A Study on How Methionine Restriction Decreases the Body’s Hepatic and Lipid Deposition in Rice Field Eel (Monopterus albus)

Methionine restriction reduces animal lipid deposition. However, the molecular mechanism underlying how the body reacts to the condition and regulates lipid metabolism remains unknown. In this study, a feeding trial was performed on rice field eel Monopterus albus with six isonitrogenous and isoenergetic feeds that included different levels of methionine (0, 2, 4, 6, 8, and 10 g/kg). Compared with M0 (0 g/kg), the crude lipid and crude protein of M. albus increased markedly in M8 (8 g/kg) (p < 0.05), serum (total cholesterol, triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and non-esterified free fatty acids), and hepatic contents (hepatic lipase, apolipoprotein-A, fatty acid synthetase, total cholesterol, triglyceride, and lipoprteinlipase). However, in the serum, very-low-density lipoprotein and hepatic contents (hormone-sensitive triglyceride lipase, Acetyl CoA carboxylase, carnitine palmitoyltransterase, and mirosomal triglygeride transfer protein) decreased markedly in M8 (p < 0.05). The contents of hepatic C18:2n-6, C22:6n-3, and n-3PUFA in the M8 group were significantly higher than those in M0 (p < 0.05), and the contents of lipid droplets in M8 were higher than those in M0. Compared with M0, the hepatic gcn2, eif2α, hsl, mttp, ldlrap, pparα, cpt1, and cpt2 were remarkably downregulated in M8, while srebf2, lpl, moat2, dgat2, hdlbp, srebf1, fas, fads2, me1, pfae, and icdh were markedly upregulated in M8. Moreover, hepatic SREBP1 and FAS protein expression were upregulated significantly in M8 (p < 0.01). In short, methionine restriction decreased the lipid deposition of M. albus, especially for hepatic lipid deposition, and mainly downregulated hepatic fatty acid metabolism. Besides, gcn2 could be activated under methionine restriction.

IDENTIFIKASI DAN PREVALENSI ENDOPARASIT (Gnathostoma sp.) PADA BELUT SAWAH (Monopterus albus) DENGAN UKURAN BERBEDA YANG DIKIRIM KELUAR PROVINSI KALIMANTAN SELATAN

This study aims to determine the type of endoparasitic worm Gnathostoma sp and the prevalence that infects rice field eel (Monopterus albus) with different grades. the method used is the descriptive method. Samples were taken from 3 different farm locations (Nor Aini, Banjar Regency, CV. Karya Bersama, Banjarbaru City, and Saberiannor Banjarbaru City), as many as 120 individuals with each grade (A, B, C, and D) totaling 30 individuals. Samples were examined using the microscopic method with 3 replications on each target organ, namely liver, meat, intestines, and kidneys. The results of the examination showed that Gnathostoma sp worm cysts were found, namely only in the liver, while in the intestines, flesh, and kidneys were not found. Based on the identification of Gnathostoma sp endoparasites seen from morphological characteristics, third-stage larvae (L3) in the phylum Nematoda, cylindrical body shape, transparent body color, and blackish brown, head shape resembling a light bulb, mouth, and has anus at the end of its body. Prevalence value in grade A = 40%; B= 30%; C= 40%, and D= 30%, this includes the category commonly or ordinary which describes that the parasite usually infects fish with a prevalence value range of 30-49%. It is still possible to send rice field eels outside of South Kalimantan Province, although the results of the examination of the test samples indicated the presence of the parasite infection Gnathostoma sp..