Hepatopancreas Of Prawn Research Articles

Phospholipid fatty acid composition of hepatopancreatic brush-border membrane vesicles from the prawn Penaeus japonicus

Brush-border membrane vesicles (BBMV) were isolated from prawn hepatopancreas as we previously described (Muriana et al (1993) J Biochem 113, 625–629). The characterization of hepatopancreatic BBMV (hBBMV) by monitoring the activity of marker enzymes indicated a relatively pure apical membrane preparation reduced in basolateral contamination. Phospholipid composition of hBBMV was examined by the Iatroscan TLC/FID technique, whereas the fatty acid profile of phospholipids was examined by capillary gas chromatography. Phosphatidylcholine and phosphatidylethanolamine are the principal phospholipids of these membranes. The major fatty acids of phospholipids are palmitic (16:0), palmitoleic (16:ln-7), stearic (18:0), oleic (18:ln-9), eicosapentaenoic (20:5n-3) and docosapentaenoic (22:5n-3) acids. Individual phospholipids are characterized by distinct fatty acid composition, but display a similar ratio of unsaturated-to-saturated fatty acids and a similar unsaturation index.

Lipid and Fatty Acid Composition of Hepatopancreatic Brush-Border Mambrane Vesicles from the Prawn Penaeus japonicus1

Brush-border membrane vesicles (BBMV) were isolated from prawn hepatopancreas by a procedure involving Mg2+ preparation. The lipid composition of hepatopancreatic BBMV (hBBMV) was examined by the Iatroscan TLC/FID technique, and the fatty acid profile of total lipids was determined by capillary gas chromatography. hBBMV were characterized by a high content of phospholipids and cholesterol. However, the cholesterol/phospholipid molar ratio is lower in prawn than in vertebrate BBMV, which agrees well with the membrane fluidity of BBMV from different sources. The fatty acid composition of hBBMV was similar to that in marine crustacean oils. The major fatty acids present were palmitic (16:0), palmitoleic (16:1n-7), stearic (18:0), oleic (18:1n-9), and eicosapentaenoic (20:5n-3) acids. The large amount of long-chain polyunsaturated fatty acids seems to be related to a high delta 5-desaturase activity in hBBMV.

17β-Hydroxysteroid Dehydrogenase Activity of Ovary and Hepatopancreas of Freshwater Prawn, Macrobrachium rosenbergii: Relation to Ovarian Condition and Estrogen Treatment

The activity of 17β-hydroxysteroid dehydrogenase (17β-HSD) was determined in the hepatopancreas anti the ovary of freshwater prawn Macrobrachium rosenbergii , at different stages of life. A uniform level of 17β-HSD activity was observed in the hepatopancreas of immature, maturing, matured, and gravid prawns, whereas the activity of this enzyme was found to be higher in the ovary of the maturing prawn only. Gradual increases in the GSI values and ovarian protein content at the different stages of maturity were observed in this animal. Between the two organs, higher activity of 17β-HSD was observed in the hepatopancreas of the prawn in the maturing stage. The estradiol-17β (E2) level measured by radioimmunoassay showed its peak in both the hemolymph 126.0 ± 7.0 pg/ml) and the ovary (300.00 ± 9.0 pg/mg protein) in the maturing prawn only compared to that in immature, matured, and gravid prawns. The hormone level became undetectable in the hemolymph and remained about 10-fold less (30.6 ± 5.0 pg/mg protein) in the ovary of the gravid prawn in comparison to the prawns in the maturing stage. A parallelism between the nature of 17β-HSD activity and the hormone level was observed in the ovary at different stages of life. A dose-dependent stimulation of 17β-HSD activity was observed in the hepatopancreas of the maturing prawn after three consecutive injections of 0.25. 0.5, 1.0, and 2.0 μg/g of estradiol-17β (E2) on the 4th day of treatment compared to the control values. E2 at a higher dose (4.0 μg/g) caused only a little stimulation of 17β-HSD activity in this organ. The ovary of the maturing prawn showed a higher degree of responsiveness to E2 by increasing the activity of 17β-HSD in a dose-dependent manner, in the range of 0.05, 0.1, and 0.25 μg/g doses. A graded inhibition of the enzyme activity was observed in the ovary with higher doses of E2 (0.5, 1.0, and 2.0 μg/g). The E2-induced increase of 17β-HSD activity was neutralized by concurrent use of tamoxifen and cycloheximide. The present study suggests that the endogenous and E2-inducible nature of steroid metabolism probably through increased biosynthesis of 17β-HSD in the hepatopancreas and the ovary of the maturing freshwater prawn has a reproductive role.

Study of the proteolytic activity of the hepatopancreas of the freshwater prawn, Macrobrachium rosenbergii, and its role in inducing mushiness in muscle tissue during post-mortem storage

The proteolytic activities of crude homogenates from the hepatopancreas of the prawn Macrobrachium rosenbergii were investigated. The caseinolytic and haemoglobin-hydrolysing activities are mainly due to thiol proteases with a minor contribution of trypsin-like activity. The hepatopancreas proteolytic activity is less efficient than trypsin in degrading myofibrillar proteins in intact tissue. The collagenolytic activity in the homogenates differs in substrate specificity from bacterial collagenase. The specificity of these enzymic activities and their relation to mushiness in prawns stored in ice are discussed.

Lipid metabolism of the prawn Penaeus japonicus during maturation: Variation in lipid profiles of the ovary and hepatopancreas

Abstract 1. 1. Lipids (TL) were extracted from the ovary and hepatopancreas of prawns, Penaeus japonicus, with varying degrees of ovarian maturation and were analysed for lipid class composition, fatty acid composition of triglycerides (TG) and phosphatidylcholine (PC), and possible fatty acid combination of PC and phosphatidylethanolamine (PE). 2. 2. The concentrations (% of fresh wt) and quantities (mg/prawn) of ovarian TL increased slightly and drastically, respectively, with increasing maturity in terms of gonadosomatic index (GSI). TG, PC and PE were the major lipid classes responsible for increases in the quantity of ovarian TL during maturation. 3. 3. In the ovary and hepatopancreas, as ovarian maturation proceeded, TG showed increases in the proportion of monoene fatty acids such as 16:1 and 18:1, whereas PC exhibited increases in the proportion of highly unsaturated fatty acids such as 20:5ω3 and 22:6ω3 with a concomitant decrease in 16:0 and 16:1. 4. 4. No marked variation was found in the proportion of the possible fatty acid combinations, in terms of carbon numbers, of both ovarian PC and PE during maturation.

Properties of two chymotrypsins from the digestive gland of prawn Penaeus monodon

For the first time chymotrypsins have been isolated from the hepatopancreas of prawn. Two purified chymotrypsins from Penaeus monodon were found to be single-chained with molecular masses of 27 and 26 kDa, respectively. They have chymotrypsin-like specificities, and cleave the insulin chain B preferentially on the carboxyl side of tyrosyl, phenylalanyl and leucyi residues. They were effectively inhibited by soybean trypsin inhibitor, turkey and chicken ovomucoid, chymostatin, PMSF, Z-AlaGlyPhe chloromethyl ketone but not by Z-Phe chloromethyl ketone and many other small protease inhibitors. The shrimp enzymes hydrolyze protein substrates as rapidly as but small substrates much slower than bovine chymotrypsin, suggesting the importance of an extended substrate interacting site.

Metabolism of [ 14C]β-sitosterol injected at various stages of the molting cycle in prawn Penaeus japonicus bate

1. 1. Certain aspects of β-sitosterol metabolism at various stages of the molting cycle in the prawn Penaeus japonicus Bate were studied. 2. 2. The radioactivity (dis/min) per mg of tissue or organ of prawn injected with [ 14C]β-sitosterol was very high in the gonads and hepatopancreas, high in hypodermis at stages A–B, C 1–C 2, C 3–C 4, D 1–D 2; and high in the gonad, hypodermis and hepatopancreas at stage D 4. 3. 3. The rate of bioconversion of β-sitosterol to cholesterol in the hepatopancreas of prawn at stage A–B, three days after injection, was 30–40%. 4. 4. Thin-layer chromatographic analyses of lipids indicated the presence of free sterol, steryl ester and polar steroid in all the tissues and organs. Free sterol was predominant, accounting for 75.7–97.4% of the radioactive compounds present.

クルマエビの精製合成飼料 Ｖ カゼイン分解物を窒素源とする飼料による飼育試験

Subsequent to the previous work, casein hydrolyzates obtained by treatment with pepsin, trypsin or the lyophilized hepatopancreas of prawn were compared with intact casein as a nitrogen source of diet for the prawn, Penaeus japonicus, by a feeding experiment. Casamino acids (DIFCO) and casitone (DIFCO) were also tested. The level of nitrogen source was 52.5% in all test diets. In a 4-week feeding trial, all test diets containing casein hydrolyzates resulted in poor growth and high mortality. These results suggest that peptides as well as free amino acids are far inferior to protein as a nitrogen source in the prawn diet.