Requiem Shark Research Articles

Proximate and protein compositions of requiem shark muscle.

Proximate and Protein compositions of the ordinary muscle of requiem shark Triakis scyllia were examined. The proximate composition of the dorsal muscle was: moisture 76.0%, crude protein 24.9%, crude fat 2.7%, and crude ash 1.3%, The proein content corrected for urea (5.4mgN/g) and for non-protein nitrogenous compounds (11.2mgN/g) was 21.5% and 17.5%, respectively. The protein compositions of the dorsal and ventral muscle remained unchanged essentially through pre-, in-, and post-rigor stages: In the dorsal part, sarcoplasmic 22.1-25.9% (av. 24.5%), myofibrillar 60.1-66.8% (63.2%), alkail-soluble 4.1-5.5% (4.7%), and stroma fraction 6.5-8.9% (7.6%). In the ventral part, corresponding data were 20.4-26.1% (24.2%), 58.4-67.2% (63.5%), 2.9-9.2% (6.1%), and 3.8-8.2% (6.1%), respectively. The protein composition of each muscle did not show any significant changes after a 2-week frozen storage at -20°C.

Identification of 5,5'-dithio-bis-2-nitrobenzoic acid (DTNB) and alkali light chains of piscine myosin.

Myosins were prepared from the ordinary muscles of 14 species of fish, and analyzed for light chain subunits by SDS-gel electrophoresis. DTNB light chain and two alkali light chains A1 and A2, in the order of increasing mobility, were dissociated from the myosin of each fish. Molecular weights of the myosin subunits were determined to be in the ranges 17, 500-21, 000 for DTNB light chains, 25, 000-30, 000 for A1 and 13, 500 for A2 light chinas, respectively. In each scombroid fish tested, the molecular weight of A2 was clearly than that of DTNB light chain; the opposite result was found in several othere fishes including carp and pufferfish. In the group of fishes such as sardine and horse mackerel, both light chains showed the same the same molecular weight. These results suggested that there is some correlation between the molecular weight of A2 and the locomotory activity of fish. Quantitaive analysis showed that piscine myosins contained approximately two moles each of DTNB and of alkali light chains per mole. However, the rations of A1/A2 differed widely, form 0.1 (grunt) to 2.6 (requiem shark).

養殖ハマチに寄生する嚢虫に関する研究-XI

Studies were made on the growth of adult Callotetrarhynchus sp. in the valvular intestine of Triakis scyllia, a kind of requiem shark, which was demonstrated by a previous study to be a suitable experimental final host for this cestode. Parasitefree sharks were prepared by raising juveniles at the Himeji City Aquarium. Twenty bladder worms collected from the body cavity of Seriola quinqueradiata were introduced into each shark by a catheter into the stomach. The sharks examined for the number of adults and for the growth of the cestode from 2 to 80 days after administration. From the experiment the following conolusions were reached: 1) The adult of Callotetrarhynchus sp. was thought to be harmful to the host. Of the 35 sharks, 12 died during the course of the experiment. The dying animals always showed an abnormal movement a few days before death and severe intestinal inflammation was observed in all the dying or dead sharks. 2) The adult stage, which could continue to grow without killing the host, was limited in number. The number of adults varied with the size of the valvular intestine and with the growth of the adult. 3) In the valvular intestines of normal sharks, the post-holdfast zone of the adult parasite stretched rapidly and then segmentation started. Adults matured in about 15 days after administration at temperatures of 21.8-26.5°C. At the same time, free proglottides were found to be separated from the strobilae. All gravid proglottides moved to the outside through the anus within 40 days. Most of the adults died in the valvular intestine after about 25 days and were discharged one by one.