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11.
Dao Ha Viet Takata Yoshinobu Omura Takuo Sato Shigeru Fukuyo Yasuwo Kodama Masaaki 《Fisheries Science》2009,75(2):507-512
Previously we reported that a significant level of domoic acid, a causative toxin for amnesic shellfish poisoning, was detected
in bivalves belonging to a genus Spondylus from various tropical Asian countries. These findings indicate that causative plankton species for domoic acid widely distribute
in these areas. In the present study, we monitored seasonal change of domoic acid level of Spondylus versicolor in association with that of plankton samples in Nha Phu Bay, Khanh Hoa, Vietnam from December 2004 to October 2005. The toxicity
of S. versicolor showed distinct seasonal variation. During the period when domoic acid level of S. versicolor was increasing, a significant level of domoic acid was detected in the plankton samples, showing the correlation between
these two parameters. These findings show that plankton causative for domoic acid occurred in the bay, and S. versicolor accumulate domoic acid during a bloom of the toxic plankton by food web transfer. 相似文献
12.
We demonstrate a method for evaluating the appropriate number of samples required to estimate plant species richness in different
forest types within a forested landscape. In each of 36 plots (0.1 ha each) from 5 forest types (deciduous broad-leaved secondary
forest and 4 categories of coniferous plantation classified according to stand age) in central Japan, 40 quadrats of 1 × 1 m
were set in a regular pattern; the total number of quadrats in each forest type ranged from 200 to 400. In each plot, the
number of observed species in 40 quadrats ranged from 60 to 80% of the number of species estimated by the rarefaction method
for each forest type. Sampling 30 quadrats detected approximately 90% of the observed species in each plot that were detected
using 40 quadrats. In specific functional groups (i.e., tall trees and weed species), the ratios of both tall trees and weed
species to all species were at equilibrium for 30 or more quadrats. For fewer than 30 quadrats these ratios were highly variable.
No significant differences were found among forest types in the ratio of the observed number of species in each plot to the
estimated number of species calculated using the rarefaction method, and in sampling efficiency estimated by use of non-parametric
estimators. We concluded that the number of samples does not need to be changed according to forest type or plantation stand
age in the studied landscape, and that the method used to evaluate the number of samples could be useful. 相似文献
13.
14.
Sthitmatee N Kataoka Y Sawada T 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2011,73(11):1445-1451
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
15.
Michishita M Akiyoshi R Yoshimura H Katsumoto T Ichikawa H Ohkusu-Tsukada K Nakagawa T Sasaki N Takahashi K 《Research in veterinary science》2011,91(2):254-260
There is increasing evidence for the presence of cancer stem cells in several solid tumors, and these cancer stem cells have a potential role in tumor initiation, aggression, and recurrence. The stem cell-like properties of spheres derived from canine mammary tumors remain largely elusive. We attempted to induce sphere formation using four cell lines of canine mammary adenocarcinoma, and characterized the spheres derived from a CHMp line in vitro and in vivo. The CHMp-derived spheres showed predominantly CD44+CD24− population, higher expression of stem cell-related genes, such as CD133, Notch3 and MDR, and higher resistance to doxorubicin compared with the CHMp-derived adherent cells. Xenograft transplantations in nude mice demonstrated that only 1 × 104 sphere cells were sufficient for tumor formation. Use of the sphere assay on these sphere-derived tumors showed that sphere-forming cells were present in the tumors, and were maintained in serial transplantation. We propose that spheres derived from canine mammary adenocarcinoma cell lines possess a potential characteristic of cancer stem cells. Spheres derived from canine mammary tumors could be a powerful tool with which to investigate novel therapeutic drugs and to elucidate the molecular and cellular mechanisms that underlie tumorigenesis. 相似文献
16.
Tetsuo Asai Kaori Masani Chizuru Sato Mototaka Hiki Masaru Usui Kotaro Baba Manao Ozawa Kazuki Harada Hiroshi Aoki Takuo Sawada 《Acta veterinaria Scandinavica》2011,53(1):52
A total of 318 Escherichia coli isolates obtained from different food-producing animals affected with colibacillosis between 2001 and 2006 were subjected to phylogenetic analysis: 72 bovine isolates, 89 poultry isolates and 157 porcine isolates. Overall, the phylogenetic group A was predominant in isolates from cattle (36/72, 50%) and pigs (101/157, 64.3%) whereas groups A (44/89, 49.4%) and D (40/89, 44.9%) were predominant in isolates from poultry. In addition, group B2 was not found among diseased food-producing animals except for a poultry isolate. Thus, the phylogenetic group distribution of E. coli from diseased animals was different by animal species. Among the 318 isolates, cefazolin resistance (minimum inhibitory concentrations: ≥32 μg/ml) was found in six bovine isolates, 29 poultry isolates and three porcine isolates. Of them, 11 isolates (nine from poultry and two from cattle) produced extended spectrum β-lactamase (ESBL). The two bovine isolates produced blaCTX-M-2, while the nine poultry isolates produced blaCTX-M-25 (4), blaSHV-2 (3), blaCTX-M-15 (1) and blaCTX-M-2 (1). Thus, our results showed that several types of ESBL were identified and three types of β-lactamase (SHV-2, CTX-M-25 and CTX-M-15) were observed for the first time in E. coli from diseased animals in Japan. 相似文献
17.
Maria Portia P. Briones Kohji Hori Milagrosa R. Martinez-Goss Genji Ishibashi Takuo Okita 《Plant foods for human nutrition (Dordrecht, Netherlands)》1997,50(4):287-294
The physical properties, amount of oxalate-oxalic acid soluble substances (OOSS), protein and in vitro protein digestibility
ofNostoc commune from the Philippines and Japan were determined. The samples were the spherical type from the Philippines (PS), the dry field
discoid type from the Philippines (PD), and the dry field discoid type from Japan (JD). The discoid types, PD and JD, regardless
of origin showed higher settling volume in water (SV) and bulk density than PS. The OOSS values obtained for all samples were
directly related to SV and bulk density. The WHC level was highest in PS. This desirable characteristic makes PS a technologically
potential sample for large-scale food production applications in the future. Protein and in vitro protein digestibility varied
significantly among all samples. In general, the algal samples examined posses desirable physical properties which are expected
to be related to physiological functions. 相似文献
18.
Kohji Hori Genji Ishibashi Takuo Okita 《Plant foods for human nutrition (Dordrecht, Netherlands)》1994,45(1):63-70
Nutritional quality of the castor meal protein isolate detoxified using boiling and lime cum heat treatments was evaluated in experiments with rats. Chemical scores of both the treated isolates were similar, threonine being the first limiting amino acid. The calculated nutritional indices (essential amino acid index) and PER were higher for the boiled isolate (1.3) than that was for lime-cum-heat treated (0.86). Though, necropsy examination of organs did not reveal any abnormalities, histopathological changes were observed in the organs — liver, kidney, intestine that could be attributed to the deficiency of essential amino acids in the detoxified castor protein isolates. 相似文献
19.
Takuo Hishi Rieko Urakawa Naoaki Tashiro Yuka Maeda Hideaki Shibata 《Biology and Fertility of Soils》2014,50(2):343-356
This study aimed to evaluate the spatial patterns of soil nitrogen (N) transformations in relation to slope aspect and position, and to investigate the main factors controlling N transformation patterns during both the growing and dormant seasons in cool-temperate deciduous natural forests and larch plantations in eastern Hokkaido, northern Japan. Net rates of N mineralization (NRminN) and of nitrification (NRnit) in surface soils on north-facing and lower slopes were higher than those on south-facing and upper slopes, whereas the net rate of ammonium-N production (NRamm) on south-facing and upper slopes was higher than that on north-facing slopes in both the natural forests and larch plantations. Both NRminN and NRnit were higher in the growing than in the dormant season, whereas NRamm was higher in the dormant season. The soil C/N ratio, water content, soil pH and frequency of freeze–thaw cycles were important variables affecting N transformation patterns in any season. In relation to seasonality, the solar radiation index, daily temperature range and earthworm biomass were important controlling factors only during the growing season, and watershed area and soil N concentration only during the dormant season, suggesting that biological control accompanied with wet–dry events were important factors affecting N transformations during the growing season, but that run-off water and chemical controls were important determinants of spatial variation in N transformations during the dormant season. 相似文献
20.
Heterogeneity of individual roots within the fine root architecture: causal links between physiological and ecosystem functions 总被引:6,自引:0,他引:6
Takuo Hishi 《Journal of Forest Research》2007,12(2):126-133
This review covers the heterogeneity in functions within the fine root architecture in order to clarify the multiple functions
of fine roots. Many fine root characteristics, such as anatomy, physiology, morphology, and their consequences for the ecosystem,
differ among root ages and ontogenetic branching hierarchies. Individual root age can be characterized by tissue development,
with the main tissues developing from primary to secondary tissues. The physiological characteristics of individual roots,
such as absorptivity and respiration rates, decrease with increasing branching order, mainly because of aging and tissue development.
The C/N ratio and lignin and suberin contents also increase with branching order because of root aging. Morphological characteristics,
such as diameter and specific root length, differ among root orders because of both aging and ontogenetic differences. The
mortality of individual roots differs among branching orders and root diameters. The life cycles of roots in the fine root
architecture, that is, ephemeral and perennial, indicate ontogenetic differences in functions and demographic traits, similar
to those for leaves and branches in shoots. In addition, differences in individual root life cycles may affect the root chemical
composition, in turn, affecting the decomposition rate. Future studies should seek to identify heterorhizic units in mortality
related to anatomical, physiological, and morphological differences for various species. The decomposition processes of each
mortality unit within the fine root architecture are also important in understanding the link between physiological and ecosystem
functions. 相似文献