Biochemical analysis of BmNPV attachment toBombyx mori BmN-4 cells

Binding characteristics ofBombyx mori nuclear polyhedrosis virus (BmNPV) toB. mori BmN-4 cells was determined. The cells had a single class of BmNPV-binding sites and displayed a low binding capacity for BmNPV in the range of 70 sites per cell. The biochemical nature of BmNPV-binding sites on the cell surface was identified. Treatment of BmN-4 cells with protease, wheat germ agglutinin, metabolic inhibitors, or lysosomotropic agents reduced BmNPV binding to BmN-4 cells, whereas treatment with phospholipase C showed no effect on virus binding. These results indicate that the structure of the binding site moiety is a protein-oligosaccharide complex.     

Embryonic evidence uncovers convergent origins of laryngeal echolocation in bats

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Real-time detection of Fe·EDTA/H2O2-induced DNA cleavage by linear dichroism

The conditions for the measurement of linear dichroism (LD) can be adjusted so as to solely reflect the length and the flexibility of DNA. The real-time detection of the EDTA·Fe²⁺-induced oxidative cleavage of double-stranded native and synthetic DNAs was performed using LD. The decrease in the magnitude of the LD at 260 nm, which reflects an increase in the flexibility and a decrease in the length of the DNA, can be described by the sum of two or three exponential curves in relation to the EDTA·Fe²⁺ concentration. The fast component was assigned to the cleavage of one of the double strands, inducing an increase in the flexibility, while the other slower component was assigned to the cleavage of the double strand, resulting in the shortening of DNA. The decrease in the magnitude of the LD of poly[d(A-T)₂] was similar to that of poly[d(I-C)₂], while that of poly[d(G-C)₂] was found to be the slowest, indicating that the resistance of poly[d(G-C)₂] against the Fenton-type reagent was the strongest. This observation suggests that the amine group in the minor groove of the double helix may play an important role in slowing the EDTA·Fe²⁺-induced oxidative cleavage.     

Recent development of highly sensitive protease assay methods: Signal amplification through enzyme cascades

Proteases are involved in almost all biological processes, and therefore, aberrant activity of many of these enzymes is an important indicator of disease. Various methods have been developed to analyze protease activity, among which, protease assays based on resonance energy transfer are currently used most widely. However, quantitative methods with relatively higher sensitivity are needed, especially for disease diagnosis at early stages. One of the strategies to achieve higher sensitivity is to implement signal amplification of the protease activity. In this review, we briefly summarize the protease assay methods based on resonance energy transfer, and then elaborate the efforts to develop sensitive protease assays through signal amplification by using enzyme cascades.     

Photophysical properties of dibenzofluorescein and the presence of its tautomers or prototropic forms in organic solvents.

The UV/Vis absorption and fluorescence properties of dibenzofluorescein (DBFL) in organic solvents were measured and used to shed light on the possible presence of its tautomers or various prototropic forms. DBFL in aprotic solvents mainly exists in two tautomeric forms, viz. quinoid and lactone, but neither are efficiently fluorescent. In protic solvents, such as methanol and ethanol, both the monoanion and neutral quinoid are present and showed the highest fluorescence quantum yield. In contrast, DBFL is fully dissociated to the monoanion and dianion in deionized water.     

Evolutionary Origin of GnIH and NPFF in Chordates: Insights from Novel Amphioxus RFamide Peptides

Gonadotropin-inhibitory hormone (GnIH) is a newly identified hypothalamic neuropeptide that inhibits pituitary hormone secretion in vertebrates. GnIH has an LPXRFamide (X = L or Q) motif at the C-terminal in representative species of gnathostomes. On the other hand, neuropeptide FF (NPFF), a neuropeptide characterized as a pain-modulatory neuropeptide, in vertebrates has a PQRFamide motif similar to the C-terminal of GnIH, suggesting that GnIH and NPFF have diverged from a common ancestor. Because GnIH and NPFF belong to the RFamide peptide family in vertebrates, protochordate RFamide peptides may provide important insights into the evolutionary origin of GnIH and NPFF. In this study, we identified a novel gene encoding RFamide peptides and two genes of their putative receptors in the amphioxus Branchiostoma japonicum. Molecular phylogenetic analysis and synteny analysis indicated that these genes are closely related to the genes of GnIH and NPFF and their receptors of vertebrates. We further identified mature RFamide peptides and their receptors in protochordates. The identified amphioxus RFamide peptides inhibited forskolin induced cAMP signaling in the COS-7 cells with one of the identified amphioxus RFamide peptide receptors expressed. These results indicate that the identified protochordate RFamide peptide gene is a common ancestral form of GnIH and NPFF genes, suggesting that the origin of GnIH and NPFF may date back to the time of the emergence of early chordates. GnIH gene and NPFF gene may have diverged by whole-genome duplication in the course of vertebrate evolution.     

Inhibition of HIV replication by amino-sugar derivatives

The plant alkaloids castanospermine, dihydroxymethyldihydroxypyrrolidine and deoxynojirimycin have recently been shown to have potential anti-HIV activity [(1987) Proc. Natl. Acad. Sci. USA 84, 8120-8124; (1987) Nature 330, 74-77; (1987) Lancet i, 1025-1026]. They are thought to act by inhibiting alpha-glucosidase I, an enzyme involved in the processing of N-linked oligosaccharides on glycoproteins. We report here the relative efficacy of a spectrum of amino-sugar derivatives as inhibition of HIV cytopathicity. Several alpha-glucosidase inhibitors and alpha-fucosidase inhibitors were found to be active at concentrations which were non-cytotoxic.