金黄色葡萄球菌噬菌体vB_Sau_P68的基因组分析和裂解酶

【背景】金黄色葡萄球菌是常见的人畜共患条件致病菌,随着多耐药菌株分离率的增长,研发与抗生素作用模式不同的抗菌剂迫在眉睫。【目的】分离高效且特异性强的金黄色葡萄球菌噬菌体,对其进行功能注释,并对其编码的裂解酶进行功能验证。【方法】通过对噬菌体全基因组序列进行分析找到裂解酶基因,利用原核表达系统对其编码的2个裂解酶蛋白进行克隆,用SDS-PAGE与蛋白免疫印迹法(Western blotting)鉴定目的蛋白是否表达,并采用单斑法验证其裂解活性。【结果】本研究的噬菌体为一株新的金黄色葡萄球菌噬菌体,命名为vB＿Sau＿P68,该基因组全长为139 409 bp,GC含量为31.0%,编码220个开放阅读框(open reading frame,ORF),透射电镜观察具有正二十面体头部和收缩性尾部,形态学分类属于肌尾噬菌体。该噬菌体编码2个裂解酶基因,分别具有CHAP催化结构域与SH3＿5结合结构域,SDS-PAGE与Western blotting表明Lys161能够表达且有裂解活性,Lys163则无法外源表达。对Lys161序列进行分析,该裂解酶无信号肽,无跨膜区域,以无规则卷曲为主。【...     

Anti-idiotype induction therapy: anti-CA125 antibodies (Ab3) mediated tumor killing in patients treated with Ovarex mAb B43.13 (Ab1)

 Intravenous injection of the murine monoclonal anti-CA125 antibody B43.13 (Ovarex: Ab₁) into ovarian cancer patients led to the induction of an idiotypic network. Of the 75 patients who received one to ten injections of a 2-mg dose of the antibody, 48 developed anti-(mAb B43.13) antibodies (Ab₂); 18 of these patients also had elevated levels of anti-[anti-(mAb B43.13)] antibodies (Ab₃; = anti-CA125 antibodies) compared to pre-injection values. Characterization of these antibodies revealed that the binding to CA125 could be inhibited by mAb B43.13 in most samples. Human anti-CA125 antibodies or Ab₃ purified from patient serum samples specifically recognized human ovarian tumor cells and tissues expressing CA125. In addition, these anti-CA125 antibodies were able to conduct F_c-mediated tumor cell killing (antibody-dependent cell-mediated cytotoxicity). This raises the possibility of using an Ab₁ for anti-idiotype induction immunotherapy of cancer. Received: 14 October 1997 / Accepted: 9 January 1998     

A prominent β-hairpin structure in the winged-helix domain of RECQ1 is required for DNA unwinding and oligomer formation

RecQ helicases have attracted considerable interest in recent years due to their role in the suppression of genome instability and human diseases. These atypical helicases exert their function by resolving a number of highly specific DNA structures. The crystal structure of a truncated catalytic core of the human RECQ1 helicase (RECQ1(49-616)) shows a prominent β-hairpin, with an aromatic residue (Y564) at the tip, located in the C-terminal winged-helix domain. Here, we show that the β-hairpin is required for the DNA unwinding and Holliday junction (HJ) resolution activity of full-length RECQ1, confirming that it represents an important determinant for the distinct substrate specificity of the five human RecQ helicases. In addition, we found that the β-hairpin is required for dimer formation in RECQ1(49-616) and tetramer formation in full-length RECQ1. We confirmed the presence of stable RECQ1(49-616) dimers in solution and demonstrated that dimer formation favours DNA unwinding; even though RECQ1 monomers are still active. Tetramers are instead necessary for more specialized activities such as HJ resolution and strand annealing. Interestingly, two independent protein-protein contacts are required for tetramer formation, one involves the β-hairpin and the other the N-terminus of RECQ1, suggesting a non-hierarchical mechanism of tetramer assembly.     

Spread of the autonomous transposable element hobo in the genome of Drosophila melanogaster

The transposable element hobo has been introduced into the previously empty Drosophila melanogaster strain Hikone so that its dynamics can be followed and it can be compared with the P element. Five transformed lines were followed over 58 generations. The results were highly dependent on the culture temperature, the spread of hobo element being more efficient at 25 degrees C. The multiplication of hobo sequences resulted in a change in the features of these lines in the hobo system of hybrid dysgenesis. The number of hobo elements remained low (two to seven copies) and the insertions always corresponded to complete sequences. Our findings suggest that, despite their genetic similarities, P and hobo elements differ in many aspects, such as mobility and regulation mechanisms.      

湖南省爬行类一新纪录属——棱蜥属Tropidophorus

记述了采自湖南洪江市雪峰山的广西棱蜥(Tropidophorus guangxiensis Wen,1992),是在湖南的首次记录,同时棱蜥属(Tropidophorus DumrilBibron,1839)也是湖南的新纪录属。标本现藏于湖南师范大学动物标本馆。     

基孔肯雅病毒囊膜蛋白假病毒模型的构建

目的:以HIV为骨架构建单次复制性的含基孔肯雅病毒囊膜蛋白的假病毒模型,观察其对哺乳动物细胞的侵染性。方法:PCR合成基孔肯雅病毒囊膜蛋白基因,克隆到真核表达载体上,与HIV慢病毒包装系统质粒共转染293FT细胞,48 h后收培养上清,在8μg/mL Polybrene存在下感染293FT细胞,感染48 h后在荧光显微镜下观察结果。结果:PCR合成了基孔肯雅病毒囊膜蛋白基因并克隆到真核表达载体上,测序结果正确;共转染293FT细胞后,检测到基孔肯雅病毒囊膜蛋白的表达并包装成假病毒,感染新鲜293FT细胞后能够检测到绿色荧光蛋白。结论:合成的基孔肯雅病毒囊膜蛋白基因能正确表达并包装成假病毒,含基孔肯雅病毒囊膜蛋白的假病毒能感染293FT细胞并表达绿色荧光蛋白,可用该假病毒模型进一步研究基孔肯雅病毒的感染性,筛选评价抗基孔肯雅病毒药物。     

干旱胁迫下喷施黄腐酸对燕麦光合及其抗氧化酶活性的影响

为了揭示黄腐酸对干旱胁迫下燕麦光合及其抗氧化酶活性的影响机理,该研究选用燕麦品种‘燕科2号’为材料,采用盆栽试验,以正常供水(田间持水量的75%)为对照(CK),设干旱胁迫处理(田间持水量的45%,D0)、D0+喷施不同浓度黄腐酸(0、200、400、600、800、1000 mg/L)处理(D1~D5),测定各处理燕麦干鲜重、光合性能及其抗氧化酶活性。结果表明:(1)与CK相比,干旱胁迫下燕麦幼苗地上部鲜重和干重、叶片光合色素含量、净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)均显著降低,并导致叶片F_v/F_m、q P、ETR和ΦPSⅡ显著下降,使叶片抗氧化酶SOD、POD、CAT活性分别显著提高25.68%、19.98%和7.29%。(2)与D0相比,D0+喷施600 mg/L黄腐酸后,燕麦幼苗地上部鲜重和干重分别显著提高了28.59%和39.13%,叶片叶绿素a、叶绿素a+b、类胡萝卜素和P_n、G_s、T_r及F_v/F_m、ΦPSⅡ、ETR分别显著增加了25.17%、21.03%、47.37%和74.38%、26.47%、43.34%及6.49%、69.57%、70.71%,C_i和F_o、NPQ分别显著降低了19.52%和13.32%、43.75%。(3)干旱胁迫下喷施不同浓度的黄腐酸均使幼苗叶片中SOD、POD、CAT活性较D0处理显著增加,其中喷施600 mg/L黄腐酸的叶片SOD、POD、CAT活性最高,分别较D0处理显著增加了12.19%、76.57%和55.26%。研究认为,叶面喷施适宜浓度黄腐酸能够显著提高干旱胁迫下燕麦幼苗的光合作用及其抗氧化能力,缓解干旱对燕麦幼苗的伤害,进而促进燕麦幼苗的生长,且以叶面喷施600 mg/L黄腐酸效果最佳。     

瓯江干流丽水段渔业资源群落结构的季节变化

根据2009年春(3月)、夏(6月)、秋(9月)、冬(12月)瓯江干流丽水段(28°16′47.03″N—28°24′42.66″N、119°42′31.41″E—119°57′13.03″E)的渔业资源调查资料,对瓯江干流丽水段鱼类的资源状况、重要种类的生态优势度、多样性指数、群落结构等动态变化进行了分析。结果表明:瓯江干流丽水段现有鱼类47种、隶属于5目、12科、34属,较1972年的66种减少了28.8%;四季全部调查水域中出现的优势鱼种有圆吻鲴、大眼华鳊、黄颡、唇鱼骨、圆尾鮠、江黄颡、薄颌光唇鱼和鲤8种,其中圆吻鲴和大眼华鳊为常年优势种,其他6种为某一季节的优势种;不同季节优势度变化范围为0.578～0.747,以冬季最高;Margalef指数(D)介于2～4,Shannon指数(H)介于1～2,Pielou均匀度指数(J)介于0.3～0.6,依此判定瓯江干流丽水段渔业资源群落的多样性属于正常水平。群落季节更替指数和迁移指数揭示该流域鱼类群落结构具有明显季节性变化,而群落相似性指数(Jaccard指数和Sorenson指数)揭示3个生境的鱼类种群相似度均属于中等不相似。     

初生赛加羚羊部分生物学指标的观测与分析

2018年4月下旬至5月初对国家林业局甘肃濒危动物保护中心的61只初生赛加羚羊(Saiga tatarica)成活率、性别比例、单双羔比例、初生重等生物学数据进行了观测,并对结果进行归纳分析。赛加羚羊分娩期始于4月25日,截止于5月5日,产羔高峰期集中在4月28日至5月2日。共分娩61只羔羊,成活56只,成活率91.80%。其中,雄性羔羊占40.98%,雌性羔羊占59.02%,雌雄性别比(♀︰♂)为1.44︰1,与1︰1的性比差异不显著(χ2检验,P> 0.05);单羔比例80.33%,双羔比例19.67%,两者差异极显著(P <0.01);初生羔羊体重多数集中在2.501～3.000 kg,雄性羔羊平均初生重略高于雌性羔羊,单羔羚羊平均体重略高于双羔羚羊。单羔雄羚羊与双羔雄羚羊、单羔雌羚羊与双羔雌羚羊以及单双羔、雌雄羔羊总平均体重间的差异均不显著(P> 0.05)。     

干旱胁迫下腐植酸对燕麦叶片非结构性碳水化合物代谢的影响

以燕麦品种‘燕科2号’为试验材料,采用盆栽方式,分别在正常供水(75%田间持水量)、中度干旱胁迫(60%田间持水量)和重度干旱胁迫(45%田间持水量)3个水分条件下喷施腐植酸(HA)和等量清水(CK),对燕麦叶片中非结构性碳水化合物(NSC)含量及相关酶活性和籽粒产量进行测定,以明确腐植酸在干旱胁迫下对燕麦叶片非结构性碳水化合物代谢变化的影响,探讨HA对燕麦耐旱性的影响及其作用机制。结果表明：(1)随着土壤水分含量的减少,燕麦叶片中蔗糖和淀粉含量逐渐显著降低,蔗糖合成酶(SS)、蔗糖磷酸合成酶(SPS)活性显著降低,而酸性转化酶(S AI)和淀粉水解酶(α GC)活性显著提高。(2)燕麦叶片可溶性总糖和还原糖含量随着土壤水分含量的减少表现出先升高后降低的变化趋势,导致籽粒产量显著下降,且干旱胁迫程度越重变化幅度越大。(3)叶面喷施HA能不同程度提升中度和重度干旱胁迫下燕麦叶片中上述非结构性碳水化合物含量,并调节相关酶活性,显著提高籽粒产量,并在重度胁迫下的效果更佳。研究发现,腐植酸可以通过调控燕麦叶片NSC的代谢来响应干旱胁迫,降低叶片细胞渗透势,有效缓解干旱胁迫造成的损伤,增强植株耐旱性。