1. 1.Increased heat tolerance in FHM-cells from Pimephales promelas (Pisces) can be induced by culturing the cells at elevated temperatures (heat resistant acclimation) as well as by heat shock (heat hardening).
2. 2.After shift of culturing temperature (CT) from 16 to 32°C both effects are detectable with different temporal patterns.
3. 3.Cellular concentrations of heat-shock proteins correlate with the hardening effect but not with heat resistance acclimation.
4. 4.Several culturing temperature specific proteins were detected. The patterns of some enzymes are also altered by culturing temperature.
5. 5.Heat resistance acclimation is not caused by selection of a thermoresistant subpopulation of cells.
6. 6.Heat hardening and heat resistance acclimation must be distinguished as different phenomena in FHM-cells.
Author Keywords: Culturing temperature specific proteins; esterase isoenzymes; FHM-cells; heat hardening; heat-shock proteins; heat resistance acclimation; thermotolerance 相似文献
Biannual sampling (March and September) has been carried out over the period 1972 to 1985 at a muddy sand station, 55 m depth, with fauna belonging to the deeper offshore edge of Petersen's Amphiura filiformis community.During the period 1974 to 1980 the community exhibited a high degree of persistence stability. This stability was lost between 1980 and 1983, with rising total numbers and biomass and changes in species ranking. There is some evidence of a downward reversal between 1984–85.Evidence suggests that the principal stabilising process is density dependent mortality mediated by competition in a food limited environment. The principal destabilising process appears to be periodic fluctuations in the organic flux to the bottom. A secondary destabilising process is clearly concerned with fluctuating winter temperature. In competitive terms, cold winters favour increased survival in the dominant species at the expense of the lesser ranked species. This process is, however, more ephemeral and subject to adjustment within the time scale of a year. 相似文献
Caffeine, (1:3:7-tri-methyl-xanthine), either as a prefixation treatment or included with glutaralde-hyde as the primary fixative, destroys or disorganises the microtubules associated with the formation of secondary walls in fibres from the flowering stem of the grass Lolium temulentum L. There is no observable effect of caffeine treatment on the microtubules associated with primary wall formation in collenchyma and young fibres from L. temulentum or in root cap cells of Zea mays L. and Phaseolus vulgaris L. The microtubules associated with primary wall formation are destroyed by cold treatment but not those associated with secondary wall formation. Tannic acid included in the fixative shows the microtubules associated with secondary wall formation in fibres of L. temulentum to be composed of 13 subunits. Treatment with lanthanum hydroxide does not stain the core or the halo of the microtubules.Abbreviation PIPES
Piperazine N-N- bis 2 ethanol sulphonic acid
The Grassland Research Institute is financed through the Agricultural Research Council 相似文献
Although using hourly weather data offers the greatest accuracy for estimating growing degree-day values, daily maximum and
minimum temperature data are often used to estimate these values by approximating the diurnal temperature trends. This paper
presents a new empirical model for estimating the hourly mean temperature. The model describes the diurnal variation using
a sine function from the minimum temperature at sunrise until the maximum temperature is reached, another sine function from
the maximum temperature until sunset, and a square-root function from then until sunrise the next morning. The model was developed
and calibrated using several years of hourly data obtained from five automated weather stations located in California and
representing a wide range of climate conditions. The model was tested against an additional data-set at each location. The
temperature model gave good results, the root-mean-square error being less than 2.0 °C for most years and locations. The comparison
with published models from the literature showed that the model was superior to the other methods. Hourly temperatures from
the model were used to calculate degree-day values. A comparison between degree-day estimates determined from the model and
those obtained other selected methods is presented. The results showed that the model had the best accuracy in general regardless
of the season.
Received: 25 October 2000 / Revised: 2 July 2001 / Accepted: 2 July 2001 相似文献
Oak Mere, the water body studied, is a moderately productive base-poor lowland lake. It has zones of submerged marginal vegetation
growing on sand at the south-west end and on peat at the north-east end. The distributions of L. vespertina and other macroinvertebrates are described in relation to these two distinct areas. Laboratory experiments on behaviour and
survival are described in an attempt to explain the patterns of distribution. The seasonal distribution, variations in population
density, spatial distribution variance in relation to mean density, life cycle, length-weight relationship, growth and biomass
of L. vespertina are then described during two years at the sandy south-west end. The data are used to estimate annual production. Distribution,
life cycle, growth and production are compared with populations in water bodies of lower conductivity in the British Isles
and Scandinavia. 相似文献
Aim The laying of eggs and the building of a nest structure to accommodate them are two of the defining characteristics of members of the class Aves. Nest structures vary considerably across avian taxa and for many species the structure of the completed nest can have important consequences both for parents and their offspring. While nest characteristics are expected to vary adaptively in response to environmental conditions, large‐scale spatial variation in nest characteristics has been largely overlooked. Here, we examine the effects of latitudinal variation in spring temperatures on nest characteristics, including insulatory properties, and reproductive success of blue tits, Cyanistes caeruleus, and great tits, Parus major. Location Great Britain. Methods Nests and reproductive data were collected from seven study sites, spread over 5° of latitude. The nest insulatory properties were then determined before the nests were separated into nest base material and cup lining material. Results As spring temperatures increased with decreasing latitude, the mass of the nest base material did not vary in either species, while the mass of the cup lining material and nest insulatory properties decreased in both species. This suggests that in response to increasing temperatures the breeding female reduces the mass of the cup lining material, thereby maintaining an appropriate microclimate for incubating and brooding. The mean first egg date of both species advanced with decreasing latitude and increasing spring temperatures, although clutch size and brood size at hatching and fledging did not vary. Main conclusions This is the first study to demonstrate that the nest‐construction behaviour of birds varies in response to large‐scale spatial variation in ambient temperatures. Therefore, nest composition reliably indicates environmental conditions and we suggest that studies of nest structure may be sentinels for the early signs of rapid climate change. 相似文献
Studies regarding the thermal ecology of snakes are important to understanding their life histories. Yet, little is known about the thermal ecology of the North American genus Pituophis, which includes the bullsnake (Pituophis catenifer sayi). In an attempt to determine which independent variables significantly affected the thermal ecology of free-ranging bullsnakes, we tracked 12–19 radio-tagged individuals weekly from 2003 to 2005 in Wisconsin (USA) with temperature-sensitive transmitters. Although snake body temperature was found to vary based on several variables treated independently, two separate three-way interactions among variables were significant. We believe our results support the notion that P. c. sayi thermoconforms to environmental conditions in the upper Midwest, but more research on the topic is necessary. 相似文献
The temperature dependence of predation rates is a key issue for understanding and predicting the responses of ecosystems to climate change. Using a simple mechanistic model, we demonstrate that differences in the relative performances of predator and prey can cause strong threshold effects in the temperature dependence of attack rates. Empirical data on the attack rate of northern pike (Esox lucius) feeding on brown trout (Salmo trutta) confirm this result. Attack rates fell sharply below a threshold temperature of +11°C, which corresponded to a shift in relative performance of pike and brown trout with respect to maximum attack and escape swimming speeds. The average attack speed of pike was an order of magnitude lower than the escape speed of brown trout at 5°C, but approximately equal at temperatures above 11°C. Thresholds in the temperature dependence of ecological rates can create tipping points in the responses of ecosystems to increasing temperatures. Thus, identifying thresholds is crucial when predicting future effects of climate warming. 相似文献