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Basic research for automatic construction of course timetables in National Fisheries University
Get PDFSince the construction of class timetables in the university requires a great deal of effort and time, many studies have been conducted in Japan and abroad on the automatic construction of class timetables. Similarly, at the National Fisheries University, labor and time are devoted to the creation of class timetables. Therefore, author aims to conduct basic research on automatic timetable construction with the simulated annealing method in this study. This paper describes the proposed method and algorithm for generating timetables using the simulated annealing method. The generated timetables by the proposed method are also reported.編集：水産大学校departmental bulletin pape
Development of the eosinophilic granules in the eosinophils from larva (ammocoetes) of far eastern brook lamprey Lethenteron reissneri
Get PDFStructure and development of eosinophilic granules (EG1) in eosinophils from larva (ammocoetes) of far eastern brook lamprey Lethenteron reissneri were speculated. EG1 is stratified granules (two-layer) and consists of inner eosinophilic layer (L0) and chromophobic outer layer (L1). Three subtypes of EG1 are identified based on the optical artificial image (OAI) of inclusion structure (IS) in L0: EG1a, EG1b, and EG1c. The EG1a had no OAI (probably no IS). The EG1b and EG1c contain IS in L0. The OAI of both EG1b and EG1c were larger than IS. The former was round or oval chromophobic area (OAI-1), and the latter was expanded and rugged (three-dimensional) image (OAI-2) surrounded with OAI-1. EG1a was thought to be a prototype of EG1, which would develop into EG1b and then EG1c.編集：水産大学校departmental bulletin pape
A case of paralytic shellfish poisoning caused by consumption of visceral balls from geoduck Panopea japonica in Japan
Get PDFIn the end of March 2018, an unprecedented food poisoning incident due to ingestion of the visceral balls of geoduck Panopea japonica occurred in Japan. The patient, presented with symptoms of numbness on the lips and general weakness, was diagnosed as paralytic shellfish poisoning (PSP). The patient immediately treated with the mechanical ventilation recovered and left the hospital after 3 days treatment. Saxitoxins (STXs) in the plasma and urinary samples collected from the patient on the first and second day after hospitalization were analyzed by ultra high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC/MS/MS) and liquid chromatography with post-column fluorescent detection (LC/FLD). The STXs levels of 499.1 and 6.0 μg/L of STX dihydrochloride equivalent (STX·2HCl eq.) were quantitated by LC/FLD in the urinary samples on the first and second day, respectively. In addition, geoducks harvested from the same areas of the PSP causative specimens after the incident were analyzed by LC/FLD, and the results showed the level of STXs in their whole bodies of the geoducks exceeding 0.8 mg STX·2HCl eq./kg which is the maximum levels of STX in CODEX STAN 292–2008. Prominent toxins in STXs that detected in urinary and geoduck samples and identified by UHPLC/MS/MS and LC/FLD were gonyautoxin-1+4 (GTX1+4). These results concluded that the incident was the food poisoning due to STXs accumulated in the geoducks. This is the first PSP case caused by consumption of geoducks in Japan. This is also the first PSP case that causative toxins are detected in urinary samples of patients involved in PSP in Japan.journal articl
New records of a freshwater fish parasite Argulus japonicus (Branchiura: Argulidae) from northern Honshu, Japan, with a note on its occurrence in a brackish water lake
Get PDFOne and two specimens of Argulus japonicus Thiele, 1900 were collected from the body surface of big-scaled redfin Pseudaspius hakonensis (Günther, 1877) (Cypriniformes: Leuciscidae) in the Babame River, Akita Prefecture, and Lake Jusan, Aomori Prefecture, northern Honshu, Japan, respectively. This is two new prefecture records in Japan and a new host record for A. japonicus. Lake Jusan is the northernmost collection locality of this parasite in Japan recorded from wild fishes. As Lake Jusan is a brackish water lake and big-scaled redfin is known to migrate from fresh to salt waters, and since A. japonicus completes its life cycle in fresh waters, we infer that the two individuals of A. japonicus parasitized the big-scaled redfin in an inflowing river, then this fish was collected along with the surviving argulid individuals after migrating to the lake. The collection of A. japonicus in Lake Jusan represents the second record for the species from brackish water lakes in Japan.journal articl
Estimation of optimum temperatures for terrestrial hermit crabs in the zoeal stage using the thermodynamic Sharpe–Schoolfield–Ikemoto model
Get PDFThe intrinsic optimum temperatures (TΦ) for the zoeal stages of five species of the terrestrial hermit crab genera Birgus and Coenobita, namely B. latro, C. brevimanus, C. purpureus, C. rugosus, and C. violascens, were estimated based on the relationship between temperature and the number of developmental days using the nonlinear thermodynamic Sharpe–Schoolfield–Ikemoto model. The results showed that the TΦ estimates (approximately 26 °C) corresponded to the temperatures at which high survival rates were observed for the zoeae, except for C. rugosus, whose TΦ was approximately 24 °C. The low TΦ of C. rugosus when compared to the other species may have been due to the relatively high northern latitude of its distribution and its late breeding season. The optimum temperatures determined for these terrestrial hermit crabs would be useful in understanding and predicting the changes in and northward expansion of their distributions.journal articl
Characterization of eight types of 17β-hydroxysteroid dehydrogenases from the Japanese sardine Sardinops melanostictus: The probable role of type 12a in ovarian estradiol synthesis
Get PDF17β-hydroxysteroid dehydrogenases (Hsd17bs) play a critical role in sex steroid biosynthesis. Although multiple types of Hsd17b have been found in fish, there is limited research on their expression and function. Recently, we succeeded in identifying eight types of Hsd17b (types 3, 4, 7, 8, 10, 12a, 12b, and 14) by RNA sequencing in the Japanese sardine Sardinops melanostictus, a commercially important clupeoid fish; however, a homologous sequence of Hsd17b1, which catalyzes the key reaction of estradiol-17β (E2) synthesis, was absent. Here, we aimed to identify the Hsd17b type that plays a major role in E2 synthesis during ovarian development in Japanese sardine. The cDNAs encoding those eight types of Hsd17b were cloned and sequenced. The expressions of hsd17b3, hsd17b12a, and hsd17b12b were higher in ovary than in testis. In particular, hsd17b12a was predominantly expressed in the ovary. Expression of hsd17b3, hsd17b4, hsd17b12a, and hsd17b12b in the ovary increased during ovarian development. The enzymatic activities of Hsd17b3, Hsd17b12a, and Hsd17b12b were evaluated by expressing their recombinants in human embryonic kidney 293T cells. Hsd17b12a and Hsd17b12b catalyzed the conversion of androstenedione (AD) to testosterone (T) and estrone (E1) to E2. The results of in vitro bioassays using sardine ovaries indicated that E2 is synthesized from pregnenolone via AD and T, but not E1. These results suggest that Hsd17b12a plays a major role in E2 synthesis in sardine ovary by catalyzing the conversion of AD to T.journal articl
Changes in Behavior and Diel Melatonin Secretion Toward Estivation in Western Sand Lance, Ammodytes Japonicus (Uranoscopiformes, Ammodytidae)
Get PDFWestern sand lance, Ammodytes japonicus, is known to have an estivation period, in which they cease feeding and stay in the sand from early summer to late autumn, followed by gonadal maturation. During the feeding period prior to estivation, they swim in daytime and spend the night in the sand. Before they start swimming, they show a typical behavior of head-exposing from the sand, which is likely to be related to foraging and predation avoidance. Our previous study revealed that melatonin regulates such diel behavior of this species. To elucidate the mechanisms of behavioral regulation throughout the life cycle of this sand lance, the present study examined the changes in behavior and melatonin secretion toward the estivation period. Both head-exposing and swimming behaviors were frequently observed at the transition period toward estivation. On the other hand, occurrence of these behaviors was suppressed just before entering estivation. Subsequently, it was found that plasma melatonin concentration was about three times higher at night than in daytime in the non-estivation period, while it was retained at high levels throughout the day in the estivation period. These results indicate that diurnal swimming behavior of sand lance from the feeding to estivation periods is associated with the daily cycle of melatonin secretion.journal articl
Idea and basic research on the dead fish collection system using underwater robot in medium to large fish aquaculture
Get PDFIn aquaculture, leaving dead fish that have sunk to the bottom of the net for a long time causes harmful components from the dead fish body. This risk making other fish in the aquaculture net sick. The early collection of dead fishes is required, but when divers work in the sea, high water pressure and low water temperatures make it difficult for them to work for a long time, and the work efficiency of the entire aquaculture facility is reduced due to the need for manpower.
To protect aquaculture fishes from disease, it is useful to install devices and robots to detect and collect the dead fish at an early stage. If the target is small fishes, there is a pumping method. But if the target is medium to large fishes, it is not reasonable. Therefore, we devised a system for collecting dead fishes using AUV(autonomous underwater vehicle) and wire. This report describes the configuration and operation of this system, and conducts simple experiments to confirm its feasibility.編集：水産大学校departmental bulletin pape
Growth–feeding linkage in small pelagic fish larvae in the Kii Channel, Japan
Get PDFThe linkage between growth rate and feeding success has been shown to strengthen the effects of early growth rate on later growth rate in the early life history of fish. However, the growth–feeding linkage largely remains to be tested at the individual level within the same populations/cohorts. We examined the growth–feeding linkage for multiple populations/cohorts in Japanese anchovy
Engraulis japonicus larvae and Pacific round herring Etrumeus micropus larvae, through otolith microstructure analysis, based on samples collected from the commercial fishery for larval fish in the Kii Channel, Japan. The three growth–feeding mechanisms, which are based on the respective potential advantages of larger somatic size, higher growth rate, and earlier morphological development for achieving feeding success, were tested to understand how growth rate relates to feeding success. The “somatic size” mechanism was supported for all of six samples for anchovy larvae and three of four samples for round herring larvae. The “growth rate” mechanism was supported for two of six samples for anchovy larvae and three of four samples for round herring larvae. The “morphological development” mechanism was supported for three of four samples for anchovy larvae and all of three samples for round herring larvae. Overall, the present analysis supported the growth–feeding linkage but revealed the dynamics of the growth–feeding mechanisms. All the mechanisms were shown to operate at least for certain populations/cohorts, but none of them were universally effective over all populations/cohorts across the two species. Understanding the dynamics of the growth–feeding mechanisms would provide precious hints for considering strategies of predicting recruitment dynamics.journal articl