Human Populations (human + population)

Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Human Populations

  • growing human population
  • modern human population
  • past human population
  • world human population

  • Terms modified by Human Populations

  • human population density
  • human population growth

  • Selected Abstracts


    Linkage Disequilibrium Mapping of Disease Susceptibility Genes in Human Populations

    INTERNATIONAL STATISTICAL REVIEW, Issue 1 2000
    David Clayton
    Summary The paper reviews recent work on statistical methods for using linkage disequilibrium to locate disease susceptibility genes, given a set of marker genes at known positions in the genome. The paper starts by considering a simple deterministic model for linkage disequilibrium and discusses recent attempts to elaborate it to include the effects of stochastic influences, of "drift", by the use of either Writht-Fisher models or by approaches based on the coalescence of the genealogy of the sample of disease chromosomes. Most of this first part of the paper concerns a series of diallelic markers and, in this case, the models so far proposed are hierarchical probability models for multivariate binary data. Likelihoods are intractable and most approaches to linkage disequilibrium mapping amount to marginal models for pairwise associations between individual markers and the disease susceptibility locus. Approaches to evalutation of a full likelihood require Monte Carlo methods in order to integrate over the large number of unknowns. The fact that the initial state of the stochastic process which has led to present-day allele frequencies is unknown is noted and its implications for the hierarchical probability model is discussed. Difficulties and opportunities arising as a result of more polymorphic markers and extended marker haplotypes are indicated. Connections between the hierarchical modelling approach and methods based upon identity by descent and haplotype sharing by seemingly unrelated case are explored. Finally problems resulting from unknown modes of inheritance, incomplete penetrance, and "phenocopies" are briefly reviewed. Résumé Ce papier est une revue des travaux récents, protant sur les méthodes statistiques qui utilisent I'étude, des liaisons désé, quilib rées, pour identifer les génes, de susceptibilité des maladies,ápartir d'une série, de marqueurs de géncs á des positions définies du génome,. Le papier commence par considérer, un modéle, détéministe, simple pour liaisons déséquilibr,ées, puis nous discutons les améliorations, ré centes proposées, de ce modéle, dans but de tenir compte des effects des influences stochastiques soit en utilisant les modéles, de wright-fisher, soit par des approches basées, sur la coalescence de la géné alogic de I'échantillon, des chromosomes malades. La plupart de cette premiére, partie porte sur une série, de marqueurs dialléliques et, dans ce cas, les modéles, proposés, sont des modéles, hiérerchiques, probabilistes pour dinnées, binaires multivariées. Les viaisemblances n'ont pas de forme analytique et la plupart des approches pour la cartographie des liaisons déséquilibrées, sont équivalentes aux modéles, marginaux pour dinnées, appariées, entre des marqueurs individuels et le géne, de susceptibilité de la maladie.Pour évaluer, la vriausemblance compléte, des méthodes de Monte carlo sont nécessaires, afin d'intégrer, le large nombre d; inconnues. Le fait que l'état, initial du process stochastique qui a conduit éla fré, quence, allélique, actuel soit inconnu est á noter et ses implications pour le modéle, hiérarchique, probabiliste sont discutées.Les difficultés, et implications issues de marqueurs polumorphiques et de marquers haplotypes sont dévéloppées.Les liens entire l'approche de modélisation, hiérerchique, et les méthodes, d'analyse d'identite pardescendance et les haplotypes partagés, par des cas apparement non apparentés, sont explorés. Enfin les problémes, relatifs à des modes de transmission inconnus,à des pénétrances, incomplé, tes, et aux "phénocopies" sont briévenment evoqués. [source]


    Is There a Stabilizing Selection Around Average Fertility in Modern Human Populations?

    POPULATION AND DEVELOPMENT REVIEW, Issue 3 2001
    Ulrich Mueller
    Possibly the greatest challenge for an evolutionary explanation of demographic transition is the fact that fertility levels universally start to fall first among the well-to-do, well-educated, healthy classes, which can be explained only by some voluntary or at least adaptive action. The problem of how restraints on fertility could have evolved by natural selection has been tackled with group selection models as well as with stabilizing selection models. The latter model, which is critically discussed in this article, posits that some intermediate (rather than maximal) level of fertility is optimal for long-term reproductive success. Tests of stabilizing selection in human populations are rare, their results inconclusive. Here four sets of data are analyzed: they are samples drawn from the 'class of 1950 of the US Military Academy at West Point (cohorts 1923,29), retired US noncommissioned officers (cohorts 1913,37), and western German and eastern German physicians (cohorts 1930,35), all containing fertility data over two generations, and from European royalty (cohorts 1790,1939) containing fertility data over four generations. Deterministic as well as stochastic fitness measures are used. It is found that maximal, not average, fertility in the first generation leads to maximal long-term reproductive success. Also against prediction, no decreasing marginal fitness gains by increasing fertility can be observed. The findings leave little space for considering stabilizing selection as a plausible mechanism explaining the course of demographic transition but indicate instead that biological evolution today is as fast and vigorous as ever in human history. Even in large populations, all people living today may be the descendants of just some few percents,a much smaller proportion than generally believed, of the people living some generations ago. [source]


    Estimation and evidence in forensic anthropology: Sex and race

    AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009
    Lyle W. Konigsberg
    Abstract Forensic anthropology typically uses osteological and/or dental data either to estimate characteristics of unidentified individuals or to serve as evidence in cases where there is a putative identification. In the estimation context, the problem is to describe aspects of an individual that may lead to their eventual identification, whereas in the evidentiary context, the problem is to provide the relative support for the identification. In either context, individual characteristics such as sex and race may be useful. Using a previously published forensic case (Steadman et al. (2006) Am J Phys Anthropol 131:15,26) and a large (N = 3,167) reference sample, we show that the sex of the individual can be reliably estimated using a small set of 11 craniometric variables. The likelihood ratio from sex (assuming a 1:1 sex ratio for the "population at large") is, however, relatively uninformative in "making" the identification. Similarly, the known "race" of the individual is relatively uninformative in "making" the identification, because the individual was recovered from an area where the 2000 US census provides a very homogenous picture of (self-identified) race. Of interest in this analysis is the fact that the individual, who was recovered from Eastern Iowa, classifies very clearly with [Howells 1973. Cranial Variation in Man: A Study by Multivariate Analysis of Patterns of Difference Among Recent Human Populations. Cambridge, MA: Peabody Museum of Archaeology and Ethnology; 1989. Skull Shape and the Map: Craniometric Analyses in the Dispersion of Modern Homo. Cambridge, MA: Harvard University Press]. Easter Islander sample in an analysis with uninformative priors. When the Iowa 2000 Census data on self-reported race are used for informative priors, the individual is clearly identified as "American White." This analysis shows the extreme importance of an informative prior in any forensic application. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source]


    Book review: The Evolution and History of Human Populations in South Asia

    AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2008
    Andrew Kramer
    No abstract is available for this article. [source]


    Different Evolutionary Histories of the Coagulation Factor VII Gene in Human Populations?

    ANNALS OF HUMAN GENETICS, Issue 1 2010
    Georgios Athanasiadis
    Summary Immoderate blood clotting constitutes a risk factor for cardiovascular disease in modern industrialised societies, but is believed to have conferred a survival advantage, i.e. faster recovery from bleeding, on our ancestors. Here, we investigate the evolutionary history of the Coagulation Factor VII gene (F7) by analysing five cardiovascular-risk-associated mutations from the F7 promoter and nine neutral polymorphisms (six SNPs and three microsatellites) from the flanking region in 16 populations from the broader Mediterranean region, South Saharan Africa and Bolivia (687 individuals in total). Population differentiation and selection tests were performed and linkage disequilibrium patterns were investigated. In all samples, no linkage disequilibrium between adjacent F7 promoter mutations ,402 and ,401 was observed. No selection signals were detected in any of the samples from the broader Mediterranean region and South Saharan Africa, while some of the data suggested a potential signal of positive selection for the F7 promoter in the Native American samples from Bolivia. In conclusion, our data suggest, although do not prove, different evolutionary histories in the F7 promoter region between Mediterraneans and Amerindians. [source]


    Study of Regions of Extended Homozygosity Provides a Powerful Method to Explore Haplotype Structure of Human Populations

    ANNALS OF HUMAN GENETICS, Issue 2 2008
    D. Curtis
    Summary Previous investigations have reported linkage disequilibrium occurring between nearby polymorphisms, a block-like structure for such relationships, some instances where surprisingly few haplotypes are found and regions of extended homozygosity which are especially marked around centromeres and which are especially common on the X chromosome. We investigated the distribution and nature of regions of extended homozygosity in a sample of 1411 subjects included in a genome wide association study. Regions of extended homozygosity over 1Mb are common, with an average of 35.9 occurring per subject, and containing on average 73 homozygous markers. They have a markedly non-random distribution. They are relatively common on the X chromosome and are seen at centromeres but are also concentrated at other chromosomal regions where presumably recombination is rare. They seem to be a consequence of some haplotypes being very common in the population and although sometimes this reflects the effect of a very common haplotype we also note that there are examples of two or three common haplotypes, each very different from each other, underlying this effect. Regions of extended homozygosity are commoner than previously appreciated. They result from the presence of extended haplotypes with high population frequency. Such regions concentrate in particular locations. The haplotypes involved are sometimes markedly disparate from each other. These regions offer a valuable opportunity for further investigation, in particular with regard to their ancestral history. [source]


    The relative role of drift and selection in shaping the human skull

    AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010
    Lia Betti
    Abstract Human populations across the world vary greatly in cranial morphology. It is highly debated to what extent this variability has accumulated through neutral processes (genetic drift) or through natural selection driven by climate. By taking advantage of recent work showing that geographic distance along landmasses is an excellent proxy for neutral genetic differentiation, we quantify the relative role of drift versus selection in an exceptionally large dataset of human skulls. We show that neutral processes have been much more important than climate in shaping the human cranium. We further demonstrate that a large proportion of the signal for natural selection comes from populations from extremely cold regions. More generally, we show that, if drift is not explicitly accounted for, the effect of natural selection can be greatly overestimated. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source]


    Conservation Biology in Asia: the Major Policy Challenges

    CONSERVATION BIOLOGY, Issue 4 2009
    JEFFREY A. McNEELY
    Asia; bosques; comercio de vida silvestres; conflicto humano-animal; economía Abstract:,With about half the world's human population and booming economies, Asia faces numerous challenges to its biodiversity. The Asia Section of the Society for Conservation Biology has identified some key policy issues in which significant progress can be made. These include developing new sources of funding for forest conservation; identifying potential impacts of energy alternatives on the conservation of biodiversity; curbing the trade in endangered species of plants and animals; a special focus on the conservation of mountain biodiversity; enhancing relevant research; ensuring that conservation biology contributes to major international conventions and funding mechanisms; using conservation biology to build a better understanding of zoonotic diseases; more effectively addressing human,animal conflicts; enhancing community-based conservation; and using conservation biology to help address the pervasive water-deficit problems in much of Asia. These challenges can be met through improved regional cooperation among the relevant stakeholders. Resumen:,Con aproximadamente la mitad de la población humana y economías prósperas, Asia enfrenta numerosos retos para su biodiversidad. La sección Asia de la Sociedad para la Biología de la Conservación ha identificado algunos temas políticos claves en los que se puede hacer un progreso significativo. Estos incluyen el desarrollo de nuevas fuentes de financiamiento para la conservación de bosques; la identificación de impactos potenciales de las energías alternativas sobre la conservación de la biodiversidad; reducción del comercio de especies de animales y plantas en peligro; un enfoque especial en la conservación de la biodiversidad montana; promoción de investigación relevante; garantía de que la biología de la conservación contribuye a convenios internacionales y mecanismos de financiamiento; utilización de la biología de la conservación para lograr un mejor entendimiento de enfermedades zoonóticas; mejor atención a los conflictos humanos-animales; reforzamiento de la conservación basada en comunidades y utilización de la biología de la conservación para atender los problemas de déficit de agua en gran parte de Asia. Estos retos se pueden atender mediante una mejor cooperación regional entre los principales actores. [source]


    Bushmeat Markets on Bioko Island as a Measure of Hunting Pressure

    CONSERVATION BIOLOGY, Issue 6 2000
    John E. Fa
    Comparisons of the availability and abundance of individual species between years showed that more species and more carcasses appeared in 1996 than in 1991. In biomass terms, the increase was significantly less, only 12.5%, when compared with almost 60% more carcasses entering the market in 1996. A larger number of carcasses of the smaller-bodied species (i.e., rodents and the blue duiker [Cephalophus monticola] ) were recorded in 1996 than in 1991. Although an additional four species of birds and one squirrel were recorded in 1996, these were less important in terms of their contribution to biomass or carcass numbers. Concurrently, there was a dramatic reduction in the larger-bodied species, Ogilby's duiker (C. ogilbyi) and seven diurnal primates. We examined these changes, especially the drop in the number of larger animals. We considered the possible following explanations: (1) the number of hunters dropped either because of enforced legislation or scarcity of larger prey; (2) a shift in the use of hunting techniques occurred ( from shotguns to snares); or (3) consumer demand for primate and duiker meat dropped, which increased demand for smaller game. Our results suggest that the situation in Bioko may be alarmingly close to a catastrophe in which primate populations of international conservation significance are being hunted to dangerously low numbers. Although there is still a need for surveys of actual densities of prey populations throughout the island, working with the human population on Bioko to find alternatives to bushmeat is an urgent priority. Resumen: Realizamos conteos de los cuerpos de animales llevados al mercado de Malabo, en la Isla Bioko, Guinea Ecuatorial, durante dos periodos de estudio de ocho meses cada uno en 1991 y 1996. Las comparaciones realizadas de la disponibilidad y abundancia de especies individuales entre estos años mostró que más especies y más cuerpos aparecieron en 1996 que en 1991. En términos de biomasa, el incremento fue significativamente menor, solo 12.5% cuando se comparó con un incremento de casi un 60% más de cuerpos que llegaron al mercado en 1996. Se observó un mayor número de cuerpos de especies de tamaño pequeño ( por ejemplo roedores, y el duiker azul, Cephalophus monticola) en 1996 que en 1991. A pesar de que hubo una adición de cuatro especies de aves y una especie de ardilla en 1996, estas fueron menos importantes en cuanto a su contribución a la biomasa o el número de cuerpos. Al mismo tiempo, hubo una reducción dramática de especies de cuerpo grande, el duiker de Ogilby (C. ogilbyi) y siete primates diurnos. Examinamos estos cambios, especialmente la caída en el número de animales grandes y consideramos las siguientes posibles explicaciones: (1) hubo una caída significativa en el número de cazadores debido a la posible ejecución de la legislación o debido a una escasez de presas grandes; (2) hubo un cambio en el uso de técnicas de caza ( por ejemplo, el reemplazo de armas de fuego por trampas); o (3) la demanda del consumidor por carne de primates y duikers disminuyó, incrementándose la demanda por animales pequeños. Nuestros resultados sugieren que la situación en Bioko puede estar alarmantemente cerca de una catástrofe en la cual las poblaciones de primates, que son de gran significado para la conservación internacional, han sido reducidas a niveles peligrosamente bajos. A pesar de que aún se necesita llevar a cabo estudios de las densidades existentes de poblaciones de presas a lo largo de la isla, es urgente trabajar con la población humana de Bioko para encontrar alternativas a la venta de carne silvestre. [source]


    Filariasis: diagnosis and treatment

    DERMATOLOGIC THERAPY, Issue 6 2009
    Natalia Mendoza
    ABSTRACT Filariasis is an infectious disease of the lymphatics and subcutaneous tissues caused by nematodes or filariae. Carried by mosquito vectors, this disease causes millions of people to suffer from lymphedema and elephantiasis, characteristics of filariasis infection. This disease can be diagnosed through the identification of microfilariae in blood or skin samples, antigen detection, radiographic imaging, or polymerase chain reaction. Mass drug administration by the World Health Organization has helped to diminish the incidence of filariasis. However, continued research on new drugs and vaccinations will be needed to control and reduce the microfilarial levels in the human population. [source]


    Range-wide patterns of greater sage-grouse persistence

    DIVERSITY AND DISTRIBUTIONS, Issue 6 2008
    Cameron L. Aldridge
    ABSTRACT Aim, Greater sage-grouse (Centrocercus urophasianus), a shrub-steppe obligate species of western North America, currently occupies only half its historical range. Here we examine how broad-scale, long-term trends in landscape condition have affected range contraction. Location, Sagebrush biome of the western USA. Methods, Logistic regression was used to assess persistence and extirpation of greater sage-grouse range based on landscape conditions measured by human population (density and population change), vegetation (percentage of sagebrush habitat), roads (density of and distance to roads), agriculture (cropland, farmland and cattle density), climate (number of severe and extreme droughts) and range periphery. Model predictions were used to identify areas where future extirpations can be expected, while also explaining possible causes of past extirpations. Results, Greater sage-grouse persistence and extirpation were significantly related to sagebrush habitat, cultivated cropland, human population density in 1950, prevalence of severe droughts and historical range periphery. Extirpation of sage-grouse was most likely in areas having at least four persons per square kilometre in 1950, 25% cultivated cropland in 2002 or the presence of three or more severe droughts per decade. In contrast, persistence of sage-grouse was expected when at least 30 km from historical range edge and in habitats containing at least 25% sagebrush cover within 30 km. Extirpation was most often explained (35%) by the combined effects of peripherality (within 30 km of range edge) and lack of sagebrush cover (less than 25% within 30 km). Based on patterns of prior extirpation and model predictions, we predict that 29% of remaining range may be at risk. Main Conclusions, Spatial patterns in greater sage-grouse range contraction can be explained by widely available landscape variables that describe patterns of remaining sagebrush habitat and loss due to cultivation, climatic trends, human population growth and peripherality of populations. However, future range loss may relate less to historical mechanisms and more to recent changes in land use and habitat condition, including energy developments and invasions by non-native species such as cheatgrass (Bromus tectorum) and West Nile virus. In conjunction with local measures of population performance, landscape-scale predictions of future range loss may be useful for prioritizing management and protection. Our results suggest that initial conservation efforts should focus on maintaining large expanses of sagebrush habitat, enhancing quality of existing habitats, and increasing habitat connectivity. [source]


    Influence of settlement time, human population, park shape and age, visitation and roads on the number of alien plant species in protected areas in the USA

    DIVERSITY AND DISTRIBUTIONS, Issue 6 2002
    Michael L. McKinney
    Abstract. I examined a data set of 77 protected areas in the USA (including national and state parks) to determine which of the following variables most strongly influence alien plant species richness: park area, climate (temperature and precipitation), native species richness, visitation rate, local human population size, total road length, park shape and duration of European settlement. Many of these predictor variables are intercorrelated, so I used multiple regression to help separate their effects. In support of previous studies, native species richness was the best single predictor of alien species richness, probably because it was a good estimator of both park area and habitat diversity available for establishment of alien species. Other significant predictors of alien species richness were years of occupation of the area by European settlers and the human population size of adjacent counties. Climate, visitation rate, road length and park shape did not influence alien species richness. The proportion of alien species (alien richness/native richness) is inversely related to park area, in agreement with a previous study. By identifying which variables are most important in determining alien species richness, such findings suggest ways to reduce alien species establishment. [source]


    Testing a model for predicting the timing and location of shallow landslide initiation in soil-mantled landscapes

    EARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2003
    M. Casadei
    Abstract The growing availability of digital topographic data and the increased reliability of precipitation forecasts invite modelling efforts to predict the timing and location of shallow landslides in hilly and mountainous areas in order to reduce risk to an ever-expanding human population. Here, we exploit a rare data set to develop and test such a model. In a 1·7 km2 catchment a near-annual aerial photographic coverage records just three single storm events over a 45 year period that produced multiple landslides. Such data enable us to test model performance by running the entire rainfall time series and determine whether just those three storms are correctly detected. To do this, we link a dynamic and spatially distributed shallow subsurface runoff model (similar to TOPMODEL) to an in,nite slope model to predict the spatial distribution of shallow landsliding. The spatial distribution of soil depth, a strong control on local landsliding, is predicted from a process-based model. Because of its common availability, daily rainfall data were used to drive the model. Topographic data were derived from digitized 1 : 24 000 US Geological Survey contour maps. Analysis of the landslides shows that 97 occurred in 1955, 37 in 1982 and ,ve in 1998, although the heaviest rainfall was in 1982. Furthermore, intensity,duration analysis of available daily and hourly rainfall from the closest raingauges does not discriminate those three storms from others that did not generate failures. We explore the question of whether a mechanistic modelling approach is better able to identify landslide-producing storms. Landslide and soil production parameters were ,xed from studies elsewhere. Four hydrologic parameters characterizing the saturated hydraulic conductivity of the soil and underlying bedrock and its decline with depth were ,rst calibrated on the 1955 landslide record. Success was characterized as the most number of actual landslides predicted with the least amount of total area predicted to be unstable. Because landslide area was consistently overpredicted, a threshold catchment area of predicted slope instability was used to de,ne whether a rainstorm was a signi,cant landslide producer. Many combinations of the four hydrological parameters performed equally well for the 1955 event, but only one combination successfully identi,ed the 1982 storm as the only landslide-producing storm during the period 1980,86. Application of this parameter combination to the entire 45 year record successfully identi,ed the three events, but also predicted that two other landslide-producing events should have occurred. This performance is signi,cantly better than the empirical intensity,duration threshold approach, but requires considerable calibration effort. Overprediction of instability, both for storms that produced landslides and for non-producing storms, appears to arise from at least four causes: (1) coarse rainfall data time scale and inability to document short rainfall bursts and predict pressure wave response; (2) absence of local rainfall data; (3) legacy effect of previous landslides; and (4) inaccurate topographic and soil property data. Greater resolution of spatial and rainfall data, as well as topographic data, coupled with systematic documentation of landslides to create time series to test models, should lead to signi,cant improvements in shallow landslides forecasting. Copyright © 2003 John Wiley & Sons, Ltd. [source]


    Edible insects: Traditional knowledge or western phobia?

    ENTOMOLOGICAL RESEARCH, Issue 5 2009
    Alan L. YEN
    Abstract With an increasing human population and environmental degradation, the world faces a major problem in providing adequate animal based proteins. Many traditional societies have used or still use insects as a protein source, while westernized societies are reluctant to use insects, despite being the major consumers of animal proteins. We now need to consider insects as a source of food for humans in a manner that acknowledges both the role of entomophagy in indigenous societies and the need for westernized societies to reduce the size of their environmental footprint with regard to food production. The situation on continents such as Africa, Asia, and Central and South America has some parallels to Australia in that there are two forces in operation: the sustainable traditional use of edible insects and the "westernization" of these societies leading to a movement away from entomophagy. However, the potential to reach a compromise is greater in these continents because entomophagy is already accepted. The major challenges will be establishing sustainable production systems that include food safety and security as well as environmental protection. Whether this will happen or not will depend upon: (i) a major change in attitude in westernized societies towards entomophagy; (ii) pressure to conserve remaining habitats in a sustainable manner; (iii) economic impetus to develop food production systems that include insects; and (iv) an acknowledgement that achieving adequate nutrition on a global basis will involve different diets in much of the developed world. [source]


    Human alcoholism studies of genes identified through mouse quantitative trait locus analysis

    ADDICTION BIOLOGY, Issue 4 2002
    Marissa A. Ehringer
    Coding region DNA sequence variants have been recently identified in several QTL candidate genes in a mouse model of differential sensitivity to alcohol [inbred long-sleep (ILS) and inbred short-sleep (ISS)]. This work has been extended into a human population characterized for their initial level of response to alcohol (LR). The coding region of one of the most promising of these candidate genes, zinc finger 133 (Znf133), has been sequenced completely in 50 individuals who participated in alcohol challenges at approximately age 20 and have been followed subsequently for the last 15 years. PCR products were obtained for the protein coding region of ZNF133 using human genomic DNA and directly sequenced using automated sequencers. Novel single nucleotide polymorphisms (SNPs) were detected by analyzing the sequence data using a suite of bioinformatics programs including Consed, Phred, Phrap and Polyphred. Five human SNPs were detected, two that correspond to amino acid changes in the protein, two that are silent DNA changes and one located in an intron. In this small sample, no significant association between any of the SNPs and alcohol diagnosis was detected. A follow-up of these SNPs in a larger sample should allow a more definitive conclusion to be reached. Significantly, the data presented here demonstrate the feasibility of directly testing genes in human alcoholic populations that had been identified first by comparative DNA sequencing of candidate genes located within mouse alcohol-related QTLs, even without detailed knowledge of the gene's function. [source]


    Lessons from the past: the collapse of Jamaican coral reefs

    FISH AND FISHERIES, Issue 2 2009
    Marah J. Hardt
    Abstract Since Pre-Columbian times, humans have exploited Jamaican marine ecosystems with significant consequences for flora and fauna. This study focuses on the history of reef fish exploitation in Jamaica, from first human occupation to the present day, to determine how past fishing activities contributed to subsequent declines in the coral reef ecosystem. The pattern of declining reef fish populations was nonlinear. Reef fish first declined in prehistoric times but then potentially recovered, following genocide of the native human population. Reduced fishing pressure lasted until the mid-19th century. At that time, depletion of reef fish populations again occurred with a precipitous decline from the 1850s to the 1940s. The final shift from relatively abundant to overfished marine fauna corresponded to subtle changes in fish trap design as well as development of recreational fishing. Government subsidies throughout the second half of the 20th century exacerbated the declines. This analysis shows that local artisanal fisheries with relatively low levels of effort and seemingly subtle shifts in technology can significantly impact the coral reef ecosystem and that declines occurred decades to centuries before modern ecological studies began. This research shows how historical analysis can be a powerful tool to minimize shifted baselines and establish realistic targets for recovery and sustainable management of marine ecosystems. [source]


    Stable nitrogen isotope ratios of macrophytes and associated periphyton along a nitrate gradient in two subtropical, spring-fed streams

    FRESHWATER BIOLOGY, Issue 8 2007
    LORETO DE BRABANDERE
    Summary 1. An increase in human population and associated changes in land use have caused an increase in groundwater nitrate concentrations throughout central Florida. Within the region, this nitrate-laden groundwater returns to the surface via numerous large springs that serve as the origin of flow for many coastal streams and rivers. These rivers can exhibit strong nitrate gradients because of the high nutrient uptake potential of the rivers. 2. We hypothesised that downstream declines in nitrate concentrations would be manifested spatially as increases in the ,15N of the residual pool of nitrate, macrophytes and periphyton as a consequence of isotopic fractionation associated with preferential use of 14NO3,. This hypothesis was tested in two spring-fed river systems, the Chassahowitzka and Homosassa rivers, along Florida's central Gulf of Mexico coast. 3. In general, ,15N values of nitrate, macrophytes and periphyton increased with decreasing fraction of nitrate remaining in each of the two study systems. The fractionation associated with nitrate uptake by macrophytes and associated periphyton was determined from the relationship between ,15N of both constituents of the macrophyte community and the fraction of nitrate removed from the system. Values for fractionation by macrophytes and periphyton ranged from 1.9, to 3.6, and from 0.7, to 2.5,, respectively. [source]


    Impact of inter-individual differences in drug metabolism and pharmacokinetics on safety evaluation

    FUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 6 2004
    J.L.C.M. Dorne
    Abstract Safety evaluation aims to assess the dose,response relationship to determine a dose/level of exposure for food contaminants below which no deleterious effect is measurable that is ,without appreciable health risk' when consumed daily over a lifetime. These safe levels, such as the acceptable daily intake (ADI) have been derived from animal studies using surrogates for the threshold such as the no-observed-adverse-effect-level (NOAEL). The extrapolation from the NOAEL to the human safe intake uses a 100-fold uncertainty factor, defined as the product of two 10-fold factors allowing for human variability and interspecies differences. The 10-fold factor for human variability has been further subdivided into two factors of 100.5 (3.16) to cover toxicokinetics and toxicodynamics and this subdivsion allows for the replacement of an uncertainty factor with a chemical-specific adjustment factor (CSAF) when compound-specific data are available. Recently, an analysis of human variability in pharmacokinetics for phase I metabolism (CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4, hydrolysis, alcohol dehydrogenase), phase II metabolism (N-acetyltransferase, glucuronidation, glycine conjugation, sulphation) and renal excretion was used to derive pathway-related uncertainty factors in subgroups of the human population (healthy adults, effects of ethnicity and age). Overall, the pathway-related uncertainty factors (99th centile) were above the toxicokinetic uncertainty factor for healthy adults exposed to xenobiotics handled by polymorphic metabolic pathways (and assuming the parent compound was the proximate toxicant) such as CYP2D6 poor metabolizers (26), CYP2C19 poor metabolizers (52) and NAT-2 slow acetylators (5.2). Neonates were the most susceptible subgroup of the population for pathways with available data [CYP1A2 and glucuronidation (12), CYP3A4 (14), glycine conjugation (28)]. Data for polymorphic pathways were not available in neonates but uncertainty factors of up to 45 and 9 would allow for the variability observed in children for CYP2D6 and CYP2C19 metabolism, respectively. This review presents an overview on the history of uncertainty factors, the main conclusions drawn from the analysis of inter-individual differences in metabolism and pharmacokinetics, the development of pathway-related uncertainty factors and their use in chemical risk assessment. [source]


    The common fragile site FRA16D and its associated gene WWOX are highly conserved in the mouse at Fra8E1

    GENES, CHROMOSOMES AND CANCER, Issue 2 2002
    Kurt A. Krummel
    Recently, several common fragile sites (CFSs) have been cloned and characterized, including the two most frequently observed in the human population, FRA3B and FRA16D. In addition to their high frequency of breakage, FRA3B and FRA16D colocalize with genes crossing large regions of breakage. At FRA3B, the fragile histidine triad (FHIT) gene spans more than 1 Mb, and at FRA16D, the WWOX gene spans more than 750 kb. It has also been shown that in Mus musculus, a CFS Fra14A2 and the mouse Fhit gene are conserved in the orthologous region of the genome. In this study, we positioned the ortholog to WWOX (Wox1) at chromosome band 8E1 in the mouse genome. To determine whether, like Fra14A2 and Fhit, Fra8E1 and Wox1 colocalized in the mouse, we prepared bacterial and yeast artificial chromosome probes, and we hybridized them to aphidicolin-treated mouse metaphase chromosomes. Our data demonstrate that Wox1 colocalizes with Fra8E1. Furthermore, the sequence from this region, including introns, is highly conserved over at least a 100-kb region. This evolutionary conservation suggests that the two most active CFSs share many features, and that CFSs and their associated genes may be necessary for cell survival. © 2002 Wiley-Liss, Inc. [source]


    SNOWSHED CONTRIBUTIONS TO THE NOOKSACK RIVER WATERSHED, NORTH CASCADES RANGE, WASHINGTON,

    GEOGRAPHICAL REVIEW, Issue 2 2002
    ANDREW BACH
    ABSTRACT. Meltwater contributes to watershed hydrology by increasing summer discharge, delaying the peak spring runoff, and decreasing variability in runoff. High-elevation snowshed meltwater, including glacier-derived input, provides an estimated 26.9 percent of summer streamflow (ranging annually from 16 to 40 percent) in the Nooksack River Basin above the town of Deming, Washington, in the North Cascades Range. The Nooksack is a major spawning river for salmon and once was important for commercial, recreational, and tribal fishing, and in the past its flow met the demands of both human and aquatic ecosystems. But the river is already legally overallocated, and demand is rising in response to the rapidly growing human population. Variability in snowshed contributions to the watershed is considerable but has increased from an average of 25.2 percent in the 1940s to an average of 30.8 percent in the 1990s. Overall stream discharge shows no significant increase, suggesting that the glaciers are melting, and/or precipitation levels (or other hydrologic factors) are decreasing at about the same rate. If glaciers continue to recede, they may disappear permanently from the Cascades. If that occurs, their summer contribution to surface-water supplies will cease, and water-management policies will need drastic revision. [source]


    Soil,atmosphere exchange of CH4, CO, N2O and NOx and the effects of land-use change in the semiarid Mallee system in Southeastern Australia

    GLOBAL CHANGE BIOLOGY, Issue 9 2010
    IAN GALBALLY
    Abstract The semiarid and arid zones cover a quarter of the global land area and support one-fifth of the world's human population. A significant fraction of the global soil,atmosphere exchange for climatically active gases occurs in semiarid and arid zones yet little is known about these exchanges. A study was made of the soil,atmosphere exchange of CH4, CO, N2O and NOx in the semiarid Mallee system, in north-western Victoria, Australia, at two sites: one pristine mallee and the other cleared for approximately 65 years for farming (currently wheat). The mean (± standard error) rates of CH4 exchange were uptakes of ,3.0 ± 0.5 ng(C) m,2 s,1 for the Mallee and ,6.0 ± 0.3 ng(C) m,2 s,1 for the Wheat. Converting mallee forest to wheat crop increases CH4 uptake significantly. CH4 emissions were observed in the Mallee in summer and were hypothesized to arise from termite activity. We find no evidence that in situ growing wheat plants emit CH4, contrary to a recent report. The average CO emissions of 10.1 ± 1.8 ng(C) m,2 s,1 in the Mallee and 12.6 ± 2.0 ng(C) m,2 s,1 in the Wheat. The average N2O emissions were 0.5 ± 0.1 ng(N) m,2 s,1 from the pristine Mallee and 1.4 ± 0.3 ng(N) m,2 s,1 from the Wheat. The experimental results show that the processes controlling these exchanges are different to those in temperate systems and are poorly understood. [source]


    Contrasting response of native and alien plant species richness to environmental energy and human impact along alpine elevation gradients

    GLOBAL ECOLOGY, Issue 6 2009
    Lorenzo Marini
    ABSTRACT Aim, We tested whether the species,energy and species,human relationships vary between native and both naturalized and casual alien species richness when other environmental variables had been taken into account. Location, Trento Province, a region (c. 6200 km2) on the southern border of the European Alps (Italy), subdivided into 156 contiguous (c. 37.5 km2) cells and ranging in elevation from 66 to 3769 m. Methods, Data were separated into three subsets, representing richness of natives, naturalized aliens and casual aliens and separately related to temperature, human population and various environmental correlates of plant species diversity. We applied ordinary least squares and simultaneous autoregressive regressions to identify potential contrasting responses of the three plant status subsets and hierarchical partitioning to evaluate the relative importance of the predictor variables. Results, Variation in alien plant species richness along the region was almost entirely explained by temperature and human population density. The relationships were positive but strongly curvilinear. Native species richness was less strongly related to either factor but was positively related to the presence of calcareous bedrock. Native species richness had a decelerating positive relationship with temperature (R2= 55%), whereas naturalized and casual aliens had a positive accelerating relationship explaining 86% and 62% of the variation in richness, respectively. Native species richness had a positive decelerating relationship with population density (R2= 42%), whilst both alien subsets had a positive accelerating relationship. Main conclusions, Alien species richness was higher in areas with the most rich and diverse assemblages of native species. Areas at high altitudes are not especially prone to alien invasion due to energy constraints, low propagule pressure and disturbance, even considering a potential increased in temperature. Thus, if we consider future environmental change, we should expect a stronger response of aliens than natives in the currently warm, urbanized, low-altitude areas than in cold, high-altitude areas where human population density is low. [source]


    Lack of response to exogenous interferon-, in the liver of chimpanzees chronically infected with hepatitis C virus,,

    HEPATOLOGY, Issue 4 2007
    Robert E. Lanford
    The mechanism of the interferon-alpha (IFN,),induced antiviral response is not completely understood. We recently examined the transcriptional response to IFN, in uninfected chimpanzees. The transcriptional response to IFN, in the liver and peripheral blood mononuclear cells (PBMCs) was rapidly induced but was also rapidly down-regulated, with most interferon-alpha,stimulated genes (ISGs) returning to the baseline within 24 hours. We have extended these observations to include chimpanzees chronically infected with hepatitis C virus (HCV). Remarkably, using total genome microarray analysis, we observed almost no induction of ISG transcripts in the livers of chronically infected animals following IFN, dosing, whereas the response in PBMCs was similar to that in uninfected animals. In agreement with this finding, no decrease in the viral load occurred with up to 12 weeks of pegylated IFN, therapy. The block in the response to exogenous IFN, appeared to be HCV-specific because the response in a hepatitis B virus,infected animal was similar to that of uninfected animals. The lack of a response to exogenous IFN, may be due to an already maximally induced ISG response because chronically HCV-infected chimpanzees already have a highly up-regulated hepatic ISG response. Alternatively, negative regulation may block the response to exogenous IFN,, yet it does not prevent the continued response to endogenous ISG stimuli. The IFN, response in chronically HCV-infected chimpanzees may be mechanistically similar to the null response in the human population. Conclusion: In chimpanzees infected with HCV, the highly elevated hepatic ISG expression may prevent the further induction of ISGs and antiviral efficacy following an IFN, treatment. (HEPATOLOGY 2007.) [source]


    Variation and infectivity neutralization in influenza

    IMMUNOLOGY, Issue 1 2006
    Marcel Knossow
    Summary Worldwide epidemics of influenza are caused by viruses that normally infect other species, particularly waterfowl, and that contain haemagglutinin membrane glycoproteins (HAs) to which the human population has no immunity. Anti-HA immunoglobulins neutralize influenza virus infectivity. In this review we outline structural differences that distinguish the HAs of the 16 antigenic subtypes (H1,16) found in viruses from avian species. We also describe structural changes in HA required for the effective transfer to humans of viruses containing three of them, H1, H2 and H3, in the 1918 (Spanish), the 1957 (Asian) and the 1968 (Hong Kong) pandemics, respectively. In addition, we consider changes that may be required before the current avian H5 viruses could pass from human to human. [source]


    Distribution of killer cell immunoglobulin-like receptor genes in Poles

    INTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 4-5 2008
    E. Majorczyk
    Summary Killer cell immunoglobulin-like receptors (KIRs) present on natural killer cells and minor subpopulations of T cells recognize class I human leucocyte antigen (HLA) molecules on the surface of target cells. Humans differ by the presence or absence of some KIR genes on their chromosomes. As KIRs are important for the outcome of tissue transplantation (particularly for haematopoietic stem cell transplantation) and possibly for pregnancy and autoimmune diseases, knowledge of the KIR gene distribution in a given human population is of practical value. Therefore, we tested 363 healthy individuals from Western Poland for the presence or absence of KIR genes. Results are compared with those published for other human populations. KIR gene frequencies in Poles are close to these in other Caucasoids but different from those in Asian and African populations, and particularly distant from those in Australian Aborigines. [source]


    Zoo and aquarium animal management and conservation: current trends and future challenges

    INTERNATIONAL ZOO YEARBOOK, Issue 1 2003
    M. HUTCHINS
    The turn of the century appears to be a good time to examine the role of zoos and aquariums, both in the past and present, and to predict what role these organizations will play in animal management and conservation in the future. In this review three main trends are considered: (1) the loss of wildlife habitats and, therefore, wildlife, (2) the increase in the number of animal-welfare and animal-rights organizations, and (3) the continued urbanization of the Earth's human population. Several predictions and positive action points are given for each trend and if these are taken on board and developed, zoos and aquariums of the future may become leaders in conservation, education and science. [source]


    Twenty years of rest returns grazing potential, but not palatable plant diversity, to Karoo rangeland, South Africa

    JOURNAL OF APPLIED ECOLOGY, Issue 4 2010
    Colleen L. Seymour
    Summary 1.,Up to 73% of the world's rangelands are degraded, and increasing demand for meat in developing countries and a growing human population are likely to exert even greater pressures on rangelands in the next 20,50 years. Restoration of rangeland grazing potential and resilience is therefore important, particularly in the face of climate change. 2.,We investigated the influence of past stocking rates (from 1910 to 1987), rainfall, and current grazing regimes (from 1988 to 2008) on plant assemblages, grazing potential, and diversity of palatable species in southern Karoo rangelands, South Africa. 3.,We used herbivore exclusion experiments to test whether resting rangeland for 20 years enables recovery of plant assemblages (where seed sources are present within 50 m), regardless of previous grazing history. Mean annual rainfall over this period was 15% higher than the mean annual rainfall for the preceding 80 years and included two exceptionally wet years. 4.,While rainfall was a primary driver of total vegetation cover, grazing history explained differences in plant species composition: plots with shared historical grazing intensity were more similar than plots with the same grazing regimes between 1988 and 2008. 5.,In historically heavily-grazed exclusion plots, cover of the palatable species Tripteris sinuata (formerly Osteospermum sinuatum) returned to levels comparable to that in both exclusion and lightly-grazed plots with a moderate grazing history. Five palatable species (Pteronia empetrifolia, Tetragonia spicata, Berkheya spinosa, Hereroa latipetala and Ruschia spinosa) failed to re-establish, however, despite the presence of seed-producing plants nearby. Furthermore, only cover of P. empetrifolia increased significantly in historically moderately-grazed plots. Cover of unpalatable plants (e.g. Pteronia pallens) increased in all plots over time. 6.Synthesis and applications. These findings suggest that present species composition of arid shrublands reflects historical management at time scales greater than 20 years. Despite high rainfall enabling the return of grazing potential through recovery of a single forage species, rest alone did not ensure the return of all palatable species, with implications for rangeland resilience. Restoring the full suite of palatable species over management timeframes will require more complex interventions such as reseeding or selective clearing. [source]


    Correlates of biological soil crust abundance across a continuum of spatial scales: support for a hierarchical conceptual model

    JOURNAL OF APPLIED ECOLOGY, Issue 1 2006
    MATTHEW A. BOWKER
    Summary 1Desertification negatively impacts a large proportion of the global human population and > 30% of the terrestrial land surface. Better methods are needed to detect areas that are at risk of desertification and to ameliorate desertified areas. Biological soil crusts are an important soil lichen-moss-microbial community that can be used toward these goals, as (i) bioindicators of desertification damage and (ii) promoters of soil stability and fertility. 2We identified environmental factors that correlate with soil crust occurrence on the landscape and might be manipulated to assist recovery of soil crusts in degraded areas. We conducted three studies on the Colorado Plateau, USA, to investigate the hypotheses that soil fertility [particularly phosphorus (P), manganese (Mn) and zinc (Zn)] and/or moisture limit soil crust lichens and mosses at four spatial scales. 3In support of the soil fertility hypothesis, we found that lichen,moss crusts were positively correlated with several nutrients [Mn, Zn, potassium (K) and magnesium (Mg) were most consistent] at three of four spatial scales ranging from 3·5 cm2 in area to c. 800 km2. In contrast, P was negatively correlated with lichen,moss crusts at three scales. 4Community composition varied with micro-aspect on ridges in the soil crust. Three micro-aspects [north-north-west (NNW), east-north-east (ENE) and TOP] supported greater lichen and moss cover than the warmer, windward and more xeric micro-aspects [west-south-west (WSW) and south-south-east (SSE)]. This pattern was poorly related to soil fertility; rather, it was consistent with the moisture limitation hypothesis. 5Synthesis and application. Use of crusts as desertification bioindicators requires knowledge of a site's potential for crust cover in the absence of desertification. We present a multi-scale model of crust potential as a function of site properties. Future quantitative studies can use this model to guide sampling efforts. Also, our results suggest new directions in restoration research: enhancement of moisture residence time and fertilization with key nutrients (Mn, Zn, K and Mg). Re-establishment of soil crusts in desertified lands will help regain lost soil stability and fertility, and facilitate plant re-establishment. [source]


    The function of the Egr1 transcription factor in cartilage formation and adaptation to microgravity in zebrafish, Danio rerio

    JOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2010
    M. Muller
    Summary Osteoporosis is one of the major concerns for an ageing human population and for passengers on long-term space flights. Teleosts represent a potentially interesting alternative for studying bone physiology. In zebrafish (Danio rerio), the cartilaginous elements that form the pharyngeal arches derive from cranial neural crest cells, whose proper patterning and morphogenesis require reciprocal interactions with other tissue types such as pharyngeal endoderm, ectoderm and mesoderm. We show how the zebrafish can be used to study the function of signal transduction pathways, such as the Fgf pathway, or that of particular genes, such as the zinc finger transcription factor Egr1, in pharyngeal skeleton formation and maintenance. We investigate the changes caused by microgravity and chemical treatments on zebrafish. We analyze early gene expression modification using whole genome microarray experiments and the long-term consequences by staining bone structures. [source]


    Oestrogenic activity of isobutylparaben in vitro and in vivo

    JOURNAL OF APPLIED TOXICOLOGY, Issue 4 2002
    P. D. Darbre
    Abstract The alkyl esters of p -hydroxybenzoic acid (parabens) are used widely as preservatives in foods, pharmaceuticals and cosmetics to which the human population is exposed. Recent studies have reported that methylparaben, ethylparaben, n -propylparaben and n -butylparaben all possess oestrogenic activity in several in vitro assays and in animal models in vivo. This study reports on the oestrogenic activity of isobutylparaben in a panel of assays in vitro and in vivo. Isobutylparaben was able to displace [3H]oestradiol from cytosolic oestrogen receptor , of MCF7 human breast cancer cells by 81% at 100 000-fold molar excess. Using a clonal line of MCF7 cells containing a stably transfected oestrogen-responsive ERE-CAT reporter gene, CAT gene expression could be increased by isobutylparaben such that the magnitude of the response was the same at 10,5 M isobutylparaben as with 10,8 M 17,-oestradiol. Isobutylparaben could also increase expression of the endogenous oestrogen-responsive pS2 gene in MCF7 cells and maximal expression at 10,5 M isobutylparaben could be inhibited with the anti-oestrogen ICI 182 780. The proliferation of two oestrogen-dependent human breast cancer cell lines MCF7 and ZR-75-1 could be increased with isobutylparaben such that at concentrations of 10,5 M the proliferation response was of the same magnitude as with 10,8 M 17,-oestradiol. Evidence for oestrogen receptor mediation of proliferation effects was provided by the inability of isobutylparaben to influence the growth of oestrogen-unresponsive MDA-MB-231 human breast cancer cells and by the ability of the anti-oestrogen ICI 182 780 to inhibit the isobutylparaben effects on MCF7 cell growth. The proliferation response to 10,10 M 17,-oestradiol was not antagonized with isobutylparaben at any concentration from 10,9 M to 10,4 M in either MCF7 or ZR-75-1 cells. Finally, subcutaneous administration of isobutylparaben was able to increase the uterine weight in the immature mouse after three daily doses of 1.2 or 12.0 mg per mouse. Previous work using linear-alkyl-chain parabens has shown that oestrogenic activity increases with alkyl chain length from methylparaben to n -butylparaben. The results here show that branching of the alkyl chain to isobutylparaben increases oestrogenic activity beyond that of the equivalent length linear alkyl chain in n -butylparaben. Copyright © 2002 John Wiley & Sons, Ltd. [source]