Structural changes in the erythrocyte membrane of the trout Salmo irideus at seasonal acclimatization

Differences of thermostability were studied in red blood cells of the trout Salmo irideus differing in sex and age, as well as structural-dynamic characteristics of erythrocyte membrane proteins at seasonal acclimatization in the interval of reservoir water temperature of 0–19°C. An increase of resistance of erythrocytes to temperature lysis with elevation of the environmental temperature was revealed to be accompanied by a rise of the proteins segmental mobility and a decrease of intermolecular interactions in spectrin-actin cytoskeleton from the data of the ESR spin labeling method. Regulation of erythrocyte stability during acclimation was concluded to occur both changes of the fatty acids chain package at the variations of lipid composition and by changes of the cytoskeleton structural lability. Thereby this provides an increase of the bilayer firmness, on the one hand, while, on the other hand, a rise of elasticity and expansibility of the membrane on the whole, which increases resistance of cells to colloidal-osmotic hemolysis. Changes of concentration of oxygen dissolved in water, which are caused by temperature fluctuations, do not deem to be of crucial importance for structural stability of erythrocytes, as it can be compensated by another mechanism, specifically by changes of affinity of hemoglobin to oxygen.     

Amino acid sequence of alpha-chain of hemoglobin IV from trout (Salmo irideus)

The amino acid sequence of the alpha-chain of trout hemoglobin (Hb) IV is given, thus completing the primary structure of the hemoglobin component of trout's blood characterized by the Root effect. The trout Hb IV alpha-chain consists of 142 amino acid residues; comparison with the corresponding sequences from human and carp hemoglobins shows differences of 50.0 and 35.9%, respectively. A difference of 39.6% is found with the alpha-chain of trout Hb I, the other major hemoglobin component of trout blood, devoid of heterotropic effects.     

Effects of siltation on resource utilization and dynamics of allopatric brown trout,Salmo trulta,in a reservoir

Synopsis The water level of the old hydroelectric Ringedal Reservoir in western Norway was unusually low during 1985, resulting in severe erosion and siltation. The secchi disc transparency was 18 m in July 1984, decreased to 0.3 m in July 1985, and increased to 13 m in July 1986 after a rise in the water level. The abiotic changes induced major effects in the zooplankton community, with a strong reduction in occurrence of Cladocera (Holopedium gibberum andBosmina longispina). The allopatric population of brown trout,Salmo trutta, which mainly fed on zooplankton before the siltation, fed predominantly on surface insects during the summer of high siltation. The food consumption was lower than in the pre- and post-siltation years, resulting in reduced k-values, reduced number of spawners, and increased mortality of mature fish.     

Effect of anions on the oxygen binding properties of the hemoglobin components from trout (Salmo irideus).

The effect of several anions on the oxygen equilibrium of hemoglobin components (Hb Trout I, II, and IV) from trout has been investigated.The functional properties of Hb Trout I and II are very slightly affected by organic phosphates (ATP, IHP) and pyridoxal phosphate. On the other hand the oxygen affinity of both components is affected, to the same extent, by the presence of sodium chloride; this effect seems to be pH and temperature independent. For Hb Trout I experiments on the effect of orthophosphate, pyrophosphate and pyridoxal phosphate point to a certain degree of correlation between the size of the phosphate and its effect on the functional behavior of the protein.In the case of Hb Trout I and II the differences in the effect of the various organic and inorganic phosphates may be interpreted, at a molecular level, in terms of loss of charge complementarity and (or) steric hindrance effects.On the other hand, as in the case of human hemoglobin, organic or inorganic phosphates decrease the oxygen affinity of Hb Trout IV. In addition various phosphates shift the region where the Root effect is operative toward higher pH values, thereby acting as allosteric effectors. For pyridoxal phosphate, kinetic experiments have shown that the rate of binding to Hb trout IV is several orders of magnitude smaller than that for other organic phosphates, similarly to what has been reported for human hemoglobin.     

The population dynamics of young trout (Salmo trutta L.) in a Danish brook

The population size, dispersal of fry, growth of fry in relation to density, mortality and production of young trout ( Salmo trutta L.) were studied in a Danish brook during 1970–1972. In the first few months after emergence downstream emigration of fry took place both in 1971 and 1972, after which the trout became stationary. Growth was inversely density dependent and mortality was density dependent in the months just after emergence. Later mortality was constant and independent of density. Trout production varied between 10 g/m² and 18.6 g/m² in the 2 years.     

Synchrony in brown trout, Salmo trutta, population dynamics: a 'Moran effect' on early-life stages

Synchrony among populations (i.e. spatial covariation in temporal fluctuations of population size or growth rate) is a common feature to many animals. Both large-scale autocorrelated climatic factors (the 'Moran effect') and dispersal between populations are candidates to explain synchrony, although their relative influence is difficult to assess. Only a few investigations have reported patterns of synchrony among freshwater populations, and even fewer directly related these patterns to an environmental variable. In the present study, we analysed the spatio-temporal patterns of fluctuation of 57 brown trout populations widespread across France, each sampled continuously during 5 years. We compared the respective influence of connectivity and stream distance within basins (i.e. that potentially allow a basin-scale dispersal) and environmental factors (hydrological and air temperature variables, available for 37 sites) on the synchrony of brown trout cohort densities (0+, 1+ and adults). A series of Mantel tests revealed that the degree of synchrony was not related to connectivity or stream distance between sites, suggesting no effect of dispersal at the basin-scale. The degree of synchrony among sites for the 0+ fish was significantly related to the degree of hydrological synchrony (based on high flows during the emergence period). For all three age classes, the synchrony in the temperature patterns did not explain synchrony in trout dynamics. Our results allow us to discuss the respective influence of dispersal and climatic factors on the spatio-temporal patterns of trout dynamics at the basin scale.