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PubMed2003

Latitudinal divergence of common frog (Rana temporaria) life history traits by natural selection: evidence from a comparison of molecular and quantitative genetic data.

The relative roles of natural selection and direct environmental induction, as well as of natural selection and genetic drift, in creating clinal latitudinal variation in quantitative traits have seldom been assessed in vertebrates. To address these issues, we compared molecular and quantitative genetic differentiation between six common frog (Rana temporaria) populations along an approximately 1600 km long latitudinal gradient across Scandinavia. The degree of population differentiation (QST approximately 0.81) in three heritable quantitative traits (age and size at metamorphosis, growth rate) exceeded that in eight (neutral) microsatellite loci (FST = 0.24). Isolation by distance was clear for both neutral markers and quantitative traits, but considerably stronger for one of the three quantitative traits than for neutral markers. QST estimates obtained using animals subjected to different rearing conditions (temperature and food treatments) revealed some environmental dependency in patterns of population divergence in quantitative traits, but in general, these effects were weak in comparison to overall patterns. Pairwise comparisons of FST and QST estimates across populations and treatments revealed that the degree of quantitative trait differentiation was not generally predictable from knowledge of that in molecular markers. In fact, both positive and negative correlations were observed depending on conditions where the quantitative genetic variability had been measured. All in all, the results suggest a very high degree of genetic subdivision both in neutral marker genes and genes coding quantitative traits across a relatively recently (< 9000 years) colonized environmental gradient. In particular, they give evidence for natural selection being the primary agent behind the observed latitudinal differentiation in quantitative traits.

Animals↗
PubMed2003

Local adaptation of an anuran amphibian to osmotically stressful environments.

Water salinity is an intense physiological stress for amphibians. However, some species, such as Bufo calamita, breed in both brackish and freshwater environments. Because selection under environmentally stressful conditions can promote local adaptation of populations, we examined the existence of geographic variation in water salinity tolerance among B. calamita populations from either fresh or brackish water ponds in Southern Spain. Comparisons were made throughout various ontogenetic stages. A combination of field transplant and common garden experiments showed that water salinity decreased survival probability of individuals in all populations, prolonged their larval period, and reduced their mass at metamorphosis. However, significant population x salinity interactions indicated that the population native to brackish water (Saline) had a higher salinity tolerance than the freshwater populations, suggesting local adaptation. Saline individuals transplanted to freshwater environments showed similar survival probabilities, length of larval period, and mass at metamorphosis than those native to freshwater. This indicates that increased tolerance to osmotic stress does not imply a loss of performance in freshwater, at least during the larval and juvenile phases. Despite the adaptive process apparently undergone by Saline, all populations still shared the same upper limit of embryonic stress tolerance (around 10 g/l), defining a window of salinity range within which selection can act. Significant differences in embryonic and larval survival in brackish water among sibships for all populations suggest the existence of a genetic basis for the osmotic tolerance.

Adaptation, Physiological↗
PubMed2002

Denaturing gradient gel electrophoresis (DGGE) approaches to study the diversity of ammonia-oxidizing bacteria.

Denaturing gradient gel electrophoresis (DGGE) of PCR amplicons of the ammonia monooxygenase gene (amoA) was developed and employed to investigate the diversity of ammonia-oxidizing bacteria (AOB) in four different habitats. The results were compared to DGGE of PCR-amplified partial 16S rDNA sequences made with primers specific for ammonia-oxidizing bacteria. Potential problems, such as primer degeneracy and multiple gene copies of the amoA gene, were investigated to evaluate and minimize their possible impact on the outcome of a DGGE analysis. amoA and 16S rDNA amplicons were cloned, and a number of clones screened by DGGE to determine the abundance of different motility types in the clone library. The abundance of clones was compared to the relative intensity of bands emerging in the band pattern produced by direct amplification of the genes from the environmental sample. Selected clones were sequenced to evaluate the specificity of the respective primers. The 16S rDNA primer pair, reported to be specific for ammonia-oxidizing bacteria (AOB), generated several sequences that were not related to the known Nitrosospira-Nitrosomonas group and, thus, not likely to be ammonia oxidizers. However, no false positives were found among the sequences retrieved with the modified amoA primers. Some phylogenetic information could be deduced from the position of amoA bands in DGGE gels. The Nitrosomonas-like sequences were found within a denaturant range from 30% to 46%, whereas the Nitrosospira-like sequences migrated to 50% to 60% denaturant. The majority of retrieved sequences from all four habitats with high ammonia loads were Nitrosomonas-like and only few Nitrosospira-like sequences were detected.

Ammonia↗
PubMed1987

Guam amyotrophic lateral sclerosis-parkinsonism-dementia linked to a plant excitant neurotoxin.

The decline in the high incidence of amyotrophic lateral sclerosis, parkinsonism, and Alzheimer-type dementia among the Chamorro population of the western Pacific islands of Guam and Rota, coupled with the absence of demonstrable viral and hereditable factors in this disease, suggests the gradual disappearance of an environmental factor selectively associated with this culture. One candidate is seed of the neurotoxic plant Cycas circinalis L., a traditional source of food and medicine which has been used less with the Americanization of the Chamorro people after World War II. Macaques were fed the Cycas amino acid beta-N-methylamino-L-alanine, a low-potency convulsant that has excitotoxic activity in mouse brain, which is attenuated by N-methyl-D-aspartate receptor antagonists. These animals developed corticomoto-neuronal dysfunction, parkinsonian features, and behavioral anomalies, with chromatolytic and degenerative changes of motor neurons in cerebral cortex and spinal cord. In concert with existing epidemiological and animal data, these findings support the hypothesis that cycad exposure plays an important role in the etiology of the Guam disease.

Amino Acids, Diamino↗
PubMed2003

Elevated asthma and indoor environmental exposures among Puerto Rican children of East Harlem.

OBJECTIVE: East Harlem in New York City, a community with a large Puerto Rican population, has among the highest rates of asthma hospitalizations and mortality in the United States, but it is not known if the high rates are related to the ethnic composition, environmental or community factors, or if the higher rates reflect differentials in access to appropriate asthma care. A survey was conducted to: (a) estimate the prevalence of current asthma by ethnicity among school-age children, (b) assess indoor environmental risk factors for childhood asthma, and (c) assess health care utilization and school absences associated with childhood asthma. DESIGN: A cross-sectional survey of parents of elementary school children, using a self-administered questionnaire with a 12-month recall on asthma symptoms based on the International Study of Asthma and Allergies in Childhood. SETTING: Two public elementary schools in East Harlem (n = 1615 students 5-12 years of age). RESULTS: Among the 1319 respondents (response rate 82%), the prevalence for current asthma (doctor or nurse diagnosis at any time plus wheezing in the past 12 months) was 23%. Puerto Rican children had a prevalence of 35%. Puerto Rican children reported both higher symptomatic frequencies and higher rates of physician diagnosis. Living in a home where cockroaches, rats, or mice had been seen in the past month and with a dust-enhancing heating system also was associated with having asthma, regardless of ethnicity. Compared with other children with asthma, Puerto Rican children with asthma were more likely to live in homes where rats or mice had been seen in the past month. Regardless of ethnicity, children with more frequent, more severe asthma symptoms and incomplete asthma action plans were more likely to have visited the emergency department in the past year. Puerto Rican children were more likely to have missed school because of their asthma in the past year. CONCLUSION: The prevalence of current asthma was significantly higher among Puerto Ricans, who had higher symptomatic frequency and greater diagnosis rates. Although all children with asthma in the East Harlem study appear to be sensitive to selected indoor environmental risk factors, only Puerto Rican children with asthma appear to be sensitive to the presence of rodents in their buildings. However, their higher school absence rate suggests problems with routine asthma management that could be addressed by improved medical management, programs to help parents manage their children's asthma, or school staff assistance with medications.

Absenteeism↗
PubMed2005

Selected ion monitoring in quantitative gas-liquid chromatographic-mass spectrometric detection of fatty acid methyl esters from environmental samples.

To calculate selected ion monitoring (SIM) gas-liquid chromatography (GLC)-mass spectrometry (MS) results of phospholipid fatty acids (PLFAs) from environmental samples, coefficients were calculated for each fatty acid by dividing the sum of ion intensities in SCAN with that of ions followed in SIM. The SIM chromatogram areas were multiplied with the coefficients, and then processed as in SCAN. The results were compared to those obtained using calibration curves and SCAN. The calibration curve and coefficient based results had the greatest errors of 7.8 and 6.7%, respectively, outside standard deviations of SCAN percentages. The PLFA contents calculated using calibration curves and coefficients were 104.9+/-7.3% and 101.5+/-8.6%, respectively, of SCAN values. SIM increased sensitivity approximately 10-fold from SCAN, and the smallest detectable injected amount was approximately 50 ng (0.18 nmol) for 20 fatty acids, corresponding to 4 x 10(6) cells.

Environmental Monitoring↗
PubMed2000

Highly selective and efficient determination of US Environmental Protection Agency priority phenols employing solid-phase extraction and non-aqueous capillary electrophoresis.

Non-aqueous capillary electrophoresis has been used in the separation of a complete list of 26 priority phenols included in the 8041 US Environmental Protection Agency method and the 76/464/EEC European Union directive. A highly selective and efficient separation was obtained when the background electrolyte used was 150 mM ammonium acetate dissolved in N-methylformamide-acetonitrile (75:25). Solid-phase extraction was successfully assayed as an enrichment strategy for the analysis of low-concentration samples. A styrene-divinylbenzene functionalized cartridge provided excellent recoveries of phenols from water samples at neutral pH. The limits of quantification obtained permit the application of the proposed method to the determination of priority phenols in wastewater samples.

Electrophoresis, Capillary↗
PubMed2026

Finlay-Wilkinson random regression for yield and yield stability prediction in cereals.

Year-to-year climate variability poses a challenge for agriculture by increasing crop yield variability; therefore, there is a need to identify genotypes that can withstand these fluctuations. With the right selection criteria, genotypes with yield stability across variable environmental conditions can be selected. Methods such as Finlay-Wilkinson random regression (FWRR) may allow us to use sparse datasets-common in plant breeding pipelines-and incorporate genomic data to leverage phenotypic information from related genotypes to predict yield stability. Our objective was to examine how the number of environments and the variance among those environments affect stability predictions. We also integrate FWRR as a genomic prediction tool for characterizing yield stability, comparing it to the traditional genomic prediction models as a reference. We used three datasets: one highly unbalanced dataset for oats (Avena sativa L.) and two completely balanced datasets with different numbers of environments for barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.). We fit standard Finlay-Wilkinson (FW) and FWRR models to estimate grain yield and stability under various scenarios. We found that the estimated stability values obtained were similar using balanced datasets for FW or FWRR. FWRR also achieved moderate predictive ability for stability using unbalanced datasets under 10-fold cross-validation (CV1) with new genotypes. In terms of environmental representation, selecting the right set of environments for inclusion in the model was more important than adding more environments. Our results suggest the possibility of using FWRR to select stable genotypes earlier in line development, as well as to design resource-efficient stability-testing schemes.

Hordeum↗
PubMed2006

Adaptive response of a gene network to environmental changes by fitness-induced attractor selection.

Cells switch between various stable genetic programs (attractors) to accommodate environmental conditions. Signal transduction machineries efficiently convey environmental changes to the gene regulation apparatus in order to express the appropriate genetic program. However, since the number of environmental conditions is much larger than that of available genetic programs so that the cell may utilize the same genetic program for a large set of conditions, it may not have evolved a signaling pathway for every environmental condition, notably those that are rarely encountered. Here we show that in the absence of signal transduction, switching to the appropriate attractor state expressing the genes that afford adaptation to the external condition can occur. In a synthetic bistable gene switch in Escherichia coli in which mutually inhibitory operons govern the expression of two genes required in two alternative nutritional environments, cells reliably selected the "adaptive attractor" driven by gene expression noise. A mathematical model suggests that the "non-adaptive attractor" is avoided because in unfavorable conditions, cellular activity is lower, which suppresses mRNA metabolism, leading to larger fluctuations in gene expression. This, in turn, renders the non-adaptive state less stable. Although attractor selection is not as efficient as signal transduction via a dedicated cascade, it is simple and robust, and may represent a primordial mechanism for adaptive responses that preceded the evolution of signaling cascades for the frequently encountered environmental changes.

Adaptation, Biological↗
PubMedDate not supplied

Competition and survival of health service organizations: a population ecology approach.

The survival of health care organizations is viewed, in this article, from a population ecology perspective. This perspective provides insight into how organizational forms are differentiated on the basis of resource availability under different environmental conditions. Selected hypotheses and a rationale are presented to illustrate the applicability of the perspective to health services.

Delivery of Health Care↗
PubMed2002

Electronic labelling in recycling of manufactured articles.

The concept of a recycling system aiming at the recovery of resources from manufactured articles is proposed. The system integrates electronic labels for product identification and internet for global data exchange. A prototype for the recycling of electric motors has been developed, which implements a condition-based recycling decision system to automatically select the environmentally and economically appropriate recycling strategy, thereby opening a potential market for second-hand motors and creating a profitable recycling process itself. The project has been designed to evaluate the feasibility of electronic identification applied on a large number of motors and to validate the system in real field conditions.

Commerce↗
PubMed1984

[Limitations of the post mortem determination of intravital soft-tissue hemorrhages long after death].

Under experimental conditions we investigated the influence of various environmental conditions and different temperatures on extravasated blood in the galea for varying time periods. At 30 degrees C it took 5-6 days before we could no longer histologically identify either red blood corpuscles or hemoglobin. At 4 degrees C and 18 degrees C we succeeded in making the identification for a considerably longer time. The various environmental conditions selected had no essential influence at any temperature. The forensic application of these results is discussed using an actual case as an example.

Adult↗
PubMed2006

Genetic pleiotropy in Saccharomyces cerevisiae quantified by high-resolution phenotypic profiling.

Genetic pleiotropy, the ability of a mutation in a single gene to give rise to multiple phenotypic outcomes, constitutes an important but incompletely understood biological phenomenon. We used a high-resolution and high-precision phenotypic profiling approach to quantify the fitness contribution of genes on the five smallest yeast chromosomes during different forms of environmental stress, selected to probe a wide diversity of physiological features. We found that the extent of pleiotropy is much higher than previously claimed; 17% of the yeast genes were pleiotropic whereof one-fifth were hyper-pleiotropic. Pleiotropic genes preferentially participate in functions related to determination of protein fate, cell growth and morphogenesis, signal transduction and transcription. Contrary to what has earlier been proposed we did not find experimental evidence for slower evolutionary rate of pleiotropic genes/proteins. We also refute the existence of phenotypic islands along chromosomes but report on a remarkable loss both of pleiotropy and of phenotypic penetrance towards chromosomal ends. Thus, the here reported features of pleiotropy both have implications on our understanding of evolutionary processes as well as the mechanisms underlying disease.

Genes, Fungal↗
PubMed2005

Genetic variation along time in a Brazilian population of Aedes aegypti (Diptera: Culicidae), detected by changes in the esterase patterns.

Aedes aegypti from the Brazilian cities of São José do Rio Preto (SJ) and Goiânia (GO) were analyzed as to their esterase patterns and the results were compared with data obtained about 5 years before for SJ population. Esterase bands not detected in the previous study were now observed in mosquitoes from both SJ and GO populations, being the last considered a population resistant to insecticides. Other similarities between SJ and GO populations in this study, and some differences in comparison with the previous data on SJ were observed, involving, in addition to changes in band type, changes in frequency of mosquitoes expressing them and differential gene activation during development. As it is generally true for genetic features, changes in the esterase patterns are expected to be the result of factors such as selection by environmental conditions and genetic drift. In the present case, continuous use of insecticides aiming mosquito population size control in SJ by sanitary authorities could be involved in the observed changes. Changed esterases were classified as carboxylesterases and cholinesterases, which are enzymes already shown to take part in the development of resistance in several organisms. In addition, data obtained in the elapsed time by authorities responsible for the mosquito control has shown increasing insecticide resistance of SJ population mosquitoes parallel to increase in the total amount of esterases, reinforcing the mentioned possibility.

Aedes↗
PubMed1985

Relationship between autonomic and behavioral thermoregulation in the mouse.

Preferred ambient temperature (Ta) was measured in nine mice of the BALB/c strain using a temperature gradient. When tested over four consecutive days the mean preferred Ta was 30.9 degrees C. In another study using the same animals, metabolic rate, evaporative water loss, whole-body thermal conductance, and colonic temperature were measured at specific Ta's over a range of 18 to 34 degrees C. The preferred Ta of 30.9 degrees C was associated with the lower critical Ta (i.e., Ta below which metabolic rate increased) a 57% elevation in evaporative water loss when expressed in units of mg water evaporated per ml consumed oxygen, a thermal conductance that was 92% above baseline levels, and a normothermic colonic temperature of between 37.0 to 37.5 degrees C. The data indicate that mice will select an environmental temperature associated with a minimal energy expenditure but a higher than minimal rate of evaporation and higher thermal conductance.

Animals↗
PubMed1991

High frequency of the HLA-DRB1*0405-(Dw15)-DQw8 haplotype in Spaniards and its relationship to diabetes susceptibility.

A study of DR4 subtypes has been done in Spanish unrelated controls and insulin-dependent diabetics by using dot blot hybridization with specific DR4B1 exon-2 oligonucleotides and automated dideoxy DNA sequencing. Dw15-DQw8 is the predominant DR4 subtype present in our normal population (37%); this DR4 frequency characteristic singles out our population from all other Caucasoids tested so far and may also be a marker of the original Iberian paleo-North African population. Dw15-DQw8 is not significantly increased in our insulin-dependent diabetics sample and despite its relative high frequency in the control population it does not have a bearing in lowering insulin-dependent diabetes mellitus frequency of DR4-positive Spaniards. In addition, no particular DR4 split is by itself significantly increased in Spanish diabetics; this may indicate that selective diabetogenic environmental factors may be working upon DR4-positive individuals, but on genes (or gene products) other than DR or at least not upon the polymorphic sites of DRB1 exon-2 products.

Amino Acid Sequence↗