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71.
External ATP enhanced stomatal opening of Commelina communis L. differently from EDTA. ATP was more effective in opening stomata than EDTA, when both were applied in amounts yielding equivalent free Ca2+ concentration. The stimulation by ATP depended upon its de-phosphorylation and was not due to the P1 released. Hence an energetical contribution of external ATP appears possible. Increase in CO2 concentration increased the stimulation of stomatal opening by ATP and diminished the internal ATP level, ATP/(ADP+AMP) ratio and respiration rate. 相似文献
72.
Summary Cell wall regeneration around protoplasts from Black Mexican Sweet corn suspension cells has been observed using scanning electron microscopy. A coherent array of cellulose microfibrils can be seen around protoplasts two hours after they have been isolated. This array does not form in the presence of 15 mg/l Congo Red. The frequency and electrical resistance of seals made between patch clamp pipettes and the plasmalemma around corn protoplasts is not significantly affected by the presence or absence of these fibrils (p0=0.75); it remains relatively low. Some single channel records from BMS corn protoplasts are shown. 相似文献
73.
A detailed investigation of hydrodynamic and conformational behavior has been made of the HM-crystallin and -crystallins of bovine lens. Results from this study indicated that HM (high-molecular-weight -crystallin) and (low-molecular-weight -crystallin) possess considerable size and charge heterogeneities in their native structures and subunit polypeptides, respectively. Sedimentation velocity showed a heterogeneous polydisperse system of HM with an average sedimentation coefficient of about 50 S and a more homogeneous system of -crystallin of 20 S. Viscosity and circular dichroism studies pointed to a compact and globular shape of dominant -sheet conformation for -crystallin, yet a highly asymmetrical and aggregated form for HM. The conformational stability of -crystallin was investigated in the presence of various denaturants. The evidence presented shows that hydrogen bonding is the main force in maintaining the quaternary structure of compact native -crystallin. Conformational flexibility of -crystallin demonstrated in the equilibrium unfolding study indicated a multistep transition that made the extraction of thermodynamic data from the heat denaturation study difficult. Temperature perturbation on -crystallin suggested the possible involvement of hydrophobic interaction in the aggregation process, leading to the formation of HM from -crystallin. The comparison of conformational properties between HM and -crystallin strongly indicated that HM is a denatured form of -crystallin. 相似文献
74.
Florence Levy-Favatier Lydie Tichnonicky Jacques Kruh Marc Delpech 《Biochimie》1989,71(11-12):1157-1161
We have previously described in rat liver two protein kinases tightly bound to DNA, one is serine-specific, the other arginine-specific. In this work we show that both enzymes are present in various rat tissues and in liver from various species. Both kinase specific activities are strongly decreased in methyl-DBA-induced hepatomas and in HTC cells but not in regenerating liver after hepatectomy. This decrease is then not related to cell proliferation. 相似文献
75.
Jackie R. Vandenheede Sigrid Staquet Wilfried Merlevede 《Molecular and cellular biochemistry》1989,87(1):31-39
Summary Fractionation of rabbit skeletal muscle cytosol on Aminohexyl-Sepharose has resulted in the identification of a latent ATP, Mg-dependent protein phosphatase whose catalytic subunit is in the active conformation, but is inhibited by the presence of more than one modulator unit. The partially purified enzyme is converted to an inactive, kinase FA-dependent form upon incubation at 30°C unless modulator-specific polyclonal antibodies are added to the preparation. The immunoglobulins also relieve the inhibition which is responsible for the low basal phosphatase activity of the enzyme, and they counteract all of the heat-stable inhibitor activity present in the preparation. Addition of free catalytic subunit abolishes the inhibition of the latent enzyme in a dose-dependent way, but cannot prevent the inactivation process. The inactivated phosphatase and the original latent enzyme exhibit the same apparent M
r in sucrose density-gradient centrifugation (70 000) and in gel filtration (110 000).Abbreviations PMSF
Phenylmethanesulphonyl Fluoride
- TLCK
L-l-chloro-3-(4-tosylamido)-7-amino2-heptanone-hydrochloride
- TPCK
L-l-chloro-3-(4-tosvlamido)-4-phenyl-2-butanone 相似文献
76.
Belinda Martineau H. Jane Smith Caroline Dean Pamela Dunsmuir John Bedbrook Laurens J. Mets 《Plant molecular biology》1989,13(4):419-426
We report the successful transformation, via Agrobacterium tumefaciens infection, and regeneration of two species of the genus Flaveria: F. brownii and F. palmeri. We document the expression of a C3 plant gene, an abundantly expressed ribulose 1,5-bisphosphate carboxylase/oxygenase small subunit gene isolated from petunia, in these C4 plants. The organ-specific expression of this petunia gene in Flaveria brownii is qualitatively identical to its endogenous pattern of expression. 相似文献
77.
Norway spruce somatic embryogenesis: high-frequency initiation from light-cultured mature embryos 总被引:8,自引:0,他引:8
Somatic embryos and rooted plantlets have been regenerated from light-initiated embryogenic callus derived from mature embryos of Picea abies. Under a 16 h photoperiod, mature zygotic embryos were cultured on a modified half-strength Murashige & Skoog medium without NH4NO3 and supplemented with 5 mM glutamine, 4.5 M N6-benzyladenine and 10.7 M naphthaleneacetic acid or 10 M 2,4-dichlorophenoxyacetic acid. White translucent embryogenic callus, proliferating from the callusing hypocotyl region after 3 weeks incubation, was isolated from the green non-embryogenic tissue and subcultured for over 12 months. Upon transfer of the embryogenic callus through a specific sequence of media, somatic embryos proceeded to mature, elongating and forming rings of cotyledonary leaves similar to those of zygotic embryos. Transferred to medium without growth regulators, the somatic embryos germinated and produced plantlets with green cotyledons, elongated hypocotyls and primary roots. 相似文献
78.
D. Q. Binh L. E. Heszky G. Gyulai E. Kiss A. Csillag 《Plant Cell, Tissue and Organ Culture》1989,18(2):195-200
Callus was induced from seeds of Puccinellia distans (L.) Parl. on MS medium supplemented with 2 mgl-1 2,4-dichlorophenoxyacetic acid and 0.5 mgl-1 kinetin. Morphogenesis initiation was achieved during subculture on medium containing 0.1 mgl-1 2,4-D. From the point of morphogenetic capacity, 3 types of callus were selected. High frequency of plant regeneration was obtained by selection of embryogenic type of callus, and culture on N6 medium and N6 medium supplemented with kinetin (5–10 mgl-1), or kinetin (2 mgl-1) and IAA (0.5 mgl-1). A high ratio of albinos among regenerants was observed. 相似文献
79.
Young leaf and internodal stem segments of Gaillardia pulchella, collected from wild species re-established in the greenhouse, were used to initiate callus on Murashige & Skoog medium supplemented
with NAA (2.0 mgl−1) and BA (0.4 mgl−1). Callus formed after 10 to 14 days in the dark. Cultures were transferred to fresh medium and placed under lighted conditions
where shoot formation occurred approximately 14 to 30 days after initiation. Callus sub-cultured at 14 to 21-day intervals
continued to produce primordia for several weeks. Flowers were produced by regenerated shoots maintained on MS medium, but
roots did not develop until the plantlets were transferred to soil conditions. 相似文献
80.
Calli of P. argentatum were grown on a newly designed liquid nutrient flow-through system which facilitated the subculturing of calli and delayed
browning for 6 weeks. Friable calli were obtained on half-strength Gamborg B5-medium supplemented with 0.05 mgl−1 2,4-dichlorophenoxyacetic acid. Shoots developed on media supplemented with 0.2 mgl−1 benzylaminopurine but lacking 2,4-dichlorophenocyacetic acid. 相似文献