苏铁叶绿体的超微结构和功能及对CO2浓度倍增的响应

本研究首次揭示了七种苏铁类植物叶绿体的超微结构。即苏铁科(Cycadaceae)的攀枝花苏铁(C. panzhihuaensis).苏铁(C. revoluta)、叉叶苏铁(C.micholitzii)、 刺叶苏铁(C.rumphii和多歧苏铁(C.multipinnata)，蕨铁科(Stangeriaceae)的蕨铁(Stangeria eriopus)和泽米科(Zamiaceae)的米德尔堡大苏铁(Encephalortos middelburgensis).根据它们叶绿体内膜结构的不同将其大体分为两种类型：1、阴生型叶绿体：多歧苏铁和刺叶苏铁为此类型，它们的叶绿体类囊体垛叠程度高，基粒垛较宽，单个基粒中类囊体的数量很多，有的甚至上百;2、阳生型叶绿体：攀枝花苏铁、米德尔堡大苏铁、苏铁、蕨铁和刺叶苏铁以及外类群的凤尾蕨(Pteris vittata)的叶绿体均有阳生型叶绿体的特征：类囊体膜垛叠程度低，基粒较小。根据它们叶绿体的结构特征，又将其分为两组： ( 1)攀枝花苏铁，米德尔堡大苏铁和叉叶苏铁叶绿体中均有类囊体膜膨大的现象： (2)苏铁和蕨铁在苏铁类中是比较原始的种类，它们的叶绿体与在系统进化上较苏铁类低等的凤尾蕨的叶绿体中都有几个基粒聚集成簇的现象，说明苏铁类在进化的同时一些较原始的性状仍保留了下来。这些苏铁都在温室相同的条件下生长了两年多，但它们的叶绿体结构仍然能够反应原产地生境特点，说明在长期进化中，叶绿体对环境的适应方式已在基因水平上稳定下来，苏铁类植物不同叶绿体结构的形成有其遗传基础。 多歧苏铁，攀枝花苏铁，叉叶苏铁的叶绿体膜垛叠程度依次降低，与此相应，它们的chla/b和F730/F684依次升高，反应了结构与功能的一致性。 选用具有阳生型叶绿体的攀枝花苏铁和有阴生型叶绿体的多歧苏铁用不同的C02浓度（350 umol mol-l和700umol mol-l）处理后观察其叶绿体结构的变化，结果发现C02浓度倍增对它们的叶绿体影响甚微，而作为对照的无论��C3植物小麦(Triticum italica)还是C4植物谷子(Setaria italica)在C02倍增的条件下叶绿体内均有大量淀粉粒积累，并有膜结构改变。这说明苏铁的叶绿体结构有保守性，这有可能是苏铁类能历经亿万年的沧桑而生存下来的结构基础之一。

草鱼补��C3基因的克隆及在感染大中华鳋草鱼个体的表达分析

利用抑制差减杂交技术 ,构建了草鱼与大中华鳋感染相关的差减文库 ,测序得到一些免疫相关基因 ,其中包含与鲤补��C3高度同源的片段 .根据此片段设计引物 ,采用RACE(rapidamplificationofcDNAends)技术 ,克隆了草鱼补��C3的cDNA ,其全长5 171bp ,编码 16 77个氨基酸 .与已报道的补��C3一样 ,草鱼补��C3同样具有在功能上比较重要的残基以及保守的硫酯区 .草鱼补��C3与高等脊椎动物鸡、小鼠以及人��C3在氨基酸序列上有着相近的相同率 (37.9%～39.1%

Redescription of Difflugia tuberspinifera Hu, Shen, Gu et Gong, 1997 (Protozoa : Rhizopoda : Arcellinida : Difflugiidae) from China

The freshwater testate amoeba Difflugia tuberspinifera Hu et al. 1997 collected from pond and lake in China, is investigated by light and scanning electron microscopy. This little known taxon is redescribed and its morphology, biometry and ecology are supplied. After carefully comparison with other six similar species including Difflugia bartosi Stepanek, D. corona Wallich, D. corona cashi Deflandre, D. corona tuberculata Vucetich, D. muriformis Gauthier-Lievre et Thomas and Netzelia tuberculata (Wallich) Netzal we believe that the sub-spherical to spherical shell, the mulberry-shaped appearance, the 7-10 apertural tooth-like structures, the short collar and the conical spines numbering from 4 to 8 at the upper equatorial region in D. tuberspinifera set it apart from other species. Besides, statistical analysis indicates that D. tuberspinifera is a size-monomorphic species characterized by a main-size class and a small size range and the shell height is significant correlated with other morphometric characters at p < 0.05 excepting the number of aperture tooth-like structures and the number of spines. Moreover, D. tuberspinifera inhabits not only lotic but also lentic environment.

Rotifera recorded from China, 1893-1997, with remarks on their composition and distribution

A search of the literature on rotifers recorded from China, includes today 477 valid species names and 42 subspecies or infrasubspecific variants in 84 genera and 28 families recorded since 1893. Chinese rotifera research is reviewed, and all recorded species are listed with current taxonomic status and their first localities in China. Most of the named taxa are widely distributed or cosmopolitan, with only a small number (about 3%) possibly restricted to China. This fauna exhibits 15 endemic taxa. The composition and distribution of Chinese Rotifera are briefly analyzed. It is likely that considerably more rotifers remain to be described from China as further study to be carried on and taxonomic resolution improves.

Cluster assistant generation of C2+ and C3+ ions in nanosecond laser ionization of seeded benzene beam

Cluster assisted photoionization processes of benzene, which was seeded in argon, induced by an intense 25 ns Nd-YAG laser has been studied by means of time-of-flight mass spectrometry. At the laser intensity of 10(11) W/cm(2), multicharged ions Cq+ (q = 2-3) with kinetic energy up to 150 eV were observed in the mass spectra. Strong evidences Support that these ions are formed in the Coulomb explosion of multicharged benzene cluster ions. (C) 2004 Elsevier B.V. All rights reserved.

碳同位素技术��C3作物水分利用效率研究中的应用

碳同位素技术已在地学、环境学及植物学等领域得到广泛应用。本文综述了该技术在作物水分利用效率研究中的进展 ,并对其进行了评价 ,同时探讨了碳同位素分辨力 (Δ)的遗传学特征 ,以揭示Δ和水分利用效率的关系 ,为水分利用效率的研究提供新的方法和技术

Stable Carbon Isotopic Composition in Soil Organic Carbon and C3/C4 Source Variations at the Haibei Alpine Meadow

Stable carbon isotopes of organic matter originated from different soil layers (0～5 cm, 5～15 cm, 15～25 cm, 25～35 cm, 35～50 cm, 50～65 cm) were investigated in the Haibei Alpine Meadow Ecosystem Research Station of the Chinese Academy of Sciences. The preliminary results indicated that δ13C values of soil organic matter increased with increased soil depth. δ13C of soil organic carbon in 0～5 cm layer showed the lowest value, -25.09‰; while 50～65 cm soil layer possessed the lowerδ13C value, -13.87‰. Based on mass balance model of stable isotopes, it was proposed that the percentage of C4 carbon source tend to increase with increased soil depth. The preliminary study indicated that alpine meadow might have undergone a successive process from C4-dominated community to C3-dominated one. However, changing δ13C values in atmospheric CO2 overtime and different processes of soil organic carbon formation (or eluviation) might somewhat contribute to increasing δ13C values. In this case, mass balance model would underestimate C3 community and overestimate C4 community.

Stable carbon isotope analyses show dominance of C3 grasses in the feed selected by small herbivores at the alpine meadow at the Tibetan Plateau

Muscle samples were collected from small herbivorous mammals (Ochotona curzoniae, Microtus oecnomus, Myospalax fontanierii and Lepus oiostolus) at the alpine meadow ecosystem at the Tibetan Plateau in order to address variability in stable carbon isotope composition. Stable carbon isotope values of muscles remain steady and show no significant variations (-25.72 to -27.04 parts per thousand) among the four small mammal species. Based on the mass balance theory of stable isotopes, it is proposed that small herbivorous mammals mainly (or totally) rely on C3 grasses as food supply, and there is few or no distribution of C4 grasses at the ecosystem. The results reflect our previous study on the isotope patterns of plant species. Thus, stable carbon isotope analysis of muscles provides a method to address dietary selection and dietary variability in herbivores. In addition, stable carbon isotopic analyses can be used to address changes in vegetation distributions in ecosystem and paleovegetaion and paleoclimate.