人MCP cDNA在NIH3T3细胞中表达及功能研究

通过构建表达人膜辅因子蛋白ＭＣＰ编码区全长ｃＤＮＡ的重级载体ｐｃＤＮＡ３ＭＣＰ,以磷酸钙沉淀法转染ＮＩＨ３Ｔ３细胞,用Ｇ４１８筛选阳性克隆,并鉴定ＭＣＰ ｃＤＮＡ在细胞中的表达。将血清梯度稀释并与细胞孵育,然后检测细胞活力：灭活的人血清不能引起对照细胞与ＭＣＰ转染细胞的胞毒作用,而新鲜人血清可使对照细胞发生补体依赖的细胞毒反应,ＭＣＰ转染细胞由于ＭＣＰ蛋白的合成,细胞受到保护不发生该反应。另外,Ｍ     

Historical biogeography of Hexabathynella , a cosmopolitan genus of groundwater Syncarida (Crustacea, Bathynellacea, Parabathynellidae)

Hexabathynella is the only cosmopolitan genus of the order Bathynellacea (Crustacea). The known species number 18, found in Europe (9), Africa (1), South America (2), North America (3) and Australia and New Zealand (3). Phylogenetic analysis suggests that the least derived species are those from South America and the most derived those from the Iberian Peninsula, North America and Australia. The five species with the most plesiomorphic characters occur in salt or brackish water, which supports a marine origin for the genus. Phylogenetic and biogeographical analyses suggest that the distribution of the genus can be explained by dispersion and a double vicariant biogeographical model based on plate tectonics and the evolution of the Tethys during the Mesozoic and Cenozoic.  © 2003 The Linnean Society of London . Biological Journal of the Linnean Society , 2003, 78 , 457–466.     

Between Xylem and Phloem: The Genetic Control of Cambial Activity in Plants

Abstract: Post-embryonic development is controlled by two types of meristems: apical and lateral. There has been considerable progress recently in understanding the function of root and shoot apical meristems at the molecular level. Knowledge of analogous processes in the lateral, or secondary, meristems, i.e. the vascular cambium or cork cambium, is, however, rudimentary. This is despite the fact that much of the diversity in the plant kingdom is based on the differential functions of these meristems, emphasizing the importance of lateral meristems in the development of different plant forms. The vascular cambium is particularly important for woody plants, but it also plays an important role during the development of various herbaceous species, such as Arabidopsis thaliana. In this review, we focus on the two basic functions of cambial activity: cell proliferation and pattern formation.     

Effect of strain-specific hypersensitive resistance on spatial patterns of virus spread

Spatial patterns of spread were compared between strains of Bean yellow mosaic virus (BYMV) that differ in causing systemic necrotic (hypersensitive) or non‐necrotic symptoms in narrow‐leafed lupin (Lupinus angustifolius). Both types of BYMV were spread naturally by aphids from adjacent infected pasture into a large lupin block (‘natural spread site’), or from clover plants introduced as virus sources into two field experiments with lupin. Cumulative spatial data for plants with disease symptoms from a range of times in the growing period were assessed using Spatial Analysis by Distance IndicEs (SADIE). At the‘natural spread site’, with non‐necrotic BYMV, the extent of clustering of plants with symptoms increased gradually over time, while with necrotic BYMV there was less clustering and no increase over time. In both experiments, for the type of BYMV that was introduced into a plot, there was a gradual increase in clustering, but with this being greater with non‐necrotic BYMV. In the second experiment, there was also significant clustering of plants with symptoms of non‐necrotic BYMV in plots without introduced non‐necrotic foci but not for necrotic BYMV in plots without introduced necrotic foci. When clustering data for plants with newly recorded symptoms was tested for spatial association between successive assessment dates, association was positive for both BYMV types though stronger for the non‐necrotic type, declining as the temporal lag increased. Generally, association was strongest for assessments 2–3 wk apart, corresponding approximately to the period for BYMV to move systemically in plants and for obvious symptoms to appear in shoot tips. Contour maps for local association between dates showed that the strongest spatial associations were from coincidence of infection gaps rather than infection patches. The combination of information from clustering and association analysis showed that spread of non‐necrotic BYMV is less diffuse, with considerably more localised infection surrounding the infection sources. This work demonstrates how spatial virus spread can be diminished when hypersensitive (necrotic) resistance is deployed, and the limitations associated with employing hypersensitivity that is strain specific.     

Primary Seed Dispersal by Red Howler Monkeys and the Effect of Defecation Patterns on the Fate of Dispersed Seeds1

The effectiveness of a seed disperser depends on the quantity and quality of dispersal. The quality of dispersal depends in large part on factors that affect the post–dispersal fate of seeds, and yet this aspect of dispersal quality is rarely assessed. In the particular case of seed dispersal through endozoochory, the defecation pattern produced has the potential of affecting the fate of dispersed seeds and consequently, dispersal quality and effectiveness. In this study, I assessed the effects of dung presence and dung/seed densities on seed predation by rodents and secondary dispersal by dung beetles. In particular, I compared seed fates in clumped defecation patterns, as those produced by howler monkeys, with seed fates in scattered defecation patterns, as those produced by other frugivores. I also determined the prevalence of red howler monkeys (Alouatta seniculus) as seed dispersers at the plant community level in Central Amazonia by determining the number of species they dispersed in a 25–month period. I found that dung presence and amount affected rodent and dung beetle behavior. Seed predation rates were higher when dung was present, and when it was in higher densities. The same number of seeds was buried by dung beedes, in dumped versus scattered defecation patterns, but more seeds were buried when they were inside large dung–piles versus small piles. Seed density had no effect on rodent or dung beetle behavior. Results indicate that caution should be taken when categorizing an animal as a high or low quality seed disperser before carefully examining the factors that affect the fate of dispersed seeds. Red howler monkeys dispersed the seeds of 137 species during the study period, which is the highest yet reported number for an Alouatta species, and should thus be considered highly prevalent seed dispersers at the plant community level in Central Amazonian terra firme rain forests.     

Spatial patterns of leaf nutrient traits of the plants in the Loess Plateau of China

The spatial patterns of leaf nutrient traits of plants in seven sites, Yangling, Yongshou, Tongchuan, Fuxian, Ansai, Mizhi and Shenmu, standing from south to north in the Loess Plateau of China, were studied. The results showed that of the 126 plant samples in the Loess Plateau, the mean leaf organic carbon (C), nitrogen (N), phosphorus (P) and potassium (K) were 43.8, 2.41, 0.16 and 1.67%, respectively, and ranked in the order of C > N > K > P. Leaf C, N, P and K ranged from 32.6 to 54.8%, 0.82 to 4.58%, 0.06 to 0.35%, and 0.24 to 4.21%, respectively. The mean leaf C/N, C/P and N/P ratios were 21.2, 312 and 15.4, respectively. It is indicated that leaf N in the Loess Plateau was significantly higher than those in Chinese and global flora, but leaf P was significantly lower than that in global flora, which resulted in a higher N/P ratio in the Loess Plateau. The results also showed that leaf C, N, P, K, C/N and C/P ratios varied significantly among the seven life-form groups, which were trees, shrubs, herbages, evergreen trees, deciduous trees, C₃ and C₄ herbages, but leaf N/P ratio differed little among the seven life-forms. In the sampled species in the Loess Plateau, leaf C was negatively correlated with leaf N, P and K, while leaf N, P and K were positively correlated with one another. In general, leaf N/P ratio increased as the latitude and annual solar radiation increased and the mean annual rainfall and mean annual temperature decreased.     

Body pigmentation pattern to assess introgression by hatchery stocks in native Salmo trutta from Mediterranean streams

Five qualitative and seven quantitative colouration and spotting pattern features were measured in 23 brown trout Salmo trutta populations and two hatchery stocks. Simultaneously, the LDH‐C1 *, a diagnostic locus fixed for *90 and *100 alleles in stocking and native populations from southern Europe, respectively, was analysed to classify the brown trout studied according to their origin: native, hatchery stock and hybrids. The three genotypes showed significant differences in the colouration and spotting features and a discriminant function analysis could correctly identify 79% of the individuals. The most discriminating variables were dorsal fin margin colour, number of opercular spots, presence of the preopercular mark and diameter of black spots. Given the low cost, ease and possibility of field identification of native fish, the results indicate great opportunities for the application of morphological‐based classification models on the conservation and management of native brown trout stocks.     

The role of spatial scale and the perception of large-scale species-richness patterns

Despite two centuries of exploration, our understanding of factors determining the distribution of life on Earth is in many ways still in its infancy. Much of the disagreement about governing processes of variation in species richness may be the result of differences in our perception of species‐richness patterns. Until recently, most studies of large‐scale species‐richness patterns assumed implicitly that patterns and mechanisms were scale invariant. Illustrated with examples and a quantitative analysis of published data on altitudinal gradients of species richness (n = 204), this review discusses how scale effects (extent and grain size) can influence our perception of patterns and processes. For example, a hump‐shaped altitudinal species‐richness pattern is the most typical (c. 50%), with a monotonic decreasing pattern (c. 25%) also frequently reported, but the relative distribution of patterns changes readily with spatial grain and extent. If we are to attribute relative impact to various factors influencing species richness and distribution and to decide at which point along a spatial and temporal continuum they act, we should not ask only how results vary as a function of scale but also search for consistent patterns in these scale effects. The review concludes with suggestions of potential routes for future analytical exploration of species‐richness patterns.