DNA conformation is determined by economics in the hydration of phosphate groups

Mixed sequence DNA can exist in two right-handed and one left-handed double helical conformations--A, B and Z. Under conditions of high water activity the B conformation prevails. If the water activity is reduced on addition of salt or organic solvents, transformation occurs to A-DNA or, in DNAs with alternating purine-pyrimidine sequences, to the left-handed Z-DNA. In crystal structure analyses of oligonucleotides, the free oxygen atoms of adjacent phosphate groups along the polynucleotide chain in B-DNA are found at least 6.6 A apart and individually hydrated whereas they are as close as 5.3 A in A-DNA and 4.4 A in Z-DNA, and bridged by water molecules. We suggest that this more economical hydration in A- and Z-DNA compared with B-DNA is the underlying cause of B----A and B----Z transitions.     

An analysis of allozyme,mitochondrial DNA and morphological variation in mussel (Mytilus galloprovincialis) populations from Greece

Three populations ofM. galloprovincialis from northern Greece were investigated using isozyme analysis, discriminant analysis of morphological characteristics and analysis of restriction fragments of mtDNA. For all three types of analysis significant intra- and interpopulation differentiation was found. This differentiation is very noticeable at the mtDNA genotype frequencies. Furthermore, the restriction patterns of mtDNA were different from those reported for Atlantic populations of this species.     

Multiple dopamine D4 receptor variants in the human population.

The dopamine D4 receptor structurally and pharmacologically resembles the dopamine D2 and D3 receptors. Clozapine, an atypical antipsychotic that is relatively free of the adverse effects of drug-induced parkinsonism and tardive dyskinesia, binds to the D4 receptor with an affinity 10 times higher than to the D2 and D3 receptors. This may explain clozapine's atypical properties. Here we report the existence of at least three polymorphic variations in the coding sequence of the human D4 receptor. A 48-base-pair sequence in the putative third cytoplasmic loop of this receptor exists either as a direct-repeat sequence (D4.2), as a fourfold repeat (D4.4) or as a sevenfold repeat (D4.7). Two more variant alleles were detected in humans. Expression of the complementary DNA for the three cloned receptor variants showed different properties for the long form (D4.7) and the shorter forms (D4.2, D4.4) with respect to clozapine and spiperone binding. To our knowledge, this is the first report of a receptor in the catecholamine receptor family that displays polymorphic variation in the human population. Such variation among humans may underlie individual differences in susceptibility to neuropsychiatric disease and in responsiveness to antipsychotic medication.     

Cloning and characterization of a vasopressin V2 receptor and possible link to nephrogenic diabetes insipidus.

The antidiuretic effect of arginine vasopressin (AVP) is mediated by renal-type (V2) receptors linked to adenylyl cyclase. We report here the cloning of the rat kidney V2 AVP receptor complementary DNA that encodes a 370-amino-acid protein with a transmembrane topography characteristic of G protein-coupled receptors, and with similarity to the V1a (hepatic) AVP receptor in its seven membrane-spanning domains. Expression of the cloned cDNA in mammalian cells showed specific ligand binding and activity characteristic of the native V2 AVP receptor. The receptor messenger RNA is detected only in the kidney. The human V2 receptor gene has been localized to the long arm of the X chromosome close to the locus for nephrogenic diabetes insipidus, an X-linked recessive disorder characterized by renal resistance to the antidiuretic action of AVP.     

System Approach to the Integration of Military and Civilian Productions in China

The author uses system analysis to provide system thinkings of the deepening reform of the management of defence science, technology and industry (DSTI) and investigate the system definition of DSTI, the system reform target, system operational mechanism, institutional structure, coordination and control functions and the orientation of conversion in China.     

Some Equivalence Transform Methods for Simulating Models in Control Systems

In this paper two classes of equivalence transform methods for solving ordinary differential equations are proposed. One class of method is the equivalence integral transform method for special differential algebraic problems. The advantage of this class of method is such that the amount of work calculating one integration with parameters becomes that of two interpolations, when the system of nonlinear equations is solved on the right hand side function. The other class of method is the equivalence substitution method tor avoiding calculating derivative on the right hand side function. In order to avoid calculation derivatives, two equivalence substitution methods are proposed here. The application instances of some special effect of the equivalence substitution methods are given.     

Potential aldose reductase inhibitors: 1,2,4-triazolidine-3,5-diones and 2-(3,4,5-trimethoxybenzoyl)-4,4-diethyl-3,5-isoxazolidinedione .

1,2,4-Triazolidine-3,5-diones and the 3,5-isoxazolidinedione were observed to be potent inhibitors of rat lens aldose reductase activity. In vivo in streptozotocin-diabetic rats, selected agents at 20 mg/kg/day, orally for 21 days reduced significantly the sorbitol levels of rbc, lens and sciatic nerves, suggesting that these derivatives may have some usefulness to treat clinical complications of diabetes mellitus.     

Eine im Alkalischen wirksame Monophosphoesterase aus Hefe

Summary The authors describe a monophosphoesterase isolated from yeast which acts strongly on sodium phenolphthaleinphosphate, phenolphosphate, and-glycerophosphate in an alkaline medium (p _H 8,5–9,1). The enzyme does not need magnesium ions for its activity.