The Growth of Infant Mice at Two Temperatures

Barnett, S. A.; Neil, Alexandra C.

doi:10.1530/jrf.0.0290191

Cited by 9 publications

(9 citation statements)

References 6 publications

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“…In other words, the control females presumably secreted milk in proportion to the number of young present, at all litter sizes. This was contrary to expectation based on study of laboratory strains, in which members of large litters tend to be small at weaning (Barnett & Neil, 1972). The pattern of the transferred mice was even more surprising: there was evidence of an effect of litter size, but only at lower sizes: for litters containing two to six members, there was a negative linear regression of weaning weight on litter size (b= -1.…”

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confidence: 80%

House mice bred for many generations in two environments

et al. 1975

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Wild house mice, Mus musculus, were bred in (a) warm (control) and (b) cold laboratory environments. More pairs were barren in the cold than in the warm. Fecund pairs in the cold reared fewer young than controls, but their litters were larger at birth and their young were heavier. Nestling mortality declined over ten generations in the cold. Adult mice in the cold were heavier than controls, but not longer. Mice of the tenth generation in the cold, transferred to the warm environment and bred for three generations, were heavier, fatter and more fertile than the controls, but had lighter heart, stomach and kidneys. The secular changes observed were probably genetically determined, but may have included a maternal component. Summary Wild house mice, Mus musculus L., were trapped, and their descendants reared, in permanently mated pairs, for a number of generations in two laboratory environments, at about 21°C (controls) and ‐3°C, respectively. All mice had sawdust and cottonwool for bedding; but the nests of those at ‐3°C were colder than those in the warm, and fluctuated greatly in temperature. Reproductive performance was inferior in the cold environment: more pairs were barren, and the fecund pairs reared fewer young than the controls. Yet litters at birth were usually larger in the cold, and the young at three weeks were always heavier. Over ten generations nestling mortality declined at ‐3°C. From generation 1 on, adult mice at ‐3°C were heavier than the controls, but there was no corresponding increase in body length. Tails were much shorter relative to body length in the first generations in the cold, but returned to control proportions by generation 10. Most of the structural changes in the cold accord with the “rules” of Bergmann and Allen. The incidence of abnormal sixth lumbar vertebrae was low in all generations at both temperatures. After nine generations, some mice were transferred from the cold to the warm environment, and bred for a further three generations. There they outstripped the controls both in reproductive performance and in growth. They also had more fat, and a heavier and longer small intestine; but the heart, stomach and kidneys were lighter than those of the controls. Adrenal weights at 21°C declined over the generations, but those of the mice at ‐3°C did not. The secular changes observed, especially those in the cold environment, are attributed principally to differential selection of genotypes, not to inbreeding; but maternal effects may also have been involved.

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confidence: 80%

House mice bred for many generations in two environments

et al. 1975

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“…In addition, the difference in mass between CA mice and their controls was more significant at the end of cold adaptation when the mice were 21 days old (control: 8.895 g, CA: 5.668 g, N=6) than at 14 days of age (control: 6.302 g, CA: 4.707 g, N=6). It is known that neonatal mice reared under cold are lower in body mass compared with their controls (Barnett and Neil, 1972). Therefore, these data indicate that the neonates subjected to cold adaptation maintain body temperature at the cost of a gain in body mass.…”

Section: Resultsmentioning

confidence: 77%

“…It is well known that neonates of all species are extremely cold sensitive, and the thermogenic need is the highest during early neonatal development (Barnett and Neil, 1972). Cold adaptation by neonates (including mice pups) is very different from that of adults in the relative extent of recruitment of various physiological responses such as thermogenesis, heterothermy and behavioral adaptations.…”

Section: Introductionmentioning

confidence: 99%

Cold adaptation overrides developmental regulation of sarcolipin expression in mice skeletal muscle: SOS for muscle-based thermogenesis?

Pant

Bal

Periasamy

2015

Journal of Experimental Biology

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Neonatal mice have a greater thermogenic need than adult mice and may require additional means of heat production, other than the established mechanism of brown adipose tissue (BAT). We and others recently discovered a novel mediator of skeletal muscle-based thermogenesis called sarcolipin (SLN) that acts by uncoupling sarcoendoplasmic reticulum Ca 2+ -ATPase (SERCA). In addition, we have shown that SLN expression is downregulated during neonatal development in rats. In this study we probed two questions: (1) is SLN expression developmentally regulated in neonatal mice?; and (2) if so, will cold adaptation override this? Our data show that SLN expression is higher during early neonatal stages and is gradually downregulated in fast twitch skeletal muscles. Interestingly, we demonstrate that cold acclimation of neonatal mice can prevent downregulation of SLN expression. This observation suggests that SLN-mediated thermogenesis can be recruited to a greater extent during extreme physiological need, in addition to BAT.

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“…The only immediate effect of conditions in the nest was that of temperature on growth: at 3 weeks, litters in the warm were consistently heavier than those at -3°C. The different treatments would have had greater effects had the fostered litters been larger: the differential influence on litter weight of environmental temperature is most evident among large litters (Barnett & Neil, 1971), that is, when there is competition for milk (Falconer, 1947;Bateman, 1957;Ashoub, Biggers, McLaren & Michie, 1958) or perhaps for some other aspect of parental attention (Barnett & Burn, 1967).…”

Section: Discussionmentioning

confidence: 99%

Growth and reproduction of mice cross‐fostered between parents reared at different temperatures

Barnett¹,

Neil²

1971

The Journal of Physiology

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SUMMARY1. Litters of mice, Mus mwsculus, of the highly inbred strain A2G/Tb, were reduced to four at birth and cross-fostered within and between three classes: (i) bred at 21°C (controls); (ii) the first generation reared at -3°C ('new stock'); (iii) the seventeenth to twenty-third generations reared at -30 C ('old stock'). There were therefore nine classes of fostered mice.2. There was a higher death rate in the nest and after weaning among mice of new-stock parentage, regardless of foster-parentage. 3. Litters reared at 210 C were heavier at 3 weeks than those reared at -30 C, regardless of parentage; the effect of temperature was also evident in body weights at 16 weeks. There was compensatory growth between 3 and 16 weeks, shown by lower variance in body weight, within classes, at 16 weeks.4. Members of fostered litters were mated, and their reproductive performance recorded to the age of 28 weeks.5. More young were born and weaned per pair at 210 C than at -3°C, regardless of true parentage. In contrast, nestling mortality depended principally on true parentage; there were fewer deaths among the young of mice whose true parents were old stock, regardless of foster-parentage; this effect was especially evident for losses of whole litters.6. Mean body weights of the nine classes of fostered females were positively correlated with mean numbers of young born to them, and with the mean weights of their young at 3 weeks; but there was no such correlation with death rates among their young.7. Young of some of the fostered mice were also mated. The effect of old-stock ancestry on nestling mortality was not evident in this further generation. Some mice were studied after transfer between temperatures without fostering. Their breeding performance confirmed that old-stock mice did not retain their superiority after two generations at 210 C.

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The Growth of Infant Mice at Two Temperatures

Cited by 9 publications

References 6 publications

House mice bred for many generations in two environments

House mice bred for many generations in two environments

Cold adaptation overrides developmental regulation of sarcolipin expression in mice skeletal muscle: SOS for muscle-based thermogenesis?

Growth and reproduction of mice cross‐fostered between parents reared at different temperatures

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