荷叶铁线蕨自然居群的遗传多样性研究

荷叶铁线蕨(Adiantumreniformevar. sinense)为我国特有植物,具有重要的经济价值,目前仅分布于重庆的少数地区。近几十年来,由于过度开发,该种的分布范围日益缩小,已处于灭绝的边缘。本研究利用等位酶标记检测了荷叶铁线蕨 6个自然居群共 136个个体的遗传多样性,共检测到了 5个酶系统的 14个位点,获得了 7个多态位点。结果表明:与其他蕨类植物相比,荷叶铁线蕨居群内的遗传多样性水平比较低。平均每位点的有效等位基因数(Ae)为 1. 778,多态位点百分率(P)为 0. 441,期望杂合度(He)为 0. 199,观察杂合度 (Ho)为 0. 235。其居群间的遗传分化也很低,居群间的遗传变异仅占总变异的 1. 49%,而 98. 51%的变异存在于居群内部。采用Hardy Wein berg平衡和固定指数F对荷叶铁线蕨的居群遗传结构进行了分析,结果表明其种群可能是以配子体间异交为主的混合交配体系。导致荷叶铁线蕨濒危的主要原因是生境的破坏以及过度开采所导致的生境片断化使其居群变小、近交率加大、遗传变异趋低,降低了其生存以及进化的潜力。     

Superoxide anion burst and taxol production induced by Ce in suspension cultures of Taxus cuspidata

Generation of reactive oxygen species (ROS) induced by Ce⁴⁺ in suspension cultures of Taxus cuspidata was investigated. The burst of superoxide anions (O₂√⁻) occurred rapidly after the addition of Ce⁴⁺ and reached maximum at 4.3 h, while the total level of the cellular reactive oxygen species maintained unchanged. The intracellular superoxide dismutase (SOD) and catalase (CAT) were activated while the intra/extracellular peroxidases (PODs) were inhibited accompanying the O₂√⁻ burst. The pretreatment of the suspension cultures with diphenylene iodonium (DPI), a suicide inhibitor of the NADPH oxidase, blocked the O₂√⁻ burst, inhibiting the cell apoptosis and taxol production induced by Ce⁴⁺. These results show that NADPH oxidase played a key role in O₂√⁻ burst and O₂√⁻ served as a mediator of Ce⁴⁺ for cell apoptosis and taxol production. The pretreatments of the suspension cultures with anthracene-9-carboxylate, an ion-channel blocker, nifedipine, a Ca²⁺-channel blocker, neomycin, a phospholipase C (PLC) inhibitor, or suramin, a G-protein inhibitor, decreased O₂√⁻ burst induced by Ce⁴⁺. It is thus inferred that Ce⁴⁺-induced O₂√⁻ burst, which mediated cell apoptosis and taxol production by activating the ion-channels, PLC, G-proteins and NADPH oxidase.     

Seasonal occurrence of helminths in the anadromous fish Coilia nasus (Engraulidae): parasite indicators of fish migratory movements

To understand the seasonal migration of the anadromous Coilia nasus , we attempted to identify the parasites infecting C. nasus and determine their seasonal occurrence. From June 2007 to July 2008, a survey of 775 C. nasus individuals from the estuary of the Yangtze River and the coast of the East China Sea revealed more than 7,300 parasites associated with the gills and alimentary tracts of C. nasus . The following 6 helminth taxa were identified, i.e., the monogeneans Heteromazocraes lingmueni and Helciferus tenuis, the digenean Elytrophallus coiliae, the acanthocephalan Acanthosentis cheni , and larvae of the nematodes Anisakis simplex and Contracaecum sp., all of which are marine or brackish-water parasites. The absence of freshwater helminths suggested that the parasites acquired in freshwater may have been accidentally, and easily, lost by the time the fish had reached the estuary and coast. Contrary to seasonal occurrence of the parasites' life cycles, the lowest mean abundance and prevalence of H. lingmueni and A. cheni occurred in August, which suggested the immigration of C. nasus from freshwater to the Yangtze estuary, with lower parasite burdens. The highest mean abundance and prevalence of the nematodes A. simplex and Contracaecum sp. in May and June, and the lowest in August, indicated the arrival of the fish from the coast and the Yangtze River, to the estuary, respectively. These findings suggested that a majority of the fish prepared for spawning migration in the estuary in spring and early summer and returned to the estuary after spawning in the lower and middle reaches of the Yangtze River in late summer.     

基于MuSIASEM理论的大连经济技术开发区可持续发展评价

基于社会生态系统代谢多尺度综合评估（MuSIASEM）理论,对2000-2007年大连经济技术开发区人类活动时间、体外能投入量和增加值进行综合评价.结果表明：2000-2007年,大连开发区居民生活水平逐年提高;农业逐渐萎缩;第二产业仍为区域支柱产业,能耗较大;第三产业发展落后于第二产业;区域整体和各个产业的体外能代谢率明显提高,能源密度不断下降;人类活动时间与体外能投入量不断减少的情况下,经济增加值稳步增长,区域整体发展呈可持续态势.     

The intrinsic mechanisms underlying the maturation of programming sequential spikes at cerebellar Purkinje cells

Cerebellum is involved in the motion coordination and working memory, to which the programming of sequential spikes at Purkinje cells is essential. It is not clear about the intrinsic mechanisms underlying spike capacity and timing precision as well as their postnatal maturation. We investigated the programming and intrinsic property of sequential spikes at Purkinje neurons during postnatal development by whole-cell recording in cerebellar slices. Cerebellar Purkinje neurons demonstrate the increasing of spike capacity and timing precision, as well as the lowering of refractory periods and threshold potentials during the postnatal maturation. In addition, the correlation between spike parameters and intrinsic properties converts to be more linear. This postnatal plasticity of neuronal intrinsic properties improves the timing precision and capacity of spike programming at cerebellar Purkinje neurons.     

Acidic microenvironment enhances MT1-MMP-mediated cancer cell motility through integrin β1/cofilin/F-actin axis

Tumor acidic microenvironment is the main feature of many solid tumors.As a part of the tumor microenvironment,it has a profound impact on the occurrence and de...     

Nitrate increases cisplatin chemosensitivity of oral squamous cell carcinoma via REDD1/AKT signaling pathway

Although cisplatin is one of the chemotherapeutics most frequently used in oral squamous cell carcinoma (OSCC) treatment,it exerts multiple side effects and poo...