Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology, Jan 29, 2016
The processes of lipid deposition and utilization, via the gene leptin (Lep), are poorly understo... more The processes of lipid deposition and utilization, via the gene leptin (Lep), are poorly understood in taxa with varying degrees of adipose storage. This study examines how these systems may have adapted in marine aquatic environments inhabited by cetaceans. Bowhead (Balaena mysticetus) and beluga whales (Delphinapterus leucas) are ideal study animals-they possess large subcutaneous adipose stores (blubber) and undergo bi-annual migrations concurrent with variations in food availability. To answer long-standing questions regarding how (or if) energy and lipid utilization adapted to aquatic stressors, we quantified variations in gene transcripts critical to lipid metabolism related to season, age, and blubber depth. We predicted leptin tertiary structure conservation and assessed inter-specific variations in Lep transcript numbers between bowheads and other mammals. Our study is the first to identify seasonal and age-related variations in Lep and lipolysis in these cetaceans. While L...
Molecular and Cellular Biochemistry - MOL CELL BIOCHEM, 1996
Binding affinity and binding-pocket polarity is determined for intracellular fatty acid- binding ... more Binding affinity and binding-pocket polarity is determined for intracellular fatty acid- binding protein (FABP) from aerobic muscle of Chaenocephalus aceratus, the Antarctic icefish, and from rat heart. FABPs bind fatty acids via weak-bond forces (both ionic and hydrophobic), and these bond forces are temperature sensitive, yet FABPs are present in animals whose body temperatures range over nearly 40°C. To investigate FABPs sensitivity to body temperature, fatty acid binding affinity (Kd) was determined for both rat heart-FABP and icefish heart-FABP at two physiological temperatures (0°C or 37°C). Saturated and unsaturated fatty acids (16:0 and 16:1), delivered in model membranes (liposomes) whose composition is typical of either Antarctic fish (16:0/22:6 phosphatidylcholine) or mammals (bovine-heart phosphatidylcholine) were examined. Incubation at 0°C or 37°C does not significantly affect Kd for rat heart FABP, regardless of liposome composition or fatty acid ligand (Kd = 0.686 ± ...
Physiological colour change was investigated in the blackspotted rockskipper Entomacrodus striatu... more Physiological colour change was investigated in the blackspotted rockskipper Entomacrodus striatus in Moorea, French Polynesia. Fish colour cycled with significant autocorrelation over the 30 min observation period and was not affected by observation temperature (27 and 31 degrees C). Cycling depended most on dark and yellow pigments (as assayed by separation of colours via software), and therefore, it was hypothesized that short-term cycling was driven by melanophores and xanthophores.
This report provides the first evidence for the existence of two distinct types of fatty acid-bin... more This report provides the first evidence for the existence of two distinct types of fatty acid-binding protein (FABP) in cardiac tissue of vertebrates. Four species of Antarctic teleost fish (Chaenocephalus aceratus, Cryodraco antarcticus, Gobionotothen gibberifrons and Notothenia coriiceps) exhibited two FABP mRNAs of 1. 0 kb and 0.8 kb, which we have termed Hh-FABP and Had-FABP (isolated from Heart tissue, with similarity to mammalian heart-type FABP or mammalian adipose-type FABP respectively). These FABP types appear to be products of distinct genes. Both FABP transcripts were abundant in cardiac and aerobic pectoral muscle. However, relative abundance of the two types varied distinctly among other tissues such as kidney, brain, spleen and white muscle. Neither FABP type was expressed in liver or intestine. The coding regions of Hh-FABP and Had-FABP cDNAs from the same species are only approximately 60% identical with one another. However, homologues of each FABP species, which e...
Cadherins are homophilic cell adhesion molecules that control development of a variety of tissues... more Cadherins are homophilic cell adhesion molecules that control development of a variety of tissues and maintenance of adult structures. In this study, we examined expression of zebrafish cadherin-2 (Cdh2, N-cadherin) and cadherin-4 (Cdh4, R-cadherin) in the visual system of adult zebrafish after eye or optic nerve lesions using immunocytochemistry and immunoblotting. Both Cdh2 and Cdh4 immunoreactivities were specifically up-regulated in regenerating retina and/or the optic pathway. Furthermore, temporal expression patterns of these two cadherins were distinct during the regeneration of the injured tissues. Cadherins have been shown to regulate axonal outgrowth in the developing nervous system, but this is the first report, to our knowledge, of increased cadherin expression associated with axonal regeneration in the vertebrate central nervous system. Our results suggest that both Cdh2 and Cdh4 may be important for regeneration of injured retinal ganglion cell axons.
Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology, Jan 29, 2016
The processes of lipid deposition and utilization, via the gene leptin (Lep), are poorly understo... more The processes of lipid deposition and utilization, via the gene leptin (Lep), are poorly understood in taxa with varying degrees of adipose storage. This study examines how these systems may have adapted in marine aquatic environments inhabited by cetaceans. Bowhead (Balaena mysticetus) and beluga whales (Delphinapterus leucas) are ideal study animals-they possess large subcutaneous adipose stores (blubber) and undergo bi-annual migrations concurrent with variations in food availability. To answer long-standing questions regarding how (or if) energy and lipid utilization adapted to aquatic stressors, we quantified variations in gene transcripts critical to lipid metabolism related to season, age, and blubber depth. We predicted leptin tertiary structure conservation and assessed inter-specific variations in Lep transcript numbers between bowheads and other mammals. Our study is the first to identify seasonal and age-related variations in Lep and lipolysis in these cetaceans. While L...
Molecular and Cellular Biochemistry - MOL CELL BIOCHEM, 1996
Binding affinity and binding-pocket polarity is determined for intracellular fatty acid- binding ... more Binding affinity and binding-pocket polarity is determined for intracellular fatty acid- binding protein (FABP) from aerobic muscle of Chaenocephalus aceratus, the Antarctic icefish, and from rat heart. FABPs bind fatty acids via weak-bond forces (both ionic and hydrophobic), and these bond forces are temperature sensitive, yet FABPs are present in animals whose body temperatures range over nearly 40°C. To investigate FABPs sensitivity to body temperature, fatty acid binding affinity (Kd) was determined for both rat heart-FABP and icefish heart-FABP at two physiological temperatures (0°C or 37°C). Saturated and unsaturated fatty acids (16:0 and 16:1), delivered in model membranes (liposomes) whose composition is typical of either Antarctic fish (16:0/22:6 phosphatidylcholine) or mammals (bovine-heart phosphatidylcholine) were examined. Incubation at 0°C or 37°C does not significantly affect Kd for rat heart FABP, regardless of liposome composition or fatty acid ligand (Kd = 0.686 ± ...
Physiological colour change was investigated in the blackspotted rockskipper Entomacrodus striatu... more Physiological colour change was investigated in the blackspotted rockskipper Entomacrodus striatus in Moorea, French Polynesia. Fish colour cycled with significant autocorrelation over the 30 min observation period and was not affected by observation temperature (27 and 31 degrees C). Cycling depended most on dark and yellow pigments (as assayed by separation of colours via software), and therefore, it was hypothesized that short-term cycling was driven by melanophores and xanthophores.
This report provides the first evidence for the existence of two distinct types of fatty acid-bin... more This report provides the first evidence for the existence of two distinct types of fatty acid-binding protein (FABP) in cardiac tissue of vertebrates. Four species of Antarctic teleost fish (Chaenocephalus aceratus, Cryodraco antarcticus, Gobionotothen gibberifrons and Notothenia coriiceps) exhibited two FABP mRNAs of 1. 0 kb and 0.8 kb, which we have termed Hh-FABP and Had-FABP (isolated from Heart tissue, with similarity to mammalian heart-type FABP or mammalian adipose-type FABP respectively). These FABP types appear to be products of distinct genes. Both FABP transcripts were abundant in cardiac and aerobic pectoral muscle. However, relative abundance of the two types varied distinctly among other tissues such as kidney, brain, spleen and white muscle. Neither FABP type was expressed in liver or intestine. The coding regions of Hh-FABP and Had-FABP cDNAs from the same species are only approximately 60% identical with one another. However, homologues of each FABP species, which e...
Cadherins are homophilic cell adhesion molecules that control development of a variety of tissues... more Cadherins are homophilic cell adhesion molecules that control development of a variety of tissues and maintenance of adult structures. In this study, we examined expression of zebrafish cadherin-2 (Cdh2, N-cadherin) and cadherin-4 (Cdh4, R-cadherin) in the visual system of adult zebrafish after eye or optic nerve lesions using immunocytochemistry and immunoblotting. Both Cdh2 and Cdh4 immunoreactivities were specifically up-regulated in regenerating retina and/or the optic pathway. Furthermore, temporal expression patterns of these two cadherins were distinct during the regeneration of the injured tissues. Cadherins have been shown to regulate axonal outgrowth in the developing nervous system, but this is the first report, to our knowledge, of increased cadherin expression associated with axonal regeneration in the vertebrate central nervous system. Our results suggest that both Cdh2 and Cdh4 may be important for regeneration of injured retinal ganglion cell axons.
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Papers by R. Londraville