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1.
The orientation of the superior articular processes with regard to the upper end-plate of the sacrum does not depend on the inclination of the sacrum. This assertion can be made by interpreting certain angles already described in literature and may be confirmed by a research following strict biomechanic principles: The orientation of the articular processes is put in relation to the direction of the forward shear brought upon by the Vth lumbar vertebra and caused by the inclination of the sacrum. This is achieved by measuring the angle between the articular facet and a plane normal to the mentioned forward shear. The result is that the size of this angle does not at all depend on the degree of the inclination of the sacrum. 相似文献
2.
Polyphenol oxidase (PPO) appears to be ubiquitous in higher plants but, as yet, no function has been ascribed to it. Herein, we report on the localization of PPO based upon biochemical fractionation of chloroplast membranes in Vicia faba (broad bean) into various complexes and immunocytochemical electron microscopic investigations. Sucrose density gradient fractionations of thylakoid membranes after detergent solubilization reveals that PPO protein (by reactivity with anti-PPO antibody) and activity (based upon ability to oxidize di-dihydroxyphenylalanine) are found only in fractions enriched in photosystem II (PSII). Furthermore, of the PSII particles isolated using three different protocols utilizing several plant species, all had PPO. Immunogold localization of PPO on thin sections reveals exclusive thylakoid labeling with a distribution pattern consistent with other PSII proteins (80% grana, 20% stroma). These data strongly indicate that PPO is at least peripherally associated with the PSII complex. 相似文献
3.
Evidence that the 5'-untranslated leader of mRNA affects the requirement for wheat germ initiation factors 4A, 4F, and 4G 总被引:6,自引:0,他引:6
K S Browning S R Lax J Humphreys J M Ravel S A Jobling L Gehrke 《The Journal of biological chemistry》1988,263(20):9630-9634
The efficiency of translation of alfalfa mosaic virus (AMV) RNA 4, barley alpha-amylase (B alpha A) mRNA, and two chimeric mRNAs, AMV 4-B alpha A and B alpha A-AMV 4 (in which the 5' leader sequences of the two mRNAs were interchanged), was measured in an S30 extract from wheat germ and a fractionated system from wheat germ in which translation could be made dependent upon initiation factor (eIF) 3, 4A, 4F, or 4G. In the S30 system, AMV RNA 4 and the chimeric mRNA AMV 4-B alpha A are translated much more efficiently than B alpha A mRNA and the chimeric mRNA B alpha A-AMV 4. When the S30 system was supplemented with high amounts of purified eIF-3, eIF-4A, eIF-4F, and eIF-4G, B alpha A and B alpha A-AMV 4 mRNAs were translated as efficiently as AMV RNA 4 and AMV 4-B alpha A mRNA. These findings indicated that the mRNAs containing the B alpha A leader sequence required higher amounts of one or more of the initiation factors (eIF-3, eIF-4A, eIF-4F, and eIF-4G) for efficient translation. Determination of the amounts of the initiation factors required for translation in the fractionated system showed that AMV RNA 4 required 2-4-fold lower amounts of eIF-3, eIF-4A, eIF-4F, and eIF-4G than did B alpha A mRNA. Replacement of the B alpha A leader sequence with that of AMV RNA 4 decreased the amounts of eIF-4A, eIF-4G, and eIF-3 required, but did not affect the amount of eIF-4F required. Replacement of the AMV RNA 4 leader sequence with that of B alpha A mRNA increased the amounts of eIF-4F, eIF-4G, and eIF-3 required, but did not affect the amount of eIF-4A required. These data strongly suggest that the amounts of the factors required are affected not only by the 5' leader itself but also by interactions between the 5' leader and a region(s) of the mRNA 3' to the initiation codon. 相似文献
4.
Antibodies against a synthetic peptide as a probe for the kinase activity of the avian EGF receptor and v-erbB protein 总被引:77,自引:0,他引:77
The transforming protein v-erbB of avian erythroblastosis virus (AEV) displays extensive sequence homology with the presumptive protein-tyrosine kinase domain of the human EGF receptor and with the src protein-tyrosine kinase family of oncogenes. However, no kinase activity has previously been demonstrated for the v-erbB protein. Here antibodies generated against a synthetic peptide from the C terminus of human EGF receptor are shown to immunoprecipitate the EGF receptor from human and avian cells, as well as the v-erbB proteins from AEV-transformed cells that become phosphorylated on tyrosine residues upon the addition of gamma-32P-ATP. The immunoprecipitates are also able to phosphorylate exogenous tyrosine-containing substrates. Hence, it is likely that both avian EGF receptor and v-erbB proteins are protein tyrosine-specific protein kinases. Since the kinase activity of v-erbB protein cannot be regulated by EGF, it is proposed that the tyrosine protein kinase function of v-erbB may be constitutively activated. 相似文献
5.
We developed a mathematical model and an algorithm for numerical treatment of a model of honeycomb construction in a beehive. The model contains essential features of the bee-bee and bee-wax interactions, and in a qualitative way captures the dynamics of parallel comb construction. The construction is represented by a set of dynamical coupled partial differential equations for the density of bees situated on the hive ceiling, and the quantity of wax distributed by the bees. A spectral algorithm is invented for treatment of these equations, based on a modified thin-sheet gain scheme and a fast Fourier transform technique.Work at City College supported in part by the Army Research Office and the Department of Energy 相似文献
6.
The virulence plasmid of Salmonella dublin: detailed restriction map and analysis by transposon mutagenesis 总被引:10,自引:0,他引:10
A J Lax G D Pullinger G D Baird C M Williamson 《Journal of general microbiology》1990,136(6):1117-1123
A detailed restriction map of the virulence plasmid of Salmonella dublin has been determined and used for comparison with the virulence plasmid from S. typhimurium. Two regions were identified which appeared to be similar based on blotting and restriction data. One, of about 22 kb, encompassed the virulence region; the other, of about 8 kb, was outside it. The locations of 259 transposon insertions on the S. dublin plasmid were determined and related to their effect on virulence. One gene involved in virulence but outside the essential virulence region was shown to affect citrate metabolism. 相似文献
7.
Iturin A: A potential new fungicide for stored grains 总被引:6,自引:0,他引:6
The removal of many synthetic fungicides from the market has created a demand for new, environmentally safe fungicides. Iturin A, a cyclic lipopeptide produced byBacillus subtilis, has strong antifungal properties and low mammalian toxicity. To determine the efficacy of this compound as a potential fungicide on stored feed grains, lots of corn, peanuts and cottonseed were treated with varying concentrations of iturin A. The mycoflora of treated seed was assayed along with that of untreated seed and seed treated with fungicides used commercially for planting seed. Fungal species varied considerably in their sensitivity to iturin A. Significant reductions in total mycoflora occurred in most seed lots tested at iturin A concentrations of 50 to 100 ppm. 相似文献
8.
Regulation of spvR, the positive regulatory gene of Salmonella plasmid virulence genes 总被引:4,自引:0,他引:4
Jayne M. Spink Gillian D. Pullinger Michael W. Wood Alistair J. Lax 《FEMS microbiology letters》1994,116(1):113-121
Abstract The regulation of the spvR promoter from the Salmonella dublin virulence plasmid was monitored using proter-reporter gene fusion constructs. Activity was dependent upon the presence of the spv region and was affected by the number of copies of the spv region present with the cell. Activity remained constant throughout exponential growth, and increased rapidly with the onset of stationary phase, under both aerobic and anaerobic conditions. Additionally, the level of spvR expression was controlled by the availability of iron, activity being greatest under low iron conditions in stationary phase. The spvA gene product negatively regulated spvR expression in a dose-dependent manner, indicating that SpvA provides a negative feedback mechanism for this operon. 相似文献
9.
10.
Daniela Cocchi Angela Santagostino Irit Gil-Ad Sergio Ferri Eugenio E. Müller 《Life sciences》1977,20(12):2041-2046
The effect of Leu5-enkephalin on growth hormone (GH) and prolactin (PRL) release was studied in the infant rat and compared to that of morphine. In 10 day-old pups, intracerebroventricular injection of Leu5-enkephalin (50, 75 and 100 μg) resulted in a dose-related increase in plasma GH; morphine was active as GH releaser at the dose of 5 and 10 μg, but not at 2.5 μg. Pretreatment with naloxone (2 mg/kg ip) suppressed the GH-releasing effect of either Leu5-enkephalin (100 μg) or morphine (10 μg). Leu5-enkephalin (75 and 100 μg) induced a rise in plasma PRL which was neither dose-related nor antagonized by naloxone; morphine (5 and 10 μg) was active as PRL releaser and its effect was antagonized by naloxone. These results indicate that: 1) Leu5-enkephalin stimulates both GH and PRL release; 2) the release of GH by Leu5-enkephalin but likely not that of PRL involves specific opiate receptors; 3) morphine releases GH and PRL through specific opiate receptors. 相似文献