Fluctuation of algal alkaline phosphatase activity and the possible mechanisms of hydrolysis of dissolved organic phosphorus in Lake Barato

For freshwater cyanobacteria, the autofluorescence of phycocyanin is quite high while the in vivo fluorescence (IVF) yield of chlorophyll-a is relatively low, apparently because of low chlorophyll concentrations associated with photosystem II. In eucaryotic phytoplankton, even those with phycobili-protein accessory pigments (e.g. some cryptophytes), the opposite is true. Thus, an IVF ratio which relates phycocyanin to chlorophyll-a signals could be a good index of relative cyanobacterial abundance in the field. Spectrofluorometric scans of whole cells from laboratory cultures indicated that the ratio Em₆₆₀ @ Ex₆₃₀/Em₆₈₀ @ Ex₄₃₀ could be a very sensitive cyanobacterial indicator. Tandem flowthrough fluorometers were then fitted with the appropriate interference filters and their discriminatory power was evaluated with mixtures of cyanobacterial and eucaryotic phytoplankton. Although subject to many of the constraints of other IVF assays, tandem fluorometry should be particularly appropriate for real-time mapping of the relative spatial and temporal distributions of broad phytoplankton taxa in continuous vertical of horizontal profiles in lakes.     

Characterization of two types of histone H2B genes from macronuclei of Tetrahymena thermophila.

Two histone H2B gene clones were isolated from macronuclei of Tetrahymena thermophila. Nucleotide sequences of the two clones were highly homologous within the coding region but not in the noncoding region. Comparison of the deduced amino acid sequences between the two clones showed three differences in a total of 121 amino acids. Each of the two clones contained a TAA triplet within the coding region, which appeared to code for a glutamine residue. To demonstrate the existence of histone mRNA containing UAA triplet, nuclease P1 protection mapping using total cellular RNA and nucleotide sequencing of primer extension products were carried out. The results clearly indicated that two cloned histone H2B genes were transcribed, giving rise to the major histone H2B mRNAs with a UAA triplet sequence in frame. The tentative 5'- and 3'-ends of histone H2B mRNAs were determined.     

Molecular cloning and nucleotide sequencing of oxyR, the positive regulatory gene of a regulon for an adaptive response to oxidative stress in Escherichia coli: homologies between OxyR protein and a family of bacterial activator proteins

Summary Treatment of Escherichia coli and Salmonella typhimurium cells with a low dose of hydrogen peroxide induces expression of a large number of genes, and confers resistance to oxidative stresses. The oxyR gene encodes a positive regulatory protein for a subset of these genes involved in the defense against oxidative damage. We cloned a DNA fragment that contains the E. coli oxyR region on a plasmid vector, and analyzed the nucleotide sequence of the gene. The amino acid sequence of OxyR protein, deduced from the nucleotide sequence, shows a high degree of homology to the sequences of a number of bacterial activator proteins including LysR, cysB, IlvY, MetR and NodD. The product of the oxyR gene identified by the maxicell procedure was a 34 kDa protein, which agrees with the size predicted from the nucleotide sequence of the gene.     

Developmental changes in the effects of carbachol and morphine on cGMP contents of plasma, heart, and lung of mice

It is considered that carbachol increases plasma cGMP levels by acting on muscarinic receptors and morphine increases these levels by acting on opioid receptors, followed by stimulation of muscarinic receptors. We investigated the ability of carbachol and morphine to increase cGMP contents of plasma, heart, and lung and the guanylate cyclase activity of heart and lung homogenate in 1-, 2-, 3-, and 7-week-old mice. The increase in plasma cGMP levels induced by carbachol showed a peak at 2 and 3 weeks of age. The basal cGMP contents in heart and lung and their rise induced by carbachol, as well as the guanylate cyclase activity of these organs, were decreased in 7-week-old mice. The effects of morphine on the cGMP contents showed a similar developmental change, except for no effect in 1-week-old mice. These changes in the effects of carbachol and morphine may be the result of developmental changes of the muscarinic receptor--guanylate cyclase system and opioid receptors.     

A comparative 1H NMR study of mouse alpha(1-53) and beta(2-53) epidermal growth factors

The three-dimensional structure of the mouse epidermal growth factor (EGF) in solution was studied by comparison of the 1H NMR spectra of alpha EGF (1-53) and beta EGF (2-53, des-asparaginyl 1 form). Using pH dependence of chemical shifts and a two-dimensional difference spectrum, the effect of the N-terminal deletion was investigated based on the complete assignment of the proton resonances. The affected residues were all found to be located exactly in the triple-stranded, beta-sheet core in the N-terminal domain of the EGF molecule.     

Combination therapy of radiation and Sizofiran (SPG) on the tumor growth and metastasis on squamous-cell carcinoma NR-S1 in syngeneic C3H/He mice

The efficacy of Sizofiran(SPG), a highly purified -1,3-D-glucan from the culture broth of a basidiomycetesSchizophyllum commune Fries, in combination with local irradiation was investigated using squamous-cell carcinoma NR-S1 and syngeneic hosts of OH/He mice. NR-S1 tumor was implanted sc in the thigh of C3H/He mice. When tumor grew to 4 mm in diameter, the local irradiation of 55 Gy was delivered. SPG was injected im at a dose of 5 mg/kg. When SPG was administered after irradiation, remarkable inhibition of tumor growth was observed in comparison with the radiation alone group. Furthermore, the combination effect of radiation and active immunotherapy using mitomycin C-treated NR-S1 cells as vaccine was examined. When radiotherapy and active immunotherapy were combined with SPG, suppression of tumor growth was observed from an early stage in comparison with the group which was not administered SPG. SPG also inhibited the pulmonary metastasis of NR-S1 tumor after radiotherapy.     

Carbohydrate structures of acetylcholine receptor from Torpedo californica and distribution of oligosaccharides among the subunits

The structure of carbohydrates in acetylcholine receptor (AChR) from Torpedo californica is reported. Oligosaccharides released quantitatively from the whole molecule by N-oligosaccharide glycopeptidase digestion were fractionated by thin-layer chromatography and further purified by high-performance liquid chromatography. We show that more than 70% of the total oligosaccharide chains in Torpedo AChR are of the high-mannose type with the structures (Man)8(GlcNAc)2 and (Man)9(GlcNAc)2. The structure of these oligosaccharides were determined by proton nuclear magnetic resonance spectroscopy. These two types of oligosaccharides were shown to be distributed different proportions in all subunits of Torpedo AChR. We also show that several kinds of complex-type oligosaccharides comprising the rest of the carbohydrate in the protein exist mainly in the gamma and delta subunits. The structure of the carbohydrate moiety that is distributed on the four subunits of AChR was also examined by susceptibility to endo-beta-N-acetylglucosaminidase and sialidase and by binding affinity to lectins, e.g. concanavalin A, leucoagglutinating phytohemagglutinin, and wheat germ agglutinin.