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PubMed1987

Indications of an involvement of heat-shock proteins in restoration of repression of temperative-inducible lambda prophage.

Characteristics of lambda c/ts857 prophages that can be attributed to the ability of the temperature-sensitive phage repressor to renature at low temperature are not apparent in host cells that contain a mutation in the htpR gene. Host killing by prophages that are N- or are blocked in DNA synthesis is not prevented by the return of mutant cells to low temperature, and recovery of cells in which the phage remains derepressed is not delayed if the prophage is a mutant that cannot kill. These and other findings suggest that the phage repressor protein is unusually susceptible to inactivation in cells that are unable to respond to heat shock.

Bacteriophage lambda↗
PubMed1988

Displacement of Chernobyl fallout in snow layers of temperate Alpine glaciers.

Measurements of the gross-beta-activity and a gamma-spectrum analysis of radioactive fallout from Chernobyl distributed in vertical snow profiles on an Alpine glacier were carried out. Samples were collected in summer 1986 and in summer 1987. A displacement of isotopes to depths of approximately 6 m was observed. The mean activity per unit area amounts to 10.4 and 6.6 kBq m-2 for samples from 1986 and 1987, respectively, both values corrected to 1 May 1987. Isotopes with half-lives shorter than 110m Ag (250 days) could no longer be detected in 1987.

Accidents↗
PubMed1983

Characteristics of the estrous cycle of the swamp buffalo under temperate conditions.

Estrous cycle, duration of estrus and time of ovulation of eight cyclic buffaloes were examined during a period of one year. Animals were kept under loose-housing conditions and fed according to the Japanese Feeding Standards for dairy cattle. All the animals were observed for the occurrence of estrus twice daily by using a vasectomized bull, and ovarian cycles of each animal were monitored by weekly rectal palpation. Duration of estrus and time of ovulation were determined in 32 estrous periods from eight animals. Animals came in estrus throughout the year. The estrous cycles corresponding to single ovarian cycles ranged from 11 to 38 days with a mode interval of 20 days, averaged 21.5+/-4.7 days. Percentage of the cycles within a range of a mean+/-1 SD (17-26 days) was 79.2%, whereas that of cycles shorter or longer than the expected range was 9.4% and 11.4%, respectively. Estrus took place regardless of the time of day and lasted 9 to 27 hr (19.9+/-4.4 hr). Ovulation occurred 6 to 21 hr (13.9+/-3.4 hr) after the end of estrus, with a mode interval of 12 hr. There were no significant seasonal variations in the estrus characteristics studied.

Journal Article↗
PubMed1994

Climatic sensitivity of temperate forests.

Climatic change and associated global changes are of major interest to foresters, both in terms of forest ecology and of future forest production. Predicting the likely effects of global change on forests is extremely difficult due to the critical lack of information on regional changes in meteorological factors relevant to forests. However, existing models of forest production and forest distribution fail to take adequate account of what is already known. Climate and carbon dioxide concentrations have shown substantial changes over the last 100 years. Although the rate of change is likely to increase, recent proposed and implemented control strategies, together with better climatic models, are tending to suggest that the rate of change will be less than initially thought. This means that past changes may provide an increasingly useful source of information. In particular, information on the impact on forests of both long-term climate change and short-term climatic events is rapidly increasing. Such information should be built into future forest response models.

Journal Article↗
PubMed1994

A coupled carbon-water-energy-vegetation model to assess responses of temperate forest ecosystems to changes in climate and atmospheric CO2. Part I. Model concept.

Predictions of forest ecosystem response to changes in climate and atmospheric CO(2) concentration require hierarchically structured process models. Present forest simulation models have conceptual limitations that restrict their application to climate-change studies. A major drawback of forest succession models is that they often lack physiological details in the simulation of annual tree growth. On the other hand, aggregated ecosystem models assume spatially homogeneous forests, and do not account for successional changes in forest composition and canopy structure. The concept of a new coupled carbon-water-energy-forest vegetation model is presented which attempts to overcome the main limitations of existing models by implementing a modern view of ecological hierarchy and a robust approach for scaling ecological processes in space and time.

Journal Article↗
PubMed1984

Comparative analysis of leucine transport in temperate fish liver in vivo.

The uptake of [14C]leucine in toadfish (Opsanus tau) liver in vivo at 10 degrees C has been studied by a single pulse injection technique. Transport parameters were determined on the basis of the distribution of the amino acid and of [3H]inulin, used as a marker for extracellular space, in liver free and protein-bound fractions and in venous blood draining from the liver. Saturation analysis by the Cornish-Bowden method yielded a maximal uptake of 0.26 mumole, which was similar on a concentration basis to that at 21 degrees C when circulation rate and dilution with blood are taken into account. Isoleucine and phenylalanine competed with leucine uptake at 10 degrees C as at 21 degrees C; additional competitors at 10 degrees C included histidine, methionine and valine. Fish acclimated to 10 degrees C for 2 weeks or more showed a restoration in maximal leucine uptake and disappearance of histidine inhibition. Methionine inhibition was retained. Three transport systems in this species are discussed: 20-20, operating in 20 degrees C-acclimated fish at 20 degrees C; 20-10, in 20 degrees C-acclimated fish at 10 degrees C; and 10-10, in 10 degrees C-acclimated fish at 10 degrees C. The properties of these systems are compared with the 0-0 system of Antarctic fish and with transport systems of mammalian cells. The latter are similar to our non-acclimated system, 20-10, suggesting that the mammalian cell may not be at a state of optimal temperature adaptation.

Acclimatization↗
PubMed1985

Comparison of thermal acclimation effects on the metabolism of Chalcides ocellatus (desert lizard) and Lacerta vivipara (cool-temperate lizard).

The ocellated lizard, Chalcides ocellatus, and the common lizard, Lacerta vivipara, were acclimated to two temperature regimes (10 and 30 degrees C with 12L:12D photoperiod) for 2 weeks. The oxygen consumption rates were measured for both species at temperatures between 5 and 35 degrees C. Cold acclimation was observed in L. vivipara and was in the form of an upward translation of the metabolic rate-temperature curve in comparison to the warm-acclimated lizards (30 degrees C). Chalcides ocellatus showed a response to cold acclimation by decreasing its metabolism only at 10 degrees C.

Acclimatization↗
PubMed1995

The thermal biology of the white-tailed rat Mystromys albicaudatus, a cricetine relic in southern temperate African grassland.

This study examines the hypothesis that Mystromys albicaudatus, a cricetine relic in southern Africa, has thermal characteristics typical of a rodent adapted to a cold temperature regime. Metabolic rate (oxygen consumption) of M. albicaudatus was measured using open-flow respirometry at ambient temperatures ranging from 5 degrees C to 35 degrees C. Lowest specific oxygen consumption was 1.352 +/- 0.089 ml O2 g-1hr-1 (n = 8; body mass = 93.78 +/- 6.27 g) at 25 degrees C, equivalent to 121.8% of the predicted value of Kleiber (1975), 128.8% of the value predicted for eutherians and 113.7% of the value predicted for cricetidae (Hayssen and Lacy, 1985).

Africa↗
PubMed1988

Epidemiology of Ostertagia ostertagi in warm temperate regions of the United States.

For many years our general knowledge on the epidemiology of Ostertagia ostertagi in the U.S.A. was based on research conducted in Scotland and England. During the last 10 years, epidemiologic investigations on O. ostertagi and other gastrointestinal nematodes of cattle have been conducted in various sections of the U.S.A. and Canada. Definite seasonal patterns of O. ostertagi larval inhibition have been demonstrated, but occurrences of the Type I and Type II clinical entities have not been adequately described and associated with the epidemiology of the parasite. All information to the present time suggests that there are seasonal differences in ostertagiasis based on a north and south plane, with larval inhibition occurring during autumn in the north and during spring in the south and parts of the west. Under environmental and management conditions of the south and those other regions where O. ostertagi is significantly and summer is the dominant season, some minimal numbers of inhibition-prone O. ostertagi may be acquired during autumn and winter. However, the early pre-Type II phase (acquisition of inhibition-prone larvae) begins in late winter and reaches peak levels during spring. From January to April, young cattle between weaning and 16 months of age may be affected by Type I disease. Pasture transmission basically ceases from late spring into autumn with consistent high temperature and alternating wet and dry periods. From late summer through autumn (occasionally earlier), Type II disease is possible primarily in yearling cattle and also in older cattle. September and October are months of greatest prevalence. The probability of Type II disease effects occurring, i.e. effects ranging from mild clinical signs and minimal production loss to acute disease and deaths, is dictated by numbers of worms present and characteristics of maturation of inhibited larvae, which in turn may be influenced by current weather factors and management conditions, as well as those of the previous winter and spring.

Animals↗
PubMed1988

The epidemiology of bovine ostertagiasis in the north temperate regions of North America.

Ostertagia ostertagi is widely distributed and is the most pathogenic of the parasitic nematodes affecting cattle in this region. Clinical ostertagiasis is seen mainly in calves and yearlings but outbreaks tend to be sporadic; the subclinical disease is of greater importance. Studies on the population dynamics of the free-living stages have shown that infective larvae can survive on pasture over the relatively severe winter conditions encountered in this region but that such pasture contamination declines during the succeeding grazing season and is lost by midsummer. In the host there is gradual acquisition of worms from pasture over the summer period, with relatively high burdens accumulating in the autumn. A dramatic shift in the proportion of adult to immature worms occurs during the autumn (October). By the time calves are housed, the proportion of larvae (mainly L4) is greater than 80%. This relative distribution of adults to larvae continues through the winter months until early spring when there appears to be a shift to a higher proportion of adults, presumably due to resumption of development of the L4. These persistent L4 stages are considered to be undergoing hypobiosis. Spring infections of calves appear to be mainly acquired from larvae that have successfully overwintered on pasture, and availability of these larvae is drastically reduced by midsummer. There appears to be negligible development of the eggs that result from the spring infections until late summer and early autumn. At this time because of favorable climatic conditions there is rapid larval development which can result in heavy infections in susceptible calves in the autumn.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Adaptative features of ectothermic enzymes--I. Temperature effects on the malate dehydrogenase from a temperate fish Leiostomus xanthurus.

1. Following electrophoresis the s-MDH activity of Leiostomus xanthurus and many other species of fish and amphibian appears in three sharp, equally-spaced, anodal bands. Each band is a dimer (AA, AB and BB) and two loci are active. 2. In Leiostomus tissue extracts A and B subunits are present are differing quantitative levels and their activities can be modified by changes in environment temperature. 3. Thermostability and thermal dependency tests show that, similar to what occurs during acclimatization, the AA isozyme is more stable to heat than is the BB isozyme. The BB isozyme is activated by low temperatures and is rapidly inactivated by high temperatures. 4. Extracts from a variety of fishes, amphibians, reptiles and birds suggest that when only one or two s-MDH bands are present, they behave as dose the AA homodimer in Leiostomus Xanthurus, i.e., are stable at elevated temperatures.

Amphibians↗
PubMed1983

Quantitative protein synthetic rates in various tissues of a temperate fish in vivo by the method of phenylalanine swamping.

1. A single high-dose injection of 14C- (or 3H-) phenylalanine was used for measurement of protein synthetic rates in tissues of toadfish, Opsanus tau, in vivo. 2. Average rates at 20 degrees C, as per cent of tissue protein synthesized per day, were as follows: liver, 14; head kidney, 15; gill, 7.7; spleen 5.0; heart, 2.3; testis, 1.4; epaxial and pectoral muscle, 0.20-0.23. Elevated rates in muscle (0.71%/day) were found in fed fish. 3. Temperature dependency (Q10) in the 10-20 degrees C range averaged 6-7 for tissues with high rates of protein turnover, and 3-4 in heart and muscle after two-weeks acclimation.

Animals↗
PubMed1985

The Society for the Study of Addiction: temperance, treatment or tolerance? (1930-1961).

The purpose of this paper is to describe some of the main themes which highlighted the work of the Society for the Study of Addiction (SSA) in Britain through the years 1930-1961. The major focus of this paper is on alcoholism with special reference to alcoholism treatment. After presenting some general background during this historical period of the Society, three themes will be discussed: visible changes within the treatment framework, sobriety and the argument of strain, and the rise of the alcoholism treatment unit.

Alcoholism↗