Spread of invading organisms   总被引：23，自引：0，他引：23  

D. A. Andow  P. M. Kareiva  Simon A. Levin  Akira Okubo 《Landscape Ecology》1990,4(2-3):177-188

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Genetic population structure of the deep-sea whelk Buccinum tsubai in the Japan Sea     

Akira  IGUCHI  Masahiro  UENO  Tsuneo  MAEDA  Takashi  MINAMI  Isao  HAYASHI 《Fisheries Science》2004,70(4):569-572

ABSTRACT:   The purpose of the present paper was to examine the genetic population structure of Buccinum tsubai in the Japan Sea. Mitochondrial 16SrRNA gene sequence analysis was performed with specimens from various stations in the Japan Sea. Mitochondrial lineages were clearly patterned geographically in four separate areas: the Hokkaido area, the Yamagata–Toyama area, the Yamato Bank area, and the San'in area. The main distribution depth range of B. tsubai is between 200 m and 1000 m isodepths, and the horizontal distance between the 200 m and 1000 m isodepth lines represents the specific spatial scale of the habitat (SSSH). These four areas were separated either by the complete discontinuity of the SSSH area or by its narrow spatial extension. Genetic distances between the main haplotypes of each area were calculated as Jukes–Cantor distances, the value of which ranged between 0.012 and 0.017. This value seemed to be unrelated to the geographic distance. There was no tendency for clustering according to depth. In future, the morphological characters of the four lineages of B. tsubai should be compared in detail in order to elucidate significant genetic differences among them.  相似文献   

Abnormal distribution of chromosomes in the first division of nuclear transferred mouse embryos     

Kawasumi M  Anzai M  Takehara T  Mitani T  Kato H  Saeki K  Iritani A  Matsumoto K  Hosoi Y 《The Journal of reproduction and development》2007,53(3):615-622

The majority of somatic cell nuclear transferred (SCNT) embryos die before or after implantation. Many studies have focused on morphological remodeling of the donor nucleus and its associated cytoskeletal structures in the early events of nuclear transfer. However, little is known about the 2-cell stage of SCNT embryos after the first division. In this study, we compared the morphological status of chromosomal division during the 1-cell stage to the 2-cell stage in SCNT embryos with that in intracytoplasmic sperm injection (ICSI) embryos. The microtubules and cytoplasmic asters, which are related to chromatin segregation, disappeared at the pronuclear stage, although formation of the first mitotic spindle was normal in both the SCNT and ICSI embryos. However, nuclear fragmentation was observed in 30% of the 2-cell SCNT embryos and 12% of the 2-cell ICSI embryos. Nuclear fragmentation was present in both blastomeres of these embryos. No apoptotic DNA fragmentation was observed in TdT-mediated dUTP-biotin Nick End Labeling (TUNEL) assays for either the SCNT or ICSI embryos. In both the SCNT and ICSI embryos, the distribution of chromosomes in the first mitotic spindle was disturbed during the process of division from the 1-cell stage to the 2-cell stage. These results suggest that loss of SCNT embryos just before or after implantation may be due to an abnormal chromosome distribution at the 2-cell stage.  相似文献   

Seed germination responses to temperature and water availability in weedy rice     

Monrawee Fukuda  Toshiyuki Imaizumi  Akira Koarai 《Pest management science》2023,79(2):870-880

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Effects of ozonated autohemotherapy on the antioxidant capacity of Thoroughbred horses     

Nao TSUZUKI  Yoshiro ENDO  Lisa KIKKAWA  Kenji KOROSUE  Yasuyuki KANEKO  Akira KITAUCHI  Hiromu KATAMOTO  Yuichi HIDAKA  Mitsuyoshi HAGIO  Shidow TORISU 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(12):1647-1650

The performance of horses undergoing regular intense exercise is adversely affected by oxidative stress. Thus, it is important to increase antioxidant production in horses in order to reduce oxidative stress. Ozonated autohemotherapy (OAHT) reportedly promotes antioxidant production. This study aimed to evaluate the effects of OAHT on antioxidant capacity. Ten Thoroughbred horses were used in this study. After the OAHT, we collected serum samples and measured biological antioxidant potential (BAP). We found that BAP began to increase after the OAHT and was significantly higher in the OAHT group than at 3 (P<0.01) and 7 days (P<0.05) after OAHT than in the control group at 3 and 7 days after starting collection of blood samples. Therefore, it was shown that OAHT improved the antioxidant capacity of the horses.  相似文献   

Regulation of secondary follicle growth by theca cells and insulin-like growth factor 1     

Noriko SHIOMI-SUGAYA  Kouji KOMATSU  Jingwen WANG  Mamoru YAMASHITA  Fumitaka KIKKAWA  Akira IWASE 《The Journal of reproduction and development》2015,61(3):161-168

Ovaries contain follicles at various stages of development, including primordial, primary, secondary, antral and Graafian follicles. Although the growth of these follicles is controlled to maintain regular ovulation, the mechanism through which this occurs remains unclear. In our study, we found that the growth rate of cultured secondary follicles separated from mice ovaries differed between follicles. After 4 days of culture, the size of some secondary follicles was markedly increased, while that of others had either slightly increased, remained unchanged or shrunk. We compared the expression levels of growth factors between these secondary follicles and found that the growth rate of cultured secondary follicles correlated with the expression level of insulin-like growth factor 1 (Igf1) mRNA. Igf1 mRNA expression level in secondary follicles containing theca cells was higher than that in secondary follicles without theca cells, and the granulosa cell proliferation around follicles containing theca cells was increased. Furthermore, an IGF1 inhibitor also inhibited the granulosa cell proliferation, and administration of IGF1 to secondary follicles without growth promoted granulosa cell proliferation. These results indicated that the theca cells of secondary follicles induced the expression of IGF1 and promoted the follicle growth.  相似文献   

4-Nitro-3-phenylphenol has both androgenic and anti-androgenic-like effects in rats     

Jiratthiya TRISOMBOON  ChunMei LI  Akira SUZUKI  Gen WATANABE  Kazuyoshi TAYA 《The Journal of reproduction and development》2015,61(2):134-137

To investigate the effect of endocrine disruption of 4-nitro-3-phenylphenol (PNMPP) on immature male Wistar-Imamichi rats, the rat pituitary was exposed to PNMPP (10^–5–10^–9 M) for 24 h with or without gonadotropin-releasing hormone (GnRH) in experiment I. In addition, the Leydig cells (10^–5–10^–9 M) were exposed to PNMPP for 24 h with or without human chronic gonadotropin (hCG) in experiment II. Our results showed that the PNMPP at 10^–5–10^–7 M suppressed follicle-stimulating hormone (FSH) and luteinizing hormone (LH) productions from GnRH-stimulated pituitary cells. At the same time, PNMPP 10^–5–10^–7 M induced an increase in testosterone production from the Leydig cells treated with or without hCG. Based on our results, it can be concluded that that PNMPP might have both androgen agonist action by decreasing FSH and LH production in the pituitary and anti-androgenic action by increasing testosterone production in the Leydig cell.  相似文献   

Effects of an extended photoperiod on gonadal function and condition of hair coats in Thoroughbred colts and fillies     

Hirokazu KUNII  Yasuo NAMBO  Atsushi OKANO  Akira MATSUI  Mutsuki ISHIMARU  Yo ASAI  Fumio SATO  Kazuki FUJII  Kentaro NAGAOKA  Gen WATANABE  Kazuyoshi TAYA 《Journal of Equine Science》2015,26(2):57-66

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Comparison of growth and endocrine changes in Thoroughbred colts and fillies reared under different climate conditions     

Hirotoshi MIZUKAMI  Tsuyoshi SUZUKI  Yasuo NAMBO  Mutsuki ISHIMARU  Hiroshi NAITO  Kenji KOROSUE  Kentaro AKIYAMA  Kenji MIYATA  Akira YAMANOBE  Kentaro NAGAOKA  Gen WATANABE  Kazuyoshi TAYA 《Journal of Equine Science》2015,26(2):49-56

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Use of soil nonexchangeable potassium by paddy rice with clay structural changes under long-term fertilizer management     

Junta Yanai  Nanami Inoue  Atsushi Nakao  Masahiro Kasuya  Kaori Ando  Toshiya Oga  Takayuki Takayama  Hiroyuki Hasukawa  Kunihiko Takehisa  Akira Takamoto  Kazuki Togami  Tomoki Takahashi 《Soil Use and Management》2023,39(2):785-793

To prove the hypothesis that paddy rice utilizes soil nonexchangeable potassium (neK) and causes associated structural changes in clay minerals, K status and clay mineralogy of 22 surface soils from three paddy fields under long-term fertilizer management for 51–93 years were investigated. Soil neK content was determined as the difference between 1 mol L⁻¹ hot HNO₃ extractable K and 1 mol L⁻¹ ammonium acetate exchangeable K. Clay mineralogy was identified by X-ray diffraction (XRD). The radiocesium interception potential (RIP), an index of frayed edge sites in the interlayer sites of 2:1 type clay minerals, was also determined. The neK contents under the -K and NPK treatments were considerably lower than those under the unfertilized treatment in all the fields, indicating the exploitation of soil neK by rice. XRD analysis of the clay samples revealed 7% shift from the 1.0 peak to 1.4 nm one under the -K treatment compared with the unfertilized one, and the amounts of neK were negatively correlated with those of RIP (p < .01), suggesting the expansion of interlayer spaces of the 2:1 type phyllosilicates such as mica due to the release of neK. In addition, the neK content positively correlated with K balance of the long-term experiments (p < .05). The differences of neK between unfertilized K and -K treatments corresponded to 22–157 kg K ha⁻¹, or 0.42–1.68 kg K ha⁻¹ year⁻¹. In conclusion, utilization of considerable amount of soil neK under K depleted conditions should be considered to establish sustainable K management for paddy rice.  相似文献