base. We also found that both cell proliferation and apoptosis were suppressed by cold treatment implying an extension of cell life span after cold acclimation. These results suggest that gill ionocytes may extend their lifespan by delaying natural cell death, and gills may sustain their functions by yielding mature ionocytes from preexisting undifferentiated progenitors. Hence, our studies on gill transcriptome provide new insights into the cellular physiological mechanisms of survival and growth of ectothermic vertebrates in low-temperature environments. doi:10.1016/j.cbpc.2008.10.016 POST-GENOMIC AND DISCOVERY-DRIVEN APPROACHES TO ABIOTIC ENVIRONMENTAL STRESS ADAPTATION IN FISH Andrew R. Cossins a , Lynne U. Sneddon a , Andrew Y. Gracey b a School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, UK b Marine Environmental Biology, University of Southern California, Los Angeles, CA 9089, USA E-mail: cossins@liverpool.ac.uk Abiotic environmental fluctuations of temperature, oxygen, ecotoxicants etc present particular challenges to aquatic animals, yet our understanding of the underpinning mechanisms is incomplete and fragmentary. We have adopted a post-genomics, open-screening approach to understand better the nature of effects of environmental stress upon fish, and also to identify the underlying adaptive responses which mitigate these effects. We first developed a large-scale cDNA microarray containing ∼ 13,500 carp-specific DNA probes each of which was sequenced, identified by homology searching and then functionally annotated using a gene ontology (GO) nomenclature. Whilst this approach is technically sophisticated and requires substantial funding to create the necessary resources, new techniques and the increasing availability of sequence data in databases make this much less constrained by funding, and we have recently constructed microarrays for a range of teleost species. We have also developed the informatic pipelines for sequence analysis and functional annotation of probes, the statistical analysis of large array experiments and ontological definition of lists of responding gene using unbiased techniques. In our first major experiment, a screen of 7 tissues from animals subjected to cold exposure has generated lists of ∼ 3000 responding genes, ∼ 1700 of which were identified from homology searching. These were organised into 24 clusters displaying highly tissue-specific responses, and characterisation of these has defined metabolic pathways that are coherently regulated by cold in all major organs. These lists contain several new candidate genes and gene families for subsequent functional analysis that is underway. A second, larger experiment was focused on hypoxia exposure, and we have processed ∼ 600 arrays from 5 different tissues. This has similarly identified suites of gene responses, including a surprising expression of myoglobin in non-muscle tissues such as liver, gill, brain and intestine. The expression of the corresponding gene product has been confirmed by proteomic determination, and the myoglobin has been immunohistologically localised to specific cells in these tissues. A third microarray experiment using trout has focused on the understanding of behavioural phenotypes, comparing the expression of brain genes in fish that have defined dominant or sub-dominant status within a single dominance hierarchy. This experiment used a limited number of brain genes yet identified 5 genes that displayed highly reproducible differences between dominance groups. We confirmed that one of these corresponded to changed levels of protein, and immunological manipulation of the proteins levels in the brain of zebrafish led to distinctive changes in aggressiveness and dominance properties of individuals. Thus these methods of genome-wide analysis are highly flexible and increasingly powerful, generating mechanistic insights into a range of interesting contrasts through the identification of genes and gene networks that respond to experimental manipulation (Funded by NERC-UK). References Cossins, A.R., Fraser, E.J. & Gracey, A.Y. (2006) Post-genomic approaches to under- standing the mechanisms of environmentally-induced phenotypic plasticity. J. Exp. Biol. 209: 2328–2336. Gracey, A.Y., Fraser, E.J., Li, W., Fang, Y., Brass, A., Rogers, J. and Cossins, A.R. (2004) Coping with cold: an integrative, multi-tissue analysis of transcript expression profiles in a poikilothermic vertebate. Proc. Natl. Acad. Sci. U. S. A. 101: 16970–16975. Fraser, J., Mello, L.V., Fang, Y., Brass, A., Gracey, A.Y. & Cossins, A.R. (2006) Hypoxia- inducible myoglobin expression in non-muscle tissues. Proc. Natl. Acad. Sci. U. S. A. 103: 2977–2981. doi:10.1016/j.cbpc.2008.10.017 THE ROLE OF LEPTIN AND NEUROPEPTIDES IN THE REGULATION OF ENERGY BALANCE DURING LACTATION IN BRANDT'S VOLES (LASIOPODOMYS BRANDTII) Jian-Guo Cui a,b , De-Hua Wang a a State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China b Graduate School of the Chinese Academy of Sciences, Beijing 100049, China E-mail: wangdh@ioz.ac.cn Lactation animals match the high energetic cost by increasing the food intake, mobilizing fat and decreasing the thermogenesis in brown fat. The dramatic metabolic and behavioral changes during lactation are accompanied with lower serum leptin level and changes in hypothalamic neuropeptides expression. The mechanisms responsible for the regulation of energy balance during lactation are still not clear. The aim of the present study was to investigate the possible roles of serum leptin and hypothalamic expression of neuropeptide Y(NPY). Agouti- related protein (AgRP), Proopiomelanocortin (POMC) and Cocaine and ampheta- mine regulated transcript (CART) in Brandt's voles (Lasiopodomys brandtii). Female voles were infused recombinant murine leptinwith different dosages (0.1, 0.2, 0.4 and 0.6 μg day -1 g - 1 ) or PBS (control group) via Alzet mini-osmotic pump during day 10–17 of postpartum. Voles with infusion of leptin significantly increased serum leptin level except at the dosage of 0.1 μg day - 1 g - 1 . Leptin infusion can cause significantly reduction in NPY (P <0.05) and AgRP (P <0.05) mRNA expression and increase in POMC mRNA expression (P < 0.05) in the higher dosage groups, while CART expression was similar in all groups (P > 0.05). Compared with control, food intake significantly decreased (P <0.05) in 0.6 μg day - 1 g -1 dosage group and showed the decreasing trend in other groups. Leptin infusion did not induce voles to mobilize the maternal body fat further and the litter weight gain which represents the reproduction output was unaffected. However, the maternal body mass decreased in leptin infusion group (decreased 6.2–7.8 g, P < 0.01). Decreased maternal body mass can reduce the total energy requirement and favor the growth and survival for pups. These results show that the serum leptin plays important roles in the regulation of energy balance and the feeding behaviordur- ing lactation by altering NPY, AgRP and POMC expression in hypothalamus in Brandt's voles. doi:10.1016/j.cbpc.2008.10.018 GLUCOCORTICOIDS AS SCULPTORS OF ADAPTATION Mary F. Dallman, Norman C. Pecoraro, Susan F. Akana, James P. Warne, Abigail B. Ginsberg, Michelle T. Foster Department of Physiology, UCSF, San Francisco CA USA E-mail: mary.dallman@ucsf.edu Hans Selye coined the terms glucocorticoids (GC), stressor and stress to describe, respectively, the characteristics of adrenal steroid hormones, stimuli and responses that occur when organisms are challenged. In the periphery, stressors, through the actions of GC, mobilize energy stores from muscle and fat and increase gluconeogenetic capacity of the liver, and also increase circulating insulin, thus providing adequate glucose for use by brain and red blood cells, while freeing free fatty acids for use by muscle. Provision of adequate energy sources is only one part of the role of the GC, however. Once provided, the energy must be used through changes in behavior that are also mediated by stressor-induced secretion of these protean hormones. GC feed forward on the brain to affect not only learning and memory, but also to enhance the intensity of behaviors that are determined by the immediate context. Thus, if male rats are in a social dominance–subordinance situation, the steroids increase the level of aggression observed; if wheels are available, rats run more with high GC, and, if palatable food is available, they eat more. These responses are in all likelihood a consequence of the direct actions of the GC on monoaminergic Abstracts 451