• Journal of Aquaculture
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• v.16 no.4
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• pp.233-239
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• 2003

Growth and activities of digestive enzymes in slime flounder (Microstomus achne) larvae were measured from hatching to near the end of larval development (day 58). Larvae reared under starved and fed conditions and the changes of acid phosphatase (ACPase) specific activity, alkaline phosphatase (ALPase) specific activity, trypsin-like enzyme activity and pepsin-like enzyme activity were described with growth and developmental stage of larvae. Total length of the starved larvae was gradually increased for 7 days post hatching and then almost unchanged. Total length of the fed larvae ranged from 5.13$\pm$0.178 mm at the day of hatching to 13.43$\pm$1.395 mm at 58 days after hatching. In starved group, dry body weight decreased from 0.l0$\pm$0.020 mg at the day of hatching to 0.05$\pm$0.012 mg at 12 days after hatching. Dry body weight of fed larvae decreased during the prelarva stage like starved group and then gradually increased. ACPase and ALPase specific activity in the starved larvae increased until all larvae died, however those activities in the fed larvae increased until 20 days and then decreased until 58 days after hatching, with no significant difference between groups. Trypsin-like enzyme activity in the starved larvae was unchanged until 3 days and then was the highest on 5 days after hatching, but not detected after completion of yolksac absorption. Those of fed larvae decreased until 3 days and sharply increased until completion of yolksac absorption. The highest trypsin-like enzyme activity in the fed group was observed at 20 days after hatching. Trypsin-like enzyme activity in the fed larvae was significantly higher than that in the starved larvae from 8 days after hatching. Pepsin-like enzyme activity was increased in 5 days after hatching in both groups. There was significant difference at 8 and 10 days after hatching between both groups. Based on above results, digestive enzyme activities were correspondingly changed to a growth and morphological transformation. Trypsin-like enzyme and pepsin-like enzyme activities are able to be a useful indices for health and growth status in larval slime flounder, because there was significant difference in digestive enzyme activities with developmental stages, growth or feed supply.

• Korean Journal of Ichthyology
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• v.21 no.3
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• pp.149-157
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• 2009

Larvae and juveniles of the filefish Thamnaconus modestus were reared for 64 days after hatching (DAH) in order to determine the activity of four enzymes (trypsin, pepsin-like enzyme, lipase, amylase) during ontogeny. Larvae were fed on rotifer Brachionus plicatilis from 2 to 26 DAH, Artemia nauplii from 10 to 64 DAH, and then gradually changed to pelleted feed from 40 DAH. Temperature was kept between $21.5{\sim}24.2^{\circ}C$ Activity of trypsin and lipase was found in larvae 4 DAH ($6.0{\pm}1.4unit$) and 6 DAH ($4.5{\pm}1.4unit$), respectively. The evolution of activity in both enzymes showed a profile marked by drastic increases between late larval and early juvenile stages. Pepsin-like enzyme activity was found at 10 DAH and drastically increased from 28 DAH, corresponding with the early juvenile stage of T. modestus. Interestingly, developmental changes in the pepsin-like enzyme activity coincided well with increases in the number of gastric glands. Amylase activity was found at 10 DAH and was maintained at a low level up to 28 DAH, followed by a drastic increase from 28 DAH to 40 DAH. It might be concluded that a drastic increase in trypsin and pepsin-like enzyme activities, and a corresponding increase in the number of gastric glands reflects a higher somatic growth of T. modestus during the early juvenile period.

• Journal of Aquaculture
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• v.19 no.2
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• pp.125-132
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• 2006

Black rockfish larvae and juveniles were reared for 95 days after parturition (DAP) in order to determine four enzyme activities (trypsin, pepsine-like enzyme, lipase, amylase) during ontogeny. Larvae were fed rotifers Brachionus plicatilis from 1 to 25 DAP, Artemia nauplii from 10 to 78 DAP and then gradually changed to pelleted feed from 30 DAP. Temperature was kept between $13.5{\sim}14.9^{\circ}C$. Trypsin and lipase activities were found in 2 DAP larvae ($7.0{\pm}1.5$ unit and $4.5{\pm}1.4$ unit, $mean{\pm}SD$, respectively). The evolution of both enzymes activities showed a profile marked by drastic increases between postflexion and juvenile stage. There is an increment on specific trypsin activity at 10 DAP, corresponding with the beginning of Artemia feeding. Pepsin-like enzyme activity was found at 11 DAP and increased drastically from 56 DAP, cor-responding with the initiation of juvenile stage. Amylase activity was also found at 11 DAP and maintained at a low level up to 38 DAP followed by a drastic increase from 39 DAP to 50 DAP. Considering our results of both trypsin and pepsin-like enzyme activities, it might be concluded that higher somatic growth of Sebastes inermis could be possible with the initiation juvenile of stage and the early juvenile stage is a suit-able period for feeding an artificial diet for fish.

• Applied Biological Chemistry
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• v.35 no.6
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• pp.501-506
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• 1992

Pepsin-catalyzed hydrolysis and plastein reaction were carried out to prepare plastein product from soymilk residue protein. Conditions required for optimal hydrolysis of soymilk residue protein and subsequent plastein production were investigated. The optimum substrate concentration, enzyme-substrate ratio, pH, reaction temperature and incubation time for hydrolysis were 3%, 1/50, 1.7, $45^{\circ}C$ and 24 hours, respectively. Plastein formation from peptic hydrolysate of soymilk residue protein was most effective at substrate concentratin of 40%, pH 4 and $45^{\circ}C$. Reaction time of 18 hours and enzyme-substrate ratio of 1/100 were selected for plastein production. Electrophoresis of the products revealed that protein-like substances of high molecular weight were produced from the plastein reaction.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.4
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• pp.458-465
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• 1999

Distribution of the proteolytic activities of crude pretense extracted from the viscera of ten kinds of fish was examined. Their proteolytic activities on proteinous substrates (azocasein, hemoglobin, and casein) from the viscera of anchovy, bastard flatfish, mackerel and red sea bream were higher than those of other fishes, and the crude pretenses were further fractoinated with acetone or ammonium sulfate. Optimum concentrations for pretenses fractionation were $0\~55\%$ for acetone and $30\~70\%$ for ammonium sulfate. The fractionated viscera pretense of mackerel showed the highest proteolytic activity among four kinds of fishes. Activities of cathepsin D- and pepsin-like enzymes at pH 3.0, cathepsin L-, B-, H- and G-like enzyme at pH 6,0, and Hypsin- and chymotrypsin- like enzymes (pH 8.0) were detected in the fractionated viscera pretense, whereas activities of cathepsin L- and chymoeypsin-like enzyme were observed in commercial pretenses. Proteolytic activities of Alcalase, Protamex, and Aroase AP-10 for azocasein were slightly higher than the fractionated viscera pretenses, but their amidolytic activities at pH 6.0 and 8.0 toward synthetic substrates were lower than counterpart. The fractionated pretenses from fish viscera would be utilized as commercial pretenses.