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PubMed2005

Common garden and natural selection experiments support ecotypic differentiation in the Dominican anole (Anolis oculatus).

The theory behind ecotypic differentiation and ecological speciation assumes a predominant role for natural selection working on characteristics with genetic variance, but experimental support for these assumptions is limited. Lesser Antillean anoles show marked ecotypic variation within islands and the potential for ecological speciation. Common garden rearing experiments on the Dominican anole (Anolis oculatus) suggest that the characters showing geographic variation have genetic variance and are not primarily determined by environmental plasticity. Replicated natural selection experiments using large-scale enclosures show that translocated montane samples experience significant (multivariate) directional selection in both wet and dry seasons in both males and females. The targets of selection appear to be spread among the various character systems. An experiment on 12 geographically segregated populations along a coastal xeric-montane rainforest gradient (four replicate enclosures) clearly showed that the magnitude of the directional selection intensity is positively related to the position along this gradient. The results of the common garden and natural selection experiments support the interpretation that the geographic differentiation is primarily driven by natural selection and are compatible with the potential for ecological speciation in this system.

Animals↗
PubMed2006

Co-selection of antibiotic and metal resistance.

There is growing concern that metal contamination functions as a selective agent in the proliferation of antibiotic resistance. Documented associations between the types and levels of metal contamination and specific patterns of antibiotic resistance suggest that several mechanisms underlie this co-selection process. These co-selection mechanisms include co-resistance (different resistance determinants present on the same genetic element) and cross-resistance (the same genetic determinant responsible for resistance to antibiotics and metals). Indirect but shared regulatory responses to metal and antibiotic exposure such as biofilm induction also represent potential co-selection mechanisms used by prokaryotes. Metal contamination, therefore, represents a long-standing, widespread and recalcitrant selection pressure with both environmental and clinical importance that potentially contributes to the maintenance and spread of antibiotic resistance factors.

Anti-Bacterial Agents↗
PubMed2003

A novel transcription factor involved in plant defense endowed with protein phosphatase activity.

In plants, expression of a disease-resistance character following perception of a pathogen involves massive deployment of transcription-dependent defenses. Thus, if rapid and effective defense responses have to be achieved, it is crucial that the pathogenic signal is transduced and amplified through pre-existing signaling pathways. Reversible phosphorylation of specific transcription factors, by a concerted action of protein kinases and phosphatases, may represent a mechanism for rapid and flexible regulation of selective gene expression by environmental stimuli. Here we identified a novel DNA-binding protein from tobacco plants, designated DBP1, with protein phosphatase activity, which binds in a sequence-specific manner to a cis- acting element of a defense-related gene and participates in its transcriptional regulation. This finding helps delineate a terminal event in a signaling pathway for the selective activation of early transcription-dependent defense responses in plants, and suggests that stimulus-dependent reversible phosphorylation of regulatory proteins may occur directly in a transcription protein-DNA complex.

Amino Acid Sequence↗
PubMed2005

Association of minimum inhibitory concentration cluster patterns with dairy management practices for environmental bacteria isolated from bulk tank milk.

Environmental bacteria have emerged over the past few years to become significant causes of mastitis. Bacteria in this group are often reported by practicing veterinarians to be increasingly resistant to intramammary therapy and responsible for elevated bulk tank somatic cell counts. The purpose of this study was to determine the extent of association of the minimum inhibitory concentrations for selected antimicrobial agents with environmental bacteria isolated from bulk tank milk on California dairies and their housing facilities, husbandry practices, and antimicrobic-use strategies. Bulk tank milk samples were collected from 2 dairy cooperatives that had their milk cultured at the Milk Quality Laboratory, University of California Davis, Veterinary Medicine Teaching and Research Center in Tulare, CA. Samples were collected from July 2001 through March 2002 on 88 d; and 404 environmental bacteria isolated from 93 dairies were found. Minimum inhibitory concentrations were determined on 337 of the isolates for 10 antimicrobial agents. Cluster analysis was performed on the minimum inhibitory concentration values for each organism, and 4 antimicrobial clusters with varying degrees of resistance were found.A 69-question survey questionnaire was completed on-farm for 49 of the 73 dairies that had at least 3 environmental bacterial isolates. The questionnaire sought information on housing facilities, milking management, mastitis prevention, antimicrobial usage strategies, and owner/veterinary involvement in disease control and prevention. Multinomial logistic regression analysis found significant associations between the antimicrobial agent-resistance cluster groups and some of the housing and bedding practices, failure to dry udders before milking, and antimicrobial treatment of nonmastitis conditions. No association was noted for antimicrobial agent treatment of mastitis and the resistance cluster patterns.

Animals↗
PubMed1983

Osteoarthritis in some developing countries.

Only a few studies on osteoarthritis (OA) have been performed in developing countries. They all concern African populations. OA occurs less frequently in developing populations. Whether this is due to genetic or environmental factors or to selective forces like an excessive mortality at younger ages, is difficult to decide. Development of criteria for clinical degenerative joint disease is recommended. Furthermore studies are proposed on the geographical distribution of specific joint OA, the concept of generalized OA, the pattern of joint involvement, the natural history of degenerative joint disease, and the role of occupation, sports, and environmental factors.

Adult↗
PubMed1993

The role of growth hormone in lines of mice divergently selected on body weight.

An understanding of the physiological and genetic changes which determine the response to selection is critical for both evolutionary theory and to assess the application of new molecular techniques to commercial animal breeding. We investigated an aspect of physiology, growth hormone (GH) metabolism, which might a priori have been expected to play a large part in the response of mouse lines selected for high or low body weight. Disruption of endogenous GH or addition of exogenous GH had similar proportionate effects on body weight in both lines of mice (although differences in body composition arose) suggesting that neither the production of GH nor receptor sensitivity to GH had been altered as a result of selection. This supports a 'pleiotropic model' of the response to selection: that many genes with diverse metabolic roles all contribute to the divergent phenotype. This result has significant commercial implications as it suggests that artificial selection, transgenic technology and environmental manipulation may be synergistic rather than antagonistic strategies.

Animals↗
PubMed1995

Emerging diseases and ecosystem instability: new threats to public health.

Ecologists have begun to describe an environmental distress syndrome, whereby widespread loss of top predators and harsh environmental conditions are encouraging the selection of opportunistic pests and pathogens across a wide taxonomic range of plants and animals. Environmental change and pollutants stress individuals and populations, and this may be reflected in the global resurgence of infectious disease as these stresses cascade through the community assemblages of species. In 1993, the sudden appearance of a virulent, rodent-borne hantavirus in the arid US Southwest accompanied anomalous weather patterns, and a novel Vibrio cholerae variant (O139 Bengal) emerged in Asia where marine ecosystems are experiencing a pandemic of coastal algal blooms, apparently harboring and amplifying the agent. This paper suggests a framework for integrating the surveillance of health outcomes and key reservoir and vector species, with ecological and climatic monitoring.

Animals↗
PubMed1996

Hair analysis in environmental medicine.

Hair analysis comprises the determination of minerals, trace elements and drugs. It is applied in Germany with increasing frequency in the recently established field of environmental medicine for biological monitoring of the internal metal/metalloid exposure. Besides a number of advantages hair analysis is impaired by the difficulty-to distinguish between endogenous and exogenous sources of metals in hair. Except for methylmercury, there are no critical limit values for trace elements in hair available. However, valid reference values for some metals and for nicotine in hair have been recently presented in the German Environmental Survey. The significance of selected substances in hair are as follows: Aluminium in hair is of no value in environmental medicine. For assessment of cadmium and inorganic arsenic exposure hair analysis is only suitable as a screening method based on large populations. Monitoring of lead in hair is a valuable screening method also for small groups, especially for children. Based on toxicokinetics and under consideration of practicability the optimal biomarker of methylmercury exposure is the hair concentration. For other mercury compounds hair analysis is of lower significance. Nicotine and cotinine measurements in hair provide a practical and proper method for estimating environmental tobacco smoke exposure and to validate smoker status in epidemiological studies.

Adolescent↗
PubMed2001

Environmental stress and mutational load in diploid strains of the yeast Saccharomyces cerevisiae.

The negative effect of permanent contamination of populations because of spontaneous mutations does not appear to be very high if judged from the relatively good health of humans or many wild and domesticated species. This is partly explained by the fact that, in diploids, the new mutations are usually located in heterozygous loci and therefore are masked by wild-type alleles. The expression of mutations at the phenotypic level may also strongly depend on environmental factors if, for example, deleterious alleles are more easily compensated under favorable conditions. The present experiment uses diploid strains of yeast in which mutations arise at high rates because a mismatch-repair protein is missing. This mutagenesis resulted in a number of new alleles that were in heterozygous loci. They had no detectable effect on fitness when the environment was benign. A very different outcome was seen when thermal shock was applied, where fitness of the mutation-contaminated clones was lower and more diverse than that of the nonmutagenized clones. This shows that the genetic load conferred by spontaneous mutations can be underestimated or even overlooked in favorable conditions. Therefore, genetic variation can be higher and natural selection more intense when environmental conditions are getting poorer. These conclusions apply, at least, to that component of variation that directly originates from spontaneous mutations (as opposed to the variation resulting from the history of selection).

Biological Evolution↗
PubMed1988

Efficacy of chemical dosing methods for isolating nontuberculous mycobacteria from water supplies of dialysis centers.

Investigations of nontuberculous mycobacterium (NTM) infections associated with various environmental sources have been hampered by the lack of adequate techniques for selective isolation of these organisms from environmental fluids. This study compared chemical dosing techniques for recovery of NTM from water samples collected from 115 randomly selected dialysis centers. Cell suspensions of NTM group II and IV isolates and gram-negative bacteria were exposed to solutions containing sodium hypochlorite (0.2 micrograms/ml of free available chlorine), formaldehyde (1, 0.75, or 0.5%), oxalic acid (1.25%), cetylpyridinium chloride (25 micrograms/ml), or cetyltrimethylammonium bromide (100 micrograms/ml). Results of standard membrane filtration assays with laboratory test strains and water samples from dialysis centers showed that 5 min of exposure to 1% formaldehyde effectively reduced gram-negative bacterial populations and allowed increased recovery of NTM in environmental fluids containing mixed microbial populations.

Cetrimonium↗
PubMed2006

Conserved phenotypic variation patterns, evolution along lines of least resistance, and departure due to selection in fossil rodents.

Within a group of organisms, some morphologies are more readily generated than others due to internal developmental constraints. Such constraints can channel evolutionary changes into directions corresponding to the greatest intraspecific variation. Long-term evolutionary outputs, however, depend on the stability of these intraspecific patterns of variation over time and from the interplay between internal constraints and selective regimes. To address these questions, the relationship between the structure of phenotypic variance covariance matrices and direction of morphological evolution was investigated using teeth of fossil rodents. One lineage considered here leads to Stephanomys, a highly specialized genus characterized by a dental pattern supposedly favoring grass eating. Stephanomys evolved in the context of directional selection related to the climatic trend of global cooling causing an increasing proportion of grasslands in southwestern Europe. The initial divergence (up to approximately 6.5 mya) was channeled along the direction of greatest intraspecific variation, whereas after 6.5 mya, morphological evolution departed from the direction favored by internal constraints. This departure from the "lines of least resistance" was likely the consequence of an environmental degradation causing a selective gradient strong enough to overwhelm the constraints to phenotypic evolution. However, in a context of stabilizing selection, these constraints actually channel evolution, as exemplified by the lineage of Apodemus. This lineage retained a primitive diet and dental pattern over the last 10 myr. Limited morphological changes occurred nevertheless in accordance with the main patterns of intraspecific variation. The importance of these lines of least resistance directing long-term morphological evolution may explain parallel evolution of some dental patterns in murine evolution.

Animals↗
PubMed2002

Extracellular enzymatic activity profiles in yeast and yeast-like strains isolated from tropical environments.

AIMS: The objective of this study was to investigate the extracellular enzymatic activity (EEA) profile of yeasts isolated from tropical environments of the Brazilian rain forest. This screening survey could constitute the first approach in selecting yeast strains of environmental origin potentially exploitable as enzyme producers. METHODS AND RESULTS: In this study, 348 yeast (193 ascomycetes and 155 basidiomycetes) and 46 yeast-like strains (Aureobasidium pullulans) were screened for their EEA profile. The spread occurrence of extracellular amylases, esterases, lipases, proteases, pectinases and chitinases appeared to be a strain-related character. CONCLUSIONS: Yeasts isolated from tropical environments could represent a promising source of EEA. Selected strains showed maximum levels of EEA under acidic or neutral conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated the potential for yeasts isolated from extreme environments as sources of industrially relevant enzymes for biotechnological purposes.

Ascomycota↗
PubMed1996

Machining operations and associated machining fluid exposures: issues for health and safety intervention in manufacturing.

The outline for a workshop discussion of intervention research in manufacturing industry is presented. The example used is the control of machining fluid exposures, a widespread exposure that is associated with risk of cancer, pulmonary disease, dermatitis, and several types of accident-related injuries. Relevant technical considerations for conducting intervention research include the selection of machining fluid for different machining purposes, the management of fluids in use, and the selection and maintenance of environmental controls. Equally important are nontechnical considerations including the need for creating labor-management health and safety committees, the use of administrative rules on job performance for both workers and management, and training on the role of individuals from either group in exposure control. Clarity concerning the objectives for an intervention study and plans for clear means to evaluate study outcomes is critical. Important study variables will include site selection, plant size, plant demographics, the involvement of workers in the study, a willing management, and concern for susceptible workers.

Accidents, Occupational↗
PubMed1992

A bioeconomic simulation model for a hierarchical swine breeding structure.

A stochastic computer model was developed to simulate individual pigs in a hierarchical breeding system. The bioeconomic model was designed as a tool to facilitate the evaluation of selection, culling, and management strategies for a three-tiered breeding structure. Events such as mating, farrowing, and selection occurred weekly. Variables included number of pigs born alive, survival rate from birth to weaning, average daily gain and backfat at 110 kg, number of pigs weaned, feed per gain, days from weaning to 110 kg, age at puberty, and growth rate and weight of sows and service boars. Also included were probabilities of conception, return to estrus by week, survival, involuntary culling, male infertility, and unacceptable conformation. Variables important for selection were determined by breeding value, individual and maternal heterosis, parity, size of birth litter, sex, age of dam, genetic and environmental relationships between variables, and common litter, permanent, and random environmental effects. Variables derived from selection variables were computed by regression using phenotypic relationships between all variables. Also, a random environmental effect was added to predicted performance. Means and variances of variables differed between genetic lines. Production costs included feed, non-feed operating, fixed, and replacement stock costs. Income included market animals, culls, and replacements sold to lower tiers. Effects of changes in backfat on market value and sow maintenance feed costs were not modeled. An example is given to illustrate model output.

Animal Feed↗
PubMed1980

Multivariate relationships among visual-perceptual attributes and gross-motor tasks with different environmental demands.

This study investigated the multivariate inter-relationships of five visual perceptual variables (coincidence anticipation, field dependence/independence, perceptual speed, peripheral range, and spatial relations) and two performance stages of two gross motor tasks. The motor tasks, a ball task and a nonball task, had different temporal environmental demands. Eighty randomly selected women enrolled In general college physical education classes performed six trials of both motor tasks on two days. Promax factor analysis produced five factors accounting for 81% of the total variability and three low but significant (p less than.05) interfactor correlations. Factor I (ability to perform the ball task) was related both to Factor IV (ability to anticipate coincidence) and to Factor II (ability to extract and inter-relate pertinent environmental information). Factor III (ability to relate to the total environment and perform the nonball task) was related to Factor V (ability to detect motion peripherally).

Journal Article↗
PubMed2006

Community noise annoyance assessment in an urban agglomeration.

In urban areas community noise is one of the important factors in producing deterioration of both well-being and the quality of life. The aim of the study was to compare two noise annoyance surveys and two noise annoyance scales in the period of 15 years in selected areas of Slovak capital Bratislava, to calculate risks of community noise annoyance and disturbance in the observed samples. Noise annoyance risks were calculated by bivariate and stratified analysis in the form of odds ratio and Mantel-Haenszel weighted odds ratio from 2x2 and 2xn tables. The use of validated five-grade scale of noise annoyance assessment gives higher possibilities for more detailed analysis, allows to calculate the indicator--percentage of highly annoyed subjects (% HA), the rate of highly annoyed individuals. The percentage of highly annoyed subjects was 18% in the year 2004, which is comparable with recently published studies. The percentage of respondents that were not at all annoyed by road traffic noise has been decreased during the 15 year period by 10% (42% vs 32%). The increase of subjective community noise annoyance risks has been observed after 15 years as well. The sample from the year 2004 has been more annoyed by road traffic noise, neighbourhood noise, noise from entertainment facilities, noise from industry and railway noise. The highest risk increase has been observed in the entertainment facilities noise annoyance (OR(MH) =1.51; 95% CI = 0.90-2.52 vs OR(MH) = 4.47; 95% CI = 2.75-7.33). Using of standard five-grade noise annoyance questionnaire gives higher possibilities for data analysis in the studies investigating the influence of environmental noise annoyance on selected population groups (Tab. 3, Ref. 7).

Adult↗
PubMed1999

Laboratory evolution of peroxide-mediated cytochrome P450 hydroxylation.

Enzyme-based chemical transformations typically proceed with high selectivity under mild conditions, and are becoming increasingly important in the pharmaceutical and chemical industries. Cytochrome P450 monooxygenases (P450s) constitute a large family of enzymes of particular interest in this regard. Their biological functions, such as detoxification of xenobiotics and steroidogenesis, are based on the ability to catalyse the insertion of oxygen into a wide variety of compounds. Such a catalytic transformation might find technological applications in areas ranging from gene therapy and environmental remediation to the selective synthesis of pharmaceuticals and chemicals. But relatively low turnover rates (particularly towards non-natural substrates), low stability and the need for electron-donating cofactors prohibit the practical use of P450s as isolated enzymes. Here we report the directed evolution of the P450 from Pseudomonas putida to create mutants that hydroxylate naphthalene in the absence of cofactors through the 'peroxide shunt' pathway with more than 20-fold higher activity than the native enzyme. We are able to screen efficiently for improved mutants by coexpressing them with horseradish peroxidase, which converts the products of the P450 reaction into fluorescent compounds amenable to digital imaging screening. This system should allow us to select and develop mono- and di-oxygenases into practically useful biocatalysts for the hydroxylation of a wide range of aromatic compounds.

Catalysis↗