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Previously, we reported that phyllochron of rice greatly fluctuated in the course of development under natural conditions. The present study was carried out to examine the phyllochron dynamics using the five near-isogenic lines (NILs) for heading time and the recurrent parent. The change of phyllochron was investigated under four different controlled conditions regarding daylength and temperature. Growth duration (days to heading) showed a large variation among different growth regimes as well as genotypes. Changes of phyllochron were evaluated in the genotypes by using a quartic polynomial regression that was well fitted to the change of phyllochron in the present controlled environments as previously observed under natural conditions. Phyllochron began to drastically increase after around the 5th phytomer order and decreased with the progress of reproductive development in similar manners under different environments. The pattern of phyllochron change varied from a flat to non-flat shape. The shape of the equation was affected by genotypes as well as daylengths and temperatures. In addition, the shape was closely related to the growth duration (days to heading) of the genotype, suggesting that the phyllochron might internally increase depending on the genotype controlling the heading date. Therefore, the present results showed that the sufficient examination of phyllochron dynamics is necessary for understanding a variation in the heading date of rice. 相似文献
3.
The repeated elements called phytomers, which consist of leaf, node, internode and axillary bud, play an important role in
the development of modular organization in plants. Rice has the striking feature that the rate of the phytomer production
is closely synchronized with the rate of leaf emergence (phyllochron). We examined developmental changes of phyllochron by
using 10 near-isogenic lines (NILs) showing diversified growth durations in rice. The NILs were established by backcrosses
with a strain practically insensitive to photoperiod, and they consisted of early- or late-flowering NILs whose differences
of growth duration were caused by the combinations of alleles at 6 loci. The developmental patterns of phyllochron were evaluated
by means of a quartic polynomial, which fitted well in most cases. The results indicated that phyllochron greatly changed
during development, especially in late-flowering NILs as well as the recurrent parents, although the fluctuation of phyllochron
was not so marked in the early-flowering NILs. Thus, the developmental change of phyllochron was highly dependent upon the
genotypes and/or growth duration; however, it was associated with neither floral initiation nor temperature, indicating that
the change of phyllochron might reflect internal or physiological changes which occur during the life cycle of rice.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Yoshinori TAKAMI Kyung-Ok NAM Youki TAKAKI Sho KADEKARU Chizuka HEMMI Tsuyoshi HOSOYA Yumi UNE 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2021,83(8):1234
Ophidiomycosis is an emerging infectious disease caused by the fungus Ophidiomyces ophiodiicola, which has been affecting wild and captive snakes in North America, Europe, and Australia. We report 12 cases of suspected ophidiomycosis in captive colubrid snakes in Japan. Pathological and microbiological examinations were performed, and the results confirmed the diagnosis of ophidiomycosis in two snakes, which indicated that the remaining sympatrically raised snakes also had ophidiomycosis since they exhibited similar lesions. This is the first report of ophidiomycosis in Asia caused by O. ophiodiicola. To prevent the expansion of ophidiomycosis in the natural environment in Japan, there is a need to evaluate the ophidiomycosis carrier status of imported snakes, the pathogenicity of the infection in native snakes, and the prevalence and distribution of O. ophiodiicola in wild and captive snakes. Measures also must be taken to prevent endemicity globally. 相似文献
5.
Yoshitaka Kubojima Seiichi Kanetani Takeshi Fujiwara Youki Suzuki Mario Tonosaki Hiroshi Yoshimaru Hiroharu Ikegame 《Journal of Wood Science》2008,54(6):443-450
A dead tree of Pinus armandii Franch. var. amamiana (Koidz.) Hatusima (abbreviated to PAAm) was obtained from a natural habitat on Tanega-shima Island and various properties
of its wood were investigated. Grain angle was measured and soft X-ray analysis was undertaken to obtain the density in each
annual ring. Unit shrinkage and dynamic properties were measured by shrinkage, bending, and compression tests. Variations
of wood properties in the radial direction, relationships of wood properties to density, and annual ring width were examined.
Roughly speaking, variations in the radial direction of the grain angle, twist angle by drying, Young’s modulus and strength
in static bending, absorbed energy in impact bending, compressive Young’s modulus, compressive strength, and compressive proportional
limit corresponded to the variation of annual ring width. As a result, it was determined that if PAAm is afforested artificially
for the purposes of lumber production and conservation, the annual rings of logs should not be too widely spaced. Wood properties
of PAAm were similar to those of Japanese black pine (Pinus thunbergii Parl.), which is another representative pine on Tanegashima Island.
This study was presented in part at the 56th Annual Meeting of the Japan Wood Research Society, Hiroshima, August 2007 相似文献
6.
Nahoko IEDA Yoshihisa UENOYAMA Yoko TAJIMA Tomoko NAKATA Masatoshi KANO Yousuke NANIWA Youki WATANABE Shiori MINABE Junko TOMIKAWA Naoko INOUE Fuko MATSUDA Satoshi OHKURA Kei-ichiro MAEDA Hiroko TSUKAMURA 《The Journal of reproduction and development》2014,60(4):312-316
Puberty is associated with an increase in gonadotropin secretion as a result of an increase in gonadotropin-releasing hormone
(GnRH) secretion. Kisspeptin is considered to play a key role in puberty onset in many mammalian species, including rodents,
ruminants and primates. The present study aimed to determine if changes in hypothalamic expression of the KISS1
gene, encoding kisspeptin, are associated with the onset of puberty in pigs. The animals (n=4 in each group) were perfused with 4%
paraformaldehyde at 0, 1, 2, 3 and 4 months old, as prepubertal stages, and at 5 months old, as the peripubertal stage, following
each blood sampling. KISS1 gene expressions in coronal sections of brains were visualized by in
situ hybridization. Plasma luteinizing hormone (LH) was measured by radioimmunoassay. KISS1 mRNA
signals were observed in the arcuate nucleus (ARC) at all ages examined without any significant difference in the number of
KISS1-expressing cells, indicating that the KISS1 gene is constantly expressed in the ARC
throughout pubertal development in pigs. The plasma LH concentration was the highest in 0-month-old piglets and significantly
decreased in the 1- and 2 month-old groups (P<0.05), suggesting a developing negative feedback mechanism affecting gonadotropin
release during the prepubertal period. Considering the potent stimulating effect of kisspeptin on gonadotropin release in
prepubertal pigs, kisspeptin secretion rather than kisspeptin synthesis may be responsible for the onset of puberty in pigs. 相似文献
7.
Tatsuo NAKAHARA Yoshihisa UENOYAMA Akira IWASE Shinya OISHI Sho NAKAMURA Shiori MINABE Youki WATANABE Chikaya DEURA Taro NOGUCHI Nobutaka FUJII Fumitaka KIKKAWA Kei-ichiro MAEDA Hiroko TSUKAMURA 《The Journal of reproduction and development》2013,59(5):479-484
Puberty in mammals is timed by an increase in gonadotropin-releasing hormone (GnRH)
secretion. Previous studies have shown involvement of the two neuropeptides,
kisspeptin and neurokinin B (NKB), in controlling puberty onset. Little is known
about the role of the other key neuropeptide, dynorphin, in controlling puberty
onset, although these three neuropeptides colocalize in the arcuate kisspeptin
neurons. The arcuate kisspeptin neuron, which is also referred to as the KNDy neuron,
has recently been considered to play a role as an intrinsic source of the GnRH pulse
generator. The present study aimed to determine if attenuation of inhibitory
dynorphin-kappa-opioid receptor (KOR) signaling triggers the initiation of puberty in
normal developing female rats. The present study also determined if stimulatory
NKB-neurokinin 3 receptor (NK3R) signaling advances puberty onset. Female
Wistar-Imamichi rats were weaned and intraperitoneally implanted with osmotic
minipumps filled with nor-binaltorphimine (nor-BNI), a KOR antagonist, or senktide, a
NK3R agonist, at 20 days of age. Fourteen days of intraperitoneal infusion of nor-BNI
or senktide advanced puberty onset, manifested as vaginal opening and the first
vaginal estrus in female rats. Frequent blood sampling showed that nor-BNI
significantly increased luteinizing hormone (LH) pulse frequency at 29 days of age
compared with vehicle-treated controls. Senktide tended to increase this frequency,
but its effect was not statistically significant. The present results suggest that
the inhibitory input of dynorphin-KOR signaling plays a role in the prepubertal
restraint of GnRH/LH secretion in normal developing female rats and that attenuation
of dynorphin-KOR signaling and increase in NKB-NK3R signaling trigger the onset of
puberty in female rats. 相似文献
8.
Naohiro Uwatoko Atsushi Onishi Yuji Ikeda Manabu Kontani Atsushi Sasaki Kazuki Matsubara Youki Itoh Yoshio Sano 《Euphytica》2008,163(2):167-175
Flowering time is affected not only by photoperiod sensitivity (PS) but also by basic vegetative growth (BVG) and optimum
photoperiod (OP), although their developmental and genetic relationships are not well understood. The present study was carried
out in rice to examine to what extent these three developmental components are modified by the three flowering time genes,
Se1 (= Hd1), Ef1 and e1 (= m-Ef1), which are known to contribute to flowering time in temperate and tropical regions of rice cultivation. Photoperiodic response
curves were estimated under controlled conditions of different growth regimes, using eight near-isogenic lines possessing
different combinations of the alleles at the three loci. The results showed that each of the components is greatly affected
by the main effect of the genes, temperature and their epistasis, indicating that none of the three genes controls flowering
time by altering any single component in PS, BVG or OP. Epistasis was detected more frequently among the three genes than
reported before, suggesting that epistasis contributes to flowering time by changing PS, BVG and OP differently. The comparison
of the nucleotide sequences suggested that Ef1 is the same as Early heading date 1 (Ehd1). Since the two genes Se1 (= Hd1) and Ef1 (= Ehd1) are known to up-regulate the rice homolog of Arabidopsis
FT, it is suggested that the detected epistasis may respond to diverse environments by modulating the CO/FT system conserved in flowering plants. 相似文献
9.
Shear modulus of several kinds of Japanese bamboo obtained by flexural vibration test 总被引:1,自引:0,他引:1
Yoshitaka Kubojima Yoko Inokuchi Youki Suzuki Mario Tonosaki 《Journal of Wood Science》2010,56(1):64-70
The vibrational properties of Japanese bamboo were examined. To obtain the Young’s modulus and shear modulus, a flexural vibration test and a longitudinal vibration test were conducted. The Young’s modulus with vibration in the R-direction was smaller than that measured in the longitudinal vibration test E l . This was due to the shift of the neutral axis to the outer layer. On the other hand, the Young’s modulus with vibration in the T-direction was close to E l . Hence, an adequate Young’s modulus should be used for each use of bamboo. The shear moduli of the LR and LT planes of bamboo were similar to those of beech. There were high correlations between shear moduli of the LR and LT planes and density. 相似文献
10.
We investigated a method for measuring the refining degree of bamboo charcoal using an alternating current. The bamboo charcoal
was made under heating conditions of 400°–900°C (set temperature) and 0—3 h (holding time at each set temperature). The qualities
of the bamboo charcoal could not be estimated from the yield, and electric tests were required. The effect of the variation
in sample thickness on the impedance could be ignored. Attaching two plate electrodes to the same surface of a specimen enabled
high accuracy and practical use. The impedance was found to be a suitable index for estimating the refining degree of the
bamboo charcoal, such as the specific electric resistance. We believe that bamboo changes from an insulator to a conductor
suddenly when processed at 600°–750°C for 0–2 h. It is possible that the integral of temperature with time in a specimen during
heating is useful for approximately estimating impedance. 相似文献