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71.
72.
Sorbitol dehydrogenase genetics in the mouse: A ';null' mutant in a ';European' C57BL strain 总被引:1,自引:0,他引:1
A ';null' activity variant phenotype for sorbitol dehydrogenase (SDH) was observed in C57BL/LiA mice and used to examine the genetics of this enzyme. Linkage studies of the locus ( Sdh-1 ) with non-agouti (a) and a biochemical Iocus encoding liver L-α-hydroxyacid oxidase ( Hao-1 ) demonstrated that it is coincident with or closely linked to the structural locus, previously localized on chromosome 2. Alcohol dehydrogenase (ADH) isozymes were also examined, since the liver A2 isozyme exhibited some activity as a sorbitol dehydrogenase on cellulose acetate zymograms. It is apparent that SDH activity is not ';essential' in this mouse strain. 相似文献
73.
74.
Roger D. Meicenheimer 《American journal of botany》1981,68(8):1139-1154
Preliminary studies establishing relationships between leaf plastochron index and Epilobium hirsutum L. shoot growth provide a method for rigorous selection of plants utilized in experiments designed to test the working hypothesis that endogenous auxin gradient interactions are factors of phyllotactic control in this species. Application of N-1-naphthylphthalamic acid (NPA), an auxin transport inhibitor, to one of the youngest bijugate primordia on the shoot meristem results in increased growth of the treated primordium. Fasciation between the treated primordium and one of the next primordia to be initiated alters relative vertical spacing of primordia. Angular shifts between subsequent primordia result in spiral transformation of Epilobium bijugate phyllotaxy. Application of α-4-chlorophenoxyisobutyric acid (CPIB), an auxin antagonist, to one of the youngest bijugate primordia on the shoot meristem results in decreased growth of the treated primordium that alters both radial and vertical spacing of primordia. This is followed by angular shifts between subsequent primordia resulting in spiral transformation of the bijugate phyllotaxy. Changes in the growth parameters of NPA- and CPIB-treated shoots are similar. Relative plastochron rates of radial and vertical shoot growth of induced spiral shoots are about half those of lanolin paste control shoots, as are the plastochrons and relative plastochron rates of leaf elongation. Treated shoot meristems have eccentricities of 0.5 as compared to bijugate control meristem eccentricities of 0.7. No significant difference is apparent between basal transverse areas of treated and control shoot meristems. The relative chronological rates of growth of treated shoots are not significantly different from those rates of control shoots. Spiral transformation results from changes in relative positions of leaf primordia insertion on the shoot meristem, not from changes in growth of treated shoots. These changes are accompanied by an increased rate of leaf initiation on a more circular shoot meristem. Existing theoretical models of phyllotaxy are discussed in relation to these chemically induced changes of Epilobium leaf arrangement. 相似文献
75.
Thermal Denaturation of Native Striatal Tyrosine Hydroxylase: Increased Thermolability of the Phosphorylated Form of the Enzyme 总被引:5,自引:5,他引:0
Mitchell A. Lazar Roger J. W. Truscott Joachim D. Raese Jack D. Barchas 《Journal of neurochemistry》1981,36(2):677-682
Tyrosine hydroxylase was purified from bovine corpus striatum. The native enzyme had a half-life of 15 +/- 3 min at 50 degrees C. Phosphorylation of tyrosine hydroxylase with protein kinase purified from both corpus striatum and heart activated the enzyme, but activity was rapidly lost with additional preincubation of the enzyme at 30 degrees C. Thermal denaturation studies indicated that phosphorylated tyrosine hydroxylase had a half-life of 5 +/- 2 min at 50 degrees C 相似文献
76.
Roger Schallreuter 《Pal?ontologische Zeitschrift》1980,54(3-4):313-318
A problematical, axial-symmetrical microfossil is described from Upper Ordovician Öjlemyrflint erratic boulders of the Isle of Gotland (Baltic Sea) and of the Kaolinsand (Plio-/Pleistocene) of the Isle of Sylt (North Sea). 相似文献
77.
Summary Pokeweed mitogen (PWM) and ricin are both lectins derived from plant seeds. They are glycoproteins and share the ability to
agglutinate a variety of animal cells including erythrocytes. The effect of these two lectins on protein synthesis was studied
in four longterm lymphoblastoid lines (8866 and GM1531, which are B cell lines; and CCRF/CEM and MOLT 4, which are T-cell
lines). Ricin (50 μg/ml) completely inhibited protein synthesis by 2 hr in both B-cell and T-cell lines as measured by the
uptake to [3H]leucine. The PWM appeared more specific and at a concentration of 500 μg/ml inhibited protein synthesis only in B-cell lines
(8866 and GM 1531). This effect was maximal at 5 hr. To investigate the reason for the differential effect of PWM on T and
B cells,125I-labeled PWM was incubated with 8866, MOLT 4, and CCRF/CEM to see if a significant difference in binding to B cells and T
cells could be demonstrated.
It does not appear that the differential effect on T and B cells is due to a difference in the amount of PWM bound. On the
other hand it is possible that the B cells may bind some toxic subcomponent of the PWM preparation that the T cells do not
bind because of a difference in composition or arrangement of cell surface glycoproteins. 相似文献
78.
79.
The intracellular location of adenylyl cyclase in the cellular slime molds Dictyostelium discoideum and Polysphondylium pallidum 总被引:1,自引:0,他引:1
Adenylyl cyclase activity was low or not detectable on intact cells and in isolated plasma membranes, phagocytic vacuoles and nuclei of the two slime mold species examined. The entire activity of homogenates was sedimentable and concentrated in a light membrane fraction. When this fraction was centrifugated through sucrose density gradients the adenylyl cyclase activity sedimented differently from all other enzymes measured. The gradient fractions with the highest specific activity of adenylyl cyclase consisted mainly of small vesicles. No changes in adenylyl cyclase distribution were associated with development. The possibility that cellular slime mold adenylyl cyclase activity is associated with vesicles in vivo, as already suggested by Maeda & Gerisch [10], is discussed. 相似文献
80.