To elucidate the genetic control for thermal resistance of the guppy, its response to high temperature was measured as the death time, at which the immature fish acclimated at 23°C died when exposed to 37°C. Using sub-population comparison, the heritability of thermal resistance was estimated at 0.183. The two-way selection for thermal resistance led to a significant difference of the death time of immature fish between the high temperature resistant population and the sensitive one. The resistant population showed a higher heterozygotic frequency at AAT-1^* and PGM-1^* locus than the sensitive population. This suggests a heterotic effect for thermal resistance and inbreeding depression for thermal sensitivity. Cross experiments confirmed heterosis for thermal resistance, supporting the above suggestion.

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To determine the effects of water temperature on the catabolic losses and condition index of unfed pearl oysters Pinctada fucata martensii, pearl oysters were held unfed at water temperatures of 15, 22 and 28°C for 60 days under laboratory conditions. Cumulative mortality was within 7% and whole weight decreased less than 7% during the experimental period. Both dry meat weight and condition index gradually decreased during the 60-day unfed period. The decreasing rate of condition index and dry meat weight increased with increasing water temperature. Therewas a positive close correlation between water temperature and catabolic lossesof dry meat weight, carbon and nitrogen content from pearl oysters held unfed for 60 days (r_??_0.93 in all instances). These results suggest that the degree ofcatabolic losses of pearl oysters depended on the ambient seawater temperature under the unfed condition. Unfed pearl oysters can survive by utilizing energy reserves from their meat for up to 60 days. However, the nutritive status of pearl oysters indicated the condition index, and the carbon and nitrogen content of drymeat declined during the unfed period, particularly at 28°C.

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To elucidate the influences of food deprivation on the mortality of the pearl oyster Pinctada fucata martensii, the pearl oysters were held unfed at an environmental seawater temperature of 23-29°C from early June to late September in 1985 (115 days). The mortality of unfed pearl oysters increased from day 70 of unfed cultivation. Cumulative mortalities reached 95% on day 115 from the start of unfed cultivation. During the unfed period, the glycogen content of adductor muscle decreased rapidly during the first week. Dry meat weight losses increased more than 70% and condition index decreased from 13.7 (initial) to 4.0 on day 70 of unfed cultivation. Crystalline style weight also decreased continuously as well as dry meat weight and condition index. On the other hand, wet meat moisture content increased from 81 to 91%.
It is thought that unfed pearl oysters can not survive when they waste their nutritive reserves and there may be a critical survival limit of pearl oysters under the unfed condition. In this study, when the condition index dropped below 4 and dry meat loss increased more than 70%, the mortality of unfed pearl oysters remarkably increased. These values may be valid indicators for the critical survival limits of pearl oysters under the unfed condition.

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The effects of water temperature on oxygen consumption rate of the juvenile oval squid
Sepioteuthis lessoniana ranging from 0.04 to 4.28g in body weight were investigated individually by a
water bottle method at 10, 15, 20, 25, and 30°C. Oxygen consumption rate in ml oxygen/indiv./h (R)
increased linearly with increase of body weight in g (W) and was expressed as R=aW^b•C^T for all temperature conditions (T), where a=0.143, b=0.929, and C=1.069 (n=202). The correlation coefficient
between R and T was 0.993, and Q₁₀ showed 1.95 within the range of 10 and 30°C. The influence of temperature on the oxygen consumption was relatively constant in the young over 0.48g up to 4.28g at temperature levels under the present investigation. However, the effect of temperature upon oxygen consumption rates was larger in the younger squid reared at a temperature higher than 20°C. The
metabolism of squid in the early stages before 0.199g is assumed to be stronglyaffected by the differences of water temperature within the range of 15-25°C.

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For cultured pearl production, a mantle allograft from a donor is implanted intoa recipient gonad together with a small inorganic bead. Encapsulation of the grafts by hemocytes follows. The mantle allograft's outer epithelial cells subsequently emigrate along the inside of the hemocyte capsule, and eventually form a follicle, called a pearl sac, surrounding the bead. To clarify thecell types involved and timing of mitotic activity in the process of pearl sac formation, pearl oysters at various phases of pearl sac formation were injected with a thymidine analog, 5-bromo-2'-deoxyuridine (BrdU), and dividing cells labeled with BrdU were visualized with anti-BrdU antibody. At 4 days after implantation, the epidermal cells (dominant cells in the outer epithelium) of the allograft initiated active proliferation and emigration. Their mitoses continued during emigration and after establishment of the pearl sac. No incorporation of BrdU into the other two types of mantle epithelial cells (mature mucous cells and cells with large granules) was observed. In the gonad surrounding the pearl sac, a large number of connective tissue cells among gonadal follicles and around the intestine showed peak mitotic activity around one week after the operation, which implied activation of hemocyte production.

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A generalization of the equations used in virtual population analysis is derivedfrom the differential equations for survival and catch. This new equation relates exactly catch to population size and contains the equations of virtual population analysis and cohort analysis as special cases. Examples are given to illustrate the flexibility and usefulness of this general equation.

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A series of light-luring fishing trials, 84 hauls for 20 days, were conducted bya commercial vessel off the west coast in the Gulf of Thailand using a stick-held cast net from March 1991-February 1992. The mean catches were approximately constant, about 16kg/haul, in a range of light-luring times from 1.5h to 5.5h. When haul by haul catches decreased, it was clearly shown that the larger squid in a shoal were captured preferentially. However, there did not appear to be any considerable changes in the size structures of squid caught by successive hauls, when haul by haul catches increased or decreased. The number of squid aggregated into the lit area was estimated to be about 1, 000-3, 000. The efficiency of the cast net may be a function of the number of squid, or in other words, a low catch efficiency might be caused mainly by dispersion of shoals at low density or by gear aturation at high density.

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Underwater fish loss in vertical longline fishing was assessed with emphasis on injury of unharvested fish. Two series of experimental fishing were conducted in tropical deep water. The capture process was statistically modeled and ratios of contact, hooking and fish-loss, which includes escape of hooked fish and breaking branch lines, were found to depend on the gear-soaking time orhook height from the sea bed. A simulation using a model estimated that fish loss was 1.07 times morethan the catch when the tested line maximized the catch under the tested condition. The fish-loss/catch ratio increases rapidly with longer soaking of the gear. To reduce fish loss, vertical longlines with fewer hooks at short vertical intervals must be used to maximize the catch at a short soaking. In richerfishing grounds, the optimum soaking period is shorter, the catch per line increases and fish loss decreases, therefore, only a small number of lines is needed to maximize the catch. The development of fishing with an increasing number of hooks may accelerate fish loss as resources dwindle. The technical transfer of longlining to developing countries whose fishing grounds are mostly under-developed must be reevaluated.

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The process of downstream migration and maturation of the Japanese mitten crab Eriocheir japonicus was determined by investigating the relationship between gonad maturity and the distribution of E. japonicus in the Kaminokawa River, Kagoshima, Japan. In females, migration occurs following the puberty moult. Gonad maturation occurs after the puberty moult, taking approximately 4 months. The gonadosomatic index (gonad weight×100/cheliped-free body weight) increased from below 1.0 to above 10.0. With maturation, oocyte diameter increased from less than 60 μm to more than 300 μm. However, crabs migrated downstream even if they had not necessarily completed maturation. The migration appears to end earlier further upstream and there are two seasonalperiods of maturation. The early maturing group, which was small in number, developed ovaries in September or October and oviposited in October. In the late maturing group which was larger in number, puberty moulting occurred in August, and maturation ended nearly in December and oviposition occurred after December. The early group tended to be larger. In males, the GSI was always below 1.0, and tended to increase from March to August. Most crabs seemed to migrate downstream in the mature condition with their vas deferens full with spermatophores. The maturity size tended to belarger for individuals from further upstream.

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Spawning habitat and nest depth in relation to female body size were studied in a small population of Dolly Varden Salvelinus malma. Females selected areas where gravel was prevalent and currents were slow for spawning. Neither substrate score, water depth, nor current velocity was significantly correlated with the female body size. Nest depth, however, was strongly correlated with female size. These results suggest that nests made by smaller females are more vulnerable to destruction both from flooding and from nest site reuse by later-spawning females.

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Distribution and seasonal fluctuation of the bacteria which inhibit the growth of a red tide marine dinoflagellate Gymnodinium mikimotoi, were surveyed in Tanabe Bay (Wakayama Pref., Japan), using the newly developed MPN method with an axenic culture of G. mikimotoi. G. mikimotoi's growth inhibiting bacteria (Gm-GIB) were detected at 10³-10⁴ cells/ml before occurrences of huge red tides by G. mikimotoi at the beginning of August in 1990 and from the end of August to the beginning of September in 1991. The number of Gm-GIB fell by about two orders of magnitude at the blooming periods of G. mikimotoi, and then increased again after the blooms declined. These results suggest that the fluctuation of Gm-GIB counts in seawater is significantly related to the developmentand decline process of G. mikimotoi red tide. Forty strains of Gm-GIB isolated in this study all acted as killers against this dinoflagellate rather than as suppressers on the algal growth under laboratory conditions. The precise causes of the fluctuation of Gm-GIB in seawater environments remain unknown.

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Immunoglobulins in the oocytes, fertilized eggs, and yolk sac larvae of red sea bream were successfully detected by SDS-PAGE and Western blotting, using rabbitantibody against red sea bream blood IgM. Those immunoglobulins appeared structurally identical to the blood IgM of the mother fish, based on the same molecular weight of their H and L chains to those found for the blood IgM, 78 kDaand 26 kDa respectively. Referring to the oocytic immunoglobulin, this appeared in the early stage ofvitellogenesis before the spawning season and was also present in reproductively active ovaries during spawning. Those observations indicate that immunoglobulin existing in the mother's blood can be transferred to its oocytes and subsequently to eggs and yolk sac larvae in red sea bream.

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The IgM concentration and specific antibody titre of oocyte and egg extracts of Vibrio-immunized red sea bream were successfully measured by an enzyme immunoassay and an ELISA procedure. The concentration of oocytic immunoglobulin was found to increase during the vitellogenesis process. The oocytes as well as the fertilized eggs of the immunized females had antibody titre much higher than that of the control group. On the other hand, no considerable difference in immunoglobulin concentration was found between the eggs obtained from immunized and control mothers. Hence, the comparison of the value of antibody titre per mg IgM estimated for the maternal blood, oocytes and eggs of the same fish showed that common features of immunity exist between the oocytes, eggs and maternal blood. The possible origin of the oocytic and egg IgM was shown to be the maternal blood plasma.

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The efficacy of enteric-coated microcapsule was tested for enhancement of uptakeof orally administered protein in eel Anguilla japonica.
Bovine serum albumin (BSA) was used as marker protein and was encapsulated by cellulose acetate phthalate microcapsule. The transported volume of BSA in the serum collected 48 hours after oral intubation was detected by the Ouchterlony and single radial immunodiffusion (SRID) tests using rabbit's antiserum against BSA.
The results indicated that BSA was transported into the blood stream through the digestive tract at least when a large volume of BSA was administered. However, the rate of positive reactions and the transported volume of protected BSA were larger than that of unprotected BSA especially when the administered doses were low. These observations show that it is possible to apply the enteric-coated microcapsule for practical oral vaccination of fish.

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Effects of L-tryptophan and related compounds on larval settlement of barnacle Balanus amphitrite Darwin were examined. The settlement rate of young cyprids increased in proportion to L-tryptophan concentration (1.8×10^-5M to 5.6×10^-4M). The inducing effect of serotonin (5-hydroxytryptamine; 5-HT) on larvalsettlement was similar to that of L-tryptophan at the concentration range of 3.4×10^-7M to 1.1×10^-5M. When 5-HT was applied to old cyprids, however, no inducing effect of larval settlement was observed. On the other hand, reserpin, a depleting agent of neuroactive amines such as 5-HT in mammals, showed inhibitoryactivity on settlement of old cyprids at the concentration of 10^-7M.

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The effect of the unfrozen phase under frozen storage conditions on the solubilty and ATPase activity of carp myofibrils was compared. Myofibrillar samples were suspended in 0.1M KCl solution containing 5 and 20mM Tris-maleate buffer (pH 7.2), and in 0.1M KCl solution without a buffer. Sampleswere stored at threedifferent temperatures, -4, -11, and -26°C. When the decrease in ATPase activitywas larger than that of the soluble protein during storage above and nearthe eutectic point of KCl (at-4 and -11°C), and in the presence of 20mM Tris-maleate buffer, it is assumed that the myofibrils are greatly affected by a small amountoof concentrated KCl solution. However, in the absence of a buffer, Where the opposite occurs in both indices, the denaturation of myofibrils is thought to be caused largely by the moving closer together and maldistribution of protein molecules. This is possible to explain in terms of the amount of unfrozen solution being sufficient for maldistribution, but insufficient for inactivation. On the other hand, when stored below the eutectic point of KCl (at-26°C), the decrease in both indices was smaller than that seen in samples stored at -4 and -11°C.This could be ascribed to the fact that myofibrillar protein and crystallized KCl are dispersed uniformly due to the small amount of unfrozen solution, insufficient for bothmaldistribution and inactivation. The surface hydrophobicity was increased in the early stages of storage at both-4°C and-11°C.

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The changes of subunit components in salt (0.6M KCl)-soluble and salt-insolublfractions of carp myofibrils during frozen storage were followed by 7.5% polyacrylamide gel electrophoresis. Myofibrillar samples were suspended in 0.1M KCl solution containing 5 and 20mM Tris-maleate buffer (pH 7.2), and in 0.1M KCl solution without a buffer. Prepared samples were stored at three different temperatures: -4, -11, and-26°C. When the solubility decreased after 2-3 weeks at-4 and-11°C, the main components of the myofibrils in the salt-soluble fraction decreasedand weredetectable in the saltinsoluble fraction. The decrease of salt-solubleprotein at-11°C was larger than that observed at -4°C. At -4°C storage, theextentofthe decrease in the salt-soluble fraction and consequently that of the increasein the salt-insoluble fraction was relatively larger in the actin (A) component than in the myosin heavy chain (HC) component. At -11°C storage, the shift of HC component from the salt-soluble fraction to the salt-insoluble fraction on the last day of storage was larger than that of the A component in three Tris concentrations. As for the salt-insoluble fraction, the aggregated proteins which could not migrate into 7.5% polyacrylamide gel (>G component) was foundto be largerin th model system without the buffer than in that containing the buffer at any storage temperature. It seems that the formation of the >G component at-11 and-26°C without buffer accompanied the HC component.

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The effect of grilling of marine fish products on the oxidation of cholesterol was investigated by using seveyral kinds of salted-dried and boiled-dried marine fish products. The contents of total lipids decreased slightly in most of samples. However, no remarkable differences in the contents of residual cholesterol were observed before and after grilling. In the marine fish products rich in eicosapentaenoicacid (EPA) such as dried products made from Japanese whiting, squid buccal mass and northern cod, the decrease in the levels of polyunsaturated fatty acids (PUFA) after grilling was fairly large. Contrary to this, in the products withthe lower levels of EPA such as salted-dried Pacific round herring and fermented-dried horse mackerel, the decrease in the level of PUFA was relatively small. 7β-hydrox-ycholesterol, 7-ketocholesterol, α-epoxide, β-epoxide, cholestane triol, and 25-hydroxycholesterol were found as cholesterol oxides in the samples used in the present study.
For the fatty fish products such as the salted-dried Pacific round herring and the salted-dried Japanese whiting, the total amounts of cholesterol oxides increased after grilling. Contrary to this, no remarkable changes were observed in the processed foods produced from lean fish.

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The relationships between carp muscle tension in rigor and the tension induced by permeation of water or CaCl₂ solution were investigated. Initial weight increase of fish muscle in water corresponded to initial tension development, and the occurrence of tension shoulder was caused by water permeation into the muscle. In the stressed fish muscle, osmosis did not cause a rapid permeation of the surrounding water into the hypertonic muscle due to the generating contractile tension. Within the immersiontime of 14-19 min required for calcium-induced tension peak, arapid permeation of the CaCl₂ solution into the muscle was observed. The tension at a high level of ATP and calcium ion was greater than the rigor tension at a low ATP level with water permeation. The rigor tension and the permeated calcium-induced tension declined but the water-induced tension did not decline. The changeof ATP/IMP absorbance ratio obtained for the extract from the surface and insideof the muscle in water during postmortem immersion was almost the same as that for the extract of muscle fillet during postmortem storage. The development of water-induced tension was ascribed to the swelling effect which was caused by the permeation of water into the muscle.

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A 6-week feeding experiment was conducted to determine the optimum combinationalratio of soybean meal (SBM) and malt protein flour (MPF) as alternative proteinsources of fish meal in fingerling rainbow trout diets. In the control diet, brown fish meal (BFM) was used as the sole protein source to be 43% crude protein. In the experimental diets, 60% of BFM protein was replaced by proteins from SBM and MPF. The combinational ratios of SBM and MPF were varied as 60:0, 40:20, 30:30, 20:40, and 0:60 in the percentage of total dietary protein. In the fish fed the diet with the ratio of 30:30, almost similar levels of weight gain and protein retention with the control diet were noted, and moreover theenergy retention based on digestible energy was higher than that of the control. These findings suggest that an equivalent combination of both alternative proteins can maximize the rearing performance of fingerling rainbow trout.

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Feeding stimulants for the tiger puffer Takifugu rubripes were identified by omission test using the synthetic clam Tapes japonicus extract, based on a daily feeding rate for casein diet with each test solution. The amino acid fraction showed remarkably higher feeding stimulant activity than those of nucleotide and other chemical fractions in the extract. Among 18 chemicals in the amino acid fraction, L-serine, L-aspartic acid, glycine, and L-alanine showed slightly higher activity than deionized water, but lower than the amino acid fraction. The mixtureof the above four amino acids plus betaine showed a markedly higher feeding stimulant activity than that of the synthetic extract, indicating the synergistic effect. The positive supplement level of the four amino acids plus betaine was foundto be that corre-sponding to 100g of clam muscle per 100g of casein diet.

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Tiger puffer Takifugu rubripes, weighing about 10g, were reared for 28 days onbrown fish meal diets containing 10, 13, 16, 19, and 22% white dextrin.
Except for a low survival (75%) obtained in the fish reared on the lowest whitedextrin diet, the fish reared on other diets and sandeel, as a reference, showed high survival (>95%). Under a similar daily ration size, the best weight gain, feed efficiency, and protein efficiency ratio were commonly noted in the fish fed the 16% dextrin diet. No marked differences among the dietary treatments were found in the proximate compositions of whole body and the hepatopancreas. Apparent digestibilities of dietary carbohydrate and protein remained high in the fish given 13-16% and 10-19% dextrin diets, respectively, using the intestinal digestadissected at 5 h after feeding.
These results indicate that a suitable dietary dextrin level for the puffer is estimated around 16% and dietary carbohydrate content about 20%.

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Tiger puffer Takifugu rubripes, weighing about 3.7g, were reared for 20 days on brown fish meal diets with graded levels of pollack liver oil, 0, 2.5, 5.0, 7.5, and 11.0%.
The best feed efficiency, protein efficiency ratio, and apparent protein retention were obtained in the group fed the diet with 7.5% oil. Otherwise, there appeared to be no significant differences in weight gain and fatness among the dietary treatments under isocaloric ration size. Moreover, protein sparing effect was also observed in the groups fed the diets with 7.5% oil, sparing about 11.5% of dietary protein for 100g of weight gain compared with the puffer fed the diet without oil.
These results indicate that a suitable dietary level of pollack liver oil for the puffer is estimated to be around 7.5%, namely dietary crude fat of about 11.5%, when 48% brown fish meal, 10% wheat gluten, and 17% white dextrin are used as protein and carbohydrate sources.

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Changes in the activity of two histidine decarboxylases from Photobacterium phosphoreum during the growth of different oxygen tensions and some properties of the enzymes were studied. The specific activity of the enzyme of crude extract was highest in the anaerobic stationary culture and higher in the aerobic stationary culture than in the aerobic shaking culture, in contrast withgrowth. The pattern of variation of the specific activity during growth differed between the anaerobic and aerobic stationary cultures and the aerobic shaking culture. The enzyme was composed of at least two enzymes with molecular weights of about 700, 000 (peak I) and 107, 000 (peak II). Peak I was considered as constitutive enzyme and peak II as inducible enzyme. The enzyme of peak I was labile butthat of peak II was stable in the presence of dithiothreitol (DTT). The activities of peaks I and II varied with different oxygen tensions of the culture; the percent activity increased in peak I but decreased in peak II with increasing oxygen tension. Therefore, it has been suggested that the histamine-forming ability is affectec by the quality as well as the quantity of enzyme.

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The emulsifying activity of sarcoplasmic protein (Sp-P) from sardines was evaluated in connection with heat-treatment. The solubility of sardine Sp-P decreased with a rise in heating temperature over 40°C when heated at various temperatures from 20 to 100°C for 15 min at pH 7.0. After the heat treatment at a temperature above 60°C, the Sp-P was insolubilized up to 95%, and thesoluble fractions were composed mainly of a component of ca. 12 kDa, parvalbumin. The soluble proteins from the higher temperature abuse showed excellent emulsifying activity. The emulsifying activity of the parvalbumin fractions prepared from Sp-P by Sephadex G-75 chromatography was greater than that of the other protein fraction of Sp-P at equal concentration (1mg/ml) and did not decrease on heating at 80°C for 15min. The parvalbumin fraction is considered to play an important role in the emulsification process with water-soluble proteins from sardines.

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A multi-enzyme system was immobilized in a β-chitin membrane. β-Chitin was obtained from common squid pens and glutamate pyruvate transaminase and pyruvate oxidase were immobilized simultaneously in the β-chitin membrane. The immobilization was achieved by filtration of the chitin suspension containing enzymes without any chemical reagent or pH treatment. An enzyme electrode for the measurement of L-alanine was assembled with the β-chitin membrane and an oxygenelectrode, and enzyme activities were evaluated. A control membrane was prepared using a cross-linking method with enzymes, bovine serum albumin and glutaraldehyde. The electrode response of the β-chitin membrane was obtained immediately after the sample injection and leveled off in 60 s. In contrast, the control membrane showed a slower response. The maximum response of the β-chitin embrane electrode was obtained at 38°C and pH 7.1. Linearity of the calibration curve was obtained up to 30mM in the batch system and 200mM in the flow system. These results suggest that β-chitin is a useful supporting material for enzyme immobilization and applicable to enzyme electrodes.

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A 3×3 factorial experiment was conducted using three levels of supplemental L-ascorbyl-2-phosphate-Mg (APM) 0, 10 and 1, 000mg/100g of diet and three levels of n-3 highly unsaturated fatty acids (n-3 HUFA) 0, 1 and 2% of diet on Japanese flounder Paralichthys olivaceus juveniles (initial body weight 0.35g). Average body weight was about 6-7g over a 50-day period of feeding in the APM-supplemented groups with 1 and 2% of n-3 HUFA, these groups showed higher weight gain and feed conversion efficiency than in the APM-unsupplemented groups. Analysis of variance on weight gain, feed conversion efficiency and concentration of ascorbic acid in the liver revealed that there were significant (p<0.05) interactions between APM and n-3 HUFA levels. The fatty acid composition of total lipid in whole-body, neutral and polar fractions in the liver almost mirrored that of thedietary lipids. Inspite of the APM level, there was no marked difference among the groups of diets with thesame level of n-3 HUFA. Regardless of n-3 HUFA level in the diets, the total lipid concentration in whole-body and liver generally increased due to the accumulation of triglyceride when the APM level increased.

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The glutathione peroxidase activity (GHS-P_x) in eleven blood specimens of two species of tuna, i.e., nine individuals of yellow fin tuna Thunnus albacares and two individuals of big-eyed tuna Thunnus obesus, and in seven blood specimens of four species of marlin, i.e., three individuals of striped marlin Tetrapturus audax, two individuals of blue marlin Makaira mazara, one individual of swordfish Xiphias gladius and one individual of sailfish Istipohorus platyterus, are presented in relation to the distribution of selenium and mercury.
GSH-P_x in the blood of tunas was high compared with that of marlins, as in the cases of the selenium and mercury concentrations. In both species, GSH-P_x did not significantly correlate with the concentration of the low oxidation state of selenium. On the other hand, GSH-P_x correlated netatively with the total mercury concentration in the case of marlins while there was no correlation in the case of tunas. These findings may suggest that since there are few protein-containing selenohydryl groups with mercury as organic selenium in the blood of marlins, GSH-P_x tends to drastically decrease with mercury accumulation.

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Troponin, which confers high Ca²⁺-sensitivity to rabbit reconstituted actomyosin, was isolated from the abdominal muscle of prawn Penaeus japonicus. SDS-polyacrylamide gel electrophoresis showed that the prawn troponin consists of three components of Mr 17, 000, 30, 000-32, 000 (doublet), and 42, 000 in a molar ratio of 1:1:1, but Mr 52, 000-59, 000 component, which had been reported to be a troponin-T-like protein in arthropod troponin, was not found. The three components were separated from each other by DEAE-Toyopearl column chromatography in the presence of 6M urea, and assigned as troponin-C, troponin-I, and troponin-T in increasing order of molecular weight. These features were basically identical with those of American lobster troponin of our previous study (Nishita and Ojima, J. Biochem., 108, 677-683 (1990)).

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Measurement of chitinase, β-N-acetylhexosaminidase, and lysozyme activity in 98species of seaweed were carried out. Chitinase activity was detected in 30 species of Rhodophyta and 1 species of Phaeophyta. β-N-acetylhexosaminidase activity was found in 11 species of Rhodophyta, 2 species of Phaeophyta, and 3 species of Chlorophyta. No lysozyme activity was detected in any of the species. Optimum pH of chitinase was observed to be pH 3.5 and 9.0 in Chondrus giganteus and pH 4.0 in Gigartina mikamii and optimum temperature was observed to be 60°C in both species. Activity was lost in Chondrus giganteus and was decreased to 20% in Gigartina mikamii by heat treating for 60min at 80°C. These properties resembled those of chitinase found in higher plants.

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