Eiji Tanaka

Isolation and characterization of a lethal hemolysin in the sea anemone Parasicyonis actinostoloides

Four species of sea anemones in the coastal waters of Japan were surveyed for hemolysins. Powerful hemolysins were detected in Parasicyonis actinostoloides and Anthopleura japonica, whereas extracts of A. fuscoviridis showed much weaker hemolytic activity and those of of Haliplanella luciae no activity. Among the animal erythrocytes tested sheep were most sensitive to the hemolysins of the three positive species. The major hemolysin (parasitoxin) in whole bodies of P. actinostoloides was isolated by ion exchange chromatography, gel filtration and chromatofocusing. In addition to hemolytic activity (119900 HU/mg) it exhibited lethal activity in mice (LD50 65 micrograms/kg, i.v.) and fish Oryzias latipes (approximate minimum lethal concentration 1.5 micrograms/ml). Parasitoxin was slightly basic (pI 7.9) in nature and its amino acid composition was characterized by the absence of half-cystine. The molecular weight was 19,000 by SDS-polyacrylamide gel electrophoresis or 17,000 by sedimentation equilibrium, indicating that parasitoxin has no subunit structure.

Spatial and temporal migration modeling for stock of Pacific saury Cololabis saira (Brevoort), incorporating effect of sea surface temperature

A model is proposed that expresses the spatial and temporal migration pattern for stock of Pacific saury Cololabis saira (Brevoort), in order to investigate the effect of sea surface temperature (SST) on migration rates. Two factors are considered: (i) Saury emigrate to waters of an optimal SST zone; and (ii) saury immigrate from water zone that is extremely cold for saury. Parameters of migration and initial levels of stock are estimated with a maximum likelihood method based on catch per unit effort (CPUE) data for 1995–2001. The best model was selected using Akaike’s information criteria. The results suggested that the emigration rate to southern adjacent regions is dependent on the coverage proportion of their waters under some threshold temperatures; 20°C to Doutou and Sanriku, 23°C to Joban and Izu.

A two-site sandwich radioimmunoassay of human fibroblast (beta)-interferon with monoclonal antibodies

Monoclonal antibodies were produced against human fibroblast (beta-)interferon (IFN-beta). Four of them were directed to the determinant designated a, while the remaining 3 to another determinant named b. An IFN molecule was found to bear one each of a and b determinants arranged in such a manner that the occupation of a with the corresponding antibody did not interfere with the binding of b to its corresponding antibody, and vice versa. This allowed the development of a 2-site sandwich radioimmunoassay in which antibody to b was immobilized on wells of a microtiter plate and the bound antigen was detected by the radiolabeled antibody to a. The 2-site sandwich radioimmunoassay detected, with a high sensitivity, IFN-beta either induced from fibroblast or produced by Escherichia coli harboring the gene of IFN-beta.

Simultaneous estimation of instantaneous mortality coefficients and rate of effective survivors to number of released fish using multiple sets of tagging experiments

A method is proposed for estimating two instantaneous mortality coefficients, and rate of effective survivors to number of tagged fish released, using exact times at liberty from multiple sets of tagging experiments. Effective survivors are defined here by the product of survivors immediately after releasing and reporting rate of recaptures. A least-squares method was applied to estimate the parameters using statistical models expressing the numbers of effective survivors, which were calculated by a principle similar to virtual population analysis. In order to investigate the statistical performance of the method, simulation trials using operating models were carried out. The method was applied to data of tagging experiments for alfonsino Beryx splendens from 1957 to 1969, off Kanagawa Prefecture. In most of the results of simulation trials, the method yielded estimates of natural mortality coefficient of which expected values were within ±12% of true values. Estimates of natural mortality coefficient, fishing coefficient and the rate of effective survivors for alfonsino are 0.57 (per year, 95% confidence limits [CL] 0.40–0.69), 0.094 (per year, 0.03–0.25) and 0.39 (0.12–1.00), respectively. Modifications for the generalization of the method and notes on its applications are discussed.

Age and growth of yellowstriped butterfish, Labracoglossa argentiventris, around Izu Oshima Island

Age and growth of the yellowstriped butterfish, Labracoglossa argentiventris, around Izu Oshima Island were studied using a total of 1450 fish. Age was determined by counting the edge of the opaque zones as a ring mark on sectioned sagittal otoliths. Formation of the first ring was observed during spring or summer, corresponding to 1.5 years after hatching. Thereafter, one ring was formed each year in the same season as the previous year. The growth of the butterfish was rapid until 2 years of age. The maximum likelihood method was applied to the age and length data for estimating parameters in von Bertalanffy, Gompertz, and Logistic growth models. The selected model, based on the Akaike Information Criterion, was the von Bertalanffy growth model, which indicated differential asymptotic length and variance by sex.

Study for coastal fisheries stock management. I. Selection of target species and operating areas for coastal trawlers.

The data used in this paper are catch statistics of coastal trawl fishery in the Sea of Japan off Niigata Prefecture in 1983. The relative fishing power of 15 groups of boats, stratified by the base ports and classes of power of engines, were estimated for each of 4 flatfishes and others by a simple method to compare CPUEs in the same fishing area in the same month from the pair data. The standardized CPUE in each area was calculated. Allocation pattern of fishing power to each species is different among groups and they are separated into three clusters by the cluster analysis. These clusters agreed with similarity among boats in the species composition of catch. The allocation patterns of relative fishing power are related to the stock abundance in their operating areas. Problems in applying the management measures are discussed. The advantages of existence of several clusters for the stock management are: (1) to aviod concentration of effort on a specified stock; (2) to mitigate the competition among fishermen. However, the benefit from a stock management measure would often not be equal among fishermen and this is the disadvantages of the existence of clusters.