲素及受体水平,分析其间的变化关系,电镜观察下丘脑的超微结构变化。结果与对照组和持续低氧组比较,间断低氧4w后大鼠下丘脑前增食欲素mRNA水平明显降低,受体水平升高,但在持续低氧和对照组之间无明显差异。在低氧后1d、3d、7d后大鼠下丘脑前增食欲素mRNA降低,受体水平升高,在4w后,持续低氧组则接近正常。急性持续低氧大鼠超微结构变化更严重,而慢性间断低氧变化更持久。结论慢性间断低氧可以引起下丘脑前增食欲素下降及受体水平升高,急性持续低氧也可引起上述变化,而慢性持续低氧未引起增食欲素改变;慢性间断低氧大鼠下丘脑超微结构表现为严重而持久的变化。     

An improved particle bombardment for the generation of transgenic plants by direct immobilization of relleasable Tn5 transposases onto gold particles

We have developed a modified particle bombardment method for plant transgenesis. An intein-tag and a 6×Cys-tag were successively fused to the N-terminus of a hyperactive Tn5 transposase. The modified transposase was immobilized on bare gold microscopic particles via covalent binding of a 6×Cys-tag sulfydryl groups to the gold surface. The tethered transposase can bind the transposon DNA in vitro to form the transposome in the absence of Mg2? ions. After bombardment of the gold particles carrying the transposomes into the plant cells, the transposomes will be released from the carrier due to the activated self-cleavage function of intein-tag. Our data showed this procedure integrated foreign DNA into the plant genome with an increased transformation frequency as compared to the conventional particle bombardment method. A single copy insertion can also be obtained by decreasing of the assembled transposon DNA amount in relation to plant cell biomass.     

新疆艾比湖和伊吾湖可培养嗜盐古菌多样性

新疆地区盐湖密布,蕴藏着丰富的微生物资源。为保护和利用微生物物种与基因资源,作者从新疆准噶尔盆地的艾比湖和天山山间盆地的伊吾湖分离纯化嗜盐微生物。采用PCR方法扩增其中65株嗜盐古菌16SrRNA基因序列。序列分析表明,分离的嗜盐古菌分属6个属,艾比湖以Haloterrigena和Natrinema属的菌株为主,伊吾湖由Haloarcula和Halorubrum两个属的菌株构成。通过多样性指数、丰富度指数、均匀度指数和物种相对多度模型对分离的菌株进行多样性分析和比较,结果表明,盐湖嗜盐古菌的多样性指数、丰富度指数和均匀度指数具有一定相关性,艾比湖可培养嗜盐古菌的多样性高于伊吾湖。研究发现了一些新的物种资源,表明新疆盐湖中孕育的特色微生物资源亟待保护与利用。     

Immune-related microRNAs are abundant in breast milk exosomes

Breast milk is a complex liquid rich in immunological components that affect the development of the infant's immune system. Exosomes are membranous vesicles of endocytic origin that are found in various body fluids and that can mediate intercellular communication. MicroRNAs (miRNAs), a well-defined group of non-coding small RNAs, are packaged inside exosomes in human breast milk. Here, we identified 602 unique miRNAs originating from 452 miRNA precursors (pre-miRNAs) in human breast milk exosomes using deep sequencing technology. We found that, out of 87 well-characterized immune-related pre-miRNAs, 59 (67.82%) are presented and enriched in breast milk exosomes (P < 10(-16), χ(2) test). In addition, compared with exogenous synthetic miRNAs, these endogenous immune-related miRNAs are more resistant to relatively harsh conditions. It is, therefore, tempting to speculate that these exosomal miRNAs are transferred from the mother's milk to the infant via the digestive tract, and that they play a critical role in the development of the infant immune system.     

天山冻土产低温脂肪酶菌株的筛选及其多样性分析

【目的】通过天山冻土细菌的分离和产低温脂肪酶菌株的筛选,了解天山冻土微生物的物种多样性和产脂肪酶菌株的系统发育多样性,为高效低温脂肪酶生物技术奠定基础。【方法】采用稀浓度的R2A、TSB平板涂布分离天山冻土中可培养细菌,通过选择性培养基筛选产低温脂肪酶的菌株。采用细菌常规生理生化实验、最适生长温度、耐盐性、产酶性能对分离菌株的生理学进行研究,通过16S rRNA基因序列分析确定产脂肪酶菌种的系统进化地位,通过BOX-PCR指纹技术对16S rRNA基因高度同源性的菌株进一步区分。【结果】分离筛选到78株可培养低温菌,选择培养基显示有17株可产低温脂肪酶,其中8株在两种选择培养基中均可产脂肪酶和酯酶。17株产酶菌分别隶属于5个系统发育类群、6个属,其中假单胞菌属(Pseudomonas)占大多数(58.9%)。【结论】天山冻土中产低温脂肪酶的细菌具有较丰富的系统发育多样性,依据生长温度,均属于耐冷菌。     

西南地区生态重要性格局研究

生态保护重要性是表征区域生态系统结构和功能重要性程度的综合指标。在明确西南地区自然环境特征和关键生态问题的基础上,综合分析生态敏感性和生态服务功能重要性,构建西南生态重要性评估指标体系,并运用GIS技术识别具有重要保护意义的地区,为优化生态保护策略、划定生态红线和主体功能区划提供技术支持。研究表明:西南地区生态保护极重要区为75.7万km2,主要分布于雅鲁藏布江流域、横断山区、川西高原等地区。该区占西南地区总面积的32.5%,提供了59.4%的土壤保持总量和54.5%的水源涵养总量,保护了69.7%的重要物种。研究建议,划定极重要区为生态红线进行强制性严格保护,以保障和维护生态安全,促进西南地区可持续发展。     

冻土甲烷循环微生物群落及其对全球变化的响应

冻土是陆地生态系统中最容易受到全球气候变化影响的碳库,既发挥着碳源又起着碳汇的作用。人们非常关注贮存于冻土中有机碳的最终归宿,是因为全球气候变暖会加快冻土的解冻,释放更多的温室气体（二氧化碳和甲烷）到大气中,从而进一步加剧温室效应。据估计每年从北半球冻原陆地生态系统释放进入大气的甲烷约占全球自然界释放甲烷总量的25%。研究证实冻土生物源甲烷的产生和消耗分别由耐(嗜)低温的产甲烷菌(methanogens)和甲烷氧化菌(methanotrophs)介导。鉴于冻土甲烷循环对全球甲烷平衡的显著作用以及在冻土生物地球化学循环中的重要功能,对介导冻土甲烷循环的产甲烷菌和甲烷氧化菌的研究将有助于更好地评估冻土生态系统对全球气候变化的响应和影响,本文就冻土甲烷循环过程、产甲烷菌、甲烷氧化菌的群落结构、活动、生态功能及其对气候和环境变化的响应机制的最新研究进行综述,以期为我国开展冻土甲烷循环机理研究提供支持。     

Gualou Xiebai Banxia decoction ameliorates Poloxamer 407-induced hyperlipidemia

Ethnopharmacological relevance: Gualou Xiebai Banxia (GLXBBX) decoction is a well-known traditional Chinese herbal formula that was first discussed in the Synopsis of the Golden Chamber by Zhang Zhongjing in the Eastern Han Dynasty. In traditional Chinese medicine, GLXBBX is commonly prescribed to treat cardiovascular diseases, such as coronary heart disease and atherosclerosis.Objective: The present study aimed to examine GLXBBX’s preventative capacity and elucidate the potential molecular mechanism of Poloxamer 407 (P407)-induced hyperlipidemia in rats.Materials and methods: Both the control and model groups received pure water, and the test group also received a GLXBBX decoction. For each administration, 3 ml of the solution was administered orally. To establish hyperlipidemia, a solution mixed with 0.25 g/kg P407 dissolved in 0.9% normal saline was injected slowly into the abdominal cavity. At the end of the study, the rats’ plasma lipid levels were calculated using an automatic biochemical analyzer to evaluate the preventative capability of the GLXBBX decoction, and the serum and liver of the rats were collected.Results: The GLXBBX decoction significantly improved P407-induced hyperlipidemia, including increased plasma triglycerides (TGs), aspartate aminotransferase (AST) elevation, and lipid accumulation. Moreover, GLXBBX decoction treatment increased lipoprotein lipase (LPL) activity and mRNA expression of LPL. Furthermore, GLXBBX significantly suppressed the mRNA expression of stearoyl-CoA desaturase (SCD1).Conclusion: GLXBBX significantly improved P407-induced hyperlipidemia, which may have been related to enhanced LPL activity, increased LPL mRNA expression, and decreased mRNA expression of SCD1.     

Erratum to: Research advances in expansins and expansin-like proteins involved in lignocellulose degradation

Biotechnology Letters -