黄河中游河漫滩(禹渡口-桃花峪)种子植物资源

黄河中游河漫滩有种子植物84科、358属、818种,根据用途资源植物种类有56科270种,可划分为有6类、25亚类.其中含种数较多的依次为:纤维植物类、饲用植物类、药用植物类、抗污染植物类、指示植物类、水土保持植物类.文章分析了该区域的主要资源植物特点,并对资源植物的开发利用和保护提出了建议.     

Spatial and inter-annual variability of the macrobenthic communities within a coastal lagoon (Óbidos lagoon) and its relationship with environmental parameters

The present work aims to analyse spatial and inter-annual variability in the benthic environment within the Óbidos lagoon, assessing the relationships between environmental characteristics and macrobenthic distribution patterns. Sediment samples were collected in February 2001 and 2002 for the study of macrofauna and biogeochemical parameters (sediment grain size, organic matter, organic carbon, chlorophyll a, and phaeopigments). Comparing 2001 to 2002, a general increase in the number of species, diversity and equitability indices was observed throughout the study area. Likewise, there was an increase of phytopigments and organic matter contents in the upper sediment layer. Based on the macrobenthic community patterns and environmental variables three main areas could be distinguished in both years: an outer area near the inlet mostly influenced by the sea, with very depressed number of species and abundance, and dominated by Saccocirrus papillocercus, Lekanesphaera levii, Microphthalmus similis and Nephtys cirrosa; an intermediate area located in the central part of the lagoon characterized by sandy sediment and low organic carbon, and colonized by a high diverse community with Hydrobia ulvae, Cerastoderma edule and Abra ovata as the most characteristic species; and the innermost area of the lagoon with muddy enriched sediments dominated by Heteromastus filiformis, oligochaetes, Scrobicularia plana, Cyathura carinata, Corophium acherusicum, phoronids, insect larvae and Corbula gibba. Deposit-feeders were dominant in the muddy sediments from the inner area, where suspension-feeders were also abundant. Carnivores were associated with clean sandy sediments from the inlet area and herbivores were more abundant within the central area.     

三江平原典型小叶章湿地土壤氨挥发特征及影响因素

采用通气法对三江平原典型草甸小叶章湿地和沼泽化草甸小叶章湿地土壤的氨挥发进行了原位测定,并对其主要影响因素进行了分析。结果表明,二者的氨挥发速率在生长季内的变化趋势基本一致,7月中旬前出现两次挥发高峰和一次低值,之后整体呈严格单调下降趋势,后者的氨挥发速率较高,平均为前者的1.35±0.53倍;二者累计氨挥发量的变化趋势也基本一致,7月中旬前增加迅速,且值比较接近;之后增加缓慢,但其值发生明显分异,表现为后者大于前者;生长季内,典型草甸小叶章湿地土壤的氨挥发总量为6.35 kg N.hm-2,而沼泽化草甸小叶章湿地则为6.87 kg N.hm-2,二者之比为1∶1.08;氮素物质基础不是影响二者氨挥发过程的重要限制因素,大气温度及其所引起的其它温度波动是影响氨挥发速率变化的重要因素;降水及土壤水分波动与散失是引起氨挥发速率局部波动的重要原因;土壤pH和质地是导致氨挥发速率普遍较低的根本原因;而各种因素综合作用的结果则是引起二者氨挥发速率和氨挥发量变化及差异的主要原因。     

三江平原小叶章湿地枯落物分解及主要元素变化动态

应用分解袋法研究了三江平原小叶章湿地枯落物的分解失重及其主要营养元素的变化动态。结果表明,小叶章枯落物的年分解速率为0.257,二次指数模型:Wt/W0=0.0399e-0.545t+0.9601e0.018t(R2=0.945)能更好地描述其分解失重动态。分解过程中,C、N、P、Ca的积累系数(NAI)<100%(P<0.05),元素发生了净释放;K、Na的NAI>100%(P<0.05),元素发生了净积累;Mg、Mn、Fe的NAI值与100%无显著差异(P>0.05),元素既有释放又有积累。分解16个月后,小叶章枯落物各元素总体释放率的大小顺序为:Fe>P>Ca>N>C>Mg>Mn>K>Na,而相应元素的释放量分别为:0.106、0.147、0.971、0.568、65.37、-0.017、-0.114、-0.209和-0.125 g.m-2。     

Evidence for reproductive isolation between two colour morphs of cavity nesting honey bees (Apis) in south India

In south India there are two distinct colour morphs of cavity nesting honey bees: the yellow ‘Plain’ morph and the black ‘Hill’ morph which are collectively known as Apis cerana. We show that the Hill morph is associated with a widely distributed mitochondrial haplotype that is present throughout mainland populations of south east Asian A. cerana. In contrast, the Plain morph, which is apparently confined to low to moderate elevations in India and Sri Lanka, is associated with a unique mitochondrial haplotype that is not present in other cavity nesting honey bees. We further show that in a region of sympatry (Bangalore, Karnataka State) the drone mating flight times of the two colour morphs barely overlap. Combined, drone flight data and the complete separation of mitochondrial haplotypes suggest that the two morphs are reproductively isolated. The Plain morph is distinguished from the Hill morph by the first three abdominal tergites of the worker, which are completely yellow in the Plain morph, whereas in the Hill morph they are black or black with yellow patches. Although the two morphs are generally distinguishable in the field by overall colouration, microscopic examination of the first 3 abdominal tergites is preferred. Received 16 February 2006; revised 11 May 2006; accepted 23 May 2006.     

北极高维度海域海冰嗜冷菌系统发育多样性及其低温水解酶分析

应用样品直接稀释涂布平板、-1℃富集培养和-20℃冷冻24h后富集培养等3种方法,从北极加拿大海盆和格陵兰海的高纬度海域(77°30′N~81°12′N)海冰中分离到37株嗜冷菌。根据其16S rDNA全长序列所进行的系统发育分析表明,分离菌株分属于γ_变形细菌群(γ_Proteobacteria)的Colwellia、Marinobacter、Shewanella、Thalassomonas、Glaciecola、Marinomonas、Pseudoalteromonas和嗜纤维菌_曲挠杆菌_拟杆菌群(Cytophaga_Flexibacter_Bacteroide,CFB)的Flavobacterium、Psychroflexus等9个属。其中有9株菌的16S rDNA序列与已明确鉴定种的相似性在93.4%~96.9%,为潜在的新种。北极加拿大海盆海冰细菌BSi20002与南极威德尔海海冰细菌Marinobactersp.ANT8277的16S rDNA序列相似性为100%,表明在种水平上南、北两极也存在相同的细菌。分离的嗜冷菌在4℃条件下能产生多种大分子物质水解酶类,其中62.6%、51.4%和40.5%的菌株分别能水解Tween_80、明胶和淀粉。     

极地微生物 —— 新天然药物的潜在来源

微生物是极地生态系统的重要组成部分.由于极地独特的地理、气候及环境特点,极地微生物所具有的新颖性与多样性,在科学研究、应用开发等方面都具有重要价值,并逐渐受到人们的广泛关注.有关极地微生物的资源勘探与代谢活性产物研究,已成为国际微生物学研究的热点之一.结合笔者的工作实践,对近年来极地微生物资源的勘探与收集情况进行了介绍,并着重对以医药与生物农药等为目标的极地微生物产活性化合物的研究现状进行了概述,同时还对目前一些影响研究工作开展的限制因素进行了讨论.可以预见,针对极地微生物资源的研究开发工作,将会给新型天然药物的筛选与发现带来新的机遇与突破.     

MH class IIα polymorphism in local and global adaptation of Arctic charr (<Emphasis Type="Italic">Salvelinus alpinus</Emphasis> L.)

Arctic charr, a highly plastic salmonid that inhabits the circumpolar region, colonized its current environment after the last glaciation. Recent colonization limits the capacity of many techniques to define and characterize constituent populations. As a novel approach, we used the major histocompatibility (MH) class IIalpha gene polymorphism as a marker that would characterize the genetic divergence of global Arctic charr populations caused by drift and by local adaptation to pathogens. We were able to detect significant isolation of all the lineages previously defined by mitochondrial DNA sequencing and also isolation of some populations within those groups. We found that most of the polymorphism of the class IIalpha gene was distributed globally, which indicates ancestral selection; however, in most cases, distinctive allele frequencies and specific haplotypes distinguished each population suggesting that recent selection has also occurred. Although all studied populations showed similar MH class IIalpha polymorphisms, we also found variation in which particular amino acid positions were polymorphic and which were constant in the different populations studied. This variation provides a greater adaptive capacity for the MH class IIalpha receptors in Arctic charr and is yet another illustration of the extraordinary plasticity of the species.     

Natural succession of macroalgal-dominated epibenthic assemblages at different water depths and after transplantation from deep to shallow water on Spitsbergen

In the current study, we investigated the primary succession of seaweeds over different time periods at different water depths. Furthermore, we followed the succession of field-grown benthic communities of different successional age, developing on ceramic tiles, prior to and after transplantation from 8 to 0.5 m water depth. The transplantation simulated changes associated with the break up of sea-ice cover, e.g. light regime or wave exposure. For this purpose, we transplanted 12 and 21-month old communities, grown at 8 m water depth, together with a set of sterile tiles, onto rafts, floating in 0.5 m water depth. Our results describe for the first time the succession of macroalgal communities in the Arctic and give important insights into the effect of disturbance of differently aged communities. The primary succession at 0.5 m water depth was mainly driven by Bacillariophyta and filamentous green algae like Urospora sp. and Ulothrix implexa. Twelve-month old communities at 8 m water depth are dominated by members of the Ectocarpales (Phaeophyceae), like Pylaiella littoralis, P. varia, and Ectocarpus siliculosus and the green alga U. implexa, whereas the 21-month old community showed a higher cover of the green algal class Ulvophyceae and sessile invertebrates. After transplantation to near surface conditions, species composition of the communities changed, but this effect was differently strong between communities of different age.     

Temporal patterns of benthic community development in an Arctic fjord (Kongsfjorden, Svalbard): results of a 24-year manipulation study

We investigated temporal patterns of recolonisation and disturbance in a benthic hard bottom community in high-arctic Kongsfjorden from 1980 to 2003 through annual photographic surveys. A manipulative sampling design was applied, where half of the study area (treatment areas) was cleared at the beginning of the study. Twenty-three different taxa and groups of benthic epifauna were found in the photographs. The benthic community structures of treatments and controls converged within the first decade, but significant differences prevailed until ≤13 years after the start of the study. We could distinguish between three different time intervals with increased inter-annual changes. While the observed differences during the first two intervals could be attributed to recolonisation and succession, the changes in interval 3 were mostly due to increased external forcing and characterised by low inter-group and high inter-annual differences. During this interval, brown algae (mainly Desmarestia) and the sea urchin Strongylocentrotus droebachiensis emerged in high densities, while sea anemone populations declined. Different recolonisation patterns for individual species were related to life span, rate of maturity, predators and larval settlement. We could not find a climax stage in the succession for the benthic community at Kvadehuken, presumably due to the constant level of disturbances at the site.