Comparison of two scores for allocating resources to doctors in deprived areas.

Current proposals in the general practitioner contract include additional payments to doctors working among deprived populations. The underprivileged area score will be used to identify local authority wards with the greatest levels of deprivation, thus acting as the basis for distributing considerable resources. Two methods of identifying deprived populations--the underprivileged area score and the material deprivation score--were compared to determine whether they result in similar allocation of resources to regions. Financial allocations to regions based on figures derived from the contract differed considerably if the material deprivation score was used instead of the underprivileged area score: Northern and Mersey regions gained over 50% of their allocation whereas East Anglia, Oxford, and South West Thames regions lost more than 30% of theirs. Such differences have considerable implications for doctors working among deprived populations as up to 60m pounds each year might be distributed by these payments.     

Cloning of genes governing the deoxysugar portion of the erythromycin biosynthesis pathway in Saccharopolyspora erythraea (Streptomyces erythreus).

Genes that govern the formation of deoxysugars or their attachment to erythronolide B and 3 alpha-mycarosyl erythronolide B, intermediates of the biosynthesis of the 14-membered macrolide antibiotic erythromycin, were cloned from Saccharopolyspora erythraea (formerly Streptomyces erythreus). Segments of DNA that complement the eryB25, eryB26, eryB46, eryC1-60, and eryD24 mutations blocking the formation of erythronolide B or 3 alpha-mycarosyl erythronolide B, when cloned in Escherichia coli-Streptomyces shuttle cosmids or plasmid vectors that can transform S. erythraea, were located in a ca. 18-kilobase-pair region upstream of the erythromycin resistance (ermE) gene. The eryC1 gene lies just to the 5' side of ermE, and one (or possibly two) eryB gene is approximately 12 kilobase pairs farther upstream. Another eryB gene may be in the same region, while an additional eryB mutation appears to be located elsewhere. The eryD gene lies between the eryB and eryC1 genes and may regulate their function on the basis of the phenotype of an EryD- mutant.     

Role of purine metabolism in thidiazuron-induced somatic embryogenesis of geranium (Pelargonium × hortorum) hypocotyl cultures

Somatic embryogenesis in geranium ( Pelargonium × hortorum Bailey cv. Scarlet Orbit Improved) was achieved by culturing hypocotyl sections on Murashige and Skoog (1962) (MS) medium containing 10 μ M thidiazuron (TDZ) (induction medium) for 3 days and subsequently transferring the sections onto a basal medium lacking any plant growth regulators (expression medium). Addition of the purine analogue 2.6-diaminopurine (DAP) to the somatic embryo induction medium completely inhibited the embryogenic response as well as chlorophyll accumulation without affecting enlargement of the treated tissues. Addition of 20 μ M adenine sulphate to the expression medium, i.e during embryo growth and development phase, completely reversed the DAP-induced inhibition of the embryogenic response while addition during the induction phase caused only a 50% reversal of the inhibition. Analysis of endogenous levels of plant growth substances indicated that TDZ alone elevated the levels of auxins, cy-tokinins and abscisic acid while the presence of DAP during the induction phase caused a further increase in the levels of adenine and adenosine. These findings indicate a possible critical role for purines in embryogenesis from geranium hypocotyl tissues. However, the conversion of cytokinin bases to their corresponding nucleotide forms was not evident as the levels of isopentenyl adenine and zeatin increased during the second day of culture.     

The Effects of Surfactants on Lipase-Catalysed Hydrolysis of Esters: Activities and Stereoselectivity

The effect of surfactants on the hydrolysis of prochiral and chiral substrates by crude and purified porcine pancreatic lipase (PPL, EC 3.1.1.3)) has been studied. Rather than accelerating the reactions, surfactants slowed down (“inhibited”) the reactions relative to the rate in the absence of surfactant. Surfactants varied in the extent to which the reaction was inhibited. With the crude enzyme there was a correlation between degree of inhibition and the optical purity of the product of hydrolysis of an achiral diester substrate 1. There was no special effect associated with use of surfactants in the concentration range corresponding to critical micelle formation, nor was there any increase in rate of reaction when stable emulsions were formed by using mixtures of surfactants to generate an appropriate hydrophile-lipophile (HLB) balance. A study of the effect of sodium dodecyl sulphate (SDS) on the hydrolysis of the diester 1 by crude PPL showed that the rate of the reaction steadily decreased with increasing surfactant concentration, but that the optical purity of the product first fell and then rose gain, an effect attributed to the differential denaturing action of the surfactant on at least three hydrolytic enzymes. In general, there would seem to be no advantage to be gained from the use of surfactants in the hydrolysis by PPL of compounds of low water solubility; the use of an immiscible co-solvent is more effective.     

Herpes simplex virus glycoprotein K is known to influence fusion of infected cells, yet is not on the cell surface.

Syncytial mutants of herpes simplex virus (HSV) cause extensive fusion of cultured cells, whereas wild-type HSV primarily causes cell rounding and aggregation. A large fraction of syncytial viruses contain mutations in the UL53 gene, which encodes glycoprotein K (gK). Previously, we demonstrated that wild-type and syncytial forms of gK are expressed at similar levels and possess identical electrophoretic mobilities. Using immunofluorescence, we show that gK is not transported to the surfaces of cells infected with either wild-type or syncytial HSV. Instead, gK accumulates in the perinuclear and nuclear membranes of cells. This finding is in contrast to the behavior of all other HSV glycoproteins described to date, which reach the cell surface. When gK was expressed in the absence of other HSV proteins, using a recombinant adenovirus vector, a similar perinuclear and nuclear pattern was observed. In addition, gK remained sensitive to endoglycosidase H, consistent with the hypothesis that gK does not reach the Golgi apparatus and is retained in the endoplasmic reticulum and nuclear envelope. Therefore, although gK mutations promote fusion between the surface membranes of HSV-infected cells, the glycoprotein does not reach the plasma membrane and, thus, must influence fusion indirectly.     

Development and characterisation of a line of bread wheat,Triticum aestivum,which lacks the short-arm satellite of chromosome 1B and the Gli-B1 locus

Summary About 360 offspring of a tri-parental cross were screened by gel electrophoresis and unexpectedly one of them did not contain chromosome 1B -gliadins derived from either of the primary parents. A line disomic for the -gliadin null was developed from the surviving embryo half of the unique grain. Two dimensional electrophoresis revealed that all the storage protein genes at Gli-B1, coding for -gliadins, -gliadins and low-molecular-weight subunits of glutenin as well as the -gliadin, were not expressed. The nuclei of dividing root-tip cells were shown by light microscopy to lack the normal short-arm satellites of chromosome 1B, indicating that the genes for the missing storage proteins had been lost through a terminal deletion. Using a radioactive ribosomal RNA probe, the deficient 1B chromosomes were shown to contain ribosomal RNA genes demonstrating that at least two-thirds of the short arm was still present. Examination of serial sections of chromosome 1B at metaphase by low-power electron microscopy showed that the point of scission of this chromosome was within the secondary constriction where the ribosomal RNA genes are located. The Gli-B1 locus must therefore be carried on the short-arm satellite. Transmission of the deficient chromosome from female gametes to progeny was normal (i.e., about 50%) but from pollen it was poor (8.8%). Recombination mapping indicated that the distance from the ribosomal RNA genes (Nor1) to Glu-B1 was 22 cM, equivalent to 13 cM from Nor1 to the centromere.     

Isolation and characterization of plasma membrane-associated cortical granules from sea urchin eggs

Cortical granules, which are specialized secretory organelles found in ova of many organisms, have been isolated from the eggs of the sea urchins Arbacia punctulata and Strongylocentrtus pupuratus by a simple, rapid procedure. Electron micropscope examination of cortical granules prepared by this procedure reveals that they are tightly attached to large segments of the plasma membrane and its associated vitelline layer. Further evidence that he cortical granules were associated with these cell surface layers was obtained by (125)I-labeling techniques. The cortical granule preparations were found to be rich in proteoesterase, which was purified 32-fold over that detected in a crude homogenate. Similarly, the specific radioactivity of a (125)I-labeled, surface glycoprotein was increased 40-fold. These facts, coupled with electron microscope observations, indicate the isolation procedure yields a preparation in which both the cortical granules and the plasma membrane-vitelline layer are purified to the same extent. Gel electrophoresis of the membrane-associated cortical granule preparation reveals the presence of at least eight polypeptides. The major polypeptide, which is a glycotprotein of apparent mol wt of 100,000, contains most of the radioactivity introduced by (125)I-labeling of the intact eggs. Lysis of the cortical granules is observed under hypotonic conditions, or under isotonic conditions if Ca(2+) ion is present. When lysis is under isotonic conditions is induced by addition of Ca(2+) ion, the electron-dense contents of the granules remain insoluble. In contrast, hypotonic lysis results in release of the contents of the granule in a soluble form. However, in both cases the (125)I-labeled glycoprotein remains insoluble, presumably because it is a component of either the plasma membrane or the vitelline layer. All these findings indicate that, using this purified preparation, it should be possible to carry out in vitro studies to better define some of the initial, surface-related events observed in vivo upon fertilization.