The mechanisms of thermogenesis and thermoregulation were studied in the tree shrew (Tupaia belangeri) and greater vole (Eothenomys miletus) of the subtropical region, and Brandt’s vole (Microtus brandti), Mongolian gerbil (Meriones unguiculatus), Daurian ground squirrel (Spermophilus dauricus) and plateau pika (Ochotona curzoniae) of the northern temperate zone. Resting metabolic rate (RMR) and non-shivering thermogenesis (NST) increased significantly in T. belangeri, E. miletus, M. brandti and M. unguiculatus after cold acclimation (4ºC) for 4 weeks. In T. belangeri, the increase in RMR and thermogenesis at liver cellular level were responsible for enhancing the capacity of enduring cold stress, and homeothermia was simultaneously extended. Stable body temperature in M. brandti, E. miletus, M. unguiculatus and O. curzoniae was maintained mainly through increase in NST, brown adipose tissue (BAT) mass and its mitochondrial protein content, and the upregulation of uncoupling protein (UCP1) mRNA, as well as enhancement of the activity of cytochrome C oxidase, α-glycerophosphate oxidase and T4 5′-deiodenase in BAT mitochondria. The RMR in O. curzoniae and euthermic S. dauricus was not changed, while NST significantly increased during cold exposure; the former maintained their stable body temperature and mass, while body temperature in the latter declined by 4.8ºC. The serum T3concentration or ratio of T3/T4 in all the species was enhanced after cold acclimation. Results indicated that: (1) the adaptive mechanisms of T. belangeri residing in the subtropical region to cold are primarily by increasing RMR and secondly by increasing NST, and the mechanisms of thermogenesis are similar to those in tropical mammals; (2) in small mammals residing in northern regions, the adaptation to cold is chiefly to increase NST; (3) the mechanism of cold-induced thermogenesis in E. miletus residing in subtropical and high mountain regions is similar to that in the north; (4) a low RMR in warm environments and peak RMR and NST in cold environments enabled M. unguiculatus to tolerate a semi-desert climate; (5) O. curzoniae has unusually high RMR and high NST, acting mainly via increasing NST to adapt to extreme cold of the Qinghai-Tibet Plateau; (6) the adaptation of euthermic S. dauricus to cold is due to an increase in NST and a relaxed homeothermia; and lastly (7) the thyroid hormone is involved in the regulation of cold adaptive thermogenesis in all the species studied. © 2001 Elsevier Science Inc. All rights reserved.

We studied the effect of dietary vitamin C on growth, liver vitamin C and serum cortisol levels in stressed and unstressed juvenile soft-shelled turtles. Turtles were fed with vitamin C supplementation at dosages of 0, 250, 500, 2500, 5000 or 10 000 mgykg diet for 4weeks. Vitamin C supplementation exerted significant effects on specific growth rate and liver vitamin C concentrations. The specific growth rate peaked in the group fed at 500 mgykg diet, while liver vitamin C levels increased with increasing dietary vitamin C levels. Serum cortisol concentrations did not differ between groups of turtles fed diets supplemented with vitamin C in the range of 0–10 000 mgykg. After acid stress, hepatic vitamin C levels were unaffected, while serum cortisol in the control group was significantly elevated (P-0.01). The other five groups of turtles did not show significant changes in serum cortisol compared with pre-stress levels. © 2003 Elsevier Science Inc. All rights reserved.

The 24-, 48- and 96-h LC50 of nitrite and the effects on reactive oxygen intermediates (ROIs) in haemocytes and muscle, superoxide dismutase (SOD) activity, catalase (CAT) activity, glutathione peroxidase (GPX) activity, in muscle of Macrobrachium nipponense exposed to ambient nitrite were investigated. The 24-, 48- and 96-h LC50 values of nitrite at pH 8.0 were 46, 26 and 13.3 mg l-1. A significantly increased ROIs value was found in prawn (P<0.05) exposed to nitrite shock and increased with increased ambient nitrite concentration. Exposure to a sublethal concentration of nitrite for 24 h, increased ROIs by 97% compared with that of prawn exposed to control nitrite concentration, whereas SOD, CAT and GPX activity decreased 67%, 80.6% and 82.7%, respectively. The results showed that an imbalance between prooxidant forces and antioxidant defenses is one of the toxicity mechanisms of nitrite on prawn.

This paper deals with the developmental process of thermoregulation. From an ecologicalp oint of view, it establishes a mathematical model for postnatal development of thermoregulation, and proposes a new index of homeothermy ability. The model is used to predict homenthermy ability at any time of postnatal development for root vole and other species.

l. Oxygen consumption and body temperatures of 32 juvenile root voles (Microtus oeconomus) of different ages (in days) were measured at ambient temperatures (Ta) of 10, 20 and 30

The mRNA level of uncoupling protein (UCP) specific for brown adipose tissue (BAT) in Daurian ground squirrel, was detected by using a [32P]-labeled oligonucleotide probe. The UCP concentration in mitochondria was indirectly determined by titration with its specific ligand [3H]-labeled GTP. Type II T4 5′-deiodinase of BAT was assayed concomitantly. We found two species of mRNA for UCP with lengths of about 1.9 and 1.5 kb, respectively, both occurring in almost the same concentration. UCP mRNA content was elevated significantly during hibernation, but the UCP concentration did not change compared with that of nonhibernating controls kept at room temperature. When hibernating squirrels were aroused, the UCP mRNA remained at the elevated level as during hibernation, but the UCP concentration increased in comparison with that of nonhibernating controls or during hibernating. Changes in T4 5′-deiodinase activity in BAT were similar to the variations of the UCP mRNA level. These results suggest that the activation of T4 5′-deiodinase in BAT may be an important factor for the up-regulation and maintenance of UCP mRNA content needed for the synthesis of sufficient UCP to acquire the thermogenic capacity for arousal from hibernation. © 1998 Elsevier Science Inc. All rights reserved.

Growth, hemolymph osmolality, tissue water, ribonucleic acid (RNA)/deoxyribonucleic acid (DNA) ratio, protein-bound amino acids and free amino acids (FAA) of Macrobrachium nipponense were investigated, after they were acclimated to 0x, 7x, 14xand 20xfor 14 days. Growth was significantly (P< 0.05) influenced by salinity. The highest weight gain of prawns (P<0.05) was achieved at a salinity of 14x. The RNA/DNA ratio, total protein-bound amino acid (TAA) and FAA concentrations in the muscle of prawns increased by hyperosmotic stress. The osmolality of prawns haemolymph increased slightly in salinities from 0xto14x. A sharp increase in haemolymph osmotic concentration occurs between 14xand 21x, the isosmotic point being reached at 15x (450 mOsm). It is noted that the relationship of total FAA concentration in muscle and salinity in the range of 0–20xrevealed a positive linear correlation. The correlation coefficient (R2) is 0.98. During adaptation, the FAA pool (mainly glycine, alanine and proline) of muscle seems to be directly related to osmoregulation, while the percentage change in alanine in prawns transferred from freshwater to diluted seawater (20x) was most pronounced (116% approx.). These results are compared with those of M. rosenbergii. © 2004 Elsevier B. V. All rights reserved.

We examined the effects of temperature and photoperiod on metabolic thermogenesis and the thermogenic characteristics of brown adipose tissue in plateau pikas (Ochotona curzoniae) and root voles (Microtus oeconomus), the dominant species of small mammals in the alpine meadow ecosystems on the Qinghai-Tibetan Plateau. Pikas and voles were acclimated in the following groups: (1) Long day-warm temperature (16L:8D, 23

Using induction of Fos as an index, we studied cellular activation patterns in the accessory olfactory bulb (AOB) and main olfactory bulb (MOB) of Mandarin voles (Microtus mandarinus (Milne-Edwards, 1871)) following their exposure to beddings soiled by different sexes. Male and female Mandarin voles that were exposed to beddings soiled by the opposite sex produced significantly more Fos-immunoreactive (Fos-ir) neurons in the anterior portion of the AOB and significantly fewer Fos-ir neurons in the posterior portion of the AOB than voles exposed to beddings soiled by the same sex. Furthermore, male and female Mandarin voles exposed to bedding soiled by different sex produced different numbers of Fos-ir cells in MOB. Mandarin voles exposed to beddings soiled by the opposite sex produced significantly more Fos-ir neurons in MOB than voles exposed to beddings soiled by the same sex. Our results establish that Mandarin voles of each sex showed different cellular activation patterns in AOB and MOB following exposures to sex-specific beddings. We suggest that both AOB and MOB were involved in sexual activities induced by chemosensory signals. Resume: En utilisant comme indice l’induction de Fos, nous avons etudie les patrons d’activation cellulaire du bulbe olfactif accessoire (AOB) et du bulbe olfactif principal (MOB) chez des campagnols mandarins (Microtus mandarinus (Milne-Edwards, 1871)) apres une exposition a la litiere souillee des deux sexes. Apres une exposition a la litiere souillee du sexe oppose, les campagnols mandarins males et femelles produisent significativement plus de neurones Fos-positifs dans la portion ante´rieure de leur AOB et significativement moins de neurones Fos-positifs dans la portion poste´rieure que les campagnols exposes a la litiere souillee d’animaux du meme sexe. De plus, les campagnols mandarins males et femelles exposes a la litiere souillee du sexe oppose produisent des nombres differents de cellules Fos-positives dans leur MOB. Les campagnols mandarins exposes a la litiere souillee du sexe oppose produisent significativement plus de neurons Fos-positifs dans leur MOB que les campagnols exposes a la litiere souillee du meme sexe. Nos resultats demontrent que les campagnols mandarins des deux sexes possedent des patrons d’activation cellulaire differents dans leur AOB et leur MOB apres une exposition a la litiere d’un sexe en particulier. Nous croyons que tant le AOB que le MOB sont impliques dans les activites sexuelles induites par les signaux chimiques sensibles.

The effects of kin recognition on estrus and breeding in mandarin voles (Microtus mandarinus) were investigated in the laboratory using a cross-fostering method. Nonsiblings reared apart produced significantly more litters than siblings or nonsiblings reared together. These results may support the hypothesis that familiarity through association before weaning plays an important role in kin recognition. On the other hand, nonsiblings reared apart produced significantly more litters than siblings reared apart. Furthermore, there was no significant difference in number of litters between siblings reared apart and siblings reared together. These observations show that phenotype-matching mechanisms of kin recognition may operate in conjunction with familiarity in kin recognition in this species. Through observing the vaginal cytology of female mandarin voles paired with different males in different rearing conditions, it was found that females paired with familiar males (through association before weaning) produced significantly fewer estrous smears than females paired with unfamiliar males (reared by different parents before weaning), regardless of genetic relatedness. Thus, using vaginal cytology as an indicator of estrus, it was found that familiarity through association before weaning may retard the first estrus of female mandarin voles. Resume: Nous avons etudie les effets que peut avoir le fait de reconnaître les individus apparentes sur l’oestrus et la reproduction chez le campagnol mandarin (Microtus mandarinus) en laboratoire au moyen d’une methode d’adoption croisee. Les campagnols de familles différentes eleves separement produisent significativement plus de portees que les animaux de meme famille eleves ou non ensemble. Ces resultats corroborent l’hypothese selon laquelle la familiarite due aux associations avant le sevrage influence fortement la reconnaissance des individus apparentés. D’autre part, les individus de familles differentes eleves separement produisent significativement plus de portees que les individus de meme famille eleves separement. En outre, il n’y a pas de difference significative entre les campagnols de meme famille eleves separement ou ensemble. Ces observations demontrent que les mecanismes de comparaison des phenotypes impliques dans la reconnaissance des individus apparentes peuvent se conjuguer a la familiarité pour faciliter la reconnaissance des animaux apparentes chez les campagnols de cette espece. L’examen de la cytologie vaginale des femelles de cette espece accouplees a des males differents dans diverses conditions d’elevage a permis de constater que les femelles accouplees a des mâles familiers (associees avant le sevrage) produisent significativement moins de décharges oestrales que les femelles accouplees a des males inconnus (eleves par des parents differents avant le sevrage), quell que soit le lien de parente. Donc, la cytologie vaginale utilisee comme indicateur de l’oestrus demontre que la familiarite acquise par association avant le sevrage peut retarder ou inhiber le premier oestrus chez les femelles du campagnol mandarin.