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PubMed1991

Environmental contaminants and biochemical responses in flatfish from the Hvaler Archipelago in Norway.

The levels of several environmental contaminants, including selected polyaromatic hydrocarbons (PAH), organochlorines (DDT/DDE, hexachlorobenzene), 15 polychlorinated biphenyl (PCB) congeners, and polychlorinated dibenzofurans and dibenzo-p-dioxins, PCDF/PCDD), and heavy metals (Cd, Hg, Pb, and As) were analyzed in muscle and liver of three different flatfish species (dab, Limanda limanda; flounder, Platichthys flesus; plaice, Pleuronectes platessa) caught by gill netting at different sites in the Hvaler Archipelago. Indices of biochemical effects in liver S9-fractions were studied by measuring cytochrome P450-dependent monooxygenase and UDP-glucuronyl transferase activities, and by immunoquantitating cytochrome P450 1A1 using an indirect enzyme-linked immunosorbent assay (ELISA). Only low levels of PCDD/PCDF, Cd, and Pb were observed, whereas PCB levels were significantly elevated in fish from the inner sites of the Archipelago compared to a reference site. The contaminant gradient toward the Glomma estuary was correlated with increased cytochrome P450 1A1 activity, measured as 7-ethoxyresorufin O-deethylase (EROD), and with immunoquantitated P450 1A1. In contrast, fish from the site at Idefjorden, although containing elevated contaminant levels, did not show elevated EROD activity, but apparently elevated P450 1A1 protein. These findings may reflect different pollution histories of the sites, and indicate the applicability of biochemical effect indices (i.e., EROD and P450 1A1 immunoquantitation) to monitoring studies. The integrated chemical-biochemical approach employed in this study can obviously be expanded to give fruitful information about cause-effect relationships in other contaminant situations.

Animals↗

PubMed1976

Genetic variation in constant environments.

Allozymic variation in proteins encoded by 32 gene loci was analyzed electrophoretically in 64 specimens from 6 localities representing 2 species of the spadefoot toads Pelobates syriacus and P. cultripes from Israel and Portugal, respectively. Out of the 32 loci examined, Esterase-1 was the only locus that proved strongly polymorphic in all 6 localities and in the 2 species. The pattern of genetic variation in Pelobates is best explained by the environmental variability model. Selection for homozygosity as an adaptive strategy seems to operate in the relatively constant and narrow subterranean niche.

Alleles↗

PubMedDate not supplied

Enhanced neuroendocrine response to insulin tolerance test performed under increased ambient temperature.

The hypothesis that an increase in ambient temperature modulates neuroendocrine response in clinically used provocative pituitary function tests was verified. Healthy male volunteers were subjected to insulin tolerance tests in two randomized trials. In the first trial hypoglycemia was induced by a bolus injection of insulin (0.1 U per kg of BW, i.v.) at room temperature. In the second trial, the subjects were exposed to increased ambient temperature for 45 min before insulin injection and for 45 min thereafter. The environmental temperature was selected to increase body temperature less than 1C. Under conditions of increased temperature basal hormone levels as measured in antecubital venous blood samples failed to be modified and the hypoglycemia was less severe. Nevertheless, the responses of most (beta-endorphin, ACTH, prolactin, catecholamines), but not all (growth hormone, cortisol), hormones to hypoglycemia were exaggerated. The remarkable increase in ACTH and beta-endorphin release was not accompanied by concomitant increase of plasma cortisol response. The sympathetic-adrenomedullary system was significantly activated, which was manifested particularly by enhanced norepinephrine release. Growth hormone response to hypoglycemia was not modified, while that of prolactin was enhanced. Thus during evaluation of neuroendocrine function under clinical conditions, changes in ambient and body temperature should not be underestimated.

Adrenocorticotropic Hormone↗

PubMed2005

A QTL located on chromosome 4A associated with dormancy in white- and red-grained wheats of diverse origin.

Improved resistance to preharvest sprouting in modern bread wheat (Triticum aestivum. L.) can be achieved via the introgression of grain dormancy and would reduce both the incidence and severity of damage due to unfavourable weather at harvest. The dormancy phenotype is strongly influenced by environmental factors making selection difficult and time consuming and this trait an obvious candidate for marker assisted selection. A highly significant Quantitative Trait Locus (QTL) associated with grain dormancy and located on chromosome 4A was identified in three bread wheat genotypes, two white- and one red-grained, of diverse origin. Flanking SSR markers on either side of the putative dormancy gene were identified and validated in an additional population involving one of the dormant genotypes. Genotypes containing the 4A QTL varied in dormancy phenotype from dormant to intermediate dormant. Based on a comparison between dormant red- and white-grained genotypes, together with a white-grained mutant derived from the red-grained genotype, it is concluded that the 4A QTL is a critical component of dormancy; associated with at least an intermediate dormancy on its own and a dormant phenotype when combined with the R gene in the red-grained genotype and as yet unidentified gene(s) in the white-grained genotypes. These additional genes appeared to be different in AUS1408 and SW95-50213.

Australia↗

PubMed2000

Influence of conflicting visual, inertial and substratal cues on head direction cell activity.

In order to navigate efficiently, animals can benefit from internal representations of their moment-to-moment orientation. Head-direction (HD) cells are neurons that discharge maximally when the head of a rat is oriented in a specific ("preferred") direction in the horizontal plane, independently from position or ongoing behavior. This directional selectivity depends on environmental and inertial cues. However, the mechanisms by which these cues are integrated remain unknown. This study examines the relative influence of visual, inertial and substratal cues on the preferred directions of HD cells when cue conflicts are produced in the presence of the rats. Twenty-nine anterior dorsal thalamic (ATN) and 19 postsubicular (PoS) HD cells were recorded from 7 rats performing a foraging task in a cylinder (76 cm in diameter, 60 cm high) with a white card attached to its inner wall. Changes in preferred directions were measured after the wall or the floor of the cylinder was rotated separately or together in the same direction by 45 degrees, 90 degrees or 180 degrees, either clockwise or counterclockwise. Linear regression analyses showed that the preferred directions of the HD cells in both structures shifted by approximately =90% of the angle of rotation of the wall, whether rotated alone or together with the floor (r2>0.87, P<0.001). Rotations of the floor alone did not trigger significant shifts in preferred directions. These results indicate that visual cues exerted a strong but incomplete control over the preferred directions of the neurons, while inertial cues had a small but significant influence, and substratal cues were of no consequence.

Animals↗

PubMed2002

Microbial transformation of elements: the case of arsenic and selenium.

Microbial activity is responsible for the transformation of at least one third of the elements in the periodic table. These transformations are the result of assimilatory, dissimilatory, or detoxification processes and form the cornerstones of many biogeochemical cycles. Arsenic and selenium are two elements whose roles in microbial ecology have only recently been recognized. Known as "essential toxins", they are required in trace amounts for growth and metabolism but are toxic at elevated concentrations. Arsenic is used as an osmolite in some marine organisms while selenium is required as selenocysteine (i.e. the twenty-first amino acid) or as a ligand to metal in some enzymes (e.g. FeNiSe hydrogenase). Arsenic resistance involves a small-molecular-weight arsenate reductase (ArsC). The use of arsenic and selenium oxyanions for energy is widespread in prokaryotes with representative organisms from the Crenarchaeota, thermophilic bacteria, low and high G+C gram-positive bacteria, and Proteobacteria. Recent studies have shown that both elements are actively cycled and play a significant role in carbon mineralization in certain environments. The occurrence of multiple mechanisms involving different enzymes for arsenic and selenium transformation indicates several different evolutionary pathways (e.g. convergence and lateral gene transfer) and underscores the environmental significance and selective impact in microbial evolution of these two elements.

Adenosine Triphosphatases↗

PubMed2006

Modelling wetland bird response to water level changes in the Lake Ontario - St. Lawrence River hydrosystem.

Lake Ontario and St. Lawrence River (LOSL) wetland bird abundance and diversity are greatly influenced by lake and river hydrology. Our study used an interdisciplinary ecosystem approach, blending avian and plant ecology, ecohydraulic, statistical ecology and modelling to evaluate potential impacts of water level fluctuations on indicator species representative of the wetland breeding bird assemblages in the entire LOSL freshwater system. Multi-year (2000-2003) bird surveys captured bird distribution and density in wetland habitats under varying degrees of water inandation, depth and fluctuation. Analyses revealed strong associations between estimated breeding pair densities and plant communities, water depth, and degree of water level fluctuation during the breeding season for a suite of wetland bird species using marsh, wet meadow, shrub swamp and treed swamp habitats. These quantitative associations were used to develop wetland bird performance indicators for use in a LOSL water regulation review study. Several bird species also nest at or near the water surface and are thus vulnerable to nest flooding or stranding. Changes to the seasonal hydrology of Lake Ontario and St. Lawrence River that result in an increased frequency or magnitude of these nest failure events may have a significant impact on regional population sustainability. Long term nest record databases were analyzed to create nesting flooding and stranding probability equations based on water level increases and decreases during the breeding season. These species-specific nesting relationships were incorporated into a reproduction index. Many breeding bird species were strongly associated with specific wetland plant communities. Predicted habitat suitability, as measured by estimated breeding pair density, can also change significantly within a specific wetland plant community based solely on changes in water depth during the breeding season. Three indicator species, Black Tern, Least Bittern and Virginia Rail were selected as key environmental performance indicators for alternate regulation plan comparisons. Water regulation criteria should be such that the long term diversity and abundance of wetland plant communities and frequency of spring flooding in marsh habitats during breeding are not reduced. Magnitude and frequency of water level change during the nesting season (May-July) can also adversely impact reproductive success of many wetland bird species. As such, regulation criteria that increase the seasonal magnitude and frequency of water level change may be detrimental to the long term viability of certain regional breeding bird populations.

Animals↗

PubMed1983

Phencyclidine and behavior: II. Active avoidance learning and radial arm maze performance.

Rats with injections of 4 or 8 mg/kg of phencyclidine (PCP) are impaired in the acquisition of active avoidance learning and radial arm maze performance. This impairment was not due to a change in detectability of aversive stimuli or the inability to perform the correct response. The primary deficit appears to be the inability of PCP injected animals to encode the appropriate attributes (e.g., environmental context, response selection, and emotion) associated with each task.

Animals↗

PubMedDate not supplied

The use of traditional toxicologic data in assessing neurobehavioral dysfunction.

In the United States, the regulation and testing of chemicals that may impact on human health is mandated by a number of different laws and regulated by several government agencies. Toxicologic screening in laboratory animals has created a major database for predicting adverse health effects of drugs, food and cosmetic ingredients, and manufactured chemicals. Test protocols and reporting requirements frequently differ between government agencies within the United States and between nations. Until recently, the emphasis for this required testing has been to identify those chemicals that may result in cancer or birth defects with little or no emphasis placed on neurobehavioral testing. The so-called "traditional toxicologic screen" presently includes acute, subchronic, chronic, teratology, and reproductive multispecies testing. The report for each segment of the test screen contains a myriad of data elements that have been observed by numerous technicians in the testing laboratory. These laboratory tests vary from general animal observations of animal body weight and food consumption to tests for hematology, blood chemistry, urinalysis, and histopathology. In addition, specialized tests may include other physiological measurements, neurologic tests, eye exams as well as functional testing to evaluate performance (e.g., open field, swimming maze, and T-maze). Reliability, quality control, and the difficulty in converting technician observation into quantifiable data elements that are free from bias is a primary concern for all testing laboratories. This paper focuses on the neurotoxicologic and behavioral information that can be gleaned from traditional toxicologic screens, the collection of study data, the effect of model selection, and the environmental considerations that may affect study outcome. The paper includes examples of compounds previously reported in the literature.

Animals↗

PubMed2004

Temperature-dependent expression patterns of grass carp fast skeletal myosin heavy chain genes.

Three types of myosin heavy chain cDNA clone named 10 degrees C, intermediate and 30 degrees C types were isolated from fast skeletal muscles of thermally acclimated grass carp Ctenopharyngodon idellus. Three clones encompassing parts of 3'-translated and entire 3'-untranslated regions showed high heterogeneities in their nucleotide sequences in the 3'-untranslated region. The comparison in the deduced amino acid sequence of the 10 degrees C-type clone with those of the intermediate- and 30 degrees C-type clones showed 88% and 89% identities, respectively. By contrast, the deduced amino acid sequence of the intermediate-type clone shared much higher identity of 97% with its 30 degrees C-type counterpart. Northern blot analysis demonstrated that the 10 degrees C- and 30 degrees C-type clones were predominantly expressed in grass carp acclimated to 10 and 30 degrees C, respectively. The intermediate type was expressed both in grass carp acclimated to 20 and 30 degrees C. Furthermore, expression patterns of the three myosin heavy chain genes were altered in accompaniment with seasonal temperature fluctuation. In autumn and winter grass carp expressed the 10 degrees C-type gene almost exclusively, whereas it was completely replaced by the intermediate- and 30 degrees C-type genes in spring and summer. These results suggest that tetraploid grass carp also undergo an adaptation to fluctuating environmental temperatures by selectively expressing fast skeletal myosin heavy chain isoforms as do diploid common carp previously reported.

Amino Acid Sequence↗

PubMed2005

Application of hollow fiber liquid phase microextraction for the determination of insecticides in water.

In the present work, a novel sample pre-treatment technique for the determination of trace concentrations of some insecticide compounds in aqueous samples has been developed and applied to the determination of the selected analytes in environmental water samples. The extraction procedure is based on coupling polypropylene hollow fiber liquid phase microextraction (HF-LPME) with gas chromatography by flame thermionic detection (GC-FTD). For the development of the method, seven organophosphorous insecticides (dichlorvos, mevinphos-cis, ethoprophos, chlorpyrifos methyl, phenthoate, methidathion and carbofenothion) and one carbamate (carbofuran) were considered as target analytes. Several factors that influence the efficiency of HF-LPME were investigated and optimized including agitation, organic solvent, sample volume, exposure time, salt additives and pH. The optimized methodology exhibited good linearity with correlation coefficient = 0.990. The analytical precision for the target analytes ranged from 4.3 to 11.1 for within-day variation and 4.6 to 12.0% for between-day variation. The detection limits for all analytes were found in the range from 0.001 to 0.072 microg/L, well below the limits established by the EC Drinking Water Directive (EEC 80/778). Relative recoveries obtained by the proposed method from drinking and river water samples ranged from 80 to 104% with coefficient of variations ranging from 4.5 to 10.7%. The present methodology is easy, rapid, sensitive and requires small sample volumes to screen environmental water samples for insecticide residues.

Chemical Fractionation↗

PubMed2006

Estimating the gasoline components and formulations toxicity to microalgae (Tetraselmis chuii) and oyster (Crassostrea rhizophorae) embryos: an approach to minimize environmental pollution risk.

Even though petrochemical contamination frequently occurs in the form of oil spills, it is thought that a greater danger to coastal habitats is posed by chronic petrochemical toxicity associated with urban run-off, in which gasoline water-soluble-fraction (WSF) plays an important role. The hypothesis of the entrepreneurs, who were associated to the scientists uncharged of this research, was that recycled petrochemical waste may provide different gasoline formulations, having different toxic properties; the correlation between the gasoline formulations and their components' toxicological effects might contribute to the reformulation of the products, in such a way that the gasoline generated could be less toxic and less harmful to the environment. The aim of this research was to determine the toxic effects of 14 different types of gasoline (formulated, in accordance with National Petroleum Agency standards, from petrochemical waste), on Tetraselmis chuii (microalgae culture) and Crassostrea rhizophorae (embryos). Microalgae and oyster embryos were exposed to different gasoline formulations water-soluble fractions (WSF) at a range of concentrations (0%, 4.6%, 10.0%, 22.0%, 46.0%, and 100%), for 96 and 24h, respectively. The tests were carried out under controlled conditions. End-points have been CI50-96h (concentration causing 50% growth inhibition in microalgae cultures) and EC50-24h (concentration causing abnormalities on 50% of the exposed embryos). Through these procedures, gasoline formulations, which represent the lowest environmental risk, were selected. Bioassays carried out on the 8 different gasoline components aimed to correlate gasoline toxicity with the toxic potential of its components. The analysis of principal components showed that the C9DI, a mixture of aromatic hydrocarbons of 9 carbon atoms, had the highest level of toxic potential, followed by C9S (a mixture of aromatics with 9-11 carbon atoms) and heavy naphtha. The results showed gasoline formulations 1-4 (monoaromatic hydrocarbons being the most conspicuous components) to be the least toxic, whilst formulations 12-14 (having higher content of C9DI, C9S and naphtha) were found to be the most harmful to organisms. This study led to the identification of the most toxic WSF gasoline components (C9DI and C9S), and to the possibility of developing more eco-compatible gasoline formulations.

Animals↗

PubMed2005

A redox switch hypothesis for the origin of two light reactions in photosynthesis.

Photosynthesis provides energy in the Earth's biosphere and oxygen in its atmosphere. For oxygen to be produced, two different light reactions must operate simultaneously and in series. Known anaerobic, photosynthetic bacteria contain one or other of these photosystems, but never both. Here, I propose that the two photosystems diverged, in structure and function, from a common ancestor, within a single, continuous, anaerobic lineage. In such cells, living examples of which are predicted, the two photosystems are isoenzymes encoded by orthologous genes under co-ordinated, redox regulatory control. A redox switch responds to defined environmental conditions and selects which set of genes is expressed. In these cells, the two photosystems are thus synthesised at different times. It is further proposed that the origin of oxygen-evolving photosynthesis was a simple mutation that disabled the redox switch, permitting simultaneous expression of the two sets of genes. The two, newly co-existing photosystems became connected by shared electron carriers, allowing generation of electrochemical potential high enough to oxidise water; an inexhaustible supply of reductant; and the selective advantages and pressures of an aerobic world.

Evolution, Molecular↗

PubMed2005

Phylogenetics by likelihood: evolutionary modeling as a tool for understanding the genome.

Molecular evolutionary studies provide a means of investigating how cells function and how organisms adapt to their environment. The products of evolutionary studies provide medically important insights to the source of major diseases, such as HIV, and hold the key to understand the developing immunity of pathogenic bacteria to antibiotics. They have also helped mankind understand its place in nature, casting light on the selective forces and environmental conditions that resulted in modern humans. The use of likelihood as a framework for statistical modeling in phylogenetics has played a fundamental role in studying molecular evolution, enabling rigorous and robust conclusions to be drawn from sequence data. The first half of this article is a general introduction to the likelihood method for inferring phylogenies, the properties of the models used, and how it can be used for statistical testing. The latter half of the article focuses on the emerging new generation of phylogenetic models that describe heterogeneity in the evolutionary process along sequences, including the recoding of protein coding sequence data to amino acids and codons, and various approaches for describing dependencies between sites in a sequence. We conclude with a detailed case study examining how modern modeling approaches have been successfully employed to identify adaptive evolution in proteins.

Animals↗

PubMed2006

Evaluation of biodegradability and oxidation degree of hospital wastewater using photo-Fenton process as the pretreatment method.

In this work, the photo-Fenton process was used for the pretreatment of hospital wastewater with the objective of improving its overall biodegradability and determining the degree of increased oxidation. The chemical oxygen demand (COD), 5-day biochemical oxygen demand (BOD5), total organic carbon (TOC) and toxicity towards the gram negative marine bioluminescent bacteria of the species V. fischeri were selected as the environmental sum parameters to follow the performance of this process. The enhancement of biodegradability, evaluated in terms of the BOD5/COD ratio, increased from 0.3 to 0.52 and the oxidation degree, calculated in terms of AOS, leveled up from -1.14 to +1.58 at the optimum conditions; a dosage ratio of COD:H2O2:Fe(II) at 1:4:0.1, and a reaction pH of 3. The reduction in the inhibition percentage from the toxicity test indicated the safe levels for micro-organisms in degrading the residual organic substance in this method. Almost total removal percentages of COD, BOD5, and TOC were found by a sequential activated sludge process for the pre-treated wastewater. Results obtained from this work indicated that the photo-Fenton process could be a suitable pretreatment method in reducing toxicity of pollutants and enhancing biodegradability of hospital wastewaters treated in a coupled photochemical-biological system.

Aerobiosis↗

PubMed2005

Neutrophil gene expression in rheumatoid arthritis.

There is now a growing awareness that infiltrating neutrophils play an important role in the molecular pathology of rheumatoid arthritis. In part, this arises from the fact that neutrophils have potent cytotoxic activity, but additionally from the fact that inflammatory neutrophils can generate a number of cytokines and chemokines that can have a direct influence on the progress of an inflammatory episode. Furthermore, the molecular properties of inflammatory neutrophils are quite different from those normally found in the circulation. For example, inflammatory neutrophils, but not blood neutrophils, can express cell surface receptors (such as MHC Class II molecules and FcgammaRI) that dramatically alter the way in which these cells can interact with ligands to modulate immune function. Cytokine/chemokine expression and surface expression of these novel cell surface receptors is dependent upon the neutrophil responding to local environmental factors to selectively up-regulate the expression of key cellular components via signalling pathways coupled to transcriptional activation. However, major changes in the expression levels of some proteins are also regulated by post-translational modifications that alter rates of proteolysis, and hence changes in the steady-state levels of these molecules.

Journal Article↗

PubMed2004

Linkage of a novel mercury resistance operon with streptomycin resistance on a conjugative plasmid in Enterococcus faecium.

It has been shown that the mercury in dental amalgam and other environmental sources can select for mercury resistant bacteria and that this can lead to an increase in resistance to antibiotics. To understand more about this linkage we have investigated the genetic basis for mercury and antibiotic resistance in a variety of oral bacteria. In this study we have cloned and sequenced the mer operon from an Enterococcus faecium strain which was resistant to mercury, tetracycline, and streptomycin. This strain was isolated, in a previous investigation, from a cynomolgus monkey post-installation of amalgam fillings. The mer operon was contained within a putative transposon (Tnmer1) of the ISL3 family. This element was located on a streptomycin resistant plasmid, pPPM1000, which shares homology with pRE25.

Amino Acid Sequence↗

PubMed1996

Stature and seat position as factors affecting fractionated response time in motor vehicle drivers.

Motor vehicle accident fatalities are a cause for concern internationally; all drivers need to selectively attend to environmental changes, and to react swiftly and appropriately. The focus of the present paper was to investigate the effect of stature and seat positioning on fractionated response time. Eighty four young South African adults spanning a range of statures from 1.48 m to 2.00 m were tested in two extreme seat positions (near and far) using a European designed car-shell. Significant differences (p < 0.05) in knee flexion angle, but not in reaction or movement times were identified. Separation of tallest (X 1.93 m) and shortest (X 1.56 m) subjects (n = 20) revealed no significant stature-related differences in response times. However, the tall group showed significantly improved results when seated in the far position and the short group when seated in the near position. The results indicate that correct seat positioning will exert a significant effect on the overall response time of the driver, which in turn will affect the braking distance whilst driving.

Journal Article↗