Tyrosinase inhibitor from black rice bran

The inhibitor of tyrosinase activity in black rice bran was investigated. The methanol extract from black rice bran was re-extracted with hexane, chloroform, ethyl acetate, or water. The ethyl acetate extract had the most potent inhibition against tyrosinase activity by 80.5% at a concentration of 0.4 mg/mL. Inhibitory compound in the ethyl acetate fraction was isolated by silica gel column chromatography, and identified as protocatechuic acid methyl ester (compound 1) by GC, GC-MS, IR, and 1H and 13C NMR spectroscopy. Compound 1 inhibited 75.4% of tyrosinase activity at a concentration of 0.50 micromol/mL. ID(50) (50% inhibition dose) value of compound 1 was 0.28 micromol/mL. To study the structure-activity relationship, protocatechuic acid (2), vanillic acid (3), vanillic acid methyl ester (4), isovanillic acid (5), isovanillic acid methyl ester (6), veratric acid (7), and veratric acid methyl ester (8) were also assayed.     

Memory-blocking agents: effects on olfactory discrimination in homing salmon

Homing salmon were injected intracranially with puromycin, actinomycin D, or cycloheximide. From 4 to 7 hours after such treatment these agents markedly inhibited olfactory bulbar discrimination between home water and other natural waters, including spawning sites for other groups of salmon. At longer intervals after treatment there was a partial restoration of olfactory memory-based discrimination. The dosages of the inhibitors used could be shown to have depressed incorporation of H(3)-leucine into protein by 78 percent or of H(3)-uridine into RNA by 41 percent in the salmon brains 4 hours after intracranial injection. These findings suggest that acute blockage of RNA synthesis or protein synthesis can interfere with long-term olfactory memory in anadromous salmon, at least as this function can be analyzed by electrophysiological methods. This implies that long-term olfactory memory depends upon continued metabolism of RNA and continued protein synthesis.     

Immunogenicity of pressure inactivated Edwardsiella tarda bacterin to Anguilla japonica (Japanese eel)

Japanese eel Anguilla japonica were immunized with inactivated Edwardsiella tarda bacterin preparations (formalin-killed cells, FKC (0.4%), formalin with heat-killed cells, FHKC (0.1% and 70 degreesC for 10 min), heat-killed cells, HKC (70 degrees C for 15 min), potassium chloride-killed cells, KKC (0.6%), tannic acid-killed cells, TKC (0.9%), citric acid-killed cells, CAKC (0.9%), pressure-killed cells, PKC (600 psi for 5 min) and electric current-killed cells, ECKC (100 mA at 12 v DC for 5 sec) via intraperitoneal injection in order to develop adequate inactivating method. Immune parameters in the immunized eel were measured to compare responses to different bacterins. Generally, eel rose agglutinating antibody titer in the serum within 2 week and the maximum titer occurred at 6 weeks post immunization. Elevated and significantly higher titer was produced with the PKC of E. tarda than other bacterin preparations. An Enzyme Linked Immunosorbent Assay (ELISA), to determine specific anti-E. tarda antibody in the serum, also showed significantly higher antibody titer with PKC than the other antigen preparations. Bacteriostatic assay with serum and live E. tarda indicated significantly higher activity in the PKC-immunized fish. Immunization with PKC also showed the increased level ofphagocytosis. PKC-inactivated vaccine at an immunization dose of 10(6) cells/fish induced high protection against experimental infection. Coincident with higher immune parameters and protection in the fish immunized with the PKC bacterin strongly suggested that pressure-killing is an effective inactivating method to develop an effective vaccine against edwardsiellosis.     

Heat-shock-induced tetraploid and diploid/tetraploid mosaic in pond loach, Misgurnus anguillicaudatus

Tetraploid fish, which are considered as key resources of diploid gametes for further breeding and ploidy manipulation, can be artificially induced by inhibition of the mitotic cell division with hydrostatic pressure or temperature treatments. Although many attempts have been made to induce artificial tetraploid strains, successful establishment of viable and fertile tetraploid strains are rare. In pond loach, Misgurnus anguillicaudatus, natural tetraploid individuals are distributed in wild populations and diploid gametes from the tetraploid fish have been used for the induction of polyploid individuals, but artificially induced tetraploid strains have not been established yet. In the present study, we optimised starting timing of the heat-shock treatment (41 °C for 2 min) to inhibit a mitotic cell division in fertilised eggs of the normal diploid pond loach between 21 and 51 min after insemination at 20 °C. After the treatment, we observed external appearance of hatching larvae and flow cytometrically determined ploidy status of the resultant larvae. Although tetraploid and diploid/tetraploid mosaic larvae were obtained, the optimum timings for induction of tetraploidy varied amongst crosses. Various kinds of ploidy such as haploidy, diploidy, triploidy, pentaploidy, hexaploidy, aneuploidy and mosaic were detected in non-optimum heat-shock timings for tetraploidisation. Survivors, a tetraploid and a diploid/tetraploid mosaic male, matured at the age of 1-year-old, but they produced functional haploid spermatozoa.     

Exploring the phytoplasmas,plant pathogenic bacteria

Phytoplasmas are plant pathogenic bacteria associated with devastating damage to over 700 plant species worldwide. It is agriculturally important to identify factors involved in their pathogenicity and to discover effective measures to control phytoplasma diseases. Despite their economic importance, phytoplasmas remain the most poorly characterized plant pathogens, primarily because efforts at in vitro culture, gene delivery, and mutagenesis have been unsuccessful. However, recent molecular studies have revealed unique biological features of phytoplasmas. This review summarizes the history and recent progress in phytoplasma research, focusing on (1) the discovery of phytoplasmas, (2) molecular classification of phytoplasmas, (3) diagnosis of phytoplasma diseases, (4) reductive evolution of the genomes, (5) characteristic features of the plasmids, (6) molecular mechanisms of insect transmissibility, and (7) virulence factors involved in their unique symptoms.     

Molecular evidence that a lily-infecting strain of Tulip breaking virus from Japan is a strain of Lily mottle virus

The sequence of the 3-terminal 2074 nucleotides (nts), excluding the 3-poly (A) tail, of RNA of a potyvirus isolated from lily (Lilium Asiatic hybrid cv. Enchantment) in Japan, currently tentatively designated as Tulip breaking virus-li (TBV-li), was determined. The sequence started within a single open reading frame (ORF) that encoded the carboxyl terminus of the large nuclear inclusion protein (NIb) and the complete 275-amino-acid coat protein (CP), followed by a 3-untranslated region (3-UTR) of 204 nts. The CP of TBV-li shared 91% amino acid (aa) sequence identity with that of TBV lily strain Dutch isolate (TBV-lily). The nt sequences of their 3-UTR were 94% identical. However both viruses shared only 60–65% sequence identities with TBV tulip strain Niigata isolate in the corresponding regions. The results suggest that TBV-li is closely related to TBV-lily, and that these two TBV lily strains should be classified into a species different from TBV tulip strains. We therefore support a proposal to rename TBV-lily Lily mottle virus (LMoV), and suggest that TBV-li is another strain of LMoV (LMoV-J).