短期增温对西藏念青唐古拉山典型植物群落结构和稳定性的影响

青藏高原气候变暖幅度显著高于全球其他区域,深刻影响着该地区植物群落的结构和稳定性。选择西藏念青唐古拉山的三种典型植物群落(高寒草原、高寒草甸和流石滩)作为研究对象,采用开顶式增温箱(OTC)模拟增温,研究了短期增温对植物群落结构和稳定性的影响。结果表明:(1)增温改变了群落的优势物种,影响其结构组成,而对物种多样性无显著影响;(2)增温显著降低了高寒草甸的地上生物量(P < 0.05),增加地下生物量(P < 0.01),从而导致了群落地下地上生物量分配策略的改变;(3)增温降低群落中部分物种的生态位宽度,进而影响群落稳定性,其中高寒草甸变化最大,达到-66.8%。研究结果可为青藏高原高寒草地生态系统应对和适应未来气候变化提供一定科学依据。     

利用生物质生产高效蛋白饲料的研究

本研究采用稀释分离法,从富含腐殖质土壤中,经反复筛选,选育出了四株酵母菌和二株霉菌。并分别对其进行了蛋白质、脂肪和纤维素酶活性以及菌体其它成份的测定。结果表明:L_(B-1)号和L_(B-3)号酵母菌蛋白质含量≥40％,其中L_(B-2)号酵母菌脂肪含量达到3.906％;而二株霉菌经固体发酵后测试证明:T_(B-1)号菌所产纤维素酶活性高于T_(B-2)号菌,最高酶活可达到1116.0毫克/克·小时。通过菌种最佳组合和液体——固体小型发酵试验生产的蛋白饲料达到了轻工部(QB596—82)饲料标准。从而说明,采用上述菌株、利用生物质(植物秸秆、味精废液)代替粮食作原料生产高效蛋白饲料是完全可行的。     

间接免疫荧光法鉴别小鼠早期胚胎性别的研究

以间接免疫荧光法检测昆明系小鼠早期胚胎雄性特异性H—Y抗原的表达。结果表明:54%的胚胎为H—Y阳性(雄性);46%为H—Y阴性(雌性)。经与昆明系小鼠的自然性比率(♂:52%;♀:48%)比较,两者无显著性差异。 经细胞遗传学方法确证,以免疫荧光法鉴别的胚胎性别,雄性的鉴别准确率为75.50%;雌性为82.97%。 本文还就影响鉴别准确率的若干因素以及本方法在生产中的应用前景等问题进行了分析讨论。     

Secretory expression of β-mannanase in Saccharomyces cerevisiae and its high efficiency for hydrolysis of mannans to mannooligosaccharides

Applied Microbiology and Biotechnology - Degradation of mannans is a key process in the production of foods and prebiotics. β-Mannanase is the key enzyme that hydrolyzes...     

Overexpression LINC01082 suppresses the proliferation,migration and invasion of colon cancer

The active form of vitamin D, 1,25-dihydroxycholecalciferol (1,25(OH)₂D₃), was reported to improve vascular function in patients with diabetes, yet the underlying mechanisms remain to be fully elucidated. Monoamine oxidase (MAO), a mitochondrial enzyme, with two isoforms (A and B) that generates hydrogen peroxide (H₂O₂) as by-product, has been recently reported to contribute to the pathogenesis of endothelial dysfunction in diabetes. The present study assessed the interaction between vitamin D and MAO in the vascular wall in the setting of type 1 experimental diabetes. To this aim, diabetes was induced in male Wistar rats via a single injection of streptozotocin (STZ, 50 mg/kg, IP) and 1 month later thoracic aortas were harvested and used for organ bath studies and H₂O₂ measurements. MAO expression was assessed by immunohistochemistry and RT-PCR. Endothelial function was evaluated in isolated aortic rings in the absence vs. presence of 1,25(OH)₂D₃ (100 nM, 24 h incubation). In diabetic animals, we found a significant reduction in the endothelial-dependent relaxation to acetylcholine and an increased expression of the MAO-A isoform, respectively. Vitamin D significantly improved vascular function, mitigated oxidative stress and decreased MAO-A expression in diabetic vascular preparations. In conclusion, MAO-A is induced in diabetic aortas and vitamin D can improve diabetes-induced endothelial dysfunction by modulating the MAO-A expression.

     

Design,synthesis and antimycobacterial activity of less lipophilic Q203 derivatives containing alkaline fused ring moieties

We report herein the design and synthesis of a series of less lipophilic Q203 derivatives containing an alkaline fused ring moiety. Most of them show considerable potency against MTB H37Rv strain (MIC?<?0.25?μM). Nine compounds (13, 15, 19, 21, 23, 25, 29, 35, 36) have the same excellent activity against both drug-sensitive and -resistant strains (MIC?<?0.035?μM) as Q203 and PBTZ169. Especially, compound 29 also displays acceptable safety, greater absorption in plasma and aqueous solubility than Q203, suggesting its promising potential to be lead compound for future antitubercular drug discovery.     

云南省两栖类物种名录修订

云南省是我国两栖类多样性最丰富的地区, 近年来受威胁的两栖类物种数显著增加, 亟需对两栖类的名录进行更新和完善。本文在《云南两栖爬行动物》的基础上, 通过收集近十余年的研究资料, 结合近年国内外最新研究结果, 确定物种有效性和分类归属, 并结合本团队野外考察数据, 对云南两栖类的物种名录和分布进行系统的整理与修订。修订后的名录共记录云南省两栖类191种, 隶属3目12科49属, 占全国两栖类种数的32.5%。自2008年以来, 云南省新增两栖类1科23属70种, 本名录修订3科31属47种; 共发现34个新种、15个中国新纪录和10个省级新纪录种, 主要集中在云南的边境地区。云南省记录45种受威胁物种, 占云南省两栖类种数的23.6%, 占全国受威胁两栖类物种数的25.6%。其中, 2种被列为极危(CR), 9种被列为濒危(EN), 34种被列为易危(VU)。名录共记录15种国家II级重点保护野生动物, 占受国家保护两栖类种数的16.0%。此外, 列入CITES附录I和附录II的分别有1种和8种, 被列为云南省极小种群物种而作为重点保护野生动物的有5种。在新名录的基础上, 本文讨论了云南省两栖类多样性与分类研究不足的类群、考察薄弱的地区、物种丰富度的格局分布以及受威胁情况, 以期对云南省未来两栖类的研究和保护工作提供依据和参考。     

黄瓜卷须缠绕过程中小G蛋白活性变化

攀爬植物的卷须是对机械刺激极为敏感的器官。拟南芥(Arabidopsis thaliana)小G蛋白能够响应机械刺激调控自身发育, 但小G蛋白信号是否在卷须感受机械刺激发生缠绕过程中发挥作用目前尚不清楚。该研究以黄瓜(Cucumis sativus)为实验材料, 对其卷须受机械刺激缠绕过程中小G蛋白活性进行了探讨。ROP活性检测结果表明, 在卷须缠绕过程中小G蛋白CsROP6的活性显著增强; 同时, 质谱鉴定结果显示, 卷须缠绕过程中生长素的含量明显增加。进一步的实验表明, 外源生长素处理能明显增强CsROP6的活性, 暗示黄瓜卷须在缠绕过程中受机械刺激可能通过生长素增强ROP活性, 且机械刺激激活小G蛋白信号在不同植物中存在一定的保守性。     

De novo synthesis,constitutive expression of <Emphasis Type="Italic">Aspergillus sulphureus</Emphasis> β-xylanase gene in <Emphasis Type="Italic">Pichia pastoris</Emphasis> and partial enzymic characterization

The endo-β-1, 4-xylanase gene xynA from Aspergillus sulphureus, encoded a lack-of-signal peptide protein of 184 amino acids, was de novo synthesized by splicing overlap extension polymerase chain reaction according to Pichia pastoris protein’s codon bias. The synthetic DNA, composed of 572 nucleotides, was ligated into the downstream sequence of an α-mating factor in a constitutive expression vector pGAPzαA and electrotransformed into the P. pastoris X-33 strain. The transformed yeast screened by Zeocin was able to constitutively secrete the xylanase in yeast–peptone–dextrose liquid medium. The heterogenous DNA was stabilized in the strain by 20-times passage culture. The recombinant enzyme was expressed with a yield of 120 units/mL under the flask culture at 28°C for 3 days. The enzyme showed optimal activity at 50°C and pH 2.4–3.4. Residual activity of the raw recombinant xylanase was not less than 70% when fermentation broth was directly heated at 80°C for 30 min. However, the dialyzed xylanase supernatant completely lost the catalytic activity after being heated at 60°C for 30 min. The recombinant xylanase showed no obvious activity alteration by being pretreated with Na₂HPO₄-citric acid buffer of pH 2.4 for 2 h. The xylanase also showed resistance to certain metal ions (Na⁺, Mg²⁺, Ca²⁺, K⁺, Ba²⁺, Zn²⁺, Fe²⁺, and Mn²⁺) and EDTA. These biochemical characteristics suggest that the recombinant xylanase has a prospective application in feed industry as an additive.     

Mec1/Tel1 phosphorylation of the INO80 chromatin remodeling complex influences DNA damage checkpoint responses

The yeast Mec1/Tel1 kinases, ATM/ATR in mammals, coordinate the DNA damage response by phosphorylating proteins involved in DNA repair and checkpoint pathways. Recently, ATP-dependent chromatin remodeling complexes, such as the INO80 complex, have also been implicated in DNA damage responses, although regulatory mechanisms that direct their function remain unknown. Here, we show that the Ies4 subunit of the INO80 complex is phosphorylated by the Mec1/Tel1 kinases during exposure to DNA-damaging agents. Mutation of Ies4's phosphorylation sites does not significantly affect DNA repair processes, but does influence DNA damage checkpoint responses. Additionally, ies4 phosphorylation mutants are linked to the function of checkpoint regulators, such as the replication checkpoint factors Tof1 and Rad53. These findings establish a chromatin remodeling complex as a functional component in the Mec1/Tel1 DNA damage signaling pathway that modulates checkpoint responses and suggest that posttranslational modification of chromatin remodeling complexes regulates their involvement in distinct processes.