Oocyte maturation and active motility of spermatozoa are triggered by retinoic acid in pen shell <Emphasis Type="Italic">Atrina pectinata</Emphasis>     

Masahiko Awaji  Toshie Matsumoto  Daisuke Ojima  Shunsuke Inoue  Michio Suzuki  Masaei Kanematsu 《Fisheries Science》2018,84(3):535-551

For recovery of the declining population of pen shells in the wild, the production of pen shell juveniles for transplantation or aquaculture is underway in Japan. For more stable juvenile production, artificial fertilization methods for pen shells are needed, but methods to induce oocyte maturation (meiosis resumption) used in other bivalves, which make oocytes fertilizable, were ineffective for pen shells. Here, we report evidence showing that retinoic acid (RA) has strong activity in inducing oocyte maturation and activating sperm motility in pen shells. Treatment of fully developed oocytes with 1.0 μM all-trans-RA (at-RA) induced germinal vesicle breakdown, a typical morphological sign of oocyte maturation, but 1.0 μM at-retinol and at-retinal, 2 mM ammonia, and 1.0 μM serotonin were ineffective. Treatment with at-RA for 30 min was sufficient for oocyte maturation and was more potent than its isomers, 9-cis- and 13-cis-RA. Parallel results were obtained for sperm motility activation. Oocyte responsiveness to at-RA increased during the final stage of ovary development. Artificial fertilization was successful only with the oocytes treated with at-RA, and fertilized eggs developed to D-shaped (veliger) larvae without apparent morphological abnormalities. These results indicate the possible application of RA for the artificial fertilization of pen shells.  相似文献   

Changes in above- and belowground biomass in early successional tropical secondary forests after shifting cultivation in Sarawak,Malaysia     

Tanaka Kenzo  Tomoaki Ichie  Daisuke Hattori  Joseph Jawa Kendawang  Katsutoshi Sakurai  Ikuo Ninomiya 《Forest Ecology and Management》2010

Uncertainties in the rate of biomass variation with forest ageing in tropical secondary forests, particularly in belowground components, limit the accuracy of carbon pool estimates in tropical regions. We monitored changes in above- and belowground biomass, leaf area index (LAI), and biomass allocation to the leaf component to determine the variation in carbon accumulation rate with forest age after shifting cultivation in Sarawak, Malaysia. Nine plots in a 4-year-old forest and fourteen plots in a 10-year-old forest were monitored for 5 and 7 years, respectively. Forest and plant part biomass were calculated from an allometric equation obtained from the same forest stands. Both above- and belowground biomass increased rapidly during the initial decade after abandonment. In contrast, a much slower rate of biomass accumulation was observed after the initial decade. LAI also increased by approximately double from the 4-year-old to 10-year-old forest, and then gently increased to the 17-year-old forest. We also found that allocation variation in leaf biomass and nitrogen was closely related to the rate of biomass accumulation as a forest aged. During the first decade after abandonment, a high biomass and nitrogen allocation to the leaf component may have allowed for a high rate of biomass accumulation. However, reduction in those allocations to leaf component after the initial decade may have helped to suppress the biomass accumulation rate in older secondary forests. Roots accounted for 14.0–16.1% of total biomass in the 4–17-year-old abandoned secondary forests. We also verified the model predicted values for belowground biomass by Cairns et al. (1997) and Mokany et al. (2006), although both models overestimated the values throughout our data sets by 45–50% in the 10-year-old forest. The low root:shoot ratio in the secondary forests may have caused this overestimation. Therefore, our results suggest that we should modify the models to estimate belowground biomass considering the low root:shoot ratio in tropical secondary forests.  相似文献   

Isotopic trophic-step fractionation of the freshwater clam <Emphasis Type="Italic">Corbicula sandai</Emphasis>     

Akihide Kasai  Daisuke Ishizaki  Takane Isoda 《Fisheries Science》2016,82(3):491-498

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Changes in plasma steroid levels and gene expression of pituitary gonadotropins,testicular steroidogenesis-related proteins and insulin-like growth factors during spermatogenesis of the yellowtail <Emphasis Type="Italic">Seriola quinqueradiata</Emphasis>     

Kentaro Higuchi  Koichiro Gen  Daisuke Izumida  Yukinori Kazeto  Takuro Hotta  Toshinori Takashi  Hideaki Aono  Kiyoshi Soyano 《Fisheries Science》2017,83(1):35-46

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Transcriptome analysis of tetrodotoxin sensing and tetrodotoxin action in the central nervous system of tiger puffer <Emphasis Type="Italic">Takifugu rubripes</Emphasis> juveniles     

Kogen Okita  Engkong Tan  Hina Satone  Shigeharu Kinoshita  Shuichi Asakawa  Daisuke Ojima  Hideki Yamazaki  Kazutaka Sakiyama  Tomohiro Takatani  Osamu Arakawa  Atsushi Hagiwara  Yoshitaka Sakakura 《Fisheries Science》2017,83(3):401-412

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Reproduction affects partitioning between new organs of a pulse of 15N applied during seed ripening in Fagus crenata     

Han  Qingmin  Kabeya  Daisuke  Inagaki  Yoshiyuki 《New Forests》2020,51(5):739-752

Seasonal internal nitrogen (N) cycling is an important strategy for trees to uncouple growth from N acquisition. While N uptake, allocation and storage has been intensively studied in association with leaf phenology and vegetative growth, influence of reproduction on these key processes is still poorly understood. Therefore, we applied pulse ¹⁵N labelling to three fruiting and three non-fruiting trees in a 92-year-old Fagus crenata forest on 18 July and traced ¹⁵N content per organ dry mass (¹⁵N_excess) in all new shoot organs from the upper crowns periodically until leaf fall. The amount of ¹⁵N_excess recovered in the whole new shoots in fruiting trees did not differ from non-fruiting individuals, although up to 70% of ¹⁵N_excess was recovered in fruits of fruiting trees but 87% in leaves of non-fruiting individuals. In addition, dramatic increase in ¹⁵N_excess amount in nuts was accompanied by about twofold increase in nut N content. These results indicate that new N uptake from the soil contributed greatly to seed ripening, which in turn resulted in less allocation to leaves in fruiting trees. In non-fruiting individuals, on the other hand, ¹⁵N_excess allocated to leaves was not accompanied by concomitant increase in leaf N content because biomass growth had ceased when ¹⁵N was applied. These results suggest that N uptake in the late growing season contributed to internal N storage in non-fruiting trees. These reproduction-related variations in seasonal N cycle have implications for N dynamics in the plant–soil system during environmental change.

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Synthesis and antifungal activity of the proposed structure of a volatile compound isolated from the edible mushroom Hypsizygus marmoreus     

Nguyen Thi Ngoc Anh  Daisuke Miyaji  Kumiko Osaki-Oka  Tatsuo Saito  Atsushi Ishihara  Arata Yajima 《Journal of Pesticide Science》2022,47(1):17

We synthesized the proposed structure of an antifungal compound detected in the culture broth of the edible mushroom Hypsizygus marmoreus. Using the Evans aldol and Abiko–Masamune aldol reactions as the key steps, we synthesized all of the stereoisomers of the compound with high stereoselectivity. The GC retention times and the fragmentation patterns in the mass spectra of the synthesized isomers did not match those of the natural product. Therefore, this result may imply that it is necessary to reisolate the natural product and reconsider its structure. All of the synthesized isomers were found to exhibit antifungal activity against the phytopathogenic fungus Alternaria brassicicola. Due to their simple structures, the obtained isomers could be lead compounds for new pesticides.  相似文献   

Effect of thin twine on gill net size-selectivity analyzed with the direct estimation method     

Kosuke Yokota  Yasuzumi Fujimori  Daisuke Shiode  Tadashi Tokai 《Fisheries Science》2001,67(5):851-856

ABSTRACT: To analyze the effect of thin twine on gill net size selectivity, a series of fishing experiments using gill nets of two twine thicknesses (no. 0.8 of 0.16 mm diameter and no. 3 of 0.28 mm diameter) and three nominal mesh sizes (41 mm, 46 mm and 51 mm) was conducted in outdoor water tanks containing a rainbow trout ( Oncorhynchus mykiss ) population of known size frequency. For nets of the same nominal mesh size, mesh openings of the no. 0.8 twine nets were approximately 2 mm larger than those of the no. 3 twine nets. The effects of both mesh opening and twine thickness are combined in the conventional analysis with the selectivity curve against fish length. Selectivity against the ratio of fish girth to mesh perimeter was calculated to avoid the direct effect of changes in mesh openings due to twine diameter at the same nominal mesh size. Results demonstrated that the thinner twine gill net was more likely to capture rainbow trout of smaller girth than the mesh perimeter. Fish with girths smaller than the mesh perimeter were often retained by the net with its body tangled by the thinner twine, possibly due to the increased flexibility of the thinner twine.  相似文献   

Genome sequencing and functional genomics approaches in tomato   总被引：5，自引：0，他引：5  

Daisuke Shibata 《Journal of General Plant Pathology》2005,71(1):1-7

Tomato genome sequencing has been taking place through an international, 10-year initiative entitled the International Solanaceae Genome Project (SOL). The strategy proposed by the SOL consortium is to sequence the approximately 220Mb of euchromatin that contains the majority of genes, rather than the entire tomato genome. Tomato and other Solanaceae plants have unique developmental aspects, such as the formation of fleshy fruit, not afforded by Arabidopsis or rice. Divergent phenotypes and habitats of the Solanaceae also make the family an ideal model to explore the bases of diversification and adaptation. Current progress in genome sequencing, genetic and genomic resources, and functional genomics approaches for tomato is summarized. Given the foreseen wealth of information in the upcoming genome sequence, the role of the laboratory-grown miniature tomato cultivar Micro-Tom as a valuable functional genomics tool for plant pathology and emerging areas of biology, such as omics biology, is emphasized.  相似文献   

Tissue retention and adverse reaction after intravenous injection of hematoporphyrin derivatives in dogs     

Okamoto Y  Yonemura D  Miyatake K  Hashimoto Y  Hirano T  Sakata I  Minami S 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2004,66(12):1599-1601

We evaluated changes in hematology and chemical profile, and the tissue retention of hematoporphyrin derivative (HpD) following the intravenous injection in dogs. HpD at concentrations of 1, 5, 10, and 15 mg/kg was intravenously injected to 16 dogs (n=4 each) and complete blood count (CBC) and blood chemistry were performed on days 1, 3, 5, and 7 after the injection. To examine tissue retention, HpD (5 mg/kg) was administered to 15 dogs and 3 dogs were euthanized on days 1, 2, 7, 14, and 28 after the injection, respectively, to collect the skin, muscle, small intestine, spleen, kidney and liver as tissue samples. There were no significant changes in CBC and blood chemical profile except for an increase in LDH concentrations in dogs given 10 and 15 mg/kg of HpD at day 3. The levels of HpD retention in the tissues were ranked in the following order: liver > kidney > spleen > intestine > muscle > skin.  相似文献