蓖麻蚕18S rRNA基因3′末端的顺序特征

本文测定了蓖麻蚕18S rRNA基因(rDNA) 3′末端及其外侧的DNA顺序。将这一顺序与家蚕、果蝇、大鼠 18S rDNA 3′末端顺序以及大肠杆菌16 S rDNA 3′末端顺序作了比较,发现它们间有惊人的同源性。不仅如此,这些基因的3′末端所形成的茎环结构也十分相似,在3′末端还有保守的EcoRI切点。这些研究结果对了解18S rRNA 3′末端在蛋白质合成中的功能及在rRNA前体加工成熟中的作用;对于了解rRNA基因的进化打下了基础。     

Karyotypic characterization and genomic organization of the 5S rDNA in <Emphasis Type="Italic">Erpetoichthys calabaricus</Emphasis> (Osteichthyes,Polypteridae)

Polypterids are a group of Osteichthyan fish whose evolutionary relationships with closer basal ray-finned and lobe-finned fish have been disputed since their discovery. Very little is known about the evolutive karyology in the whole Polypteriformes group. In order to fill this gap, a cytogenetic analysis of Erpetoichthys calabaricus species was performed, using both classical and molecular techniques. Karyotype structure (2n = 36; FN = 72), chromosome location of telomeric sequences (TTAGGG)n and ribosomal 5S and 18S rRNA genes were examined in twenty specimens of E. calabaricus by using Ag-NOR, classical C-banding, sequential CMA3/4',6-diaminidino-2-phenylindole (DAPI) staining and fluorescent in situ hybridization (FISH). CMA3 marked all centromerical and some (no. 1 and no. 15) telomeric regions. Staining with Ag-NOR and CMA3 showed the presence of two NORs on the p arm of the chromosome pair no. 1. Hybridization with telomeric probes (TTAGGG)n showed signals at the end of all chromosomes. 5S rDNA was cloned and sequenced. After the alignment, the 5S rRNA sequences revealed an organization made up of two different classes of tandem arrays (type I and type II). FISH with 5S rDNA marked the telomeric regions of the small chromosome pair no. 15, while FISH with 18S rDNA marked the telomeric region of the pair no. 1. The results obtained were compared with cariological data on closer species now available in literature.     

仔猪BPI基因表达水平与大肠杆菌F18菌株感染的关系

文章利用已建立的苏太猪F18大肠杆菌病抗性和敏感性资源家系群体作为实验材料,分别选择8头35日龄左右生长性状基本一致的大肠杆菌F18菌株抗性和敏感性断奶仔猪,运用Real-time PCR方法检测BPI基因mRNA在断奶仔猪各个组织的分布情况,并比较其在大肠杆菌F18菌株抗性型和敏感型断奶仔猪个体间的差异表达水平,为探讨该基因在免疫和抗大肠杆菌F18菌株感染中的作用提供依据。结果表明,在对所有个体检测的11个组织中,BPI基因在心、肝、脾、肺、肾、胃、肌肉、胸腺、淋巴结中几乎不表达,或表达量很低,但在十二指肠和空肠中表达量很高。在十二指肠和空肠中,BPI基因在抗性组的表达量均显著高于敏感组的表达量(P<0.05)。由此表明,BPI基因对抗断奶仔猪肠道中大肠杆菌F18菌株的感染可能具有直接作用,并且个体对大肠杆菌F18菌株的抗性可能与BPI基因在肠道中表达量上调有关。     

人白细胞介素18半胱氨酸的定点突变及其对活性的影响

为研究IL 18结构与功能的关系 ,用重叠延伸PCR定点突变技术构建人白细胞介素 18(hIL 18) 4个半胱氨酸的突变体hIL 18C74 S、C10 4 S、C112 S和C163 S。将突变体的cDNA与原核细胞表达载体pJW2重组并转化大肠杆菌JM10 1。经热诱导后 ,4个突变体在大肠杆菌中均得到了高效表达。表达的蛋白质主要以包涵体的形式存在。包涵体经超声破碎 ,2mol/L尿素洗涤 ,8mol/L尿素溶解 ,SephadexG 10 0柱纯化后 ,纯度可达 90 %以上。以诱导人外周血单个核细胞 (PBMC)产生IFN γ的能力为指标检测复性突变体的活性。结果显示除C10 4 S外 ,其他 3个突变体的生物活性均低于野生型hIL 18,C74 S、C112 S和C163 S的活性分别是野生型hIL 18活性的 5 %、5 8%和11%。证明Cys74 、Cys163 为hIL 18诱导产生IFN γ的功能所必需     

关于石油母质来源的探讨

浮游微藻是海洋和湖泊中的初级生产力,生物量巨大,平均脂类含量高,是沉积岩中有机质的主要母质来源,对石油和天然气的形成贡献最大。对下辽河坳陷早第三纪的大量微体浮游藻类化石研究表明,该坳陷油气资源的形成和微体浮游藻类,特别是沟鞭藻的大量存在密切相关,浮游藻类是该坳陷盆地油气形成有机质来源的重要基础之一。在微藻热模拟成烃实验中引入成岩早期生物、地化因子的影响,使模拟实验更接近自然界的实际情况。对微藻来源的生物标志物研究表明,作为高盐环境重要标志物的2,6,10,14,18—五甲基二十烷也可能来源于藻类生物。在藻类热模拟产物中发现惹烯的存在,提示在解释油气藏的生物母质来源时必须特别谨慎。     

A New Freshwater Naked Lobose Amoeba Korotnevella venosa n. sp. (Amoebozoa,Discosea)

A new freshwater species of naked lobose amoebae Korotnevella venosa n. sp. isolated from freshwater pond in St. Petersburg, Russia was studied with light and transmission electron microscopy. Basket scales of this species have six vertical columns supporting perforated rim. The latter has tongue‐like broadening with membranous region. Vertical columns bifurcate at both ends so that neighboring columns are connected by their bifurcations forming combined structure. Basket scales of K. venosa are similar to those of Korotnevella hemistylolepis in having six full‐length vertical columns and perforated rim. At the same time, they are different in having tongue‐like broadening of perforated rim with membranous region and absence of six half‐length columns and an intermediate crosspiece. Phylogenetic trees based on 18S rDNA gene placed K. venosa either at the base of the whole Korotnevella clade, next to K. hemistylolepis, or as a sister to the clade comprising Korotnevella species with latticework basket in large scales.     

Pleistocene paleoenvironmental evolution at continental middle latitude inferred from carbon and oxygen stable isotope analysis of ostracodes from the Guadix-Baza Basin (Granada, SE Spain)

A representative paleoenvironmental reconstruction of continental middle latitude from ca. 2 my to the upper part of Middle Pleistocene (279 ± 77 ky) was obtained from the carbon and oxygen stable isotopes analyzed in ostracode shells (Cyprideis torosa) recovered in the Guadix-Baza Basin (SE Spain), an intramontaneous closed depression filled by alluvial and lacustrine sediments. This study was performed along a 356-m-thick composite section, dated previously by paleomagnetism and the amino acid racemization method. δ¹³C and δ¹⁸O profiles reflected changes in temperature, the evaporation/infill ratio in the water bodies and the amount of rain. δ¹³C is also affected by changes in plant biomass: periods with high δ¹³C and δ¹⁸O values are associated with warm and dry regimes, and with less vegetation, which, in some cases, coincide with the development of displacive gypsum crystals, whereas low δ¹³C and δ¹⁸O values correlate with cold and humid episodes, which cause more vegetation biomass and, therefore, increasing the input of isotopically light carbon. Intermediate δ¹⁸O values are linked to temperate dry or humid episodes when they coincide with high or low δ¹³C values, respectively. 86 paleoclimatic events were distinguished in the Pleistocene record from the δ¹³C and δ¹⁸O profiles. From both the statistical analysis of the geochemical data and the geological observations, four Cold and Humid Long Periods (low δ¹⁸O) and four Warm and Dry Long Periods (high δ¹⁸O) were defined. This differs with respect to the paleoclimatological behavior established for the Northern Hemisphere where during cold periods (glacial), no water was available while permafrost conditions persisted, whereas in warm episodes (interglacial), higher precipitation rates occurred. Good correspondences between the Guadix-Baza Basin paleoclimatic record and a marine oxygen-isotope sequence, two continental cores and other long Mediterranean paleoenvironmental records (pollen sequences from Israel) were found, which suggested that climate changes in the Guadix-Baza Basin were in tune with global climatic changes.     

1株海洋真菌ZH2.1的鉴定及生物学特性初步研究

从南海海域白姑鱼消化道分离到1株海洋真菌ZH2.1,对其进行了系统鉴定和生物学研究。采用传统的形态学鉴定方法,并结合18S rDNA序列分析确定其归属。18S rDNA序列分析表明其与孔状短小茎点霉Phoma exigua var.exigua在进化位置上最为接近,其18S rDNA在GenBank的登录号为FJ450059。结合形态学观察结果,可认为菌株ZH2.1为茎点霉属真菌。对该菌株的部分生物学特性研究表明,ZH2.1为兼性海洋真菌,最适生长盐度为3%。此外,在微氧条件下也可生长。     

不同日粮饲养黄牛的胃部微生物群落多样性比较分析

为分析不同饲料喂养对黄牛胃中微生物群落结构的影响,分别用芒草单一喂养和农家混合饲料喂养两年的黄牛为实验组和对照组。以瘤胃、蜂巢胃、重瓣胃和皱胃四个胃中的微生物为研究对象,采用原位包埋裂解法和脉冲场电泳（pulsed field gel electrophoresis,PFGE）提取微生物总 DNA,脉冲场电泳（pulsed field gel elec-trophoresis,PFGE）。使用细菌16S rRNA 引物341F ／534R 及真菌18S rDNA 引物 NS1／GCFungi 进行降落 PCR 扩增。变性梯度凝胶电泳（denaturing gradient gel electrophoresis,DGGE）对扩增产物进行区分,使用硝酸银染色。电泳扫描结果通过 Quantity one 软件进行分析,SPSS 软件进行数据统计。针对实验组和对照组瘤胃样品共性条带和特性条带测序并比对。结果表明：实验组与对照组细菌群落结构变化较大,UPGAM聚类图上被分为两支,相似性只有0．35。且香农多样性指数及条带丰度都明显少于对照组。真菌 DGGE 图谱条带差别不大,聚类图上显示实验组四个样品与对照组四个样品相似性在0．43～0．68之间。多样性及条带丰度在实验组与对照组之间差异0．0027～0．5999。测序结果,细菌与数据库中未培养细菌种类较为接近,而真菌中部分与已知菌种接近。芒草单一饲养对牛胃中的微生物群落结构具有极大的影响,对细菌的影响尤为明显。