Two feeding experiments were conducted to determine the suitable dietary protein and lipid levels for fingerlings of red sea bream by feeding them with various white fish meal-casein diets containing different levels of protein (CP: 37-52%) and lipid (CL: 5-20%).In Experiment I, the growth rate and feed efficiency increased with increasing CP content in diet, both values reaching a maximum at the diet level of 52%. In Experiment II, the growth rate and feed efficiency were higher for diets containing 52% CP, compared to 42% CP groups, irrespective of the lipid levels. On the other hand, with an increase in the amount of dietary n-3HUFA, the values for growth rate, feed efficiency, and protein efficiency ratio increased, recording high in diets combining 52% CP with 15 and 20% lipids.This result indicated that the growth of red sea bream fingerlings was influenced by not only dietary protein and lipid levels but also n-3HUFA contents in diet. It is also suggested that the suitable CP and CL levels in diet for red sea bream fingerlings may be around 52% and 15%, respectively.

SUMMARY: Otolith increments of bluefin tuna Thunnus thynnus were examined to estimate the periodicity of an increment formation and the timing of the first increment formation using larvae and juveniles with known age reared in three laboratories. The increment was formed daily up to 71 days after fertilization. The first increment was formed on the fifth day after fertilization, and around the fourth day after hatching which corresponded to the onset of feeding. Slower growing fish had otoliths with less distinct increments. Since wild captured larvae had otoliths with more distinct increments, fish in the wild either grow faster than that in a laboratory or only faster grown fish survived in the wild.

This experiment was conducted to confirm the relationship between dietary lipid levels and n-3 highly unsaturated fatty acids (n-3HUFA) contents and to determine a suitable n-3HUFA content in diet for fingerlings of red sea bream by feeding them with various white fish meal-casein diets containing different amounts of lipid (5-20%) and n-3HUFA (1.2-4.2%) at a fixed protein level of 52%.At a level of 10% lipid, growth was lowered as n-3HUFA content in the diet increased, and the lowest feed performances were obtained in fish fed on a diet containing 3.7% n-3HUFA. On the other hand, at 15% lipid, the growth and feed efficiency were not affected by elevation of dietary n-3HUFA content, reaching a maximum at 3.7% n-3HUFA. Furthermore, at a level of 20% lipid, growth rate and feed efficiency were also improved as the n-3HUFA content increased, recording high in diets containing n-3HUFA above 3.7%. These results clearly indicated that the n-3HUFA content in diet should be increased in proportion to dietary lipid levels to obtain maximum growth. Moreover, the best growth and feed efficiency were obtained in fish fed on a diet with 15% lipid when n-3HUFA was adjusted to the level mentioned above.Thus, the growth of red sea bream fingerlings was found to be greatly influenced by dietary n-3HUFA levels, a suitable level being approximately 20% in dietary lipid regardless of lipid levels.

BackgroundDiet-induced hepatic steatosis is highly associated with nonalcoholic fatty liver disease, which is related to the development of metabolic syndrome. While advanced stage nonalcoholic hepatic steatosis and steatohepatitis (NASH) result ultimately in fibrosis and cirrhosis, the molecular basis for lipid droplet formation is poorly understood. Common pathways underlie the pathology of mammalian obesity and the zebrafish diet-induced obesity model (DIO-zebrafish) used in this study.MethodsOur analysis involved a combination of transcriptome (DNA microarray) and proteome (two-dimensional electrophoresis) methods using liver tissue from DIO-zebrafish to find candidate genes involved in hepatic steatosis. We conducted intraperitoneal injection (i.p.) of morpholino antisense oligonucleotides (MOs) for each gene into DIO-zebrafish. We also conducted in vitro overexpression in human cells. Additionally, we examined gene expression during feeding experiments involving anti-obesity compounds, creatine and anserine.ResultsWe found that fatty acid binding protein 3 (fabp3) and E2F transcription factors were upregulated in hepatic steatosis. E2f8 MO i.p. suppressed fabp3 expression in liver, and ameliorated hepatic steatosis. In human cells (HepG2), E2F8 overexpression promoted FABP3 expression. Additionally, co-administration of creatine and anserine suppressed obesity associated phenotypes including hepatic steatosis as indicated by e2f8 and fabp3 down regulation.ConclusionWe discovered that the e2f8–fabp3 axis is important in the promotion of hepatic steatosis in DIO-zebrafish. The combination of transcriptome and proteome analyses using the disease model zebrafish allow identification of novel pathways involved in human diseases.Electronic supplementary materialThe online version of this article (doi:10.1186/s12986-015-0012-7) contains supplementary material, which is available to authorized users.

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