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21.
Koji Ueda Keitaro Tawaraya Hideki Murayama Satoru Sato Takashi Nishizawa Tomonobu Toyomasu Tetsuya Murayama Shinpei Shiozawa Hironori Yasuda 《Applied Entomology and Zoology》2013,48(1):79-85
We investigated the effects of symbiotic association between a plant and an arbuscular mycorrhizal fungus (AMF) on the abundance of aboveground foliar-feeding insects that differed in feeding mode and their predator. We examined effects on insect abundance as the result of AMF-related changes in the quality and quantity of plants in the field. The numbers of three insects with different foliar-feeding mode (phloem feeder, chewer, and cell-content feeder) and their generalist predator Orius sauteri Poppius on soybean Glycine max (L.) Merrill with and without the AMF Gigaspora margarita Becker & Hall were compared over time. Symbiotic association between the AMF and the soybean increased shoot biomass, the concentration of phosphorus in the soybean, and the abundance of the phloem feeder Aulacorthum solani Kaltenbach, but did not affect the abundance of generalist chewers. In addition, the effects of the symbiotic association on the abundance of cell-content feeding Thrips spp. and the generalist predator O. sauteri differed between sample dates. These results indicated that the effects of the symbiotic association on the number of foliar-feeding insects depended on feeding mode and the number of predators. 相似文献
22.
Yuki Takegahara Keitaro YamanouchiKatsuyuki Nakamura Shin-ichi NakanoMasugi Nishihara 《Experimental cell research》2014
Intramuscular adipose tissue (IMAT) formation is observed in some pathological conditions such as Duchenne muscular dystrophy (DMD) and sarcopenia. Several studies have suggested that IMAT formation is not only negatively correlated with skeletal muscle mass but also causes decreased muscle contraction in sarcopenia. In the present study, we examined w hether adipocytes affect myogenesis. For this purpose, skeletal muscle progenitor cells were transfected with siRNA of PPARγ (siPPARγ) in an attempt to inhibit adipogenesis. Myosin heavy chain (MHC)-positive myotube formation was promoted in cells transfected with siPPARγ compared to that of cells transfected with control siRNA. To determine whether direct cell-to-cell contact between adipocytes and myoblasts is a prerequisite for adipocytes to affect myogenesis, skeletal muscle progenitor cells were cocultured with pre- or mature adipocytes in a Transwell coculture system. MHC-positive myotube formation was inhibited when skeletal muscle progenitor cells were cocultured with mature adipocytes, but was promoted when they were cocultured with preadipocytes. Similar effects were observed when pre- or mature adipocyte-conditioned medium was used. These results indicate that preadipocytes play an important role in maintaining skeletal muscle mass by promoting myogenesis; once differentiated, the resulting mature adipocytes negatively affect myogenesis, leading to the muscle deterioration observed in skeletal muscle pathologies. 相似文献
23.
Nobuo Okahashi Masanobu Nakata Yutaka Terao Masaya Yamaguchi Tomoko Sumitomo Shigetada Kawabata 《Biochemical and biophysical research communications》2010,391(2):1192-37577
Streptococcus sanguinis is a predominant bacterium in the human oral cavity and occasionally causes infective endocarditis. We identified a unique cell surface polymeric structure named pili in this species and investigated its functions in regard to its potential virulence. Pili of S. sanguinis strain SK36 were shown to be composed of three distinctive pilus proteins (PilA, PilB, and PilC), and a pili-deficient mutant demonstrated reduced bacterial adherence to HeLa and human oral epithelial cells. PilC showed a binding ability to fibronectin, suggesting that pili are involved in colonization by this species. In addition, ATCC10556, a standard S. sanguinis strain, was unable to produce pili due to defective pilus genes, which indicates a diversity of pilus expression among various S. sanguinis strains. 相似文献
24.
Yosuke Ichijima Ken-ichi Yoshioka Yoshiko Yoshioka Keitaro Shinohe Hiroaki Fujimori Junya Unno Masatoshi Takagi Hidemasa Goto Masaki Inagaki Shuki Mizutani Hirobumi Teraoka 《PloS one》2010,5(1)
During tumorigenesis, cells acquire immortality in association with the
development of genomic instability. However, it is still elusive how genomic
instability spontaneously generates during the process of tumorigenesis. Here,
we show that precancerous DNA lesions induced by oncogene acceleration, which
induce situations identical to the initial stages of cancer development, trigger
tetraploidy/aneuploidy generation in association with mitotic aberration.
Although oncogene acceleration primarily induces DNA replication stress and the
resulting lesions in the S phase, these lesions are carried over into the M
phase and cause cytokinesis failure and genomic instability. Unlike directly
induced DNA double-strand breaks, DNA replication stress-associated lesions are
cryptogenic and pass through cell-cycle checkpoints due to limited and
ineffective activation of checkpoint factors. Furthermore, since damaged M-phase
cells still progress in mitotic steps, these cells result in chromosomal
mis-segregation, cytokinesis failure and the resulting tetraploidy generation.
Thus, our results reveal a process of genomic instability generation triggered
by precancerous DNA replication stress. 相似文献
25.
Shin Deguchi Yumi Shimazaki Sunao Uozumi Keitaro Tawaraya Hidenori Kawamoto Osamu Tanaka 《Plant and Soil》2007,291(1-2):291-299
A field experiment was conducted to investigate the effects of white clover living mulch on the arbuscular mycorrhizal (AM)
fungus colonization of corn roots and the yield of silage corn. The following seven treatments were setup in a field that
had been kept bare by rotary tillage from August 2003 to July 2004: two white clover living mulch treatments without phosphorus
(P) application, with the white clover shoots clipped and removed or allowed to lie in place before sowing corn; one no-tillage
treatment without P application; and four rotary tillage treatments with different P application rates. White clover was broadcasted
in the living mulch treatments in August 2004. In June 2005, the white clover shoots in the living mulch treatments were clipped.
After tilling the four rotary tillage treatments, corn was sown in all the treatments. The fallow period before sowing corn
was 0 month (living mulch treatments) and 22 months (no-tillage and rotary tillage treatments). At knee high stage, the AM
fungus colonization of the corn roots and the P concentrations of the corn shoots in both the living mulch treatments were
increased relative to those in the other treatments. The yield of corn tended to increase in the no-tillage and rotary tillage
treatments with an increase in the P application rate. On the other hand, the yields of corn in the living mulch treatments
without the P application were not significantly different from the maximum yield among the no-tillage and rotary tillage
treatments. These results suggested that the white clover living mulch increased the yield of corn by facilitating the AM
fungus colonization and improving the P nutrition of corn. 相似文献
26.
Tadashi Goto Keitaro Hagiwara Nobuaki Shirai Kaoru Yoshida Hiromi Hagiwara 《Cytotechnology》2015,67(2):357-365
Polyphenol have been reported to have physiological effects with respect to alleviating diseases such as osteoporosis and osteopetrosis. We recently reported that the olive polyphenol hydroxytyrosol accelerates bone formation both in vivo and in vitro. The present study was designed to evaluate the in vivo and in vitro effects of apigenin (4′,5,7-trihydroxyflavone), one of the major polyphenols in olives and parsley, on bone formation by using cultured osteoblasts and osteoclasts and ovariectomized (OVX) mice, respectively. Apigenin markedly inhibited cell proliferation and indices of osteoblast differentiation, such as collagen production, alkaline phosphatase activity, and calcium deposition in osteoblastic MC3T3-E1 cells at concentrations of 1–10 μM. At 10 μM, apigenin completely inhibited the formation of multinucleated osteoclasts from mouse splenic cells. Moreover, injection of apigenin at 10 mg kg−1 body weight significantly suppressed trabecular bone loss in the femurs of OVX mice. Our findings indicate that apigenin may have critical effects on bone maintenance in vivo. 相似文献
27.
Mycobacteriosis, caused by the intracellular parasitism Mycobacterium sp., causes economic damages to aquaculture production in Japan, particularly in seriola fish production. Antibiotics are not effective against Mycobacterium sp. and so a potent vaccine is needed. We previously reported that BCG vaccine (Mycobacterium bovis BCG) induces adaptive immunity against Mycobacterium sp. in Japanese flounder, Paralichthys olivaceus. In a phylogenetic tree, the genes for a major antigen, the Ag85 complex, in Mycobacterium sp. TUMSAT-Msp001 are closely related to homologues in Mycobacterium ulcerans. M. bovis BCG was detected until 7 days post-injection at the injection site (muscle) and 28 days post-vaccination in spleen. Cumulative mortality of amberjack, Seriola dumerili vaccinated intramuscularly (i.m.) and intraperitoneally (i.p.) with M. bovis BCG was 32.3% and 59.5% respectively, at 24 days post-infection of Mycobacterium sp., compared to 97.8% in PBS-injected fish. The bacterial counts of Mycobacterium sp. in spleen of both i.m.-and i.p.-vaccinated fish (6.2 × 103 and 1.3 × 104 CFU/mg tissue, respectively) at 20 days post-infection were significantly lower (P < 0.01) than those of PBS-injected fish (8.0 × 106 CFU/mg). Furthermore, Immersion challenge with Mycobacterium sp. TUMSAT Msp-001 showed 50% RPS value in BCG i.m.-vaccinated fish at the end of the experiment. These results support our previous study using Japanese flounder and suggest that BCG vaccine is also effective against Mycobacterium sp. infection in amberjack. 相似文献
28.
Suzuki S Matsui T Sugawara K Asao T Kotani K 《Journal of physiological anthropology》2011,30(6):241-249
Recently, nonrestrictive and noninvasive sensing techniques to measure vital signs have been actively researched and developed. This study aimed to develop a prototype system to monitor cardiac activity using microwave radar without making contact with the body and without removing clothing--namely, a completely noncontact, remote monitoring system. In addition, heart rate and changes in heart rate variability (HRV) during simple mental arithmetic tasks were observed with the prototype system. The prototype system has a microwave Doppler radar antenna with 24 GHz frequency and approximately 7 mW output power. The experiments were conducted with seven subjects (23.00±0.82 years). We found that the prototype system captured heart rate and HRV precisely. The strong relationship between the heart rates during tasks (r=0.96), LF (cross-correlation=0.76), and LF/HF (cross-correlation=0.73) of HRV calculated from the prototype system and from electrocardiograph (ECG) measurements were confirmed. The proposed completely noncontact, remote method appears promising for future monitoring of cardiac activity as an indicator of changes in mental workload in workplaces. 相似文献
29.
Relationship between short latency stretch reflex and fascicle behavior in the soleus muscle in vivo
Objectives:Stretch reflex responses were considered to be affected by the velocity of muscle fiber lengthening and angular velocity. However, the results of previous studies in vivo and in vitro are inconsistent in this regard. The purpose of the present study was to investigate the effects of the velocity of fascicle lengthening on the amplitude of the stretch reflex for each trial with a high angular velocity and wide range of motion.Methods:Thirteen healthy men volunteered for this study. While the ankle was passively moved from 100 to 80 deg at five different angular velocities (100, 200, 300, 500, and 600 deg⋅s-1), the velocity of fascicle lengthening in the soleus muscle was measured using ultrasonography. In addition, the amplitude of the short latency stretch reflex in the soleus muscle was also measured.Results:As angular velocity increased, the amplitude of the stretch reflex and velocity of fascicle lengthening significantly increased (both p<0.001). For each trial in all subjects, the amplitude of the stretch reflex was not correlated with the velocity of fascicle lengthening at any of the angular velocities.Conclusion:In conclusion, the stretch reflex size is not related to the fascicle behavior in each trial. 相似文献
30.