Effect of photoperiod and ambient temperature on nonshivering thermogenesis of Peromyscus maniculatus

Abstract

Table) Deermice were exposed to photoperiods simulating either early winter photoperiod ("winter replicates") or early spring photoperiod ("spring replicates") before experiencing 14-day treatment periods designed to assess the effects of ambient temperature and photoperiod on nonshivering thermogenesis (NST). These treatments consisted of the four combinations of low (5°C) or high (25°C) temperatures and short (8L : 16D) or long (16L : 8D) photoperiod. In both winter and spring replicates, only those mice exposed to both low temperature and short photoperiod experienced significantly elevated levels of NST. In the spring replicates, those mice exposed to both high temperature and long photoperiod experienced significant loss of NST. These results support the hypothesis that photoperiod and ambient temperature interact to trigger changes in NST.

Seasonal variations in thermogenesis and energy requirements of plateau pikas Ochotona curzoniae and root voles Microtus oeconomus

“…The advantage of NST for small mammals is that a great amount of heat can be generated in a short period of time, without interfering with muscular function. Seasonal cycles of BAT and NST have been studied in several small mammal species, including Peromyscus leucopus (Lynch 1973, Zegers andMerritt 1988b), P. maniculatus (Zegers and Merritt 1988b), Microtus ochrogaster (Wunder 1984), Clethrionomys rutilus (Feist and Rosenmann 1976), C. gapperi (Merritt and Zegers 1991), Phodopus sungorus (Heldmaier and Steinlechner 1981), Blarina brevicauda (Merritt 1986), and Sorex cinereus (Merritt 1995). The controlling factors of NST for seasonally acclimatized small mammals were reported by many researchers (Heldmaier et al 1985, Wunder 1985, Feist and Feist 1986, Zegers and Merritt 1988a.…”

Thermal acclimation and non-shivering thermogenesis in three species of South American rodents: a comparison between arid and mesic habitats

“…However Klaus et al (1988) demostrated that this species is able to change its NST capacity by more than 70% through thermal acclimation (5-8)5 ml O 2 /g ) h). Tomasi et al (1987) compared NST values for Peromyscus maniculatus (5)43 ml O 2 /g ) h) with those of Sorex vagrans (13)12 ml O 2 /g ) h), however Zegers & Merritt (1988a) reported a seasonal change that ranged from 4)5 to 10)5 ml O 2 /g ) h for P. maniculatus, and Merritt (1995) reported a seasonal change in NST ranging from 8)02 to 14)6 ml O 2 /g ) h for a congener of S. vagrans, Sorex cinereus. Based on these examples, as well as from many other studies (Feist & Rosenmann, 1976;Zegers & Merritt, 1988b;Klaus et al, 1988;Hayes, 1989;Merritt & Zegers, 1991;McDevitt & Speakman, 1996;Haim, 1996), it is quite clear that fixed values of NST give little information because of the high variations of this feature between seasons or after thermal acclimation.…”

Maximizing survivorship in cold: thermogenic profiles of non-hibernating mammals

“…Animals procured for study resided in a mixed deciduous forest dominated by beech Fagus grandifolia, sugar maple Acer saccharum, yellow poplar Liriodendron tulipifera, and red oak Quercus rubra. Site details and procedures associated with live trapping and processing of small mammals are outlined in Merritt (1986Merritt ( , 1995, Zegers and Merritt (1988), Merritt and Zegers (1991), and Merritt et al (2001b).…”

“…Following metabolic trials, animals were released at the point of capture (Merritt 1986, 1995, Zegers and Merritt 1988, and Merritt and Zegers 1991. This protocol varied for G. volans as they were housed in an outdoor laboratory (single nesters) and outdoor enclosure (group nesters) (Merritt et al 2001b).…”

“…Enhanced NST in cold is well known for small mammals residing in northern environments: for Microtus ochrogaster (Wunder et al 1977), Clethrionomys rutilus (Feist andMorrison 1981, Feist 1984), C. glareolus (Klaus et al 1988), P. leucopus (Lynch and Folk 1971, Lynch 1973, Zegers and Merritt 1988, and P. maniculatus (Zegers and Merritt 1988). In eastern North America, we found that NST in C. gapperi, P. leucopus and P. maniculatus was lowest in summer, increased throughout autumn, peaked in winter and declined through spring.…”