<Emphasis Type="Italic">LKF</Emphasis>, the locus regulating large grains in the rice cultivar ‘Fusayoshi’, is identical to the loci encoding a serine/threonine protein phosphatase with Kelch motif

The LKF locus, which regulates grain size in the rice cultivar ‘Fusayoshi’ showing large grain, has been mapped to the proximal part of the long arm of chromosome 3. An incomplete dominant allele, Lkf, caused large grain size of Fusayoshi. The structure and function of this locus, however, have not yet been determined. In a similar position to LKF on chromosome 3, two loci, Os03g0407400 (GS3) and LOC_Os03g44500, have been already reported as loci also regulating rice grain size. The objective of the present study was to determine the nucleotide sequences of both Os03g0407400 and LOC_Os03g44500 for different alleles at the LKF locus. Results showed that only one known single nucleotide polymorphism (SNP) in exon 10 of LOC_Os03g44500 was detected between a large-grain allele (Lkf) and a small-grain allele at the LKF locus, whereas no polymorphisms in Os03g0407400. This SNP, visualized using a dCAPS marker, clearly demonstrated nearly complete co-segregation with grain length in an F₂ population segregating the Lkf at LKF. Other large-grain mutant lines with large-grain alleles at the LKF locus, which originated from another cultivar ‘Gimbozu’, also showed the same SNP in exon 10 of LOC_Os03g44500. It was concluded from these results that LKF is identical to LOC_Os03g44500, and the detected SNP in exon 10, at least, which is included in Kelch-like repeat motif, could be essential for expression of the large-grain phenotype.     

Stimulation of Adrenal Chromaffin Cell Proliferation by Hypercalcemia Induced by Intravenous Infusion of Calcium Gluconate in Rats

Increased incidence of adrenal pheochromocytoma is frequently encountered in rat carcinogenicity studies. In some of the studies, the finding is judged to be due to a rat-specific mechanism of carcinogenesis caused by a disturbance of calcium homeostasis. However, direct evidence that the proliferation of chromaffin cells in the adrenal medulla is induced solely by hypercalcemia is not available. In this study, calcium gluconate was intravenously infused for 7 days to rat chromaffin cells by a tail cuff method, and cumulative labeling with bromodeoxyuridine (BrdU) was carried out to evaluate the proliferative activity. The serum calcium concentration was dose-dependently increased, and a high calcium concentration was stably sustained from day 2 to 7. In the adrenal medulla, BrdU-positive chromaffin cells increased in the calcium gluconate-treated animals, and the BrdU-labeling index increased in a dose-dependent manner. In addition, an increased BrdU-labeling index of chromaffin cells was shown to correlate with the serum calcium concentration. Our results demonstrate that hypercalcemia directly enhances the proliferative activity of chromaffin cells and that the proliferative activity is correlated with the serum calcium concentration.     

Role of nitric oxide in hemodialysis-related hypotension in an experimental renal dysfunction dog model

To clarify the role of nitric oxide (NO) in hemodialysis (HD)-related hypotension, the relationship between plasma NO metabolites (NOx) and blood pressure changes, and the effect of N(G)-monomethyl-L-arginine (L-NMMA), a NO synthase inhibitor, on changes in blood pressure were evaluated in an experimental renal dysfunctional dog model. In order to create a renal dysfunction model, gentamicin was administered to male beagles in which 7 of 8 renal artery branches had been ligated. Normal renal functional and dysfunctional dogs underwent 3 hr of HD per day for 3 days. HD induced a transient decrease in mean blood pressure in the normal renal functional dogs. In renal dysfunctional dogs, a continuous hypotension occurred with a gradual increase in the plasma NOx concentration during HD. Although L-NMMA prevented the fall in blood pressure, it did not significantly change the plasma NOx concentration during HD. These results suggest that NO contributes to HD-related hypotension in renal dysfunctional dogs but the plasma NOx concentration does not reflect the change in blood pressure.     

Endoscopic findings on alimentary lymphoma in 7 dogs

Alimentary lymphoma was evaluated endoscopically in 7 dogs and a histopathological examination was made to detect the origin of neoplastic lymphocytes in 5 dogs. A solitary mass in the rectum (1 case), irregular cobblestone appearance in the duodenum (4 cases) and a moderate irregular appearance resembling lymphocytic-plasmacytic enteritis (2 cases) were endoscopically detected. Endoscopic ultrasonography demonstrated increased thickness of the duodenal wall in 2 cases examined. Neoplastic lymphocytes of alimentary lymphoma proved to originate in T cells in all 5 cases examined by immunohistochemical analysis.     

Effects of the neutrophil elastase inhibitor (ONO-6818) on acetic acid induced colitis in Syrian hamsters

Neutrophil elastase (NE) released from neutrophils during inflammation is related to tissue disturbance and organ failure. We investigated the effects of an orally active NE inhibitor, ONO-6818, on acetic acid induced colitis in Syrian hamsters. The ulcer area, hemoglobin level in the colonic lumen, NE activity, and tissue myeloperoxidase (MPO) activity in the colitis control animals were significantly increased compared to the normal control ones. Either oral or subcutaneous treatment with ONO-6818 had significant inhibitory effects on the ulcer area, hemoglobin level and NE activity in the colonic lumen, but ONO-6818 did not have a significant inhibitory effect on tissue MPO activity. We conclude that NE is closely related to the development of inflammation in acetic acid-induced colitis in Syrian hamsters and that the condition is improved by the inhibition of NE.     

Phenotypic analysis of hepatic lymphocytes from healthy dogs

Phenotypes of lymphocytes from laparoscopically biopsied liver tissues of eleven healthy beagle dogs were analyzed. The proportion of CD3(+) lymphocytes (T cells), CD3 (-)CD21(+) lymphocytes (B cells) and CD3 (-)CD21(-) lymphocytes (non-T non-B lymphocytes), and the CD4(+)/CD8(+) ratio in the canine hepatic lymphocytes were 54.8 +/- 11.9%, 4.7 +/- 3.1%, 40.7 +/- 13.2%, and 0.33 +/- 0.12, respectively, while those in peripheral blood lymphocytes were 85.4 +/- 6.5%, 9.3 +/- 6.1%, 5.3 +/- 1.8%, and 1.64 +/- 0.36, respectively. These results indicated that the constitution of hepatic lymphocytes quite differed from that of peripheral blood lymphocytes in dogs, and suggested that the regional immunity in canine liver might be specific.     

Effect of ethanol on nitrate and nitrite reduction and methanogenesis in the ruminal microbiota

The effect of ethanol on nitrate and nitrite reduction was examined by conducting in vitro experiments with mixed ruminal microbes. The addition of ethanol to cultures of mixed ruminal microbes stimulated nitrate reduction, and, to a greater extent, nitrite reduction, which resulted in a decrease in nitrite accumulation. However, known nitrate‐reducing ruminal bacteria, such as Selenomonas ruminantium, Veillonella parvula and Wolinella succinogenes, were unable to utilize ethanol directly as an electron donor for nitrate reduction. No nitrate‐reducing bacterium capable of utilizing ethanol was found in the rumen of goats. However, when mixed ethanol‐utilizing, hydrogen gas (H₂)‐producing bacteria (Ruminococcus albus and Ruminococcus flavefaciens) were added to the culture of the mixed nitrate‐reducing bacteria described above, nitrate and nitrite reduction was observed. These results suggest that the nitrate‐reducing bacteria utilized the H₂ that was produced from ethanol oxidation by the ethanol‐utilizing bacteria as an electron donor. It is conceivable that the stimulation of nitrate and nitrite reduction by ethanol, observed in the culture of mixed ruminal microbes, was a result of electron transfer from ethanol to nitrate, and nitrite through H₂, that is, ‘interspecies hydrogen transfer’ from ethanol‐metabolizing bacteria to nitrate‐reducing bacteria. Thus, the addition of ethanol to high‐nitrate diets may be effective for preventing nitrate poisoning. Furthermore, methane production was reduced to less than one‐third by the addition of mixed nitrate‐reducing bacteria to the co‐culture of mixed methanogens with mixed ethanol‐utilizing bacteria incubated in a medium containing ethanol and nitrate. Therefore, the addition of ethanol and nitrate may decrease methanogenesis without suppressing overall fermentation in the rumen.     

Intraocular peripheral nerve sheath tumor in a dog

A tumor within the right globe in a 9-year-old Shetland sheepdog was examined pathologically. The tumor was composed of spindle or oval cells arranged in interwoven bundles with intervening collagenous or mucinous matrices. Immunohistochemically, the tumor bound antibody directed to S-100 protein and vimentin, but not to desmin, actin smooth muscle, or neurofilament. Electron microscopy revealed that the tumor cells had poorly developed cytoplasmic processes, desmosomes between closely contiguous cells, and a discontinuous basement membrane-like material. Based on these findings, the tumor was diagnosed as a peripheral nerve sheath tumor (PNST) histologically. To the authors' knowledge, this is the first reported case of intraocular PNST in dogs.     

Rhizopus Rot of Mulberry-grafted Saplings Caused by Rhizopus oryzae

A new disease on stocks of mulberry-grafted saplings was found in Tsukuba in 1999. A representative isolate of the Rhizopus species that was consistently isolated from rotted tissues was pathogenic to healthy mulberry stocks. The causal fungus was identified morphologically as Rhizopus oryzae Went & Prinsen Geerligs. Rhizopus rot (“Naefuhaibyou” in Japanese) was proposed for the name of the disease. This is the first report on a mulberry disease caused by R. oryzae. Received 30 March 2001/ Accepted in revised form 4 June2001