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排序方式: 共有361条查询结果,搜索用时 281 毫秒
351.
Zhao Zhang Takehiko Fukushima Peijun Shi Fulu Tao Yuichi Onda Takashi Gomi Shigeru Mizugaki Yuko Asano Ken'ichirou Kosugi Shinya Hiramatsu Hikaru Kitahara Koichiro Kuraji Tomomi Terajima Kazuo Matsushige 《CATENA》2008
Understanding the seasonal and regional patterns of nitrogen (N) components in the headwaters of forested watersheds is important for forests management. Here, we investigated the NO3-N concentration and its seasonal variations in the baseflow headwaters in Japanese coniferous forests with different N saturation status in five regions (i.e., Nagano, Tokyo, Aichi, Kochi and Mie). We found that the ratios of NO3-N to DON were significantly higher in the N-saturated regions including Nagano (14.1 ± 2.2) and Tokyo (16.5 ± 4.1), compared with the regions, which didn't experience N saturation including Aichi (1.4 ± 0.2), Kochi (5.1 ± 1.8), and Mie (2.2 ± 0.5). In comparison with the regions without experiencing N saturation, the relatively higher NO3-N concentration, as well as its contrastive variation between growing season and dormant season, was also characteristic of the seasonal NO3-N concentration in the N-saturated regions. Our findings have indicated that NO3-N concentration, its seasonal variations, and the ratio of NO3-N to DON, are the better and applicable indicators for evaluating N saturation status in Japanese coniferous forests. 相似文献
352.
Spontaneous hemangiosarcoma in young rats is rare. In this report, we describe a case of a spontaneous hemangiosarcoma in the spleen and liver of young rats. At necropsy, multiple pale red masses were observed in the spleen. Histopathologically, solid growth and haphazardly arranged neoplastic cells were observed, although no characteristic growth pattern was observed. In contrast, irregularly sized small slit-shaped spaces containing erythrocytes were found among the neoplastic cells. Reticular fibers incompletely surrounding the neoplastic cells were observed by silver staining. Immunohistochemistry revealed that the neoplastic cells were positive for vWF and CD34. Electron microscopic examination revealed that the neoplastic cells had erythrocytes in the lumen and Weibel-Palade bodies in the cytoplasm and were arranged along a discontinuous basal lamina. These features indicate that the tumor originated from vascular endothelial cells. Based on these results, the tumor was diagnosed as a hemangiosarcoma in the spleen and liver. 相似文献
353.
Non-random gametoclonal variation in rice regenerants from callus subcultured for a prolonged period under high osmotic stress 总被引:1,自引:0,他引:1
Gametoclonal variations were investigated in rice plants regenerated from anther-derived callus after subculture for two different
periods (4–6 and 20 weeks) in medium with two levels (292 and 438 mM) of mannitol. A high osmotic stress by mannitol in subculture
medium contributed to the maintenance of high regeneration ability. The frequency of diploid regenerants (R0 plants) increased and that of haploids decreased from callus subcultured for the longer period in medium with the higher
concentration of mannitol. R1 regenerant lines displayed variations in all six agronomical traits studied at the frequencies of 63% and 88% after subculture
for 4–6 weeks and 20 weeks, respectively. High homozygosity was suggested in most of the R1 lines for these traits by the similar levels of variance to those in the control variety. A principal component analysis
showed a skewed distribution of variants towards dwarfness and less panicle weight in the regenerants from callus subcultured
for 20 weeks with 438 mM mannitol. Two short culmn variants were shown to be due to single or double recessive mutations.
The results suggested that prolonged subculture under high osmotic stress causes non-random selection of homozygous gametoclonal
variations in rice anther culture.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
354.
Shunji Kurokawa Akito Kaga Mai Tsuda Daisuke Sekine Tomoko Shibuya 《Weed Biology and Management》2019,19(3):103-110
A canopy height‐to‐row spacing ratio (CHRSR) of 1.0 is expected to be a simple and practical onsite index for soybean growers to determine when further weed control is no longer necessary. This is decided when relative photosynthetic photon flux density (PPFD) reaches 50% under the soybean canopy. To evaluate the validity of this index, a 2‐year field experiment was conducted to compare days after sowing (DAS) to reach a relative PPFD of 50% (defined as PPFD50) and DAS to reach a CHRSR of 1.0 (defined as CHRSR1.0) in 190 accessions with different canopy architectures from a soybean core collection. A total of 104 accessions, for which final relative PPFD reached <10% in 2014, were examined for the differences between CHRSR1.0 and PPFD50. The mean and median values of the difference in 2014 were 0.02 and 2.2, respectively. Similarly, the mean and median values in 2015 were 2.8 and 2.6, respectively. Thus, CHRSR1.0 tended to be achieved slightly later than PPFD50, so a consideration was made that there would be a negligible risk of failure if growers used CHRSR1.0 to determine the termination time for weed control in the most of accessions. Although there were some accessions with a standing type of morphological characteristics or with a smaller or narrower leaf, showing negative differences between CHRSR1.0 and PPFD50 larger than 1 week, a CHRSR of 1.0 could be used to estimate PPFD50 in most of accessions without risk of failure to control weeds. 相似文献
355.
Yutaka Sato Katsutoshi Tsuda Yoshiyuki Yamagata Hiroaki Matsusaka Hiromi Kajiya-Kanegae Yuri Yoshida Ayumi Agata Kim Nhung Ta Sae Shimizu-Sato Toshiya Suzuki Misuzu Nosaka-Takahashi Takahiko Kubo Shoko Kawamoto Ken-Ichi Nonomura Hideshi Yasui Toshihiro Kumamaru 《Breeding Science》2021,71(3):291
Biological resources are the basic infrastructure of bioscience research. Rice (Oryza sativa L.) is a good experimental model for research in cereal crops and monocots and includes important genetic materials used in breeding. The availability of genetic materials, including mutants, is important for rice research. In addition, Oryza species are attractive to researchers for both finding useful genes for breeding and for understanding the mechanism of genome evolution that enables wild plants to adapt to their own habitats. NBRP-RICE contributes to rice research by promoting the usage of genetic materials, especially wild Oryza accessions and mutant lines. Our activity includes collection, preservation and distribution of those materials and the provision of basic information on them, such as morphological and physiological traits and genomic information. In this review paper, we introduce the activities of NBRP-RICE and our database, Oryzabase, which facilitates the access to NBRP-RICE resources and their genomic sequences as well as the current situation of wild Oryza genome sequencing efforts by NBRP-RICE and other institutes. 相似文献
356.
Toshihiro Wada Kyoichi Kamiyama Shinya Shimamura Ikuo Matsumoto Takuji Mizuno Yoshiharu Nemoto 《Fisheries Science》2011,77(5):785-793
Habitat utilization, feeding, and growth of a rare pleuronectid flatfish, spotted halibut Verasper variegatus, were examined in a brackish lagoon in northeastern Japan: Matsukawa-ura. The distribution and date–length data of spotted
halibut collected mainly from beam-trawl samplings during 1983–2008 indicated that age-0 juveniles [n = 25, 6.0–18.0 cm total length (TL)] and older spotted halibut (n = 71, 13.8–43.0 cm TL) inhabited almost the entire northern part of Matsukawa-ura. Comparative distribution surveys of spotted
halibut, stone flounder, and marbled flounder during 1985–1989 revealed similar distribution patterns of these flatfishes;
the highest densities were found around the central part of Matsukawa-ura, although significantly lower abundance was detected
for spotted halibut. Linear growth equations of age-0 juveniles demonstrated that spotted halibut were able to achieve high
growth after June, probably because abundant prey (e.g., mysids and gammarids) and suitable physical conditions (warmer water
temperature and lower salinity) were present. The main prey items shifted from various crustaceans including mysids, caridean
shrimps, and anomurans to brachyura Hemigrapsus spp. (≥20 cm TL). Our study shows that spotted halibut use the shallow brackish lagoon as an important nursery for juveniles,
and also as a feeding ground for young and adults. 相似文献
357.
Trimethylamine-N-oxide (TMAO) degrades to dimethylamine (DMA) and formaldehyde, which cause a decline in fish quality. Suppression of DMA
formation in frozen surimi was investigated using croaker, lizardfish, and walleye pollock. The leaching process in surimi
processing was shown to reduce not only the TMAO, iron, and taurine content, but also to reduce unidentified factors that
accelerate DMA formation in lizardfish muscle; in contrast, unidentified factors that suppress DMA formation were reduced
in croaker and pollock muscle. Sucrose, used as a cryoprotectant, was shown to decrease DMA formation in vitro, likely due
to the reduction in freezing-induced concentration of solutes. The effects of pH on DMA formation were different in minced
frozen meat among the three species. DMA formation was not observed in croaker when the pH varied between 6 and 8. On the
other hand, DMA was elevated in lizardfish under acidic conditions, and DMA formation in pollock was maximal when the pH of
the meat was neutral. Thus, the suppression of TMAO degradation by surimi processing results from the removal of TMAO, iron,
and reductants from fish meat; sucrose also reduces DMA formation. Furthermore, unidentified factors in croaker, lizardfish,
and pollock meat substantially affect DMA formation. 相似文献
358.
Murata K Nii R Sasaki E Ishikawa S Sato Y Sawabe K Tsuda Y Matsumoto R Suda A Ueda M 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2008,70(2):203-205
An adult male white eared-pheasant (Crossoptilon crossoptilon) at a Japanese zoo exhibited lethargy and emaciation. Microscopic examination of a blood smear revealed a haemosporidian parasitic infection. Based on the morphological characteristics and molecular analysis of the parasite, it was identified as Plasmodium (Bennettinia) juxtanucleare. This is the first report of P. juxtanucleare infection in bird species belonging to the genus Crossoptilon. Caution against avian malaria infection is required for the conservation of endangered bird species in zoos. 相似文献
359.
Kazuko OGATA Akira IMAI Shinya SATO Kagetomo NISHINO Shinya WATANABE Tamas SOMFAI Eiji KOBAYASHI Kumiko TAKEDA 《The Journal of reproduction and development》2022,68(1):53
During cryopreservation, spermatozoa may suffer cold and cryo-induced injuries ―associated with alterations in cell defense systems― that are detrimental to their function and subsequent fertility. This study aimed to determine the efficacy of supplementing the semen freezing extender with the antioxidant reduced glutathione (GSH) in cattle. Semen was collected from four bulls and diluted in a freezing extender supplemented with or without GSH (0, 1, 5, and 10 mM) before the cooling step of the cryopreservation process. After thawing, the quality of the frozen-thawed semen was investigated for motility, viability, acrosomal and DNA integrity, and subsequent embryo development after in vitro fertilization of bovine oocytes. Additionally, semen from one of the bulls was used to analyze semen antioxidative potential, sperm penetration into oocytes, male pronucleus formation rate, and embryo DNA integrity. The sperm quality varied among bulls after GSH supplementation. One bull had decreased sperm total motility, and two bulls had decreased sperm DNA integrity. GSH supplementation had positive effects on embryo development for three bulls. Two of them showed both improved cleavage and blastocyst formation rates, while the other one only showed an improved cleavage rate. We observed positive effects on early male pronucleus formation and no negative effects on DNA integrity and cell number in blastocyst stage embryos. Although the effect varies depending on individual bulls and GSH concentration, GSH supplementation in semen may improve in vitro embryo production from frozen semen. 相似文献
360.