ANTIVIRAL ACTIVITY OF CULTURED BLUE-GREEN ALGAE (CYANOPHYTA)1

Lipophilic and hydrophilic extracts from approximately 600 strains of cultured cyanophytes, representing some 300 species, were examined for antiviral activity against three pathogenic viruses. Approximately 10% of the cultures produced substances that caused significant reduction in cytopathic effect normally associated with viral infection. The screening program identified the order Chroococcales as commonly producing antiviral agents.     

Order of bovine DRB3, DYA,and PRL determined by sperm typing

The order and recombination fractions () between the bovine major histocompatibility complex DRB3, DYA, and prolactin (PRL) genes were determined by typing of 254 sperm from a triply heterozygous bull. A recently developed method, primer extension preamplification (PEP), was used to amplify the bovine sperm genome prior to amplification of specific loci by the polymerase chain reaction (PCR). At least 28 copies of the DRB3, PRL, or DYA gene were obtained from 50 cycles of PEP. For sperm typing, alleles of each locus were discriminated by restriction endonuclease cleavage of PCR products and polyacrylamide gel electrophoresis of the restriction fragments. The most likely gene order is PRL-DRB3-DYA, with =0.025 (±0.012) and =0.150 (±0.024), respectively. The odds are 128:1 in favor of this order in comparison with the second most likely order DRB3-PRL-DYA. Our results demonstrate the power of sperm typing in concert with PEP for multilocus gene mapping.     

Iron supplementation moderates but does not cure the Belgrade anemia

Belgrade rats inherit microcytic, hypochromic anemia as an autosomalrecessive trait (gene symbol b). Erythrocytes and tissue are iron deficientin the face of elevated TIBC (total iron binding capacity) and percent ironsaturation; iron injections increased the number of erythrocytes but theirappearance remained abnormal. We have investigated iron supplements toimprove husbandry of b/b rats and to learn more about the underlying defectand its tissue distribution. Weekly IM (intramuscular) injections ofiron–dextran (Imferon at 30 mg kg) improved the anemia but did not alter thered cell morphology. Certain diets also improved the health of b/b rats whencompared to standard rat chows by the criteria of weight, survival toadulthood, hematology and reproduction. The critical nutritional factorturned out to be iron bioavailability, with ferrous iron added to the dietimproving the health of Belgrade rats without affecting the underlyingerythroid defect. Tissue iron measurements after dietary or parenteralsupplementation confirmed the iron deficient status of untreated b/b rats andestablished that dietary ferrous iron partially relieved this deficiency,with injections leading to greater amounts of tissue iron. Serum iron andTIBC were also found to be elevated in untreated b/b rats, with dietarysupplementation decreasing but not eliminating the elevation in TIBC. Thesestudies indicate that iron supplements can improve the health of b/b ratswithout altering the underlying defect and also suggest that the mutationcould alter iron uptake in the GI (gastrointestinal) tract.     

Hypothesis--a chemical mechanism for the biosynthesis of ATP involving ion-exchange reactions

Dissociation constants for Mg . ATP were determined by displacing ATP from Dowex-1 resin with magnesium. These constants were then used to analyze the kinetics of yeast mitochondrial ATPase, in terms of the concentrations of free magnesium and free ATP, at a series of pH values. Both Mg . ATP and hydroxide ions were found to compete with the binding of ATP to the enzyme. These results were interpreted, in terms of an ion-exchange model, to mean that the synthesis of ATP may require the utilization of both magnesium and hydroxide ions for the dissociation of ATP from the enzyme as Mg . ATP. The concentrations of Mg and hydroxide required to compete with ATP were both found to be about three orders of magnitude greater than those required to form products, indicating that magnesium and hydroxide ions can contribute about 8 kcal of energy when ATP is synthesized.     

Thermal behavior and elastic properties of phospholipid bilayers under the effect of a synthetic flavonoid derivative, LEW-10.

We have investigated the effect on phospholipidic bilayers of LEW-10, a synthetic flavonoid, derivative of diosmin. Two optical techniques, Quasi-elastic Light Scattering (QLS) and Fourier Transform Infrared Spectroscopy (FT-IR) were used. The results show that in the presence of LEW-10, the phase transition of the bilayers is lowered and that the elastic modulus is decreased. The FT-IR results indicate interactions in the aqueous interface regions of the bilayers. We also discuss LEW-10 comparatively with another derivative, LEW-7/S1, whose effect has been previously studied.     

Purification of a histamine H3 receptor negatively coupled to phosphoinositide turnover in the human gastric cell line HGT1.

The histamine H3 receptor agonist (R)alpha-methylhistamine (MeHA) inhibited, in a nanomolar range, basal and carbachol-stimulated inositol phosphate formation in the human gastric tumoral cell line HGT1-clone 6. The inhibition was reversed by micromolar concentrations of the histamine H3 receptor antagonist thioperamide and was sensitive to cholera or pertussis toxin treatment. Using [3H]N alpha-MeHA as specific tracer, high affinity binding sites were demonstrated with a Bmax of 54 +/- 3 fmol/mg of protein and a KD of either 0.61 +/- 0.04 or 2.2 +/- 0.4 nM, in the absence or presence of 50 microM GTP[gamma]S, respectively. The binding sites were solubilized by Triton X-100 and prepurified by gel chromatography. They were separated from the histamine H2 receptor sites by filtration through Sepharose-famotidine and finally retained on Sepharose-thioperamide. The purified sites concentrated in one single silver-stained protein band of 70 kDa in SDS-polyacrylamide gel electrophoresis. They specifically bound [3H]N alpha-MeHA with a KD of 1.6 +/- 0.1 nM and a Bmax of 12,000 +/- 750 pmol/mg of protein. This corresponds to a 90,225-fold purification over cell lysate and a purity degree of 84%. Binding was competitively displaced by N alpha-MeHA (IC50 = 5.8 +/- 0.7 nM), (R) alpha-MeHA (IC50 = 9 +/- 1 nM), and thioperamide (IC50 = 85 +/- 10 nM), but not by famotidine (H2 antagonist) or by mepyramine (H1 antagonist). These findings provide the first evidence for solubilization, purification, and molecular mass characterization of the histamine H3 receptor protein and for the negative coupling of this receptor phosphatidylinositol turnover through a so far unidentified G protein.