SUMMARYChlorophyll degradation is an important phenomenon in the senescence process. It is necessary for the degradation of certain chlorophyll-protein complexes and thylakoid membranes during leaf senescence. Mutants retaining greenness during leaf senescence are known as 'stay-green' mutants. Non-functional type stay-green mutants, which possess defects in chlorophyll degradation, retain greenness but not leaf functionality during senescence. Here, we report a new stay-green mutant in rice, nyc3. nyc3 retained a higher chlorophyll a and chlorophyll b content than the wild-type but showed a decrease in other senescence parameters during dark incubation, suggesting that it is a non-functional stay-green mutant. In addition, a small amount of pheophytin a, a chlorophyll a-derivative without Mg 2+ ions in its tetrapyrrole ring, accumulated in the senescent leaves of nyc3. nyc3 shows a similar but weaker phenotype to stay green (sgr), another non-functional stay-green mutant in rice. The chlorophyll content of nyc3 sgr double mutants at the late stage of leaf senescence was also similar to that of sgr. Linkage analysis revealed that NYC3 is located near the centromere region of chromosome 6. Map-based cloning of genes near the centromere is very difficult because of the low recombination rate; however, we overcame this problem by using ionizing radiationinduced mutant alleles harboring deletions of hundreds of kilobases. Thus, it was revealed that NYC3 encodes a plastid-localizing a/b hydrolase-fold family protein with an esterase/lipase motif. The possible function of NYC3 in the regulation of chlorophyll degradation is discussed.

Yellowing/chlorophyll breakdown is a prominent phenomenon in leaf senescence, and is associated with the degradation of chlorophyll - protein complexes. From a rice mutant population generated by ionizing radiation, we isolated nyc4-1, a stay-green mutant with a defect in chlorophyll breakdown during leaf senescence. Using gene mapping, nyc4-1 was found to be linked to two chromosomal regions. We extracted Os07g0558500 as a candidate for NYC4 via gene expression microarray analysis, and concluded from further evidence that disruption of the gene by a translocation-related event causes the nyc4 phenotype. Os07g0558500 is thought to be the ortholog of THF1 in Arabidopsis thaliana. The thf1 mutant leaves show variegation in a light intensity-dependent manner. Surprisingly, the Fv /Fm value remained high in nyc4-1 during the dark incubation, suggesting that photosystem II retained its function. Western blot analysis revealed that, in nyc4-1, the PSII core subunits D1 and D2 were significantly retained during leaf senescence in comparison with wild-type and other non-functional stay-green mutants, including sgr-2, a mutant of the key regulator of chlorophyll degradation SGR. The role of NYC4 in degradation of chlorophyll and chlorophyll - protein complexes during leaf senescence is discussed.

These results suggest that intranasal sensitization with SEA in the absence of adjuvants induces a Th2 immune reaction, reflecting the hallmarks of the initiation of allergic rhinitis both in vivo and in vitro, which is genetically regulated.

of the submandibular gland: a case report and literature review. J Oral Pathol Med 1998; 27: 225-8. C Munksgaard, 1998. Oncocytes are characterized by a remarkable number of mitochondria as demonstrated by electron microscopy. Oncocytomas are very rare tumors that are usually benign and typically occur in the parotid gland. Oncocytic carcinomas are ex-Key words: mitochondria; oncocyte; oncocytic ceedingly rare in the salivary glands. We describe a 69-year-old Japanese man carcinoma; oncocytoma; submandibular gland with an oncocytic carcinoma of the submandibular gland. We reviewed 38 articles describing oncocytic carcinoma of the head and neck that included Michihiro Nakada, Department of Otorhinolaryngology, Okayama University clinicopathologic features. Oncocytic carcinomas appear to arise from benign Medical School, Shikata-Cho 2-5-1, oncocytomas, or may also arise de novo. In oncocytic carcinoma of the head Okayama-shi 700-8558, Japan and neck, the presence of distant, rather than local lymph node, metastasis is the most important prognostic indicator.

ABSTRACT. The internal transcribed spacer (ITS) and external transcribed spacer (ETS) regions of nuclear ribosomal DNA (nrDNA) in 30 species and four varieties of Chrysanthemum and 54 species and one variety in the closely related genera within the tribe Anthemideae, the family Asteraceae are sequenced and analyzed to clarify and justify their molecular characteristics and close relationships. Chrysanthemum forms a polytomy clade with Ajania. In addition, the substitution rates of the ITS and ETS regions of Chrysanthemum and Ajania are quite low as compared with the closely related genera. Chrysanthemum and Ajania are too close to separate from each other and have been currently, taxonomically treated as Chrysanthemum in combination. The species of Chrysanthemum studies are highly adapted and diversified with low level DNA divergence and thus, they might have reticulation and/or introgression event during evolutional process. According to the intergeneric mean of Chrysanthemum, a part of the radiate genera and species such as Ajania members studied, Elachanthemum intricatum and Phaeostigma variifolium are placed in the Chrysanthemum clade. However, C. sinuatum is excluded from this clade. The species of Chrysanthemum studied showed so close, relationships with cryptic differences in ITS and ETS with each other and thus, they could be distinctly separated from the other closely related genera in the tribe Anthemideae.