中国西部退耕还林基本策略研究

21世纪,生态危机成为人类面临的最大威胁,森林作为陆地生态系统的主体,自然成为世人瞩目的集点.由于中国西部水土流失、土地沙化、水资源紧张、生物多样性锐减等问题越来越突出,给人民的生活与国民经济发展造成巨大损失.退耕还林成为中华民族生存与发展的根本大计,这不仅关系到当代人的生存与发展,而且关系到子孙后代的生存与发展.文章在上述背景下,提出了符合中国实际的对策,供决策部门参考.

Symmetrical 1-pyrrolidineacetamide showing anti-HIV activity through a new binding site on HIV-1 integrase

Aim: To characterize the functional and pharmacological features of a symmetrical 1-pyrrolidineacetamide, N,N'-(methylene-di-4,1-phenylene) bis-1-pyrrolidineacetamide, as a new anti-HIV compound which could competitively inhibit HIV-1 integrase (IN) bindi

Molecular cloning and expression characterization of ApoC-I in the orange-spotted grouper

Endogenous yolk nutrients are crucial for embryo and larval development in fish, but developmental behavior of the genes that control yolk utilization remains unknown. Apolipoproteins have been shown to play important roles in lipid transport and uptake through the circulation system. In this study, EcApoC-I, the first cloned ApoC-I in teleosts, has been screened from pituitary cDNA library of female orange-spotted grouper (Epinephelus coioides), and the deduced amino acid sequence shows 43.5% identity to one zebrafish (Danio rerio) hypothetical protein similar to ApoC-I, and 21.2%, 21.7%, 22.5%, 20%, and 22.5% identities to Apo C-I of human (Homo sapiens), house mouse (Mus musculus), common tree shrew (Tupaia glis), dog (Canis lupus familiaris) and hamadryas baboon (Papio hamadryas), respectively. Although the sequence identity is low, amphipathic alpha-helices with the potential to bind to lipid were predicted to exist in the EcApoC-I. RT-PCR analysis revealed that it was first transcribed in gastrula embryos and maintained a relatively stable expression level during the following embryogenesis. During embryonic and early larval development, a very high level of EcApoC-I expression was in the yolk syncytial layer, indicating that it plays a significant role in yolk degradation and transfers nutrition to the embryo and early larva. By the day 7 after hatching, EcApoC-I transcripts were observed in brain. In adult, EcApoC-I mRNA was detected abundantly in brain and gonad. In transitional gonads, the EcApoC-I expression is restricted to the germ cells. The data suggested that EcApoC-I might play an important role in brain and gonad morphogenesis and growth.

Classical two-site fidelity and quantum phase transitions in the Ising model and the extended Hubbard model

In this Letter, the classical two-site-ground-state fidelity (CTGF) is exploited to identify quantum phase transitions (QPTs) for the transverse field Ising model (TFIM) and the one-dimensional extended Hubbard model (EHM). Our results show that the CTGF exhibits an abrupt change around the regions of criticality and can be used to identify QPTs in spin and fermionic systems. The method is especially convenient when it is connected with the density-matrix renormalization group (DMRG) algorithm. (C) 2008 Elsevier B.V. All rights reserved.

Starch grains from dental calculus reveal ancient plant foodstuffs at Chenqimogou site, Gansu Province

National Natural Science Foundation of China [40771205]; National Science Fund for Distinguished Young Scholars [40625002]; Chinese Academy of Sciences [KZCX2-YW-315]

Changes in individual plant traits and biomass allocation in alpine meadow with elevation variation on the Qinghai-Tibetan Plateau

Plant traits and individual plant biomass allocation of 57 perennial herbaceous species, belonging to three common functional groups (forbs, grasses and sedges) at subalpine (3700 m ASL), alpine (4300 m ASL) and subnival (>= 5000 m ASL) sites were examined to test the hypothesis that at high altitudes, plants reduce the proportion of aboveground parts and allocate more biomass to belowground parts, especially storage organs, as altitude increases, so as to geminate and resist environmental stress. However, results indicate that some divergence in biomass allocation exists among organs. With increasing altitude, the mean fractions of total biomass allocated to aboveground parts decreased. The mean fractions of total biomass allocation to storage organs at the subalpine site (7%+/- 2% S.E.) were distinct from those at the alpine (23%+/- 6%) and subnival (21%+/- 6%) sites, while the proportions of green leaves at all altitudes remained almost constant. At 4300 m and 5000 m, the mean fractions of flower stems decreased by 45% and 41%, respectively, while fine roots increased by 86% and 102%, respectively. Specific leaf areas and leaf areas of forbs and grasses deceased with rising elevation, while sedges showed opposite trends. For all three functional groups, leaf area ratio and leaf area root mass ratio decreased, while fine root biomass increased at higher altitudes. Biomass allocation patterns of alpine plants were characterized by a reduction in aboveground reproductive organs and enlargement of fine roots, while the proportion of leaves remained stable. It was beneficial for high altitude plants to compensate carbon gain and nutrient uptake under low temperature and limited nutrients by stabilizing biomass investment to photosynthetic structures and increasing the absorption surface area of fine roots. In contrast to forbs and grasses that had high mycorrhizal infection, sedges had higher single leaf area and more root fraction, especially fine roots.

Further Indo-West Pacific palaemonoid shrimps (Crustacea : Decapoda : Palaemonoidea), principally from the New Caledonian region

Based on the material deposited in the Museum national d'Histoire naturelle, Paris, collected from the Indo-West Pacific, principally from the New Caledonian region, the present paper reports 117 palaemonoid shrimp species, which belong, respectively, to Anchistioididae ( one genus, one species), Gnathophyllidae ( one genus, one species), Palaemonidae Palaemoninae ( seven genera, nine species), and Palaemonidae Pontoniinae ( 30 genera, 106 species), including eight new species. The new species are all Pontoniinae: Mesopontonia brevicarpalis sp. nov., Palaemonella komaii sp. nov., Periclimenes crosnieri sp. nov., Periclimenes forgesi sp. nov., Periclimenes loyautensis sp. nov., Periclimenes paralcocki sp. nov., Periclimenes paraleator sp. nov., and Periclimenes pseudalcocki sp. nov. The last six new species are members of the deep-water "Periclimenes alcocki species complex'', which has more than two ( usually four) pairs of dorsolateral telson spines anterior to the posterior telson margin, the cornea is usually reduced, the dactyl of the major second chela is generally flanged and the chela is sometimes covered with small tubercles. The complex is usually found at more than 200m depth in the West Pacific. The species can be distinguished from each other by the armature of ambulatory propod and dactyl, diameter of cornea, rostrum shape and the number of pairs of dorsolateral telson spines. Mesopontonia brevicarpalis sp. nov., from the southeast coast of Africa, is the seventh species of the genus. Palaemonella komaii sp. nov. is very similar to Palaemonella dolichodactylus Bruce, 1991 and Palaemonella hachijo Okuno, 1999. These three species share the features of very long and slender ambulatory pereiopods with the dactyl more than eight times longer than its basal depth and with several long setae on the dorsal dactylar margin.