Spisula Sachalinensis Research Articles

Life cycle in adult stage of the Sakhalin surf clam in Sendai Bay.

Life cycle in adult stage of the Sakhalin surf clam Spisula sachalinensis in Sendai Bay was studied based on the interrelation between reproductive and feeding cycles. The reproductive cycle is inversely related to the water temperature. Reproduction (gonad growth and spawning) occurs primarily under the low temperature regime and the reproductive activity stops after spawn-ing for about six months during summer-autumn. Seasonal change in weight of the digestive organs is caused by the active feeding in winter-spring. The life cycle of surf clam may comprise of two phases: phase of high activity (Dec.-May) and that of low activity (June-Nov.). The synchronism between gonad growth and active feeding is the essential trait of life cycle of the surf clam, suggesting that resources from outside is directly used for the gonad growth without temporary reservation. The surf clam in Sendai Bay seems to concentrate its activity in winter through the process of adaptation to the environment.

A study of the pattern of action of endo-(1→3)-β- d-glucanases from marine bivalves on a polymer substrate labelled at the reducing end

The pattern of action of L-IV and L-O endo-laminarinases (EC 3.2.1.6) from the crystalline style of the marine bivalves Spisula sachalinensis and Chlamys albidus, respectively, on Smith-degraded laminarin labelled with 3H at the reducing end has been studied. The average d.p. of the substrate was 25. On the basis of relative bond-cleavage frequencies. The L-IV enzyme was shown to attack the substrate molecule more than once per encounter. The degree of this repetitive attack and the subsite affinities of the aglycon part of the active centre of both (1→3)-β- d-glucanases have been evaluated.

Mode of action of endo-(1→3)-β- d-glucanases from marine molluscs on the laminarin from Laminaria cichorioides: The structure and the inhibitory effect of the resulting (1→3;1→6)-β- d-gluco-oligosaccharides

The oligosaccharides released by the action of endo-(1→3)-β- d-glucanases from the marine molluscs Chlamys albidus (laminarinase Lo) and Spisula sachalinensis (laminarinase LIV) on Laminaria laminarin have been studied. For laminarinase Lo, the branched products were shown to be 6 2-β- d-glucopyranosyl-laminaribiose and 6 3- and 6 2-β- d-glucopyranosyl-laminaritrioses by methylation analysis and 13C-n.m.r. spectroscopy. It is suggested that one or two (1→3) linkages adjacent to (1→6) branch-points result in resistance to enzymic attack. 6 3-β- d-Glucopyranosyl-laminaritriose inhibited laminarinases Lo and LIV (I 50 1.2 × 10 −3 m and 1.5 × 10 −3 m, respectively).

The surf clam beam trawl fishery and its biological management in Sendai Bay.

Parameters of the Sakhalin surf clam Spisula sachalinensis stock in Sendai Bay were estimated by analyzing the fishery data to examine the management of fishery. The fishing has been greatly influenced by the fluctuation in recruitment, since the age structure has skewed to younger side, The average fishing mortality coefficient F and natural mortality coefficient M during 1980-84 were 0.6358±0.2735, and 0.5323±0, 0915, respectively. The catchability coefficient q was 3.164×10-5. Since the natural mortality coefficient is high, we can expect higher yield per recruit from higher F and lower age of first capture. The most important problem in the management of the stock recruited intermittently by the strong year class, however, is to secure the minimum level of stock which could produce a lat of progeny if the circumstances might become favorable. Since it might be difficult to predict the recruitment from the stock-recruitment relationship, two models were proposed to follow successive stock density. Optimum fishing mortality coefficient is presumed to be between 0.5 and 0.6, which would be able to hold the stock at a level enough to produce recruits under deteriorated conditions.

Non-methylene-interrupted dienoic fatty acids in molluscs from the sea of Japan

Abstract 1. 1. Structural analysis of the fatty acid fraction isolated from lipids of the mollusc Scapharca broughtoni showed that it was the mixture of two isomers non-methylene-interrupted dienoic (NMID) fatty acids Δ7, 13–22:2 and Δ7, 15–22:2 in the ratio 1:1.56. 2. 2. Fatty acid composition of the seven species of marine bivalves and gastropods was studied. 3. 3. The content of NMID fatty acids varied from 0.7% for Spisula sachalinensis to 20.7% for Scapharca broughtoni . The latter value was the highest that is known for molluscs. 4. 4. The regularity of NMID distribution in bivalve molluscs are discussed.

Isolation and some properties of endo-β-1,6-glucanase from marine bivalve Chlamys abbidus

1.1. The testing of carbohydrates, including β-1,3- and β-1,6-glucanases of crystalline styles of two species of the Bivalvia Chlamys abbidus and Spisula sachalinensis has been carried out.2.2. β-1,6-glucanase Po from Chlamys abbidus has been isolated using ion exchange chromatography on SP-Sephadex (C-25, C-50) and gel filtration on Sephadex G-50. Some properties of the isolated enzyme have been studied and the endo-type of action determined.

Accumulation of Co by several species of marine bivalves.

To clarify the effect of chemical form on the accumulation of Co by organisms, a rearing experiment was performed, using 60 Co (CoCl2) as an inorganic compound and 57 Co cyanocobalamin as an organic one. The concentration factor of inorganin 60 Co for Gomphina melanaegis was calculated to be 360 and that of organic 57 Co was 650. The effect of the difference of chemical form was not large in the accumulation of Co by bivalves. The excretion curveof 60 Co consisted of one component, while that of 57 Co by bivalves. The effective half of 60 Co was 31 days and that fo the longer component of 57 Co in the body of G. melanegis was 98 days. A remarkably different distribution of Co was observed in the gills, liver, and kidney, suggesting different metabolism processes dus to the chemical forms in the organs of the bivalves. On the gel filtration profile of Co in the liver of G. melanaegis, inorganic 60 Co was incorporated in two constituents and organic 57 Co was in one compounent. Four species of bivalves G. melanaegis, Tridacna crocea, Spisula sachalinensis and Patinopecten yessoensis showed two peaks of 60 Co in the gel filtration profiles of their livers, while Anadara broughtonii and japonica showed three peaks.

Electrophysiological studies on the responses of the surf clam, Spisula sachalinensis, to the starfish saponins

1. The receptors of the surf clam to starfish saponins were found electrophysiologically to be distributed on the tip of siphons and mantle edge. 2. The siphon nerves responded to inorganic salts and amino acids as well as the saponin. 3. Large neural discharges in response to the saponin and KCl were recorded from connectives while the response to glutamic acid was greatly reduced in the connectives. 4. Information of the saponin and KCl seemed to be transmitted by different fibers of pedal nerve. Any response to glutamic acid was not observed in this nerve.

Enhancement of Spisula sachalinensis by Submerged Dike at Yakumo, Hokkaido

Enhancement of Spisula sachalinensis by Submerged Dike at Yakumo, Hokkaido

On the mechanical fishing of young shells of the surf clam, Spisula sachalinensis

On the mechanical fishing of young shells of the surf clam, Spisula sachalinensis

Purification and some properties of β-1,3-glucan glucanohydrolase from the crystalline style of bivalvia, Spisula sachalinensis

1. 1. β-1,3-Glucan glucanohydrolase, known as laminarinase (EC 3.2.1.6), has been isolated from the crystalline style of Bivalvia, Spisula sachalinensis, by means of gel filtration followed by SE-Sephadex column chromatography. 2. 2. The optimum pH for hydrolysis of laminarin was 5.8. Optimum temperature was 45°. Enzyme was relatively thermostable. The enzyme hydrolyzed laminarin; it was not active towards glucobioses and other sugars. On lengthy hydrolysis laminarin gave rise to glucose and laminaribiose. Mol. wt. 22 000.

The distribution of laminarinases in marine invertebrates

1.1. Fifty species of marine invertebrates of different systematic and ecological positions were tested for quantitative laminarinase activity in their digestive systems.2.2. Laminarinase activity estimated by the increase of reducing sugars in an incubated mixture was found with the majority of the animals studied. The crystalline styles of Bivalvia, such as Spisula sachalinensis and Mactra sulcataria, as well as digestive tracts of some Crustacea, showed the highest enzyme activity.3.3. Laminarinase activity is apparently more dependent upon the systematic position of the invertebrates, though other factors likewise play a notable role.

ウバガイの生殖周期に関する組織学的研究-I

1. Seasonal changes in the ovary of the surf clam, Spisula sachalinensis, collected in Yakumo, southern Hokkaido, were examined histologically. The process of the development of female germ cells was classified into (1) oogonium stage, (2) synaptic stage, (3) early yolkless stage, (4) late yolkless stage, (5) early yolk-formation stage, (6) late yolk-formation stage, and (7) maturation stage. Cytological characteristics of the female germ cells of each stage are described, especially concerning the formation of yolk and chorion in germ cells. 2. On the basis of cytological characteristics of female germ cells and of per cent ratio of oocytes of each stage, maturational processes of the ovaries were classified into (I) spent stage, (2) recovery stage, (3) early growing stage, (4) late growing stage, (5) maturing stage, and (6) spawning stage. 3. In the ovary, germ cells of the oogonium stage and of the synaptic stage are present embedded in the germinal epithelium throughout the year. In early October, oocytes of the yolkless stage begin to appear and grow gradually until December. Yolk formation in the oocytes begins in January, which causes a rapid growth of the ovary during the successive months. The ovary reaches its maximum size mostly in late April, but actual spawning is carried out during the period from late May to early June. The spawning is followed by a period of degeneration and disappearance of the remaining oocytes, which continues for one to two months, and then the ovary enters a period of gradual recovery for the next crop of oocytes. 4. An egg membrane appears at first at the place where the oocytes are protruded from the germinal epithelium, and no membrane can be found at the basal part of the oocyte buried in the germinal epithelium. At the early yolk-formation stage yolk globules make their appearance at first in the cytoplasm of the egg stalk and then are found distributed evenly throughout the whole cytoplasm of the oocyte.

ウバガイの生殖周期に関する組織学的研究-II

1. Seasonal changes in the ovary of the surf clam, Spisula sachalinensis, collected in Yakumo, southern Hokkaido, were examined histologically. The process of the development of female germ cells was classified into (1) oogonium stage, (2) synaptic stage, (3) early yolkless stage, (4) late yolkless stage, (5) early yolk-formation stage, (6) late yolk-formation stage, and (7) maturation stage. Cytological characteristics of the female germ cells of each stage are described, especially concerning the formation of yolk and chorion in germ cells. 2. On the basis of cytological characteristics of female germ cells and of per cent ratio of oocytes of each stage, maturational processes of the ovaries were classified into (I) spent stage, (2) recovery stage, (3) early growing stage, (4) late growing stage, (5) maturing stage, and (6) spawning stage. 3. In the ovary, germ cells of the oogonium stage and of the synaptic stage are present embedded in the germinal epithelium throughout the year. In early October, oocytes of the yolkless stage begin to appear and grow gradually until December. Yolk formation in the oocytes begins in January, which causes a rapid growth of the ovary during the successive months. The ovary reaches its maximum size mostly in late April, but actual spawning is carried out during the period from late May to early June. The spawning is followed by a period of degeneration and disappearance of the remaining oocytes, which continues for one to two months, and then the ovary enters a period of gradual recovery for the next crop of oocytes. 4. An egg membrane appears at first at the place where the oocytes are protruded from the germinal epithelium, and no membrane can be found at the basal part of the oocyte buried in the germinal epithelium. At the early yolk-formation stage yolk globules make their appearance at first in the cytoplasm of the egg stalk and then are found distributed evenly throughout the whole cytoplasm of the oocyte.