The complete nucleotide sequence of the rice grassy stunt virus genome and genomic comparisons with viruses of the genus Tenuivirus.

Rice grassy stunt virus (RGSV, IRRI isolate) has six genomic RNA segments. The nucleotide (nt) sequences of RNAs 1-4 were determined. The cumulative length of the RGSV genome, including RNAs 5 and 6, was 25142 nt. All six RNA segments had an ambisense coding strategy and almost identical terminal sequences over 17 nt. The virus complementary (vc) sequence of the largest segment, RNA1, had an open reading frame encoding a protein of Mr 339133 (the 339.1K protein), while the virus sense (v) sequence encoded a protein of Mr 18910 in the 5'-proximal region. The predicted 339.1K protein contained the highly conserved motifs of the RNA-dependent RNA polymerase and a short but distinct Arg/Gly-rich stretch at the C terminus. The putative RNA polymerase showed strong similarity with that of rice stripe tenuivirus (RSV); they shared 37.9% amino acid identity over 2140 residues. The predicted proteins of Mr 23280 on vRNA2 and 93 879 on vcRNA2 were only slightly similar in sequence to the proteins encoded by vRNA2 and vcRNA2 of other tenuiviruses. The predicted proteins encoded by RNA3 and RNA4 did not show significant similarity to any database proteins. Only the putative RNA polymerase encoded on RNA1 was well-conserved between RGSV and RSV. The low sequence similarities in proteins encoded by RNAs 2, 5 and 6, together with the unique RNA segments 3 and 4, indicate that RGSV may be distinct from other tenuiviruses.

Quantitative Analysis of Trace Moisture in N(2) and NH(3) Gases with Dual-Cell Near-Infrared Diode Laser Absorption Spectroscopy.

This paper demonstrates our optical measurement system based on near-infrared tunable diode laser absorption spectrometry and reports the results of trace moisture determination in nitrogen and ammonia gases. A near-infrared InGaAsP distributed feedback diode laser operating at room temperature was employed as the optical source. We used a dual-cell detection strategy to cancel common mode noise from the diode laser and remove the effect of the residual moisture absorption in the beam path outside the sample cell. We also used this method to successfully eliminate the interfering absorption of matrix gas molecules such as NH(3). The detection limit of H(2)O absorption of 4 ppb in nitrogen and 12 ppb in ammonia was obtained using a single-pass absorption cell of only 92 cm in length and the average results of 10 scan measurements. This system has characteristics of both the high sensitivity and capability of in situ and real-time measurement.

The proteins encoded by rice grassy stunt virus RNA5 and RNA6 are only distantly related to the corresponding proteins of other members of the genus Tenuivirus.

The genome of rice grassy stunt virus (RGSV) consists of six RNA segments. The nucleotide (nt) sequences of the two smallest segments, RNAs 5 and 6, were determined and found to comprise 2704 and 2584 nt, respectively. The 5'- and 3'-terminal sequences of both RNAs were identical over a length of 21 nt and could potentially form a panhandle-like structure due to intramolecular complementarity. Each RNA segment contained a virus (v) sense open reading frame (ORF) in the 5'-proximate region, and a virus complementary (vc) ORF in the 3'-proximate region, indicating an ambisense coding strategy. The protein encoded by the ORF on the vc strand of RNA5 was identified as the viral nucleocapsid protein (M(r) 35927). The ORF on the v strand of RNA6 encoded a protein of M(r) 20581 which represented the major nonstructural protein, previously shown to be produced in RGSV-infected rice tissues. The predicted proteins encoded by RGSV RNAs 5 and 6 were only distantly similar in sequence to the four proteins encoded by RNAs 3 and 4 of other viruses belonging to the genus Tenuivirus. These low sequence similarities, together with the apparently distinct number of genome segments, set RGSV apart from the other tenuiviruses and indicate that it should be placed in a taxonomically separate genus.