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排序方式: 共有247条查询结果,搜索用时 15 毫秒
1.
Suzu Sakao Takafumi Fujimoto Terumasa Kobayashi Goro Yoshizaki Etsuro Yamaha Katsutoshi Arai 《Fisheries Science》2009,75(4):993-1000
Diploid gametes generated with tetraploid animals are a stepping stone to improving chromosome manipulation techniques. However,
artificially induced tetraploid individuals generally die soon after hatching. Diploid gametes could be induced by in vivo
cultures of tetraploid primordial germ cells (PGCs) through germ-line chimera. In the present study, characteristics of PGCs
were studied in inviable tetraploid masu salmon, Oncorhynchus masou. Histological observation of tetraploid embryos revealed that the same or smaller numbers of PGCs were observed and they
migrate into the genital ridges as did diploid PGCs during gonadogenesis. By whole-mount in situ hybridization using vasa messenger RNA (mRNA), 4–35 vasa-positive signals were detected in a pair of genital ridges of tetraploids. By cytological
observation of genital ridge cell suspensions, several large round cells were observed, some of which extended pseudopodia.
They also contained large nuclei and round granules in their cytoplasm, characteristics of PGCs. As the results suggest that
inviable artificial tetraploids have PGCs, we expect to achieve diploid gamete production through surrogate propagation and
tetraploid fish production. 相似文献
2.
Comparisons of energy balance and evapotranspiration between flooded and aerobic rice fields in the Philippines 总被引:3,自引:0,他引:3
Ma. Carmelita R. Alberto Reiner Wassmann Takashi HiranoAkira Miyata Ryusuke HatanoArvind Kumar Agnes PadreModesto Amante 《Agricultural Water Management》2011,98(9):1417-1430
The seasonal and annual variability of sensible heat flux (H), latent heat flux (LE), evapotranspiration (ET), crop coefficient (Kc) and crop water productivity (WPET) were investigated under two different rice environments, flooded and aerobic soil conditions, using the eddy covariance (EC) technique during 2008-2009 cropping periods. Since we had only one EC system for monitoring two rice environments, we had to move the system from one location to the other every week. In total, we had to gap-fill an average of 50-60% of the missing weekly data as well as those values rejected by the quality control tests in each rice field in all four cropping seasons. Although the EC method provides a direct measurement of LE, which is the energy used for ET, we needed to correct the values of H and LE to close the energy balance using the Bowen ratio closure method before we used LE to estimate ET. On average, the energy balance closure before correction was 0.72 ± 0.06 and it increased to 0.99 ± 0.01 after correction. The G in both flooded and aerobic fields was very low. Likewise, the energy involved in miscellaneous processes such as photosynthesis, respiration and heat storage in the rice canopy was not taken into consideration.Average for four cropping seasons, flooded rice fields had 19% more LE than aerobic fields whereas aerobic rice fields had 45% more H than flooded fields. This resulted in a lower Bowen ratio in flooded fields (0.14 ± 0.03) than in aerobic fields (0.24 ± 0.01). For our study sites, evapotranspiration was primarily controlled by net radiation. The aerobic rice fields had lower growing season ET rates (3.81 ± 0.21 mm d−1) than the flooded rice fields (4.29 ± 0.23 mm d−1), most probably due to the absence of ponded water and lower leaf area index of aerobic rice. Likewise, the crop coefficient, Kc, of aerobic rice was significantly lower than that of flooded rice. For aerobic rice, Kc values were 0.95 ± 0.01 for the vegetative stage, 1.00 ± 0.01 for the reproductive stage, 0.97 ± 0.04 for the ripening stage and 0.88 ± 0.03 for the fallow period, whereas, for flooded rice, Kc values were 1.04 ± 0.04 for the vegetative stage, 1.11 ± 0.05 for the reproductive stage, 1.04 ± 0.05 for the ripening stage and 0.93 ± 0.06 for the fallow period. The average annual ET was 1301 mm for aerobic rice and 1440 mm for flooded rice. This corresponds to about 11% lower total evapotranspiration in aerobic fields than in flooded fields. However, the crop water productivity (WPET) of aerobic rice (0.42 ± 0.03 g grain kg−1 water) was significantly lower than that of flooded rice (1.26 ± 0.26 g grain kg−1 water) because the grain yields of aerobic rice were very low since they were subjected to water stress.The results of this investigation showed significant differences in energy balance and evapotranspiration between flooded and aerobic rice ecosystems. Aerobic rice is one of the promising water-saving technologies being developed to lower the water requirements of the rice crop to address the issues of water scarcity. This information should be taken into consideration in evaluating alternative water-saving technologies for environmentally sustainable rice production systems. 相似文献
3.
When crude enzymes prepared from some vegetables and fruits were incubated with bisphenol A (2,2-bis(4-hydroxyphenyl)propane, BPA) at 37 degrees C, BPA was oxidized by crude enzymes from potato, eggplant, and lettuce. The crude enzyme prepared from potato (Solanum tuberosum) had the strongest oxidative activity for BPA. Its optimal temperature and pH were 40-45 degrees C and 8.0, respectively. More than 95% of BPA was oxidized after the incubation with potato enzyme for 60 min. BPA gave two oxidation products besides insoluble compounds during the oxidation by potato enzyme. The oxidation products were identified to be 4[1-(4-hydroxyphenyl)-1-methyl-ethyl]-benzene-1,2-diol and 4[1-(4-hydroxyphenyl)-1-methyl-ethyl]-benzene-1,3-diol. Enzymatically oxidized BPA lost the estrogen-like activity to enhance the growth of human breast cancer (MCF-7) cells. 相似文献
4.
Poxvirus infection in Nile crocodiles (Crocodylus niloticus) 总被引:1,自引:0,他引:1
G S Pandey N Inoue K Ohshima K Okada Y Chihaya Y Fujimoto 《Research in veterinary science》1990,49(2):171-176
An outbreak was encountered of numerous yellowish cutaneous nodules in one- to two-year-old farmed Nile crocodiles (Crocodylus niloticus) in Kasaba Bay Crocodile Farm at Lake Tanganyika in Zambia during 1988. Out of 4000 crocodiles of different age groups, 300 yearlings were affected and 82 of those affected died. The lesions were prominent on the head, especially around the eyelids, the nostrils, both sides of the mouth, ventral neck, ventral pale belly, limbs and the root of the tail. Histologically, the epidermal lesions revealed large focal areas of marked acanthosis accompanied by hyperkeratosis and parakeratosis. In the prickle cells, there were multiple small neutrophilic granular inclusions and large eosinophilic homogeneous cytoplasmic inclusions. Electron microscopically, there were numerous poxvirus particles and matrices in the cytoplasm of many prickle cells. Dark blue homogeneous cytoplasmic inclusions in toluidine blue sections consisted of an electron opaque matrix with mature viral particles (160 x 200 x 230 nm). Furthermore, there were clumps of granular matrix containing immature viral particles (200 x 399 nm) in the cytoplasm. Various features of viral developing processes were observed. 相似文献
5.
Fujimoto Kiyoshi Miyagi Toyohiko Kikuchi Takao Kawana Toshio 《Mangroves and Salt Marshes》1996,1(1):47-57
Mangrove habitats on Kosrae are divided into three types, i.e., an estuary or delta type, a backmarsh or lagoon type and a coral reef or tidal-flat type. Most of the mangrove forests of Kosrae have been developed during the last 2000 years by accumulating mangrove peat with the gradual sea-level rise of 1 to 2 mm/yr except the landward part of the estuary or delta type. On the other hand, during the period of rapid sea-level rise of about 10 mm/yr between 4100 and 3700 yr B.P., the mangrove forests ceased peat accumulation and retreated landward. Until 3500 yr B.P., mangrove forests were distributed only in narrow bands in the inlets. Therefore, the critical rate of mangrove peat accretion with sea-level rise is estimated at more than 2 mm/yr and less than 10 mm/yr. If the anticipated sea-level rise exceeds this critical rate, all of the mangrove forests of Kosrae will retreat landward and reduce rapidly. 相似文献
6.
Takaaki Fujimoto Kazuhito Kita Kazuko Uchiyama Makoto Kuromaru Hisashi Akutsu Kazuyuki Oda 《Journal of Forest Research》2006,11(3):157-163
Age trends in variance components and heritability of overall wood density, earlywood and latewood density, and latewood proportion
were investigated in 29-year-old trees of 19 full-sib families of hybrid larch (Larix gmelinii var. japonica × Larix kaempferi) F1. The age–age correlation and optimum selection age for these traits were also estimated and genetic and phenotypic correlations
between wood density and radial growth rate were calculated for each growth ring. Intraring wood density data were obtained
using X-ray densitometry. The coefficient of additive genetic variance was stable over all ages, whereas the coefficient of
environmental variances gradually decreased with increasing age, resulting in increases in heritability estimates with age
for overall density. The latewood proportion had the highest heritability estimates at all ages, ranging from 0.44 to 0.66.
Overall density and its various components at 28 years of age showed strong genetic correlations with their respective traits
at all younger ages. Optimum selection ages for the wood density traits ranged from 8 to 14 years, at which point maximum
gain efficiencies per year were obtained. There were negative correlations between wood density and radial growth rate at
early ages, although these relationships tended to be weaker with increasing age. These results suggest that selection at
a young age is effective for wood density, but particular care must be taken in selecting trees with an improved radial growth
rate because rapid growth will result in a low-density wood product, especially in the early growth period. 相似文献
7.
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9.
The photolysis of methyl iodide on a porous glass surface has been studied by electron paramagnetic resonance. A large number of methyl radicals can be stabilized over a wide range of temperature. The surface of porous Vycor glass is an excellent host for trapping free radicals. 相似文献
10.
Yasushi?HiramatsuEmail author Kiyohiko?Fujimoto Atsushi?Miyatake Kenta?Shindo Hirofumi?Nagao Hideo?Kato Hirofumi?Ido 《Journal of Wood Science》2011,57(1):66-70
The purpose of this study was to investigate the strength properties of glued laminated timber composed of edge-glued laminae
and to investigate the influence of edge gluing on the strength properties. Glued laminated timber composed of multiple-grade
laminae (symmetrical composition, strength grade E95-F270, 10 laminations) was produced from karamatsu (Larix kaempferi) edge-glued laminae according to the Japanese Agricultural Standard. The bending, tensile, and compressive strengths of the
glued laminated timber were measured. The average bending, tensile, and compressive strengths were 33.4, 24.5, and 35.9 MPa,
respectively, and these values are almost equal to those of glued laminated timber composed of karamatsu single-piece laminae.
It was determined that finger-joints and knots in the edge-glued laminae played a significant role in the failure of specimens.
However, the use of glued edge-joints did not appear to affect the failure of specimens. 相似文献