亚洲栽培稻两大亚种之间同工酶基因型的主要区别

选择亚洲重要稻作区的中国、日本、朝鲜、印度、泰国、缅甸、尼泊尔等地的栽培稻品种89份及野生稻与栽培稻的中间稻系14份为材料,根据形态进行分类并检测其同工酶。从结果看,Amp-2、Acp-1和Cat-1三个同工酶对于籼粳分类有重要的作用。     

The extinction of genetic resources of Asian wild rice, Oryza rufipogon Griff.: A case study in Thailand

Natural populations of wild rice, Oryza rufipogon Griff., are now threatened with the disturbance of their natural habitats by various human activities. To obtain basic information on genetic erosion or loss of genetic diversity in wild rice, we investigated how environmental changes of habitat affected the genetic structure of its natural population at a study site in the central plain of Thailand. During 10 years from 1985 to 1994, the wild-rice population at this site was seriously destroyed and fragmented. Using two sets of seed sample collected in 1985 and 1994 from the same population, allozyme variability at 17 loci of 11 enzymes were examined. Isozyme genotypes of mother plants of seed samples were estimated by the segregation in each progeny, and we calculated genetic parameters for the population. Gene diversity severely decreased in the 1994 sample compared with the 1985 sample. It is supposed that declining and fragmentation of the wild rice population, which happened during the 10 years, caused loss of genetic variability and forced the habitually outbreeding plants to inbreed, accelerating a reduction in gene variability. Pgi1-1 allele which was common in Indica rice cultivars of this region was found in the wild rice plants growing at the side of rice fields. Probably, introgression has occurred between wild and cultivated rice plants, and consequently the intrinsic nature of wild rice was gradually blurred by cultivar genes. We must realize that the genetic erosion of wild rice is rapidly proceeding and that an action for their conservation in natural environment, so called in situ conservation, is urgently needed.     

Characterization of gelatinolytic enzymes in the skeletal muscle of red sea bream Pagrus major

Gelatinolytic enzymes were partially purified from the skeletal muscle of red sea bream Pagrus major and characterized to obtain information on post mortem tenderization of fish muscle. Four gelatinolytic activities, G1 (90 kDa), G2 (65 kDa), G3 (60 kDa), and G4 (100 kDa), were detected in the Q Sepharose column. G1, the major gelatinolytic enzyme, and G4 were identified as serine proteinases from results of inhibitor spectrum and substrate specificity. By contrast, G2 and G3 were found to be metalloproteinases since these were inhibited by ethylenediamine tetraacetic acid and o-phenanthroline, and activated by 4-aminophenylmercuric acetate. The optimum pH and temperature of these enzymes were in the ranges of 7–9 and 20–40°C, respectively.     

Measurement of ammonia volatilization loss using a dynamic chamber technique: A case study of surface-incorporated manure and ammonium sulfate in an upland field of light-colored Andosol

The present study aimed to elucidate ammonia (NH₃) volatilization loss following surface incorporation (0–15 cm mixing depth) of nitrogen (N) fertilizer in an upland field of light-colored Andosol in central Japan. A dynamic chamber technique was used to measure the NH₃ effluxes. Poultry manure, pelleted poultry manure, cattle manure, pelleted cattle manure and ammonium sulfate were used as N fertilizers for basal fertilization to a bare soil with surface incorporation. All three experiments in summer and autumn 2007 and in summer 2008 showed negligible NH₃ volatilization losses following the application of all N fertilizers with the same application rate of 120 kg N ha⁻¹ as total N; these negligible losses were primarily ascribed to chemical properties of the soil, that is, its high cation exchange capacity (283 mmol_c kg⁻¹ dry soil) and relatively low pH(H₂O) (5.9). In addition, the surface incorporation, the very small ratio of ammoniacal N to total N for the manure, and the decrease in soil pH to ≤5.5 following applications of ammonium sulfate were also advantageous to the inhibition of NH₃ volatilization loss from the field-applied N fertilizers.     

Isolation and enzymatic digestion of body complex of soybean seed

The body complex of the soybean seed (BCSS) was isolated from the single cells (27.2%) by a sequential procedure of autoclaving with water, cellulase digestion for the primary cell wall, pectinase digestion for the secondary cell wall, and defatting with hexane washing. Its characteristics were then investigated. The defatted BCSS (DBCSS) consisted of protein (76.5%) and mannose-rich carbohydrates (3.2%). Screening of the food-processing protease for the digestion of DBCSS was carried out, and a kind of alkaline protease was selected. The inner protein of DBCSS was easily extracted with 0.1 M sodium carbonate buffer, pH 10, and the insoluble shell of the body complex (SDBCSS) was left. SDBCSS consisted of hydrophobic amino acid-rich protein. SDBCSS was easily digested by the selected alkaline protease. SDBCSS was dissolved by boiling with sodium dodecyl sulfate-mercaptoethanol, and it was found to consist of a protein of approximately 3 kDa. The high enzymatic digestion including the selected protease for soybean seed and defatted soybean meal was carried out; both were extracted and digested with a yield of >99.5%. The final indigestible residue was found as paired hexagonal and filamentous organs of the soybean cells.     

Attachment and infection to MA104 cells of avian rotaviruses require the presence of sialic acid on the cell surface

To determine the characters of receptors on target cells for avian rotaviruses, the receptors on MA104 cells for the pigeon rotavirus PO-13, the turkey rotaviruses Ty-1 and Ty-3, and the chicken rotavirus Ch-1 were analyzed. Pretreatment of MA104 cells with neuraminidase greatly reduced the infection by all of the four avian rotavirus strains. Binding of the cell-attachment protein, purified VP8 expressed in bacteria, of strain PO-13 to MA104 cells was also inhibited by pretreatment of cells with neuraminidase. These findings suggest that avian rotaviruses primarily utilize sialic acid-containing molecules as receptors on MA 104 cells.     

Effect of tissue deterioration on postmortem BSE diagnosis by immunobiochemical detection of an abnormal isoform of prion protein

Surveillance for bovine spongiform encephalopathy (BSE) in fallen stock in Japan is conducted with a commercial enzyme-linked immunosorbent assay (ELISA) for mass screening, with Western blotting (WB) and immunohistochemistry performed for confirmation of the ELISA. All tests are based on immunological detection of an abnormal isoform of the prion protein (PrP(Sc)) in brain tissues, which have sometimes deteriorated by the time samples from fallen stock reach a diagnostic laboratory. To evaluate BSE surveillance procedures for fallen stock, we examined PrP(Sc) detection from artificially deteriorated BSE-affected bovine brain tissues with a commercial ELISA kit and compared the results with those of WB. The optical density (OD) values of the ELISA decreased with advancing deterioration of the tissues, whereas no reduction in the signal for PrP(Sc) was observed in WB, even when performed after 4 days of incubation at 37 degrees C. The progressive decrease in the OD values in the ELISA appear to be caused by a partial loss of the N-terminal moiety of PrP(Sc) due to digestion by endogeneous and/or contaminated microbial enzymes, and by the presence of ELISA inhibitors that are generated in deteriorated tissues. These results suggest that WB is the most reliable test for fallen stock, especially for cattle brains within decaying carcasses.     

Negative feedback regulation ensures the one receptor-one olfactory neuron rule in mouse

In the mouse olfactory system, each olfactory sensory neuron (OSN) expresses only one odorant receptor (OR) gene in a monoallelic and mutually exclusive manner. Such expression forms the genetic basis for OR-instructed axonal projection of OSNs to the olfactory bulb of the brain during development. Here, we identify an upstream cis-acting DNA region that activates the OR gene cluster in mouse and allows the expression of only one OR gene within the cluster. Deletion of the coding region of the expressed OR gene or a naturally occurring frame-shift mutation allows a second OR gene to be expressed. We propose that stochastic activation of only one OR gene within the cluster and negative feedback regulation by that OR gene product are necessary to ensure the one receptor-one neuron rule.