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51.
Summary By using polyclonal and monoclonal antibodies against connectin (titin) which stain the A-I junctional area and the A-band domain (polyclonal anti-connectin and monoclonal 4C9) and the I-band domain (monoclonal SM1), the developmental relationship of this elastic protein with sarcomeric proteins, especially myosin and-actinin, was examined in embryonic chick cardiac myocytesin vitro under fluorescence microscopy. During premyofibril stages, I-Z-I proteins were detected first (-actinin dots and diffuse actin [phalloidin and anti-troponin C] staining), and later in these areas connectin and myosin dots appeared with nearly identical distribution. Somewhat later, phalloidin-positive nonstriated fibrils were observed in a straight course. They were always reactive with antibodies against a-actinin and troponin C, but unreactive or only weakly reactive with anticonnectin and anti-myosin. Initially,-actinin dots were aligned along these fibrils but did not form striations. As they aggregated to form Z-bands, connectin and myosin started to exhibit typical striations (doublets and A-bands, respectively). No difference in the staining pattern was observed with two kinds of monoclonal antibodies against different domains of connectin filaments (4C9 and SM1) at early phases. As myosin staining began to show clear A-bands, connectin epitopes became arranged in polarized positions. We conclude that primitive I-Z-I complexes appear prior to the assembly of connectin and myosin filaments and then connectin filaments, developing intimately and coordinately with myosin, become associated with the-actinin lines. Thus it appears that the putative elastic protein connectin plays some role in integrating myosin filaments with the preexisting I-Z-I brushes. The occasional absence of connectin and A-bands between two Z-bands, beyond both of which clear sarcomeres have been formed, indicates that connectin is not a preformed scaffold of myofibrils on which sarcomeric proteins accumulate. 相似文献
52.
Ca2+-and voltage activated K+ channel in apical cell membrane of gallbladder epithelium fromTriturus
Y. Maruyama H. Matsunaga T. Hoshi 《Pflügers Archiv : European journal of physiology》1986,406(6):563-567
The presence of Ca2+- and voltage-activated K+ channels was directly demonstrated in the apical cell membrane of gallbladder epithelium by patch-clamp single-channel current recording. In K+-depolarized epithelial cells, negative pipette potentials induced outward current steps when the patch-pipette was filled with Na+-rich solution and these current steps were not affected by the presence or absence of Cl–. When K+-rich solution was in the pipette and K+-depolarized cells were examined, the current-voltage relations were linear with a single-channel conductance of 140 pS and polarity was reversed at 0 mV. In excised inside-out membrane patches, raising the free Ca2+ concentration of the medium facing the inner side of the membrane from 10–7 to 10–6 M evoked a marked increase in open state probability of the channels without affecting the elementary current steps. This suggests that intracellular Ca2+ as a second messenger plays a crucial role in the regulatory mechanism of the membrane potential by modulating the high-conductance apical K+ channels. 相似文献
53.
W. Maruyama K. Ichimi Y. Fukui J. Yan Y. Zhu H. Kamiunten T. Omura 《Archives of virology》1997,142(10):2011-2019
Summary. The nucleotide sequence of the genome segment 2 (S2) of rice gall dwarf virus (RGDV), a phytoreovirus, when compared with
the amino acid sequence of a component protein of the virus, showed that S2 potentially encoded a 127K minor outer capsid
protein. This 127K protein designated as P2 and the 127K minor outer capsid protein (also termed P2) of rice dwarf virus (RDV)
are similar in size, located in the outer capsid, and have well-conserved predicted polypeptide sequences, suggesting similar
functions. Infectivity to insect vector cell monolayers of RGDV was maintained and the P2 protein was retained irrespective
of carbon tetrachloride (CCl4) treatment. This is in contrast to the infectivity of RDV which is removed along with P2 protein following CCl4 treatment. RGDV with P2 was acquired by vector insects and transmitted to host plants, although RDV lacking P2 could not
be transmitted to plants as previously published. These results imply that RDV and RGDV require P2 proteins for virus infectivity
to vector insects.
Received January 6, 1997 Accepted May 14, 1997 相似文献
54.
55.
Endo Y Yamauchi K Tsutsui Y Ishihara Z Yamazaki F Sagawa S Shiraki K 《The Japanese journal of physiology》2002,52(5):421-427
To investigate the possible involvement of the sympathetic nervous system in pressor response during water drinking, muscle sympathetic nerve activity (MSNA), blood pressure (BP), and heart rate (HR) were continuously measured in healthy young volunteers throughout the experiments of a 5-min control, 2 min of drinking 500 ml water, and a 28-min recovery. To avoid the effects of water passing through the oropharyngeal and esophageal regions and/or effects of swallowing, an equal amount of water was directly infused to the stomach through a stomach tube for 2 min. Water drinking caused a transient increase in mean arterial pressure (MAP) and HR immediately after drinking (DeltaMAP, 12.6 +/- 2.1 mmHg; DeltaHR, +19.9 +/- 1.7 beats/min at the peak). An abrupt decrease of MSNA was observed directly during water drinking (Deltaburst rate, -6.9 +/- 1.3 bursts/min; Deltatotal activity, -2,606 +/- 491 U/min), and it increased to the baseline level thereafter. Gastric infusion had little or no effect on MAP, HR, and MSNA. The present study demonstrated that a pressor response during water drinking was associated with the attenuation of MSNA and not generated by gastric infusion of water at the same rate as in this drinking manner. In conclusion, the rapid rise in BP might be caused through stimulations from the oropharyngeal region, swallowing-induced factors, and/or a feedforward mechanism by a central descending signal from the higher brain centers. 相似文献
56.
Ken SAITO Hideo SHIMIZU Takeshi YOKOYAMA Katsuya KAWATA Takanori MATSUMURA Yasuhiko MORIOKA 《Pathology international》1983,33(2):249-256
Four cases of Ischemic enterocolitis without arterio–occlusive lesion were described. Three cases were associated with sigmoid colon carcinomas. Ischemic lesions developed anal to the carcinomas in two cases, and oral to sigmoidostomy to relieve intestinal obstruction by carcinoma in one case. One other case was associated with inguinal hernia. Grossly, ischemic lesions involved relatively short intestinal segments, and the ischemic colonic lesions were not related to teniae coli. Extensive veno–occlusive lesions were discovered in a case of ischemic stricture of the ileum, which had been incarcerated in the right inguinal hernia. Reversible mechanical occlusion of the intestinal vessels caused by transient or recurrent intestinal strangulation is the most probable cause of these ischemic lesions., ACTA PATHOL. JPN. 33: 249–256, 1983. 相似文献
57.
Parotid glands of 5-day-old rats were maintained in DM-153 synthetic, serum-free medium in organ culture for 24 to 48 hr. Differentiation of acinar cells in vitro, as revealed by an increase in amylase activity in the gland and in the culture fluid, as well as by the immunocytochemical demonstration of amylase in the acinar cells, was accelerated by insulin, prednisolone, and l-thyroxine added to the culture medium. The potent tumor promoter 12-O-tetradecanoylphorbol-13-acetate (10?7M) inhibited both the unstimulated and hormone-stimulated differentiation of the gland without causing cellular degeneration or necrosis. 相似文献
58.
Suppression of development of diabetes in NOD mice by lactate dehydrogenase virus infection 总被引:1,自引:0,他引:1
Izumi Takei Yoshiaki Asaba Tomohiro Kasatani Taro Maruyama Kenji Watanabe Tatsuo Yanagawa Takao Saruta Toshiharu Ishii 《Journal of autoimmunity》1992,5(6):665-673
It has been reported that lactate dehydrogenase virus (LDV) selectively infects a subpopulation of macrophages, thereby affecting the immune system. We studied the effects of LDV infection on the development of diabetes in non-obese diabetic (NOD) mice. Five-week-old female NOD mice were infected with LDV (10(8) ID50/mouse) and observed until 23 weeks of age. None of the 21-LDV-infected mice developed diabetes, whereas 10/14 (71.4%) uninfected mice did. Although the subpopulations of T cells and the percentage of Mac1-positive cells in the NOD murine spleen and the number of harvested peritoneal macrophages were unaffected by LDV infection, the proportions of Ia-positive peritoneal macrophages were significantly decreased in LDV-infected compared with uninfected mice (1.1 +/- 0.2%, 6.5 +/- 2.9%; P < 0.01). In LDV-infected NOD mice, insulitis of the same grade as that seen in uninfected NOD mice was observed. In another experiment, 3, 5, 10 or 16-week-old female NOD mice were infected with LDV. None of the mice infected with LDV at 3, 5 or 10 weeks of age developed diabetes and only one of six infected at 16 weeks of age did. These findings indicate that LDV infection suppresses the development of diabetes in female NOD mice by reducing the capacity of Ia-positive macrophages, and suggest that the development of human type 1 diabetes may be suppressed by certain viral infections. 相似文献
59.
Y. Maruyama A. Nishiyama T. Izumi N. Hoshimiya O. H. Petersen 《Pflügers Archiv : European journal of physiology》1986,406(1):69-72
The K+ channel in rat parotid gland acinar cells were investigated by ensemble current noise analysis in single isolated cells employing the giga-seal whole cell current recording mode. Sets of 20–40 identical de- and hyperpolarization voltage steps were applied and the resultant current records were processed by computer to obtain the mean and the variance of the current. The time-course of the mean current could be fitted by the sum of two exponentials, suggesting a 3-state model. The simplest plausible hypothesis is a model with one open and two closed states. Assuming this model, the relationship between the variance (2) and the mean current (I) could be fitted by the function 2/I=i–I/N. The estimated single channeli/V-relations were similar to those taken from single channel current recordings, and the size of the population of channels per cell (N) was 76±26 (n=12). The validity of the model was tested by a successful simulation of the time-course of the variance. 相似文献
60.
Hideo Higuchi Toshitada Yoshioka Koscak Maruyama 《Journal of muscle research and cell motility》1988,9(6):491-498
Summary Skinned fibres from frog semitendinosus muscle were stretched in relaxing solution from a sarcomere length of 2.5 m to greater sarcomere lengths, and then shortened back to the original length. Fibres could be stretched up to sarcomere lengths of 3.3 m, and reshortened fully. If the original stretch was to a sarcomere length greater than 3.3 m, the extent of recovery was dependent on the magnitude of the stretch and the number of times the stretch/shorten cycle was repeated. When the original stretch was to sarcomere lengths beyond overlap of the thick and thin filaments, the thin filaments did not re-enter the thick filament array but buckled at the A-I junction. If these fibres were subsequently activated and contracted, the thin filaments re-entered the thick filament array, taking up approximately their former positions, and allowing reduced development of isometric tension.Finally, the present observations support the view that calcium-induced interactions of actin and myosin filaments in the presence of ATP play an important role in the organization of myofibrillar structure during differentiation (compare Hayashiet al. 1977; Shimada & Obinata, 1977). 相似文献