Objective. Interleukin‐10 (IL‐10) has been shown to exert both antiinflammatory and immunostimulatory effects in vivo and in vitro. We therefore sought to examine the role of this cytokine in rheumatoid arthritis (RA) by assessing serum and synovial fluid IL‐10 levels. Methods. Serum and synovial fluid samples were collected from patients with RA and patients with various inflammatory, infectious, and noninflammatory arthritides (controls). IL‐10 was assayed using an IL‐10‐specific enzyme‐linked immunosorbent assay, and messenger RNA (mRNA) levels were assessed by semi‐quantitative polymerase chain reaction (PCR) techniques. Results.Both RA serum and synovial fluid contained significantly elevated IL‐10 levels compared with levels in normal subjects or in control patients (P < 0.01). Some patients with spondylarthropathy also manifested increased serum levels of IL‐10. Serum levels of IL‐10 did not correlate with standard measures of clinical activity, but were shown to correlate significantly with serum rheumatoid factor (RF) titers and in vitro levels of spontaneous IgM‐RF production (P < 0.05). PCR analyses demonstrated the constitutive expression of IL‐10 mRNA by the non–T cell population, and semiquantitative PCR analysis documented elevated levels of IL‐10 mRNA in circulating mononuclear cells of those RA patients who were not treated with slow‐acting antirheumatic drugs. Analysis of IL‐10 mRNA revealed the cytokine to be of human, and not viral, origin. Conclusion. These data suggest that there is increased production of IL‐10 by non‐T cells in patients with RA. This may contribute to the diminished T cell function and increased antibody and RF production in these patients.

Rice (Oryza sativa L.) can produce black grains as well as white. In black rice, the pericarp of the grain accumulates anthocyanin, which has antioxidant activity and is beneficial to human health. We developed a black rice introgression line in the genetic background of Oryza sativa L. ‘Koshihikari’, which is a leading variety in Japan. We used Oryza sativa L. ‘Hong Xie Nuo’ as the donor parent and backcrossed with ‘Koshihikari’ four times, resulting in a near isogenic line (NIL) for black grains. A whole genome survey of the introgression line using DNA markers suggested that three regions, on chromosomes 1, 3 and 4 are associated with black pigmentation. The locus on chromosome 3 has not been identified previously. A mapping analysis with 546 F2 plants derived from a cross between the black rice NIL and ‘Koshihikari’ was evaluated. The results indicated that all three loci are essential for black pigmentation. We named these loci Kala1, Kala3 and Kala4. The black rice NIL was evaluated for eating quality and general agronomic traits. The eating quality was greatly superior to that of ‘Okunomurasaki’, an existing black rice variety. The isogenicity of the black rice NIL to ‘Koshihikari’ was very high.

A plasmid (pRSE562) containing the metE and metR genes of Escherichia coli was used to study the expression of these genes and the role of the MetR protein in regulating metE expression. DNA sequence analysis of the 236-base-pair region separating these genes showed the presence of seven putative met boxes. When this plasmid was used to transform either wild-type E. coli, metE mutant, or metR mutant, MetE enzyme activity increased 5-to 7-fold over wild-type levels. The metR gene was subcloned from pRSE562, and this plasmid, pMRIII, relieved the methionine auxotrophy of a metR mutant after transformation. The metR gene was also cloned into a vector containing the APL promoter, and the MetR protein was overexpressed and purified to near homogeneity. This protein, when added to an in vitro DNAdependent protein synthesis system in which the MetE and/or MetR proteins were synthesized, caused a large increase in the expression of the metE gene but a decrease in the expression of the metR gene. The in vitro expression of both genes was inhibited by the MetJ protein and S-adenosylmethionine in the presence or absence of MetR protein. These results provide evidence that the product of the metR gene is a trans-activator of the expression of the metE gene and that the expression of the metR gene is under autogenous regulation and is repressed by the MetJ protein.

Two laboratory-scale biological filters were operated to investigate the effects of alkalinity and pH on removal of nitrate and nitrite in sulfur denitrification filter processes. The concentration of sodium bicarbonate in the feed media was changed from 120 to 240 mg/l during about 3 months in a filter (Run A). The other filter was initially fed with 300 mg/l and then with 240 mg/l (Run B). The performance of the filter was monitored by measuring pH, nitrate, nitrite, sulfate, alkalinity, and thiosulfate. Nitrate concentration in effluent rapidly decreased to lower levels within several days for both filters after inoculation of enrichment culture of sulfur denitrifiers. However there was a large difference in removal of nitrite. When rapid removal of nitrate took place, nitrite accumulation was observed and remained while the bicarbonate concentration was 120 and 150 mg/l. On the other hand the nitrite accumulation disappeared when more bicarbonate (240 and 300 mg/l) was supplied. The experimental results indicated that the nitrite accumulation was closely related to pH condition and alkalinity level in the filter. The stable data of effluent water quality for 5 cases were collected and the relationship discussed between nitrite concentration and pH in effluents. The relationship indicated a strong pH dependency on nitrite accumulation below pH of 7.4. The pH condition around 7 is not so inhibitory to biological activity. Therefore, the pH within the biofilm would be low enough to suppress the nitrite reduction by sulfur denitrifiers, while the pH in effluent was not in the inhibitory range. It was recommended to keep the pH higher than 7.4 to prevent nitrite accumulation in the sulfur denitrification filter.

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