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11.
The dc conductivity of polycrystalline phosphatidylethanolamine (PE) was measured in the temperature range 60–120°C. Since no conclusive evidence had so far been obtained for the presence of proton conduction in this phospholipid, hydrogen gas was shown in the present experiment to evolve during the electrolysis in its premelted state between 91 and 124°C. In this temperature range molecules assume rotation around the molecular axes and proton conduction of the Grotthus type takes place possibly along two chains of intermolecular hydrogen bonds running in parallel. Zwitter-ions behave cooperatively as proton donors and acceptors in transferring proton from molecule to molecule via the hydrogen bond networks. This efficient push-pull way of proton transferring seems to account for the fact that no polarization was observed in the dc conduction experiments. The amount of evolved gas appears to be not exactly in accordance with Faraday's law and discussions are made on possible causes for this slight deviation. 相似文献
12.
The effects of substance P and met5-enkephalin in dog ileum 总被引:1,自引:0,他引:1
E E Daniel T Gonda T Domoto M Oki 《Canadian journal of physiology and pharmacology》1982,60(6):830-840
Substance P initiated tonic contraction of dog ileum when administered in doses from 1 pg to 20 micrograms intraarterially (ED50 = 67 ng). Low doses acted to excite cholinergic postganglionic neurones since atropine or tetrodotoxin (TTX) increased the ED50 of substance P about 25-fold, while hexamethonium and local field stimulation had only a small effect to increase the ED50. Also atropine and tetrodotoxin effects were not additive. Higher doses apparently acted to stimulate smooth muscle directly, but no evidence was obtained that local field stimulation could release substance P to act on smooth muscle. Substance P tachyphylaxis prevented substance P actions on cholinergic nerves, but it did not affect responses to intraaterial acetylcholine or block distal inhibition from proximal distention or field stimulation. Met-enkephalin given intraarterially, was also excitatory in doses from 1 ng to 20 micrograms; the amplitude of tonic and phasic contractions produced was significantly decreased by TTX and atropine but was not diminished by hexamethonium or substance P tachyphylaxis. Partial tachyphylaxis to met-enkephalin was produced but was not diminished by hexamethonium or substance P tachyphylaxis. Partial tachyphylaxis to met-enkephalin was produced without affecting the ED50 for substance P. We conclude that substance P acts in small amounts on receptors in myenteric nerves to release acetylcholine by a mechanism, presumably involving postganglionic cholinergic nerves, while met-enkephalin also apparently may act at least in part through a similar TTX- and atropine-sensitive mechanism. These peptides also caused activation of other receptors, probably on smooth muscle by noncholinergic. TTX-insensitive mechanisms. Also the receptors for each peptide which are located on nerves were distinct and independent since tachyphylaxis could be produced to each without affecting the response to the other. 相似文献
13.
The effect of implantation of Ehrlich ascites tumor (EAT) cells of creatine distribution was investigated. It was also studied how depletion of creatine by feeding creatine-analogue β-guanidinopropionic acid (β-GPA) affects the growth of EAT cells in mice. Enhanced mobilization of creatine from host tissues to EAT cells against a greater concentration gradient was observed. The creatine (but not creatinine) level in blood plasma was lowered to 22% of the normal value by β-GPA feeding alone and assimilation of 14C-creatine into EAT cells was inhibited. The growth of EAT cells was significantly reduced and the duration of survival of mice after implantation of EAT cells was extended when the creatine concentration was decreased. A decrease in daily food consumption and the degree of muscle atrophy after implantation of EAT cells was less in β-GPA than control groups. In the creatine-depleted mice, the rate of increase in total EAT cell number and the volume of abdominal ascites were approximately half of the control values, and more dead EAT cells were observed. These results suggest that supplementation of β-GPA inhibits creatine transfer to EAT cells and reduces the growth of cancer cells. 相似文献
14.
R G Ramsay M A Thompson J A Hayman G Reid T J Gonda R H Whitehead 《Cell growth & differentiation》1992,3(10):723-730
Expression of the protooncogene c-Myb protein was assessed in normal mucosa and in tumor samples resected from six patients. We found that the tumor samples always expressed higher levels of full length Myb protein than the normal tissue. This contrasts with the situation in c-myb-associated hemopoietic malignancies of the mouse and chicken, in which Myb proteins are generally amino or carboxyl truncated. Tissues from five patients with colonic adenomatous polyps were also examined and found to express levels of Myb that were, in general, intermediate between those found in normal tissues and tumors. Of particular interest is that the more dysplastic polyps displayed higher Myb levels. In one patient with carcinoma and multiple colonic polyps, some polyps had intermediate levels of Myb, whereas one polyp with carcinoma in situ expressed tumor-like levels of Myb. To directly test the hypothesis that Myb expression may be important in determining the rate of colonic cell proliferation, we examined three colonic carcinoma cell lines and one polyp cell line. We found that the cell lines with the most rapid doubling times exhibited the highest Myb levels. In addition, we show that antisense myb oligonucleotides retard the proliferation of one of these colonic cell lines which expresses the highest level of Myb. 相似文献
15.
Nucleotide sequence of the gene coding for four subunits of cytochrome c oxidase from the thermophilic bacterium PS3 总被引:7,自引:0,他引:7
M Ishizuka K Machida S Shimada A Mogi T Tsuchiya T Ohmori Y Souma M Gonda N Sone 《Journal of biochemistry》1990,108(5):866-873
The gene coding for four subunits of cytochrome aa3-type oxidase was isolated from a genomic DNA library of the thermophilic bacterium PS3 and sequenced. The N-terminus of each subunit was also sequenced to verify the initiation site of the reading frame. The deduced amino acid sequences contained 615 amino acid residues for subunit I (CO1/caaB product), 333 residues for subunit II (CO2/caaA product), 207 residues for subunit III (CO3/caaC product), and 109 residues for subunit IV (CO4/caaD product) after processing. Re-examination of the sequencing of caa revealed a longer open reading frame for CO1, which contains 14 transmembrane segments instead of 12 [Sone et al. (1988) J. Biochem. 103, 606-610], although the main portions of the sequences constituting cytochrome a (FeA), cytochrome a3 (FeB), and CuB are correct. PS3 CO2 has an additional sequence for cytochrome c after the CuA binding protein portion with 2 transmembrane segments, which is homologous to the mitochondrial counterpart. PS3 CO3 has DCCD-binding glutamyl residues but contains only 5 transmembrane segments, unlike the mitochondrial counterpart, which has 7 segments. The subunits of PS3 cytochrome oxidase (aa3-type) show clear similarity in amino acid sequences with those of cytochrome bo-type oxidase from Escherichia coli as well, in spite of the difference of hemes. PS3 CO3 and CO4 are much more similar to E. coli CO3 and CO4 than to mitochondrial CO3 and CO4, respectively. 相似文献
16.
A main acidic polysaccharide preparation was isolated from the leaves of Malva sylvestris L. var mauritiana Mill. It is composed of L-rhamnose, D-galactose, D-galacturonic acid, and D-glucuronic acid in the molar ratio of 22:6:22:11, and it contains 7.7% peptide. It was homogeneous by electrophoresis and gel chromatography, which gave a value of 11,000 as molecular weight. The structure of the polysaccharide component was elucidated by methylation analysis and partial hydrolysis. The substance showed considerable anticomplementary activity. 相似文献
17.
Avian Retroviruses That Cause Carcinoma and Leukemia: Identification of Nucleotide Sequences Associated with Pathogenicity 总被引:11,自引:7,他引:4
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Diana Sheiness Klaus Bister Carlo Moscovici Lois Fanshier Thomas Gonda J. Michael Bishop 《Journal of virology》1980,33(3):962-968
Avian myelocytomatosis virus (MC29V) is a retrovirus that transforms both fibroblasts and macrophages in culture and induces myelocytomatosis, carcinomas, and sarcomas in birds. Previous work identified a sequence of about 1,500 nucleotides (here denoted oncMCV) that apparently derived from a normal cellular sequence and that may encode the oncogenic capacity of MC29V. In an effort to further implicate oncMCV in tumorigenesis, we used molecular hybridization to examine the distribution of nucleotide sequences related to oncMCV among the genomes of various avian retroviruses. In addition, we characterized further the genetic composition of the remainder of the MC29V genome. Our work exploited the availability of radioactive DNAs (cDNA's) complementary to oncMCV (cDNAMCV) or to specific portions of the genome of avian sarcoma virus (ASV). We showed that genomic RNAs of avian erythroblastosis virus (AEV) and avian myeloblastosis virus (AMV) could not hybridize appreciably with cDNAMCV. By contrast, cDNAMCV hybridized extensively (about 75%) and with essentially complete fidelity to the genome of Mill Hill 2 virus (MH2V), whose pathogenicity is very similar to that of MC29V, but different from that of AEV or AMV. Hybridization with the ASV cDNA's demonstrated that the MC29V genome includes about half of the ASV envelope protein gene and that the remainder of the MC29V genome is closely related to nucleotide sequences that are shared among the genomes of many avian leukosis and sarcoma viruses. We conclude that oncMCV probably specifies the unique set of pathogenicities displayed by MC29V and MH2V, whereas the oncogenic potentials of AEV and AMV are presumably encoded by a distinct nucleotide sequence unrelated to oncMCV. The genomes of ASV, MC29V, and other avian oncoviruses thus share a set of common sequences, but apparently owe their various oncogenic potentials to unrelated transforming genes. 相似文献
18.
Jin Hao Kim Hak Sung Yu Seung Taek Shin Sae Ron Lee Sung Hee Seo Geom Seog 《Molecular biology reports》2021,48(2):1171-1180
Molecular Biology Reports - A large body of research has demonstrated a synergistic anticancer effect between docosahexaenoic acid (DHA) and standard chemotherapy regimens against colorectal cancer... 相似文献
19.
Tae-Sung Kwon Young Kyu Park Joo-Hoon Lim Sae Han Ryou Cheol Min Lee 《Journal of Asia》2013,16(3):321-328
Forest fires are one of the most frequent and important causes of forest disturbances, the occurrence of which is globally increasing due to the effects of climate change. This study aimed to determine the impacts of fire and human activity on arthropod communities in affected forests. Twelve study sites in three burned areas were selected for this study. Intensities of disturbance in the study sites were characterized as follows: Disturbance Degree (DD) 0 (no fire), DD 1 (surface fire), DD 2 (crown fire), and DD 3 (crown fire followed by reforestation). Arthropods were collected using pitfall traps. Fourteen arthropod taxa (families, orders or classes), which are relatively homogeneous in their feeding habits and abundant, were analyzed. Depth of litter layer was selected as an environmental indicator for disturbance intensity, as it decreases linearly as the degree of disturbance increased. Changes of arthropod abundance in response to disturbance differed among functional guilds. As disturbance intensity increased, the abundance of detritivores decreased, but the abundance of herbivores increased. However, the abundance of predators varied between taxa. Formicidae and Araneae increased in disturbed sites, whereas Carabidae and Staphylinidae did not change. The abundance of Thysanura and Diptera was highly correlated with disturbance intensity, and may be suitable as a bioindicator for forest disturbance. Arthropod communities were more heterogeneous in forests of intermediate disturbance. 相似文献
20.
Hye Jin Yoo Soon Young Hwang Ho Cheol Hong Hae Yoon Choi Sae Jeong Yang Dong Seop Choi Sei Hyun Baik Matthias Blüher Byung-Soo Youn Kyung Mook Choi 《PloS one》2013,8(2)