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PubMed2005

Is premating isolation in Drosophila overestimated due to uncontrolled factors?

Sexual isolation in Drosophila is typically measured by multiple-choice mating tests. While many environmental variables during such tests are controlled by the researcher, there are some factors that are usually uncontrolled. We demonstrate, using Drosophila melanogaster and D. pseudoobscura flies, that the temperature of rearing, pre-adult density, and level of consanguinity, can all produce differences in mating propensity between genetically equivalent flies. These differences in mating propensity, in turn, can give rise to statistically significant results in multiple-choice mating tests, leading to positive isolation values and the artifactual inference of sexual isolation between populations. This fact agrees with a nonrandom excess of significant positive tests found in a review of the literature of Drosophila intraspecific mating choice. An overestimate of true cases of sexual isolation in Drosophila in the literature can, therefore, not be ruled out.

Adaptation, Physiological↗

PubMedDate not supplied

Monitoring of diabetes in children.

There is increasing evidence to show that a high degree of metabolic control in diabetes mellitus delays and reduces the severity and incidence of the microvascular complications of diabetes. The goals of appropriate therapy for diabetes should hence include an all-out effort to achieve as near normal metabolism as possible but it should be individualized accordingly. In actual practice it is difficult to achieve "good" control especially in diabetic children without attendant hypoglycaemia and its sequelae. Diabetic control is difficult to define in clinical terms, and the maintenance of metabolic control in diabetes involves a complex interaction of pathological, physiological, psychological, familial, social and environmental variables. The aims in insulin-dependent diabetic children is to ensure optimal emotional and physical health of the child or adolescent. The various modalities available for monitoring or assessment of diabetic control shall be discussed.

Adolescent↗

PubMed1994

Yersinia ssp. in surface water in San Luis, Argentina.

Yersinia spp. was examined in three rivers and two lakes located in the Province of San Luis, Argentina, over a 1-year period. Water samples were concentrated either by Moore's gauze technique or by filtering through diatomaceous earth. Five enrichment media: yeast extract--Bengal rose broth (YER) with bile-oxalate-sorbose broth (BOS); 67 mmol/L phosphate-buffered saline (pH 7.6; PBS); PBS enriched with a 1% mannitol and 1% peptone (PBSMP); PBS with lyzed 0.5% sheep blood (PBSB); Wauters broth (W); and five plating media: Mac Conkey agar (MC); Salmonella--Shigella agar (SS); 5% sheep blood agar (BA); lactose-sucrose-urea agar (LSU) and irgasan-novobiocin agar (IN) were used. The following strains were isolated: Y. intermedia B1 O:4,32-4,33 Lis Xz (four strains), Y. intermedia B1 O:57 Lis Xo (one strain), Y. intermedia B2 O:57 Lis Xo (one strain), Y. enterocolitica B1 O:10-34 Lis Xz (one strain), and Y. frederiksenii undetermined biovar, O:16-16,29 Lis Xz (two strains). The incidence of isolation of Yersinia spp. was 7.14%. YER-BOS proved to be the best enrichment method since it allowed the highest recovering Yersinia spp. strains. Among plating media, the best results were obtained with MC. Apparently, the isolation of Yersinia spp. can be related to environmental variables such as temperature differences between cold and warm seasons. Negative results obtained during virulence assays suggest that isolated strains lack the pathogenic potential against man.

Argentina↗

PubMed2004

Physiological dendrogram of Claviceps spp. based on sucrose metabolism in submerged cultures and its comparison with phylogenetic tree.

Sixteen isolates of Claviceps spp. were analyzed for the production of polysaccharides, oligosaccharides, and sucrose metabolism under conditions of submerged fermentation. Physiological markers calculated by the Verhulst-Pearl law were used for hierarchical cluster analysis. Low correlation was found between physiologically based dendrogram and phylogenetic analysis constructed from an alignment of rDNA sequences. To confirm the intraspecific uniformity of physiological markers three isolates of C. africana from different hosts and locations were included. The influence of genotype, physiological variability, environmental location and habitat on metabolite production is discussed.

Claviceps↗

PubMedDate not supplied

The borderline hypertensive rat (BHR): a new model for the study of environmental factors in the development of hypertension.

While many studies have attempted to produce hypertension through the use of various environmental stressors, few have succeeded in producing chronic elevations in blood pressure beyond levels considered to be borderline hypertensive (140-160 mm Hg systolic). The problem with most studies stems from the use of genetically normotensive animals and the selection of stressors to which animals readily adapt. A new approach is suggested, which recognizes the role of genetics in human essential hypertension. Animals with one hypertensive parent do not develop spontaneous hypertension but show a more sensitive cardiovascular response to environmental stressors than animals with normotensive parents. Preliminary studies revealed that animals with a mixed genetic history of hypertension develop spontaneous borderline hypertension. When subjected to shock-shock conflict, these borderline hypertensive rats (BHR) developed permanent hypertension that failed to abate even after a ten-week, shock-free recovery period. The hypertension was accompanied by elevated heart weight to body weight ratios and by significant cardiac pathology. Subsequent work has demonstrated that these animals also become hypertensive when fed a high-sodium diet. Finally, in a series of exercise studies, we found that BHRs subjected to a shock stressor were protected against stress-induced hypertension if they exercised daily. The potential of this model for studies of the mechanisms by which environmental variables produce permanent hypertension is discussed.

Aging↗

PubMed2003

Structure of microbial communities in Sphagnum peatlands and effect of atmospheric carbon dioxide enrichment.

Little is known about the structure of microbial communities in Sphagnum peatlands, and the potential effects of the increasing atmospheric CO2 concentration on these communities are not known. We analyzed the structure of microbial communities in five Sphagnum-dominated peatlands across Europe and their response to CO2 enrichment using miniFACE systems. After three growing seasons, Sphagnum samples were analyzed for heterotrophic bacteria, cyanobacteria, microalgae, heterotrophic flagellates, ciliates, testate amoebae, fungi, nematodes, and rotifers. Heterotrophic organisms dominated the microbial communities and together represented 78% to 97% of the total microbial biomass. Testate amoebae dominated the protozoan biomass. A canonical correspondence analysis revealed a significant correlation between the microbial community data and four environmental variables (Na+, DOC, water table depth, and DIN), reflecting continentality, hydrology, and nitrogen deposition gradients. Carbon dioxide enrichment modified the structure of microbial communities, but total microbial biomass was unaffected. The biomass of heterotrophic bacteria increased by 48%, and the biomass of testate amoebae decreased by 13%. These results contrast with the absence of overall effect on methane production or on the vegetation, but are in line with an increased below-ground vascular plant biomass at the same sites. We interpret the increase in bacterial biomass as a response to a CO2-induced enhancement of Sphagnum exudation. The causes for the decrease of testate amoebae are unclear but could indicate a top-down rather than a bottom-up control on their density.

Amoeba↗

PubMed1998

Automated routing of DICOM CT, MR, and CR images: solving the pitfalls of vendor-specific DICOM implementations.

This paper details our experience in developing and implementing an automated DICOM Image Router. This workstation serves as a gateway between image acquisition devices and image display and storage devices. Images are checked for demographic input errors and data format inconsistencies between the source and destination devices. Based on the configured rules, and image may be held for manual correction and/or distributed to multiple locations. Distribution is based on easily configured environmental variables and rules files which may be changed as needed. For example, CT images are typically sent to the archive and to a radiologist's display workstation. If the patient came from the Emergency Department, a copy of the images are sent to a clinician display workstation located in the Emergency Department. If the patient has suffered trauma to the head, a copy of the images are sent to a display workstation in the Neurosurgery Department for possible consultation. The software was developed on a UNIX-based platform and utilizes a Fast Ethernet network. To date, images from a variety of devices have been acquired: General Electric HiSpeed CT/I scanner, General Electric Signa MRI scanner, Philips Thoravision Digital Chest unit, and Fuji AC-3CS Computed Radiography (CR) unit. Each device has presented new challenges in providing a uniform look to patient demographics in the PACS archive. The workstation also provides a buffer in the event of network outages, storing images for later transmission when the network and/or a workstation recover.

Diagnostic Imaging↗

PubMed1999

Fish Growth in Marine Culture Systems: A Challenge for Biotechnology.

: Aquaculture production is constrained largely by the growth efficiency of the species being produced. Nutritional approaches have played an important part in improving this situation, but, it is argued, the room for further improvement using such established techniques is limited. Alternative ways of improving fish production by utilizing recent biotechnological advances are explored and assessed as to their potential for commercialization in the near future. Transgenic technologies promise a revolution in aquaculture, but it is considered that consumer resistance may delay the use of transgenic fish for food production. An alternative approach could be the breeding of transgenic fodder plants without the amino acid deficiencies of existing alternatives to fish meal in aquaculture diets. The use of probiotics could reduce antibiotic use on fish farms while they might also provide the basis for "smart" diets, tailored to specific purposes by the inclusion of microorganisms. The selection and genetic engineering of nitrifying and denitrifying bacteria could also pave the way for fully enclosed, recirculating marine culture systems, which would allow control of the environmental variables that currently restrain marine fish culture.

Journal Article↗

PubMed2005

Physical activity of adults aged 50 years and older in Switzerland.

OBJECTIVE: This study explores the prevalence of guideline-compliant physical activity (PA) behavior based on socio-demographic, health-related and environmental variables. METHODS: Cross-sectional data of the Swiss Health Survey 2002 were used in a Swiss population segment aged 50+. Four categories of PA were created with respect to Swiss and US guidelines: "moderate sports/exercise", "vigorous sports/exercise", "habitual PA", and "optimal PA" (i.e. combined variable used when both "vigorous sports/exercise" and "habitual PA" apply). Sedentary lifestyle was a fifth category. RESULTS: In the total sample considered for analysis (N = 8405) the prevalence of guideline-compliant PA was: 9.1% moderate sports/exercise; 18.2% vigorous sports/exercise; 45% habitual PA; 8.7% optimal PA. Almost 50% of the age groups 65-79 and 80+ were involved in habitual PA. Higher socio-economic status was associated with involvement in moderate sports/exercise, vigorous sports/exercise, or optimal PA. In contrast, lower socioeconomic status was associated with habitual PA. While living in an urban or rural environment had no differentiating effect on sports/exercise, living in rural areas was associated with a sedentary lifestyle and little involvement in habitual PA and/or optimal PA. Self-reported good health and/or health orientation were associated with vigorous sports/exercise, habitual PA and optimal PA, regardless of whether the person had chronic health problems or not. CONCLUSION: Habitual PA seems to have the greatest potential for increasing overall guideline-compliant activity levels. A behavioral/cognitive and political/environmental approach to improving PA is suggested.

Adult↗

PubMed2005

Plant intelligence.

Intelligent behavior is a complex adaptive phenomenon that has evolved to enable organisms to deal with variable environmental circumstances. Maximizing fitness requires skill in foraging for necessary resources (food) in competitive circumstances and is probably the activity in which intelligent behavior is most easily seen. Biologists suggest that intelligence encompasses the characteristics of detailed sensory perception, information processing, learning, memory, choice, optimisation of resource sequestration with minimal outlay, self-recognition, and foresight by predictive modeling. All these properties are concerned with a capacity for problem solving in recurrent and novel situations. Here I review the evidence that individual plant species exhibit all of these intelligent behavioral capabilities but do so through phenotypic plasticity, not movement. Furthermore it is in the competitive foraging for resources that most of these intelligent attributes have been detected. Plants should therefore be regarded as prototypical intelligent organisms, a concept that has considerable consequences for investigations of whole plant communication, computation and signal transduction.

Animals↗

PubMed2007

Population dynamics and regulation in the cave salamander Speleomantes strinatii.

Time series analysis has been used to evaluate the mechanisms regulating population dynamics of mammals and insects, but has been rarely applied to amphibian populations. In this study, the influence of endogenous (density-dependent) and exogenous (density-independent) factors regulating population dynamics of the terrestrial plethodontid salamander Speleomantes strinatii was analysed by means of time series and multiple regression analyses. During the period 1993-2005, S. strinatii population abundance, estimated by a standardised temporary removal method, displayed relatively low fluctuations, and the autocorrelation function (ACF) analysis showed that the time series had a noncyclic structure. The partial rate correlation function (PRCF) indicated that a strong first-order negative feedback dominated the endogenous dynamics. Stepwise multiple regression analysis showed that the only climatic factor influencing population growth rate was the minimum winter temperature. Thus, at least during the study period, endogenous, density-dependent negative feedback was the main factor affecting the growth rate of the salamander population, whereas stochastic environmental variables, such as temperature and rainfall, seemed to play a minor role in regulation. These results stress the importance of considering both exogenous and endogenous factors when analysing amphibian long-term population dynamics.

Animals↗

PubMed2000

Genetic dissection of the molecular pathogenesis of severe infection.

A fundamental question for the intensivist is why some individuals but not others succumb to life-threatening infection. A growing body of evidence indicates that both the risk of acquiring infection and the risk of developing severe complications are determined by host genetic factors. These include a number of single gene defects with devastating consequences, e. g. interferon-gamma receptor mutations that lead to fatal infections with ubiquitous mycobacteria, but such examples are relatively rare. Of greater importance for routine clinical practice is the potentially vast number of genetic variants with subtle effects on the regulation or function of specific immunological, physiological and metabolic mediators. Such polygenic traits do not obey simple patterns of familial segregation seen for monogenic disorders, and their clinical investigation is further complicated by the environmental variability of infectious exposure. Recent advances in this field have therefore largely stemmed from hospital-based case-controlled studies that have uncovered disease associations with specific DNA polymorphisms in candidate gene regions. For example, tumour necrosis factor polymorphisms have been associated with susceptibility to malaria and other infections; chemokine receptor polymorphisms with susceptibility to HIV; natural resistance-associated macrophage protein 1 with tuberculosis; and mannose binding lectin polymorphisms with meningococcal disease. A much greater number of genetic associations will emerge as the full extent of human genomic diversity becomes known. The challenge for clinical investigators is to generate an epidemiological framework for population- and family-based association studies, which is sufficiently robust to exclude population artifacts and sufficiently powerful to be able to dissect true disease-causing polymorphisms from linked genetic markers. In the long term this approach promises to identify host mediators that are critical for pathogenesis and immunity and to yield molecular insights into the complex processes of human gene regulation. This information is likely to be of considerable value in designing more effective approaches to the treatment and prevention of life-threatening infectious disease.

Communicable Diseases↗

PubMed1998

The development of addiction to d-amphetamine in an animal model: same principles as for alcohol and opiate.

We have established a rat model that reflects the course of development of alcohol and opiate addiction. The present study with d-amphetamine aimed to define general principles in the development of an addiction. Male rats had a continuous free choice between d-amphetamine solutions (100, 200 and 400 mg/l) and water for 47 weeks. An initial intake of high doses of d-amphetamine during the first weeks of drug choice was followed by an individually stable pattern of drug consumption of moderate drug doses. During this period of controlled consumption (from week 10 to week 40), the voluntary intake of d-amphetamine depended on individual factors (dominant rats: 0.37+/-0.02 mg/kg per day, subordinate rats: 0.57+/-0.05 mg/kg per day) and environmental variables (group housing: 0.21+/-0.02 mg/kg per day, single housing: 0.41+/-0.03 mg/kg per day). Beginning with week 41, voluntary d-amphetamine consumption progressively increased (1.9+/-0.2 mg/kg per day in week 47), although the experimental conditions remained unchanged. Drug intake during a retest (free choice as before) after 6 months of drug deprivation revealed that the rats had persistently lost their control over drug intake and were no longer able to adjust drug taking to internal and external conditions. These addicted rats took very high drug doses, even when all d-amphetamine solutions but not water were adulterated with bitter tasting quinine (6.6+/-0.6 mg/kg per day; age-matched controls: 0.37+/-0.04 mg/kg per day). Forced intake of d-amphetamine for 47 weeks (7.1+/-0.3 mg/kg per day) via the drinking fluid caused physical dependence (hyperreactivity during withdrawal) but did not lead to drug addiction (voluntary intake in the retest with adulteration: 0.42+/-0.04 mg/kg per day). Both the temporal development and the prerequisites of psychostimulant addiction were in principle the same as for alcohol and opiates.

Animals↗

PubMed2003

Sediment microbial community composition and methylmercury pollution at four mercury mine-impacted sites.

Mercury pollution presents a globally significant threat to human and ecosystem health. An important transformation in the mercury cycle is the conversion of inorganic mercury to methylmercury, a toxic substance that negatively affects neurological function and bioaccumulates in food chains. This transformation is primarily bacterially mediated, and sulfate-reducing bacteria (SRB) have been specifically implicated as key mercury methylators in lake and estuarine sediments. This study used phospholipid fatty acid (PLFA) analysis to investigate sediment microbial community composition at four abandoned mercury mine-impacted sites in the California Coast Range: the Abbott, Reed, Sulphur Bank, and Mt. Diablo mines. Differences in watershed and hydrology among these sites were related to differences in microbial community composition. The Abbott and Sulphur Bank mines had the highest levels of methylmercury. Floc (a type of precipitate that forms when acid mine drainage contacts lake or river water) and sediment samples differed in terms of several important environmental variables and microbial community composition, but did not have statistically different methylmercury concentrations. Quantification of PLFA biomarkers for SRB (10Mel6:0 for Desulfobacter and i17:1 for Desulfovibrio) revealed that Desulfobacter and Desulfovibrio organisms made up higher percentages of overall microbial biomass at the Sulphur Bank and Mt. Diablo mines than at the Abbott and Reed mines. Correlations between these SRB biomarker fatty acids and methylmercury concentrations suggest that Desulfobacter and Desulfovibrio organisms may contribute to methylmercury production in the Abbott, Reed, and Sulphur Bank mines but may not be important contributors to methylmercury in the Mt. Diablo Mine.

California↗

PubMed2005

Dynamic of virioplankton abundance and its environmental control in the Charente estuary (France).

The Charente River provides nutrient- and virus-rich freshwater input to the Marennes Oléron Basin, the largest oyster-producing region in Europe. To evaluate virioplankton distribution in the Charente Estuary and identify which environmental variables control dynamic of virioplankton abundance, five stations defined by a salinity gradient (0-0.5, 0.6-5, 13-17, 20-24, and higher than 30 PSU) were surveyed over a year. Viral abundance was related to bacterioplankton abundance and activities, photosynthetic pigments, nutrient concentration, and physical parameters (temperature and salinity). On a spatial scale, virus displayed a decreasing pattern seaward with abundance ranging over the sampling period from 1.4x10(7) to 20.8x10(7) viruses mL-1 making virioplankton the most abundant component of planktonic microorganisms in the Charente Estuary. A good correlation was found between viral and bacterial abundance (rs=0.85). Furthermore, bacterial abundance was the most important predictor of viral abundance explaining alone between 66% (winter) and 76% (summer) of viral variability. However, no relation existed between viral abundance and chlorophyll a. Temporal variations in viral distributions were mainly controlled by temperature through the control of bacterial dynamics. Spatial variations of viral abundance were influenced by hydrodynamic conditions especially during the winter season where virioplankton distribution was entirely driven by mixing processes.

Bacteria↗

PubMed2005

Bacterial community succession in natural river biofilm assemblages.

Temporal bacterial community changes in river biofilms were studied using 16S rRNA gene-based polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) followed by sequence analysis. Naturally occurring biofilms were sampled in 2001 during an undisturbed 7-month low-water period in the River Garonne (SW France). During the sampling period epilithic biomass exhibited a particular pattern: two 3-month periods of accumulation that resulted in two peaks in summer and fall, each at about 25 g ash-free dry mass per square meter. Bacterial community DGGE profiles differed between the summer and fall biomass peaks and shared only 30% common operational taxonomic units (OTUs), suggesting the influence of seasonal factors on these communities. During the second biomass accrual phase, bacterial richness and the appearance of new OTUs fitted a conceptual model of bacterial biofilm succession. During succession, five OTUs (corresponding to Dechloromonas sp., Nitrospira sp., and three different Spirosoma spp.) exhibited particular patterns and were present only during clearly defined successional stages, suggesting differences in life-history strategies for epilithic bacteria. Co-inertia analysis of DGGE banding patterns and physical-chemical data showed a significant relationship between community structure and environmental conditions suggesting that bacterial communities were mainly influenced by seasonal changes (temperature, light) and hydrodynamic stability. Within the periods of stability, analysis of environmental variables and community patterns showed the dominant influence of time and maturation on bacterial community structure. Thus, succession in these naturally occurring epilithic biofilm assemblages appears to occur through a combination of allogenic (seasonal) and autogenic changes.

Bacteria↗

PubMed1999

Pelagic Bacteria-Particle Interactions and Community-Specific Growth Rates in Four Lakes along a Trophic Gradient.

Abstract The relationships between bacterial concentration, bacterial production, and cell-specific activity of both free and attached bacteria and environmental factors such as suspended solids, nutrients, and temperature were examined in four lakes, two in New Zealand and two in Switzerland. Estimates of cell-specific production were obtained by microautoradiographic counts of [3H]thymidine-labeled cells. Bacteria attached to particles accounted for only 1.3 to 11.6% of the total bacterial abundance, but showed overall 20-fold higher specific growth rates and were relatively more active than their free counterparts. On average, 80 to 100% of epibacteria were attached to organic particles. The abundance and production of free and attached bacteria were positively correlated; however, relationships between these fractions and some environmental variables differed. Cell-specific activities of active bacteria were not equivalent to mean cellular activities of the entire bacterial community and differed in their relationship to trophic state. [3H]Thymidine-positive bacteria were more tightly linked to chlorophyll a than were total bacteria. Our findings indicate that production by attached bacteria, fueled by phytoplankton carbon, supplies "new" free bacteria to the bacterial community. Our results support the idea that particulate organic matter acts as a source of dissolved nutrients to free bacteria. Bottom-up control of bacterial biomass, as shown by regressions of biomass vs production, appeared to be stronger in two ultraoligotrophic lakes than in two more eutrophic ones.

Journal Article↗

PubMed1999

Spatial and Temporal Assessment of Diazotroph Assemblage Composition in Vegetated Salt Marsh Sediments Using Denaturing Gradient Gel Electrophoresis Analysis.

> Abstract Diazotroph assemblage compositions were assessed in rhizosphere sediments from the tall and short form Spartina alterniflora growth zones over an annual cycle. Sediment cores were collected for DNA extraction and nitrogenase (acetylene reduction) activity assays, and porewater samples were analyzed for several chemical parameters in March, June, September, and December 1997. These data were collected to determine if within- or between-zone differences in the diazotroph assemblage composition correlated with differences in key environmental variables or acetylene reduction activity. Acetylene reduction rates differed between zones and within a zone over an annual period. Soluble sulfide concentrations were higher in the short form S. alterniflora zone on all dates except those in June and differed within both zones on different sample dates. nifH sequences were recovered from rhizosphere sediment DNA by PCR amplification using nifH specific primers. These amplimers were analyzed using denaturing gradient gel electrophoresis (DGGE), and the resulting patterns were compared by neural network and linear discriminant analyses. Ten prominent amplimers, four of which were apparent heteroduplexes, were observed. DGGE banding profiles showed minor differences among sampling dates and between sample zones, but the overall banding pattern was remarkably consistent. This reflects overall similarity between the amplifiable diazotroph assemblages in the tall and short S. alterniflora growth zones and substantial seasonal stability in assemblage composition.http://link.springer-ny.com/link/service/journals/00248/bibs/38n2p157.html

Journal Article↗