In primary cell preparations from larvae of rainbow trout Oncorhynchus mykiss, the formation of autonomously contracting cell aggregates was observed after 7 days. These contracting elements could be propagated and some aggregates were maintained over a period of 35 days. Electron microscopical and immunocytochemical examination revealed the presence of cardiomyocytes.
Peptidylarginine deiminase (PADI)-like cDNA sequence was isolated from rainbow trout (Oncorhynchus mykiss). It consists of a 111-bp 5'-untranslated region, a 731-bp 3'-UTR, and a 2,010-bp open reading frame encoding a protein of 669 amino acids. In the presence of calcium ions, PADI enzymes catalyze the post-translational modification reaction generating citrulline residues. Mammalian PADI enzymes are involved in a number of regulatory processes during cell differentiation and development such as skin keratinization, myelin maturation, and histone deimination. Though five PADI isotypes have been isolated from mammals, in bony fish only one PADI enzyme is present, which contains conserved amino acid residues responsible for catalysis and calcium ion-binding. Sequence identity of piscine PADI protein sequences available at gene databases exceeds 67%. Phylogenetic analyses revealed that not only piscine, but also amphibian and avian PADI-like proteins share most identical amino acid residues with mammalian PADI2. mRNA level of trout PADI-like gene is high in skin, fin, gills, brain, and spleen of rainbow trout. Quantitative Real-Time RT-PCR revealed that PADI gene is differentially expressed in liver, trunk kidney, and spleen of two trout strains, the freshwater-cultured STEELHEAD trout and the brackish water strain BORN.
The Ca(2+)-binding protein regucalcin (RGN) is crucial for the regulation of Ca(2+) ion homeostasis and signal transduction of cells. It is involved in the regulation of Ca(2+)-dependent protein kinases and Ca(2+) pump enzymes in cell membranes. Comparative transcriptome analysis in healthy fish of two aquacultured rainbow trout (Oncorhynchus mykiss) lines (BORN, TCO) varying in susceptibility to environmental stress identified significant differences in the expression of the RGN gene. Therefore, we firstly determined the full genomic DNA and cDNA sequence of RGN gene from rainbow trout and comparatively investigated the complete cDNA sequence in another salmonid fish dedicated for local aquaculture, the maraena whitefish (Coregonus marena). The sequence coding region translates for proteins of 298 and 299 amino acids (aa), respectively, indicating a high conservation of RGN proteins (95.7% aa identity) between the two related salmonids. In the second place, we generated RGN gene expression profiles after pathogen (Aeromonas salmonicidae subsp. salmonicida) and temperature (8 and 23°C) challenge in the two rainbow trout lines using salmon microarrays and quantitative RT-PCR. The profiles not only verified initially detected gene expression differences, they also display a tissue specific gene expression in dependence from the stressor and time. The differences in gene expression support our assumption that RGN might play a role in recovery of rainbow trout after environmental stress.
In order to facilitate intercontinental air transport of live sturgeon broodstock, a simulation test for an 8-h flight was performed in a pressure chamber (pressure profiles resembling conditions during trans-Atlantic cargo flights). Atlantic sturgeon (Acipenser oxyrinchus) were maintained in sealed polyethylene bags with water and an oxygen-enriched atmosphere at a ratio of 1 : 5 : 10 (fish:water:oxygen by volume) over a 10 h period at 15°C water temperature. Minimum pressure during the simulated flight was regulated at an elevation of 2600 m equalling 850 hPa. Decompression and compression phases to simulate takeoff and landing were set at 30 min each. Respiration frequency was recorded during flight simulation. Blood pH, blood pO 2 and pCO 2 as well as Ca 2+ , Na + , K + , Cl ) , glucose and cortisol, cholesterol and trigycerids were also monitored prior to and after transport (at 12, 24, 36, 280 and 366 h). During exposure in the bags, blood pH decreased from a mean of 7.35 to 7.11 and blood pCO 2 increased from 2.48 to 8.53 hPa. Both parameters revealed the most significant deviations from control levels immediately following the trial, returning to normal levels after 36 h. In contrast, the Na 2+ , Ca 2+ and Cl ) ion as well as glucose concentration required 72 h following the simulated transport until baseline levels were reached. During the subsequent transatlantic transport trials from Canada to Germany, blood parameters were utilized to assess fish recovery following transport. Additionally, testing of the transport water revealed that NH 4 -N reached critical levels of 6 mg l )1 within 16-18 h when the fish were kept in the sealed bags at 10°C. Following transport, adaptation of pH in the water of the rearing facility to levels of pH 6.9-7.0 for 20-28 h minimized toxic NH 3 concentrations and ensured recovery. Recovery times varied to a large extent, influenced by the condition factor of the fish. Fish survival was 100% for 2 months post-transport, indicating that the critical parameters were met during transport.
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