Characterization of the chicken oocyte receptor for low and very low density lipoproteins

The chicken oocyte receptor for low and very low density lipoproteins has been identified and characterized. Receptor activity present in octyl-beta-D-glucoside extracts of oocyte membranes was measured by a solid phase filtration assay, and the receptor was visualized by ligand blotting. The protein had an apparent Mr of 95,000 in sodium dodecyl sulfate-polyacrylamide gels under nonreducing conditions and exhibited high affinity for apolipoprotein B-containing lipoproteins, but not for high density lipoproteins or lipoproteins in which lysine residues had been reductively methylated. Binding of lipoproteins was sensitive to EDTA, suramin, and treatment with Pronase. In these aspects, the avian oocyte system was analogous to the mammalian low density lipoprotein receptor in somatic cells. Furthermore, a structural relationship between the mammalian and avian receptors was revealed by immunoblotting: polyclonal antibodies directed against the purified bovine low density lipoprotein receptor reacted selectively with the 95-kDa chicken receptor present in crude oocyte membrane extracts.     

GC-MS identification of GA20-13-O-glucoside formed from GA20 in normal plants and dwarf-1 mutants ofZea mays L.

After feeding GA₂₀ to excised seedlings ofZea mays L. normals (N) and dwarf-1 mutants (d1), GA₂₀-13-O-glucoside (9) was identified by HPLC and by GC-MS of its permethylated derivative. The glucosylation rate of GA₂₀ was found to be higher in the dwarf-1 mutant (26%) than in the normal plant (3.6%). This article includes a GC-MS study in which diagnostic fragments from the spectra of permethylated synthetic GA glucosides have been selected that proved to be useful for the identification of permethylated GA glucosides.     

Sexual dimorphism in neuronal projections from the antennae of silk moths (Bombyx mori,Antheraea polyphemus) and the gypsy moth (Lymantria dispar)

Summary The antennal lobe of both sexes of the silk moth Bombyx mori contains 55–60 ventrally located antennal glomeruli; in addition, that of the male contains a dorsal macroglomerular complex (MGC). A group of identifiable glomeruli consisting of two lateral large glomeruli (LLG) and four medial small glomeruli (MSG) is present in both sexes, but the LLG are greatly enlarged in the female. A MGC is also present in the male gypsy moth Lymantria dispar and male giant silk moth Antheraea polyphemus. The MGC in all of these species is organized into 3–4 distinct levels of glomeruli. Antennal sensory fibers were stained by cobalt backfills in B. mori, A. polyphemus, and L. dispar. Most fibers stained from cut long hairs (sensilla trichodea) projected to MGC in males and LLG in both sexes of B. mori. The distribution of fibers in the MGC of B. mori was topographically biased in that a majority of fibers from anterior branches projected medially in MGC while most fibers from posterior branches projected laterally or anteriorly. Terminal arborizations of single fibers were each restricted to a single glomerular level of the MGC. Fibers projecting to the posterior antennal center were frequently stained in cut-hair and control preparations, apparently by uptake of cobalt through intact sensilla on flagellar branches.     

The untranslated leader of nuclear COX4 gene of Saccharomyces cerevisiae contains an intron.

The nuclear gene for subunit IV of cytochrome oxidase (COX4) in Saccharomyces cerevisiae contains a 342 bp intron which is contained entirely within the 5' leader of the message. Splicing of the intron results in removal of several small open reading frames; subsequently, the COX4 AUG becomes the 5' proximal initiation codon. A strain with an rna2- mutation fails to splice mRNA efficiently at restrictive temperature and was used to map the intron splice junctions by RNase protection. Two major mRNA initiation sites were mapped by primer extension of synthetic oligodeoxynucleotides. The splice junctions and internal TACTAAC box conform to consensus sequences previously determined from other yeast introns. One gene for subunit V of cytochrome oxidase (COX5b) has also been shown to contain an intron. The significance of introns in two nuclear genes encoding subunits of cytochrome oxidase is discussed.     

Cost effectiveness of biofeedback and behavioral medicine treatments: a review of the literature

This paper reviews multicomponent behavioral medicine studies that contain cost-effectiveness and or cost-benefit data relevant to the field of biofeedback and relaxation training, primarily when assisted by biofeedback, with or without stress management, in the treatment of psychosomatic illness and pain. A model for evaluating biofeedback treatment is presented. Cost-effectiveness data concerning reduction in physician visits and/or medication use, decrease in medical care costs to patients, reduction in hospital stays and rehospitalization, reduction of mortality, and enhanced quality of life are reviewed. Evidence suggests that multicomponent behavioral medicine treatments are cost-effective on all dimensions reviewed. Cost/benefit ratios range between 1:2 and 1:5, with a median of 1:4. Evidence that could increase the cost effectiveness of biofeedback is reviewed.     

Regulation of intracellular pH by a neuronal homolog of the erythrocyte anion exchanger

We have isolated AE3, a novel gene expressed primarily in brain neurons and in heart. The predicted AE3 polypeptide shares a high degree of identity with the anion exchange and cytoskeletal binding domains of the erythrocyte band 3 protein. Expression of AE3 cDNA in COS cells leads to chronic cytoplasmic acidification and to chloride- and bicarbonate-dependent changes in intracellular pH, confirming that this gene product is an anion exchanger. Characterization of an AE3 mutant lacking the NH2-terminal 645 amino acids demonstrates that the COOH-terminal half of the polypeptide is both necessary and sufficient for correct insertion into the plasma membrane and for anion exchange activity. The NH2-terminal domain may play a role in regulating the activity of the exchanger and may be involved in the structural organization of the cytoskeleton in neurons.     

Genetic and Biochemical Characterization of Mutations Affecting the Ability of the Yeast Pachysolen tannophilus To Metabolize d-Xylose

Induced mutants, selected for their defective growth on d-xylose while retaining the ability to grow normally on d-glucose, were studied in Pachysolen tannophilus, a yeast capable of converting d-xylose to ethanol. Fourteen of the mutations were found to occur at nine distinct loci, and data indicated that many more loci remain to be detected. Most of the mutations were pleiotropic in character, and the expression of some of them was much affected by nutritional conditions and by genetic background. Mutations at several loci resulted in poor growth on at least one compound that was either an intermediate of the tricarboxylic acid cycle, succinate or alpha-ketoglutarate, or on compounds metabolizable via this cycle, ethanol or glycerol. An initial biochemical characterization of the mutants was undertaken. Analysis for xylose reductase, xylitol dehydrogenase, and xylulose kinase activity showed that one or more of these activities was affected in 12 of 13 mutants. However, drastic reduction in activity of a single enzyme was confined to that of xylitol dehydrogenase by mutations at three different loci and to that of d-xylose reductase by mutation at another locus. Growth of these latter four mutants was normal on all carbon sources tested that were not five-carbon sugars.     

The effect of ferricyanide with iodoacetate in calcium-free solution on passive cation permeability in human red blood cells: comparison with the Gardos-effect and with the influence of PCMBS on passive cation permeability

Freshly prepared human red blood cells incubated with 5 mM ferricyanide, 0.2 mM iodoacetate and 2 mM adenosine in the presence of 5 mM EGTA demonstrate comparable increases in Na+ and K+ permeability (ferricyanide effect). This effect is unrelated to the Ca2+-activated K+ channel (Gardos effect) since influx of Ca2+ from outside the cell is excluded. Also this effect is different from the non-specific Na+ and K+ permeability change elicited by PCMBS. These differences become obvious by using various reagents. For example, A23187 and quinidine exert opposite effects in Gardos and ferricyanide experiments, where A23187 and atebrin react oppositely in the latter and in PCMBS experiments. The ferricyanide effect described here does not involve formation of nonspecific channels. The change in Na+ permeability separately from K+ permeability under certain circumstances suggests a more specific effect.     

Histochemical and microbiochemical demonstration of reduced pyruvate kinase activity in thioacetamide-induced neoplastic nodules of rat liver

A new method for the histochemical demonstration of pyruvate kinase (PK) activity was developed using a semi-permeable membrane and ATP-dependent phosphorylation of glucose coupled with tetrazolium reduction via glucose-6-phosphate dehydrogenase (G6PD) in order to investigate normal liver tissue and neoplastic hepatic nodules induced by thioacetamide (TAA). A series of control reactions and comparison with microbiochemical analysis of microdissected lyophilised material were used to determine the specificity of the reaction. In agreement with earlier reports, an activity gradient in control liver decreasing from zone 3 to zone 1 was apparent both histochemically and after biochemical analysis. Liver neoplastic nodules induced by 25 weeks dietary thioacetamide administration and characterized by increased G6PD demonstrated a clear decrease in PK activity. In contrast, epithelial cells within areas of cholangiocellular tumour development were characterized by a strong increase. Comparison of the results with immunohistochemical and biochemical data from the literature indicate that the specific histochemical method described will be of great assistance in future assessment of disease and physiological alteration in activity of this key enzyme of glycolysis.