Cold acclimation of hamsters was found to result in an increase in cytochrome concentration relative to ATPase activity in brown adipose tissue mitochondria, but not in liver mitochondria. These data lend support to the hypothesis that the uncoupled respiration characteristic of non-shivering thermogenesis is the result of an adaptive change in the composition of brown adipose tissue mitochondr...

A method for the study of the control of the attainment of thermal acclimation has been applied to the crabs, Cancer pagurus and Carcinus maenas. Crabs were heterothermally acclimated by using an anterior-posterior partition between two compartments, one at 8 degrees C and the other at 22 degrees C. One compartment held a three-quarter section of the crab including the central nervous system (C...

Recent progress in the characterization of two groups of genes responsible for natural differences in frost tolerance inwheat and barley is reviewed here. The first group includes the vernalization genes that delay flowering until the end of the winter and protect sensitive floral primordia. This process is regulated mainly by differences in the regulatory regions of VRN1 and VRN3 genes or in t...

Acclimation to heat is a biphasic process involving a transient perturbed phase followed by a long lasting period during which acclimatory homeostasis is developed. In this investigation, we used cDNA stress microarray (Clontech Laboratory) to characterize the stress-related genomic response during the course of heat acclimation and to test the hypotheses that 1) heat acclimation influences the...

UNLABELLED Exercise alone or in combination with environmental heat stress can elevate blood S-100beta protein concentrations. However, the explanatory power of exercise with marked environmental heat stress on the appearance of S-100beta is questionable. It is possible that the process of heat acclimation might afford additional insight. PURPOSE Determine the S-100beta response to moderate-i...

Recent reviews of the adaptive hypotheses for animal responses to acclimation have highlighted the importance of distinguishing between developmental and adult (non-developmental) phenotypic plasticity. There has been little work, however, on separating the effects of developmental plasticity from adult acclimation on physiological traits. Therefore, we investigated the relative contributions o...

The effects of saline or atropine injection (2 mg, im) on eccrine sweating and performance time in seven healthy male subjects were evaluated during treadmill walking (1.34 m X s-1) in a hot-dry environment (Ta = 49 degrees C, Tdp = 20.5 degrees C) before and after heat acclimation (HA). Mean skin temperature (Tsk), rectal temperature (Tre), and heart rate (HR) were continuously measured. Sweat...

We examined if an exercise-heat acclimation program improves body fluid regulatory function in older subjects, as has been reported in younger subjects. Nine older (Old; 70 ± 3 yr) and six younger (Young; 25 ± 3 yr) male subjects participated in the study. Body fluid regulatory responses to an acute thermal dehydration challenge were examined before and after the 6-day acclimation session. Acut...

Low environmental temperatures have a profound effect on biological processes in the body, including the immune system. Cold exposure coincides with hormonal changes, which may directly or indirectly alter the immune system, even in the skeletal muscle. The aim of the present study was to investigate the effect of cold acclimation on immune composition in skeletal muscle. Skeletal muscle biopsi...

The reproductive behaviour of the sexually coercive male eastern mosquitofish (Gambusia holbrooki) offers an excellent model system for testing the benefits of reversible thermal acclimation responses to mating success. We acclimated male mosquitofish to either 18 or 30 degrees C (14 h light:10 h dark) for six weeks and tested their ability to obtain coercive copulations in the presence and the...