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Toshihide Hirao Masashi Murakami Jiro Iwamoto Hino Takafumi Hiroyuki Oguma 《Ecological Research》2008,23(1):189-196
The effect of disturbance on local communities may operate within the context of the spatial landscape. We examined the scale-dependent
effects of windthrow disturbance caused by a large typhoon on three arthropod communities in a temperate forest of Japan.
Canopy arthropods were collected by beating foliage, forest-floor arthropods were collected by sweeping the vegetation, and
flying arthropods were collected in Malaise traps. To assess the “functional spatial scale” at which arthropods responded
to tree-fall disturbance, the gap rate was quantified at different spatial scales by sequentially enlarging the radius of
a circular landscape sector in 10-m increments from 10 to 500 m. We then analyzed the responses of order richness and abundance
to the gap rate for each arthropod community. The spatial scale of the significant best-fitting model, which was selected
from the models fitted to the gap rate at stepwise spatial scales, was regarded as the arthropod-specific functional spatial
scale. Arthropod order richness was not dependent on the gap rate. In contrast, arthropod order abundance depended significantly
on the gap rate in many orders, but varied in the response direction and functional spatial scale. These order-specific, scale-dependent
responses to tree-fall gaps could complicate interactions among organisms, leading to complex community organization. An understanding
of the spatial processes that link the use of space by organisms with the spatial scale at which ecological processes are
experienced is required to elucidate the responses of populations, communities, and biotic interactions to disturbances in
a spatial landscape context. 相似文献
64.
A new species of nematode, Angiostoma namekuji n. sp. (Angiostomatidae: Rhabditida), is described from the intestinal lumen of the terrestrial slug Philomycidae gen. sp. collected from Oshiba Island in the Seto Inland Sea, Hiroshima Prefecture, Japan. The new species is recognized by the following characteristics: body length 2,782–3,599 (mean 3,240) μm (male); 4,666–5,532 (5,030) μm (female); lateral field present; pharyngeal corpus with valves in the bulb; male with short tail, c = 35–57 (48), with one denticle; and seven pairs of genital papillae arranged as 1+2/3+1; female with tail having small denticles on distal tip; uterus c.50% of the body size; each ovary long, starting near vulva, not coiled, reflexed and reaching uterus; ovaries not crossing each other. Our phylogenetic tree based on sequences of the nuclear 28S ribosomal RNA gene supported the generic allocation of the new species in Angiostoma Dujardin, 1845. 相似文献
65.
Taeko Nakadai Kumie Nojima Ikuo Kobayashi Kayoko Sato Nakahiro Yasuda Hiroaki Mitani Okio Hino 《Biological Sciences in Space》2004,18(3):177-178
Eker rat known as a model of hereditary renal carcinoma (RC) is an example of Mendelian dominantly inherited predisposition to a specific cancer in experimental animals. We investigate the effects of simulated space radiation on carcinogenesis using HIMAC. We estimated RBE from the Eker rats exposed to the heavy-ions, C (290 MeV/u) and Fe (500 MeV/u) ions, comparing to the effects of X-ray irradiation. Pregnant rats were exposed to C and Fe ions and X-rays with a single dose of 1 Gy, 2 Gy, 3 Gy on day 19 of gestation. The offspring were sacrificed at 8 weeks of age. We evaluated organ weights and tumor genesis. The weights of thymus, lung, liver, spleen were found to be no difference from the control at 1 Gy irradiation but 50% decrease at 3 Gy irradiation. We found in the irradiated animal that kidney, brain and testis were very sensitive organs of which the weight decreased to approximately 80% at 1 Gy and to 40% at 3 Gy irradiations. Based on the dose-response relationship of the radiation-induced carcinoma, averaged RBE ware calculated to be 1.1 for C-ion, 1.6 for Fe-ion. 相似文献
66.
Molecular Characterization and Expression of Pyruvate Formate-Lyase-Activating Enzyme in a Ruminal Bacterium, Streptococcus bovis 下载免费PDF全文
To clarify the significance of the activation of pyruvate formate-lyase (PFL) by PFL-activating enzyme (PFL-AE) in Streptococcus bovis, the molecular properties and gene expression of PFL-AE were investigated. S. bovis PFL-AE was deduced to consist of 261 amino acids with a molecular mass of 29.9 kDa and appeared to be a monomer protein. Similar to Escherichia coli PFL-AE, S. bovis PFL-AE required Fe2+ for activity. The gene encoding PFL-AE (act) was found to be polycistronic, and the PFL gene (pfl) was not included. However, the act mRNA level changed in parallel with the pfl mRNA level, responding to growth conditions, and the change was contrary to the change in the lactate dehydrogenase (LDH) mRNA level. PFL-AE synthesis appeared to change in parallel with PFL synthesis. Introduction of a recombinant plasmid containing S. bovis pfl and the pfl promoter into S. bovis did not affect formate and lactate production, which suggests that the activity of the pfl promoter is low. When the pfl promoter was replaced by the S. bovis ldh promoter, PFL was overexpressed, which caused an increase in the formate-to-lactate ratio. However, when PFL-AE was overexpressed, the formate-to-lactate ratio did not change, suggesting that PFL-AE was present at a level that was high enough to activate PFL. When both PFL-AE and PFL were overexpressed, the formate-to-lactate ratio further increased. It is conceivable that LDH activity is much higher than PFL activity, which may explain why the formate-to-lactate ratio is usually low. 相似文献
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Cloning of differentially expressed genes in highly and low metastatic rat osteosarcomas by a modified cDNA-AFLP method. 总被引:17,自引:0,他引:17
T Fukuda A Kido K Kajino M Tsutsumi Y Miyauchi T Tsujiuchi Y Konishi O Hino 《Biochemical and biophysical research communications》1999,261(1):35-40
To identify differentially expressed genes between highly and low metastatic rat transplantable osteosarcomas, we applied a modified AFLP (amplified fragment length polymorphisms) method for cDNA subtraction. The specific point of our modification is selective amplification using suppression PCR technique after restriction enzyme cutting. Our cDNA-AFLP gave high reproducibility (about 95%) in mRNA patterns and enabled us to clone four dominantly expressed genes in a highly metastatic tumor line. Three showed homology with known genes, encoding Ki-67, a proliferation-associated effective marker of malignancy, type IV collagen alpha-3, a major component of basement membrane, and KIAA77 for which the function is unknown. Although one fragment showed no database homology, we revealed a derivation from the rat homologue of the Drosophila melanogaster diaphanous gene (Dia) by cloning of longer cDNA. Dia genes, known to affect actin filament formation, are downstream effectors of Rho small GTPase. The results suggest that alterations in the expression of cytoskeletal protein, basement membrane elements, and proliferative markers may be important for metastasis of osteosarcomas. 相似文献
70.
Jing Zhang Saki Taniguchi Hironori Ito Kazuhiro Iiyama Madoka Hino Tsutomu Katayama 《Bioscience, biotechnology, and biochemistry》2017,81(10):1937-1940
A toxin-antitoxin system, vp1842/vp1843, locates within a superintegron on the Vibrio parahaemolyticus genome chromosome I whose toxin gene vp1843 encodes a DNA nicking endonuclease. We found that the vp1843 expression in Escherichia coli cells strongly induced chromosomal DNA degradation. On the basis of these observations, we discuss a possible physiological role of vp1842/vp1843 in V. parahaemolyticus. 相似文献