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921.
Sequence of an unusually large protein implicated in regulation of myosin activity in C. elegans 总被引:36,自引:0,他引:36
The Caenorhabditis elegans gene unc-22 encodes a very large muscle protein, called twitchin, which consists of a protein kinase domain and several copies of two short motifs. The sequence of twitchin has unexpected similarities to the sequences of proteins of the immunoglobulin superfamily, cell adhesion molecules and vertebrate muscle proteins, including myosin light-chain kinase. These homologies, together with results from earlier genetic and molecular analyses, indicate that twitchin is involved in a novel mechanism of myosin regulation. 相似文献
922.
M. Sumida 《Cellular and molecular life sciences : CMLS》1994,50(9):860-866
In order to elucidate cytogenetically the cause of male sterility in intraspecific hybrids ofRana japonica, the behavior of chromosomes in the first meiosis was observed in spermatocytes from male reciprocal hybrids between two populations from Hiroshima and Ichinoseki. In the parental Hiroshima and Ichioseki populations, 2530 (96.7%) meiotic spreads had 13 bivalents and 78 (3.0%) contained 12 bivalents and two univalents, whereas in reciprocal hybrids only 337 (7.0%) contained 13 bivalents and the other 4445 (93.0%) had 2–26 univalents. A total of 31647 (93.4%) bivalents was ring-shaped and the other 2234 (6.6%) were rod-shaped in both parental populations, whereas in reciprocal hybrids 26352 (57.1%) and 19819 (42.9%) bivalents were ring- and rod-shaped, respectively. These results show that meiotic chromosomes of reciprocal hybrids are characterized by a remarkable increase in univalents and rod-shaped bivalents. 相似文献
923.
K. Ikemoto T. Utsunomiya M. A. Ball M. Kobayashi R. B. Pollard F. Suzuki Ph.D. 《Cellular and molecular life sciences : CMLS》1994,50(5):456-460
The antiviral activity of Shigyaku-to (TJS-109), a traditional Chinese herbal medicine, was investigated in mice infected with herpes simplex virus type 1 (HSV-1). TJS-109 is a combination of the medicinal plant extracts fromZingiberis siccatum rhizoma,Aconiti tuber andGlycyrrhizae radix in a specific proportion. Mice infected with a 10 LD50 dose of HSV-1 were treated with TJS-109 orally at doses of 1.25 to 20 mg/kg 2 days before, and 1 and 4 days after the infection. The treated groups had 80% (1.25 mg/kg), 40% (5 mg/kg) and 23% (20 mg/kg) mortality rates 25 days after the infection as compared with a 100% mortality rate in control mice treated with saline. When HSV-1 infected mice (recipients) received CD8+T cell fractions derived from spleens of mice treated with TJS-109 (donors), 70% of recipients survived, as compared with 0% survivors in the groups of mice treated with saline, B cell fractions, CD4+ T cell fractions or macrophage-enriched fractions prepared from the same donors. TJS-109 did not show any virucidal activities against HSV-1 or any virostatic activities on the growth of HSV-1 in Vero cells. These results suggest that TJS-109 protected mice exposed to lethal amounts of HSV-1 through the activation of CD8+ T cells. 相似文献
924.
H. Miyamoto N. Manabe Y. Akiyama T. Watanabe M. Sugimoto E. Sato 《Cellular and molecular life sciences : CMLS》1994,50(9):808-811
The morphometric parameters of spermatogenic cells in a mouse strain prone to accelerated senescence (SAM-P), a novel murine model of spontaneously promoted aging, were compared with those of a SAM resistant strain (SAM-R) after birth until 40 weeks (mean life span of SAM-P). A mixture of gonocytes and spermatogonia were present in the testis in 1-week-old mice, and no gonocytes were observed in 2-week-old mice. At 6 weeks of age, the absolute number of spermatogonia in SAM-P was 27% greater than that in SAM-R, whereas the cell number in 40-week-old SAM-P was 17% less than in SAM-R. Primary spermatocytes were first observed in 3-week-old animals, and the cell numbers in SAM-P at 3, 5 and 6 weeks were 78%, 31% and 25%, respectively, greater than in SAM-R, whereas the cell number in SAM-P at 40 weeks was 30% less than SAM-R. Round spermatids were first observed in all SAM-P at 4 weeks old, but 20% of SAM-r had no spermatids and the rest had only a few. At 5 and 6 weeks old, the absolute numbers of round spermatids in SAM-P was about 34% and 41%, respectively, greater than in SAM-R, whereas the cell number in 40-week-old SAM-P was about 34% less than SAM-R. These results indicate that testicular maturation begins at an earlier age in SAM-P than SAM-R. Furthermore, at the age of 40 weeks signs of testicular deterioration are evident in SAM-P mice only 相似文献
925.
E. Ottaviani A. Franchini P. Fontanili 《Cellular and molecular life sciences : CMLS》1994,50(9):857-859
The effect of corticotropin-releasing factor (CRF) and pro-opiomelanocortin (POMC)-derived peptides on hemocyte phagocytosis in two molluscs,Planorbarius corneus andViviparus ater was studied. The peptides and related fragments examined are those which have been shown to influence hemocyte motility in the two species. The results obtained revealed that the effects on phagocytosis are not directly correlated with previous findings on cell motility. Furthermore, the mode of action of an individual peptide could be species-specific and dose-dependent. The relationships between peptides, locomotion and phagocytosis in these molluscs are discussed. 相似文献
926.
M. L. Mousavi Gargari R. C. Bansal K. Singh A. Mahmood 《Cellular and molecular life sciences : CMLS》1994,50(9):833-836
10 mM isatin (2,3-dioxoindole) inhibited glucose influx into human erythrocytes by over 30%. The inhibition is of the competitive type, where the affinity constant (Kt) was increased from 5.71 (control) to 11.11 mM in the presence of isatin with no change in Vmax (130 nmol/min/ml packed cells). The observed inhibition of sugar transport by isatin was not mediated through membrane–SH groups accessible to iodoacetate, iodoacetamide, DTNB, DNP or sodium arsenite. Isatin inhibited sugar transport in the presence of 2 mM harmaline, an alkaloid inhibitor of Na+, K+–ATPase activity. The inhibition was non additive which suggests that these two compounds interact with the same or a similar site on the erythrocyte membrane. 相似文献
927.
罗廷和 《武汉科技大学学报(自然科学版)》1995,(2)
还原合金化,即当炼钢或铸造过程需要进行合金化时,不用添加铁合金,而是直接添加所需合金元素的氧化物,通过还原使其合金化。研究结果表明:在等离子体条件下,30min内可以达到合锰目标值为12%~18%的还原合金化。这一新的冶炼工艺特有可能从根本上改变铁合金的生产现状. 相似文献
928.
929.
930.
Calcium/calmodulin-dependent protein kinase II increases glutamate and noradrenaline release from synaptosomes 总被引:28,自引:0,他引:28
A variety of evidence indicates that calcium-dependent protein phosphorylation modulates the release of neurotransmitter from nerve terminals. For instance, the injection of rat calcium/calmodulin-dependent protein kinase II (Ca2+/CaM-dependent PK II) into the preterminal digit of the squid giant synapse leads to an increase in the release of a so-far unidentified neurotransmitter induced by presynaptic depolarization. But until now, it has not been demonstrated that Ca2+/CaM-dependent PK II can also regulate neurotransmitter release in the vertebrate nervous system. Here we report that the introduction of Ca2+/CaM-dependent PK II, autoactivated by thiophosphorylation, into rat brain synaptosomes (isolated nerve terminals) increases the initial rate of induced release of two neurotransmitters, glutamate and noradrenaline. We also show that introduction of a selective peptidergic inhibitor of Ca2+/CaM-dependent PK II inhibits the initial rate of induced glutamate release. These results support the hypothesis that activation of Ca2+/CaM-dependent PK II in the nerve terminal removes a constraint on neurotransmitter release. 相似文献