Early events in myofibrillogenesis and innervation of skeletal, sound-generating muscle in a teleost fish

The plainfin midshipman, Porichthys notatus, generates acoustic communication signals through the rapid contraction of a pair of vocal (sonic) muscles attached to the walls of the swimbladder. Light and electron microscopic methods were used to study two aspects of sonic muscle ontogeny: 1) the development and transformation of myotubes into muscle fibers and 2) innervation, including the formation of sonic neuromuscular junctions and the myelination of sonic motor axons. Sonic motor axons are associated with sonic mesenchyme during its initial migration away from occipital somites. However, myofibrillogenesis, the formation of neuromuscular junctions, and axon myelination do not occur until sonic mesenchyme reaches its final destination (i.e., the swimbladder). A continuum of developing myotubes is present rather than two temporally distinct populations of primary and secondary myotubes as observed for skeletal muscles in mammalian and avian species. Potential reasons for the lack of primary and secondary myotubes are considered, including the functional homogeneity of the sonic motor system and the sonic muscle's unique architecture, namely its direct attachment to the wall of the swimbladder.     

Levels of histamine and histamine-producing bacteria in smoked fish from New Zealand markets

Smoked fish has been the most commonly implicated product in presumptive cases of scombroid poisoning in New Zealand. One hundred seven samples of smoked fish were purchased from Auckland retail markets between July 1995 and March 1996, and their histamine and bacterial levels were determined. Eight samples, obtained from five of the nine retail outlets sampled, had histamine levels which exceeded 50 mg/kg, the level set by the FDA as an indicator of decomposition. Histamine levels in only 2 samples (346.4 and 681.8 mg/kg) exceeded a hazard level of 200 mg/kg. Thirty-three of the smoked fish were held at 20 degrees C for 2 days, and 8 of these developed histamine levels above 50 mg/kg with 4 exceeding 200 mg/kg (maximum 1,659.4 mg/kg). The stored samples that exceeded 200 mg/kg were all obtained from two outlets. Within or between fish species there were no consistent relationships between levels of histamine in the samples and either the total aerobic plate counts or the numbers of histamine-producing bacteria. To the contrary, there was evidence that histamine had been formed prior to smoking and that histamine-producing bacteria were eliminated during smoking.     

Concentrations and biomagnification of 17 chlordane compounds and other organochlorines in harbour porpoise (Phocoena phocoena) and herring from the southern Baltic Sea

Four species of harbour porpoise (Phocoena phocoena) and one herring (Clupea harengus) sample from the southern Baltic Sea were analysed in an attempt to study the concentration and biomagnification of 17 chlordane related compounds (CHLs) including 12 components present in technical chlordane, the toxic metabolites oxychlordane and cis-hepatchlorepoxide and the photoconversion products photoheptachlor and two photo-cis-chlordanes. The concentration and biomagnification ability of CHLs were also compared to other organochlorines such as HCHs (hexachlorocyclohexanes), hexachlorobenzene, DDTs, dieldrin, mirex and PCBs (polychlorinated biphenyls). Of the CHLs analysed, 16 were detected in porpoise and 15 in herring including the photoconversion products. In both species the highest concentrations were found for PCBs and DDTs. The concentration of PCBs and CHLs in porpoise varied from 5700-16,000 and 470-1250 ng/g lipid, and in herring from 1300 and 49 ng/g lipid, respectively. The biomagnification factor (BMF: concentration in organism/concentration in food; all lipid normalized) in porpoise was found to be high for CHLs followed by dieldrin and lowest for HCHs. Among the CHLs, a big variation of BMF (BMF range approximately 1-50) was found e.g., the nonachlorinated compounds biomagnified to the highest degree followed by cis-heptachlorepoxide, photoheptachlor and oxychlordane.     

Fat, fish, fish oil and cancer

T cell stimulation by triggering through the T cell receptor (TCR) in the absence of costimulatory signals or by calcium ionophore induces unresponsiveness in T cells to further stimulation, a phenomenon known as anergy. In freshly isolated T cells, calcium ionophore induces expression of interleukin (IL)-2 messenger (mRNA), but this mRNA is not translated and not loaded with ribosomes. In addition, while plate-bound anti-CD3 stimulation of resting T cells leads to IL-2 mRNA expression and IL-2 secretion, in cells pretreated with calcium ionophore before anti-CD3 stimulation, the IL-2 mRNA remains polysome unloaded and no IL-2 is produced. These observations show that IL-2 expression is controlled at the translational level, by differential ribosome loading. Furthermore, our data suggest that translational control of IL-2 mRNA may be a molecular mechanism by which anergy is attained.     

Effects of fish meal in beef cattle diets on growth performance, carcass characteristics, and fatty acid composition of longissimus muscle

We investigated the effects of fish meal (FM) in beef cattle diets on growth performance, carcass characteristics, and fatty acid (FA) composition of longissimus muscle in 63 yearling steers (335 +/- 23 kg). High-moisture corn and alfalfa silage diets were supplemented with either a corn gluten/blood meal mixture or FM at 10% of the diet. Fish meal contained (as-is basis) 5.87 g/kg eicosapentaenoic acid (EPA) and 9.84 g/kg docosahexaenoic acid (DHA). Seven strategies were developed to feed either a control diet (no FM) or diets containing 5 or 10% FM with FM fed for either 56, 112, or 168 d before slaughter. Average daily gain and feed efficiency were not affected (P > .10) by FM feeding but DMI decreased. Within FM diets, cattle fed 5% FM consumed more (P < .01) DM and gained more (P < .02) than cattle fed 10% FM. Carcass traits were not affected (P > .05) by feeding strategy except for fatter (P < .05) and lower (P < .06) yielding carcasses in cattle fed 5 vs 10% FM diets. Fish meal feeding increased (P < .01) concentrations of (n-3) FA, including EPA and DHA, and decreased (P < .05) concentrations of arachidonic acid. Increasing the amount of dietary FM further increased (P < .01) concentrations of EPA and DHA and decreased (P < .05) concentrations of (n-6) FA. We estimate that a 114-g steak from cattle fed 10% FM would supply 35 to 90% of the current average daily intake of EPA and DHA in North America. The results indicate that FM may have a role in niche marketing of beef provided that eating quality is not compromised.     

Concentration of mercuro-organic compounds (methyl- and ethyl derivatives) in several species of fish and sea products

By using gas-liquid chromatography the content of organic mercury compounds (methyl- and ethyl derivatives) in some widely consumed in alimentation fish species and marine products was determined. Methyl mercury was found in 96.2 per cent of a total of 104 samples. The average level of its content in the fish species under study was dissimilar, viz. in cod fish--0.045 + .0053 mg/kg. in sea perch--0.021 +/- 0.0029 mg/kg; in sprat--0.0050 +/- 0.0013 mg/kg. In marine products (crustacea, sea crayfish, shrimps) the percentage of the methyl mercury detection comprised 100, 60 and 85, respectively and the contamination level did not exceed 0.0520 mg/kg. Ethyl mercury was found in 33--35 per cent of 40 samples of shrimps and crustacea and in 13.6 per cent of fish subjected to analysis. From the above data the amount of methyl mercury introduced with a diurnal portion of fish was estamated at 0.9--5.0 psi per man-day.     

Aeromonas species in fish, fish-eggs, shrimp and freshwater

Two types of widely coexpressed cell surface C1q-binding proteins (C1q-R): a 60-kDa calreticulin-homolog which binds to the collagen-like "stalk" of C1q and a 33-kDa protein with affinity for the globular "heads" of the molecule, have been described. In this report, we show that the two molecules are also secreted by Raji cells and peripheral blood lymphocytes and can be isolated in soluble form from serum-free culture supernatant by HPLC purification using a Mono-Q column. The two purified soluble proteins had immunochemical and physical characteristics similar to their membrane counterparts in that both bound to intact C1q and to their respective C1q ligands, cC1q and gC1q. In addition, N-terminal amino acid sequence analyses of the soluble cC1q-R and gC1q-R were found to be identical to the reported sequences of the respective membrane-isolated proteins. Ligand blot analyses using biotinylated membrane or soluble cC1q-R and gC1q-R showed that both bind to the denatured and nondenatured A-chain and moderately to the C-chain of C1q. Moreover, like their membrane counterparts, the soluble proteins were found to inhibit serum C1q hemolytic activity. Although cC1q-R was released when both peripheral blood lymphocytes and Raji cells were incubated in phosphate-buffered saline for 1 hr under tissue culture conditions, gC1q-R was releasable only from Raji cells, suggesting that perhaps activation or transformation leading to immortalization is required for gC1q-R release. Subcellular fractionation of Raji cells and analyses by enzyme-linked immunosorbent assay and Western blotting showed that the two molecules are present in the cytosolic fractions as well as on the membrane. The data suggest that soluble forms of both C1q-binding molecules are released from cells and that these molecules may play important roles in vivo as regulators of complement activation.     

Levels of major selenoproteins in T cells decrease during HIV infection and low molecular mass selenium compounds increase

It has been observed previously that plasma selenium and glutathione levels are subnormal in HIV-infected individuals, and plasma glutathione peroxidase activity is decreased. Under these conditions the survival rate of AIDS patients is reduced significantly. In the present study, using 75Se-labeled human Jurkat T cells, we show that the levels of four 75Se-containing proteins are lower in HIV-infected cell populations than in uninfected cells. These major selenoproteins migrated as 57-, 26-, 21-, and 15-kDa species on SDS/PAGE gels. In our earlier studies, the 57-kDa protein was purified from T cells and identified as a subunit of thioredoxin reductase. The 26- and 21-kDa proteins were identified in immunoblot assays as the glutathione peroxidase (cGPX or GPX1) subunit and phospholipid hydroperoxide glutathione peroxidase (PHGPX or GPX4), respectively. We recently purified the 15-kDa protein and characterized it as a selenoprotein of unknown function. In contrast to selenoproteins, low molecular mass [75Se]compounds accumulated during HIV infection and migrated as a diffuse band near the front of SDS/PAGE gels.     

An electron microscopic investigation into the possible source of new muscle fibres in teleost fish

This study is based on transmission electron microscopic (TEM) investigations of deep (fast, 'white') teleost fish muscle proliferation in early developmental stages of three European cyprinid species and the rainbow trout. Our fine structural findings provide evidence that early myotomal growth in these animals may utilize different mechanisms that are activated in close succession during early life history. First, initial enlargement of the deep muscle bulk in the embryo seems to be due to hypertrophy of the somite-cell derived stock of muscle fibres. Second, we suggest that deep muscle growth becomes additionally powered by attachment of presumptive myogenic cells that originate from and proliferate within the adjacent mesenchymal tissue lining. Third, mesenchyme-derived muscle cell precursors are thought to enter the myotomes via the myosepta. After migration between the pre-established muscle fibres these cells may function as myosatellite cells, thus at least partly providing the stem cell population for subsequent rapid hyperplastic growth. Finally, there is evidence that presumptive deep muscle satellite cells also proliferate by mitotic division in situ. A similar process of myogenic cell migration and proliferation may foster intermediate fibre differentiation. The model of myogenic cell migration is discussed in view of in vitro and in vivo data on satellite cell migratory power and with respect to temperature-induced and species dependent differences. As for the latter, our results indicate that patterns of muscle differentiation may diverge between a fast growing salmonid species and a moderately growing cyprinid species of similar final size. The model is compatible with the well-established idea that teleost muscle growth may rely on different subclasses of myosatellite cells.     

Fish, fish oils, arrhythmias and sudden death

Cardiovascular morbidity and mortality is relatively low in individuals with a high consumption of fish oils containing omega-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid). This has been mainly attributed to the anti atherogenic and anti thrombotic effects of these oils. However, recent evidence suggests that fish and fish oils may also prevent malignant ventricular arrhythmias and sudden cardiac death. Several animal experiments have shown that fish oils can reduce the incidence of ischaemia induced ventricular tachycardia and fibrillation. Observational studies in humans have shown that there is a connection between the intake of omega-3 fatty acids and a lower risk of sudden cardiac death. Some trials suggest that fish oils can prevent ventricular arrhythmias in humans. It is possible that the effect of fish oils on arrhythmias is independent of their anti atherogenic and anti thrombotic activities. There is also some evidence that these oils affect ion fluxes in cardiomyocytes.     

Levels of processing, encoding specificity, elaboration, and CHARM.

[Correction Notice: An erratum for this article was reported in Vol 92(4) of Psychological Review (see record 2008-10981-001). Equation 5 on page 11 was incorrect. The correct equation is given in the erratum.] A model of cued recall called CHARM (composite holographic associative recall model) is applied to several issues that have been investigated within the depth-of-processing framework. It is shown that, given some straightforward, empirically testable assumptions about the representations of the to-be-remembered items themselves, CHARM can account for the main effect of depth of processing, the problem of the negatives, encoding–specificity interactions, and both facilitative and inhibitory effects of elaboration. The CHARM model is extended to encompass some depth-of-processing effects found in recognition memory. The highly interactive associative, storage, and retrieval mechanisms in the CHARM model are discussed. (90 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Plutonium in fish, algae, and sediments in the Barents, Petshora and Kara Seas

This work contributed to a joint research programme between the Finnish Centre for Radiation and Nuclear Safety and the Murmansk Marine Biological Institute in the Arctic. Radioanalyses for plutonium isotopes were performed on more than 50 sediment samples, 12 algae samples and 19 fish samples. Plutonium concentrations in algae and fish samples, including fish meat, bone and liver, were low or in many cases below detection limits. Some differences in plutonium concentrations of sediments were found between different sampling areas. However, the concentrations were low. The Pu isotopic ratios were similar to those found in environmental samples generally when Pu is derived from global fallout or discharges from reprocessing plants. No local enhancement of plutonium contamination was found in the marine areas studied. However, the sampling locations represent only areas of free access; prohibited military areas of North-west Russia with potential pollution sources were not included.     

Self-Monitoring, Activity Levels, and Mood in the Development and Maintenance of Depression.

The reactive effect on mood of self-monitoring pleasant and unpleasant events was assessed. Forty-five females spent 28 days monitoring in one of four conditions: (a) pleasant events, (b) unpleasant events, (c) both, and (d) no monitoring. Motor activity level (pedometer recordings) and mood were also assessed daily. Class of event monitored was not found to influence mood. Correlations between mood and both pleasant and unpleasant events were found even with activity level partialed out. Implications for self-monitoring assessment in depression therapy programs and for models of depression are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sleep in a schooling fish, Tilapia mossambica

A test that circumvents the complex methodology needed for the determination of L/S ratios has been developed. It has been observed that the optical density, measured at 400 nm, of supernatants collected from fresh amniotic fluids centrifuged at 2000 g for 10 minutes correlates with L/S ratios.     

Species and organ dependence of PCB contamination in fish, foxes, roe deer, and humans

According to previous experimental results, PCBs are deposited in muscle fat in animals and in humans, although they also reach the brain, the liver, and the lungs. The aim of the present study was to determine the concentrations of the so-called "indicator PCBs" (PCB nos. 28, 52, 101, 138, 153, 180), as described by the German ordinance for maximum concentrations of contaminants in foodstuffs, in muscle tissue, liver, and brain of four different species: fish, fox, roe deer, and humans, all exposed to PCBs directly in their environment. Potential target organs for the accumulation of these congeners were also to be identified. Furthermore, the organs or tissues were to be identified in which PCBs are accumulated, and unusual patterns of accumulation or breakdown of particular PCBs, for example the "dioxin-like PCBs" (coplanar PCBs) determined. For humans, the lungs were also included in these studies. Statistical comparison of PCB concentrations in samples from wild animals and humans showed that in spite of its relatively high fat concentration, brain tissue in all of the species examined (with the exception of fish) appeared to be better protected against accumulation of PCB than liver or muscle tissue. This protection may be the result of the blood-brain barrier, as witnessed by the relatively uniform concentration of PCBs throughout the various organs of fish, since the blood-brain barrier of fish is considerably less efficient than that of mammals. No peculiarities were found in regard to distribution of the coplanar PCBs over the other congeners in this study. This applies to the brain and other organs or tissues of the four species that were examined. Accumulations of PCBs and coplanar PCBs in the liver were only found in fox and roe deer. In contrast, humans were found to have accumulations of the high-chlorinated biphenyls studied here as well as PCB no. 118 in muscle tissue fat and not in the liver. Unexpectedly, low-chlorinated biphenyls were found to accumulate in the human lung. The results of this study show that the lung represents a target organ for the accumulation of potentially metabolically activated low-chlorinated biphenyls, indicating that the possible biological effects of PCBs on the lungs will need to receive more attention in the future.     

Morphology, fine structure, biochemistry, and function of the spermatic ducts in marine fish

The spermatic ducts and the testicular efferent ducts were investigated in different marine teleost fish species (Diplodus sargus, Mullus barbatus, Thalassoma pavo, Trachinus draco, Uranuscopus scaber, Sparisoma cretense, Synodon saurus). From the morphological, histological, fine structural and biochemical investigations it appeared that the testicular main ducts and spermatic ducts of the investigated marine fish have the following functions: storage of spermatozoa, monosacharide synthesis for nutrition of spermatozoa, synthesis of steroid glucuronides, synthesis of seminal plasma proteins, formation of a ionic gradient in the seminal fluid and phagocytotic activity. Species-specific differences were only found in the morphology of the gonads and in the histology of the spermatic duct epithelium.