scholarly journals EFFECT OF THERMAL SHOCK ON VULNERABILITY TO PREDATION IN JUVENILE SALMONIDS. II. A DOSE RESPONSE BY RAINBOW TROUT TO THREE SHOCK TEMPERATURES.

1972 ◽  
Author(s):  
C.C. Coutant
Keyword(s):  
Rainbow Trout ◽  
Thermal Shock ◽  
Dose Response ◽  
Juvenile Salmonids

Structural requirements for stimulation by thyrotropin-releasing hormone of α-MSH release from rainbow trout (Oncorhynchus mykiss) pituitary fragments in vitro

1994 ◽  
Vol 72 (11) ◽  
pp. 1872-1879 ◽  
Author(s):  
R. Steven Schwartzentruber ◽  
Hubert Vaudry ◽  
Robert J. Omeljaniuk
Keyword(s):  
Biological Activity ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Effective Dose ◽  
Dose Response ◽  
Histidine Residue ◽  
Minimum Effective Dose ◽  
Structural Requirements ◽  
Rainbow Trout Oncorhynchus Mykiss

Juvenile rainbow trout (Oncorhynchus mykiss) pituitary glands were isolated and the neurointermediate lobes (NILs) were removed from the partes distalis. NILs were surgically fragmented, pooled, and superfused in vitro with culture media, then treated with 3-min pulses of native thyrotropin-releasing hormone (TRH) or TRH analog; 10-min fractions were collected and stored (−20 °C) for subsequent analysis of α-melanocyte-stimulating hormone (α-MSH) content by specific radioimmunoassay. After 1–2 h of superfusion, α-MSH release from the NIL remained relatively constant; α-MSH-like immunoreactivity was not detected in eluate from the partes distalis in a series of parallel experiments. Native TRH stimulated acute releases of α-MSH from the NILs with a minimum effective dose of 10−9 M and an estimated ED50 of 1.73 × 10−9 M on the basis of increasing dose–response experiments; decreasing dose–response data provide an estimated minimum effective dose and ED50 of 10−9 and 1.57 × 10−9 M, respectively. No up- or down-regulatory effect was observed when NIL fragments were treated with repeated large (10−6 M) doses of TRH. By comparison, increasing pulse concentrations of pGlu-3-Me-His-Pro-NH2 (MeTRH) stimulated α-MSH release with a minimum effective dose of 10−10 M and an estimated ED50 of 1.56 × 10−9 M. Substitution of the histidine residue with phenylalanine decreased the stimulatory actions of TRH so that the minimum effective dose was 10−6 M. Substitution at either the amino terminus ([Glu1]TRH and [1-Me-(S)-dihydroorotyl1]TRH) or carboxy terminus (pGlu-His and TRH-Gly) resulted in near complete loss of bioactivity. To the best of our knowledge, this is the first investigation of the structural requirements for TRH biological activity in the teleost pituitary. Our data indicate that the structural criteria for TRH stimulation of α-MSH from the teleost pituitary are highly conservative; modification of TRH beyond the methylation of the histidine residue results in massive loss of biological activity. These data are consistent with our previous demonstrations of highly conservative structural requirements for TRH-receptor recognition in the trout pituitary and hypothalamus.

scholarly journals The Rainbow Trout (Oncorhynchus mykiss) Tumor Model: Recent Applications in Low-Dose Exposures to Tumor Initiators and Promoters

2003 ◽  
Vol 31 (1_suppl) ◽  
pp. 58-61 ◽  
Author(s):  
David E. Williams ◽  
George S. Bailey ◽  
Ashok Reddy ◽  
Jerry D. Hendricks ◽  
Aram Oganesian ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Dose Response ◽  
Data Model ◽  
Large Scale ◽  
Tumor Model ◽  
Tumor Promoter ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Tumor Study ◽  
Tumor Studies ◽  
Animal Tumor

The rainbow trout has been utilized as a model for human carcinogenesis for a number of years. Trout are relatively inexpensive to maintain and exhibit (over the 9—12-month tumor assay period) very low spontaneous tumor backgrounds. One of the most powerful applications of this model is the design and conduct of large-scale tumor studies requiring thousands of animals that address statistically challenging questions of dose-response. Two recent examples of such applications include our studies on I3C as a tumor promoter and DBP as a tumor initiator. I3C was shown to promote AFB1- initiated liver cancer at doses near those recommended for supplementation in humans. Further studies are required to determine if the mechanisms responsible for promotion in trout can be extrapolated to humans. In the second example, we report results from the largest animal tumor study ever conducted. A total of 42,000 trout were utilized to measure DBP carcinogenesis down to incidences of 1 in 5,000. The dose response model deviated significantly from linearity although the existence of a threshold could not be statistically established. Extrapolation of the data model predicts a DBP dose producing 1 in 106 cancers that is 1,000-fold higher than predicted by the conservative linear model. If these results can be confirmed with other carcinogens (genotoxic and perhaps nongenotoxic) and other targets, this could have a significant impact on the utilization of animal tumor data in human risk assessment.

scholarly journals The effect of visual isolation on territory size and population density of juvenile rainbow trout (Oncorhynchus mykiss)

2002 ◽  
Vol 59 (2) ◽  
pp. 303-309 ◽  
Author(s):  
I Imre ◽  
J WA Grant ◽  
E R Keeley
Keyword(s):  
Rainbow Trout ◽  
Population Density ◽  
Oncorhynchus Mykiss ◽  
Experimental Tests ◽  
Territory Size ◽  
Control Treatment ◽  
Stream Channels ◽  
Juvenile Salmonids ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Experimental Treatments

Visibility is thought to affect the territory size of visually oriented animals but there have been few experimental tests of the hypothesis. We re-examined the relationship between visibility and territory size in juvenile salmonids to test the hypothesis that increasing habitat heterogeneity results in a reduction in territory size and consequently in higher population densities. Equal densities of young-of-the-year rainbow trout (Oncorhynchus mykiss) were stocked in two experimental treatments with low visibility and a control treatment with high visibility. Visibility was decreased by placing large stones or plywood dividers onto the substrate of experimental stream channels. As predicted, the size of individual territories decreased with decreasing visibility of the habitat. However, the treatments did not differ significantly in population density or growth rate of the fish. While this study confirms the inverse relationship between habitat visibility and territory size, the decrease in territory size did not produce an increase in population density of juvenile salmonids.

A dose / response study with 2,3,7,8 - TCDD in the rainbow trout

Chemosphere ◽  
1990 ◽  
Vol 20 (7-9) ◽  
pp. 1053-1058 ◽  
Author(s):  
Martine E.J. van der Weiden ◽  
Jolanda van der Kolk ◽  
AndréH. Penninks ◽  
Willem Seinen ◽  
Martin van den Berg
Keyword(s):  
Rainbow Trout ◽  
Dose Response ◽  
Dose Response Study

A dose/response study of 2,3,7,8-TCDD in the rainbow trout (Salmo gairdneri)

1989 ◽  
Vol 28 (1-4) ◽  
pp. 509-513 ◽  
Author(s):  
Martine E.J. van der Weiden ◽  
Jolanda van der Kolk ◽  
Willem Seinen ◽  
Martin van den Berg
Keyword(s):  
Rainbow Trout ◽  
Dose Response ◽  
Salmo Gairdneri ◽  
Dose Response Study
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