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51.
Epigenetic abnormalities in cloned animals are caused by incomplete reprogramming of the donor nucleus during the nuclear transfer step (first reprogramming). However, during the second reprogramming step that occurs only in the germline cells, epigenetic errors not corrected during the first step are repaired. Consequently, epigenetic abnormalities in the somatic cells of cloned animals should be erased in their spermatozoa or oocytes. This is supported by the fact that offspring from cloned animals do not exhibit defects at birth or during postnatal development. To test this hypothesis in cloned cattle, we compared the DNA methylation level of two imprinted genes (H19 and PEG3) and three non‐imprinted genes (XIST, OCT4 and NANOG) and two repetitive elements (Satellite I and Satellite II) in blood and sperm DNAs from cloned and non‐cloned bulls. We found no differences between cloned and non‐cloned bulls. We also analyzed the DNA methylation levels of four repetitive elements (Satellite I, Satellite II, Alpha‐satellite and Art2) in oocytes recovered from cloned and non‐cloned cows. Again, no significant differences were observed between clones and non‐clones. These results suggested that imprinted and non‐imprinted genes and repetitive elements were properly reprogramed during gametogenesis in cloned cattle; therefore, they contributed to the soundness of cloned cattle offspring.  相似文献   
52.
Forests are one of the most important ecosystems on earth that require careful management, conservation, and sustainable exploitation. As countries have their own guideline systems, each may learn and borrow from one another’s experience. One of such countries is Japan, which has elaborate forest policies, and rich in forest cover (67%) with its forest history dating many years back. On the other hand, Kenya, with a forest cover of just 7% and its policies demonstrating notable weaknesses, has a lot to learn from Japan. Therefore, we have attempted to do a comparative analysis of forest policies, technologies, and management practices between Kenya and Japan. Results indicate that Kenya’s forest policies do not place adequate emphasis on silvicultural practices and the establishment of forest plantations, and rarely focus on sustainable biomass utilization—factors that contributed significantly to forest growth and development in Japan. Additionally, policy legislation, revision, and implementation have not been given the deserved priority in Kenya. We conclude that Kenyan forest policy would benefit from both revision and thorough implementation. We also discuss the role of indirect factors such as economic growth and availability of nonwood-based energy sources in the future of Kenya’s forests.  相似文献   
53.
Tests of compression perpendicular to the grain were carried out on laminated veneer lumber (LVL) and timber. The species tested were sugi, radiata pine, karamatsu, akamatsu, and dahurian larch; two sets of sugi specimens were tested, with the sugi LVL products being manufactured in different plants. The strength properties of the materials for different loading directions were compared for LVL and timber. At 5% compressive strain in the same materials, the average stress in the tangential direction of timber was larger than that in the radial direction for all species except for radiata pine, and the average stress in the edge-wise direction of LVL was larger than that in the flat-wise direction for all species except for radiata pine. When the stress at 5% strain was compared in the same direction, the average stress of LVL in the edge-wise direction was larger than that in timber in the tangential direction for all species, but there were no great differences between the average stress of LVL in the fl at-wise direction and that of timber in the radial direction for all species except for radiation pine. There was a close relationship between density and stress at 5% strain in LVL, especially in the edge-wise direction. For all results, radiata pine did not follow the trend of the other species; The large annual ring width of radiata pine was considered to have affected the results.  相似文献   
54.
During fertilization in mammalian species, a sperm-induced intracellular Ca2+ signal ([Ca2+]i) mediates both exit of meiosis and oocyte activation. Recently, we demonstrated in mouse oocytes that the phosphorylation levels of inositol 1,4,5 trisphosphate receptor type1 (IP3R1), the channel responsible for Ca2+ release and oscillations during fertilization, changed during maturation and fertilization. Therefore, we examined the expression and phosphorylation of IP3R1 during in vitro maturation of pig oocytes. Here, our present study shows that expression of IP3R1 protein did not change during maturation, although the phosphorylation status of the receptor, specifically at an MPM-2 epitope, did. We found that while at the beginning of maturation IP3R1 lacked MPM-2 immunoreactivity, it became MPM-2 reactive by 24 h and reached maximal reactivity by 36 h. Interestingly, the acquisition of MPM-2 reactivity coincided with the activation of p34cdc2 kinase and mitogen-activated protein kinase (MAPK), which are involved in meiotic progression. Following completion of maturation, inactivation of MAPK by U0126 did not affect IP3R1 phosphorylation, although inactivation of p34cdc2 kinase by roscovitine dramatically reduced IP3R1 phosphorylation. Neither inhibitor affected total expression of IP3R1. Altogether, our results show that IP3R1 undergoes dynamic phosphorylation during maturation and this might underlie the generation of oscillations at fertilization.  相似文献   
55.
The objective of this study was to develop a multiplex PCR detection method for the high-temperature-growing pathogens Pythium aphanidermatum, P. helicoides and P. myriotylum. Species-specific primer pairs were designed that targeted the rDNA ITS regions. The multiplex PCR was constructed with a universal primer pair for eukaryotes directed at the 18S rDNA as a positive control, in addition to the three species-specific primer pairs. When the multiplex PCR was applied to naturally infested soils, the expected species were reliably identified, suggesting that the method is suitable for the detection of the three Pythium pathogens in environmental samples.  相似文献   
56.
The aim of the present study was to provide a method for evaluating bone toxicity induced by drugs in various bones in aged rats. Male Crl:CD (SD) rats at 46 weeks of age were administered 15 mg/m(2) body surface area of doxorubicin, which effects the growth plate in weanling rats, weekly for 9 weeks by intravenous injection, and the femur, sternum, humerus and tibia were examined histopathologically. In the doxorubicin-treated group, thinning of the growth plate was remarkably observed in the proximal tibia and humerus; however, these changes were not observed in other regions. In addition, the osteoclast number per bone perimeter in the proximal tibia was significantly higher than others in control aged rat. Thus, recognizing the various histological reactions related to the time of epiphyseal closure is important for evaluating bone toxicity in aged rats.  相似文献   
57.
A mutant strain, PBA322, was constructed by electroporation of a phagemid containing the coding region of antisense RNA of the ompH gene, encoding 39 kDa capsular protein or OmpH, into the parental strain P-1059 (serovar A:3) of Pasteurella multocida, and the pathogenicity was determined in mice and chickens. Grayish colonies of the mutant, indicating loss of capsule synthesis, were observed under a stereomicroscope using obliquely transmitted light, while iridescent colonies were observed for the parental strain. Moreover, strain PBA322 showed a low amount of OmpH compared with the parental strain on SDS-PAGE. Additionally, the capsule of strain PBA322 was thinner than that of the parental strain according to electron microscopy, correlating to the attenuation against chickens. In conclusion, strain PBA322, the mutant of P. multocida strain P-1059, was completely attenuated for chickens.  相似文献   
58.
As a defense response to attacks by herbivores such as the smaller tea tortrix ( Adoxophyes honmai Yasuda), tea ( Camellia sinensis ) leaves emit numerous volatiles such as (Z)-3-hexen-1-ol, linalool, α-farnesene, benzyl nitrile, indole, nerolidol, and ocimenes in higher concentration. Attack of Kanzawa spider mites ( Tetranychus kanzawai Kishida), another major pest insect of tea crops, induced the emission of α-farnesene and ocimenes from tea leaves. The exogenous application of jasmonic acid to tea leaves induced a volatile blend that was similar, although not identical, to that induced by the smaller tea tortrix. Most of these herbivore-induced plant volatiles (HIPV) were not stored in the tea leaves but emitted after the herbivore attack. Both the adaxial and abaxial epidermal layers of tea leaves emitted blends of similar composition. Furthermore, HIPV such as α-farnesene were emitted mostly from damaged but not from undamaged leaf regions. A principal component analysis of metabolites (m/z 70-1000) in undamaged tea leaves exposed or not to HIPV suggests that external signaling via HIPV may lead to more drastic changes in the metabolite spectrum of tea leaves than internal signaling via vascular connections, although total catechin contents were slightly but not significantly increased in the external signaling via HIPV.  相似文献   
59.
ABSTRACT

Soil salinity is a major abiotic factor limiting crop production but an amendment with synthetic zeolite may mitigate effects of salinity stress on plants. The objective of the study was to determine the effects of zeolite on soil properties and growth of barley irrigated with diluted seawater. Barley was raised on a sand dune soil treated with calcium type zeolite at the rate of 1 and 5% and irrigated every alternate day with seawater diluted to electrical conductivity (EC) levels of 3 and 16 dS m?1. Irrigation with 16 dS m?1 saline water significantly suppressed plant height by 25%, leaf area by 44% and dry weight by 60%. However, a substantial increase in plant biomass of salt stressed barley was observed in zeolite-amended treatments. The application of zeolite also enhanced water and salt holding capacity of soil. Post-harvest soil analysis showed high concentrations of calcium (Ca2 +), magnesium (Mg2 +), sodium (Na+), and potassium (K+) due to saline water especially in the upper soil layer but concentrations were lower in soils treated with zeolite. Zeolite application at 5% increased Ca2 + concentration in salt stressed plants; concentrations of trace elements were also increased by 19% for iron (Fe2 +) and 10% for manganese (Mn2 +). The overall results indicated that soil amendment with zeolite could effectively ameliorate salinity stress and improve nutrient balance in a sandy soil.  相似文献   
60.
Chiyoda basin is located in Saga Prefecture in Kyushu Island, Japan, and lies next to the tidal compartment of the Chikugo River to which the excess water in the basin is drained away. Chiyoda basin has a total area of about 1,100 ha and is a typical flat and low-lying paddy-cultivated area. The main environmental issue in this basin is total nitrogen (TN) and total phosphorus (TP) load management because TN and TP, which loaded from farmlands, degrade surface water as a result of anthropogenic eutrophication. This paper presents a mathematical model of TN and TP runoff during an irrigation period in Chiyoda basin in order to elucidate the pollutant fluxes that accompany water transportation in paddy fields and drainage canals, and to evaluate pollutant removal from the study area to the Chikugo River. First, the water flow and the algorithm of gate operation were simulated by a continuous tank model and the accuracy of the model was then evaluated by comparing the simulated water levels with observed ones during an irrigation period. The observed and simulated water levels were in good agreement, indicating that the proposed model is applicable for drainage and water supply analyses in flat, low-lying paddy-cultivated areas. Second, the TN and TP runoff during an irrigation period was simulated based on the TN and TP loads that were determined by observed data in paddy fields. For TN runoff, the simulated results and observed data were in good agreement whereas for TP runoff, the simulated results were higher than the observed data. However, if the settled TP within the paddy tank was calculated as 6%, then the simulated results and the observed data were in good agreement. We concluded that TN runoff from paddy field to the drainage canal system was not affected much by the sediment related process. The present study could provide farmers and managers with a useful tool for controlling the water distribution in an irrigation period, and the TN and TP loads in the downstream area as well as the Chikugo River.  相似文献   
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