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排序方式: 共有150条查询结果,搜索用时 31 毫秒
1.
Noriyuki Koizumi Atsushi Mori Takuya Mineta Eiji Sawada Keiji Watabe Takeshi Takemura 《Paddy and Water Environment》2017,15(4):723-730
Fecal DNA samples from the red-eared slider and Reeves’ pond turtle, suspected pests of lotus root paddies, were used to identify the plant species eaten by these turtles in order to develop a strategy for rural ecosystem conservation. The fecal samples were obtained from young and adult individuals (mostly female) of both species living in agricultural canals surrounding lotus root paddies in Tokushima Prefecture, Japan. The samples were screened for the presence or absence of DNA from nine plant species using PCR and plant species-specific primers for the rbcL gene of chloroplast DNA. In the red-eared slider, our analysis identified seven plant species in the fecal DNA samples of adults and three plant species in those of young individuals. In Reeves’ pond turtle, our analysis identified two plant species from adult fecal samples and one species from those of young individuals. Thus, adult red-eared sliders consume a greater range of plants than young red-eared sliders or Reeves’ pond turtles. Both turtle species, independently of age, consumed lotus plants and were likely to cause feeding damage to lotus roots. Considering the plant species detected in adult red-eared sliders and these plant habitats, we suggest that this adult turtle is likely to travel between the agricultural canals and the lotus root paddies. These findings will help the development of strategies for preventing damage to lotus roots by these turtles; furthermore, they indicate that fecal DNA analysis will be applicable to investigation of the feeding habits of other animal species. 相似文献
2.
Noda S Sawaki M Shiraishi K Yamasaki K Yamaguchi R 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2002,64(4):315-319
The age-related changes of vaginal opening, body weight, the weights of the uterus and ovary, together with histological examination, serum 17beta-estradiol (E2) and progesterone levels were examined in intact female Crj:CD (SD) IGS rats between 21 and 36 days of age to understand the basic biological profile of changes of the female genital system during sexual maturation in the rat for female pubertal assays. With the beginning of the elevation of serum E2 level from 28 days of age, all parameters except body weight started to show drastic change until 31 days of age. The highest incidence of vaginal opening was recorded at 34 days of age. On macroscopic examinations, a number of rats showed uterine imbibition but vaginal opening. Immediately after the confirmation of the vaginal opening, the genital systems of three rats were observed microscopically. Both ovaries already had multiple corpora lutea, and degeneration of endometrial epithelial cells was observed. In conclusion, we obtained essential data on genital tract development of female Crj:CD (SD) IGS rats for in vivo screening assays that will contribute to detect potential endocrine active chemicals. In addition, it is assumed that the first ovulation precedes or occurs simultaneously with vaginal opening. 相似文献
3.
Sato J Okada K Fukuda S Sato R Yasuda J Naito Y 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2002,64(7):653-655
The correlation between the serum hydroxyproline concentration and serum activity levels of TRAP and BALP was examined in 41 cows. The correlated coefficient (r) was 0.6391 for TRAP and 0.3147 for BALP, respectively. Judging from the significant correlation to the serum hydroxyproline concentration, serum TRAP activity is an index for bone metabolism in cows. Serum TRAP activity was therefore measured in 205 healthy cows (2-9 years old) in order to observe the changes in bone resorption with aging and milk production. TRAP levels differed slightly between group A (< or =4 yrs) and B (5 yrs< or =) at the same stage of lactation. The activity levels rose slightly at the height of lactation stage and during the dry stage. 相似文献
4.
Uyanga Ariya Ken-Ya Hamano Takushi Makimoto Shu Kinoshita Yasuaki Akaji Yuko Miyazaki Muneto Hirobe Keiji Sakamoto 《Journal of Forest Research》2016,21(2):73-83
Dendrochronological approaches enable us to understand forest stand dynamics by estimation of disturbance history and age structure. The present study was conducted in an old-growth beech forest in a forest reserve in western Japan. Increment cores were taken for tree ring analysis from all canopy trees in a 50 m × 130 m study plot. Radial growth release criteria were developed to identify significant growth releases in each tree ring series and to characterize the disturbance history of the study site. The age structure of the forest was indicative of continuous establishment by Fagus crenata and simultaneous establishment by Magnolia obovata. A variety of low-intensity disturbances were identified in each decade, especially after the 1900s, but the occurrence of high-intensity catastrophic disturbance was rare, and likely played an important role in maintaining species diversity in the existing forest canopy. The results also suggest that F. crenata regenerates gradually before and after both large- and small-scale disturbances, whereas M. obovata and Betula grossa regenerate only after large-scale catastrophic disturbances. 相似文献
5.
Naoko?MikiEmail author Kosei?Otsuki Keiji?Sakamoto Takashi?Nishimoto Ken?Yoshikawa 《Journal of Forest Research》2003,8(3):153-161
To elucidate the differences in the leaf water relations of Pinus densiflora Sieb. et Zucc. growing in different soil moisture conditions, we examined the pressure-volume curve and the diurnal changes in the stomatal conductance, the transpiration rate, and the leaf water potential. The leaf water relations were compared using field-grown 40-year-old pine trees growing on the upper and lower parts of a slope. We also compared the leaf water relations of potted 4-year-old saplings growing at pF 4.2 and pF 1.8 soil moisture levels for almost 1 year. The values of the ratio of symplasmic water at turgor loss point to symplasmic water at saturated point (Vp/Vo) and bulk modulus of elasticity () of both the adult trees on the upper part of the slope and the potted saplings growing on pF 4.2 soil moisture were higher than those values of both the adult trees on the lower part of the slope and the potted saplings growing on pF 1.8 soil moisture, respectively. The field-grown adult tree and the potted saplings growing under long-term water stress tended to reduce their stomatal conductance in response to the acute soil drying. It is suggested that P. densiflora growing under long-term water stress rapidly closed its stomata in response to soil drying and avoided losing water, and could also rapidly absorb water with reducing water loss because of the decrease in the leaf pressure potential derived from the high values. 相似文献
6.
Keiji?SakamotoEmail author Naoko?Miki Taiyo?Tsuzuki Takashi?Nishimoto Ken?Yoshikawa 《Journal of Forest Research》2003,8(4):303-309
In pine forests damaged by pine wilt disease, in western Japan, the effect of protection regimes of pine trees on the stand dynamics were examined in the following four stands: (1) lightly damaged stand (age 30–40 years) with no procedure in operation for protecting pine trees; (2) severely damaged stand (age 30–40 years) with no procedure in place for protecting pine trees; (3) severely damaged stand (age 50 years) with a selective cutting of infected trees; (4) severely damaged stand (age 30–40 years) with a selective cutting of infected trees. All the stands had been abandoned before the pine wilt disease damage. The understory structure of the severely damaged stand with no protection procedure was similar to that of the lightly damaged stand. Frequent invasion by tree species and acceleration in the growth of understory trees occurred after the dieback in the selective cutting stand. These results suggest that a deficiency in the canopy layer caused by the dieback resulted in low disturbance intensity in the early stages after the dieback, but the selective cutting increased the intensity by the reduction in the understory as well as the canopy layer. The intensity of the disturbance in the selective cutting stands was larger in the younger stand because it had a higher density of selectively cut pine trees. The different stand structure of pine forests occurred after the dieback because the intensity of the disturbance varied as a result of the selective cutting operation and the stand age. 相似文献
7.
Ayumi HASEGAWA Keiji MOCHIDA Toshiko TOMISHIMA Kimiko INOUE Atsuo OGURA 《The Journal of reproduction and development》2014,60(3):187-193
Successful in vitro fertilization (IVF) in mice has been achieved using spermatozoa at concentrations
specifically optimized for the experimental conditions, such as species and source of spermatozoa. Although IVF in mice is
mostly performed using about 80–500 µl drops, it is expected that the number of spermatozoa used for insemination can be
reduced by decreasing the size of the IVF drops. The present study was undertaken to examine the extent to which the number
of spermatozoa used for IVF could be reduced by using small droplets (1 µl). We devised the experimental parameters using
frozen–thawed spermatozoa from C57BL/6 mice in anticipation of broader applications to other mouse facilities. We found that
as few as 5 spermatozoa per droplet could fertilize oocytes (1 or 3 oocytes per droplet), although the fertilization rates
were low (13–15%). Practical fertilization rates (> 40%) could be achieved with frozen-thawed C57BL/6J spermatozoa, which
are sensitive to cryopreservation, when 20 sperm per droplet were used to inseminate 3 oocytes. Even with spermatozoa from a
very poor quality suspension (10% motility), about 25% of oocytes were fertilized. Our calculations indicate that the number
of inseminated spermatozoa per oocyte can be reduced to 1/96–1/240 by this method. In two separate embryo transfer
experiments, 60% and 47%, respectively, of embryos developed to term. Our microdroplet IVF method may be particularly
advantageous when only a limited number of motile spermatozoa are available because of inadequate freezing-thawing or genetic
reasons. 相似文献
8.
Gaudi BS Bennett DP Udalski A Gould A Christie GW Maoz D Dong S McCormick J Szymanski MK Tristram PJ Nikolaev S Paczynski B Kubiak M Pietrzynski G Soszynski I Szewczyk O Ulaczyk K Wyrzykowski L;OGLE Collaboration Depoy DL Han C Kaspi S Lee CU Mallia F Natusch T Pogge RW Park BG;MuFUN Collaboration Abe F Bond IA Botzler CS Fukui A Hearnshaw JB Itow Y Kamiya K Korpela AV Kilmartin PM Lin W Masuda K Matsubara Y Motomura M Muraki Y Nakamura S Okumura T Ohnishi K Rattenbury NJ Sako T Saito T Sato S 《Science (New York, N.Y.)》2008,319(5865):927-930
Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency of solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing analogs of all the solar system planets except Mercury. We report the detection of a multiple-planet system with microlensing. We identify two planets with masses of approximately 0.71 and approximately 0.27 times the mass of Jupiter and orbital separations of approximately 2.3 and approximately 4.6 astronomical units orbiting a primary star of mass approximately 0.50 solar mass at a distance of approximately 1.5 kiloparsecs. This system resembles a scaled version of our solar system in that the mass ratio, separation ratio, and equilibrium temperatures of the planets are similar to those of Jupiter and Saturn. These planets could not have been detected with other techniques; their discovery from only six confirmed microlensing planet detections suggests that solar system analogs may be common. 相似文献
9.
Haiping Lai Hiroyuki Kawashima Junko Shindo Keiji Ohga 《Water, air, and soil pollution》2001,130(1-4):1843-1848
We analyze the history of acid rain in China over the last three decades in the light of the relationship between China and Japan. China has been aware of the problem of acid rain and has been conducting scientific research since the late 1970s. However, little effort has been put into practical countermeasures. In the early 1990s, acid rain was re-evaluated as an international environmental problem. Meanwhile, Japan became concerned about trans-boundary air pollution from China. What is important is that Japan's concern strongly influences China's acid rain policy. In the context of growing international concern for environmental problems, China has taken remarkable steps to control acid rain. In this respect, dealing with acid rain is an issue of national pride for China. 相似文献
10.
Keiji Tanaka Minoru Nakajima Norio Kurihara 《Pesticide biochemistry and physiology》1981,16(2):149-157
The factors which cause lindane resistance in the Third Yumenoshima strain, a strain of house flies highly resistant to insecticides, were studied using hexadeuterated lindane. Hexadeuterated lindane has the same physicochemical properties as lindane, but the former is much less biodegradable than the latter. The LD50 ratio of lindane to hexadeuterated lindane in this strain, deuterium isotope effect on LD50 values, was larger than that in SNAIDM, a susceptible (nonresistant) strain. The penetration rates of labeled and nonlabeled lindane through the insect cuticle were about the same for both strains. Thus, penetration rate does not cause resistance. The metabolic degradation of lindane in the resistant strain in vivo occurred much faster than in the susceptible strain. This was also the case for lindane degradation processes in vitro such as microsomal oxidation and glutathione conjugation. In both strains, significant isotope effects were observed in the degradation rates in vitro of labeled and nonlabeled lindane. Therefore, principal biodegradation and detoxication pathways should include reactions which cleave the CH bonds. When the much less biodegradable d6 counterpart of lindane was applied to both strains, the susceptible strain became much more highly intoxicated than the other within 20 to 30 min. This indicates that a combination of both greater degradability and probably lower sensitivity at the action site are the main factors underlying resistance in the Third Yumenoshima strain. 相似文献