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Results for “environmental sensitivity”

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PubMed2006

A deficit of detoxification enzymes: pesticide sensitivity and environmental response in the honeybee.

The honeybee genome has substantially fewer protein coding genes ( approximately 11 000 genes) than Drosophila melanogaster ( approximately 13 500) and Anopheles gambiae ( approximately 14 000). Some of the most marked differences occur in three superfamilies encoding xenobiotic detoxifying enzymes. Specifically there are only about half as many glutathione-S-transferases (GSTs), cytochrome P450 monooxygenases (P450s) and carboxyl/cholinesterases (CCEs) in the honeybee. This includes 10-fold or greater shortfalls in the numbers of Delta and Epsilon GSTs and CYP4 P450s, members of which clades have been recurrently associated with insecticide resistance in other species. These shortfalls may contribute to the sensitivity of the honeybee to insecticides. On the other hand there are some recent radiations in CYP6, CYP9 and certain CCE clades in A. mellifera that could be associated with the evolution of the hormonal and chemosensory processes underpinning its highly organized eusociality.

Adaptation, Physiological↗
PubMed2004

[The assessment of the sensitivity of environmental fungi to urea phosphate].

In this paper the authors presented the influence of various urea phosphate doses, 1-12%, on the environmental fungi growth depending on its intensity and the type of created spore e.g. (Penicillium italicum, Aspergillusfumigatus, Aspergillus niger, Cladosporium resinae, Mucor hiemalis i Rhizopus nigricans). The result of urea phosphate effect on fungi was estimated by static culture method using dry mass increase change [g. dry mass/ldm3]. The control was created by the growth of the above mentioned fungi on the basis of urea phosphate free soil. The obtained results were worked out by a statistic method using Duncan's test. The tested fungi showed different sensitivity to the various urea phosphate doses. In the presence of 1% urea phosphate the fungi sensitivity depended on their growth intensity (Aspergillus niger, Mucor hiemalis i Rhizopus nigricans). Additionally, the stimulation of fungi growth with rapid vegetative structure progress was observed. Independently of their physiological properties, significant inhibition of dry mass increase in the range of 3-12% concentration urea phosphate was observed. The result of the use of 3% urea phosphate was the reduction of dry mass growth of all tested fungi.

Antifungal Agents↗
PubMed2002

Mass movements and conservation management in Malta.

Mass movements at an environmentally sensitive but very popular leisure site in Malta were investigated in order to establish whether they were naturally occurring or whether they might in some way have resulted from the chronic long-term degradation of the site. Field surveys of the slopes were undertaken and physical and geotechnical properties of the Maltese Blue Clay Formation, which forms the slopes, were determined from laboratory analysis of samples. Slope stability was analysed using the infinite slope model; analysis of two 1996 mudflows indicates that these mass movements are natural processes. A landslide hazard analysis based on this finding suggested that whilst future mudflows constitute a small hazard, the risk of harm arising from them is even smaller. The implications of this for conservation management of the site are important, given the objective of restoring and then maintaining a natural ecological environment at the site. The mudflows are integral components of this natural environment, shaping the landscape and the ecological communities. The provision of information to visitors constitutes a valuable education and management tool that should further reduce the risk of harm and promote responsible recreational use of the site. However, it is essential that managers understand the nature of all relevant components of an environmentally sensitive site, in order that appropriate management strategies are devised. In the case discussed, these might include avoiding unnecessary future intervention on the clay slopes.

Conservation of Natural Resources↗
PubMed1987

Relative sensitivities of environmental legionellae to selective isolation procedures.

A survey of water samples to determine the efficacy of standard procedures for the isolation of environmental legionellae was conducted. Marked variations in intraspecies resistance to selective agents and treatments were observed, and in experiments with one of the isolates, the response was modified by culture conditions. Five selective procedures incorporating acid (pH 2.2) and heat (50 degrees C, 30 min) treatments, with and without plating on buffered charcoal-yeast extract agar supplemented with vancomycin (5 micrograms/ml), polymyxin B (60 U/ml), and cycloheximide (80 micrograms/ml), caused 5 to 99% decreases in viable counts of pure cultures in water suspensions. The differences in the responses of the cultures to the five treatments were statistically significant. Cells in retained samples of naturally contaminated water from which the original cultures had been isolated were significantly less sensitive than artificially grown isolates. The sensitivities of the laboratory-grown cells to the treatments were affected by the length of incubation on buffered charcoal-yeast extract agar. Whereas acid resistance increased after 24 h of incubation, resistance to the antibiotic mixture decreased.

Analysis of Variance↗
PubMedDate not supplied

Synthesis of thiol-reactive, long-wavelength fluorescent phenoxazine derivatives for biosensor applications.

Two environmentally sensitive, long-wavelength fluorescent phenoxazine derivatives, INR and IANR, were synthesized with linkers for conjugation to the thiol group of cysteine in binding proteins. The linkers were designed based on the attachment sites at two different positions on the phenoxazine, which were chosen in order to study the orientation of the dye with respect to the binding protein. Conjugation of the dyes to the S337C maltose binding protein (MBP) mutant provided conjugates of these dyes that are capable of detecting maltose with different sensitivities. The dye INR gave a 3-fold (+200%) change in fluorescence intensity upon maltose binding when conjugated to S337C MBP with a binding constant (K(d)) of 435 microM. The fluorescence change for IANR was only 20% and the K(d) was 1.4 mM. Conformational analysis of the dyes by molecular modeling suggested that the linker in IANR imparted greater conformational freedom to the dye, resulting in little change in environment between the open and the closed-form conformations. The linker in INR, on the other hand, showed restricted motion, which placed the dye in different environments in the open and closed forms of the protein. Thus, design and placement of the linker play a critical role in the performance of these dyes as environmentally sensitive probes.

Biosensing Techniques↗
PubMed1991

Variation in sensitivity to environmental tobacco smoke among adult non-smokers.

This study evaluated the extent to which acute reactions to environmental tobacco smoke (ETS) among 723 adult non-smokers differ between those who report a medical history indicative of atopy and those with no such history. Study subjects were divided into three risk groups, based on their medical history: people who reported a doctor-confirmed diagnosis of asthma, hay fever, or allergic reactions to pollen, dust, or mites (n = 140); people not in Group I, who reported a doctor-confirmed history of chronic bronchitis, pneumonia, or sinus trouble (n = 246); and all other subjects (n = 337). Reactions to ETS were assessed by asking subjects to report how much it bothers them to be exposed to other people's tobacco smoke and to indicate whether they typically experience symptoms when exposed to ETS. Study findings support the concept that people with a history of atopy or respiratory illness are more sensitive to the acute irritating effects of ETS compared to people without such a medical history.

Acute Disease↗
PubMed2005

Relationship between the energy status of Daphnia magna and its sensitivity to environmental stress.

This work tested the hypothesis that animals with a high energy status are more successful in dealing with stress than animals with a low energy status. Daphnids (Daphnia magna) were reared for 2 weeks in four different concentrations of food. Survival was not affected by food supply, and growth and reproduction increased with increasing food ration. This increase correlated well with the energy status, as was measured by scope for growth on day 15. After 2 weeks, the daphnids in the four different food ration groups were exposed for another 2 weeks to a range of increased salinities or cadmium concentrations, while remaining in their respective food concentrations. In the salinity groups, survival, growth, or reproduction were not influenced at low salinities. Exposure to higher salinity significantly decreased survival and reproduction, but this decrease was more pronounced in the highest food concentrations. In the cadmium exposed daphnids, cadmium content increased with increasing exposure concentrations, but accumulation was independent of food rations. Cadmium exposure significantly decreased survival, growth, and reproduction and this decrease again was more pronounced with increasing food concentration. Thus, the high energy status of the daphnids from the high food concentrations at the start of the exposure did not provide an increased capacity to cope with additional stress. Instead, the sensitivity of the daphnids to stress increased with increasing food ration. This increased sensitivity is likely to be the result of a change in life history from emphasizing survival at low food supply to stressing reproduction at high food supply.

Analysis of Variance↗
PubMed2001

Sensitization to environmental antigens in asthmatic children from a central Italian area.

This study was designed to evaluate the frequency of respiratory allergens in different age groups of asthmatic atopic children in the Chieti-Pescara area. We examined a pediatric population (507 children) aged between 1 to 17 years (mean 6.62 +/- 2.9). All the children were submitted to a panel of skin prick tests (SPT) for 12 common aeroallergens: Grass Pollens (G.), Parietaria (P.), Olive (O.), Artemisia (A.), Ragweed (R.), Dermatophagoides Pteronyssinus and Dermatophagoides Farinae (D.P. & D.F.), Cat and Dog dander (C.D.), Feathers (F.), Alternaria (Al.), Aspergillus (As.). All the subjects gave positive result to one or more allergens. The population was subdivided in to 4 groups according to their age (Group A: 1-3 years; Group B: 4-6 years; Group C: 7-9 years; Group D: 10-17 years). In each age group, we determined the number of subjects with 1, 2, 3, 4 or 5 and more than 5 positive SPT and the prevalence of positive SPT for different allergens. We found that 74% of 507 patients showed positive reaction to Dermatophagoides Pt, 71% to Dermatophagoides Fa, 45% to Grass, 23% to Parietaria, 21% to Olive, 17% to Artemisia, 17% to Cat's or Dog's danders, 13% to Alternaria, 5.9% to Ragweed, 5.9% to Feathers, and 4% to Aspergillus. In addition we detected that 12% of children examined were monosensitized; 56% were sensitized to 2 or 3 allergens; 22% were sensitized to 4 or 5 allergens, and then 8% were polysensitized to > 5 allergens. The allergy to grass pollens and to house dust mites was the most frequent in monosensitized. In the older patients, we found an increase in number of positives SPT to several allergens, and an increase in the frequency of Gr., P. and O. allergy, while the house dust mites sensitization remained constant in all groups and represented the dominant cause of asthmatic symptoms in this population. Our data confirm the importance of age in determining a respiratory polysensitization. In conclusion, our data suggest that house dust mites (D.P. and D.F.) and grass pollens are the most common allergens in asthmatic children of the Chieti-Pescara area.

Adolescent↗
PubMed1998

Vesicular membrane permeability of monomethylarsonic and dimethylarsinic acids.

The transmembrane permeability coefficients of the environmentally sensitive arsenicals, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) have been measured for egg phosphatidylcholine large unilamellar vesicles. The determination of the vesicle concentration-independent first-order rate constants for membrane transport and the permeability coefficients were made using an NMR technique employing shift agents. The permeability coefficient of DMA was found to be two orders of magnitude greater than that of MMA. This is attributed to the presence of MMAs extra hydroxyl group. Both species are shown to permeate membranes in the neutral form. Both the temperature dependence and the dependence on cholesterol content were investigated for DMA. The activation energy and the Arrhenius preexponential factor were found to be dependent on the cholesterol content. A marked increase in both parameters was observed up to 20 mol.% cholesterol, with a further, small increase up to 60%. The significance of these results to our understanding of membrane transport is discussed. The importance of using permeability coefficients rather than n-octanol/water partition coefficients in determining bioavailability and bioaccumulation of environmentally sensitive compounds is also discussed.

Arsenicals↗
PubMed1996

Drug sensitivity and environmental adaptation of mycobacterial cell wall components.

The intrinsic resistance of many mycobacterial species to chemotherapy is largely attributable to their impermeable cell wall. The composition of the cell wall of a particular species appears to be influenced by the environmental niche that the species occupies. The complex regulatory and biosynthetic pathways involved in cell wall biosynthesis and construction offer useful chemotherapeutic targets against mycobacteria.

Adaptation, Physiological↗
PubMed2000

Accelerator mass spectrometry analyses of environmental radionuclides: sensitivity, precision and standardisation

Accelerator Mass Spectrometry (AMS) is the analytical technique of choice for the detection of long-lived radionuclides which cannot be practically analysed with decay counting or conventional mass spectrometry. AMS allows an isotopic sensitivity as low as one part in 10(15) for 14C (5.73 ka), 10Be (1.6 Ma), 26Al (720 ka), 36Cl (301 ka), 41Ca (104 ka), 129I (16 Ma) and other long-lived radionuclides occurring in nature at ultra-trace levels. These radionuclides can be used as tracers and chronometers in many disciplines: geology, archaeology, astrophysics, biomedicine and materials science. Low-level decay counting techniques have been developed in the last 40-50 years to detect the concentration of cosmogenic, radiogenic and anthropogenic radionuclides in a variety of specimens. Radioactivity measurements for long-lived radionuclides are made difficult by low counting rates and in some cases the need for complicated radiochemistry procedures and efficient detectors of soft beta-particles and low energy x-rays. The sensitivity of AMS is unaffected by the half-life of the isotope being measured, since the atoms not the radiations that result from their decay, are counted directly. Hence, the efficiency of AMS in the detection of long-lived radionuclides is 10(6)-10(9) times higher than decay counting and the size of the sample required for analysis is reduced accordingly. For example, 14C is being analysed in samples containing as little as 20 microg carbon. There is also a world-wide effort to use AMS for the analysis of rare nuclides of heavy mass, such as actinides, with important applications in safeguards and nuclear waste disposal. Finally, AMS microprobes are being developed for the in-situ analysis of stable isotopes in geological samples, semiconductors and other materials. Unfortunately, the use of AMS is limited by the expensive accelerator technology required, but there are several attempts to develop compact AMS spectrometers at low (< or = 0.5 MV) terminal voltages. Recent advances in AMS will be reviewed with highlights from the scientific programs at Lucas Heights and other AMS centres.

Journal Article↗
PubMed2003

The distribution of RNA polymerase in Escherichia coli is dynamic and sensitive to environmental cues.

Despite extensive genetic, biochemical and structural studies on Escherichia coli RNA polymerase (RNAP), little is known about its location and distribution in response to environmental changes. To visualize the RNAP by fluorescence microscopy in E. coli under different physiological conditions, we constructed a functional rpoC-gfp gene fusion on the chromosome. We show that, although RNAP is located in the nucleoid and at its periphery, the distribution of RNAP is dynamic and dramatically influenced by cell growth conditions, nutrient starvation and overall transcription activity inside the cell. Moreover, mutational analysis suggests that the stable RNA synthesis plays an important role in nucleoid condensation.

Cell Nucleus↗
PubMed1995

Acid adaptation in Streptococcus mutans UA159 alleviates sensitization to environmental stress due to RecA deficiency.

A RecA-deficient stain of Streptococcus mutans, isolated previously, was found to be more susceptible than the prototroph organism to acid killing and also showed reduced colony-forming ability on sucrose-containing medium. The deficient strain was able to grow in chemostat culture at a low pH value of 5 and did not show reduced capacity to produce acid in standard pH-drop experiments with excess glucose. Moreover, it was able to undergo an adaptive response when grown at a low pH to become more resistant to acid killing and also to killing by ultraviolet radiation or hydrogen peroxide. In fact, after adaptation, it was nearly as resistant as the prototroph strain. These findings were interpreted, in part, in terms of an acid-inducible DNA repair system which functions independently of RecA.

Adaptation, Physiological↗
PubMed1999

Gold--a controversial sensitizer. European Environmental and Contact Dermatitis Research Group.

Until recently, gold allergy was considered to be extremely rare. Gold has been used and worshipped for thousands of years without any obvious complaints of skin problems, either in those participating in mining and other ways of prospecting, or in those wearing jewellery. When studies on contact allergy to gold sodium thiosulfate were published at the beginning of the 1990s, the allergic nature of the reported positive patch test reactions to gold was questioned. The major argument for such questioning was the lack of demonstrable clinical relevance in most positive reactors. A major reason for the questioning may have been confusion in differentiating between contact allergy and allergic contact dermatitis. To arrive at a diagnosis of allergic contact dermatitis, 3 steps have, in principle, to be fulfilled: (i) establishment of contact allergy; (ii) demonstration of present exposure; (iii) assessment of clinical relevance, i.e., causing or aggravating a contact dermatitis. In this paper, these steps are discussed with regard to gold. With our present knowledge of contact allergy-allergic contact dermatitis, we do not recommend including gold sodium thiosulfate in the standard series. It should be applied for scientific purposes and when allergic contact dermatitis from gold is suspected.

Dermatitis, Allergic Contact↗