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The present study was conducted to elucidate the effects of copper exposure on the immune system and lipid metabolism of the Japanese scallop, Mizuhopecten yessoensis . Transcriptional levels of differentially expressed genes (DEGs)in M. yessoensis digestive gland tissue were analyzed using the deep-sequencing platform Illumina HiSeq™ 2000. In total, 841 and 877 genes were identified as significantly up- or down-regulated, respectively. In addition, significant enrichment analysis identified 3 gene ontology terms and 15 pathways involved in the response to copper exposure. Analysis of transcripts related to the immune response revealed a complex pattern of innate recognition receptors, including toll-like receptors, NOD-like receptors and downstream pathway effectors, including those involved in apoptosis. Furthermore, genomic analysis revealed that genes involved in extracellular matrix (ECM)-receptor interactions were enriched in Cu-exposed scallop glands. These results will provide a resource for subsequent gene expression studies regarding heavy metal exposure and the identification of copper-sensitive biomarkers for the aquaculture of M. yessoensis . [ABSTRACT FROM AUTHOR]

Modern feeds for industrial salmon farming are presently formulated to fulfill specific digestible protein (DP, grams per kg feed, hereafter called units) and digestible energy (DE, Mega Joule (MJ) per kg feed) specifications. In the present study, 299 feed samples and accompanying fecal samples were obtained from 43 different farming sites for Atlantic salmon along the coast of Norway between October 2010 and February 2013. Apparent digestibility coefficients for protein and fat were calculated from protein and fat in feed and fecal matter, using analyzed crude fiber contents as a digestibility marker. Overall mean apparent protein and fat digestibilities were 87.1% (±4.9; overall mean±S.D.) and 92.5% (±3.7), respectively. Linear mixed models with rearing site as random effect were applied to evaluate factors that influenced the apparent digestibility of protein and fat, feeding intensity and energy intake. Apparent digestibility of fat tended to increase over the study period, and both feed type and feed manufacturing company, and water temperature influenced the digestibility significantly. Digestible energy content (DE, MJ/kg) was significantly negatively associated with feeding intensity, but not with total digestible energy intake. Variation at site level was significant in all analyses, and was moderate for the digestibility analyses and high regarding feeding intensity and energy intake. Digestibility assessments were used to assess accuracy, precision and agreement between optimized and realized digestible protein (DP, %) and DE level of feeds, using the mean difference between the two sets of observations and a fixed contribution of dietary energy from starch. Overall mean difference between realized and optimized DP and DE was −0.28units and −0.56MJ/kg, respectively, and there were significant differences between feed manufacturing companies. The results indicated that field digestibility assessments can be used to validate nutritional and economical value of feeds in commercial salmon farming. [ABSTRACT FROM AUTHOR]

Studies aimed to assess the digestive physiology of marine fish larvae under culture conditions are important to further understand the functional characteristics and digestive capacities of the developing larvae. Most studies to date concentrate on intestinal lumen digestion and little attention to the absorption process. Thus, the objectives of this study were to histochemically detect and quantify some of the enzymes responsible for absorption and intracellular digestion of nutrients in the anterior and posterior intestine of California halibut larvae. Alkaline and acid phosphatases were detected from the first days post-hatch (dph). Alkaline phosphatase maintained a high level of activity during the first 20 dph in both intestinal regions. Thereafter, a clear intestinal regionalization of the activity was observed with the highest levels occurring in the anterior intestine. Acid phosphatase activity gradually increased in both intestinal regions during development, and a regionalization of the activity was not observed until late in development, once the ocular migration began. Highest levels were observed in the anterior intestine at the end of metamorphosis concomitant with the stomach development. The results from this study show some morphological and physiological changes are occurring during larval development and a clear regionalization of the absorption process as the larvae develops. These ontological changes must be considered in the elaboration of diets according to the digestive capacity of the larvae. [ABSTRACT FROM AUTHOR]