Seasonal distribution and habitat selection by the redside shiner, Richardsonius balteatus, in a small Oregon stream

Seasonal habitat availability, utilization, and selection by young of the year (25 mm) redside shiner, Richardsonius balteatus, were studied for 1 year in sections of Greasy Creek, Benton County, Oregon. Intensive stream mapping procedures and snorkling observations provided most of the quantitative measures for habitat availability and utilization respectively. A multivariate discriminant analysis and classification suggested spatial segregation of young of the year and adult redside shiners along gradients of water velocity and depth of the water column. Throughout the year, young redside shiners occupied shallower water than adults and utilized areas with lower mean water velocities. Associated with increased winter stream flows and lowered water temperatures (< 10° C), redside shiners were inactive and found in habitats offering the most cover and refuge from current. Overwintering areas populated by redside shiners included undercut banks, root wads, bank failures, fallen trees, and backwaters. During the transitional period between winter and summer, adult redside shiners shifted from overwintering habitats to the faster water of the main channel. Activities related to spawning and aggressive defense of space accompanied this shift. Young redside shiners continued to utilize protected margins. A multivariate discriminant analysis and classification comparing available and utilized stream habitats provided indices of habitat selection. Both young of the year and adult redside shiners were relatively selective in the stream habitats they utilized. The importance of four physical components (depth, current velocity, substrate composition, and cover forms) varied seasonally and with the life stage considered. Similar patterns of habitat utilization for redside shiners were observed in four larger streams and rivers. The availability of large, deep pools was important, new habitat for both young and adult redside shiners during periods of reduced stream flow in larger streams and rivers

Survey of Parasites In Threatened Stocks of Coho Salmon (Oncorhynchus kisutch) In Oregon By Examination of Wet Tissues and Histology

We are conducting studies on the impacts of parasites on Oregon coastal coho salmon (Oncorhynchus kistuch). An essential first step is documenting the geographic distribution of infections, which may be accomplished by using different methods for parasite detection. Thus, the objectives of the current study were to (1) identify parasite species infecting these stocks of coho salmon and document their prevalence, density, and geographic distribution; (2) assess the pathology of these infections; and (3) for the first time, determine the sensitivity and specificity of histology for detecting parasites compared with examining wet preparations for muscle and gill infections. We examined 576 fry, parr, and smolt coho salmon in total by histology. The muscle and gills of 219 of these fish also were examined by wet preparation. Fish were collected from 10 different locations in 2006–2007. We identified 21 different species of parasites in these fish. Some parasites, such as Nanophyetus salmincola and Myxobolus insidiosus, were common across all fish life stages from most basins. Other parasites, such as Apophallus sp., were more common in underyearling fish than smolts and had a more restricted geographic distribution. Additional parasites commonly observed were as follows: Sanguinicola sp., Trichodina truttae, Epistylis sp., Capriniana piscium, and unidentified metacercariae in gills; Myxobolus sp. in brain; Myxidium salvelini and Chloromyxum majori in kidney; Pseudocapillaria salvelini and adult digenean spp. in the intestine. Only a few parasites, such as the unidentified gill metacercariae, elicted overt pathologic changes. Histology had generally poor sensitivity for detecting parasites; however, it had relatively good specificity. We recommend using both methods for studies or monitoring programs requiring a comprehensive assessment of parasite identification, enumeration, and parasite-related pathology.This is the publisher’s final pdf. The published article is copyrighted by the American Society of Parasitologists and can be found at: http://www.journalofparasitology.org/

Contribution Of Impaired Myocardial Insulin Signaling To Mitochondrial Dysfunction And Oxidative Stress In The Heart

Background—Diabetes-associated cardiac dysfunction is associated with mitochondrial dysfunction and oxidative stress, which may contribute to LV dysfunction. The contribution of altered myocardial insulin action, independently of associated changes in systemic metabolism is incompletely understood. The present study tested the hypothesis that perinatal loss of insulin signaling in the heart impairs mitochondrial function. Methods and Results—In 8-week-old mice with cardiomyocyte deletion of insulin receptors (CIRKO), inotropic reserves were reduced and mitochondria manifested respiratory defects for pyruvate that was associated with proportionate reductions in catalytic subunits of pyruvate dehydrogenase. Progressive age-dependent defects in oxygen consumption and ATP synthesis with the substrates glutamate and the fatty acid derivative palmitoyl carnitine (PC) were observed. Mitochondria were also uncoupled when exposed to PC due in part to increased ROS production and oxidative stress. Although proteomic and genomic approaches revealed a reduction in subsets of genes and proteins related to oxidative phosphorylation, no reduction in maximal activities of mitochondrial electron transport chain complexes were found. However, a disproportionate reduction in TCA cycle and FA oxidation proteins in mitochondria, suggest that defects in FA and pyruvate metabolism and TCA flux may explain the mitochondrial dysfunction observed. Conclusions—Impaired myocardial insulin signaling promotes oxidative stress and mitochondrial uncoupling, which together with reduced TCA and FA oxidative capacity impairs mitochondrial energetics. This study identifies specific contributions of impaired insulin action to mitochondrial dysfunction in the heart

Limited effects of exogenous glucose during severe hypoxia and a lack of hypoxia-stimulated glucose uptake in isolated rainbow trout cardiac muscle

We examined whether exogenous glucose affects contractile performance of electrically paced ventricle strips from rainbow trout under conditions known to alter cardiomyocyte performance, ion regulation and energy demands. Physiological levels of d-glucose did not influence twitch force development for aerobic preparations (1) paced at 0.5 or 1.1 Hz, (2) at 15 or 23°C, (3) receiving adrenergic stimulation or (4) during reoxygenation with or without adrenaline after severe hypoxia. Contractile responses to ryanodine, an inhibitor of Ca(2+) release from the sarcoplasmic reticulum, were also not affected by exogenous glucose. However, glucose did attenuate the fall in twitch force during severe hypoxia. Glucose uptake was assayed in non-contracting ventricle strips using 2-[(3)H] deoxy-d-glucose (2-DG) under aerobic and hypoxic conditions, at different incubation temperatures and with different inhibitors. Based upon a lack of saturation of 2-DG uptake and incomplete inhibition of uptake by cytochalasin B and d-glucose, 2-DG uptake was mediated by a combination of facilitated transport and simple diffusion. Hypoxia stimulated lactate efflux sixfold to sevenfold with glucose present, but did not increase 2-DG uptake or reduce lactate efflux in the presence of cytochalasin B. Increasing temperature (14 to 24°C) also did not increase 2-DG uptake, but decreasing temperature (14 to 4°C) reduced 2-DG uptake by 45%. In conclusion, exogenous glucose improves mechanical performance under hypoxia but not under any of the aerobic conditions applied. The extracellular concentration of glucose and cold temperature appear to determine and limit cardiomyocyte glucose uptake, respectively, and together may help define a metabolic strategy that relies predominantly on intracellular energy stores

A Perspective on Reagent Diversity and Non-covalent Binding of Reactive Carbonyl Species (RCS) and Effector Reagents in Non-enzymatic Glycation (NEG): Mechanistic Considerations and Implications for Future Research

This perspective focuses on illustrating the underappreciated connections between reactive carbonyl species (RCS), initial binding in the nonenzymatic glycation (NEG) process, and nonenzymatic covalent protein modification (here termed NECPM). While glucose is the central species involved in NEG, recent studies indicate that the initially-bound glucose species in the NEG of human hemoglobin (HbA) and human serum albumin (HSA) are non-RCS ring-closed isomers. The ring-opened glucose, an RCS structure that reacts in the NEG process, is most likely generated from previously-bound ring-closed isomers undergoing concerted acid/base reactions while bound to protein. The generation of the glucose RCS can involve concomitantly-bound physiological species (e.g., inorganic phosphate, water, etc.); here termed effector reagents. Extant NEG schemes do not account for these recent findings. In addition, effector reagent reactions with glucose in the serum and erythrocyte cytosol can generate RCS (e.g., glyoxal, glyceraldehyde, etc.). Recent research has shown that these RCS covalently modify proteins in vivo via NECPM mechanisms. A general scheme that reflects both the reagent and mechanistic diversity that can lead to NEG and NECPM is presented here. A perspective that accounts for the relationships between RCS, NEG, and NECPM can facilitate the understanding of site selectivity, may help explain overall glycation rates, and may have implications for the clinical assessment/control of diabetes mellitus. In view of this perspective, concentrations of ribose, fructose, Pi, bicarbonate, counter ions, and the resulting RCS generated within intracellular and extracellular compartments may be of importance and of clinical relevance. Future research is also proposed