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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
Molecular Characterization And Expression Of Cytochrome P450 Aromatase In Atlantic Croaker Brain: Regulation By Antioxidant Status And Nitric Oxide Synthase During Hypoxia Stress, Md Saydur Rahman, Peter Thomas
Molecular Characterization And Expression Of Cytochrome P450 Aromatase In Atlantic Croaker Brain: Regulation By Antioxidant Status And Nitric Oxide Synthase During Hypoxia Stress, Md Saydur Rahman, Peter Thomas
School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations
We have previously shown that nitric oxide synthase (NOS, an enzyme) is significantly increased during hypoxic stress in Atlantic croaker brains and modulated by an antioxidant (AOX). However, the influence of NOS and AOX on cytochrome P450 aromatase (AROM, CYP19a1, an enzyme) activity on vertebrate brains during hypoxic stress is largely unknown. In this study, we characterized brain AROM (bAROM, CYP19a1b) cDNA in croaker and examined the interactive effects of hypoxia and a NOS-inhibitor or AOX on AROM activity. The amino acid sequence of croaker bAROM cDNA is highly homologous (76–80%) to other marine teleost bAROM cDNAs. Both real-time PCR …
Molecular Cloning And Characterization Of Two Arnt (Arnt-1 And Arnt-2) Genes In Atlantic Croaker And Their Expression During Coexposure To Hypoxia And Pcb77, Md. Saydur Rahman, Peter Thomas
Molecular Cloning And Characterization Of Two Arnt (Arnt-1 And Arnt-2) Genes In Atlantic Croaker And Their Expression During Coexposure To Hypoxia And Pcb77, Md. Saydur Rahman, Peter Thomas
School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations
Aryl hydrocarbon receptor nuclear translocator (ARNT) is an important transcriptions factor that binds/coactivates drug-metabolizing genes in vertebrates. In this study, we report the cloning and characterization of two ARNT (ARNT-1 and ARNT-2) genes and their mRNA and protein expression in liver tissues of Atlantic croaker after co-exposure to hypoxia and 3,3',4,4'-tetrachlorobiphenyl (PCB77). The full-length croaker ARNT-1 and ARNT-2 genes encode proteins of 537 and 530 amino acids, respectively, and are highly homologous to ARNT-1 and ARNT-2 genes of other vertebrates. ARNT mRNAs are ubiquitously expressed in all tissues. Hypoxia (dissolved oxygen: 1.7 mg/L) exposure (1-4 weeks) did not affect hepatic …
Modeling The Population Effects Of Hypoxia On Atlantic Croaker (Micropogonias Undulatus) In The Northwestern Gulf Of Mexico: Part 1—Model Description And Idealized Hypoxia, Kenneth A. Rose, Sean Creekmore, Peter Thomas, J. Kevin Craig, Md. Saydur Rahman, Rachael Miller Neilan
Modeling The Population Effects Of Hypoxia On Atlantic Croaker (Micropogonias Undulatus) In The Northwestern Gulf Of Mexico: Part 1—Model Description And Idealized Hypoxia, Kenneth A. Rose, Sean Creekmore, Peter Thomas, J. Kevin Craig, Md. Saydur Rahman, Rachael Miller Neilan
School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations
We developed a spatially explicit, individual-based model to analyze how hypoxia effects on reproduction, growth, and mortality of Atlantic croaker in the northwestern Gulf of Mexico lead to population-level responses. The model follows the hourly growth, mortality, reproduction, and movement of individuals on a 300 × 800 spatial grid of 1-km2 cells for 140 years. Chlorophyll-a concentration, water temperature, and dissolved oxygen (DO) were specified daily for each grid cell and repeated for each year of the simulation. A bioenergetics model was used to represent growth, mortality was assumed stage- and age-dependent, and the movement behavior of juveniles and …
Potential And Timescales For Oxygen Depletion In Coastal Upwelling Systems: A Box-Model Analysis, Cheryl S. Harrison, B. Hales, S. Siedlecki, R. M. Samelson
Potential And Timescales For Oxygen Depletion In Coastal Upwelling Systems: A Box-Model Analysis, Cheryl S. Harrison, B. Hales, S. Siedlecki, R. M. Samelson
School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations
A simple box model is used to examine oxygen depletion in an idealized ocean-margin upwelling system. Near-bottom oxygen depletion is controlled by a competition between flushing with oxygenated offshore source waters and respiration of particulate organic matter produced near the surface and retained near the bottom. Upwelling-supplied nutrients are consumed in the surface box, and some surface particles sink to the bottom where they respire, consuming oxygen. Steady states characterize the potential for hypoxic near-bottom oxygen depletion; this potential is greatest for faster sinking rates, and largely independent of production timescales except in that faster production allows faster sinking. Timescales …
Restoration Of Tryptophan Hydroxylase Functions And Serotonin Content In The Atlantic Croaker Hypothalamus By Antioxidant Treatment During Hypoxic Stress, Md. Saydur Rahman, Peter Thomas
Restoration Of Tryptophan Hydroxylase Functions And Serotonin Content In The Atlantic Croaker Hypothalamus By Antioxidant Treatment During Hypoxic Stress, Md. Saydur Rahman, Peter Thomas
School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations
Antioxidants are prototypical scavengers of oxygen-free radicals and have been shown to prevent neuroendocrine dysfunction in vertebrates during oxidative stress. In the present study, we investigated whether antioxidant treatment can reverse hypoxia-induced down-regulation of hypothalamic tryptophan hydroxylase (TPH) and serotonergic functions in Atlantic croaker. Hypothalamic neuronal contents of TPH-1 and TPH-2 proteins, serotonin (5-hydroxytryptamine, 5-HT) and its precursor, 5-hydroxytryptophan (5-HTP) as well as hypothalamic TPH-1 and TPH-2 mRNA expression and TPH activity were measured in croaker after exposure to hypoxia and treatment with pharmacological agents. Multiple injections of N-ethylmaleimide, a sulfhydryl alkylating agent, caused comparable decreases in hypothalamic TPHs functions …
Influence Of Constant And Periodic Experimental Hypoxic Stress On Atlantic Croaker Otolith Chemistry, John Mohan, Md. Saydur Rahman, Peter Thomas, Benjamin Walther
Influence Of Constant And Periodic Experimental Hypoxic Stress On Atlantic Croaker Otolith Chemistry, John Mohan, Md. Saydur Rahman, Peter Thomas, Benjamin Walther
School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations
The chemical composition of fish otoliths may provide information on the environmental exposure histories of fishes if ‘vital effects’ on element incorporation are minimal. In order to use redox-sensitive geochemical proxies, such as manganese, in otoliths to quantify sublethal exposure to hypoxia, the relative influence of endogenous and exogenous controls on otolith composition must first be validated. Controlled laboratory experiments were conducted on Atlantic croaker Micropogonias undulatus to examine the response of otolith Sr:Ca, Ba:Ca, Mg:Ca, Mn:Ca, and Na:Ca ratios to either constant or periodic hypoxia treatments for 4 and 10 wk, respectively. Although fish somatic growth and condition were …
Extensive Reproductive Disruption, Ovarian Masculinization And Aromatase Suppression In Atlantic Croaker In The Northern Gulf Of Mexico Hypoxic Zone, Peter Thomas, Md. Saydur Rahman
Extensive Reproductive Disruption, Ovarian Masculinization And Aromatase Suppression In Atlantic Croaker In The Northern Gulf Of Mexico Hypoxic Zone, Peter Thomas, Md. Saydur Rahman
School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations
The long-term impacts on marine ecosystems of the recent dramatic worldwide increase in the incidence of coastal hypoxia are unknown. Here, we show widespread reproductive disruption in Atlantic croakers collected from hypoxic sites approximately 120 km apart in the extensive northern Gulf of Mexico continental shelf hypoxic zone. Gonadal growth and gamete production were impaired in croakers from hypoxic sites compared with fish from reference normoxic sites east of the Mississippi River Delta. Male germ cells were detected in approximately 19 per cent of croaker ovaries collected in the hypoxic region, but were absent in ovaries from normoxic sites. In …