Mortality processes of hatchery‐reared Pacific bluefin tuna Thunnus orientalis (Temminck et Schlegel) larvae in relation to their piscivory          下载免费PDF全文

Yosuke Tanaka  Kazunori Kumon  Yuka Ishihi  Takeshi Eba  Akefumi Nishi  Hideki Nikaido  Satoshi Shiozawa 《Aquaculture Research》2018,49(1):11-18

In mass culture of Pacific bluefin tuna Thunnus orientalis, yolk‐sac larvae of other species are fed as a major prey item to tuna larvae from 7 to 8 mm in total length. Marked growth variations in tuna larvae are frequently observed after feeding of yolk‐sac larvae, and this variation in the growth of tuna larvae is subsequently a factor leading to the prevalence of cannibalistic attacks. To elucidate details of the mortality process of hatchery‐reared tuna larvae after the initiation of yolk‐sac larvae feeding, we compared the nutritional and growth histories of the surviving (live) tuna larvae to those of the dead fish, found dead on the bottom of the tank, as direct evidence of their mortality processes. Cause of mortality of tuna larvae 3 and 5 days after the initiation of feeding of yolk‐sac larvae was assessed from nitrogen stable isotope and otolith microstructure analyses. Stable isotope analysis revealed that the live fish rapidly utilized prey fish larvae, but the dead fish had depended more on rotifers relative to the live fish 3 and 5 days after the initiation of feeding of yolk‐sac larvae. The growth histories based on otolith increments were compared between the live and dead tuna larvae and indicated that the live fish showed significantly faster growth histories than dead fish. Our results suggest that fast‐growing larvae at the onset of piscivory could survive in the mass culture tank of Pacific bluefin tuna and were characterized by growth‐selective mortality.  相似文献   

Factors Influencing Early Survival and Growth of Laboratory‐reared Pacific Bluefin Tuna,Thunnus orientalis,Larvae          下载免费PDF全文

Yosuke Tanaka  Kazunori Kumon  Kentaro Higuchi  Takeshi Eba  Akefumi Nishi  Hideki Nikaido  Satoshi Shiozawa 《Journal of the World Aquaculture Society》2018,49(3):484-492

The collection of fertilized eggs for mass culture of Pacific bluefin tuna (PBT) relies on the spontaneous spawning of broodstock in captivity, and the spawning season of the broodstock is generally from mid‐May to September. The diameter of fertilized eggs from the broodstock decreases during the spawning season. To investigate the influence of three potential factors, the egg diameter (larger or smaller), the rearing water temperature (25 or 28 C), and the aeration rate during the night (strong or weak), on early survival and on growth of PBT larvae, replicate trials were conducted to assess these three factors until 7 d after hatching (d.a.h.). At 7 d.a.h., survival rates of larvae reared with strong nighttime aeration were found by a three‐way ANOVA to be significantly higher than for larvae reared with weak aeration. Furthermore, growth rates of PBT larvae hatched from larger eggs were significantly faster than those from smaller eggs. However, a significant difference in the survival rate was not detected for the factors, egg diameter and rearing water temperature. The results indicate that rearing with strong nighttime aeration significantly improved the early survival of PBT larvae and the egg diameter (a proxy for egg quality) and influenced growth.  相似文献   

Genomic evaluation using SNP‐ and haplotype‐based genomic relationship matrices in a closed line of Duroc pigs          下载免费PDF全文

Yoshinobu Uemoto  Shuji Sato  Takashi Kikuchi  Sachiko Egawa  Kimiko Kohira  Hironori Sakuma  Satoshi Miyashita  Shinji Arata  Takatoshi Kojima  Keiichi Suzuki 《Animal Science Journal》2017,88(10):1465-1474

A simulation analysis and real phenotype analysis were performed to evaluate the impact of three different relationship matrices on heritability estimation and prediction accuracy in a closed‐line breeding of Duroc pigs. The numerator relationship matrix (NRM), single nucleotide polymorphism (SNP)‐based genomic relationship matrix (GRM) (G_S), and haplotype‐based GRM (G_H) were applied in this study. We used PorcineSNP60 genotype array data (38 114 SNPs) of 831 Duroc pigs with four selection traits. In both heritability estimation and prediction accuracy, the accuracy depended on the number of animals with records. For heritability estimation, a large difference in the results among three relationship matrices was not shown, but the trend of the estimated heritabilities between GRMs, that is G_S < G_H, was shown in this population. For the accuracy of prediction values in test animals, the accuracies of prediction values obtained by two GRMs were higher than that by the NRM in this population. The accuracies obtained by GRMs using animals with no records were lower than that by the NRM using animals with their performance records, but were close to that by the NRM using animals with full‐sib testing records.  相似文献   

Changes in the morphology and functions of vacuoles during the death of ray parenchyma cells in <Emphasis Type="Italic">Cryptomeria japonica</Emphasis>     

Izumi Arakawa  Ryo Funada  Satoshi Nakaba 《Journal of Wood Science》2018,64(3):177-185

Changes in the morphology and functions of vacuoles provide useful information about the mechanism of cell death. In the present study, we monitored the morphology and contents of vacuoles during the death of ray parenchyma cells in the conifer Cryptomeria japonica. In differentiating xylem, ray parenchyma cells had large central vacuoles. In sapwood, vacuoles in ray parenchyma cells contained proteins, an indication that one of the main functions of these vacuoles might be protein storage. A dramatic decrease in the protein content of some vacuoles was detected in the intermediate wood before the initiation of vacuole rupture. Although vacuole rupture was detected from the intermediate wood to the outermost heartwood, some vacuoles were obviously enlarged in the inner intermediate wood. Condensed nuclei were first observed after the rupture of these large vacuoles in ray parenchyma cells. It seems plausible that the autolysis of the contents of ray parenchyma cells might be caused by the rupture of the enlarged vacuoles in the inner intermediate wood.  相似文献   

Weeds as the potential inoculum source of <Emphasis Type="Italic">Colletotrichum fructicola</Emphasis> responsible for strawberry anthracnose in Nara,Japan     

Yoshihiko Hirayama  Shunsuke Asano  Ken’o Okayama  Satoshi T. Ohki  Motoaki Tojo 《Journal of General Plant Pathology》2018,84(1):12-19

Colletotrichum fructicola is a major causal agent among anthracnose pathogens of strawberry in Nara, Japan. We hypothesized that a wide range of weeds growing in and around strawberry fields are inoculum sources of the disease and investigated their potential as hosts of C. fructicola. We also examined the influence of herbicide treatment on C. fructicola sporulation on weeds. The fungus was detected on 31 of 541 (5.7%) leaves sampled from 13 weed species from 2005 to 2008. The fungus was most frequently isolated from leaves of Amaranthus blitum with an isolation frequency of 17.9%; inoculation of A. blitum with the pathogen caused brown leaf spots. Other weeds such as Digitaria ciliaris, Galinsoga ciliata, Solidago altissima, Erigeron annuus, and Sonchus oleraceus were found to harbor the fungus at lower rates (4.3–8.1%) without symptoms. C. fructicola formed acervuli on leaves of A. blitum, D. ciliaris, and S. oleraceus after plants were killed by a herbicide (glyphosate). These results demonstrated that infected weeds associated with strawberry cultivation are potential inoculum sources of C. fructicola, especially after herbicide treatment.  相似文献   

The genetic variability and population structure of the marbled rockfish Sebastiscus marmoratus in western Japan,as inferred by microsatellite DNA markers     

Tomano  Satoshi  Yasuhara  Shota  Takagi  Motohiro  Umino  Tetsuya 《Fisheries Science》2019,85(6):961-970

Fisheries Science - Identification of the population structure of harvested species is the first step in the management of wild fisheries. Although the marbled rockfish Sebastiscus marmoratus is a...  相似文献   

Validation of daily increment formation in otoliths of immature and adult Japanese anchovy <Emphasis Type="Italic">Engraulis japonicus</Emphasis>     

Shigenobu Namiki  Hiroshige Tanaka  Satoshi Katayama  Osamu Funaki  Ichiro Aoki  Yoshioki Oozeki 《Fisheries Science》2010,76(6):951-959

In order to validate daily increment formation in otoliths of immature and adult Japanese anchovy Engraulis japonicus, three rearing experiments using chemical marking of otoliths were conducted on adult anchovy in summer 2004 and immature anchovy in summer 2005 and in winter 2006. In the two experiments conducted in summer, the number of otolith microincrements between alizarin complexone (ALC) marks showed that microincrements were formed daily. In the summer 2005 experiment, immature anchovy under conditions of reduced daily food rations also showed daily microincrement formation. Average increment width was 0.9 μm in adults and 1.8–3.1 μm in immature anchovy. In contrast, no clear increments were observed between ALC marks on the otoliths from the experiment in winter 2006, and scanning electron microscope (SEM) observations failed to confirm clear increment formation. We consider that low water temperatures (<13–14°C) restricted otolith growth and lowered the contrast between the discontinuous and the incremental zones of the otolith increments. For age estimation of Japanese anchovy, clear increments wider than about 1 μm in the otolith can be regarded as daily increments. However, daily age estimation of immature and adult anchovy that experience low water temperatures in winter may be difficult due to the obscurity of the increments.  相似文献   

In situ growth and mortality of juvenile Acropora over 2 years following mass spawning in Sekisei Lagoon,Okinawa (24°N)     

Okamoto  Mineo  Yap  Minlee  Roeroe  Andreus Kakaskasen  Nojima  Satoshi  Oyamada  Kumi  Fujiwara  Shuichi  Iwata  Itaru 《Fisheries Science》2010,76(2):343-353

The growth of Acropora in Sekisei Lagoon was investigated in situ using ceramic coral settlement devices (CSDs) and marine blocks (MBs) with small holes on their surfaces that were deployed prior to a mass spawning event. Acropora that had settled in 10-mm holes on the upper surface of the MBs were found to have grown inwards after 348 days post-mass spawning. After 733 days, the colonies had grown outwards, encrusting the blocks and attaining a maximum diameter of 21.5 mm (3.7 mm). CSDs that had been stacked above each other on frames were separated and observed in situ on 405 and 764 days after mass spawning. After 405 days, the maximum diameter of the encrusting Acropora was 7.6 mm (±2.4 mm), which increased to 19.4 mm (±5.5 mm) after 764 days, with 30% of colonies extending short branches. The length of the branches of Acropora grown on the CSDs fixed to the MBs 3 months after the mass spawning event exceeded the size of the encrusting portion of the colony 629 days after spawning. The mortality of colonies between 1 and 2 years was slight, with the temperatures conducive to coral bleaching that occurred during the study also having only a slight effect.  相似文献   

Seasonal changes in otolith and somatic growth in age-0 Pacific saury <Emphasis Type="Italic">Cololabis saira</Emphasis>     

Satoshi Suyama  Kazuhiro Oshima  Masayasu Nakagami  Atsushi Kawabata 《Fisheries Science》2011,77(2):223-233

We evaluated the seasonal changes in otolith and somatic growth of age-0 Pacific saury Cololabis saira in 223 fish collected between June and November 2002. We calculated the age in days of each individual by measuring otolith growth increments under a scanning electron microscope. The age was correlated with body length and otolith radius. We also observed seasonal changes in the rate of increase in body length and otolith radius and in the pattern of otolith growth. Until August, both body length and otolith radius increased with age. Thereafter, the otolith radius continued to increase, whereas the rate of somatic growth decreased. As a result, the ratio of otolith radius to body length increased. After August, the percentage of otoliths with unreadable increments on their edge increased due to the formation of hyaline zones. Otoliths grew both radially and in thickness until July, but gradually stopped growing in thickness after August. Beginning in October, more than 80% of otoliths only grew radially. After August, the otolith not only continued growing but the morphological growth pattern also changed.  相似文献   

Expression of podoplanin in various types of feline tumor tissues     

Satoshi KAMOTO  Masahiro SHINADA  Daiki KATO  Masaya TSUBOI  Sho YOSHIMOTO  Ryohei YOSHITAKE  Shotaro ETO  Namiko IKEDA  Yosuke TAKAHASHI  Yuko HASHIMOTO  James CHAMBERS  Kazuyuki UCHIDA  Shinji YAMADA  Mika K. KANEKO  Ryohei NISHIMURA  Yukinari KATO  Takayuki NAKAGAWA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2021,83(11):1795

Podoplanin is expressed in various human tumors where it promotes tumor progression, epithelial-mesenchymal transition, and distant metastasis. Podoplanin is also expressed in cancer-associated fibroblasts and induces tumor malignancy. The objective of this study was to evaluate podoplanin expression in various types of feline tumor tissues. Immunohistochemical analysis revealed that podoplanin was expressed in cells of 13/15 (87%) squamous cell carcinomas and 5/19 (26%) fibrosarcomas. Moreover, cancer-associated fibroblasts expressed podoplanin in most tumor types, including 18/21 (86%) mammary adenocarcinoma tissues. Our findings demonstrate that various types of feline tumor tissues expressed podoplanin, indicating the importance of the comparative aspects of podoplanin expression, which may be used as a novel research model for podoplanin biology.  相似文献