Parr-smolt transformation in Atlantic salmon: thyroid hormone deiodination in liver and brain and endocrine correlates of change in rheotactic behavior

2000 ◽  
Vol 78 (5) ◽  
pp. 696-705 ◽  
Author(s):  
Jennifer L Specker ◽  
J Geoffrey Eales ◽  
Masatomo Tagawa ◽  
William A Tyler, III
Keyword(s):  
Atlantic Salmon ◽  
Activity Ratio ◽  
Condition Factor ◽  
Major Change ◽  
Downstream Migration ◽  
High Ratio ◽  
Natural Photoperiod ◽  
The Brain ◽  
Behavior Condition ◽  
Turbidity Increase

We tested the hypothesis that metabolism of thyroid hormones by the brain of Atlantic salmon (Salmo salar) changes when rheotactic behavior reverses during parr-smolt transformation (PST). We measured brain and liver thyroxine (T4) and 3,5,3'-triiodo-L-thyronine (T3) outer-ring deiodination (ORD) and inner-ring deiodination (IRD) activities and plasma T4 and T3 levels in Atlantic salmon held under natural photoperiod in fresh water at 10°C in the spring of 1993 and 1994. We also measured changes in T4, T3, and cortisol levels during the change in rheotactic behavior. Condition factor decreased while salinity tolerance improved from mid-March to late April. The turbidity-induced transition from upstream to downstream swimming occurred in mid to late April. The main changes in brain deiodination were reduced T3IRD (1993 study) and elevated T4ORD (1994 study). In both years, a high ratio of T4ORD/T3IRD activities in the brain indicated an increased potential for T3 production in the brain during advanced PST. Liver deiodination profiles differed between years, but during advanced PST the low T4ORD activity and low T4ORD/T3IRD activity ratio suggested a low potential for hepatic, and hence systemic, T3 production. However, plasma T4 was increased in downstream swimmers at 1 d (1993) and 4 h (1994) after the turbidity increase. Since at this time brain deiodination pathways were poised towards T3 production, the surge in plasma T4 would likely increase local T3 formation in brain. We conclude that during PST there is no major change in hepatic deiodination and hence probably no major change in systemic T3 availability. But deiodination properties in brain during late PST indicate the potential for local T3 formation. This may be significant when plasma T4 increases at the time of downstream migration.

Physiological and endocrine changes in Atlantic salmon smolts during hatchery rearing, downstream migration, and ocean entry

2013 ◽  
Vol 70 (1) ◽  
pp. 105-118 ◽  
Author(s):  
Stephen D. McCormick ◽  
Timothy F. Sheehan ◽  
Björn Thrandur Björnsson ◽  
Christine Lipsky ◽  
John F. Kocik ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Condition Factor ◽  
Anthropogenic Impacts ◽  
Downstream Migration ◽  
Endocrine Function ◽  
Plasma Growth Hormone ◽  
Data Set ◽  
Hatchery Fish ◽  
Igf I ◽  
Freshwater Habitats

Billions of hatchery salmon smolts are released annually in an attempt to mitigate anthropogenic impacts on freshwater habitats, often with limited success. Mortality of wild and hatchery fish is high during downstream and early ocean migration. To understand changes that occur during migration, we examined physiological and endocrine changes in Atlantic salmon (Salmo salar) smolts during hatchery rearing, downstream migration, and early ocean entry in two successive years. Gill Na+/K+-ATPase activity increased in the hatchery during spring, increased further after river release, and was slightly lower after recapture in the ocean. Plasma growth hormone levels increased in the hatchery, were higher in the river, and increased further in the ocean. Plasma IGF-I remained relatively constant in the hatchery, increased in the river, then decreased in the ocean. Plasma thyroid hormones were variable in the hatchery, but increased in both river- and ocean-captured smolts. Naturally reared fish had lower condition factor, gill NKA activity, and plasma thyroxine than hatchery fish in the river but were similar in the ocean. This novel data set provides a vital first step in understanding the role and norms of endocrine function in smolts and the metrics of successful marine entry.

scholarly journals Kynurenic Acid Metabolism in Various Types of Brain Pathology in HIV-1 Infected Patients

2012 ◽  
Vol 5 ◽  
pp. IJTR.S10627 ◽  
Author(s):  
H. Baran ◽  
J.A. Hainfellner ◽  
B. Kepplinger
Keyword(s):  
Frontal Cortex ◽  
Kynurenic Acid ◽  
Acid Metabolism ◽  
Excitatory Amino Acid ◽  
High Ratio ◽  
Competitive Antagonist ◽  
Kynurenine Aminotransferase ◽  
Cognition Impairment ◽  
The Brain ◽  
Hiv 1

Kynurenic acid, an intermediate metabolite of L-kynurenine, is a competitive antagonist of inotropic excitatory amino acid (EAA) receptors as well as a non competitive antagonist of 7 alpha nicotine cholinergic receptors and its involvement in memory deficit and cognition impairment has been suggested. Alterations of kynurenic acid metabolism in the brain after HIV-1 (human immunodeficiency virus type-1) infection have been demonstrated. The present study evaluates the biosynthetic machinery of kynurenic acid e.g. the content of L-kynurenine and kynurenic acid, as well as the activity of enzymes synthesizing kynurenic acid, kynurenine aminotransferase I (KAT I) and kynurenine aminotransferase II (KAT II) in the frontal cortex and cerebellum of HIV-1 infected patients in relation to different types of pathology classified as follows: HIV in brain (HIV); opportunistic infection (OPP); infarction of brain (INF); malignant lymphoma of brain (LY); and glial dystrophy (GD) and of control (CO) subjects. Of all investigated pathologies the most frequent was OPP (65%), followed by HIV (26%), LY, INF, and GD (each 22%, respectively). Further, 68% of HIV-1 patients had bronchopneumonia, the highest incidence of which, at 60%, was seen in the OPP and LY group. Kynurenic acid was increased significantly in the frontal cortex of LY (392% of CO, P < 0.001), HIV (231% of CO, P < 0.01) and GD (193% of CO, P < 0.05), as well as in the cerebellum of GD (261% of CO, P < 0.01). A significant increase of L-kynurenine was observed in the frontal cortex of LY (385% of CO, P < 0.001) and INF (206% of CO, P < 0.01), and in the cerebellum of GD, LY, OPP and HIV (between 177% and 147% of CO). The KAT I activity increased significantly in the frontal cortex of all pathological subgroups, ie OPP = 420% > INF > LY > HIV > GD = 192% of CO. In the cerebellum, too, all pathological subgroups showed marked increase of KAT I activity (OPP = 320% > LY, HIV > GD > INF = 176% of CO). On contrary, the activity of KAT II was moderately, but significantly, higher in the frontal cortex of INF and OPP; in the cerebellum of HIV, OPP and LY it was comparable to the control, while mildly reduced in INF and GD. Interestingly, normal subjects with the diagnosis of bronchopneumonia were characterized by high kynurenic acid metabolism in the brain, too. Correlation analyses between kynurenine parameters revealed association between high ratio KAT I/KAT II and increased kynurenic acid level and lower L-kynurenine in the frontal cortex and cerebellum of HIV and LY subgroups. The present study revealed a different pattern of alteration of kynurenic acid metabolism in frontal cortex and cerebellum among investigated pathological subgroups of HIV-1 infected patients. Interestingly, a marked enhancement of kynurenic acid metabolism in the brain has been found with occurrence of bronchopneumonia. This finding indicates a notable association between impaired conditions of oxygen availability and enhancement of kynurenic acid formation in the human brain. These observation(s) might have an impact on the understanding of pathological processes in the brain after HIV-1 infection involving the development of neuropsychiatric and neurological symptoms, including memory and cognition impairment.

Multiple changes in the brain of Atlantic salmon, Salmo salar, during photoperiodically-induced parr-smolt transformation

Aquaculture ◽  
1994 ◽  
Vol 121 (1-3) ◽  
pp. 289-290 ◽  
Author(s):  
Pierre-Philippe Morin ◽  
J.Geoffrey Eales ◽  
Toshiaki J Hara ◽  
Svante Winberg ◽  
Göran E Nilsson
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Atlantic Salmon Salmo Salar ◽  
The Brain

17-β Estradiol and 4-nonylphenol delay smolt development and downstream migration in Atlantic salmon, Salmo salar

2004 ◽  
Vol 68 (2) ◽  
pp. 109-120 ◽  
Author(s):  
Steffen S Madsen ◽  
Søren Skovbølling ◽  
Christian Nielsen ◽  
Bodil Korsgaard
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Downstream Migration ◽  
Atlantic Salmon Salmo Salar

Development, survival, and structural alterations of embryos and alevins of Atlantic salmon, Salmo salar L., continuously exposed to alkaline levels of pH, from fertilization

1980 ◽  
Vol 58 (3) ◽  
pp. 369-377 ◽  
Author(s):  
P. G. Daye ◽  
E. T. Garside
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Hydrogen Ions ◽  
Gradual Decline ◽  
Cumulative Mortality ◽  
Zona Radiata ◽  
Atlantic Salmon Salmo Salar ◽  
Branchial Epithelium ◽  
The Brain ◽  
Degree Of Severity

Embryos of the Atlantic salmon, Salmo salar L., were incubated continuously from fertilization at pH 6.8 (control) and pH 9.0 and 9.5, initially at 6.7 °C but with a gradual decline in the first 5 weeks to 5.0 °C for the remaining 10 weeks of exposure. Subsequently, the alevins were maintained in these environments for 50 days after hatching. Developmental processes and hatching were not affected by these levels of pH. Percentage cumulative mortality of treated embryos, 8%, was approximately that in the controls. Alevin mortality in the control lots was 1.2 and 1.3%. At pH 9.0, cumulative mortality was 0.4%, but at pH 9.5 there was an accelerating increase to 18%, at the termination of observation.Sublethal changes in embryos were confined mostly to cell necrosis and sloughed rudimentary epidermis. Some metaplasia of the brain stem occurred at pH 9.5. Sites and intensity of alterations increased in alevins at pH 9.5, following the loss of the zona radiata. In addition to ongoing injury of epidermis, including mucous cells, deleterious alterations occurred in branchial epithelium, erythrocytes, myocardium, blood vessels of the viscera, liver, brain, and optic lenses. In general, sublethal changes caused by hydroxylions are similar to those caused by excessive hydrogen ions but are somewhat less extensive in the structures affected or in their degree of severity.

Winter temperature and food quality affect age at maturity: an experimental test with Atlantic salmon (Salmo salar)

2012 ◽  
Vol 69 (11) ◽  
pp. 1817-1826 ◽  
Author(s):  
Bror Jonsson ◽  
Anders G. Finstad ◽  
Nina Jonsson
Keyword(s):  
Growth Rate ◽  
Atlantic Salmon ◽  
Direct Effect ◽  
Salmo Salar ◽  
Food Quality ◽  
Condition Factor ◽  
Sea Water ◽  
Winter Temperature ◽  
Age At Maturity ◽  
Atlantic Salmon Salmo Salar

Field studies have revealed that many ectotherms mature younger and smaller in warmer environments although they grow faster. This has puzzled ecologists because the direct effect of factors that accelerate growth is expected to be larger, not smaller size. We tested this experimentally for Atlantic salmon (Salmo salar) at two winter temperatures and diets. Logistic regression revealed that the probability of maturation during the second year in sea water, relative to the probability of older maturation, increased with temperature and growth rate during the first winter. Also, large size and high condition factor 1 year prior to maturation stimulated maturation. In females, a high lipid diet increased the probability of maturation as one-sea-winter fish, and there were significant interactions between winter temperature and food quality and between body size and condition factor the first autumn in sea water. Thus, if the direct effect of temperature on growth rate is the main effect of warming, salmon are likely to attain maturity younger and smaller. Also, richer food decreased age at maturation in females. This finding has consequences for interpretations of climate change impacts on age at maturity in Atlantic salmon and may also hold for many other ectotherm species.

Sign in / Sign up

Export Citation Format

Share Document