海洋酸化的影响及主要国家研究部署

全球变暖带来的海洋酸化问题对海洋环境造成的影响已经逐渐引起国际科学界的重视。全球海洋的酸化状况已经成为既成事实,对珊瑚礁、甲壳类动物甚至整个海洋生态系统都造成了不利影响。美国、欧洲以及日本等国都在重要海洋研究计划中做了相关部署,旨在深入了解海洋酸化的机理、可能造成的影响以及相关应对措施。     

Glycosaminoglycan synthesis by embryonic fibroblasts is age-dependent and modulated by environmental factors

Summary The glycosaminoglycans (GAG) secreted by primary fibroblasts cultures removed from chick embryo skin after 7 and 14 days of incubation have been investigated. Differences in GAG composition have been detected, depending on age and on the composition of the nutrient medium. This study was supported in part by an Italian Ministero Publica Istruzione grant.     

Simultaneous monitoring by optical techniques of respiratory chain and intracellular pH in toad ventricle strip.

Intracellular pH and oxidative metabolism can be measured in toad ventricle strips simultaneously by the use of the pH indicator dye, neutral red, and a rapid scanning spectrophotometer. The effects of hypoxia and acidification on mechanical function are approximately additive. The decrease in tension due to slight acidification is probably through an effect on the portion of the twitch tension supported by anaerobic metabolism.     

Induction of vanadium accumulation and nuclear sequestration causing cell suicide in human Chang liver cells

Very little is known about the modulation of vanadium accumulation in cells, although this ultratrace element has long been seen as an essential nutrient in lower life forms, but not necessarily in humans where factors modulating cellular uptake of vanadium seem unclear. Using nuclear microscopy, which is capable of the direct evaluation of free and bound (total) elemental concentrations of single cells we show here that an NH₄Cl acidification prepulse causes distinctive accumulation of vanadium (free and bound) in human Chang liver cells, concentrating particularly in the nucleus. Vanadium loaded with acidification but leaked away with realkalinization, suggests proton-dependent loading. Vanadyl(4), the oxidative state of intracellular vanadium ions, is known to be a potent source of hydroxyl free radicals (OH^.). The high oxidative state of nuclei after induction of vanadyl(4) loading was shown by the redox indicator methylene blue, suggesting direct oxidative damage to nuclear DNA. Flow cytometric evaluation of cell cycle phase-specific DNA composition showed degradation of both 2N and 4N DNA phases in G₁, S and G₂/M cell cycle profiles to a solitary 1N DNA peak, in a dose-dependent manner, effective from micromolar vanadyl(4) levels. This trend was reproduced with microccocal nuclease digestion in a time response, supporting the notion of DNA fragmentation effects. Several other approaches confirmed fragmentation occurring in virtually all cells after 4 mM V(4) loading. Ultrastructural profiles showed various stages of autophagic autodigestion and well defined plasma membrane outlines, consistent with programmed cell death but not with necrotic cell death. Direct intranuclear oxidative damage seemed associated with the induction of mass suicide in these human Chang liver cells following vanadium loading and nuclear sequestration.     

Vegetation structure and primary production in acidified lakes in southwestern Sweden

Summary Research during the last two decades has clearly pointed out that dramatic ecosystem changes have occured in lakes due to deposition of acid substances and decreased pH. Today a large number of lakes and running waters in Scandinavia are suffering biological damage with disappearing fish populations, overgrowth of the bottom by mosses and filamentous algae, reduced invertebrate fauna, increased transparency etc.—Of all documented biological changes the effect on macrophyte succession, in particular that ofSphagnum, is the most striking effect. Along with the growth of filamentous algae, these changes have brought about major shifts in the composition of the primary producers. The biomass in one lake was estimated to be 6.5 t (dry wt) corresponding to about 24 g m^–2, the relevant proportions being 52% forSphagnum, 34% forLobelia and 15% forIsoetes. Percentage production in the whole lake is 54% forSphagnum, 29% forLobelia and 17% forIsoetes, which gives an estimated production of 2.9 t yr^–1 or 9 g m^–2 yr^–1.Sphagnum is a recent flora element and its occurrence is related to the acidification of the lakes. The investigations also show that the growth ofLobelia is reduced in acid lakes compared to other oligotrophic lakes due to shading by the benthic mat of filamentous algae, detritus andSphagnum debris.—One can conclude that there are several quantitative and qualitative changes in the macrophyte community which are related to acidification. One can also conclude that liming of lakes cause elimination ofSphagnum and some increase in the production ofIsoetids.     

Simultaneous monitoring by optical techniques of respiratory chain and intracellular pH in toad ventricle strip

Summary Intracellular pH and oxidative metabolism can be measured in toad ventricle strips simultaneously by the use of the pH indicator dye, neutral red, and a rapid scanning spectrophotometer. The effects of hypoxia and acidification on mechanical function are approximately additive. The decrease in tension due to slight acidification is probably through an effect on the portion of the twitch tension supported by anaerobic metabolism.Acknowledgments. This work was supported by PHS grants HL 17391, Am 17876 and HL 05208. J.-J.S. is aspirant au Fonds National de la Recherche Scientifique (Belgium).     

北运河(通州段)浮游植物群落与水体营养状况分析

随着北运河流域内用水量和排污量的不断增加,河流污染严重.为改善这种现状,在2010年对北运河(通州段)的浮游植物与理化因素的检测与分析,以期为北运河干流的综合治理以及生态修复提供依据.监测结果显示:北运河五项理化指标的TSIM值平均92.6,Chla达到135.49 μg/L,水体为富营养.主要污染物是CODcr、BO...     

北京温榆河浮游藻类与水质分析

2006年的监测结果显示,温榆河CODM。BOD5、NH4-N、TP和TN含量大于我国地表水环境质量V类标准的1．3～11．7倍,主要污染物为总氮、氨氯和总磷;五项指标（SS、SD、CODMn,TP、TN）的TSIM值为75．11～119．45,属于富营养型水体。温榆河4个监测断面共检出浮游藻类6门148种,绿藻种类最多（48％）,其次是硅藻（20．9％）、蓝藻（18．2％）,优势种群均为富营养型水体指示种。温榆河浮游藻类密度大,平均为3179．01×10^4 cells／L,绿藻占优势（75．6％）,蓝藻次之（14．6％）。     

Quantitative genetics of zooplankton life histories

Quantitative genetic techniques are powerful tools for use in understanding the microevolutionary process. Because of their size, lifespan, and ease of culture, many zooplankton species are ideal for quantitative genetic approaches. As model systems, studies of zooplankton life histories are becoming increasingly used for examination of the central paradigms of evolutionary theory. Two of the fundamental empirical questions that zooplankton quantitative genetics studies can answer are: 1) How much genetic variance exists in natural populations for life history traits? 2) What is the empirical evidence for trade-offs that permeate life history theory based on optimality approaches? A review of existing data onDaphnia indicates substantial genetic variance for body size, clutch size, and age at first reproduction. Average broad-sense heritabilities for these three characters across 19 populations of 6 species are 0.31, 0.31, and 0.34, respectively. Although there is some discrepancy between the two pertinent studies that were designed to decompose the total genetic variance into its additive and non-additive components, a crude average seems to suggest that approximately 60% of the total genetic variance has an additive basis. The existing data are somewhat inconsistent with respect to presence/absence of trade-offs (negative genetic correlations) among life history traits. A composite of the existing data seems to argue against the existence of strong trade-offs between offspring size and offspring number, between present and future reproduction, and between developmental rate and fecundity. However, there is some evidence for a shift toward more negative (less positive) covariances in more stressful environments (e.g., low food). Zooplankton will prove to be very useful in future study in several important areas of research, including the genetics and physiology of aging, the importance of genotype-environment interaction for life history traits, and the evolution of phenotypic plasticity.     

生物多样性与针叶林生态系统过程的关系

在过去10年中，生物多样性与生态系统过程的关系成为生态学中最具争议和挑战性的话题。生态学家们围绕植物组成和多样性与生态系统过程的关系、生物多样性与陆地生态系统的生物地球化学循环的关系、土壤生物多样性赇生态系统过程的影响、生态系统的功能多样性和组成对生态系统过程的影响、生物多样性与生态系统的稳定性以及生物多样性与生态系统过程对全球变化的响应等方面做了大量的开创性研究。川西亚高山针叶林是我国的生物多样性宝库和世界生物多样性的热点地区。迄今为止，有关川西亚高山针叶林生物多样性和生态过程的研究还相当有限，有关生物多样性与生态系统过程关系的研究尚未见报道。因此，建议在未来川西亚高山针叶林生态过程研究中加强生物多样性与针叶林生产力的关系，生物多样性和生物地球化学循环的关系、土壤生物多样性与生态系统过程的互动、地下／地上部分生物多样性的关系、生物多样性和生态过程对全球变化的响应等研究。     

Evolution and biology of supernumerary B chromosomes

B chromosomes (Bs) are dispensable components of the genome exhibiting non-Mendelian inheritance and have been widely reported on over several thousand eukaryotes, but still remain an evolutionary mystery ever since their first discovery over a century ago [1]. Recent advances in genome analysis have significantly improved our knowledge on the origin and composition of Bs in the last few years. In contrast to the prevalent view that Bs do not harbor genes, recent analysis revealed that Bs of sequenced species are rich in gene-derived sequences. We summarize the latest findings on supernumerary chromosomes with a special focus on the origin, DNA composition, and the non-Mendelian accumulation mechanism of Bs.     

Bau und Funktion der Nukleolen

Summary In previous years the composition and function of chromosomes have been analyzed to a considerable extent, in contrast to the small number of investigations that have been made on nucleoli. There exist at present many conflicting opinions about the structure and function of the nucleolus, and therefore a critical survey of the facts and theories about the nucleolar substance appears necessary.The structure, chemical composition and metabolism of the nucleoli of various cells are described in this publication. The regulation of the size and function of the nucleolus is also discussed.It is concluded that the size and structure of the nucleolus is organ- and species-specific. A rapid synthesis of RNA and proteins occurs in the nucleolus. After a short interval, this disappears; and it is therefore concluded that the nucleolus must have a high turnover of these substances. The size and function of the nucleoli depends on the energy state of the cytoplasm.It appears that the nucleolus can synthesize proteins which can be utilized by the chromosomes during their genetic function.     

Microbiome–health interactions in older people

Alterations in the composition and function of the gut microbiome have been implicated in a range of conditions and diseases. Culture-dependent and culture-independent studies both showed that older people harbour a gut microbiome that differs in composition from that of younger adults. Detailed analyses have identified discrete microbiota subtypes that characterize intermediates between a high diversity microbiota found in healthy community-dwelling subjects and a low diversity microbiota typical for elderly living in long-term residential care. There are also alterations in the microbiome composition associated with biological age, independent of health status. Even after adjusting for confounding factors such as age and medication, trends in microbiota composition correlate with gradients in clinical metadata particularly frailty and inflammatory status. There are few known mechanisms by which these associations might be causative rather than consequential, and this is a subject of intensive research. The strongest candidate effectors are microbial metabolites that could impact host energy balance, act as signalling molecules to modulate host metabolism or inflammation, and potentially also impact on the gut–brain axis.     

Protein digestion in the sea gooseberryPleurobranchia bachei A. Agassiz (Ctenophora: Tentaculata)

Summary Peaks of proteolytic activity of pharyngeal juice occur at pH 5.75 and pH 7.5. The proteases responsible for digestion include a tryptic alkaline protease and a thiol-activated acid protease which is probably cathepsin B. Levels of proteolytic activity parallel those of other carnivorous invertebrates which feed on zooplankton.This study was supported by operating grants from the National Research Council of Canada.We are grateful to Betsy Sweeney for her technical assistance.     

Effect of diet on the mitotic activity and rate of cytolysis of intestinal epithelial cells in tadpoles of the common toad, Bufo bufo (Amphibia, Anura)]

Effects of diet on the mitotic activity and cellular mortality rate of the intestinal epithelium cells have been examined in Toad tadpoles. As yolk is utilized, the composition of diet has little effect on these 2 parameters. As development goes on, the cellular mortality rate increases with dietary carbohydrate, fat or protein supplementation. But only the fats affect the mitotic activity.     

Function and evolution of channels and transporters in photosynthetic membranes

Chloroplasts from land plants and algae originated from an endosymbiotic event, most likely involving an ancestral photoautotrophic prokaryote related to cyanobacteria. Both chloroplasts and cyanobacteria have thylakoid membranes, harboring pigment-protein complexes that perform the light-dependent reactions of oxygenic photosynthesis. The composition, function and regulation of these complexes have thus far been the major topics in thylakoid membrane research. For many decades, we have also accumulated biochemical and electrophysiological evidence for the existence of solute transthylakoid transport activities that affect photosynthesis. However, research dedicated to molecular identification of the responsible proteins has only recently emerged with the explosion of genomic information. Here we review the current knowledge about channels and transporters from the thylakoid membrane of Arabidopsis thaliana and of the cyanobacterium Synechocystis sp. PCC 6803. No homologues of these proteins have been characterized in algae, although similar sequences could be recognized in many of the available sequenced genomes. Based on phylogenetic analyses, we hypothesize a host origin for most of the so far identified Arabidopsis thylakoid channels and transporters. Additionally, the shift from a non-thylakoid to a thylakoid location appears to have occurred at different times for different transport proteins. We propose that closer control of and provision for the thylakoid by products of the host genome has been an ongoing process, rather than a one-step event. Some of the proteins recruited to serve in the thylakoid may have been the result of the increased specialization of its pigment-protein composition and organization in green plants.     

Prokaryotic genetic code

The prokaryotic genetic code has been influenced by directional mutation pressure (GC/AT pressure) that has been exerted on the entire genome. This pressure affects the synonymous codon choice, the amino acid composition of proteins and tRNA anticodons. Unassigned codons would have been produced in bacteria with extremely high GC or AT genomes by deleting certain codons and the corresponding tRNAs. A high AT pressure together with genomic economization led to a change in assignment of the UGA codon, from stop to tryptophan, in Mycoplasma.     

Cardiolipin, the heart of mitochondrial metabolism

Cardiolipin is a unique phospholipid, which is almost exclusively localized in the mitochondrial inner membrane where it is synthesized from phosphatidylglycerol and cytidinediphosphate-diacylglycerol. After primary synthesis, the mature acyl chain composition of cardiolipin is achieved by at least two remodeling mechanisms. In the mitochondrial membrane cardiolipin plays an important role in energy metabolism, mainly by providing stability for the individual enzymes and enzyme complexes involved in energy production. Moreover, cardiolipin is involved in different stages of the mitochondrial apoptotic process and in mitochondrial membrane dynamics. Cardiolipin alterations have been described in various pathological conditions. Patients suffering from Barth syndrome have an altered cardiolipin homeostasis caused by a primary deficiency in cardiolipin remodeling. Alterations in cardiolipin content or composition have also been reported in more frequent diseases such as diabetes and heart failure. In this review we provide an overview of cardiolipin metabolism, function and its role in different pathological states. Received 16 January 2008; received after revision 26 February 2008; accepted 26 March 2008     

Marine diatoms affecting the stability of oil-in-water emulsions and hydrocarbon distribution in sea water

Summary The importance of phytoplankton in stabilizing oil-in-water emulsion and affecting hydrocarbon distribution in the sea was studied by using marine diatoms. All microalgae tested increased emulsion stability and favored the presence of polycyclic aromatics in the sea water.     

Basement membrane components are key players in specialized extracellular matrices

More than three decades ago, basement membranes (BMs) were described as membrane-like structures capable of isolating a cell from and connecting a cell to its environment. Since this time, it has been revealed that BMs are specialized extracellular matrices (sECMs) with unique components that support important functions including differentiation, proliferation, migration, and chemotaxis of cells during development. The composition of these sECM is as unique as the tissues to which they are localized, opening the possibility that such matrices can fulfill distinct functions. Changes in BM composition play significant roles in facilitating the development of various diseases. Furthermore, tissues have to provide sECM for their stem cells during development and for their adult life. Here, we briefly review the latest research on these unique sECM and their components with a special emphasis on embryonic and adult stem cells and their niches.