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61.
Masayuki Nakamichi Shinji Imakawa Yasuo Kojima Ayuko Natsume 《Primates; journal of primatology》1992,33(3):413-418
Parturition behavior of a multiparous female and her interactions with group members throughout the birth process were recorded
for a free-ranging Japanese monkey (Macaca fuscata). The female showed evidence of 18 contractions during the 35 min prior to delivery, with a mean duration and a mean intercontraction
interval of 30 sec and 96 sec, respectively. These values were similar to those in individually caged Japanese monkeys. Some
adult females remained in proximity to the female who was giving birth during the prepartum phase, and her 2-year-old daughter
watched the delivery of the infant. Even during the prepartum phase the female moved in order to keep up with the group which
traveled from the feeding site to a sleeping site in the forest. 相似文献
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Hydrogen exchange kinetics of nucleic acids: Double and triple helices with Hoogsteen-type basepairs
Yuzuru Hayashi Mamoru Nakanishi Masamichi Tsuboi Toshikazu Fukui Morio Ikehara Ichiro Tazawa Yasuo Inoue 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1982,698(1):93-99
The kinetics of hydrogen-tritium exchange reaction have been followed by a Sephadex technique of a double-helical poly(ribo-2-methylthio-adenylic acid)·poly(ribouridylic acid) complex with the Hoogsteen-type basepair. Only one hydrogen in every 2-methylthio-adenine·uracil basepair has been found to exchange at a measurably slow rate, 0.023 s?1 (at 0°C), which is, however, much greater than that for a double-helix with the Watson-Crick type A·U pair. The kinetics of hydrogen-tritium exchange were also examined by triple-helical poly(rU)·poly(rA)·poly(rU) which involves both the Watson-Crick and Hoogsteen basepairings. Here, three hydrogens in every U·A·U base triplet have been found to exchange at a relatively slow rate, 0.0116 s?1 (at 0°C). The kinetics of hydrogen-deuterium exchange reactions of these polynucleotide helices have also been followed by a stopped-flow ultraviolet absorption spectrophotometry at various temperatures. On the basis of these experimental results, the mechanism of the hydrogen exchange reactions in these helical polynucleotides was discussed. In the triple helix, the rate-determining process of the slow exchange of the three (one uracil-imide and two adenine-amino) hydrogens is considered to be the opening of the Watson-Crick part of the U·A·U triplet. This opening is considered to take place only after the opening of the Hoogsteen part of the triplet. 相似文献
64.
Toshio Nakatani Kazue Ozawa Motokazu Asano Minoru Ukikusa Yasuo Kamiyama Takayoshi Tobe 《Life sciences》1981,28(3):257-264
The changes in the energy substrate utilized by the remnant liver were studied in relation to the changes in the cellular energy status of 25 and 70% hepatectomized rabbits. In 25% hepatectomized rabbits, the energy charge level of the remnant liver remained unchanged, the energy substrate of which was predominantly glucose, rather than fatty acid. In contrast, in 70% hepatectomized rabbits, the energy production by the mitochondria was mainly dependent upon fatty acid oxidation at the early period after hepatectomy when the energy charge level decreased remarkably, and then upon glucose oxidation, concomitant with the restoration of the energy charge. It is suggested that the changes in the energy substrate utilized are closely related to those in the energy charge level and the mitochondrial phosphorylative activity of the remnant liver following hepatectomy. 相似文献
65.
Photosynthetic activities of the thylakoid membranes modifiedwith pyridoxal phosphate (PLP) and sodium borohydride in lightwere studied and compared with those modified in the dark. PLPmodified the membrane-bound chloroplast coupling factor 1 (CF1)and inhibited photophosphorylation. Only PLP modification inlight stimulated basal electron transport. This stimulationof electron transport was prevented by the presence of ATP orcarbonylcyanide m-chlorophenylhydrazone in the modificationmixture. Magnesium ion was required for PLP modification. Theextent of lightinduced proton uptake was decreased by PLP modificationin light. N,N'-Dicyclohexylcarbodiimide lowered the stimulatedelectron transport to the basal level of unmodified chloroplastsand restored proton uptake. When chloroplasts were modified with 4 mM PLP in light and dark,11.6 and 11.0 mol of PLP were incorporated into mol of CF1,respectively. ATP could bind with high affinity to CF1 isolatedafter PLP modification in light. The results indicate that PLP modifies membrane-bound CF1 whichhas a conformation altered by energization of the thylakoidsin light, and causes an apparent uncoupling of phosphorylation(stimulation of basal electron transport). The results suggestthat this uncoupling is induced by the loss of the regulatoryfunction of CF1 for proton translocation after PLP modificationin light.
1 Presented at the ISRACON on Control Mechanisms in Photosynthesis.Aug. 31-Sept. 4, 1980, Acre, Israel (Received June 22, 1981; Accepted August 28, 1981) 相似文献
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Summary Ceramide is the fundamental structure and key intermediate of all sphingolipids. Biosynthesis and catabolism of brain ceramide, especially their relationship to the metabolism of more complex sphingolipids in brain, are reviewed. Human genetic diseases which involve altered ceramide metabolism are also discussed. 相似文献
69.
Yasuo Kishimoto Hiroshi Akanuma Inderjit Singh 《Molecular and cellular biochemistry》1979,28(1-3):93-105
Summary -Hydroxylation is an enzymatic reaction by which long-chain fatty acids are converted to their -hydroxy derivatives. This reaction, in animals, can be detected only in developing brain and is the rate-determining step in the synthesis of hydroxycerebroside, which is an indispensable and abundant myelin lipid. In addition to a particulate fraction from brain, two cytoplasmic factors, one heat-stable and the other heat-labile, are required for -hydroxylation. During the past eight years we have been investigating -hydroxylation. Our progress is summarized and discussed here. 相似文献
70.
The regulation by adenylates of activities of various partial electron transport systems in spinach chloroplasts was studied using systems from H2O to 2,5-dimethyl-p-benzoquinone, H2O to 2,6-dichlorophenolindophenol, reduced 2,6-dichlorophenolindophenol to methyl viologen, and H2O to methyl viologen or ferricyanide. Adenylates regulated all of them. The ratio of the amount of esterified Pi (P) to that of electrons transported (e) in coupling with phosphorylation manifested that there are two phosphorylation sites: one between H2O and 2,5-dimethyl-p-benzoquinone or 2,6-dichlorophenolindophenol and another between reduced 2,6-dichlorophenolindophenol and methyl viologen, under the proposed stoichiometries,i.e., P/H+=0.5 and H+/e=1, where H+ is the amount of protons pumped by electron transport (= those translocated during phosphorylation), when the basal electron transport (the part not regulated by adenylates) was excluded. The effects of pH, phlorizin, and methylamine on the adenylate regulation of electron transport, and the stimulation profile of electron transport coupled with quasiarsenylation suggested no distinction between the two phosphorylation sites. 相似文献