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SHIGEKO SUZUKI-MORIMOTO YOSHIHIRO YAMAMOTO TAKEO YAMAGUCHI 《Development, growth & differentiation》1985,27(6):729-736
Hydrocortisone is regarded as an initiator of keratinization in embryonic skin. The present investigation dealt with the effect of hydrocortisone on the proliferation of epidermal cells during early development: Cell kinetic analyses using 3 H-thymidine autoradiography were applied to a skin organ culture prepared from a 13-day chick embryo.
Hydrocortisone at a concentration between 0.01 and 1.0 μg/ml was effective in initiating a morphological change leading to the epidermal keratinization in vitro and caused a marked decrease in the mitotic and labeling indices of epidermal basal cells, the decrease being maximum at 2 days of culture previous to the morphological change.
During continuous labeling with3 H-thymidine, the number of labeled basal cells reached 100% within 2 days in the control and 4 days in the culture treated with hydrocortisone. This confirmed that the growth fraction of epidermal basal cells was 1.0 even after the administration of hydrocortisone.
The duration of each cell cycle phase at 2 days of culture was determined by percent labeled mitoses and double-labeling analyses. It was concluded that hydrocortisone extended the generation time of epidermal basal cells at this time point about three fold over the control. This extension was mainly due to the elongation of the G1 phase. 相似文献
Hydrocortisone at a concentration between 0.01 and 1.0 μg/ml was effective in initiating a morphological change leading to the epidermal keratinization in vitro and caused a marked decrease in the mitotic and labeling indices of epidermal basal cells, the decrease being maximum at 2 days of culture previous to the morphological change.
During continuous labeling with
The duration of each cell cycle phase at 2 days of culture was determined by percent labeled mitoses and double-labeling analyses. It was concluded that hydrocortisone extended the generation time of epidermal basal cells at this time point about three fold over the control. This extension was mainly due to the elongation of the G
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Macrophage Migration Inhibition by Serum from Desensitized Animals Previously Sensitized with Tubercle Bacilli 总被引:4,自引:0,他引:4
MIGRATION of peritoneal exudate cells removed from guinea-pigs or mice exhibiting delayed hypersensitivity is inhibited by specific antigen1–3. This in vitro macrophage migration inhibition has been regarded as a useful immunological test for delayed skin hypersensitivity4,5. Studies of the mechanism of this phenomenon revealed that, in contact with specific antigen, lymphocytes from sensitized animals released into the medium a specific substance (migration inhibitory factor; MIF) capable of inhibiting the migration of normal macrophages6,7. When injected intradermally into normal guinea-pigs, MIF elicits inflammatory reactions characterized by induration, erythema and mononuclear cell infiltration8. 相似文献
4.
Artificial induction of functional sex-reversal in genotypic females of the medaka (Oryzias latipes) 总被引:8,自引:0,他引:8
YAMAMOTO T 《The Journal of experimental zoology》1958,137(2):227-263
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In an attempt to explain the influence of gravity on the behaviour of ageotropic plant organs, a pea mutant (Pisum sativum ageotropum) and normal pea (Pisum sativum cv. Sabel) were examined. The mutant has a significantly lower germination rate (large seeds: 25%, small seeds: 10%) than normal pea seeds (55%). Removal of testa increased germination dramatically, the values obtained were 63 and 89%, respectively. Immediately after imbibition the mutant from which the testa had been removed, developed more slowly than normal pea seeds; after 28 h the difference in elongation rate between the two types was reversed. When continuously stimulated geotropically in the horizontal position the elongation in the mutant is larger than in the normal pea roots kept in the same position. During a 24 h period starting 48 h after imbibition the mutant root elongated 45.0 mm while the value for the normal pea root was 11.5 mm. The course of the geotropic curvature in roots of the two types has been followed during a period of 24 h. Normal pea roots develop an asymmetry in the extreme root tip region after 30 min of horizontal stimulation. After prolonged stimulation (exceeding 2 h) the asymmetry has disappeared and the curvature distributed over the entire growth region. When roots of normal pea are stimulated continuously at various angles, the optimum angle of geotropic response is 90° with decreasing responses in the order 135° (i.e. the root tip is pointing obliquely upward) and 45°. The presumed ageotropic behaviour of the mutant has only to a certain extent been confirmed in the present study. When stimulated at 135° a slight positive curvature developed; stimulation at 90° and 45° gave a slight negative curvature. 相似文献
8.
NORIKO KAWAMOTO YAMAMOTO 《Development, growth & differentiation》1975,17(3):253-263
The effects of hypophysectomy on spermatogenesis in testes implanted to neuter individuals of the medaka, oryzias latipes , have been histologically studied.
The neuter fish produced by prolonged androgen treatment during larval life maintained the implanted testes for more than 8 months, irrespective of the genetic sex of the host. Histological examination revealed that all the implanted testes were filled with numerous cysts containing cells at all spermatogenetic stages, as in the normal testes. Each cyst contained only cells at the same stage. Furthermore, the implanted testes had fertile spermatozoa. In the experiment of regeneration of amputated anal fins, the implanted testes were found to be able to induce the formation of papillar processes, although the number of processes was one-half of that induced by normal testes.
Hypophysectomy of the fish was successfully achieved by orbital approach. The survival rate of the operated fish was 95% a week after the operation and still 50% 14 months later. Hypophysectomy inhibited the transformation of spermatogonia to spermatocytes in spermatogenesis.
The presence of the capacity to carry out normal spermatogenesis and induce papillar processes in the testis-implanted neuter fish suggests that the hypothalamus of the neuter fish was not seriously affected by prolonged androgen treatment. 相似文献
The neuter fish produced by prolonged androgen treatment during larval life maintained the implanted testes for more than 8 months, irrespective of the genetic sex of the host. Histological examination revealed that all the implanted testes were filled with numerous cysts containing cells at all spermatogenetic stages, as in the normal testes. Each cyst contained only cells at the same stage. Furthermore, the implanted testes had fertile spermatozoa. In the experiment of regeneration of amputated anal fins, the implanted testes were found to be able to induce the formation of papillar processes, although the number of processes was one-half of that induced by normal testes.
Hypophysectomy of the fish was successfully achieved by orbital approach. The survival rate of the operated fish was 95% a week after the operation and still 50% 14 months later. Hypophysectomy inhibited the transformation of spermatogonia to spermatocytes in spermatogenesis.
The presence of the capacity to carry out normal spermatogenesis and induce papillar processes in the testis-implanted neuter fish suggests that the hypothalamus of the neuter fish was not seriously affected by prolonged androgen treatment. 相似文献
9.
Screening test on anti-oxidation activity using 1,1-diphenyl-2-picrylhydrazyl(DPPH) was performed for 99 ethanol extracts of 85 species of natural thalli of lichens in order to find novel anti-oxidation compounds.The 17 extracts of natural thalli showed high anti-oxidation activity.Among them,the activities of extracts from Hypogymnia vittata,Peltigera aphthosa,Nephromopsis ornata,Pseudevernia furfuracea,Cladonia vulcani and Peltigera elizabethae were higher.Extracts of Peltigera spp.showed higher activity than those of other genera.The ethanol extract of P.aphthosa had been separated into ethyl acetate-soluble and water-soluble fractions.Two anti-oxidative spots were found only in the water-soluble fractions by thin-layer chromatography.The compound in the lower spot had the same Rf value,UV spectrum,and color as authentic solorinine that was previously found as a unique quaternary ammonium compound from Peltigera spp.We now report that the hydrophilic lichen substance,solorinine showed a nearly same anti-oxidation activity(EC50=120?mol/Lol/L) as standard antioxidant Trolox(EC50=150?mol/L). 相似文献
10.
谭翠燕 徐春和 沈均人 SAKUMA Shinsuke YAMAMOTO Yasushi BALNY Claude 阮康成 《Acta biochimica et biophysica Sinica》2003,(7)
利用荧光光谱学等方法结合高压力技术研究了光合作用系统II中的一个外周蛋白——— 2 3kD(以P2 3k表示 )蛋白的去折叠。热力学研究表明 ,在 2 0℃、180MPa(1MPa =10 .0大气压 )可使该蛋白质完全去折叠 ,而在3℃ ,16 0MPa即可使该蛋白质完全去折叠 ,这是迄今为止有关研究中最易被高压力去折叠的一个蛋白质。在2 0℃ ,该蛋白质在常压下去折叠反应的标准自由能与标准体积变化分别为 2 3.4 5kJ mol和 - 15 0 .3ml mol;动力学研究揭示该蛋白质的折叠反应的活化体积ΔV f 为正值 (84 .1ml mol) ,而去折叠反应的活化体积ΔV u 为负值(- 6 6 .2ml mol)。在常压下 ,折叠和去折叠反应的速度常数 (K0f,K0u)分别为 1.87s- 1 和 1.3× 10 - 4s- 1 ,这些结果为解释该蛋白质易被压力去折叠提供了线索 相似文献