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摘要： When they were first discovered, the wiggly grooves on slabs of ancientsandstone from central India were dramatic enough: They appeared to some to be 1.1-billion-year-oldworm tracks. That date would push the earliest known record of complex animals back a startlinghalf-billion years (Science, 2 October 1998, p. 19). But, it turns out, the first publication on thefind was greatly understated. Two groups report in the February issue of Geology that the rockmarked by the putative tracks is a whopping 1.6 billion years old. That predates the earliestgenerally accepted trace fossil of a complex animal--dated at 575 million years ago--by about abillion years. To some researchers, such a long gap strains credulity. Instead of traces of life,they are now seeing meaningless doodlings in ancient, squishy muds. The new, solid age for theIndian grooves comes from radiometric dating by two independent groups. They measured the clocklikerate of radioactive decay of uranium to lead in tiny crystals of zircon deposited with volcanic ashjust before and just after the grooves formed. Both groups--one led by paleontologist BirgerRasmussen of the University of Western Australia in Crawley, the other by geochemist JyotiranjanRay, now at the University of Hawaii, Manoa--got ages of just over 1.600 billion years, give or takeless than 0.008 billion years.

关键词： L1210   克隆细胞   生物学特性   肿瘤   动物模型   淋巴细胞白血病  

摘要： 目的　对L12 10细胞及其 4株克隆细胞建立的肿瘤动物模型的某些生物学特性进行比较研究 ,从中筛选出基本符合L12 10细胞生物学特性且一致性更好的克隆细胞。方法　北京肿瘤所L12 10细胞和 4株克隆细胞腹腔接种DBA 2小鼠 ,观察产生腹水的性质、腹水瘤细胞浓度和致小鼠死亡时间 ;皮下接种DBA 2小鼠 ,观察瘤块的生长情况 ;腹腔注射化疗药物环磷酰胺 (CY) ,比较对CY治疗的敏感性。结果　腹腔接种DBA 2小鼠均能生长腹水 ,其中克隆细胞L2H8、L3B12产生血性腹水 ,L3F9的腹水微血性 ,L3E11与肿瘤所L12 10细胞为无血性腹水 ;腹水瘤细胞的浓度及小鼠生存时间亦有差别。肿瘤所L12 10细胞及克隆细胞L3F9、L2H8、L3E11、L3B12第 10天瘤重依次为 1 9± 0 4 6、1 5± 0 3 8、0 75± 0 5 2、2 6± 0 3 0、2 0± 0 3 3g ;用CY治疗的抑瘤率分别是 4 8 7% ,81 3 % ,86 0 % ,78 7%及 67 1%。结论　 4株克隆细胞的生物学特性基本符合L12 10细胞 ,对化疗药物CY的敏感性均高于L12

关键词： 猫头鹰叫   探析   生物学特性   动物生物学   原因分析   猫头鹰属   形态结构特征   课外兴趣小组   九年义务教育   心理因素  

关键词： 分子生物学技术   动物营养   基因表达调控   应用   发展前景  

摘要： 分子生物学理论与技术的发展和应用已渗透到生命科学的各各领域,动物营养学的发展需要在分子水平上分析及解释营养素对动物机体的生理、病理变化调控,如生长发育、新陈代谢、遗传变异、免疫与疾病等。本文综述了分子生物学在动物营养学中的应用:利用分子生物学技术改造或生产动物性营养物质;从基因水平上研究如何提高动物生产性能及肉用性能:如肉质与瘦肉率等;在分子水平上研究营养与基因表达、调控的关系,以从根本上阐明营养对机体的作用机制;利用基因工程技术开发饲料资源。

关键词： review   Hediste diversicolor   biology   ecology   population dynamics   potential use  

摘要： The common ragworm Hediste diversicolor inhabits the shallow marine and brackish waters in the North Temperate Zone of the Atlantic. This infaunal species builds U or Y-shaped burrows in the soft sediments. H. diversicolor is gonochoristic and remains atokous throughout its life. Due to the facility of harvesting of individuals by hand and their maintenance, this species represents a good biological material for experimental studies. In consequence, the common ragworm served as a model for endocrine control of reproduction in Polychaeta and played a fundamental role in the study of immune defence in Polychaeta. Life history characteristics (longevity, spawning season, feeding tactics and growth) and population dynamics (sex ratio, density and biomass) vary greatly according to geographical location of the populations. In addition, inter-population morphological, biochemical and physiological differences have been noticed in individuals from different areas and different environmental conditions in the same areas and could be related to the limited dispersal capacity of the species. H. diversicolor interacts with its environment. The construction of burrows by individuals increases the sediment-water interface. When they ventilate their burrows, individuals verticalize oxic zones into the sediment and promote microbial and meiofaunal growth alongside their burrows. Moreover, the common ragworm is a species of commercial interest because of its use as bait in recreational fishing and as food in aquaculture. In order to alleviate environmental pressure caused by excessive demand over optimal sustainable yield of bait fisheries, intensive aquaculture has been proposed. The common ragworm could be also used as biomonitor of pollution in estuarine ecosystems.

关键词： 病理生理   实验生理学   性学会   动物生物学   功能形态学   相关学科   理学会  

摘要： 第4届国际病理生理大会定于2002-06-29/07-05在匈牙利首府布达佩斯召开,此次会议由匈牙利生理学会、匈牙利医学会和布达佩斯会议中心联合举办。匈牙利生理学会(HPS)是国际病理生理学会(ISP)的一员,该会历史悠久为综合性、多学科(包括人体及动物生物学、病理生理学、临床生理学、比较生理学、实验生理学和功能形态学等)的传统性学会组织。本次大会主席生理学教授Emil Monos(***)和该会秘书长病理生理学教授Lajos ***(***)以及匈牙利生理学会、匈牙利医学会和布达佩斯热忱欢迎世界各地的病理生理学及其他相关学科的学者们前往。

关键词： 鉴别   检测   牛源性成分   羊源性成分   聚合酶链反应   动物源性饲料   牛   海绵状脑病   绵羊   痒病   检疫  

摘要： 为了防止海绵状脑病疫区和痒病疫区反刍动物源性饲料进入我国 ,非常有必要对贸易往来中的肉骨粉品种来源进行鉴定检测。我们采用分子生物学方法从动物源性饲料中鉴别检测牛、羊特异性线粒体DNA的片段 ,并用限制性内切酶SspⅠ对PCR产物进行酶切鉴定及DNA序列测定。该方法的灵敏度可达 0 .12 5 % ,具有灵敏度高、快速和特异性强的优点。

关键词： life history   Developmental Biology   Biologists   Life History Traits   Echinodermata   evolution  

摘要： Evolutionary biologists studying life history variation have used echinoderms in experimental, laboratory, and field studies of life history evolution. This focus on echinoderms grew originally from the tradition of comparative embryology, in which echinoderms were central. The tools for obtaining and manipulating echinoderm gametes and larvae were taken directly from comparative embryological research. In addition, the comparative embryologists employed a diverse array of echinoderms, not a few model species, and this diversity has led to a broad understanding of the development, function, and evolution of echinoderm larvae. As a result, this branch of life history evolution has deep roots in comparative developmental biology of echinoderms. Here two main aspects of this relationship are reviewed. The first is a broad range of studies of fertilization biology, dispersal, population genetics, functional morphology, and asexual reproduction in which developmental biologists might take a keen interest because of the historical origins of this research in echinoderm comparative embryology. The second is a similarly broad variety of topics in life history research in which evolutionary biologists require techniques or data from developmental biology in order to make progress on understanding patterns of life history variation among echinoderm species and higher taxa. Both sets of topics provide opportunities for interaction and collaboration.

关键词： Sphaeroma wadai   isopod   reproductive biology   stone boring   size-assortative mating   parental care  

摘要： Population structure, growth and reproductive activities were investigated in a field population of an intertidal isopod, Sphaeroma wadai, burrowing in sandstone for 1 year. The sex ratio was biased toward females throughout the year (male/female: 31.9-79.7%). Heterosexual pairs living in the same burrow occurred from November to July, and their sizes were positively correlated to each other only in the main pairing season. Ovigerous females were observed from April to September, with the brood size ranging from 1 to 37 (18.8, SD 9.35). The number of broods per female is estimated to be one per year. The earliest stage of juveniles occurred from June to September, with most of them cohabiting with mature females in the same burrow. With successive developmental stages of juveniles, the proportion of juveniles cohabiting with mature females decreased. The maximum body length was greater in females (10.70 mm) than in males (10.20 mm). The life span was estimated at almost 2 years or about 15 months. We conclude that the distinct life history characters of S. wadai (sexual dimorphism, prolonged mate-guarding, cohabiting of females and offspring) are a consequence of its boring habit.