Natural hybridization between Rhododendron delavayi and R. cyanocarpum (Ericaceae), from morphological, molecular and reproductive evidence.

The natural hybridization that occurs between two sympatric species of Rhododendron subgenus Hymenanthes in Yunnan, China, was investigated. In field observations, it was noted that the putative hybrids between R. delavayi Franch. and R. cyanocarpum (Franch.) Franch. ex W.W. Sm. had intermediate morphologies. On the basis of morphology, chloroplast DNA (trnL-rpl32) and nuclear DNA (waxy), hybrids and parental species were identified. Hybridization occurred in both directions, but was asymmetrical, with R. delavayi as the major maternal parent. Reciprocal hand pollination treatments showed that either species, as pollen donor or pollen receiver, could produce fruits. It was noted that fruit set varied among treatments. The same pollinators (bumblebees) were shared in both parental species. From these results, we conclude that individuals with intermediate morphologies are indeed of hybrid origin from natural hybridization between R. cyanocarpum and R. delavayi. Furthermore, we presume the hybridization at the study site could have been initiated by habitat disturbance in the 1950s, and we may hence witness the early stages of hybrid swarm formation.

Natural hybridization origin of Rhododendron agastum (Ericaceae) in Yunnan, China: inferred from morphological and molecular evidence.

The natural hybridization that occurs between two sympatric species of Rhododendron subgenus Hymenanthes in Yunnan, China, was investigated. The assumed parents, Rhododendron delavayi Franch. and R. decorum Franch., are morphologically distinct, and the putative hybrid species, R. agastum Balf. f. et W. W. Smith, has an intermediate morphology. We used the main morphological characters, sequences of the nuclear ribosomal DNA ITS region, and the chloroplast DNA trnL-F intronspacer to analyze the three species, and compared these morphological and molecular data with an artificial hybrid between R. decorum (female symbol) x R. delavayi (male symbol). From the results, we conclude that R. agastum is a natural hybrid between a female R. delavayi and a male R. decorum.

[Correlations of CpG island methylator phenotype and OPCML gene methylation to carcinogenesis of hepatocellular carcinoma].

BACKGROUND & OBJECTIVE: CpG island methylator phenotype (CIMP) is cancer-specific and involves in the promoter hypermethylation of multiple genes. It is correlated to the genesis or prognosis of various tumors, but it has rarely been reported in hepatocellular carcinoma (HCC). OPCML (opioid-binding protein/cell adhesion molecule-like) gene has been studied mainly in epithelial ovarian cancer, and is thought to be a candidate tumor suppressor gene in epithelial ovarian cancer. This study was to explore the correlations of CIMP and OPCML gene expression to the carcinogenesis of HCC. METHODS: The methylation status of OPCML, p15, SOCS-1, GST-p, RAR-b, p16, p73, p14, MGMT, hMLH1 in 50 specimens of HCC and pericancer tissues was detected using methylation-specific polymerase chain reaction (MSP). RESULTS: The hypermethylation rates of genes were higher in HCC than in pericancer tissues [OPCML (70.0% vs. 64.6%), p15 (58.0% vs. 50.0%), SOCS-1 (78.0% vs. 50.0%), GST-p (56.0% vs. 27.1%), RAR-b (30.0% vs. 6.3%), p16 (26.0% vs. 14.6%), p73 (16.0% vs. 0%), p14 (36.0 vs. 27.1%), MGMT (16.0% vs. 10.4%), and hMLH1 (18.0% vs. 4.2%)]. The methylation rates of SOCS-1, GST-p, RAR-b, p16 and p73 were significantly higher in HCC than in adjacent non-neoplastic tissues (P<0.05). The recurrence occurred earlier in CIMP-positive group (> or =3 methylated genes) than in CIMP-negative group (<3 methylated genes)(P<0.05). The 1-year disease-freely survival rate was significantly lower in CIMP-positive group than in CIMP-negative group (18.2% vs. 75.0%, P<0.05). CONCLUSIONS: CIMP exists in HCC, and may be a prognostic factor of HCC. Promoter methylation of OPCML gene may play an important role in hepatocarcinogenesis.