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排序方式: 共有146条查询结果,搜索用时 31 毫秒
91.
92.
Shusaku Takagi Hisashi Murata Takanobu Goto Hideo Hatate Makoto Endo Hirofumi Yamashita Hisashi Miyatake Masaharu Ukawa 《Fisheries Science》2011,77(2):235-244
This study was conducted to investigate the mechanism of green liver symptom induction and the effect of dietary taurine supplementation
on growth performance in juvenile red sea bream fed non-fishmeal diets based on soy protein concentrate (SPC). Juvenile fish
(initial BW 72 g) were fed for 20 weeks on SPC diets supplemented with taurine at levels of 0, 1.0, and 2.0%. In the taurine-unsupplemented
SPC diet group, specific growth rate (SGR) and feed conversion ratio (FCR) were significantly inferior (P < 0.001), and incidence of green liver was observed in 70% of fish. In this group, hepatopancreatic and plasma taurine concentrations
were lowest (P < 0.05), hepatopancreatic content of bile pigments was highest (P < 0.05), and osmotic tolerance of erythrocytes was inferior (P < 0.05) among the dietary treatment groups. Serum osmolality of all treatment groups was at similar levels. These physiological
abnormalities as well as SGR and FCR were improved by dietary taurine supplementation. These results indicate that the mechanism
for induction of green liver symptom is bile pigment overproduction due to increased hemolysis because erythrocytes become
osmotically fragile due to dietary taurine deficiency. Taurine supplementation of SPC diets is essential for maintaining normal
physiological condition and growth performance in juvenile red sea bream. 相似文献
93.
Matsumoto H Ito K Yonekura K Tsuda T Ichiyanagi T Hirayama M Konishi T 《Journal of agricultural and food chemistry》2007,55(6):2489-2496
Many studies on the bioavailability of polyphenols have been reported. However, the relative urinary excretions of AC are also low, ranging from 0.004% to 0.1%. By contrast, other polyphenols show higher urinary excretion levels. Here, we studied the enhancing effects of phytic acid (IP6) on absorption of blackcurrant anthocyanins (BCAs) in rats and humans. In rats after oral administration of BCAs (as 241 mg of AC/kg body weight) in IP6 (0%, 0.25%, 0.5%, 1%, 2.5%) solution, the ACs recovery in urine was increased dependent on IP6 dose. These results suggest that the IP6 enhances gastrointestinal absorption of ACs. At the further analysis of IP6 enhancement effect in rat, whereas BCAs were normally passed through the stomach and duodenum within 2 h, in IP6 group, after 2-6 h post-administration, stomach and jejunum content's weights were specifically heavy, and large amounts of ACs were also detected in stomach, duodenum, and jejunum. These results suggested that the mixture of BCAs and IP6 reduced the gastrointestinal motility. Prolongation of ACs residue in gastrointestinal tract then caused the enhancing effects of IP6 on absorption of AC. In the human study, each subject was orally administrated a BCA beverage containing BCA concentrate (AC 4 mg/kg body weight), 1% of IP6, and 1% of sodium citrate as a pH stabilizer. Both the plasma level and the urinary excretion of AC were increased as compared to BCA administration without IP6. AC intake with IP6 may increase the bioavailability of AC to the comparative level as other polyphenols. Yet, phytic acid, being a strong chelator of important minerals, contributes to mineral deficiencies. An interference with iron uptake has been reported. Safety tests are therefore necessary before high dose IP6 can be used in foods. 相似文献
94.
Akira Haraguchi Chiaki Hasegawa Akiko Hirayama Hisaya Kojima 《European Journal of Soil Biology》2003,39(4):191-196
Decomposition rates of peat and cellulose, and oxygen consumption rates were studied in three minerotrophic peat mires in Sasakami, central Japan. These mires had differences in topography, pedology and hydrology. Two dominant vegetation types in each mire, a Sphagnum palustre–S. cuspidatum community and a Rhynchospora fauriei community, were selected as the decomposition study sites. The objective of this study was to examine how the environmental and vegetational differences in mires correlate with the activity of decomposition. Decomposition rates of peat and the rates of cellulolysis were studied in the field for 6 months. Oxygen consumption rates were measured in the field using a closed chamber equipped with an oxygen electrode. In situ peat decomposition rates showed significant differences among the three mires, whereas in situ cellulolysis rates showed significant differences between communities. Peat mass loss rates positively correlated with the nitrogen and carbon concentration of the peat. Cellulolysis rates positively correlated with the range of water table fluctuation. Oxygen consumption rates showed significant negative correlation with the averaged and minimum water table depth, and positive correlation with the range of water table fluctuation. There was a significant positive correlation between cellulolysis rates and oxygen consumption rates. These are useful parameters for evaluating how the decomposition activity in soil depends on the vegetation types and water conditions. 相似文献
95.
We investigated how genetic factors and pollen shortage affect seed production in a small population of Magnolia stellata, a threatened insect-pollinated tree. We used microsatellite and manual pollination techniques, and compared a small population to a large one. Compared to the large population, the small population showed low allelic variation and had an FIS significantly greater than 0 in adults, indicating that genetic deterioration, including genetic drift and inbreeding, may have occurred in adults. Manual self-pollination lowered seed production relative to manual cross-pollination to a different extent between populations: δ (the magnitude of inbreeding depression due to self-fertilization) was lower in the small population than in the large population. However, under natural pollination, the estimated embryo mortality rates after ovules self-fertilized were similar between the two populations because the primary selfing rate was higher in the small population. The ovule mortality rate due to pollen shortage and that due to factors independent of pollen shortage and selfing were both approximately 10% higher in the small population, suggesting that pollen transfer may have decreased and genetic deterioration effects may have increased in that population. These factors reduced seed production in the small population (female reproductive success = 0.3%) compared to the large population (2.6%). Our results suggest that seed production in the small population of M. stellata is strictly limited by elevated pollen shortage, selfing, and genetic deterioration in adults, which accelerate the risk of extinction. 相似文献
96.
97.
Atsushi Sakai Takahisa Hirayama Shigenori Oshioka Yasumasa Hirata 《Journal of Forest Research》2006,11(4):253-265
Large areas of previously clear-cut conifer plantations have been recently abandoned in Japan. We investigated the vegetation
in the clear-cut sites and examined the environmental factors affecting species composition of the vegetation. We set up 32
study sites, each composed of several study plots (5 × 5 m), ranging from 220 m to 1060 m a.s.l. Elevation and warmth index
(cumulated thermal quantity) were the primary factors affecting the species composition, with clear-cut areas showing a smaller
effect in the nonmetric multidimensional scaling (NMS) ordination. Two-way indicator species analysis (TWINSPAN) divided the
32 study sites into ten vegetation groups, clustering the sites by elevation or by postharvest disturbances (i.e., replanting
or browsing of Sika deer). Deciduous trees and shrubs were significant in the vegetation cover at higher elevations, while
they were less so in areas of high Sika deer populations. We also investigated the abundance of old-growth species, which
are expected to regenerate where the clear-cut site is abandoned. Evergreen Quercus and Castanopsis saplings were abundant at low elevations (<600 m), suggesting that they will successfully regenerate. The sapling densities
of Abies firma and Betula grossa were significantly large where a clear-cut site was adjacent to natural forest, which is expected to act as a seed source.
This implies that degraded deciduous forests may establish after clear-cutting at intermediate and high elevations (>600 m)
if the clear-cut site is distinct from seed sources. It is argued that the preservation of natural forests is critical for
the regeneration of old-growth species. 相似文献
98.
The shear strength of dowel-type timber connections with multiple slotted-in steel plates was estimated based on European
yield theory. The values calculated based on the yield theory were compared with experimentally obtained results. An experiment
was performed on dowel-type timber connections with two and three slottedin steel plates under lateral loads parallel to the
grain. The yield mode of the dowel-type connection assumed in this study corresponds approximately to the failure mode of
the connection obtained from the experiment. The shear strength of the dowel-type connections calculated based on the yield
theory showed good agreement with the results for shear strength obtained in the experiment. The yield theory was useful for
estimating the shear strength of the doweltype connection with multiple slotted-in steel plates. The shear strength of the
dowel-type connection was greatly affected by the spacing of the steel plates, the number of steel plates, and the timber
thickness. The values of these parameters that showed the proper shear strength of the dowel-type connection could be estimated
based on the yield theory.
Part of this paper was presented at the 9th Timber Engineering Forum of the Japan Timber Engineering Society, December 2005 相似文献
99.
100.
Ozaki H Esaki H Takemoto K Ikeda A Nakatani Y Someya A Hirayama N Murase T 《Veterinary microbiology》2011,150(1-2):132-139
To investigate the effects of rearing practices of commercial broiler chickens on the incidence of antimicrobial resistance in commensal Escherichia coli isolates, fecal E. coli isolates obtained in 4 farms were screened for anitimicrobial resistance. Ten E. coli isolates were recovered from each of the fecal samples collected from 10 birds in the farms at the ages of 2 days, 14-17 days, and 47-50 days. In 2 out of the 4 farms, no antimicrobials were used during the rearing period. In the other two farms, following collection of the fecal samples at 14 and 15 days of age, oxytetracycline (OTC), sulfadimethoxine (SDMX), and tylosin were given to birds on one farm and SDMX was used in the other. Isolates resistant to ampicillin and OTC that were obtained from an untreated flock at different sampling times were closely related to each other by pulsed-field gel electrophoresis patterns (PFGE) of XbaI-digested chromosomal DNA. PFGE analysis together with in vitro conjugation experiments suggested that diversity of resistance phenotypes within a clone may be resulted from the acquisition and loss of R-plasmids in an untreated and a treated flock. The numbers of resistance phenotypes observed among fecal isolates increased during the growth of the chickens in all the farms. The results in the present study suggest that persistence of commensal E. coli strains resistant to antimicrobials even in the absence of antimicrobial administration. It is also hypothesized that horizontal transmission of resistance determinants resulted in the emergence of different resistance phenotypes in those farms. 相似文献