Does a General Temperature-Dependent Q10 Model of Soil Respiration Exist at Biome and Global Scale?

Soil respiration (SR) is commonly modeled by a Q10 (an indicator of temperature sensitivity)function in ecosystem models. Q10is usually treated as a constant of 2 in these models, although Q10 value of SR often decreases with increasing temperatures. It remains unclear whether a general temperaturedependent Q10 model of SR exists at biome and global scale. In this paper, we have compiled the long-term Q10 data of 38 SR studies ranging from the Boreal, Temperate, to Tropical/Subtropical biome on four continents.Our analysis indicated that the general temperature-dependent biome Q10 models of SR existed, especially in the Boreal and Temperate biomes. A single-exponential model was better than a simple linear model in fitting the average Q10 values at the biome scale. Average soil temperature is a better predictor of Q10 value than average air temperature in these models, especially in the Boreal biome. Soil temperature alone could explain about 50% of the Q10 variations in both the Boreal and Temperate biome single-exponential Q10 model. Q10 value of SR decreased with increasing soil temperature but at quite different rates among the three biome Q10 models. The k values (Q10 decay rate constants) were 0.09, 0.07, and 0.02/℃ in the Boreal, Temperate, and Tropical/Subtropical biome, respectively, suggesting that Q10 value is the most sensitive to soil temperature change in the Boreal biome, the second in the Temperate biome, and the least sensitive in the Tropical/Subtropical biome. This also indirectly confirms that acclimation of SR in many soil warming experiments probably occurs. The k value in the "global" single-exponential Q10 model which combined both the Boreal and Temperate biome data set was 0.08/℃. However, the global general temperature-dependent Q10model developed using the data sets of the three biomes is not adequate for predicting Q10 values of SR globally.The existence of the general temperature-dependent Q10 models of SR in the Boreal and Temperate biome has important implications for modeling SR, especially in the Boreal biome. More detail model runs are needed to exactly evaluate the impact of using a fixed Q10 vs a temperature-dependent Q10 on SR estimate in ecosystem models (e.g., TEM, Biome-BGC, and PnET).     

Scientific publications about DNA structure-function and PCR technique in Costa Rica: a historic view (1953-2003)

The spreading of knowledge depends on the access to the information and its immediate use. Models are useful to explain specific phenomena. The scientific community accepts some models in Biology after a period of time, once it has evidence to support it. The model of the structure and function of the DNA proposed by Watson & Crick (1953) was not the exception, since a few years later the DNA model was finally accepted. In Costa Rica, DNA function was first mentioned in 1970, in the magazine Biologia Tropical (Tropical Biology Magazine), more than 15 years after its first publication in a scientific journal. An opposite situation occurs with technical innovations. If the efficiency of a new scientific technique is proved in a compelling way, then the acceptance by the community comes swiftly. This was the case of the polymerase chain reaction, or PCR. The first PCR machine in Costa Rica arrived in 1991, only three years after its publication.     

Does a General Temperature-Dependent Q10 Model of Soil Respiration Exist at Biome and Global Scale？

Soil respiration （SR） is commonly modeled by a Q10 （an indicator of temperature sensitivity） function in ecosystem models. Q10 is usually treated as a constant of 2 in these models, although Q10 value of SR often decreases with increasing temperatures. It remains unclear whether a general temperature- dependent Q10 model of SR exists at biome and global scale. In this paper, we have compiled the long-term Q10 data of 38 SR studies ranging from the Boreal, Temperate, to Tropical/Sublropical biome on four continents. Our analysis indicated that the general temperature-dependent biome Q10 models of SR existed, especially in the Boreal and Temperate biomes. A single-exponential model was better than a simple linear model in fitting the average Q10 values at the biome scale. Average soil temperature is a better predictor of Q10 value than average air temperature in these models, especially in the Boreal biome. Soil temperature alone could explain about 50% of the Q10 variations in both the Boreal and Temperate biome single-exponential Q10 model. Q10 value of SR decreased with increasing soil temperature but at quite different rates among the three biome Q10 models. The k values （Q10 decay rate constants） were 0.09, 0.07, and 0.02/℃ in the Boreal, Temperate, and Tropical/Subtropical biome, respectively, suggesting that Q10 value is the most sensitive to soil temperature change in the Boreal biome, the second in the Temperate biome, and the least sensitive in the Tropical/ Subtropical biome. This also indirectly confirms that acclimation of SR in many soil warming experiments probably occurs. The k value in the ＂global＂ single-exponential Q10 model which combined both the Boreal and Temperate biome data set was 0.08/℃. However, the global general temperature-dependent Q10 model developed using the data sets of the three biomes is not adequate for predicting Q10 values of SR globally. The existence of the general temperature-dependent Q10 models of SR in the Boreal and Temperate biome has important implications for modeling SR, especially in the Boreal biome. More detail model runs are needed to exactly evaluate the impact of using a fixed Q10 vs a temperature-dependent Q10 on SR estimate in ecosystem models （e.g., TEM, Biome-BGC, and PnET）.     

Rethinking tropical ecosystem management

Tropical Environments: The Functioning and Management of Tropical Ecosystems by M. Kellman and R. Tackaberry Routledge, 1997. ￡60.00 hbk, ￡18.99 pbk (xix+380 pages) ISBN 0 415 11608 2/0 415 11609 0.     

The land–atmosphere water flux in the tropics

Tropical vegetation is a major source of global land surface evapotranspiration, and can thus play a major role in global hydrological cycles and global atmospheric circulation. Accurate prediction of tropical evapotranspiration is critical to our understanding of these processes under changing climate. We examined the controls on evapotranspiration in tropical vegetation at 21 pan-tropical eddy covariance sites, conducted a comprehensive and systematic evaluation of 13 evapotranspiration models at these sites, and assessed the ability to scale up model estimates of evapotranspiration for the test region of Amazonia. Net radiation was the strongest determinant of evapotranspiration (mean evaporative fraction was 0.72) and explained 87% of the variance in monthly evapotranspiration across the sites. Vapor pressure deficit was the strongest residual predictor (14%), followed by normalized difference vegetation index (9%), precipitation (6%) and wind speed (4%). The radiation-based evapotranspiration models performed best overall for three reasons: (1) the vegetation was largely decoupled from atmospheric turbulent transfer (calculated from Ω decoupling factor), especially at the wetter sites; (2) the resistance-based models were hindered by difficulty in consistently characterizing canopy (and stomatal) resistance in the highly diverse vegetation; (3) the temperature-based models inadequately captured the variability in tropical evapotranspiration. We evaluated the potential to predict regional evapotranspiration for one test region: Amazonia. We estimated an Amazonia-wide evapotranspiration of 1370 mm yr⁻¹, but this value is dependent on assumptions about energy balance closure for the tropical eddy covariance sites; a lower value (1096 mm yr⁻¹) is considered in discussion on the use of flux data to validate and interpolate models.     

楝科（Meliaceae）的地理分布

楝科为泛热带分布科,全世界有５１属,约５５０—６００种,分布于旧世界热带地区有４６属,热带美洲有８属．热带亚洲和热带非洲为楝科两大现代分布中心．中国楝科共１５属,６１种,占世界属总数的２９％,种总数的１０％。中国楝科的分布是在全球楝科分布区的边缘,主要分布于中国西南部及南部诸省,种类由西南向东南递减。中国楝科属的分布区类型可归为５类：１．热带亚洲、非洲和中南美洲间断分布（１属）;２．旧世界热带分布（３属）;３,热带亚洲至热带大洋洲分布（２属）;４．热带亚洲至热带非洲分布（１属）;５．热带亚洲分布（８属）。中国楝科种的分布区类型仅有２类：１．热带亚洲分布（３１种）;２．中国特有分布（３０种）。楝科植物的起源推断在早白垩纪。中国楝科植物由印度—马来西亚成分及特有成分组成。热带亚洲的楝科植物主要是通过中南半岛和中国云南。广西和海南等地发生联系,而菲律宾和台湾之间可有直接的联系。     

中国38个地区兰科植物区系成分的比较分析

通过对中国38个地区共147属,984种兰科植物的区系成分的统计,分析了各地区兰科植物的属种热带成分/温带成分(R/T)值随纬度的变化趋势;并利用SPSS 20.0软件对各地区兰科植物的区系成分进行聚类分析。结果表明:(1)38个地区147属兰科植物可划分为11种分布区类型和9种变型,984种兰科植物可划分为12种分布区类型和6种变型。(2)属级水平上R/T值随纬度的升高总体呈下降趋势,38个地区中23个地区为热带性质,13个地区为温带性质,峨眉山和金佛山的热带性质和温带性质相等;种级水平上除俄贤岭的特殊岛屿石灰岩环境造成极强的热带性质外,其他地区的R/T值随纬度的升高而降低,表现出明显的纬向地带性特点。(3)38个地区兰科植物属种级区系类型存在分异现象,即147属兰科植物以热带亚洲分布(24.71%)、北温带分布(19.14%)和热带亚洲至热带大洋洲分布(15.32%)为主,而984种兰科植物除热带亚洲分布(30.28%)外,则以中国特有分布(26.89%)和中国-日本分布(12.85%)为主。(4)属种级聚类结果显示,种级水平的聚类分析比属级水平的聚类更能体现出纬度相近其区系成分也相近的特点。     

Spatial diversity patterns of Pristimantis frogs in the Tropical Andes

Although biodiversity gradients have been widely documented, the factors governing broad‐scale patterns in species richness are still a source of intense debate and interest in ecology, evolution, and conservation biology. Here, we tested whether spatial hypotheses (species–area effect, topographic heterogeneity, mid‐domain null model, and latitudinal effect) explain the pattern of diversity observed along the altitudinal gradient of Andean rain frogs of the genus Pristimantis. We compiled a gamma‐diversity database of 378 species of Pristimantis from the tropical Andes, specifically from Colombia to Bolivia, using records collected above 500 m.a.s.l. Analyses were performed at three spatial levels: Tropical Andes as a whole, split in its two main domains (Northern and Central Andes), and split in its 11 main mountain ranges. Species richness, area, and topographic heterogeneity were calculated for each 500‐m‐width elevational band. Spatial hypotheses were tested using linear regression models. We examined the fit of the observed diversity to the mid‐domain hypothesis using randomizations. The species richness of Pristimantis showed a hump‐shaped pattern across most of the altitudinal gradients of the Tropical Andes. There was high variability in the relationship between area and species richness along the Tropical Andes. Correcting for area effects had little impact in the shape of the empirical pattern of biodiversity curves. Mid‐domain models produced similar gradients in species richness relative to empirical gradients, but the fit varied among mountain ranges. The effect of topographic heterogeneity on species richness varied among mountain ranges. There was a significant negative relationship between latitude and species richness. Our findings suggest that spatial processes partially explain the richness patterns of Pristimantis frogs along the Tropical Andes. Explaining the current patterns of biodiversity in this hot spot may require further studies on other possible underlying mechanisms (e.g., historical, biotic, or climatic hypotheses) to elucidate the factors that limit the ranges of species along this elevational gradient.     

External morphology of Lagenidium giganteum zoospores (Oomycetes: Lagenidiales)

The external morphology of Lagenidium giganteum was studied with the aid of Nomarski differential interference microscopy, scanning electron microscopy and unidirectional shadow-casting techniques. Zoospores were ovoid, bluntly pointed and flattered on one side at the anterior end. On one side of the zoospore, a groove ran from end to end parallel to the long axis. Protruding from the groove were two flagella, a posterior whiplike flagellum and an anterior tinsel flagellum with lateral hair. Features of the zoospore surface included an irregular reticulate pattern of ridges and mounds marked by deep irregular pits scattered randomly over the zoospore surface.This investigation received financial support from UNDP/World bank/WHO Special Programme for research and training in Tropical Diseases under the Scientific Working Group on Biological Control of Vectors.Rhode Island Agricultural Experiment Station Contribution N 2287.     

Amyloid formation in response to beta cell stress occurs in vitro, but not in vivo, in islets of transgenic mice expressing human islet amyloid polypeptide.

BACKGROUND: Human, but not mouse, islet amyloid polypeptide (IAPP) is amyloidogenic. Transgenic mice overexpressing human IAPP in the beta cells of the islets of Langerhans should be useful in identifying factors important for the deposition of IAPP as insoluble amyloid fibrils. MATERIALS AND METHODS: Transgenic mice expressing human IAPP were examined using several experimental models for the production of persistent hyperglycemia, as well as for the overstimulation and/or inhibition of beta cell secretion. Obesity was induced by aurothioglucose. Persistent hyperglycemia was produced by long-term administration of glucocorticosteroids or by partial pancreatectomy. Inhibition of normal beta cell exocytosis by diazoxide administration, with or without concurrent dexamethasone injections, was carried out to increase crinophagy of secretory granules. The human IAPP gene was also introduced into the ab and ob mouse models for diabetes. Finally, isolated islets cultivated in vitro at high glucose concentration were also examined. RESULTS: No amyloid deposits were found in the pancreata of any of the animals, either by light microscopy after Congo red staining or by electron microscopy after immunogold labeling with antibodies specific for human IAPP. Aurothioglucose treatment resulted in increased numbers of granules in the beta cell and the appearance of large lysosomal bodies without amyloid. However, islets from db and ob mice expressing human IAPP cultivated in vitro in the presence of glucocorticosteroid and/or growth hormone, were found to contain extracellular amyloid deposits reacting with antibodies to human IAPP. CONCLUSIONS: Oversecretion of human IAPP or increased crinophagy are not sufficient for amyloid formation. This indicates that other factors must influence amyloid deposition; one such factor may be the local clearance of IAPP.     

Call to consolidate achievements for onchocerciasis and lymphatic filariasis control

The Bernhard Nocht Institute for Tropical Medicine and the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases held an international conference to review recent achievements in research and control of onchocerciasis and lymphatic filariasis on 19-23 September 2001 in Hamburg, Germany.     

Morphological variation of henequen (Agave fourcroydes, Agavaceae) germplasm and its wild ancestor (A. angustifolia) under uniform growth conditions: diversity and domestication

Extant variants of henequen (Agave fourcroydes Lem.) and wild populations of its putative ancestor A. angustifolia Haw. were grown in the Mexican state of Yucatan for 10 yr under homogeneous conditions. A statistical and numerical analysis of their patterns of morphological variation was performed as part of broader research to provide evidence of its genetic diversity, evolutionary relationships and changes under human selection. A comparison with results of a similar analysis under natural growing conditions was also made. The study indicated the following. (1) Under natural growth conditions, the three putative wild ecotypes are morphologically distinct, but under uniform conditions only populations growing in Tropical subdeciduous forest may be distinguished from the other two, thus indicating the probable existence of only two ecotypes: one growing in Coastal dunes and Tropical subdeciduous forest, and the other growing in Tropical deciduous forest. (2) This last ecotype is the most similar to cultivated variants. Within its populations, the most similar to the cultivated is that known as Chelem White, gathered by artisans for its textile use. (3) The cordage-cultivated Sac Ki and Yaax Ki differ from wild populations in four syndromes of domestication: gigantism, greater fibrosity, less thorniness, and less reproductive capacity. The lower cv of their characteristics compared with those of wild populations suggest less genetic diversity. (4) Kitam Ki is probably a textile-cultivated variant of recent introduction and/or a variant in which the artificial selection process has had different direction and intensity. (5) Improved growth conditions in the botanic garden resulted in a decreased cv, an increase in size and fiber content, and a reduction of thorniness for both wild and cultivated variants. Given that wild populations with desirable characteristics exist and that these characteristics are highly plastic and respond positively to cultivation, then selection and cultivation of populations such as those from Tropical deciduous forest may well have been the path taken by the ancient Maya during henequen domestication.     

Systematic conservation assessment for the Mesoamerica, Chocó, and Tropical Andes biodiversity hotspots: a preliminary analysis

Using IUCN Red List species as biodiversity surrogates, supplemented with additional analyses based on ecoregional diversity, priority areas for conservation in Mesoamerica, Chocó, and the Tropical Andes were identified using the methods of systematic conservation planning. Species’ ecological niches were modeled from occurrence records using a maximum entropy algorithm. Niche models for 78 species were refined to produce geographical distributions. Areas were prioritized for conservation attention using a complementarity-based algorithm implemented in the ResNet software package. Targets of representation for Red List species were explored from 10 to 90% of the modeled distributions at 10% increments; for the 53 ecoregions, the target was 10% for each ecoregion. Selected areas were widely dispersed across the region, reflecting the widespread distribution of Red List species in Mesoamerica, Chocó, and the Tropical Andes, which underscores the region’s importance for biodiversity. In general, existing protected areas were no more representative of biodiversity than areas outside them. Among the countries in the region, the protected areas of Belize performed best and those of Colombia and Ecuador worst. A high representation target led to the selection of a very large proportion of each country except Colombia and Ecuador (for a 90% target, 83–95% of each country was selected). Since such large proportions of land cannot realistically be set aside as parks or reserves, biodiversity conservation in Mesoamerica, Chocó, and the Tropical Andes will require integrative landscape management which combines human use of the land with securing the persistence of biota. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Chyluria with proteinuria or filarial nephropathy? An enigma

Lymphatic filariasis is endemic in India. Out of 128 million infected individuals worldwide, India accounts for 48 million cases [Manson's Tropical Diseases, 21st Ed. p 1488]. Filariasis can have protean manifestations, but Tropical pulmonary eosinophilia and chyluria are unusual manifestations reported mainly from South Asian countries [Manson's Tropical Diseases, 21st Ed. p 1494]. Chyluria occurs only in 2% of filarial afflicted patients in the filarial belt [Diamond E, Schapira HE. Chyluria--a review of literature. Urology 1985;26(5): 427-31]. Lymphatic filariasis presenting as chyluria may be equally rare. Predominant chyluria with no overt lymphatic filariasis remains an enigma.     

Patent pools and clearinghouses in the life sciences

The biopharmaceutical industry is slowly absorbing the idea of collaborative patent licensing models. Recently, two patent pools for developing countries have been launched: the Pool for Open Innovation against Neglected Tropical Diseases initiated by GlaxoSmithKline (GSK), which is referred to as the BIO Ventures for Global Health (BVGH) pool, and the Medicines Patent Pool (MPP) initiated by UNITAID. Various organizations have recommended using pools or clearinghouses beyond the humanitarian dimension where many patents are owned by many different actors. As a first attempt, MPEG LA, which administers patent pools in various technology fields, is now setting up a clearinghouse for patents related to molecular diagnostics. These examples as well as the results from an empirical study provide useful insights for the design and administration of future pools and clearinghouses in the life sciences.     

中国海南岛灵芝资源及其分布特征*

本文报道了海南岛的灵芝科真菌７８种,分属于４个属,３个亚属,２个组。分析了灵芝在不同的热带植被类型中,其种类的组成不同。种类多样性变化呈：常绿季雨林＞热带雨林＞低山雨林＞中山雨林＞热带半落叶季雨林＞人工林＞河谷雨林＞稀树草原＞山顶矮林＞红树林的趋势     

The sensitivity of tree growth to air mass variability and the Pacific Decadal Oscillation in coastal Alabama

This study investigates the relationship between tree growth and air mass type variability, using the spatial synoptic classification (SSC) in a bottomland slash pine forest in coastal Alabama (USA). The use of an air mass approach in dendroclimatology is somewhat unconventional and has not been fully explored. However, we believe that it may be useful because the air mass approach represents a holistic and comprehensive measure of surface conditions. Cores from 36 slash pines (Pinus elliotti) were extracted and ring widths were measured to the nearest 0.01 mm. The cores were then cross-dated and a standardized ring index series was established. Relationships were explored between the index series and several climate variables and teleconnections. The index series showed significant relationships with SSC air mass types and SSC air mass ratios, but insignificant results with teleconnections. Specifically the Dry Tropical air mass type was negatively correlated with tree growth while Moist Moderate was positively correlated. Concomitantly, Dry Tropical : Moist Moderate, Dry Tropical : Moist Tropical, and Dry Moderate : Moist Moderate air mass ratios also showed negative correlations. Positive Pacific Decadal Oscillation (PDO) sea surface temperatures were also associated with significant moisture and air mass variability in the region, although the PDO did not have a significant relationship with tree growth. The significance between SSC air mass variability and tree growth in the humid subtropical climate of coastal Alabama has favorable implications for dendroclimatological research in drier environments where trees are more sensitive to climatic variables.     

Bacterial rhodopsins: evolution of a mechanistic model for the ion pumps

Walther Stoeckenius received a MD degree at the University of Hamburg, Germany in 1950. After 18 months of clinical work as an intern, he began postdoctoral work on the development of pox viruses at the Institute for Tropical Medicine in Hamburg using mainly electron microscopy techniques. After two years he moved as Assistant Professor to the Department of Pathology at the University of Hamburg and became Docent for Pathology in 1958. In addition to teaching and routine pathology work, he continued to use electron microscopy to explore the fine structure of cells and developed an interpretation of the triple-layered appearance of membranes in electron micrographs in terms of molecular structure and the chemistry of osmium tetroxide fixation. In 1959 he obtained a position as Research Associate in Keith Porter's laboratory at Rockefeller University. This was changed after a few months to Assistant Professor and he stayed there, later as Associate Professor, for eight years. The work on membrane structure continued, and a model was developed that described the membrane as a lipid bilayer with embedded protein domains. In efforts to isolate such domains, the purple membrane and bacteriorhodopsin were discovered. In 1966, the lure of California became irresistible and Dr. Stoeckenius accepted a professorship at the University of California at San Francisco. The work on bacteriorhodopsin continued there with the emphasis changing from electron microscopy to spectroscopy and biochemical techniques. He is now Professor Emeritus there in the Department of Biochemistry and Biophysics and the Cardiovascular Research Institute.     

The Tropical Biominer Project: mining old sources for new drugs

The Tropical Biominer Project is a recent initiative from the Federal University of Minas Gerais (UFMG) and the Oswaldo Cruz foundation, with the participation of the Biominas Foundation (Belo Horizonte, Minas Gerais, Brazil) and the start-up Homologix. The main objective of the project is to build a new resource for the chemogenomics research, on chemical compounds, with a strong emphasis on natural molecules. Adopted technologies include the search of information from structured, semi-structured, and non-structured documents (the last two from the web) and datamining tools in order to gather information from different sources. The database is the support for developing applications to find new potential treatments for parasitic infections by using virtual screening tools. We present here the midpoint of the project: the conception and implementation of the Tropical Biominer Database. This is a Federated Database designed to store data from different resources. Connected to the database, a web crawler is able to gather information from distinct, patented web sites and store them after automatic classification using datamining tools. Finally, we demonstrate the interest of the approach, by formulating new hypotheses on specific targets of a natural compound, violacein, using inferences from a Virtual Screening procedure.