- Email: [email protected]
How fish cope with changing environments: Insights from comparative genomics
462
Abstracts
energy turnover, subsequent changes in gene expression and the reorganization of metabolism bring the metabolic machinery in line with the new situation. That is the changes in metabolism are probably a response to, rather than a cause of, the reduction in metabolism. During hypoxia there is an increased production of reactive oxygen species causing DNA damage but this does not lead to an increase in apoptosis in liver cells, in vivo, during hypoxia in common carp (Cyprinus carpio L.). Liver size and cell number of 42-day hypoxic livers, in vivo, were not significantly reduced and there was no increase in cell proliferation. Most of the changes in gene expression occured in the first few days during prolonged hypoxia exposure and these changes included up-regulation of anti-apoptotic genes and down regulation of pro-apoptotic genes. During 42day hypoxia exposure, the level of DNA damage increased at the beginning of the hypoxic period but was reduced in the later periods of exposure, suggesting the repair of DNA damage in carp liver during hypoxia. There were large increases in uncoupling proteins in the liver during hypoxia and these may play a role in reducing production of reactive oxygen species. These changes observed in the liver were not seen in the kidney. This organ appears to rely on increased removal of reactive oxygen species, rather than the down-regulation of production. Some cyprinids can produce ethanol reducing the acidosis associated with lactate production. Fish have a complex set of responses to hypoxia to maintain oxygen uptake, reduce energy turnover and combat the toxic effects of hypoxic exposure. The responses vary with the tissue and with the species in question. doi:10.1016/j.cbpc.2008.10.051
RECOVERY FROM ANAEROBIC INSULTS: DIFFERENTIAL RATES OF RECOVERY FOLLOWING HYPOXIA EXPOSURE AND EXERCISE IN CARP Jeffrey G. Richards Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 E-mail: [email protected] ATP turnover in muscle during high-intensity exercise and exposure to hypoxia is primarily supported by substrate level phosphorylation (creatine phosphate (CrP) hydrolysis and glycolysis), which serves to compensate for metabolic demands that exceed the capacity of mitochondrial oxidative phosphorylation. Although the reasons for the activation of substrate-level phosphorylation during exercise or exposure to hypoxia differ, the end metabolic profiles are similar with low muscle [glycogen] and [CrP] and high [lactate] and metabolic [H+]. The rate of lactate and CrP recovery following exercise was slower that following hypoxia exposure despite being depleted to roughly the same levels. The slower recovery following exercise was due to a greater degree of muscle acidification compared with that induced by hypoxia and this greater tissue H+ accumulation probably limited ATP production during the recovery period. (Supported by NSERC Canada). doi:10.1016/j.cbpc.2008.10.052
EXPLORING THE ACTIONS OF LEPTIN IN FISH Ivar Rønnestad, Tom Ole Nilsen, Sigurd Stefansson, Björn Thrandur Björnsson, Tadahide Kurokawa Department of Biology, University of Bergen, N-5020 Bergen, Norway Fish Endocrinology Laboratory, Department of Zoology/Zoophysiology, Göteborg University, S-40530 Göteborg, Sweden National Research Institute of Aquaculture, Fisheries Research Agency. Mie 516-0193, Nakatsuhama, Nansei, Japan E-mail: [email protected] The recent discovery of leptin in fish in 2005 came in the wake of intense international research since the discovery of leptin in mouse in 1994. Mammalian studies have shown that leptin is a hormone produced by adipose tissue and serves as a key signal for regulating adiposity. Based on the discovery of leptin in fish studies are now under way to elucidate whether the physiological roles of the hormone in ectotherms such as fish
differ from those described in mammals. Understanding the roles of leptin as adiposity signal in fish will have huge ramifications for the understanding of several key physiological processes such as appetite, development, energy balance, growth and puberty among vertebrates. We have selected Atlantic salmon and Atlantic cod as two teleost models to explore the roles of leptin in fish. Cod and salmon are two important species in North-Atlantic fisheries and aquaculture. They have different strategies for energy allocation during growth; Atlantic salmon store excess energy as lipids in the muscle and as visceral fat while Atlantic cod store excess energy in the liver. We will present and discuss data from a study were we used qPCR to quantify the leptin expression in different organs and tissues of starved and fed salmon. doi:10.1016/j.cbpc.2008.10.053
HOW FISH COPE WITH CHANGING ENVIRONMENTS: INSIGHTS FROM COMPARATIVE GENOMICS Patricia M. Schulte Department of Zoology, the University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 E-mail: [email protected] In many fish species there is significant variation among populations in traits associated with behavior, life history, and physiology. This talk will demonstrate how genomics and associated technologies can be used to examine such intra-specific variation. For example, salmon populations of the Bay of Fundy in south eastern Canada have unique life-history characteristics, such as differences in time to maturation, length of migration, ability to spawn over more than one year. By rearing fish from different populations in a common environment, we have been able to use salmonspecific microarrays to detect differences in gene expression among and within these populations, independent of any effects of differences in their natural environments. More than 75 genes demonstrated significant differences in expression between populations, with genes involved in ion homeostasis providing particularly clear differentiation. In addition, more than 50 genes differed in expression between these Canadian wild strains of fish and European fish used for aquaculture. In these comparisons, genes involved in muscle growth and development, and genes involved in the immune system were very clearly differentiated. Knowledge of populationspecific expression profiles will assist with conservation of these endangered populations through an ability to monitor introgression of escaped aquaculture fish, to detect effects of domestication arising during captive rearing, and to determine whether there has been a loss of genes required for optimal performance in the natural environment. doi:10.1016/j.cbpc.2008.10.054
EFFECT OF EPIGALLOCATECHIN 3-GALLATE IN HUMAN NEUROBLASTOMA CELLS EXPOSED TO LEAD Challa Suresha, Mohan C. Vemurib, Chellu S. Chettyc a Department of Biochemistry, National Institute of Nutrition, Hyderabad-500007, India b Department of Surgery, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA c Department of Natural Sciences and Mathematics, Savannah State University, Savannah, GA 31404, USA E-mail: [email protected] It is well known that exposure to lead (Pb) causes altered cognitive function, growth retardation, hyperactivity and biochemical deficiencies mostly associated with the brain function in humans and animals. Several studies have demonstrated that Pb induces oxidative stress and causes damage to the antioxidant defense system of the cells. Earlier studies reported that antioxidants such as epigallocatechin 3-gallate (EGCG), a green tea polyphenol plays a protective role during Pb-exposure. In the present study, human SH-SY5Y neuroblastoma cells were exposed to different concentrations (0.01-10 μM) of Pb for 48 h to determine the concentration
Abstracts
energy turnover, subsequent changes in gene expression and the reorganization of metabolism bring the metabolic machinery in line with the new situation. That is the changes in metabolism are probably a response to, rather than a cause of, the reduction in metabolism. During hypoxia there is an increased production of reactive oxygen species causing DNA damage but this does not lead to an increase in apoptosis in liver cells, in vivo, during hypoxia in common carp (Cyprinus carpio L.). Liver size and cell number of 42-day hypoxic livers, in vivo, were not significantly reduced and there was no increase in cell proliferation. Most of the changes in gene expression occured in the first few days during prolonged hypoxia exposure and these changes included up-regulation of anti-apoptotic genes and down regulation of pro-apoptotic genes. During 42day hypoxia exposure, the level of DNA damage increased at the beginning of the hypoxic period but was reduced in the later periods of exposure, suggesting the repair of DNA damage in carp liver during hypoxia. There were large increases in uncoupling proteins in the liver during hypoxia and these may play a role in reducing production of reactive oxygen species. These changes observed in the liver were not seen in the kidney. This organ appears to rely on increased removal of reactive oxygen species, rather than the down-regulation of production. Some cyprinids can produce ethanol reducing the acidosis associated with lactate production. Fish have a complex set of responses to hypoxia to maintain oxygen uptake, reduce energy turnover and combat the toxic effects of hypoxic exposure. The responses vary with the tissue and with the species in question. doi:10.1016/j.cbpc.2008.10.051
RECOVERY FROM ANAEROBIC INSULTS: DIFFERENTIAL RATES OF RECOVERY FOLLOWING HYPOXIA EXPOSURE AND EXERCISE IN CARP Jeffrey G. Richards Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 E-mail: [email protected] ATP turnover in muscle during high-intensity exercise and exposure to hypoxia is primarily supported by substrate level phosphorylation (creatine phosphate (CrP) hydrolysis and glycolysis), which serves to compensate for metabolic demands that exceed the capacity of mitochondrial oxidative phosphorylation. Although the reasons for the activation of substrate-level phosphorylation during exercise or exposure to hypoxia differ, the end metabolic profiles are similar with low muscle [glycogen] and [CrP] and high [lactate] and metabolic [H+]. The rate of lactate and CrP recovery following exercise was slower that following hypoxia exposure despite being depleted to roughly the same levels. The slower recovery following exercise was due to a greater degree of muscle acidification compared with that induced by hypoxia and this greater tissue H+ accumulation probably limited ATP production during the recovery period. (Supported by NSERC Canada). doi:10.1016/j.cbpc.2008.10.052
EXPLORING THE ACTIONS OF LEPTIN IN FISH Ivar Rønnestad, Tom Ole Nilsen, Sigurd Stefansson, Björn Thrandur Björnsson, Tadahide Kurokawa Department of Biology, University of Bergen, N-5020 Bergen, Norway Fish Endocrinology Laboratory, Department of Zoology/Zoophysiology, Göteborg University, S-40530 Göteborg, Sweden National Research Institute of Aquaculture, Fisheries Research Agency. Mie 516-0193, Nakatsuhama, Nansei, Japan E-mail: [email protected] The recent discovery of leptin in fish in 2005 came in the wake of intense international research since the discovery of leptin in mouse in 1994. Mammalian studies have shown that leptin is a hormone produced by adipose tissue and serves as a key signal for regulating adiposity. Based on the discovery of leptin in fish studies are now under way to elucidate whether the physiological roles of the hormone in ectotherms such as fish
differ from those described in mammals. Understanding the roles of leptin as adiposity signal in fish will have huge ramifications for the understanding of several key physiological processes such as appetite, development, energy balance, growth and puberty among vertebrates. We have selected Atlantic salmon and Atlantic cod as two teleost models to explore the roles of leptin in fish. Cod and salmon are two important species in North-Atlantic fisheries and aquaculture. They have different strategies for energy allocation during growth; Atlantic salmon store excess energy as lipids in the muscle and as visceral fat while Atlantic cod store excess energy in the liver. We will present and discuss data from a study were we used qPCR to quantify the leptin expression in different organs and tissues of starved and fed salmon. doi:10.1016/j.cbpc.2008.10.053
HOW FISH COPE WITH CHANGING ENVIRONMENTS: INSIGHTS FROM COMPARATIVE GENOMICS Patricia M. Schulte Department of Zoology, the University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 E-mail: [email protected] In many fish species there is significant variation among populations in traits associated with behavior, life history, and physiology. This talk will demonstrate how genomics and associated technologies can be used to examine such intra-specific variation. For example, salmon populations of the Bay of Fundy in south eastern Canada have unique life-history characteristics, such as differences in time to maturation, length of migration, ability to spawn over more than one year. By rearing fish from different populations in a common environment, we have been able to use salmonspecific microarrays to detect differences in gene expression among and within these populations, independent of any effects of differences in their natural environments. More than 75 genes demonstrated significant differences in expression between populations, with genes involved in ion homeostasis providing particularly clear differentiation. In addition, more than 50 genes differed in expression between these Canadian wild strains of fish and European fish used for aquaculture. In these comparisons, genes involved in muscle growth and development, and genes involved in the immune system were very clearly differentiated. Knowledge of populationspecific expression profiles will assist with conservation of these endangered populations through an ability to monitor introgression of escaped aquaculture fish, to detect effects of domestication arising during captive rearing, and to determine whether there has been a loss of genes required for optimal performance in the natural environment. doi:10.1016/j.cbpc.2008.10.054
EFFECT OF EPIGALLOCATECHIN 3-GALLATE IN HUMAN NEUROBLASTOMA CELLS EXPOSED TO LEAD Challa Suresha, Mohan C. Vemurib, Chellu S. Chettyc a Department of Biochemistry, National Institute of Nutrition, Hyderabad-500007, India b Department of Surgery, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA c Department of Natural Sciences and Mathematics, Savannah State University, Savannah, GA 31404, USA E-mail: [email protected] It is well known that exposure to lead (Pb) causes altered cognitive function, growth retardation, hyperactivity and biochemical deficiencies mostly associated with the brain function in humans and animals. Several studies have demonstrated that Pb induces oxidative stress and causes damage to the antioxidant defense system of the cells. Earlier studies reported that antioxidants such as epigallocatechin 3-gallate (EGCG), a green tea polyphenol plays a protective role during Pb-exposure. In the present study, human SH-SY5Y neuroblastoma cells were exposed to different concentrations (0.01-10 μM) of Pb for 48 h to determine the concentration