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1.
2.
A cyclic-3',5'-GMP-dependent protein kinase was purified 7400-fold from the reproductive tract of female ascarids to a specific activity of 718 nmol min-1 mg-1 (histone as substrate). The yield of the preparation was 25%. The enzyme protein obtained was homogeneous as judged by isoelectrofocusing and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The native enzyme behaved as a dimer of two 82-kDa subunits in gel permeation chromatography on Superose 12. The protein kinase was inactive in the absence of cyclic purine nucleotides. Half-maximum velocity was obtained in the presence of 18 nM cGMP, whereas 400-fold higher concentrations of cAMP were required for the same activity. The enzyme underwent autophosphorylation in first-order kinetics (rate constant 0.054 min-1), leading to maximum incorporation of 0.96 phosphate per subunit. The autophosphorylation led to a 4-fold increase in Vmax, while the Km remained almost unchanged. In an extract from the reproductive tract, cGMP-stimulated phosphorylation was primarily observed in five proteins (molecular masses of 66, 60, 43, 30, and 25 kDa). These proteins also incorporated phosphate when isolated reproductive tracts were incubated in the presence of [32P]phosphate. The phosphate content in cellular proteins was enhanced when the incubation was performed in the presence of 10(-4) M of either octyl-cAMP or octyl-cGMP. In addition to the proteins mentioned above, however, six more electrophoretic bands containing radioactive phosphate were identified after in situ labeling of reproductive tracts with radioactive phosphate. 相似文献
3.
Effect of postnatal development on calcium currents and slow charge movement in mammalian skeletal muscle 总被引:16,自引:3,他引:13 下载免费PDF全文
Single- (whole-cell patch) and two-electrode voltage-clamp techniques were used to measure transient (Ifast) and sustained (Islow) calcium currents, linear capacitance, and slow, voltage-dependent charge movements in freshly dissociated fibers of the flexor digitorum brevis (FDB) muscle of rats of various postnatal ages. Peak Ifast was largest in FDB fibers of neonatal (1-5 d) rats, having a magnitude in 10 mM external Ca of 1.4 +/- 0.9 pA/pF (mean +/- SD; current normalized by linear fiber capacitance). Peak Ifast was smaller in FDB fibers of older animals, and by approximately 3 wk postnatal, it was so small as to be unmeasurable. By contrast, the magnitudes of Islow and charge movement increased substantially during postnatal development. Peak Islow was 3.6 +/- 2.5 pA/pF in FDB fibers of 1-5-d rats and increased to 16.4 +/- 6.5 pA/pF in 45-50-d-old rats; for these same two age groups, Qmax, the total mobile charge measurable as charge movement, was 6.0 +/- 1.7 and 23.8 +/- 4.0 nC/microF, respectively. As both Islow and charge movement are thought to arise in the transverse-tubular system, linear capacitance normalized by the area of fiber surface was determined as an indirect measure of the membrane area of the t-system relative to that of the fiber surface. This parameter increased from 1.5 +/- 0.2 microF/cm2 in 2-d fibers to 2.9 +/- 0.4 microF/cm2 in 44-d fibers. The increases in peak Islow, Qmax, and normalized linear capacitance all had similar time courses. Although the function of Islow is unknown, the substantial postnatal increase in its magnitude suggests that it plays an important role in the physiology of skeletal muscle. 相似文献
4.
In addition to known derivatives, four new sesquiterpene-coumarin ethers were isolated from the roots of Achillea ochroleuca and Artemisia tripartita and identified by 1H and 13C NMR spectroscopy, including lanthanide induced shifts. The new compounds are isofraxidin derived ethers which differ from the previously described derivatives by ring cleavage and methyl migration within the terpenoid unit. The chemosystematic importance of sesquiterpene-coumarin ether accumulation within the two genera is briefly discussed. 相似文献
5.
Flow DNA-cytometric findings of paraffin-embedded primary cutaneous melanomas related to prognosis 总被引:1,自引:0,他引:1
C Lindholm P A Hofer H Jonsson B Tribukait 《Virchows Archiv. B, Cell pathology including molecular pathology》1989,58(2):147-151
In a retrospective study flow cytometry was performed in 82 paraffin-embedded clinical stage I cutaneous melanomas. A significant correlation of ploidy to melanoma thickness was found. Using a log rank test ploidy was found significant for prognosis. However, using the Cox's proportional hazard test the influence of ploidy vanished and melanoma thickness or Clark level of invasion together with sex and location were the factors most important for prognosis. 相似文献
6.
7.
Lack of association of bovine MHC class I alleles with carcass and reproductive traits 总被引:1,自引:0,他引:1
The present study was carried out to examine whether a relationship between bovine major histocompatibility complex (BoLA) class I alleles and carcass traits or reproductive performance exists in Braunvieh and Fleckvieh A1 (artificial insemination) bulls. The influence of BoLA class I (BOLA-A) alleles on deregressed breeding values for net growth rate, carcass index and thigh volume was assessed in Braunvieh crosses and Fleckvieh bulls with a gene substitution model. The reproductive traits: non-return rate and interval between first and last insemination of daughters (female fertility), as well as non-return rate of inseminated cows (male fertility), were only investigated in Fleckvieh animals. No influence of the BOLA-A region on the traits evaluated could be demonstrated. An improper, i.e. less restrictive analysis would have led to spurious results. 相似文献
8.
G. Sekaninová M. Hofer I. Rychlík J. Pillich M. Kolářová V. Zajícová D. Kubíčková 《Folia microbiologica》1994,39(5):381-386
A new bacteriophage typing set, composed of 22 phages, was established as a tool for differentiation ofProteus strains. All the phages were tailed and included 4 morphological types (A1, A2, B1 and C1). They were classified into the
familiesMyoviridae, Siphoviridae andPodoviridae. From the set, 19 phages had double-stranded DNA and 3 were single-stranded DNA phages. 相似文献
9.
10.
Molecular evolution of voltage-sensitive ion channel genes: on the origins of electrical excitability 总被引:14,自引:0,他引:14
We have analyzed nucleic acid and amino acid sequence alignments of a
variety of voltage-sensitive ion channels, using several methods for
phylogenetic tree reconstruction. Ancient duplications within this family
gave rise to three distantly related groups, one consisting of the Na+ and
Ca++ channels, another the K+ channels, and a third including the cyclic
nucleotide-binding channels. A series of gene duplications produced at
least seven mammalian homologues of the Drosophila Shaker K+ channel;
clones of only three of these genes are available from all three mammalian
species examined (mouse, rat, and human), pointing to specific genes that
have yet to be recovered in one or another of these species. The
Shaw-related K+ channels and the Na+ channel family have also undergone
considerable expansion in mammals, relative to flies. These expansions
presumably reflect the needs of the high degree of physiological and
neuronal complexity of mammals. Analysis of the separate domains of the
four-domain channels (Ca++ and Na+) supports their having evolved by two
sequential gene duplications and implies the historical existence of a
functional two-domain channel.
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