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

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.

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.

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.

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.