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排序方式: 共有173条查询结果,搜索用时 15 毫秒
1.
YONG-JIANG ZHANG FREDERICK C. MEINZER GUANG-YOU HAO FABIAN G. SCHOLZ SANDRA J. BUCCI FREDERICO S. C. TAKAHASHI RANDOL VILLALOBOS-VEGA JUAN P. GIRALDO KUN-FANG CAO WILLIAM A. HOFFMANN & GUILLERMO GOLDSTEIN 《Plant, cell & environment》2009,32(10):1456-1466
Size-related changes in hydraulic architecture, carbon allocation and gas exchange of Sclerolobium paniculatum (Leguminosae), a dominant tree species in Neotropical savannas of central Brazil (Cerrado), were investigated to assess their potential role in the dieback of tall individuals. Trees greater than ∼6-m-tall exhibited more branch damage, larger numbers of dead individuals, higher wood density, greater leaf mass per area, lower leaf area to sapwood area ratio (LA/SA), lower stomatal conductance and lower net CO2 assimilation than small trees. Stem-specific hydraulic conductivity decreased, while leaf-specific hydraulic conductivity remained nearly constant, with increasing tree size because of lower LA/SA in larger trees. Leaves were substantially more vulnerable to embolism than stems. Large trees had lower maximum leaf hydraulic conductance ( K leaf ) than small trees and all tree sizes exhibited lower K leaf at midday than at dawn. These size-related adjustments in hydraulic architecture and carbon allocation apparently incurred a large physiological cost: large trees received a lower return in carbon gain from their investment in stem and leaf biomass compared with small trees. Additionally, large trees may experience more severe water deficits in dry years due to lower capacity for buffering the effects of hydraulic path-length and soil water deficits. 相似文献
2.
HIROYA TAKAHASHI 《Development, growth & differentiation》1975,17(2):167-175
In the guppy, Poecilia reticulata , ovarian differentiation occurs during the embryonal life by 14 days after the preceding parturition. Testicular differentiation begins with the appearance of prominent aggregations of stroma cells in the gonadal hilus occurring by 18 days following the last parturition.
Oral administration of methyltestosterone (400 μ/g diet) to gravid guppies, begun 13–15 days after the preceding parturition and continued until the end of gestation, induced a male-type aggregation of somatic cells in the hilus of ovaries of female embryos. Gonads of newly born, androgenized females still had developing oocytes but were always provided with atypical clusters of stroma cells in their hilus. The gonads of affected female offspring developed successively into definite testes within 20 days after birth, displaying a precocious differentiation of the hilar stroma into sperm ducts and testicular interstitium, a concomitant initiation of spermatogenesis, and a conspicuous degeneration of oocytes. A successful masculinization of the somatic element, which may occur prior to that of the germ cells, in androgen-affected embryonic ovaries seems to be essential for the functional sex reversal of genetic females in the guppy. 相似文献
Oral administration of methyltestosterone (400 μ/g diet) to gravid guppies, begun 13–15 days after the preceding parturition and continued until the end of gestation, induced a male-type aggregation of somatic cells in the hilus of ovaries of female embryos. Gonads of newly born, androgenized females still had developing oocytes but were always provided with atypical clusters of stroma cells in their hilus. The gonads of affected female offspring developed successively into definite testes within 20 days after birth, displaying a precocious differentiation of the hilar stroma into sperm ducts and testicular interstitium, a concomitant initiation of spermatogenesis, and a conspicuous degeneration of oocytes. A successful masculinization of the somatic element, which may occur prior to that of the germ cells, in androgen-affected embryonic ovaries seems to be essential for the functional sex reversal of genetic females in the guppy. 相似文献
3.
Some workers have reported that the breaking of seed dormancyin rice (O. sativa L.) is usually enhanced by higher oxygentension, whereas others have shown that rice seed dormancy canbe broken by incubation under anaerobic conditions. This articleaims to clarify this paradox. The results show that high oxygentensions inhibit seed germination for a certain period afterharvest in Japonica rice, whereas Indica rice cultivars arenot inhibited by oxygen at any stage. Oxygen inhibition, seed germination, aquatic plants, Japonica rice, Indica rice 相似文献
4.
Histological Detection of Chicken δ-Crystallin DNA Sequences Introduced into Mouse Teratocarcinoma Cell Lines 总被引:1,自引:1,他引:0
YOSHIKO TAKAHASHI T. S. OKADA HISATO KONDOH 《Development, growth & differentiation》1985,27(5):607-613
In situ hybridization techniques to detect specific DNA sequences in histological sections were developed for the purpose of analyzing experimental chimeras produced by combination of mouse teratocarcinoma (TCC) cells stably carrying chicken δ-crystallin DNA sequences and normal mouse embryos. Various hybridization conditions for detection of exogenous DNA sequences were compared in samples of solid tumors of TCC lines. Of the conditions examined, denaturation of DNA in alkali and hybridization at 68°C in 6x SSC in the presence of dextran sulphate was the best for detecting δ-crystallin DNA sequences. With 3 H-labelled probe under these conditions, virtually all nuclei containing more than 100 copies of chicken δ-crystallin sequences were labelled sufficiently to be distinguishable from nuclei without chicken sequences. This technique could be applied to other experimental chimeras in which specific DNA sequences can be used as markers of certain cell lineages. 相似文献
5.
MASAHIRO SATO SHUN-ICHIROH OGATA RYUZO UEDA REIKO NAMIKAWA TOSHITADA TAKAHASHI TAKAO NAKAMURA EIICHI SATO TAKASHI MURAMATSU 《Development, growth & differentiation》1983,25(4):333-344
C-9-1, a monoclonal IgM antibody raised against human null cell acute lymphocytic leukemia cells reacted with restricted regions of embryonic and adult tissues of the mouse. The antigen positive sites in the embryos included embryonic ectoderm, visceral endoderm, trophoblastic cells invading the maternal decidua of 5∼7-day embryos, primordial germ cells of 10∼12-day embryos, epithelium of nasal chamber, the bronchus, Mullerian duct, epididymis and bladder of 12∼17-day embryos. In the adult mice, C-9-1 antigen was detected in renal tubules, a part of stomach, bladder, endometrium and epididymal sperm. Embryonal carcinoma cells, but not endodermal cells of teratocarcinoma expressed the antigen. Thus, C-9-1 antigen showed distribution similar to SSEA-1. However, C-9-1 antigen was not detected in preimplantation embryos, nor in oviduct, both of which are positive for SSEA-1. 相似文献
6.
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
7.
Auxin-induced heritable variants in yeast with special reference to physiological and genetic characters 总被引:1,自引:0,他引:1
YANAGISHIMA NAOHIKO; SHIMODA CHIKASHI; KAMISAKA SEIICHIRO; TAKAHASHI TOSHIAKI 《Plant & cell physiology》1968,9(2):323-331
A high concentration (400 mg/l) of an auxin, -naphthaleneaceticacid produced heritable variants differing in cell form andsize and in sporulation ability in a diploid strain of Saccharomycescerevisiae. These variants showed altered absorption spectrain the region of cytochromes a + a3, b and/or c, but could growin a glycerol medium. Cultures of dissected spores from thesevariants involved many non-maters. These variants showed irregularsegregation of nutritional markers and/or a high DNA contentper cell. Since most of the variants grow more slowly on anauxin medium than does the original strain, they seem to beproduced by the induction by auxin rather than by selectiveenrichment. Genetic control of the ability to respond to auxinand the biological significance of auxin-induced variation inyeast is discussed. (Received January 12, 1968; ) 相似文献
8.
Daily alternating temperatures or a short exposure to low orhigh temperatures were necessary for the germination of eggplantseeds at the initial stage of after-ripening. But requirementsbecame less strict with the progress of after-ripening, andafter 4 to 8 months of afterripening, germination occurred easilyboth at constant (20 and 25) and daily alternating temperatures(30 for 16hrs and then 20 for 8hrs). With further progress in after-ripening, however, daily alternatingtemperatures or a short exposure to low or high temperaturesbecame again indispensable for attaining a high percentage ofgermination. The progress of after-ripening was greatly influencedby the degree of seed ripening, that is, by the period beforethe seeds were sampled from fruits after anthesis (ripening). The effect of GA on the germination of egg plant seeds varieddepending on the concentration of GA, temperature and the degreeof maturity (ripening and after-ripening) of the seeds. (Received March 8, 1968; ) 相似文献
9.
Exogastrulation is induced by chilling in several species of sea urchins, including Strongylocentrotus intermedius, Strongylocentrotus nudus, Pseudocentrotus depressus and Anthocidaris crassispina , but not in Hemicentrotus pulcherrimus. When early gastrulae are raised at low temperatures, no pseudopodia of secondary mesenchyme cells are formed, but the invagination of the endodermal plate occurs normally. When gastrulae in later stage having pseudopodia are chilled, the pseudopodia withdraw and the archenteron begins to retract, resulting in exogastrulation. The exogastrulae are also induced when the larvae are raised in the presence of colchicine, vinblastine, cytochalasin B or cytochalasin C. The formation of exogastrula induced by chilling is presumed to be caused by the depolymerization of microtubules in the secondary mesenchyme cells and their pseudopodia. The fully invaginated archenteron of the late gastrula, even when it is chilled, remains within the blastocoel and does not evaginate.
The effectiveness of low temperature treatment in inducing exogastrulation may be related to the environmental temperature at the breeding season of the animal. 相似文献
The effectiveness of low temperature treatment in inducing exogastrulation may be related to the environmental temperature at the breeding season of the animal. 相似文献
10.
TAKASHI KAGEYAMA SUSUMU Y. TAKAHASHI TADAKAZU OHOKA EIJI OHNISHI 《Development, growth & differentiation》1980,22(6):859-865
The mechanism of polyol accumulation in diapausing Bombyx eggs, conversion of [6-14 C] glucose-6-phosphate into polyols and other neutral sugars was investigated in in vitro reaction systems. When a crude homogenate or a press juice of the eggs was incubated with [6-14 C]glucose-6-P, the labelled trehalose, sorbitol and glycerol accumulated in the reaction mixture. In the press juice incubation system of developing eggs at day 1, 14 C-sorbitol was detected in appreciable amounts, but it decreased rapidly with the development of the embryos. When the press juice was prepared from eggs in diapause, the formation of 14 C-sorbitol was 3–5 times greater in eggs at early stages (day 2 to day 4) than in developing eggs. 相似文献