Brown fat and nonshivering thermogenesis in the gray mouse lemur (<i>Microcebus murinus</i>)

Génin, Fabien; Nibbelink, Maryse; Galand, Matthieu; Perret, Martine; Ambid, L

doi:10.1152/ajpregu.00525.2002

Cited by 36 publications

(25 citation statements)

References 47 publications

(63 reference statements)

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“…The depth of hypothermia and the frequency of torpors were significantly higher in aged animals compared with adult ones. This is likely to result in differences in energy management, and particularly during Tc increase, as also suggested by the increase of basal metabolism described in adult mouse lemurs during the Tc increase following torpor episodes (19). Blood IGF-1 levels varied in aged mouse lemurs after cold exposure, in accordance with modulations observed in adult animals.…”

Section: Discussionsupporting

confidence: 55%

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Effects of age on thermoregulatory responses during cold exposure in a nonhuman primate, Microcebus murinus

Terrien¹,

Zizzari²,

Bluet‐Pajot³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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Cold resistance appears altered with aging. Among existing hypotheses, the impaired capacity in response to cold could be related to an altered regulation of plasma IGF-1 concentration. The combined effects of age and cold exposure were studied in a short-living primate, the gray mouse lemur (Microcebus murinus), which adjusts its energy balance using a daily torpor phase, to avoid high energy cost of normothermia maintenance. Changes in body mass, core temperature, locomotor activity, and caloric intake were monitored under 9-day exposures to 25 degrees C and 12 degrees C in captive animals in winter conditions. Short-term (after 2 days) and long-term (after 9 days) cold-induced changes in IGF-1 levels were also evaluated. In thermoneutral conditions (25 degrees C), general characteristics of the daily rhythm of core temperature were preserved with age. At 12 degrees C, age-related changes were mainly characterized by a deeper hypothermia and an increased frequency of torpor phases, associated with a loss of body mass. A short-term cold-induced decrease in plasma IGF-1 levels was observed. IGF-1 levels returned to basal values after 9 days of cold exposure. No significant effect of age could be evidenced on IGF-1 response. However, IGF-1 levels of cold-exposed aged animals were negatively correlated with the frequency of daily torpor. Responses exhibited by aged mouse lemurs exposed to cold revealed difficulties in the maintenance of normothermia and energy balance and might involve modulations of IGF-1 levels.

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Section: Discussionsupporting

confidence: 55%

“…In captive animals, modulation of the hypothermic phase varies according to photoperiod and Ta (4,6,35,42), food availability (42), and social factors (41). In this primate, the expression of a very robust daily rhythm of Tc involves the use of NST by activation of BAT (19). In this species, age-related physiological changes have been well studied.…”

mentioning

confidence: 99%

Effects of age on thermoregulatory responses during cold exposure in a nonhuman primate, Microcebus murinus

Terrien¹,

Zizzari²,

Bluet‐Pajot³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Thus, the idea that both ecological and biogeographic mechanisms maintain species separation was an implicit assumption of the two-species taxonomy. The two-species classification remained stable until the early 1990s, after which time studies on mouse lemur biology increased sharply (48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58). The discovery that multiple species co-occurred at several localities in the west was one result of this enhanced research activity, thereby yielding an increase in the number of recognized species from two to four (59)(60)(61).…”

Section: Case 4: Adding a Temporal Dimension To Species Diversificatimentioning

confidence: 99%

A multidimensional approach for detecting species patterns in Malagasy vertebrates

Yoder

Olson

Hanley

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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The biodiversity of Madagascar is extraordinarily distinctive, diverse, and endangered. It is therefore urgent that steps be taken to document, describe, interpret, and protect this exceptional biota. As a collaborative group of field and laboratory biologists, we employ a suite of methodological and analytical tools to investigate the vertebrate portion of Madagascar's fauna. Given that species are the fundamental unit of evolution, where microand macroevolutionary forces converge to generate biological diversity, a thorough understanding of species distribution and abundance is critical for understanding the evolutionary, ecological, and biogeographic forces that have shaped Malagasy vertebrate diversity. We illustrate the means by which we apply Mayr's ''three basic tasks'' of the systematist [Mayr, E. (1942) Systematics and the Origin of Species from the Viewpoint of a Zoologist (Harvard Univ. Press, Cambridge, MA)] to identify, classify, and study the organisms that together constitute Madagascar's vertebrate community. Using field inventory methods, specimen-based studies, and morphological and molecular analyses, we formulate hypotheses of species identity that then serve as the foundation for subsequent studies of biology and history. Our experience, as well as that of other investigators, has shown that much of the vertebrate species diversity in Madagascar is ''cryptic'' for both biological and practical reasons. Beyond issues of cryptic biological diversity, the resolution of species identity in Madagascar has been hampered because of a lack of vouchered comparative material at the population level. Through our activities, we are attempting to remedy these limitations while simultaneously enhancing research capacity in Madagascar.The actual demarcation of species taxa uses morphological, geographical, ecological, behavioral, and molecular information to infer the rank of isolated populations.Ernst Mayr (ref. 1, p.276)

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“…During arousal from hibernation, the primary sources of heat generation are skeletal muscle (SM) and brown adipose tissue (BAT; e.g. Carey et al, 2003;Fons et al, 1997;Genin et al 2003 and references therein). For a typical arousal, initial increases in T b appear to be due to heat production in BAT with SM beginning to contribute heat midway through the arousal process (Fons et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

Temporal and temperature effects on the maximum rate of rewarming from hibernation

Utz¹,

Velickovska²,

Shmereva³

et al. 2007

Journal of Thermal Biology

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During hibernation animals oscillate from near ambient (T a ) to euthermic body temperatures (T b ). As animals arouse, the rate of rewarming (RRW) might be expected to simply increase as a function of time. We monitored the T b of golden-mantled ground squirrels (Spermophilus lateralis) housed at 4, 8, 12, and 16° C during natural arousals. The maximum RRW, the time required to reach a maximum RRW, and the relative time index all demonstrated negative relationships with T a . The T b corresponding to maximal RRW demonstrated a positive relationship with T a . Squirrels reached maximal RRW when they had generated 30 to 40% of the heat required to reach a euthermic T b . These data suggest that arousal is more constrained than expected and that both time and temperature influence the RRW.

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Brown fat and nonshivering thermogenesis in the gray mouse lemur (Microcebus murinus)

Cited by 36 publications

References 47 publications

Effects of age on thermoregulatory responses during cold exposure in a nonhuman primate, Microcebus murinus

Effects of age on thermoregulatory responses during cold exposure in a nonhuman primate, Microcebus murinus

A multidimensional approach for detecting species patterns in Malagasy vertebrates

Temporal and temperature effects on the maximum rate of rewarming from hibernation

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