一个由HSVⅠ诱导的类SR蛋白新基因的克隆

 根据mRNA差异显示分析 ,由单纯疱疹病毒 (HSV)Ⅰ型结合人成纤维细胞膜受体后 2h诱导产生的早期基因cDNA库中 ,分离到一个编码具有SR蛋白结构特征的新基因 ,该基因长 90 4bp .编码产生的蛋白含 12 1个氨基酸残基 ,分子量 14 9kD ,具有RS重复区和PPLP结构域 ,但不具备SR蛋白家族所特有的RNA识别区域 (RRM) .主要分布于细胞质内 ,仅在细胞膜相应受体与HSVⅠ结合后特异产生     

西藏晚白垩世晚Campanian期至早Maastrichtian期菊石群——中国最年轻的菊石群

记述产自西藏南部仲巴县的一个中国目前所知最年轻的菊石群 ,含 2科 4属 6种 ,其中 4新种。据菊石群面貌和它们所产出的层位可以划分出上、下两个组合带 :上部Pachydiscuscf.hidakaensis Libycoceraszhongbaense组合带 ;下部Manambolitescujiangdingensis M .pivaeteaui组合带。产菊石的曲贝亚组的下段和上段的中、下部(82F5 0及其以下层位 )为晚Campanian期 ,上段上部 (即 82F5 2及其以上层位 )为早Maastrichtian期。     

Effects of temperature on developmental performance, survival and growth of sea lamprey embryos

This study assesses the influence of thermal regime on the development, survival rates and early growth of embryos of sea lamprey Petromyzon marinus incubated at five constant temperatures (7, 11, 15, 19 and 23° C). The time from fertilization to 50% hatching and from hatching to 50% burrowing were inversely related to incubation temperature. All the embryos incubated at 7° C died at very early stages, while those maintained at 11° C did not attain the burrowing stage. Survival from fertilization to hatching was 61, 89, 91 and 89% at 11, 15, 19 and 23° C, decreasing to 58, 70 and 70% from hatching to burrowing at 15, 19 and 23° C, respectively. Larvae reared during the first 3 months of exogenous feeding in a common environment at constant 21° C, revealed maximum survival for an incubation temperature of 15° C (43% of burrowed larvae) decreasing strongly at 19° C (16%) and 23° C (one suvivor among 240 larvae). Body length at the burrowing stage was maximum for embryos incubated at 19° C, but body mass increased in the interval 15–23° C. Mean incubation temperatures experienced by 117 broods during the embryonic development in the source river were estimated in 15·3±2·30° C and 16·7±1·76° C (mean±1 s.d .) for the periods fertilization-to-hatching and hatching-to burrowing, respectively.     

Late Quaternary environmental changes in the Lagoa da Curuça region (eastern Amazonia, Brazil) and evidence of Podocarpus in the Amazon lowland

Late-glacial and Holocene vegetational and climate dynamics and human impact of the eastern Amazon rain forest in the coastal region of eastern Pará State in northern Brazil have been studied in two sedimentary recores from Lagoa da Curu?a. Seven radiocarbon dates provide the chronology for two pollen and charcoal records starting from 11,700 and 9440 uncal B. P. to present. Dense and high diverse terra firme Amazon rain forest in the coastal area shows that there was no savanna during the Late-glacial period. The occurrence of Podocarpus trees in the coastal region during the Late-glacial indicate wet and markedly colder conditions at that time. A possible habitat for Pleistocene populations of Podocarpus trees which are now also evident from several other Amazon regions is discussed. There were no rain forest fires between 11,700 and 10,840 uncal B. P. The increase of charcoal particles in the lake deposits after this period suggest an early Amerindian occupation of the coastal region. Received March 26, 2001 / Accepted August 8, 2001     

Female and male contribution to egg size in salmonids

Egg size contributes to other life history traits of an individual. It is traditionally considered as a maternally determined characteristic to which the male does not have any direct contribution. However, a recent finding in insects suggests that males can affect egg size also directly. In fish, the male effect could take place only during egg swelling, as the final egg size is reached after that. We studied egg size in four freshwater salmonid species (the land-locked Atlantic salmon, the brown trout, the Arctic charr and the lake trout) right after fertilisation (initial egg size) and after the swelling phase (final egg size). The results showed that the final egg size is affected not only by the initial egg size but also by both the female and the male through the process of egg swelling. This study suggests that paternal contribution may form a previously largely ignored source of variation in early life history traits in salmonid fish.     

Different Functional and Structural Properties of Lactate Dehydrogenase Isozymes at Different Stages of Danio rerioOntogenesis

We studied properties of lactate dehydrogenase isozymes expressed at different stages of Danio rerioontogenesis. H₄-LDH and a minor fraction H₃M₁are expressed during embryonic development. The muscle isozyme (₄) appears after the beginning of muscle contractions in the embryo. ₄and ₄isozymes isolated from the heart and skeletal muscle of the adult fish, respectively, show significant differences in terms of Michaelis constant (K _m) activation energy (AE), and inactivation temperature. H₄-LDH isozymes isolated from unfertilized eggs, the skeletal muscle of larvae, and the heart of the adult fish differ inK _mand activation energy, as well as in inactivation temperature. We propose that these differences may be associated with a ligand interacting with the H₄isozyme at different steps of ontogenesis.     

Synthesis degradation, and subcellular localization of synaptotagmin IV, a neuronal immediate early gene product

Synaptotagmin IV (Syt IV) is an immediate early gene induced by depolarization in rat PC12 cells and in rat hippocampus. We prepared an antiserum to Syt IV protein. The 46-kDa Syt IV protein is nearly undetectable by western blotting in unstimulated PC12 cells. After depolarization, Syt IV increases rapidly, peaks at 4 h, and decays to near baseline levels by 12 h. Forskolin stimulation also leads to rapid Syt IV protein accumulation. The rate of Syt IV protein synthesis, determined by labeling with radioactive amino acids and immunoprecipitation, is low in unstimulated PC12 cells, but increases over the first 3 h after forskolin stimulation and remains elevated for several hours. Syt IV protein is relatively labile; metabolically labeled Syt IV has a half-life of approximately 2 h in PC12 cells. Sucrose density gradient fractionation and vesicle immunoisolation experiments suggest that Syt IV protein is present in both synaptic-like microvesicles and secretory granules. Vesicles immunoisolated from forskolin-treated PC12 cells with anti-Syt I antibody contain radioactively labeled Syt IV, demonstrating that Syt I and Syt IV colocalize in common vesicles. These results suggest that Syt IV protein, after its stimulation-induced synthesis, is rapidly transported to secretory vesicles where it may transiently modulate the exocytotic machinery.     

RGS mRNA expression in rat striatum: modulation by dopamine receptors and effects of repeated amphetamine administration

Single injections of cocaine, amphetamine, or methamphetamine increased RGS2 mRNA levels in rat striatum by two- to fourfold. The D1 dopamine receptor-selective antagonist SCH-23390 had no effect by itself but strongly attenuated RGS2 mRNA induction by amphetamine. In contrast, the D2 receptor-selective antagonist raclopride induced RGS2 mRNA when administered alone and greatly enhanced stimulation by amphetamine. To examine the effects of repeated amphetamine on RGS2 expression, rats were treated with escalating doses of amphetamine (1.0-7.5 mg/kg) for 4 days, followed by 8 days of multiple daily injections (7.5 mg/kg/2 h x four injections). Twenty hours after the last injection the animals were challenged with amphetamine (7.5 mg/kg) or vehicle and killed 1 h later. In drug-naive animals, acute amphetamine induced the expression of RGS2, 3, and 5 and the immediate early genes c-fos and zif/268. RGS4 mRNA levels were not affected. Prior repeated treatment with amphetamine strongly suppressed induction of immediate early genes and RGS5 to a challenge dose of amphetamine. In sharp contrast, prior exposure to amphetamine did not reduce the induction of RGS2 and RGS3 mRNAs to a challenge dose of amphetamine, indicating that control of these genes is resistant to amphetamine-induced tolerance. These data establish a role for dopamine receptors in the regulation of RGS2 expression and suggest that RGS2 and 3 might mediate some aspects of amphetamine-induced tolerance.