Cytological studies on the genus Holcoglossum (Orchidaceae)

The karyotypes of ten species of Holcoglossum (Orchidaceae), a highly endangered and diversified genus from China, were investigated to study the infrageneric relationships, biogeography, and speciation patterns in the Hengduan Mountains. The karyotype formulae of the studied species are as follows: 2 n  = 38 = 20m + 18sm in H. subulifolium , 2 n  = 38 = 22m + 16sm in H. amesianum , 2 n  = 38 = 26m + 12sm (6 SAT) in H. lingulatum , 2 n  = 38 = 26m + 12sm in H. wangii , 2 n  = 38 = 10m + 28sm in H. kimballianum , 2 n  = 38 = 14m + 22sm + 2st in H. flavescens , 2 n  = 38 = 24m + 12sm + 2st in H. rupestre , 2 n  = 38 = 14m + 20sm + 4st in H. sinicum , 2 n  = 38 = 16m + 14sm + 8st in H. weixiense , and 2 n  = 76 in H. tsii . The karyotypes of two tropical species, H. amesianum and H. subulifolium , are the most primitive in the genus, whereas those of four temperate alpine species, H. sinicum , H. rupestre , H. weixiense , and H. flavescens , are more advanced. H. tsii is a tetraploid and H. rupestr e may be one of its ancestors. The low frequency of polyploidy in Holcoglossum in the Hengduan Mountains region supports the conclusion that chromosome stasis during rapid speciation is common there.  © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 283–288.     

魏氏拟尾柱虫腹皮层纤毛器微管胞器的形态及形态发生

应用荧光紫杉醇直接荧光标记和抗α-微管蛋白抗体免疫荧光标记显示,魏氏拟尾柱虫(Paraurostyla weissei)腹面皮层纤毛器微管胞器由口围带、波动膜、额腹横棘毛和左右缘棘毛等纤毛器微管、纤毛器基部附属微管等组成。其中口围带基部微管包括小膜托架、小膜附属微管;额腹横棘毛和左右缘棘毛基部附属微管包括前纵微管束、后纵微管束和横微管束,它们由各自的纤毛器基部向皮层细胞质不同方向发射,形成腹皮层表面下微管网。结果表明,魏氏拟尾柱虫的纤毛器骨架、纤毛器附属结构也是一类以微管蛋白为基本成分的微管胞器,其中缘棘毛基部附属微管具有不同于其他纤毛虫(例如棘尾虫)中所观察到的同种微管胞器的建构特征。形态发生中,前仔虫口围带在老结构位置形成,其结构建成与部分老口围带的更新有关;老缘棘毛的结构物质对新的左、右缘棘毛的发生可能具有定位作用及物质贡献,但此后新的左、右缘棘毛列分别在老缘棘毛的右侧形成,而并非是在老缘棘毛位置分化的。在有些细胞中,新的左缘棘毛左侧另有一列棘毛,这可能是形态发生中老的左缘棘毛退化不完全产生的。     

鸡骨常山属三个种的核形态

研究了鸡骨常山属（Alstonia）3个种的核形态,其中盆架树（A.rostrata）的核型属首次报道,3个种的体细胞染色体数目均为2n=42,且糖胶树（A.scholaris）和鸡骨常山（A.yunnanensis）的染色体数目同前人报道的2n=44不同。盆架树的间期核和有丝分裂前期染色体分别为棒状前染色体型和中间型,核型公式为2n=42=3M＋21m＋18sm,核型不对称性类型为2A型。糖胶树的间期核和有丝分裂前期染色体分别为球状前染色体型和中间型,核型公式为2n=42=14m＋24sm＋4st,核型不对称性类型为3A型。鸡骨常山的间期核和有丝分裂前期染色体分别为复杂染色体中央粒型和中间型,核型公式为2n=42=5m＋37sm,核型不对称性类型为3B型。根据核形态结果,结合形态学特征和已有的细胞学资料,初步讨论了该属几个种的系统位置及演化趋势。     

外源氮对沼泽湿地CH4和N2O通量的影响

三江平原沼泽湿地受到大气沉降、地表径流、农业排水等外源氮素的输入,对湿地生态系统CH4和N2O通量有重要影响。采用野外原位施肥试验模拟外源氮输入,设0,60,120,240kgN·hm^-24种试验处理,探讨外源氮对沼泽湿地CH4和N2O通量的影响。结果表明,外源氮促进了CH4和N2O排放。与对照处理比较,各施氮水平CH4平均排放通量分别增加了181％,254％和155％,N2O排放通量分别增加了21％,100％和533％。外源氮输入对CH4排放的季节变化形式影响不大,而N2O的季节变化形式随着氮输入表现出波动变化的趋势。不同施氮水平对CH4排放的促进作用与植物生长阶段和产CH4的微生物过程密切相关,N2O排放通量随氮输入量呈指数增加（R^2=0．97,P〈0．01）。外源氮通过影响湿地微生物过程来进一步影响CH4和N2O的排放。     

SPF级金黄地鼠的主要生物学特性

目的测定SPF级金黄地鼠的生物学特性数据,为生物制品的生产、检定及科学研究提供标准化的SPF级金黄地鼠。方法在5周龄、10周龄和30周龄群体中随机抽样20只地鼠,雌雄各半。测定生长发育、繁殖性能、淘汰种鼠干物质及粗脂肪含量、解剖学特性以及血液生理生化指标等生物学特性指标。结果从SPF级金黄地鼠的生长和繁殖特性来看,通过严格的选择和淘汰,SPF级金黄地鼠的生长、繁殖等特性已保留下来,同比原种群得到进一步提高。其体重和主要脏器重量、脏器系数的数据在5、10和30这三个日龄段基本稳定一致,呈现正常的生长规律;该鼠群的血常规、血液生化指标和免疫指标也比较稳定一致,个体间的差异很小。结论本实验测定的SPF级金黄地鼠的主要生物学特性,将为SPF级金黄地鼠进一步标准化提供极其重要的依据。     

组织工程静脉血管种子细胞的培养

目的获取可应用于静脉血管组织工程的种子细胞内皮细胞。方法选取北京地区雄性杂种犬,取其双侧颈外静脉,采用翻转后酶消法,获取原代内皮细胞,对其进行原代培养和传代培养,冻存、复苏和鉴定,并利用光学显微镜进行观察。结果获取犬的颈外静脉后,实验采取了翻转后酶消法,所获得的内皮细胞纯度和数量得到了提高;经过鉴定确实为内皮细胞来源;活性好,增殖快,在较短的时间内能够达到后期实验所需数量。结论经体外培养的犬的颈外静脉内皮细胞可以作为组织工程血管的种子细胞。     

HBV YIDD变异株真核表达载体的构建及鉴定

构建HBV C基因型YIDD拉米夫定耐药株的全基因真核表达载体,为进一步深入探讨乙型肝炎病毒拉米夫定耐药的分子机制,寻求耐药后的有效治疗奠定基础。以重组质粒PMD18T-HBV-C为模板,采用PCR扩增HBV C基因型YIDD变异株的全基因组DNA,并将其定向克隆于真核表达载体PcDNA3.1( )中。获得的真核表达重组质粒PcDNA3.1( )-HBV-C(YIDD)通过酶切后电泳及测序进行鉴定。琼脂糖电泳结果证实PCR产物大小约为3.2 kb,与预期相同。酶切及测序结果证实,HBV C基因型YIDD拉米夫定耐药株全基因真核表达载体PcDNA3.1( )-HBV-C(YIDD)构建成功。     

珠芽魔芋的组织培养与快速繁殖

1植物名称珠芽魔芋[Amorphophallus bulbifer (Roxb.)Blume]。2材料类别芽鞘。3培养条件(1)愈伤组织诱导培养基:MS 6-BA 0.6mg·L~(-1)(单位下同) NAA 0.1;(2)不定芽诱导和增殖培养基:MS 6-BA 1.0 NAA 0.4:(3)生根培养基:1/2MS NAA 0.1。以上培养基均加入3%蔗糖和0.6%琼脂,pH 6.0。培养温度(25±2)℃。     

Characterization of a corrinoid protein involved in the C1 metabolism of strict anaerobic bacterium Moorella thermoacetica

The strict anaerobic, thermophilic bacterium Moorella thermoacetica metabolizes C1 compounds for example CO(2)/H(2), CO, formate, and methanol into acetate via the Wood/Ljungdahl pathway. Some of the key steps in this pathway include the metabolism of the C1 compounds into the methyl group of methylenetetrahydrofolate (MTHF) and the transfer of the methyl group from MTHF to the methyl group of acetyl-CoA catalyzed by methyltransferase, corrinoid protein and CO dehydrogenase/acetyl CoA synthase. Recently, we reported the crystallization of a 25 kDa methanol-induced corrinoid protein from M. thermoacetica (Zhou et al., Acta Crystallogr F 2005; 61:537-540). In this study we analyzed the crystal structure of the 25 kDa protein and provide genetic and biochemical evidences supporting its role in the methanol metabolism of M. thermoacetia. The 25 kDa protein was encoded by orf1948 of contig 303 in the M. thermoacetica genome. It resembles similarity to MtaC the corrinoid protein of the methanol:CoM methyltransferase system of methane producing archaea. The latter enzyme system also contains two additional enzymes MtaA and MtaB. Homologs of MtaA and MtaB were found to be encoded by orf2632 of contig 303 and orf1949 of contig 309, respectively, in the M. thermoacetica genome. The orf1948 and orf1949 were co-transcribed from a single polycistronic operon. Metal analysis and spectroscopic data confirmed the presence of cobalt and the corrinoid in the purified 25 kDa protein. High resolution X-ray crystal structure of the purified 25 kDa protein revealed corrinoid as methylcobalamin with the imidazole of histidine as the alpha-axial ligand replacing benziimidazole, suggesting base-off configuration for the corrinoid. Methanol significantly activated the expression of the 25 kDa protein. Cyanide and nitrate inhibited methanol metabolism and suppressed the level of the 25 kDa protein. The results suggest a role of the 25 kDa protein in the methanol metabolism of M. thermoacetica.     

岑溪药用野生稻高效内生固氮菌分离及促生特性

【目的】以广西岑溪市野生稻保护区的药用野生稻为材料,分离纯化内生细菌,筛选固氮酶活性较高和对作物促生效果较好的菌株。【方法】利用乙炔还原法检测固氮酶活性,采用SDS-PAGE全细胞蛋白电泳和IS-PCR指纹图谱技术对分离到的固氮菌进行聚类。利用16S rRNA基因和nifH基因确定其系统发育地位。采用钼锑抗比色法、Salkowski比色法和CAS检测法分别测定菌株溶磷性、生长素的分泌能力和产铁载体能力。通过平板和盆栽试验检测其对水稻的促生作用。【结果】共分离得到35株内生固氮菌,分为6个类群。其中CX24固氮酶活性最高,经鉴定属于Klebsiella variicola,其固氮酶活性为298.64 μmol/(L·h),为参比模式菌株DSM15968的9倍。另外该菌株还具有较高的溶磷性、分泌生长素和产铁载体能力,能够有效地促进水稻的萌发和生长。【结论】菌株CX24属于Klebsiella variicola,是一株高效内生固氮菌,具有很好的生产应用前景。