Performance of mouse lines divergently selected for heat loss when exposed to different environmental temperatures. I. Reproductive performance, pup survival, and metabolic hormones1

Abstract

Mouse populations differing in metabolic rate have been developed through selection for high (MH) and low (ML) heat loss, along with the unselected controls (MC). Objectives of the study were to compare the MH, ML, and MC lines for reproductive performance, pup survival, and metabolic hormones when reared at 12, 22, and 31°C, and to search for line × environment interactions. Conception and litter size were recorded on the parent generation mice introduced to the environments at 11 wk of age and bred after a 3-wk acclimatization period. Survival of pups (preweaning to 3 wk; postweaning from 3 to 9 wk of age) was measured with continuous exposure in the designated environment from birth to the time of measurement. Corticosterone, triiodothyronine (T3), and thyroxine (T4) serum concentrations were measured on the parent generation after producing litters and on the pup generation at 9 wk. No line × environment interaction was detected for conception rate, preweaning mortality,

Performance of mouse lines divergently selected for heat loss when exposed to different environmental temperatures. II. Feed intake, growth, fatness, and body organs1

“…The three rooms that served as the cold (C), normal (N), and hot (H) environmental treatments were kept at 12, 22, and 31°C, respectively. Kgwatalala et al (2004) provides further description of the facilities. Kgwatalala et al (2004) provides a detailed description of the management of the parents and the subsequent pups measured in the present research.…”

“…Kgwatalala et al (2004) provides further description of the facilities. Kgwatalala et al (2004) provides a detailed description of the management of the parents and the subsequent pups measured in the present research. Parents were mated and the dams produced the litters in the three temperature environments.…”

“…The pur-pose of this study was therefore to evaluate whether there are interactions between lines selected for heat loss or metabolic rate and environmental temperatures (12, 22, and 31°C) for growth, feed intake, body fat, and weights of some body organs. Kgwatalala et al (2004) describes the parents of these animals, also measured in the three different thermal temperatures, as well as the experimental animals themselves. Animals came from three independent, unique replicates of three selection lines (MH, ML, MC).…”

Renewed selection for heat loss in mice: Direct responses and correlated responses in feed intake, body weight, litter size, and conception rate1

“…The test for selection response (MH vs. ML) tended toward significance (P = 0.08); there was no evidence for asymmetry of selection response (P = 0.24). Kgwatalala et al (2004) measured conception rate using these same heat loss lines of mice in normal, hot, and cold environments. They did not observe any differences in conception rate due to line or environment × line interaction.…”

A polymorphic glucocorticoid receptor in a mouse population may explain inherited altered stress response and increased anxiety‐type behaviors

“…Frequency of the GR Qn form was much greater in SL line (GR Qn frequencyϭ0.84, GR wt fre-quencyϭ0. 16), whereas frequency of the GR wt form was much higher in SH mice (GR wt frequencyϭ0.91, GR Qn frequencyϭ0.09). The distribution pattern of the two forms of GR suggests an association of GR Qn with low corticosterone response to stress.…”