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1.
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
2.
Changes in total nitrogen and free amino acid contents in stemcuttings of Morus alba have been studied. The fresh and dryweights and total nitrogen amounts of the parent stems of cuttingsdecreased initially after cutting. Their increase follows theformation of main roots in cuttings, suggesting that, like carbohydrates,sugars and starch, stored nitrogenous substances are used forsprouting and rooting of cuttings. Amino acids found in stems,roots and shoots are those common in other higher plants withthe exception of pipecolic acid and 5-hydroxypipecolic acid.Significant changes in the levels of asparagine, proline, arginine,-aminobutyric acid and alanine in roots, bark and wood of parentstems were observed during cutting growth, whereas those ofother amino acids remained comparatively constant; the mostpredominant amino acid in the starting materials was proline.while that in the cuttings during growth was asparagine. Theresults suggest that, among free amino acids, asparagine, prolineand arginine play the major part in storage of nitrogen in mulberry.The importance of glut-amine and asparagine in nitrogen metabolismin mulberry has been discussed. 相似文献
3.
DISTRIBUTION OF MATURATION-PROMOTING FACTOR IN STARFISH OOCYTE STRATIFIED BY CENTRIFUGATION 总被引:1,自引:1,他引:0
TAKEO KISHIMOTO JUNKO KUBOTA HARUO KANATANI 《Development, growth & differentiation》1977,19(4):283-288
In starfish, cytoplasm taken from maturing oocytes is capable of inducing breakdown of the germinal vesicle and subsequent maturation when injected into immature oocytes. The cytoplasmic factor has been designated as "maturation-promoting factor" (MPF). Ooplasm was stratified by centrifugation of maturing oocytes in density-graded Ficoll-seawater, without disrupting the cell. Three strata were distinguished beginning with the centripetal side: oil cap, hyaline layer and yellow layer. MPF activity was shown to be localized in the hyaline layer. Electron microscopic observation revealed that the hyaline layer contains Golgi complexes, many lucent vesicles and multi-vesicular bodies as distinct organelles, but seldom contains such inclusions as the lipid droplets forming the oil cap, mitochondria, yolk and pigment granules contained in the yellow layer. Based on these observations, a possible cytoplasmic component with MPF activity is discussed. 相似文献
4.
MAKIKO NAGAI MIWA OHNISHI TAKEO UEHARA MUTSUMI YAMAGAMI EIKO MIURA MAI KAMAKURA AKIRA KITAMURA SHU‐ICHI SAKAGUCHI WATARU SAKAMOTO TERUO SHIMMEN HIDEHIRO FUKAKI ROBERT J. REID TETSURO MIMURA 《Plant, cell & environment》2013,36(10):1826-1837
The concentration of ions in plant cells and tissues is an essential factor in determining physiological function. In the present study, we established that concentration gradients of mobile ions exist in both xylem exudates and tissues within a barley (Hordeum vulgare) primary leaf. For K+ and NO3?, ion concentrations generally decreased from the leaf base to the tip in both xylem exudates and tissues. Ion gradients were also found for Pi and Cl? in the xylem. The hydathode strongly absorbed Pi and re‐translocated it to the rest of the plant, whereas Cl? was extruded. The ion concentration gradients developed early during leaf growth, increased as the tissue aged and remained under both high and low transpiration conditions. Measurement of the expression profiles of Pi, K+ and NO3? transporters along the longitudinal axis of the leaf revealed that some transporters are more expressed at the hydathode, but for most transporters, there was no significant variation along the leaf. The mechanisms by which longitudinal ion gradients develop in leaves and their physiological functions are discussed. 相似文献
5.
LIVIA ECHTERNACHT PAULO TAKEO SANO MARCELO TROVÓ JEAN‐YVES DUBUISSON 《Botanical journal of the Linnean Society. Linnean Society of London》2011,167(2):137-152
Paepalanthus subgenus Xeractis (Eriocaulaceae) comprises 28 recognized species endemic to the Espinhaço Range, in Minas Gerais state, Brazil. Most species of the subgenus are restricted to small localities and critically endangered, but still in need of systematic study. The monophyly of the subgenus has already been tested, but only with a few species. Our study presents the first phylogenetic hypothesis within the group, based on morphology. A maximum parsimony analysis was conducted on a matrix of 30 characters for 30 terminal taxa, including all species of the subgenus and two outgroups. The biogeographical hypotheses for the subgenus were inferred based on dispersal–vicariance analysis (DIVA). The analysis provided one most‐parsimonious hypothesis that supports most of the latest published subdivisions (sections and series). However, some conflicts remain concerning the position of a few species and the relationships between sections. The distribution and origin(s) of microendemism are also discussed, providing the ground for conservation strategies to be developed in the region. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 167 , 137–152. 相似文献
6.
INDUCTION OF OOCYTE MATURATION BY DISULFIDE-REDUCING AGENT IN THE SEA CUCUMBER, STICHOPUS JAPONICUS 总被引:1,自引:1,他引:0
1-Methyladenine (1-MeAde) is known to be a natural inducer of starfish oocyte maturation. Disulfide-reducing agents such as dithiothreitol (DTT) and 2, 3-dimercapto-1-propanol (BAL) are known to mimic the action of 1-MeAde in inducing starfish oocyte maturation. Although 1-MeAde failed to induce oocyte maturation in sea cucumbers, breakdown of germinal vesicles and subsequent meiotic behaviour of chromosomes were induced by the treatment with DTT in the pronase-treated oocytes of the sea cucumber, Stichopus japonicus. These findings suggest that reduction of disulfide bonds plays an important role in triggering oocyte maturation in some marine forms such as echinoderms. 相似文献
7.
PHILIPPE BULET TAKEO KISHIMOTO HIROKO SHIRAI 《Development, growth & differentiation》1985,27(3):243-250
1-Methyladenine (1-MeAde) is the endogenous maturation-inducing substance (MIS) in starfish. However, small oocytes have no competence to 1-MeAde even at the concentration of 10?5M. Furthermore, when they were injected with cytoplasm of fully-grown (large) and maturing (1-MeAde-treated) oocytes, known to contain maturation-promoting factor (MPF), they did not undergo germinal vesicle breakdown (GVBD). On the other hand, germinal vesicles (GV) of the small oocytes underwent nuclear breakdown when the small oocytes were fused with the large maturing oocytes. Therefore it is concluded that the GV of the small oocytes are capable of undergoing nuclear breakdown in the presence of the sufficient MPF, but that the small oocytes can not amplify the injected MPF. Fused cells displayed particular shape changes during the course of nuclear breakdown of both the large and the small oocytes. 相似文献
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9.
YO TOMA FABIÁN G. FERNÁNDEZ SYOHEI SATO MIKI IZUMI RYUSUKE HATANO TOSHIHIKO YAMADA AYA NISHIWAKI GERMÁN BOLLERO J. RYAN STEWART 《Global Change Biology Bioenergy》2011,3(2):116-134
Species in the Miscanthus genus have been proposed as biofuel crops that have potential to mitigate elevated atmospheric carbon dioxide (CO2) levels and nitrous oxide (N2O) and methane (CH4) emissions. Miscanthus sinensis is widespread throughout Japan and has been used for biomass production for centuries. We assessed the carbon (C) budget and N2O and CH4 emissions over the growing season for 2 years in a M. sinensis‐dominated grassland that was naturally established around 1972 in Tomakomai, Hokkaido, Japan, which is near the northern limit for M. sinensis grassland establishment on Andisols. Average C budget was ?0.31 Mg C ha?1, which indicates C was released from the grassland ecosystem to the atmosphere. Dominant components in the C budget appeared to be aboveground net primary production of plants (1.94–2.80 Mg C ha?1) and heterotrophic respiration (2.27–3.11 Mg C ha?1). The measurement of belowground net primary production (BNPP) of plants in the M. sinensis grassland was extremely variable, thus only an approximate value could be calculated. Mean C budget calculated with the approximated BNPP value was 1.47 and ?0.23 Mg C ha?1 for 2008 and 2009, respectively. Given belowground biomass (9.46–9.86 Mg C ha?1) was 3.1–6.5 times higher than that of aboveground biomass may provide additional evidence suggesting this grassland represents a C sink. Average CH4 emissions across years of ?1.34 kg C ha?1 would indicate this grassland acts as an atmospheric CH4 sink. Furthermore, average N2O emissions across years were 0.22 kg N ha?1. While the site may contribute N2O to the atmosphere, this value is lower compared with other grassland types. Global warming potential calculated with the approximated BNPP value was ?5.40 and 0.95 Mg CO2 Eq ha?1 for 2008 and 2009, respectively, and indicates this grassland could contribute to mitigation of global warming. 相似文献
10.
Regulation of Metaphase by a Maturation-Promoting Factor 总被引:4,自引:4,他引:0
TAKEO KISHIMOTO 《Development, growth & differentiation》1988,30(2):105-115