Comparison of proteins and nucleic acids of Echinochloa ragged stunt and rice ragged stunt viruses.

Echinochloa ragged stunt virus (ERSV) and rice ragged stunt virus (RRSV; Reoviridae) were purified from their respective host plants and disrupted in SDS. Evidence for the double-strandedness of ERSV RNA was obtained. Electrophoresis in 10% polyacrylamide gels resolved the RNAs of each virus into 10 segments, ranging for ERSV from 0.61 x 10(6) to 2.8 x 10(6) daltons, with a sum representing the total genome of 17.89 x 10(6) daltons, and for RRSV from 0.6 x 10(6) to 2.98 x 10(6) daltons, with a sum of 18.15 x 10(6) daltons. Although the overall RNA pattern of the two viruses was similar, there were distinctive features. Using 7.5-15% polyacrylamide gels, electrophoresis of SDS-dissociated RRSV particles yielded five major proteins of 129 x 10(3), 123 x 10(3), 63 x 10(3) and 35 x 10(3) daltons, and two minor proteins of 113 x 10(3) and 88 x 10(3) daltons, respectively, while comparable samples of ERSV yielded four major proteins of 127 x 10(3), 123 x 10(3), 63 x 10(3) and 34 x 10(3) daltons, and three minor proteins of 103 x 10(3), 50 x 10(3) and 49 x 10(3) daltons, respectively. We conclude from this and other evidence that ERSV and RRSV are closely related viruses and should be classified in the same subgroup, despite reported differences in the morphology of their outer capsids.

The microbial production of amylase inhibitor and its application. I. Isolation and cultivation of Streptomyces nigrifaciens NTU-3314.

In the course of screening amylase inhibitor producing, microorganisms, a strain identified as Streptomyces nigrifaciens NTU-3314 was found to have the highest inhibitor-producing ability among the other isolated strains. This strain was aerobically cultured at 30 degrees C in a 5l jar fermentor with a working volume of 2l. The optimum cultural medium consisted of defatted soybean flake 3.0%, potato starch 4.0%, casein 0.6%, sucrose 0.6%, serine 0.02% and NaCl 0.8% (pH 7.0). With an aeration rate of 1.5 vvm, an agitation speed of 300 rpm and an inoculum of 15% seed (previously grown in seed medium 3), the highest amount of inhibitor was obtained after 24 hours of cultivation. The amylase inhibitor produced had inhibitory effects on both alpha-amylase and glucoamylase, but not on beta-amylase, alpha-glucosidase, beta-glucosidase or dextranase. It was quite stable in 0.1M phosphate buffer (pH 7.0) and nearly 100% of its activity was retained even after boiling at 100 degrees C for 20 min.