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1.
MASAHISA NAKAMURA KEIICHIRO YAMAGUCHI AKIRA SUZUKI SHOICHI OKINAGA KIYOSHI ARAI 《Development, growth & differentiation》1986,28(5):499-504
Round spermatids (steps 1–8) were isolated from rat testes and glucose transport into the cells was examined. The exposure of spermatids to glucose resulted in an extremely low level of ATP. In contrast, the level of ATP remained constant in the presence of pyruvate. Transport of a glucose analogue, 2-deoxy-D-[3 H]glucose ([3 H]dGlc) into spermatids was correlated with intracellular levels of ATP and was much greater in cells with higher rather than lower levels of ATP. [3 H]dGlc transport into spermatids with low levels of ATP was partially reversed when the cells were incubated with pyruvate. Inhibition of [3 H]dGlc transport was exerted on Vmax and not on Km. Moreover, glucose acted as a competitive inhibitor of [3 H]dGlc uptake (Km increased; Vmax unaltered). These results suggest that glucose transport into spermatids is active in vitro and probably regulated by the intracellular level of ATP. 相似文献
2.
ITO OSAMU; OKANO KUNIO; KUROIWA MIYOKO; TOTSUKA TSUMUGU 《Journal of experimental botany》1985,36(4):652-662
Ten-day old kidney bean plants (Phaseolus vulgaris L. cv. Shin-edogawa)were exposed to 2.0 and 40 parts 106 NO2, and0.1, 0.2, and 0.4 parts 106 O3 alone or in combinationfor 2, 4, and 7 d. The effects of these air pollutants wereexamined with respect to the growth, partitioning of assimilates,nitrogen uptake, soluble sugar content, and root respiration. Decreased dry matter production was significant with all treatmentsexcept 2.0 parts 106 NO2 and 0.1 parts 106 O3.Exposure to mixtures of the gases produced more severe suppressionof growth than exposure to the single gases. Root/shoot ratiowas significantly lowered at 7 d by the gas treatments otherthan 2.0 parts 106 NO2 and 0.1 parts 106 O3. Thetotal nitrogen content of plants was increased by all treatments;the higher percent of nitrogen found with O3 exposure will resultfrom the growth retardation which increases the concentrationof nitrogen in the plants because the absorption of nitrogenby roots was unaffected. The combination of O3 with NO2 significantlydecreased the assimilation of NO2 by the plants. The concentration of soluble sugars in roots was decreased bythe gas treatments. There was a strong positive correlationbetween soluble sugar content and dry weight of the roots harvestedat 7 d. Root respiration was relatively unchanged until 5 dand then decreased significantly at 7 d by 2.0 parts 106NO2 and 02 parts 106 O3. Retarded growth of theroots and the decreased root respiration may be due to diminishedtranslocation of sugars from leaves to roots caused by exposureto air pollutants. The uptake of soil nitrogen was not closelyrelated with root respiration in the case of O3 exposure. Key words: NO2, O3, Phaseolus vulgaris, Growth, Sugars, Root respiration 相似文献
3.
Sericin gene expression in the middle silk glands during Bombyx mori larval development was analyzed using probes from a genomic DNA clone for 10.5 kb sericin mRNA. The 10.5 kb mRNA, the most abundant in the fifth instar, is not detected in the third feeding, fourth feeding and fourth moulting stages. It becomes detectable at 2 days of the fifth instar, and accumulates rapidly. The second major mRNA in the late fifth instar, a 9.0 kb component having a similar sequence to the 10.5 kb mRNA, becomes detectable only at 6 and 7 days of the instar by use of the repetitious coding sequence probe of the sericin clone. Using the same probe about 20 kb RNAs with a fainter intensity than that of the major mRNAs are detected. They are present extremely faintly in the third and fourth feeding stages, disappear in the fourth moulting stage, and increase in the fifth instar. Two other faint poly(A)+ RNA components are detected by a DNA probe containing the 5' end sequence of the sericin clone. One is 4.3 kb, and appears in the third, fourth and fifth feeding stages but not in the fourth moulting stage. The other is 3.0 kb, and it becomes detectable after 1 day of the fifth instar. 相似文献
4.
AKIRA NAGATANI HIDEHO SUZUKI MASAKI FURUYA 《Development, growth & differentiation》1983,25(2):217-226
Protein synthesis during photoinduced, synchronous progression of the cell cycle in single-celled protonemata of the fern Adiantum capillus-veneris was studied by tracer techniques. Nuclei of the protonemata were labelled with 3 H-thymidine during spore germination so that the amount of 3 H incorporated into the TCA-insoluble fraction of the cells could be used as a measure of the cell number in each sample. The rate of the incorporation of 14 C-amino acids into TCA-insoluble materials was not significantly varied at different stages of the cell cycle or by treatment with blue light. Extracts of cells labelled with 35 S-methionine at various times after the transfer from red light condition (G0 ) to darkness (G1 to S) were analyzed by two-dimensional gel electrophoresis. At least 3 of about 200 spots showed significant changes in intensity on fluorograms. Spot A (molecular weight 20,000, isoelectric point 6.3) was detectable only in early G1 , whereas spot B (molecular weight 19,500, isoelectric point 6.3) was found only in the late G1 and S phases. When the cells were exposed to blue light before the dark incubation, the times of disappearance of spot A and appearance of spot B were advanced depending upon the progression of the cell cycle but not upon the clock time. 相似文献
5.
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
6.
EFFECTIVE EXCITATION, PRECEDING THE MECHANICAL RESPONSE IN FROG TWITCH MUSCLES, INVOLVES TWO DISTINCT EVENTS: depolarization of the excitable membrane and the flow of internal currents. To distinguish between the effects of these two potential factors in activation of the contractile machinery, experiments ought to be conducted in which one or the other is excluded. Our experiments are designed to distinguish between these effects by indirect methods. Depolarization in a longitudinal electric field can be expected to be greatest at the ends where current leaves the muscle fibers (space constant at [K] = 16 mM/liter is >1 mm.), whereas the internal longitudinal current is known to be greatest in the middle portion. Depolarization, therefore, should affect the ends more strongly and internal current the middle portion. Our experiments show that non-propagating frog twitch muscles shorten, during isotonic work, along their whole length and not only at their ends, when effectively stimulated in a longitudinal A.C. field. At a field strength about twice the new threshold value (at [K](o) = 16 mM) shortening is distinctly greater in the middle portion of the muscle than at the ends. The muscles, although temporarily non-propagating, remain intact throughout the experiment, as demonstrated by complete recovery after repolarization. These findings may be taken as an indication that internal currents are more directly linked to activation than is depolarization, but the latter is an essential priming step, which must precede or coincide with effective current flow. 相似文献
7.
MASAHISA NAKAMURA AKIRA SUZUKI SHOICHI OKINAGA KIYOSHI ARAI 《Development, growth & differentiation》1984,26(5):497-502
The effects of adenosine monophosphate (AMP) and fructose 2, 6-bisphosphate (fruc-2, 6-P2 ) on the key-enzyme of gluconeogenesis, fructose 1, 6-bisphosphatase (fruc-P2 ase; D-fructose 1, 6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) in spermatid extract from rat testes were studied. The fruc-P2 ase activity in the spermatids of rats was suppressed by AMP and fruc-2, 6-P2 . The inhibition of fruc-2, 6-P2 was much stronger at low than at high substrate concentrations, and enhanced synergistically with AMP. The substrate saturation curve was changed by fruc-2, 6-P2 hyperbolic to sigmoidal. Furthermore, the concentration of AMP that decreased the activity to 50% was much lower in the presence than in the absence of fruc-2, 6-P2 . These results indicate the possibility that gluconeogenesis in spermatids of rats is controlled by AMP and fruc-2, 6-P2 . 相似文献
8.
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
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