广州市蕨类植物物种多样性研究

依据文献、标本与野外调查,简要回顾了历史上记录的广州蕨类植物,阐明了广州目前分布的蕨类植物的种类、区系特点、生态与地理分布、以及珍稀蕨类植物的种类与保护现状.广州地区有蕨类植物37科82属176种,其中乔芒萁(Dicranopteris gigantea)、刺边膜蕨(Hymenophyllm spinosum)和裸果鳞毛蕨(Dryopteris gymnosora)为广东分布新记录.广州蕨类植物区系以金星蕨科(Thelypteridaceae)、鳞毛蕨科(Dryopteridaceae)、水龙骨科(Polypo-diaceae)、蹄盖蕨科(Athyriaceae)和风尾蕨科(Pteridaceae)的植物最为丰富,没有本地特有种,亚洲热带亚热带分布成分和东亚分布成分占绝对优势.这176种蕨类植物中,约80%的种类生活在密林阴湿生境,约20%生活在疏林或灌草丛干旱生境,只有2种水生蕨类植物.在水平分布上,广州蕨类植物呈北多南少的分布格局,约90%的种类汇集在广州东北部的从化山区,74种在广州仅见于该山区.从物种多度上看,个体数量多(Cop2)的有33种,尚多(Cop1)的有48种,稀少(Sp)的有53种,很少(So1)的有41种.华南马尾杉(Phlegmariurus austrosbzicus)、福建观音座莲(Angiopteris fokiensis)、刺边膜蕨(Hymenophy llum spmosum)、粗齿桫椤(Alsophila denticulata)、小黑桫椤(A.m etteniana)、黑桫椤(A.podophylla)、桫椤(A.spinulosa)、水蕨(Ceratopteris thdictroides)、羽裂叶双盖蕨(Diplazium tomitaroanum)、闽浙圣蕨(Dictyocline mingchegensts)、微毛凸轴蕨(Metathelypteris adscendens)、峨眉茯蕨(Leptogramma scdlanll)、苏铁蕨(Brainea insignis)、珠芽狗脊(Woodwardia prolifera)和黑鳞复叶耳蕨(Arachniodes nigrospinosa)等15种被评估为广州的珍稀植物,它们亟待有效的保护.     

Extracellular Alix regulates integrin-mediated cell adhesions and extracellular matrix assembly

Alix (ALG-2-interacting protein X), a cytoplasmic adaptor protein involved in endosomal sorting and actin cytoskeleton assembly, is required for the maintenance of fibroblast morphology. As Alix has sequence similarity to adhesin in Entamoeba histolytica, and we observed that Alix is secreted, we determined whether extracellular Alix affects fibroblast morphology. Here, we demonstrate that secreted Alix is deposited on the substratum of non-immortalized WI38 fibroblasts. Antibody binding to extracellular Alix retards WI38 cell adhesion and spreading on fibronectin and vitronectin. Alix knockdown in WI38 cells reduces spreading and fibronectin assembly, and the effect is partially complemented by coating recombinant Alix on the cell substratum. Immortalized NIH/3T3 fibroblasts deposit less Alix on the substratum and have defects in α₅β₁-integrin functions. Coating recombinant Alix on the culture substratum for NIH/3T3 cells promotes α₅β₁-integrin-mediated cell adhesions and fibronectin assembly, and these effects require the aa 605–709 region of Alix. These findings demonstrate that a sub-population of Alix localizes extracellularly and regulates integrin-mediated cell adhesions and fibronectin matrix assembly.     

Raccoon ecology database: A resource for population dynamics modelling and meta-analysis

The value of scientific studies increases and is extended when their data are stored in a manageable and accessible format. This is demonstrated through development of a raccoon ecology database (REDB) to store, manage and disseminate available peer-reviewed and unpublished data on raccoon (Procyon lotor) biology, ecology and raccoon rabies, including citations for data sources. Over 800 documents were identified and citations for them entered into the database as literature references. Approximately 1000 trait values were entered from almost 200 of these sources. These data included estimates of population density, survival rates, rabies incubation period, litter size, body weight, dispersal distance and home-range size, often by age or sex class. Each datum is linked to a citation for its source, and to information about location and land use in the study area, time of year the study was undertaken, sample size, and variance. The relational database design enables querying and easy updating and manipulation of data.

The relational data model is presented, as is its application in further developing an individual-based, spatially-explicit population model of raccoon rabies. Using information queried from the REDB benefits model development by: i) assessing the appropriateness of input parameter values, ii) providing sources for citing input values, iii) parameterising the model to different geographic regions, iv) enabling meta-analyses for evaluating model structure, as well as further contributing to parameterisation at specific locations, and v) providing biologically appropriate parameter input values for model sensitivity testing. The REDB is a useful research resource that will increase in value with ongoing inclusion of data from future raccoon and raccoon rabies studies and serves as a model for database design and research applications to other species. The database and an empty database for use with other species are available online (http://redb.nrdpfc.ca).     

Simple representation of physiological regulations in a model of lactating female: application to the dairy goat

A dynamic model of the lactating dairy goat, combining a minimum of mechanistic representations of homeorhetic regulations and a long-term approach, was developed. It describes (i) the main changes in body weight, dry-matter intake, milk production and composition of a dairy goat; (ii) the succession of pregnancy and lactation throughout the productive life; and (iii) the major changes in dynamics induced by the female profile (production potential and body weight at maturity). The model adopts a 'pull' approach including a systematic expression of the production potential and not representing any feed limitation. It involves three sub-systems. The reproductive events sub-system drives the dynamics through time with three major events: service, kidding and drying off. It also accounts for the effect of production potential (kg of milk at the peak of lactation) and lactation number (potential reached at the fourth lactation). The regulating sub-system represents the homeorhetic mechanisms during pregnancy and lactation with two sets of theoretical hormones, one representing gestation and the other lactation. The operating sub-system describes the main physiological flows and the energetic requirements linked to these functions through a compartmental structure. Simulations were run in order to test (i) the behaviour of the model at the scale of the productive life for an average profile of female (60 kg at maturity and 4 kg of milk at peak); (ii) the sensitivity of the simulated dynamics (mainly milk production and body reserves) to the production potential and body weight at maturity; (iii) external validation with comparison of model outputs to data from the experimental flock of Grignon and data from the French milk record organization (French organism in charge of animal recording for dairy farmers). The results at the scale of one productive life show the model simulates a relevant set of dynamics. The sensitivity analysis suggests that the model fairly well simulates the link between a female's ability to produce and mobilise reserves. Finally, external validation confirms the model's ability to simulate a relevant set of physiological dynamics while pointing out some limits of the model (simulation of milk fat and protein content dynamics, for example). The results illustrate the relevance of the model in simulating biological dynamics and confirm the possibility of including minimum representations of homeorhetic regulations with a simple structure. This simplicity gives an opportunity to integrate this basic element in a herd simulator and test interactions between females' regulations and management rules.     

Reforestation of abandoned pasture on Hokkaido, northern Japan: effect of plantations on the recovery of conifer-broadleaved mixed forest

When pasture land is abandoned, there are, in many cases, inhibitory factors that slow the rate of transition to a natural vegetation. Accordingly, the planned management of restoration has become an important issue in various parts of the world, where environmental conditions can vary widely. Although tree plantations are widely used as a management tool for restoration, there have been few studies addressing the practical aspects of the procedure. I examined effects of tree plantations within the framework of an evaluation of methods for restoring abandoned pasture on Hokkaido, northern Japan. I developed and analyzed vegetation maps spanning the past 57 years for the old-growth site influenced by artificial disturbance; the procedure revealed the pattern of change in the vegetation cover. Matrix model analysis showed that intensive use of plantations contributed to reduction of the area occupied by dwarf bamboo and pasture land (i.e., superior to simple abandonment). Furthermore, the field study of vegetation types and changes in species composition over 20 years suggests that plantations have contributed to a reduction in the effects of factors that inhibit revegetation. However, the establishment of monoculture plantations is frequently viewed skeptically as a procedure that is applied without fundamental ecological knowledge. For sustained management, adequate historical and ecological information on the restoration site should be provided to all stakeholders. An erratum to this article can be found at     

Quercus infectoria galls possess antioxidant activity and abrogates oxidative stress-induced functional alterations in murine macrophages

The present study reports the antioxidant activity of ethanolic extract of Quercus infectoria galls. The antioxidant potency of galls was investigated employing several established in vitro model systems. Their protective efficacy on oxidative modulation of murine macrophages was also explored. Gall extract was found to contain a large amount of polyphenols and possess a potent reducing power. HPTLC analysis of the extract suggested it to contain 19.925% tannic acid (TA) and 8.75% gallic acid (GA). The extract potently scavenged free radicals including DPPH (IC(50)~0.5 microg/ml), ABTS (IC(50)~1 microg/ml), hydrogen peroxide (H(2)O(2)) (IC(50)~2.6 microg/ml) and hydroxyl (*OH) radicals (IC(50)~6 microg/ml). Gall extract also chelated metal ions and inhibited Fe(3+) -ascorbate-induced oxidation of protein and peroxidation of lipids. Exposure of rat peritoneal macrophages to tertiary butyl hydroperoxide (tBOOH) induced oxidative stress in them and altered their phagocytic functions. These macrophages showed elevated secretion of lysosomal hydrolases, and attenuated phagocytosis and respiratory burst. Activity of macrophage mannose receptor (MR) also diminished following oxidant exposure. Pretreatment of macrophages with gall extract preserved antioxidant armory near to control values and significantly protected against all the investigated functional mutilations. MTT assay revealed gall extract to enhance percent survival of tBOOH exposed macrophages. These results indicate that Q. infectoria galls possess potent antioxidant activity, when tested both in chemical as well as biological models.     

Incorporating marginal covariate information in a nonparametric regression model for a sample of R x C tables

SUMMARY: Nonparametric regression models are proposed in the framework of ecological inference for exploratory modeling of disease prevalence rates adjusted for variables, such as age, ethnicity/race, and socio-economic status. Ecological inference is needed when a response variable and covariate are not available at the subject level because only summary statistics are available for the reporting unit, for example, in the form of R x C tables. In this article, only the marginal counts are assumed available in the sample of R x C contingency tables for modeling the joint distribution of counts. A general form for the ecological regression model is proposed, whereby certain covariates are included as a varying coefficient regression model, whereas others are included as a functional linear model. The nonparametric regression curves are modeled as splines fit by penalized weighted least squares. A data-driven selection of the smoothing parameter is proposed using the pointwise maximum squared bias computed from averaging kernels (explained by O'Sullivan, 1986, Statistical Science 1, 502-517). Analytic expressions for bias and variance are provided that could be used to study the rates of convergence of the estimators. Instead, this article focuses on demonstrating the utility of the estimators in a study of disparity in health outcomes by ethnicity/race.     

Comparing treatments in the presence of crossing survival curves: an application to bone marrow transplantation

Summary .   In some clinical studies comparing treatments in terms of their survival curves, researchers may anticipate that the survival curves will cross at some point, leading to interest in a long-term survival comparison. However, simple comparison of the survival curves at a fixed point may be inefficient, and use of a weighted log-rank test may be overly sensitive to early differences in survival. We formulate the problem as one of testing for differences in survival curves after a prespecified time point, and propose a variety of techniques for testing this hypothesis. We study these methods using simulation and illustrate them on a study comparing survival for autologous and allogeneic bone marrow transplants.     

Assemblage structure and conservation value of spiders and carabid beetles from restored lowland river banks

We assessed the composition of spider and carabid beetle assemblages along river banks from the Common Meuse (Belgium) to determine their relationships with local topographical and landscape-related characteristics. Data were gathered with pitfall traps in 1998 and explored by ordination and grouping methods. Our analysis revealed that the presence of xerothermic spider species was limited to scarcely covered, less dynamic gravel banks. Riparian spider species were found on frequently flooded as well as on rather elevated and high gravel banks, while riparian carabid beetles were dominant on all sampled banks. The level of flooding disturbance, the vegetation density and the presence of silt appeared to be the most important environmental determinants of spider and carabid beetle assemblage structure. Consequently, local environmental factors influence species occurrence patterns in a similar way for the two investigated arthropod groups. Nevertheless, distinct ecological groups are differently ordered along the prime environmental gradients. Nature management should therefore consider the conservation, restoration and connectivity of both dynamic and more elevated banks in order to obtain a high degree of local and regional heterogeneity throughout the river system.