Evolution of body condition‐dependent dispersal in metapopulations

Body condition‐dependent dispersal strategies are common in nature. Although it is obvious that environmental constraints may induce a positive relationship between body condition and dispersal, it is not clear whether positive body conditional dispersal strategies may evolve as a strategy in metapopulations. We have developed an individual‐based simulation model to investigate how body condition–dispersal reaction norms evolve in metapopulations that are characterized by different levels of environmental stochasticity and dispersal mortality. In the model, body condition is related to fecundity and determined either by environmental conditions during juvenile development (adult dispersal) or by those experienced by the mother (natal dispersal). Evolutionarily stable reaction norms strongly depend on metapopulation conditions: positive body condition dependency of dispersal evolved in metapopulation conditions with low levels of dispersal mortality and high levels of environmental stochasticity. Negative body condition‐dependent dispersal evolved in metapopulations with high dispersal mortality and low environmental stochasticity. The latter strategy is responsible for higher dispersal rates under kin competition when dispersal decisions are based on body condition reached at the adult life stage. The evolution of both positive and negative body condition‐dependent dispersal strategies is consequently likely in metapopulations and depends on the prevalent environmental conditions.     

CO2 uptake by the cultivated hemiepiphytic cactus, Hylocereus undatus

The climate of the native tropical forest habitats of Hylocereus undatus, a hemiepiphytic cactus cultivated in 20 countries for its fruit, can help explain the response of its net CO2 uptake to environmental factors. Under wet conditions, about 85% of the total daily net CO₂ uptake occurs at night via Crassulacean acid metabolism, leading to a high water‐use efficiency. Total daily net CO₂ uptake is reduced 57% by only 10 days of drought, possibly involving stomatal closure induced by abscisic acid produced in the roots, which typically occupy a small substrate volume. Total daily net CO₂ uptake for H. undatus is maximal at day/night air temperatures of 30/20°C, optimal temperatures that are higher than those for desert cacti but representative of ambient temperatures in the tropics; its total daily net CO₂ uptake becomes zero at day/night air temperatures of 42/32°C. Stem damage occurs at 45°C for H. undatus, whose photosynthetic cells show little acclimation to high temperatures compared with other cacti and are also sensitive to low temperatures, ‐1.5°C killing half of these cells. Consistent with its shaded habitat, total daily net CO2 uptake is appreciable at a total daily PPF of only 2 mol m2 day' and is maximal at 20 mol m^?2 day^?1, above which photoinhibition reduces net CO₂ uptake. Net CO₂ uptake ability, which is highly correlated with stem nitrogen and chlorophyll contents, changes only gradually (halftimes of 2–3 months) as the concentration of applied N is changed. Doubling the atmospheric CO₂ concentration raises the total daily net CO₂ uptake of H. undatus by 34% under optimal conditions and by even larger percentages under adverse environmental conditions.     

拉萨河谷上段江孜沙棘Hippophea gyantsensis(Rousi) Lian种群的海拔梯度性变异

江孜沙棘[Hippophea gyantsensis(Rousi)Lian]是青藏高原特有的一种广生态幅的小乔木,在拉萨河谷地区的海拔3500~4200m范围内均有分布。前人工作多集中在江孜沙棘果实的开发利用方面,对其基础生态学研究较少。本研究旨在探讨江孜沙棘沿海拔梯度的群落组成和表型变异的规律。为此,在拉萨河谷上段沿海拔梯度由东向西设置了4个样带:3850m、3950m、4050m和4200m,每个样带设置2至3个10m×10m的样方进行研究。首先,详细记录了每个样方内林下维管植物的物种组成、样方内的沙棘盖度、海拔、样方与河岸的实际距离,并用DCA[detrended correspondence analysis(去势对应分析)]排序方法对群落及其组成物种进行排序分析。随机抽取了每个样方内的20个江孜沙棘植株个体,测定其胸径、基径、株高和叶片长度,用回归分析法分析这些变量和海拔之间的关系。研究结果表明,江孜沙棘在拉萨河谷内的主要生境分为4种类型,即:河边砾石滩地、河阶草滩、河边草甸和河边林缘,样方排序结果主要受海拔的影响;同时,江孜沙棘植株的基径、胸径和高度都随着海拔的升高而显著减小,而叶片长度与海拔之间无显著相关。本文研究结果表明,对江孜沙棘而言,海拔所代表的综合环境因子对其分布和表型有显著的影响,而局部光照可能也是影响其表型特征的重要生态因子。     

Climate‐induced changes in the distribution of freshwater fish: observed and predicted trends

1. Climate change could be one of the main threats faced by aquatic ecosystems and freshwater biodiversity. Improved understanding, monitoring and forecasting of its effects are thus crucial for researchers, policy makers and biodiversity managers. 2. Here, we provide a review and some meta‐analyses of the literature reporting both observed and predicted climate‐induced effects on the distribution of freshwater fish. After reviewing three decades of research, we summarise how methods in assessing the effects of climate change have evolved, and whether current knowledge is geographically or taxonomically biased. We conducted multispecies qualitative and quantitative analyses to find out whether the observed responses of freshwater fish to recent changes in climate are consistent with those predicted under future climate scenarios. 3. We highlight the fact that, in recent years, freshwater fish distributions have already been affected by contemporary climate change in ways consistent with anticipated responses under future climate change scenarios: the range of most cold‐water species could be reduced or shift to higher altitude or latitude, whereas that of cool‐ and warm‐water species could expand or contract. 4. Most evidence about the effects of climate change is underpinned by the large number of studies devoted to cold‐water fish species (mainly salmonids). Our knowledge is still incomplete, however, particularly due to taxonomic and geographic biases. 5. Observed and expected responses are well correlated among families, suggesting that model predictions are supported by empirical evidence. The observed effects are of greater magnitude and show higher variability than the predicted effects, however, indicating that other drivers of changes may be interacting with climate and seriously affecting freshwater fish. 6. Finally, we suggest avenues of research required to address current gaps in what we know about the climate‐induced effects on freshwater fish distribution, including (i) the need for more long‐term data analyses, (ii) the assessment of climate‐induced effects at higher levels of organisation (e.g. assemblages), (iii) methodological improvements (e.g. accounting for uncertainty among projections and species’ dispersal abilities, combining both distributional and empirical approaches and including multiple non‐climatic stressors) and (iv) systematic confrontation of observed versus predicted effects across multi‐species assemblages and at several levels of biological organisation (i.e. populations and assemblages).     

Persistent nuclear ribosomal DNA sequence polymorphism in the Amelanchier agamic complex (Rosaceae)

Individual plants of several Amelanchier taxa contain many polymorphic nucleotide sites in the internal transcribed spacers (ITS) of nuclear ribosomal DNA (nrDNA). This polymorphism is unusual because it is not recent in origin and thus has resisted homogenization by concerted evolution. Amelanchier ITS sequence polymorphism is hypothesized to be the result of gene flow between two major North American clades resolved by phylogenetic analysis of ITS sequences. Western North American species plus A. humilis and A. sanguinea of eastern North America form one clade (A), and the remaining eastern North American Amelanchier make up clade B. Five eastern North American taxa are polymorphic at many of the nucleotide sites where clades A and B have diverged and are thought to be of hybrid origin, with A. humilis or A. sanguinea as one parent and various members of clade B as the other parent. Morphological evidence suggests that A. humilis is one of the parents of one of the polymorphic taxa, a microspecies that we refer to informally as A. "erecta." Sequences of 21 cloned copies of the ITS1- 5.8S gene-ITS2 region from one A. "erecta" individual are identical to A. humilis sequence or to the clade B consensus sequence, or they are apparent recombinants of A. humilis and clade B ITS repeats. Amelanchier "erecta" and another polymorphic taxon are suspected to be relatively old because both grow several hundred kilometers beyond the range of one of their parents. ITS sequence polymorphisms have apparently persisted in these two taxa perhaps because of polyploidy and/or agamospermy (asexual seed production), which are prevalent in the genus.      

抗肿瘤药阿霉素诱导Wnt通路抑制因子的表达

研究抗肿瘤药阿霉素对Wnt通路抑制因子FrpHE(frizzled-related protein)和DKK-1(Dickkopf-1)表达的作用.将抗肿瘤药阿霉素加入到人肝癌HepG2(HepG2,含野生型p53;Hep3B,p53缺失)、人大肠癌(Lovo,含野生型p53)和人神经胶质瘤细胞(U251,p53突变)细胞株中.以RT-PCR技术检测阿霉素对Wnt通路抑制因子FrpHE和DKK-1的表达调节作用,以流式细胞术检测在肿瘤细胞中Wnt通路的关键调节因子β-catenin的表达.在加入阿霉素24h后FrpHEmRNA表达水平在人肝癌细胞(HepG2,含野生型p53;Hep3B,p53缺失)中与对照组相比表达水平显著增加.在人大肠癌细胞(Lovo,含野生型p53)和人神经胶质瘤细胞(U251,p53突变型)细胞中,未见FrpHE mRNA表达.DKK-1mRNA表达水平在人肝癌细胞(HepG2,含野生型p53;Hep3B,p53缺失)、人大肠癌细胞(Lovo,含野生型p53)和人神经胶质瘤细胞(U251,p53突变型)中与对照组相比表达水平显著增加.β-catenin的阳性细胞百分比强度和平均荧光量强度与对照组相比,表达水平降低.提示化疗药阿霉素能明显诱导抑制剂FrpHEmRNA和DKK-1mRNA的表达.     

Checklist of the Caesalpinioideae (Leguminosae) of Equatorial Guinea (Annobón, Bioko and Río Muni)

This study provides a checklist of the Caesalpinioideae (Leguminosae) present in Equatorial Guinea, comprising 52 genera and 124 taxa. Seven species are known from Annobón, 33 from Bioko and 109 from Río Muni. The best represented genus is Senna with eight species. In addition, bibliographic references for Caesalpinioideae (Leguminosae) from Equatorial Guinea have been gathered and checked. Fourteen species are included based on literature records, because their distribution ranges suggest they may occur in Equatorial Guinea, 11 introduced species could be naturalized, and 45 taxa are recorded for the first time from the country. This represents an increase of over 35% in the floristic knowledge of Caesalpinioideae from Equatorial Guinea. A statistical summary is presented at the end of the checklist.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 541–562.     

Clinical-scale generation of multi-specific anti-fungal T cells targeting Candida,Aspergillus and mucormycetes

Background aimsInvasive fungal infections, in particular, infections caused by Candida, Aspergillus and mucormycetes, are a major cause of morbidity and mortality in patients undergoing allogeneic hematopoietic stem cell transplantation. Adoptive transfer of donor-derived anti-fungal T cells shows promise to restore immunity and to offer a cure. Because T cells recognize only specific epitopes, the low rate of patients in which the causal fungal pathogen can be identified and the considerable number of patients with co-infection with several genera or species of fungi significantly limit the application of adoptive immunotherapy.MethodsUsing the interferon-γ secretion assay, we isolated multi-specific human anti-fungal T cells after simultaneous stimulation with cellular extracts of Aspergillus fumigatus, Candida albicans and Rhizopus oryzae. Cells were phenotypically and functionally characterized by flow cytometry.ResultsOf a total of 1.1 × 10⁹ peripheral blood mononuclear cells, a median number of 5.2 × 10⁷ CD3⁺CD4⁺ T cells was generated within 12 days. This cell population consisted of activated memory T_H1 cells and reproducibly responded to a multitude of Aspergillus spp., Candida spp. and mucormycetes with interferon-γ production. On re-stimulation, the generated T cells proliferated and enhanced anti-fungal activity of phagocytes and showed reduced alloreactivity compared with the original cell fraction.ConclusionsOur rapid and simple method of simultaneously generating functionally active multi-specific T cells that recognize a wide variety of medically relevant fungi may form the basis for future clinical trials investigating adoptive immunotherapy in allogeneic hematopoietic stem cell transplantation recipients with invasive fungal infection.