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1.
T Ikeda T Yoshida Y Ito I Murakami O Mokuda M Tominaga H Mashiba 《Archives of biochemistry and biophysics》1987,257(1):140-143
To elucidate the physiological significance of ketone bodies on insulin and glucagon secretion, the direct effects of beta-hydroxybutyrate (BOHB) and acetoacetate (AcAc) infusion on insulin and glucagon release from perfused rat pancreas were investigated. The BOHB or AcAc was administered at concentrations of 10, 1, or 0.1 mM for 30 min at 4.0 ml/min. High-concentration infusions of BOHB and AcAc (10 mM) produced significant increases in insulin release in the presence of 4.4 mM glucose, but low-concentration infusions of BOHB and AcAc (1 and 0.1 mM) caused no significant changes in insulin secretion from perfused rat pancreas. BOHB (10, 1, and 0.1 mM) and AcAc (10 and 1 mM) infusion significantly inhibited glucagon secretion from perfused rat pancreas. These results suggest that physiological concentrations of ketone bodies have no direct effect on insulin release but have a direct inhibitory effect on glucagon secretion from perfused rat pancreas. 相似文献
2.
Dynamic light-scattering measurements were carried out for collagen in acetate buffer (pH 4.8) extracted from lathyritic ratskin. The correlation functions were analyzed in terms of the semiflexibility of collagen molecules. The experimental Γ /K2 vs K2 relationship was compared with the theoretical one based on formulation including anisotropy in translational diffusion, chain flexibility, and the hydrodynamic interaction; Γ is the average decay rate and K is the magnitude of the momentum transfer vector. By using the model parameters evaluated from the Γ /K2 vs K2 relationship, a good agreement was obtained between profiles of theoretical and experimental correlation functions over the entire delay times. Detailed examinations of the dynamic light-scattering spectrum permitted us to conclude that a set of the contour length L of 300 nm and the Kuhn length γ?1 of 340 nm are much more probable than other sets of L and γ?1 that equally explain static quantities such as the radius of gyration. The results show that collagen molecules are well characterized by a wormlike chain model. 相似文献
3.
Dr. Emiko Matsumoto Kazushige Hirosawa Kiyoshi Takagawa Yoshiki Hotta 《Cell and tissue research》1988,252(2):293-300
Summary A Drosophila visual mutant rdgA has photoreceptive cells which degenerate gradually after eclosion. Fine structure of the retinular cells of rdgA
KS60
and rdgA
K014
was studied during early stages of degeneration to determine the initial morphological defects. The retinular cells of these two alleles showed the following structural abnormality within 1 day after eclosion: (1) rhabdomeres were small and irregular in shape; (2) cisternae of the rough endoplasmic reticulum were more numerous than those in normal retinular cells; (3) submicrovillar cisternae were absent; and (4) lysosomes were fewer than normal. Three-dimensional reconstruction of serial sections of the ommatidia showed that the degeneration of mutant rhabdomeres proceeds more rapidly in regions remote from the nuclei. These results suggest that the process of turnover of rhabdomeric microvilli is abnormal in rdgA. We also confirmed an increase of lysosomes and destruction of cellular organelles, as reported by previous investigators at more advanced stages of degeneration. 相似文献
4.
T Ikeda T Takeuchi M Honda O Mokuda M Tominaga H Mashiba 《Biochemical medicine and metabolic biology》1988,40(3):276-281
To evaluate the possible role of somatomedin-C, insulin-like growth factor I, in renal hypertrophy in early diabetes, kidney tissue SmC concentrations were measured in streptozotocin-induced (80 mg/kg ip) diabetic rats. Body weight, liver weight, plasma SmC concentration, and SmC concentration in the liver of diabetic rats were significantly lower than those of controls. Seven days after induction of diabetes, the kidney weight (898 +/- 95 mg) in diabetic rats was significantly greater than that in controls (755 +/- 69 mg), while SmC concentration in the kidney of diabetic rats (1.7 +/- 0.3 U/g kidney) was significantly lower than that of control rats (5.4 +/- 0.6 U/g kidney). These results suggest that renal SmC may not have an important role in renal hypertrophy in early stages of diabetes and that renal production of SmC may be impaired by insulin deficiency in rats. 相似文献
5.
Tazawa Masashi; Kurosawa Sachiko; Amino Shin-ichi; Tominaga Yoshito; Sakano Katsuhiro; Matsumoto Tomotaka 《Plant & cell physiology》1991,32(2):253-260
Rotational cytoplasmic streaming in leaves of Egeria densa wasinduced by light as well as by L-histidine (L-His). During bothtreatement with light and with L-His chloroplasts on the periclinalface were dislodged and moved to the anticlinal face where rotationalcytoplasmic streaming occurred. The effective concentrationof L-His was about 0.01 mM and the effect was almost saturatedat 0.1 mM. A derivative of L-His, 3-methyl-L-histidine, wasslightly less effective than L-His. By contrast, 1-methyl-L-histidinewas almost ineffective for induction of streaming, not onlyin Egeria but also in Vallisneria. Our resutlts are in markedcontrast to Fitting's result (1936) that 1-M-L-His is more effectivethan L-His. In Egeria, 1-methyl-L-His counteracted the stimulativeeffect of L-His. 1-Methyl-L-His penetrated into leaf cells ofEgeria to the same extent as 3-methyl-L-His and to a greaterextent than L-His. This observation excludes the possibilitythat the impermeability of leaves to 1-M-L-His might be responsiblefor its ineffectiveness. 1-M-L-His did not interfere with photodinesis.Differences in the mechanism of induction of rotational streamingby L-His and by light are discussed.
4 Present address: Fukui Institute of Technology, Gakuen, Fukui,910 Japan (Received July 16, 1990; Accepted December 20, 1990) 相似文献
6.
Tominaga Yoshito; Kuchitsu Kazuyuki; Katsuhara Maki; Tazawa Masashi; Miyachi Shigetoh 《Plant & cell physiology》1991,32(2):261-268
Rotational streaming of the cytoplasm including chloroplastswas induced by L-histidine, as well as by light, on the anticlinalface of leaf cells of Egeria densa. In the case of treatmentwith L-histidine some of the chloroplasts remained stationaryon the periclinal face of cells after rotational cytoplasmicstreaming was initiated. However, these chloroplasts were easilydislodged and translocated to the centrifugal end of the histidine-treatedcells by application of a centrifugal force that barely affectedthe location of chloroplasts in cells incubated in the darkwithout L-histidine. This result indicates that the anchoringof chloroplasts was weakened by L-histidine. Thus only the releaseof chloroplasts from anchoring was not enough for initiationof their streaming. The cytoplasmic pH (pHc) and vacuolar pH(pHv) were noninvasively monitored by in vivo 31P-nuclear magneticresonance (NMR) spectroscopy. Compared with the dark controlvalue, both illumination and treatment with L-histidine increasedthe pHc by 0.3 units. In contrast, pHv changed only a littlewith both illumination and treatment with L-histidine. Releaseof chloroplasts from anchoring and initiation of cytoplasmicstreaming are discussed in relation to the increase in pHc inducedby both light and L-histidine.
4 Present address: Department of Cell Biology, National Instituteof Agrobiological Resources, Kannondai, Tsukuba, Ibaraki, 305Japan
5 Present address: Marine Biotechnology Institute Co., Ltd.,Head Office, 2-35-10 Hongo, Bunkyo-ku, Tokyo, 113 Japan (Received July 16, 1990; Accepted December 20, 1990) 相似文献
7.
Summary The photoreceptors in the compound eye of a cabbage butterfly, Pieris rapae, were examined by conventional and intracellular-labeling electron microscopy by the use of the cobalt(III)-lysine complex as an ionized marker. Five types of spectral sensitivity were recorded intracellularly in electrophysiological experiments. They peaked at about 340, 380, 480, 560 and 620 nm, respectively. One of the distal retinula cells (R2) was a UV receptor, whereas the R4 distal retinula cell was a green receptor. The basal retinula cell, R9, was found to be a red receptor; it was localized near the basement membrane, having a bilobed cell body with an individual nucleus in each lobe. A small number of rhabdomere microvilli were present in a narrow cytoplasmic bridge connecting the two lobes. The axons of six retinula cells (R3–R8) in each ommatidium terminated at the cartridge in the lamina (short visual fiber), whereas those of the other three retinula cells, R1, R2 and R9, extended to the medulla (long visual fiber). The information from the UV and red receptors is therefore probably delivered directly to the medulla neurons, independent of that from the other spectral receptor types. 相似文献
8.
A species of Daphnia, Daphnia curvirostris Eylmann, found in high mountain lakes and ponds in central Japan is described. Although there were some differences in the shape of the male rostrum and the chromosome number between European populations as described by Johnson (1952) and Trentini (1980), and Japanese ones collected from high mountain waters, Japanese specimens had many characteristics similar to the taxon D. curvirostris of Europe. 相似文献
9.
Purple membrane from Halobacterium halobium in suspensions has been studied by quasielastic light scattering. The intensity correlation functions of polarized scattered light were measured at various K2 values (K being the magnitude of the scattering vector), and the first cumulant Gamma of the field correlation function G1(tau) was obtained by a cumulant expansion method. The apparent diffusion coefficient Gamma /K2 did not increase monotonically with K2 values and showed a distinct anomaly in an intermediate range of K. A theoretical formulation of G1(tau) for a disc and an extremely oblate ellipsoidal shell of revolution (S. Fujime and K. Kubota, Biophys. Chem. 23 (1985) 1) was applied to the analysis of the spectra, and characteristic features of experimental spectra were well reproduced. It was suggested that a strong interference effect between scattered rays on Gamma /K2 should be attributed to a slight noncircular shape of the purple membrane and that a contribution to Gamma /K2 from membrane flexibility should be taken into account. This study will provide experimental evidence of the feasibility of membrane studies by dynamic light scattering. 相似文献
10.
A Lowy P M Flood A Tominaga J A Drebin J Dambrauskas R K Gershon M I Greene 《Journal of immunology (Baltimore, Md. : 1950)》1984,132(2):640-643
We have analyzed the first-order suppressor factor secreted by an azobenzenearsonate (ABA)-specific T suppressor cell (Ts) hybridoma. Treatment of the factor with 5 mM dithiothreitol (DTT) yields two fragments with distinct phenotypes and functional capabilities. One fragment is bound by a monoclonal anti-I-J antibody, the other is not. Further, although neither molecular fragment by itself is sufficient to suppress an ABA response, a mixture of the two reconstitutes the suppressive activity. The I-J- portion of the first-order suppressor factor (TsF1) presumably guides the antigen specificity; activity of the ABA-specific Ts I-J- TsF1 factor can be reconstituted with an I-J+ subunit of a TsF molecule of either sheep red blood cell (SRBC) or ABA specificity. The genetic restriction for Igh-linked determinants of the ABA/SRBC hybrid TsF molecules is influenced by the I-J+ portion, regardless of the original antigen specificity of that molecule. The data support a two-subunit TsF model. Polyclonal ABA-specific TsF1 molecules appear to resemble the monoclonal factor in structure. 相似文献