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Keywords: arachidonic acid; characterization; cloning; Cynoglossus semilaevis; pmch2; sex dimorphism EN arachidonic acid characterization cloning Cynoglossus semilaevis pmch2 sex dimorphism 3472 3477 6 07/14/20 20200801 NES 200801 Melanin-concentrating hormone (MCH), originally discovered in the teleost pituitary, is a hypothalamic neuropeptide involved in the regulation of body colour in fish (Cerdá-Reverter & Canosa, 2009; Kawauchi, Kawazoe, Tsubokawa, Kishida, & Baker, 1983; Mizusawa, Kasagi, & Takahashi, 2018; Mizusawa, Kobayashi, Yamanome, Saito, & Takahashi, 2013; Mizusawa, Yamamura, Kasagi, Cerdá-Reverter, & Takahashi, 2018). The deduced Chinese tongue sole pMCH2 contains a 24-amino acid signal peptide (MISVSSVLITLVLSSVLSSHLVVVA) and a dibasic (RR) cleavage site near the C terminus that likely is used to generate the MCH peptides, a 23-amino acid peptide (NTELDMLRCMIGRVYRCWGTSN). The functions of MCH in fish reproduction and a potential gender difference in MCH action would merit investigation. Arachidonic acid, characterization, cloning, Cynoglossus semilaevis, pmch2, sex dimorphism. [Extracted from the article]

Abstract: The lipid‐regulating effects of astaxanthin (ASTX) have been widely reported in terrestrial animals. However, little relevant information has been available in fish although ASTX has been used as exogenous pigment and antioxidant in fish feed. A 74‐day feeding study was conducted to investigate the effects of dietary ASTX on lipid accumulation in the marine teleost tiger puffer. Four experimental diets differing only in ASTX supplementation, that is, 0 (control), 50 (ASTX50), 100 (ASTX100) and 500 (ASTX500) mg kg‐1, were randomly assigned to 12 tanks of juvenile tiger puffer. Compared to control, the liver lipid content in group ASTX50 was significantly higher, while those in groups ASTX100 and ASTX500 were lower. The muscle lipid contents in group ASTX500 were significantly higher compared to control. Group ASTX50 had the best growth performances, while diet ASTX500 seemed to have adverse effects. In the liver, compared to control, groups ASTX50 and ASTX100 showed significantly lower mRNA expressions of genes related to triglycerol synthesis and fatty acid synthesis, transport and uptake, but higher expressions of genes related to β‐oxidation and monoglycerol hydrolysis. In the muscle, compared to control, ASTX100 showed higher expressions of genes related to β‐oxidation. ASTX50 resulted in higher contents of saturated and monounsaturated fatty acids but lower contents of n‐3 polyunsaturated fatty acids in fish. In conclusion, astaxanthin in diets for tiger puffer differentially regulated the lipid accumulation in the liver and muscle, both in dose‐dependent manners. Excess dietary astaxanthin (500 mg/kg) had adverse effects on tiger puffer. [ABSTRACT FROM AUTHOR]

In this study, putative cDNA of three fatty acid transport protein ( FATP) isoforms, that is FATP1, FATP4 and FATP6, was cloned and characterized from the liver of Japanese seabass ( Lateolabrax japonicus), and their expression in response to diets with different arachidonic acid ( ARA) levels (0.05%, 0.22%, 0.37%, 0.60%, 1.38% and 2.32% of dry matter) was investigated through a feeding trial. Two subtypes of FATP1, that is FATP1a and FATP1b, were cloned for the first time. The Japanese seabass FATPs showed high identity to their orthologs in other fish species and mammals, but Japanese seabass FATP6 showed low identity to Japanese seabass FATP1 and FATP4. FATP1a gene was highly expressed in brain, liver and eye, whereas FATP1b had the highest gene expression in gill, followed by kidney, skin, eye, muscle and heart. FATP4 gene was primarily expressed in intestine, brain and eye. However, FATP6 had very low gene expression levels in almost all tissues. High levels of dietary ARA (0.60%~2.32%) enhanced the gene expressions of FATP1a and FATP4 in the intestine and the gene expression of FATP1a in the muscle, whereas the dietary ARA supplementation reduced the FATP1b mRNA expression in the liver. The gene expression of FATP1a, FATP4 and FATP6 in the liver, as well as the FATP4 gene expression in the muscle, was not significantly affected by dietary ARA levels. To our knowledge, this is the first study investigating the regulation of FATP gene expressions by dietary ARA. [ABSTRACT FROM AUTHOR]

A 1H NMR-based metabolomics approach was to explore the effect of ultrafiltered fish protein hydrolysate ( UF) levels on the liver and muscle metabolic profile of juvenile turbot ( Scophthalmus maximus L.). Fish protein hydrolysate ( FPH) was produced from by-products by enzymatic treatment, and UF was obtained by diluting FPH followed filtration. Fish were fed diets containing fish meal protein, which was, respectively, replaced by UF protein 0, 50, 100, 150 and 200 g kg−1 of dietary total protein ( UF-0, UF-5, UF-10, UF-15 and UF-20) for 68 days. OPLS- DA of liver and muscle showed that high levels of UF in diets may lead to corresponding tissue metabolites changes. In liver tissue, changing metabolites included dimethylamine, N,N-dimethylglycine, valine, isoleucine, leucine, arginine and alanine and were mainly involved in choline metabolism and amino acid metabolism. For muscle tissue, changing metabolites included lactate, alanine, proline, fumarate, tyrosine, histidine, cystathionine and taurine. And the metabolites were mainly involved in glycolysis and gluconeogenesis, proline metabolism and taurine metabolism. 1H NMR-based metabolomics is a useful approach to investigate different levels of UF on metabolic profile in liver and muscle tissues combined with the growth. [ABSTRACT FROM AUTHOR]

A 10-week feeding experiment was conducted to investigate the effects of different types of dietary protein hydrolysate ( PH) on growth performance, body composition, trypsin activity and serum transaminase of juvenile turbot. Four high plant protein diets contained different types of PH, fish PH ( FPH), yeast PH ( YPH), pig blood PH ( PBPH) and soy PH ( SPH), replacing 10% fishmeal of the basal diet. The basal diet with 30% fishmeal and no PH was used as the control diet (C). Each diet was assigned to triplicate groups of 30 fish. The specific growth rate ( SGR) was not significantly different between groups C and FPH, but groups C and FPH showed significantly higher SGR than other groups. The feed efficiency ratio ( FER) and protein efficiency ratio ( PER) were not significantly different among groups C, FPH and YPH, but groups PBPH and SPH showed significantly lower FER and PER than groups C and FPH. Group PBPH showed significantly higher hepatosomatic index than other groups except YPH. Fish fed YPH showed significantly lower whole-body protein content, but significantly higher whole-body lipid content than fish fed diets C, FPH and PBPH. The activities of serum GOT and GPT in group PBPH were higher than those in groups C, FPH and YPH. These results suggested that when used at a low level in high plant protein diets for juvenile turbot, FPH is a good alternative protein source and YPH also has the application potential, but PBPH and SPH can cause negative impacts on fish growth and health. [ABSTRACT FROM AUTHOR]