中国三种常见蒿属植物潜在地理分布及其主导气候因子

裂叶蒿(Artemisia tanacetifolia)、大籽蒿(Artemisia sieversiana)和艾(Artemisia argyi)是我国常见的蒿属(Artemisia)植物,其分布区域遍布全国.本文利用MaxEnt模型预测3种蒿属植物在当前气候条件以及未来两种气候情景下的潜在分布区.采用受试者工作特征...     

High throughput screening of hydrolytic enzymes from termites using a natural substrate derived from sugarcane bagasse

Background

Short rotation coppice willow is a potential lignocellulosic feedstock in the United Kingdom and elsewhere; however, research on optimising willow specifically for bioethanol production has started developing only recently. We have used the feedstock Salix viminalis × Salix schwerinii cultivar 'Olof' in a three-month pot experiment with the aim of modifying cell wall composition and structure within the stem to the benefit of bioethanol production. Trees were treated for 26 or 43 days with tension wood induction and/or with an application of the cellulose synthesis inhibitor 2,6-dichlorobenzonitrile that is specific to secondary cell walls. Reaction wood (tension and opposite wood) was isolated from material that had received the 43-day tension wood induction treatment.

Results

Glucan content, lignin content and enzymatically released glucose were assayed. All measured parameters were altered without loss of total stem biomass yield, indicating that enzymatic saccharification yield can be enhanced by both alterations to cell wall structure and alterations to absolute contents of either glucan or lignin.

Conclusions

Final glucose yields can be improved by the induction of tension wood without a detrimental impact on biomass yield. The increase in glucan accessibility to cell wall degrading enzymes could help contribute to reducing the energy and environmental impacts of the lignocellulosic bioethanol production process.     

长爪沙鼠发情周期规律与判定方法

目的研究长爪沙鼠发情周期,揭示发情规律,优化判定方法。方法连续18 d采集50只长爪沙鼠阴道上皮脱落细胞涂片,采用角化细胞计数法研究长爪沙鼠发情周期规律。比较瑞氏染色、HE染色和直接镜检判定发情周期4个时相的优缺点。结果长爪沙鼠的发情周期有稳定型、不稳定型、假孕三种类型。其中稳定型占68.6%,发情周期为(106.3±35.0)h,可分为4个时相。4个时相角化细胞的比例分别为发情前期(13.5±7.8)%、发情期(86.7±9.9)%、发情后期(27.9±12.8)%和发情间期(3.3±2.8)%。结论角化细胞计数能准确地判定长爪沙鼠的发情周期及各个时相。直接镜检法能快速反映阴道脱落细胞的形态。     

长爪沙鼠肝细胞体外分离培养体系的建立

目的建立长爪沙鼠原代肝细胞分离培养体系。方法以雄性长爪沙鼠为供体,采用组织消化法和Seglen两步灌流法分离肝细胞,以台盼蓝染色检测细胞得率和活率,过碘酸-希夫氏反应(PAS)鉴定肝细胞,倒置显微镜观察肝细胞形态变化,并使用含有多种细胞因子的培养基维持培养。结果组织消化法和Seglen两步灌流法平均每只长爪沙鼠可分别获得肝细胞(1.33±0.34)×107个、(3.97±1.15)×107个,细胞活率分别为(29.4±6.05)%、(80.3±4.56)%,这两种方法在细胞得率及活率方面存在显著差异。肝细胞内因有大量的糖原颗粒,经PAS染色后被染成红色。结果表明肝细胞在贴壁后72 h内,肝细胞形态发生显著变化。结论采用胶原酶经肝门静脉灌流分离肝细胞是一种高效获得肝细胞的方法。各种细胞因子有利于维持肝细胞在体外的生长分化,长爪沙鼠原代肝细胞分离培养体系的建立将为肝脏相关疾病研究和防治药物的开发提供技术支持。     

人TRAIL基因cDNA的克隆及其在COS—7细胞中的表达

ＴＲＡＩＬ(ＴＮＦｒｅｌａｔｅｄａｐｏｐｔｏｓｉｓｉｎｄｕｃｉｎｇｌｉｇａｎｄ)是最近克隆的肿瘤坏死因子(ＴＮＦ)家族的新成员,由于它的蛋白质结构和生物学效应类似于ＦＡＳ/ＡＰＯ1Ｌ,因此,也被称为ＡＰＯ2Ｌ。在低浓度下,ＴＲＡＩＬ能迅速地诱导多种肿瘤细胞系的?..     

SD雌性大鼠性发育早期性器官等脏器和性激素的动态变化

目的探讨正常SD雌性大鼠性成熟前不同日龄段的脏器与促黄体生成素（LH）、促卵泡素（FSH）、雌二醇（E2）等性激素的变化及其关系。方法从生产群中取出60窝密度状态一致的SD大鼠,在不同日龄随机选取雌性大鼠,检测15、25、32、40日龄时大鼠体重、主要脏器指数,子宫、卵巢组织变化和15、25、32、40、60日龄大鼠血清LH、FSH、E2水平。结果记录了SD雌性大鼠性成熟前各脏器指数和卵巢、子宫组织变化,结果显示大鼠卵巢、子宫的增长速度大于体重的增长,而其他脏器增速大都小于体重的增长。本研究还记录了血清LH、FSH、E2水平在不同日龄段的变化规律,表明血清LH、E2浓度在32日龄时出现较为明显升高。结论不同日龄大鼠脏器指数的动态变化提示大鼠性器官在性发育早期得到机体的优先发育。血清LH、E2水平在32日龄时有了明显升高,提示性腺轴功能已经激活。60日龄大鼠血清性激素水平的波动类似于动情周期的规律性变化,推测大鼠在60日龄前即已进入性成熟,这些结果将为大鼠性发育的相关研究提供重要的参考数据。     

Immunohistochemical detection of regulatory cells in the digestive system of leeches

The digestive system of four leech species,Glossiphonia complanata, Hirudo medicinalis, Haemopis sanguisuga, andErpobdella octoculata, was studied using, as markers, antisera to biologically active peptides, neurotensin, calcitonin, FRMF-amide, and serotonin. In the epithelium and the wall of the alimentary tract, regulatory cells were revealed. They differed in shapes and detected immunoreactivities; presumably they are elements of the diffuse endocrine system as well as of the peripheral nervous system. The data obtained show that the organization of the intestinal regulatory system in leeches basically is similar morphologically to intestinal regulatory systems of representatives of other classes of this type of invertebrate animals.     

Right- and left-loop short shRNAs have distinct and unusual mechanisms of gene silencing

Small hairpin RNAs (shRNAs) having duplex lengths of 25–29 bp are normally processed by Dicer into short interfering RNAs (siRNAs) before incorporation into the RNA-induced silencing complex (RISC). However, shRNAs of ≤19 bp [short shRNAs (sshRNAs)] are too short for Dicer to excise their loops, raising questions about their mechanism of action. sshRNAs are designated as L-type or R-type according to whether the loop is positioned 3′ or 5′ to the guide sequence, respectively. Using nucleotide modifications that inhibit RNA cleavage, we show that R- but not L-sshRNAs require loop cleavage for optimum activity. Passenger-arm slicing was found to be important for optimal functioning of L-sshRNAs but much less important for R-sshRNAs that have a cleavable loop. R-sshRNAs could be immunoprecipitated by antibodies to Argonaute-1 (Ago1); complexes with Ago1 contained both intact and loop-cleaved sshRNAs. In contrast, L-sshRNAs were immunoprecipitated with either Ago1 or Ago2 and were predominantly sliced in the passenger arm of the hairpin. However, ‘pre-sliced’ L-sshRNAs were inactive. We conclude that active L-sshRNAs depend on slicing of the passenger arm to facilitate opening of the duplex, whereas R-sshRNAs primarily act via loop cleavage to generate a 5′-phosphate at the 5′-end of the guide strand.