Branchial nitrogen cycle symbionts can remove ammonia in fish gills.

Knowledge of the mechanisms by which fish excrete their metabolic nitrogenous waste and insights into nitrogen cycling in aquaculture systems is of utmost importance to improve the sustainable commercial production of fish. In fish, most nitrogenous waste is excreted via the gills as ammonia, a potentially toxic nitrogenous compound. In this study; activity assays, physiological experiments, molecular analysis and microscopy were used to show that the gills of fish harbor a unique combination of hitherto overlooked nitrogen-cycle microorganisms that can theoretically detoxify excreted ammonia by converting it into inert dinitrogen gas.

Differential host utilisation by different life history stages of the fish ectoparasite Argulus foliaceus (Crustacea: Branchiura).

In this study we examine differences in the occurrence of life history stages of the destructive fish ectoparasite Argulus foliaceus (L., 1758) on eight fish species (stickleback, rudd, roach, gudgeon, bream, tench, crucian carp and common carp) sampled from a mixed-species recreational fishing lake on nine occasions during late spring and summer. Total numbers ofA.

Transcriptional analysis of the common carp (Cyprinus carpio L.) immune response to the fish louse Argulus japonicus Thiele (Crustacea: Branchiura).

In the present study we investigated changes in transcription levels of a panel of selected immune relevant genes in peripheral blood leucocytes (PBL) and skin samples collected from carp exposed to larval Argulus japonicus. We show that in skin up-regulation of gene transcription of the chemokine CXCa, and to a lesser extent the chemokine receptor CXCR1 and the cytokine TNFalpha, are good indicators of parasite-induced skin damage at 2 days post-parasite exposure. Up-regulation of gene transcription corresponded well with an increase in leucocytes, probably neutrophilic granulocyte numbers in skin samples collected at the sites of infection.

Metabolic and thyroidal response in air-breathing perch (Anabas testudineus) to water-borne kerosene.

To address the physiological compensatory adaptations in air-breathing fish to a toxicant, we studied the metabolite pattern, serum and liver enzymes and thyroidal response in a tropical air-breathing perch, Anabas testudineus (kept at 30 degrees C in a 12-h L:D cycle) after exposing the fish for 48h to the water-soluble fraction of kerosene. The concentrations of serum glucose (P <0.05), triglycerides (P <0.

Opercular epithelial cells: a simple approach for in vitro studies of cellular responses in fish.

This study evaluated the efficacy of fish opercular external (skin) and inner (opercular membrane) epithelium as an in vitro model for toxic and other substances studies. The rainbow trout (Oncorhynchus mykiss) operculum was cultured in 12-well dishes containing sterile Leibovitz 15 (L-15) supplemented with glutamine medium during 24h at 9 degrees C, and the effect of copper, a toxic agent, and/or cortisol, an endogenous agent, on the epithelial cells was analyzed using light microscopy techniques. The opercula were submitted to four treatments: (i) control (Cont), L-15 medium only, (ii) 0.

Localization, expression and control of adrenocorticotropic hormone in the nucleus preopticus and pituitary gland of common carp (Cyprinus carpio L.).

Adrenocorticotropic hormone (ACTH) takes a central role in the hypothalamo-pituitary-interrenal axis (HPI axis), which is activated during stress. ACTH is produced by the corticotrope cells of the pituitary pars distalis (PD) and is under control of factors from the nucleus preopticus (NPO). The distribution of ACTH in the hypothalamo-pituitary system in common carp (Cyprinus carpio L.

Environment affects stress in exercised turbot.

We investigated the interaction of water temperature (10, 18 and 22 degrees C) and salinity (33.5 and 15 per thousand ) on the stress response of juvenile turbot. At each temperature/salinity combination, fish were subjected to 10 min enforced exercise.

Effects of acetylsalicylic acid treatment on thyroid hormones, prolactins, and the stress response of tilapia (Oreochromis mossambicus).

The cyclooxygenase (COX) pathway converts arachidonic acid (ArA) into prostaglandins (PGs), which interact with the stress response in mammals and possibly in fish as well. Acetylsalicylic acid (ASA) is a COX inhibitor and was used to characterize the effects of PGs on the release of several hormones and the stress response of tilapia (Oreochromis mossambicus). Plasma PGE2 was significantly reduced at 100 mg ASA/kg body wt, and both basal PGE2 and cortisol levels correlated negatively with plasma salicylate.

Regulation of branchial Na(+)/K(+)-ATPase in common carp Cyprinus carpio L. acclimated to different temperatures.

Isogenic carp Cyprinus carpio L. were acclimated to water temperatures of 15, 22 and 29 degrees C for at least 8 weeks. The acclimations consistently resulted in slightly, but significantly, different plasma osmolality, sodium, potassium and chloride concentrations between the groups studied.

Temperature-induced changes in thyrotropin-releasing hormone sensitivity in carp melanotropes.

This study investigates whether thyrotropin-releasing hormone (TRH), alpha-melanocyte-stimulating hormone (alpha-MSH) and N-acetyl beta-endorphin (NAc beta-END), or the thyroid hormones thyroxine (T4) and 3,5,3'-triiodothyronine (T3) are involved in the physiological response to temperature changes in the poikilotherm common carp (CYPRINUS CARPIO). Carps were either subjected to a rapid cold exposure or acclimated over time to three different temperatures. Acute cold exposure did not influence blood plasma alpha-MSH concentrations.

Distribution and quantification of corticotropin-releasing hormone (CRH) in the brain of the teleost fish Oreochromis mossambicus (tilapia).

The recent characterization of the corticotropin-releasing hormone (CRH) prehormone of the fish tilapia (Oreochromis mossambicus) showed that more variation exists between vertebrate CRH amino acid sequences than recognized before. The present study investigates whether the deviating composition of tilapia CRH coincides with an atypical distribution of CRH in the brain. For this purpose we applied immunohistochemistry, as well as radioimmunoassay (RIA) quantification in brain slices.

Stress response to waterborne Cu during early life stages of carp, Cyprinus carpio.

Following in vitro fertilization, eggs/embryos and larvae of the common carp (Cyprinus carpio) were exposed to 0 (control), 0.3 or 0.8 micromol.