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PubMedDate not supplied

[DDT and public health].

The availability of DDT led to a revolution in insect pest control. However, in the 1970's it was banned or its use restricted in many countries because it was accumulating in the environment. It was suggested that this could have a deleterious effect on human health. However, these effects, particularly carcinogenesis, have never been clearly proved in humans. Furthermore, accumulation is significantly lower in the tropical than temperature environment. DDT can therefore be continued to be used as a spray in houses, where it is sequestrated by mud walls. It is mainly used against anopheles (mosquitoes) for malaria control and phlebotomus (sand flies) for control of leishmaniasis. However, the value of DDT is restricted by the resistance of many vector species; and its excitatory-repellent effect which does not allow interruption of malaria transmission in highly endemic areas (for example Northern Cameroun).

Animals↗
PubMed1995

Functions of proteins secreted by oviduct epithelial cells.

Studies on embryonic development in vitro as well as observations in vivo, suggested that two aspects of oviduct physiology are important for early development. On one side has to be considered the oviduct "environment": temperature, pH, osmotic pressure, nutrients, oxygen tension, free radical scavengers, etc. On the other, the oviduct "active components": stimulatory and/or regulatory molecules, supposed to finely regulate the fertilisation process and the first differentiative steps. While the physical environment of the oviduct has been under investigation for some decades, studies on oviduct-specific molecules and their functions have only been developed much more recently. The amount of information on this topic, however, has rapidly reached the size that demands a summary. In this review the descriptive literature on oviduct specific proteins will be examined as a basis for illustrating the possible functions of these molecules. In particular their role in fertilisation and early embryonic cleavages will be analysed in some details. Finally a section is devoted to the presence and physiological significance of growth factors in oviduct fluid.

Animals↗
PubMed2002

Temperature-controlled random laser action in liquid crystal infiltrated systems.

We study an amplifying disordered dielectric material of which the scattering strength can be controlled externally via temperature. Such a system was realized by infiltrating liquid crystal and laser dye inside sintered glass powders. The random laser materials that were obtained this way can be brought below or above threshold by small changes in environment temperature, and the bandwidth of its emission can be tuned. We will go into the experimental details and the technical aspects of the realization of these systems, and show measurements on the diffusion constant and spectral properties of the emission.

Journal Article↗
PubMed1982

Responses of the pituitary-adrenal system of mice to an environment of high temperature and humidity.

1. Changes in plasma glucose and corticosterone levels under an environment of high temperature and humidity similar to summers in Japan were investigated. 2. When mice were exposed to high temperature (30-40 degrees C) and humidity (70%), the plasma glucose levels increased with a short-term exposure and decreased with a long-term exposure compared to that of the control mice housed at room temperature (23 degrees C) and humidity (55%). 3. The magnitude of increase of plasma corticosterone levels depended on the degree of ambient temperature and the duration of exposure to the stressful conditions. The plasma corticosterone concentration was highest at 2 hr after initiation of the temperature stress and was reduced at 4 and 6 hr after the treatment: The plasma corticosterone had returned to the control level at 8 hr after the exposure. 4. The dexamethasone treatment inhibited the increase of plasma corticosterone in stress-mice. 5. These results suggest that the response of the plasma corticosterone is a better index than that of glucose for estimation of stress-degree.

Animals↗
PubMed2004

Genetic variation in a cline in a living intertidal snail arose in the Neogastropoda over 100 million years ago.

To understand how species adapt and evolve it is necessary to appreciate the relationship between genetic variation and the environment. Here, the fossil record and molecular data from different lineages of the marine Gastropoda are used to understand the evolution of genetic variations found in the nuclear gene for mitochondrial malate dehydrogenase (mMDH; EC 1.1.1.37) in the living intertidal Muricid snail, Nucella lapillus. Assuming a molecular clock, DNA sequences of mMDH indicate that two variants found in N. lapillus, mMDH(9) and mMDH(10), may have arisen as long as 144 MY (million years) ago and at least prior to the evolution of the Muricidae approximately 112-90 MY ago. The Muricidae contain by far the greatest majority of the Neogastropoda specialized for life in the intertidal habitat. In N. lapillus the mMDH(9) and mMDH(10) variants covary with variations in other biochemically defined loci, inherited phenotypic traits (shell shape and physiology) and karyotype frequencies to differentiate two distinct nuclear haplotypes that are associated with different temperature environments. The variations in shell shape that are associated with the haplotypes of N. lapillus represent adaptations to temperature stress and similar variations occur in other related intertidal molluscs whose lineages are much older than Nucella, which arose around 25 million years ago. It is suggested that the divergence of the mMDH variants found in N. lapillus may reflect an ancient genetic event, such as a chromosomal mutation, perhaps involving variation in other linked traits that together became important in the subsequent evolution of the marine Gastropoda.

Adaptation, Biological↗
PubMed2000

Relative abundance of Archaea and Bacteria along a thermal gradient of a shallow-water hydrothermal vent quantified by rRNA slot-blot hybridization.

Slot-blot hybridization of rRNA with domain-specific oligonucleotide probes targeting the 16S rRNA of Archaea and Bacteria was utilized to assess the relative abundance of these domains along a thermal gradient at a shallow submarine hydrothermal vent near Milos Island (Greece). The highest prokaryotic rRNA concentrations (defined as the sum of bacterial and archaeal rRNA) were found in the uppermost sediment surface (0-20 mm), decreasing strongly with depth. This indicates that the microbial activity was mainly occurring in the surface layer of this hydrothermal vent. Furthermore, rRNA concentrations were higher in regions closer to the vent, suggesting that the hydrothermal activity stimulated microbial activity. Archaea seemed to be a minor component of the microbial community at this vent site, even in the zones with higher temperatures. Bacteria made up at least 78% (mean 95%) of the prokaryotic rRNA. However, along the steepest temperature gradient, the proportion of archaeal rRNA increased. Nevertheless, even in the hottest sediment layer where a quantification was possible (in situ temperature 82 degrees C) archaeal rRNA made up only 11.9% of the prokaryotic rRNA. This suggests that Archaea were generally of minor importance at this vent site and were probably restricted to a narrow niche. The factors that allow Bacteria to dominate in a high temperature environment that was once believed to be the realm of Archaea remain elusive.

Archaea↗
PubMed1976

The influence of short term exposure to two different environmental temperatures on electrolyte concentrations of fowl semen.

The concentration of some of the electrolytes found in fowl semen changed when birds were transferred from a temperature environment of 19 degrees C to either 8 degrees or 30 degrees C. The pH of the semen obtained from males transferred to the 30 degrees C. environment significantly decreased as opposed to a significant increase in the pH of the semen obtained from males transferred to the 8 degrees C. environment. Sodium and potassium concentrations significantly increased in whole semen in both transfer groups, while magnesium increased significantly only in whole semen from males transferred to the 8 degrees C. environment. Sodium increased in seminal plasma when the males transferred from 19 degrees C. environment to the 8 degrees C. environment. The data indicate that an abrupt change to either a warmer or colder environment causes a change in electrolyte concentration of cock semen.

Animals↗
PubMedDate not supplied

Influence of increased environmental temperature on oxidation processes in rat liver mitochondria.

Exposure of rats to elevated temperature of 28 degrees C or 35 degrees C for 3 days six hours daily resulted in a decreased rate of oxidation with succinate or glutamate + malate as substrates, by the mitochondria of liver. The higher decrease was observed in environment temperature of 35 degrees C. There was no change in ADP/O ratio. The activities of NADH: cytochrome c reductase and cytochrome oxidase were stimulated but activities of succinate dehydrogenase and succinate cytochrome reductase were decreased.

Animals↗
PubMed1989

Ontogeny of the lymphoid organs in an Antarctic teleost, Harpagifer antarcticus (Notothenioidei: Perciformes).

The effect of an evolutionary adaptation to low environmental temperature on the development of lymphoid organs was examined in Harpagifer antarcticus from Signy Island (South Orkney Islands; 60 degrees 43'S, 45 degrees 38'W). Thymus, pronephric kidney and spleen were typical, both in position and structural development, of those observed in warmer-water teleosts. The pronephric kidney was the first organ to be infiltrated by leucocytes, at 1 h post-hatch, though the infiltration of the thymic epithelia and the development of the splenic anlage were not observed until 4 weeks post-hatch. Full development of the lymphoid organs was not achieved until the juvenile stage. Although an increased infiltration of the thymus, by subepithelial connective tissues and epithelial mucous cells, occurred in the juvenile and adult stages, there was no evidence of an advanced stage of thymic regression or involution in the adult Harpagifer. Thus, a suppressive influence of the low temperature environment, on the onset and degree of lymphoid organ development and thymic involution, was indicated in this species.

Acclimatization↗
PubMed2002

A high temperature-sensitive mutant of Synechococcus sp. PCC 7002 with modifications in the endogenous plasmid, pAQ1.

To study thermal adaptations in the cyanobacterium, Synechococcus sp. PCC 7002, we screened about 3,000 mutants for their tolerance to high temperature, and found one, SHT1, that is sensitive to high-temperature stress. The mutant had a modified gene construct in the endogenous plasmid, pAQ1. One of the four ORFs, ORF93, was duplicated, and its mRNA level was higher than in the wild type. At 38 degrees C, the growth of SHT1 was retarded as compared with the wild type, and above 38 degrees C, almost all the cells of SHT1 died. This temperature is much lower than that required for induction of heat shock proteins. Interestingly, in both the wild type and SHT1, the thermal stability of oxygen-evolving machinery increased upon acclimation to high temperatures. These findings indicate that the lack of thermal tolerance in the SHT1 strain is likely independent of the adaptation of the PSII complex and heat shock responses, whereas there are essential contributions of genes in the endogenous plasmid to the adaptation to high temperature. Thus, understanding the role of pAQ1 in the adaptation of Synechococcus sp. PCC 7002 to high-temperature environments is the first step in elucidating the function of this plasmid.

Acclimatization↗
PubMed2004

Measurements of OH radicals in a low-power atmospheric inductively coupled plasma by cavity ringdown spectroscopy.

Cavity ringdown spectroscopy is applied to line-of-sight measurements of OH radicals in an atmospheric-pressure argon inductively coupled plasma, operating at low power (200 W) and low gas flows (approximately 18 liters/min). Density populations of the single S21(1) rotational line in the OH A2sigma(+)-X2Pi (0-0) band are extracted from the measured line-of-sight absorbance. Plasma gas kinetic temperatures, derived from the recorded line shapes of the S21(1) line, ranged from 1858 to 2000 K with an average uncertainty of 10%. Assuming local thermodynamic equilibrium, an assumption supported by the comparison of the experimental and simulated spectra, the spatially averaged total OH number density at different observation heights was determined to be in the range of 1.7 x 10(20)-8.5 x 10(20) (m(-3)) with the highest OH density in the plasma tail. This work demonstrates that ringdown spectra of the OH radical may be used both as a thermometer for high-temperature environments and as a diagnostic tool to probe the thermodynamic properties of plasmas.

Argon↗
PubMed1990

A comparative study of the thermal stability of the vertebrate eye lens: Antarctic ice fish to the desert iguana.

We analyzed the thermal stability characteristics of the lenses of 12 vertebrate species in four vertebrate classes. In the selection of animals for comparisons, we controlled for the variable of phylogenetic relatedness by choosing closely-related species that naturally live under very different environmental temperatures, as well as distantly-related species that live under similar environmental temperature regimes. Further, we obtained animals over the range of temperatures in which vertebrates occur, -2 degrees C to 47 degrees C. Experiments in which whole lens transparency was measured under conditions of heat stress showed that animals naturally occurring in high temperature environments have lenses whose transparency is significantly more resistant heating. Studies of behavior of the crystallins during heat stress of the whole lens showed that: (1) a direct correlation exists between the resistance of the lens to thermal insult and both the preferred and maximum body temperature of the animal, (2) some crystallins are more resistant to thermal stress than others, and (3) the taxon-specific crystallins (delta-, tau- and rho- crystallins) were more labile than alpha-, beta- and gamma-crystallins.

Animals↗
PubMed1995

Isolation of a hyperthermophilic archaeum predicted by in situ RNA analysis.

A variety of hyperthermophilic bacteria and archaea have been isolated from high-temperature environments by plating and serial dilutions. However, these techniques allow only the small percentage of organisms able to form colonies, or those that are predominant within environmental samples, to be obtained in pure culture. Recently, in situ 16S ribosomal RNA analyses of samples from the Obsidian hot pool at Yellowstone National Park, Wyoming, revealed a variety of archaeal sequences, which were all different from those of previously isolated species. This suggests substantial diversity of archaea with so far unknown morphological, physiological and biochemical features, which may play an important part within high-temperature ecosystems. Here we describe a procedure to obtain pure cultures of unknown organisms harbouring specific 16S rRNA sequences identified previously within the environment. It combines visual recognition of single cells by phylogenetic staining and cloning by 'optical tweezers'. Our result validates polymerase chain reaction data on the existence of large archael communities.

Archaea↗
PubMed2004

Cold-induced hyperthyroidism produces oxidative damage in rat tissues and increases susceptibility to oxidants.

In this work, we investigated whether cold exposure-induced hyperthyroidism increases oxidative damage and susceptibility to oxidants of rat liver, heart and skeletal muscle. All tissues exhibited gradual increases in hydroperoxide and protein-bound carbonyl levels. Glutathione peroxidase activity increased in all tissues after 2 days and further increased in the muscle after 10 days of cold exposure. Liver glutathione reductase activity increased after 10 days of cold exposure, while heart and muscle activities were not modified. Vitamin E levels were not affected by cold, while coenzyme Q9 and coenzyme Q10 levels decreased in heart and muscle after 2-day cold exposure and were not further modified after 10 days. Liver coenzyme Q9 levels increased after 2 days whereas coenzyme Q10 levels increased after 10 days in the cold. The whole antioxidant capacity was lowered, while parameters positively correlated with susceptibility to oxidants were increased by cold. Lipid fatty acid composition was modified in all tissues. In particular, fatty acid unsaturation degree increased in heart and muscle. Cytochrome oxidase activity increased, suggesting an increased content of hemoproteins, which are able to generate .OH radical. This view was supported by the observation that the tissue susceptibility to H(2)O(2) treatment, which is strongly correlated to iron-ligand content, increased after cold exposure. In this frame, it is apparent that the increase in oxidative capacity, necessary for homeotherm survival in low temperature environments, has potential harmful effects, because it results in increased susceptibility to oxidative challenge.

Animals↗
PubMed1977

Work-heat tolerance of distance runners.

Physical training in a cool environment by subjects not previously trained improves their work-heat tolerance, but can not replace heat acclimatization to the standard heat stress conditions employed by a variety of investigators. This is attributed to the inability of these subjects to sustain prolonged work at high metabolic rates. Thus, they are not maintaining high core body temperatures long enough to bring about an adaptive change to heat. On the other hand, the intense and prolonged (years) training of long distance runners in a temperature environment at high metabolic rates has acclimatized them for at least 4 hours of mild work (MR 160 kcal/m2-hr) in both hot dry (50/27 C db/wb) and hot wet (36.7/33.1 C db/wb) environments, but not for work at high energy expenditures (MR 540 kcal/m2-hr) in a less severe thermal stress (35/21 C db/wb). These highly trained athletes can improve their work-heat tolerance at high metabolic rates in a warm climate by training at competitive speeds in a cool environment dressed in sweat clothing or by training at near competitive speeds in the heat. In either of these situations the athlete is cautioned to consume water at frequent intervals to offset the dehydration associated with excessive sweating under these conditions.

Acclimatization↗
PubMed2005

An anisotropic thermomechanical damage model for concrete at transient elevated temperatures.

The behaviour of concrete at elevated temperatures is important for an assessment of integrity (strength and durability) of structures exposed to a high-temperature environment, in applications such as fire exposure, smelting plants and nuclear installations. In modelling terms, a coupled thermomechanical analysis represents a generalization of the computational mechanics of fracture and damage. Here, we develop a fully coupled anisotropic thermomechanical damage model for concrete under high stress and transient temperature, with emphasis on the adherence of the model to the laws of thermodynamics. Specific analytical results are given, deduced from thermodynamics, of a novel interpretation on specific heat, evolution of entropy and the identification of the complete anisotropic, thermomechanical damage surface. The model is also shown to be stable in a computational sense, and to satisfy the laws of thermodynamics.

Journal Article↗
PubMed2004

[Study on the biological activity of activated sludge using a rapid biological activity tester].

Based on a Rapid Biological Activity Tester (RBAT), a study was taken on the sludge activity which is one of the most important parameters in the operation of aerated biological treating unit in WWTP to measure the effect of the external environmental conditions on the sludge activity, such as acidity and alkalinity, temperature, toxicity, etc. It is observed that the variety of the activity parameters is limited in 20% for a long time. While pH is deviated from the normal value, the biological activity drops to some degree, and furthermore, the ability of the microorganism to endure the acerbic environment is much higher than that to endure the alkaline environment. Temperature increase can result in the enhancement of the biological activity, and if the temperature is higher than 42.5 degrees C, the biological activity is greatly inhibite, but the endogenous respiring rate is less influenced by high temperature. Toxicity can greatly inhibit the biological activity of the activated sludge, and the inhibition is probably selective. Finally, the biological activity of the activated sludge from a real wastewater treatment plant was tested, and the standard deviation of the result is less than 20%. The results indicate that the RBAT is a promising method to measure biological activity, and the characteristics of activated sludge can be well expressed.

Biodegradation, Environmental↗
PubMed1998

In vitro heat effect on heterooligomeric subunit assembly of thermostable indolepyruvate ferredoxin oxidoreductase.

Indolepyruvate ferredoxin oxidoreductase (IOR) from hyperthermophilic archaeon Pyrococcus kodakaraensis KOD1 catalyzes the oxidative decarboxylation of arylpyruvates by forming a heterooligomeric complex (alpha2beta2). The genes iorA and iorB which encode respective alpha and beta subunits, were coexpressed heterologously in Escherichia coli cells under anaerobic conditions. IOR activity was detected from the cell extract containing both subunits and its activity was enhanced by in vitro heat treatment prior to the assay. The iorA and iorB were expressed individually and each subunit was examined for enzymatic activity with and without heat treatment. IOR activity was detected neither from the extract of alpha subunit nor beta subunit. The alpha and beta subunits were mixed and then IOR activity was examined. Weak IOR activity was detected without heat treatment, however, upon heat treatment its activity was enhanced. The mixture of individually heat treated alpha and beta subunits did not possess any IOR activity even though the mixed sample was heat treated again. IOR alpha and beta subunits were individually purified to homogeneity, mixed with or without heat treatment and subunit assembly was examined by determining molecular mass. Upon heat treatment, inactive alpha and beta were converted to an active high molecular weight complex (195 kDa) which corresponds to the alpha2beta2 structure. However, the active complex was not formed without heat treatment, suggesting that high temperature environments are important for the heterooligomerization of IOR subunits.

Base Sequence↗