Growth of recombinant equine herpesvirus 1 (EHV-1) replaced with passage-induced mutant gene 1 and gene 71 derived from an attenuated EHV-1 in cell cultures and in the lungs of mice

The relationship of passage-induced mutant genes 1 and 71 of an attenuated equine herpesvirus 1 (EHV-1) with virulence was analysed by constructing nine recombinant EHV-1 viruses by homologous recombination. Gene 1 or/and gene 71 of a virulent EHV-1 strain, HH1, was replaced by a mutant gene 1 or/and 71 of an attenuated HH1 strain, BK343, respectively. The beta-galactosidase gene of Escherichia coli was inserted within the gene 1 or 71 coding sequence of HH1 to inactivate the genes. Virus replications of these recombinant viruses in cell cultures were similar, but release of the gene 71-inactivated virus from infected cells was delayed compared to that of the other viruses. Plaque sizes of the recombinant viruses were similar to those of HH1, but those of BK343 were significantly smaller, indicating an effect of some unknown factor(s) on viral cell-to-cell spread. The growth abilities of the recombinant viruses with a mutant gene 1 or/and 71 in lungs of mice were similar to those of HH1, but those of gene 71-inactivated viruses were reduced to the level of BK343 and the titers were about 100-times lower than those of the other recombinant viruses. These results indicate that the mutant genes 1 and 71 of BK343 might not confer an attenuated nature to EHV-1.     

The respiratory burst activity of bottlenose dolphin neutrophils elicited by several stimulants

To investigate the early host defense function in aquatic animals, the respiratory burst activity of bottlenose dolphin neutrophils against soluble and particulate stimulants was measured by luminol-dependent chemiluminescence assays and compared with those of bovine and human. Dolphin neutrophils generated the respiratory burst in response to phorbol 12-myristate 13-acetate (PMA), concanavalinA (ConA), heated-plasma (HP), and homologous-plasma opsonized zymosan except N-formyl-Met-Leu-Phe (fMLP). However, the respiratory burst of dolphin neutrophils stimulated by lipopolysaccharide and Staphylococcus aureus was inferior to those of bovine and human. Furthermore, DP-OZ also induced the respiratory burst of bovine and human neutrophils. In conclusion, dolphin neutrophils responded to several soluble and particulate stimulants as well as human neutrophils, but were refractory or slightly responded to bacterial agents.     

Depressed gross mineralization and immobilization of nitrogen and changes in microbial population in soil after heat treatment

Partial sterilization causes a change in N mineralization in soil. An increase in the net rate of N mineralization was reported in soil with chloropicrin applied to it (Rovira 1976), and has been well known in soil fumigated with chloroform to measure the microbial biomass N (Jenkinson and Ladd 1981). The gross rate of N mineralization increased in soil inoculated with fresh soil following fumigation with chloroform (Shen et al. 1984). The increased rate of N mineralization has been attributed to the rapid decomposition of organisms killed by partial sterilization (Jenkinson 1966). On the other hand, Nira et al. (1996) reported that the application of a fumigant in a field depressed the gross rates of N mineralization and immobilization in spite of the increase in the net rate of N mineralization. These results suggested that the increase in the net rate of N mineralization by partial sterilization is presumably due to the change in the ratio of N mineralization to immobilization. However, the residues of a fumigant may depress gross N transformation in the field, because the residues may continue to influence microbial activity long after the original treatment (Jenkinson 1966). Some effects of partial sterilization without residues on gross N mineralization remain to be determined.     

Conversion of soil particle size distribution and texture classification from ISSS system to FAO/USDA system in Japanese paddy soils

ABSTRACT

The conversion between the two different systems, ISSS and FAO/USDA, of particle size distribution and soil texture classification is useful to characterize soil physical properties and usage of each published. The objective of this study is to test some functions that have been published for conversion from ISSS to FAO/USDA system for Japanese paddy soils and to select the best method. We tested the topsoils of 267 Japanese paddy fields using the log-linear method, log-normal method, multiple regression method, Skaggs et al.’s method, and Minasny and McBratney’s method. The least AIC was obtained using multiple regression method, and the equation derived was given as follows:

si_FAO/USDA = 1.305si_ISSS + 0.396fs_ISSS?0.100cs_ISSS ? 12.323

where si, fs, and cs are the percentage of silt, fine sand, and coarse sand respectively; ISSS and FAO/USDA is the fractionation system; and its RMSE was 3.1%. For the case that only the total sand content (s) is available instead of fine sand and coarse sand, the following equation was obtained:

si_FAO/USDA = 0.314si_ISSS + 1.533s_ISSS ? 20.903 (RMSE = 3.7%)

Among the non-empirical methods, the best estimation method was Skaggs et al.’s method, and its RMSE was 3.3%. The soil texture classification by FAO/USDA system using estimated particle size fractions by the above equation can be classified to correct categories. The accuracy ratio of the classification was 93-97%.     

Nitrogen accumulation in soybean [Glycine max (L.) Merr.] is increased by manure compost application in drained paddy fields as a result of increased soil nitrogen mineralization

The application of manure compost is an effective way to increase soybean [Glycine max (L.) Merr.] yield and nitrogen (N) fertility in drained paddy fields. We investigated changes in soil N mineralization during soybean cultivation using reaction kinetics analysis to determine the contribution of increased N mineralization after manure compost application (at a rate of 0 to 6?kg?m^?2) on N accumulation and seed yield of soybean under drained paddy field conditions. The seed yield and N accumulation decreased markedly in the second and third year of the experiment, but soil N mineralization increased in both years. No decrease in soil N mineralization occurred even after two soybean crops. Soil N availability was not the main cause of decreased soybean yield in the second and third years. The differences in plant aboveground N content between plots with and without manure compost was similar to the increase in N mineralization caused by manure compost application in the second and third years. The application of 6?kg?m^?2 of manure compost increased the amount of ureide-N and nitrate-N in soybean in the third year. Our results suggest that manure compost application increases soil N mineralization and soybean N₂ fixation, resulting in increased N accumulation and seed yield. However, the soybean yield remained less than 300?g?m^?2 in the second and third years (i.e., below the yield in the first year) at all levels of manure compost application due to the remarkable decrease of N accumulation in the second and the third crops.     

Types of frass produced by the ambrosia beetle <Emphasis Type="Italic">Platypus quercivorus</Emphasis> during gallery construction,and host suitability of five tree species for the beetle

We studied the biology of the ambrosia beetle Platypus quercivorus in the logs of five tree species to determine: (1) the relationship between the amount of frass produced by beetles and tunnel length, (2) the relationship between frass shape and the morphological characteristics of P. quercivorus mouthparts, and (3) the suitability of five tree species for P. quercivorus reproduction. Five logs each from healthy Quercus crispula, Q. serrata, Castanea crenata, Sorbus japonica, and Cryptomeria japonica trees were used in this experiment. The results showed that there was a linear relationship between the amount of frass and tunnel length. Whenever powdery frass was produced, larvae were found in the gallery in the log, while fibrous frass was present only in galleries that contained just adults. The mouthparts of adults were completely sclerotized, which likely accounts for the fibrous frass production. Host preference of P. quercivorus was examined at two stages using five tree species. The first stage is digging initiation, which concerns male preference for digging a tunnel. More holes were made by males on S. japonica and Q. serrata logs, while fewer holes were made on C. japonica logs. The second stage is characterized by female orientation, mating, and progeny development. Platypus quercivorus could complete its lifecycle only in the two Quercus spp.