Metal Binding Activity of the Gills of Rainbow Trout (Oncorhynchus mykiss)

1991 ◽  
Vol 48 (6) ◽  
pp. 1061-1068 ◽  
Author(s):  
Scott D. Reid ◽  
D. G. McDonald
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Metal Binding ◽  
Binding Activity ◽  
Surface Binding ◽  
Apparent Dissociation Constant ◽  
Metal Chemistry ◽  
High Affinity ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Plot Analysis

The objective of this study was to characterize the metal binding of the external gill surface in an attempt to interrelate metal chemistry, gill surface binding activity, and possibly metal toxicity. Individual gill arches from adult rainbow trout (Oncorhynchus mykiss) were exposed to various concentrations of either 140La, 45Ca, 109Cd, or 64Cu. The apparent dissociation constant (KD) and capacity (Bmax) of the external gill surface for the metals was calculated using Scatchard plot analysis. Half-saturation time (t1/2) and binding cooperativity (Hn) were also determined. The KD for gill metal binding ranged from 0.31 ± 0.02 mM for La3+ (high affinity) to 4.3 ± 0.04 mM for Cu2+ (low affinity). The gill binding affinity for Ca2+ was threefold lower than for La3+, but was similar to that for Cd2+. The gills had the lowest affinity for Cu2+, almost 14 times lower than that for La3+. Bmax for La3+ was found to be significantly lower than for any other metal (0.14 ± 0.001 μmol∙g−1), while nearly seven times as much Cu2+ was accumulated by the gills compared with La3+, The Ca2+ and Cd2+Bmax estimates were intermediate.

Bacterial-binding activity and plasma concentration of ladderlectin in rainbow trout (Oncorhynchus mykiss)

2007 ◽  
Vol 23 (2) ◽  
pp. 305-315 ◽  
Author(s):  
Karrie M. Young ◽  
Spencer Russell ◽  
Mackenzie Smith ◽  
Paul Huber ◽  
Vaughn E. Ostland ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Plasma Concentration ◽  
Oncorhynchus Mykiss ◽  
Binding Activity ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Bacterial Binding

Acclimation to hard or soft water at weakly alkaline pH influences gill permeability and gill surface calcium binding in rainbow trout (Oncorhynchus mykiss)

1995 ◽  
Vol 52 (12) ◽  
pp. 2583-2593 ◽  
Author(s):  
Deke T. Gundersen ◽  
Lawrence R. Curtis
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Calcium Binding ◽  
Binding Capacity ◽  
High Hardness ◽  
Alkaline Ph ◽  
Surface Binding ◽  
Weakly Alkaline ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Osmotic Water

Rainbow trout (Oncorhynchus mykiss) were acclimated for 10 d to soft (0.1 mM as CaCO3) or hard (1.0 mM as CaCO3) water at weakly alkaline pH (8.06–8.34). Following acclimation, individual gill arches were removed for examining the effects of low hardness or high hardness acclimation on gill water permeability, gill Ca2+ interactions, and gill aluminum interactions. Isolated gill arches were exposed to water of varying Ca2+ (0.0–1.0 mM) and aluminum (3.7–37 μM) concentration for osmotic permeability experiments. High hardness acclimated gills had significantly greater percent weight gain over time caused by osmotic water entry than low hardness acclimated gills, when exposed to distilled water (32.34 ± 1.15 and 24.86 ± 0.62%, respectively, after 60-min incubations); these differences were absent when Ca2+ (0.1–1.0 mM) was added to the incubation medium. Gill arch Ca2+ binding experiments resolved two gill surface binding site populations, which differed in their Ca2+ binding affinity. The higher affinity sites were probably associated with gill membrane permeability, because low hardness acclimated gills had more such sites (binding capacity, 0.322 ± 0.027 μmol Ca2+∙g−1) and less permeable gills than high hardness acclimated gills (binding capacity, 0.198 ± 0.004 μmol Ca2+∙g−1). Aluminum had little influence on gill permeability and gill Ca2+ binding.

scholarly journals The effects and physiological consequences of raised levels of cortisol on rainbow trout (Oncorhynchus mykiss) erythrocyte beta-adrenoreceptors

1991 ◽  
Vol 158 (1) ◽  
pp. 217-240 ◽  
Author(s):  
S. D. Reid ◽  
S. F. Perry
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Radioreceptor Assay ◽  
Receptor Density ◽  
Surface Receptors ◽  
High Affinity ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Surface Receptor ◽  
Cortisol Levels

We have investigated the influence of cortisol on the beta-adrenoreceptor population of rainbow trout [Oncorhynchus mykiss (Walbaum)] erythrocytes and determined what impact it has on the adrenergic responsiveness of erythrocytes in vitro to exogenous catecholamines. To do so, the erythrocyte beta-adrenoreceptors were characterized in fish with chronically elevated plasma cortisol levels (118 +/− 5.9 ng ml-1, greater than 10 days) and compared with shams, using radioreceptor assay techniques. The number of ‘internalized’, low-affinity receptors was increased when cortisol levels were raised, but the number of high-affinity, ‘surface’ receptors was not altered. The physiological significance of this response was ascertained by assessing the in vitro sensitivity (or responsiveness) of erythrocytes to adrenaline and noradrenaline (10–1000 nmol l-1) under normoxic (PO2 = 16.13 +/− 0.55 kPa, PCO2 = 0.41 +/− 0.01 kPa) or hypoxic (PO2 = 4.13 +/− 0.15 kPa, PCO2 = 0.43 +/− 0.01 kPa) conditions. Erythrocyte sensitivity to catecholamines, as determined by changes in both whole-blood pH (delta pHe) and intracellular cyclic AMP content, was greater in hypoxic than in normoxic blood. Although cortisol further enhanced the responsiveness of erythrocytes to catecholamines, this amplification in sensitivity was observed only during hypoxia. When the radioreceptor assay was conducted using erythrocytes from the catecholamine sensitivity experiments, results were consistent with initial receptor density data. An increase in surface receptor density was associated with hypoxia in vitro. This hypoxia-specific increase in surface beta-adrenoreceptors was significantly enhanced in the cortisol-treated erythrocytes, showing that cortisol had a significant impact on erythrocyte beta-adrenoreceptor dynamics in addition to the direct influence of hypoxia. This study has shown (1) that, by itself, in vitro hypoxia simultaneously initiates the movement of internal receptors to the cell surface, where they become physiologically active, and the replenishment of the internal receptor pool, (2) that cortisol increases receptor availability by increasing the internal pool of low-affinity receptors in the absence of any stimulus for receptor mobilization, and (3) that the sensitivity of erythrocytes to catecholamines is directly proportional to the number of high-affinity receptors present at the erythrocyte surface. Thus, we suggest that, under conditions of chronic stress, cortisol may pre-adapt the erythrocytes to receive additional physiological inputs that can ultimately enhance respiratory performance beyond that which would be possible in the absence of chronically elevated levels of cortisol.

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