Yoshinobu Hayashi

Termites have colonized many habitats and are among the most abundant animals in tropical ecosystems, which they modify considerably through their actions. The timing of their rise in abundance and of the dispersal events that gave rise to modern termite lineages is not well understood. To shed light on termite origins and diversification, we sequenced the mitochondrial genome of 48 termite species and combined them with 18 previously sequenced termite mitochondrial genomes for phylogenetic and molecular clock analyses using multiple fossil calibrations. The 66 genomes represent most major clades of termites. Unlike previous phylogenetic studies based on fewer molecular data, our phylogenetic tree is fully resolved for the lower termites. The phylogenetic positions of Macrotermitinae and Apicotermitinae are also resolved as the basal groups in the higher termites, but in the crown termitid groups, including Termitinae + Syntermitinae + Nasutitermitinae + Cubitermitinae, the position of some nodes remains uncertain. Our molecular clock tree indicates that the lineages leading to termites and Cryptocercus roaches diverged 170 Ma (153-196 Ma 95% confidence interval [CI]), that modern Termitidae arose 54 Ma (46-66 Ma 95% CI), and that the crown termitid group arose 40 Ma (35-49 Ma 95% CI). This indicates that the distribution of basal termite clades was influenced by the final stages of the breakup of Pangaea. Our inference of ancestral geographic ranges shows that the Termitidae, which includes more than 75% of extant termite species, most likely originated in Africa or Asia, and acquired their pantropical distribution after a series of dispersal and subsequent diversification events.

The expression of mRNAs for vascular endothelial growth factor (VEGF) was examined in 42 cases of primary lung cancer tissues (18 adenocarcinomas, 18 squamous cell carcinomas, 2 large cell carcinomas, 3 small cell carcinomas, and 1 adenoid cystic carcinoma) and 4 human lung cancer cell lines. As seen by reverse transcription-PCR analysis, VEGF mRNAs were expressed predominantly as transcripts for the secretory forms of VEGF (VEGF121 and VEGF165), both in resected lung cancer tissues and in human lung cancer cell lines. The positive ratios of VEGF mRNA according to pathological type were 66.7% (12 of 18) in adenocarcinoma, 72.2% (13 of 18) in squamous cell carcinoma, 100% (2 of 2) in large cell carcinoma, and 67% (2 of 3) in small cell carcinoma. The relative antigen levels of VEGF detected by immunohistochemical examination almost coincided with the relative VEGF mRNA expression levels. Also, we examined the expression of basic fibroblast growth factor mRNA in the same tumor specimens. However, no significant correlation was found between the VEGF and basic fibroblast growth factor mRNA expression levels. We assessed the relationship between the VEGF121 mRNA expression level and the survival period in patients (n = 17) who underwent a curative operation at stage I of the disease. The median survival of the VEGF high-expression group was 8 months, and that of the VEGF low-expression group was 151 months. The 3- and 5-year survival rates of the high-expression group (n = 6) were 50.0% and 16.7%, respectively. On the other hand, those of the low expression group (n = 11) were 90.9% and 77.9%, respectively. The difference in survival between the two groups was significant (P < 0.05). Among eight cases of long-term survival beyond 5 years, seven cases had low or no VEGF121 mRNA expression. In contrast, among 18 cases with VEGF121 mRNA overexpression, 17 cases died due to recurrence. As a marker of tumor angiogenesis, the VEGF121 mRNA expression level may be a significant prognostic indicator of lung cancers in early stages.

The most ecologically successful and destructive termite species are those with both a nymph caste and an irreversibly wingless worker caste. The early developmental bifurcation separating these castes is widely accepted to be strictly environmentally determined. We present evidence that genotype also influences this process. Offspring from four different crosses of nymph- and worker-derived secondary reproductive individuals had strongly differentiated caste and sex ratios, despite uniform rearing conditions. These data fit an X-linked, one-locus-two-allele model. Of five possible genotypes, one was lethal, two resulted in workers, and two resulted in either nymphs or environmentally determined workers. Caste is thus controlled both by environment and by a complex genetic inheritance pattern.

genome. The duplicated genes comprised diverse categories related to social functions, including lipocalins (chemical communication), cellulases (wood digestion and social interaction), lysozymes (social immunity), geranylgeranyl diphosphate synthase (social defense), and a novel class of termite lineage-specific genes with unknown functions. Paralogous genes were often observed in tandem in the genome, but their expression patterns were highly variable, exhibiting caste biases. Some of the assayed duplicated genes were expressed in caste-specific organs, such as the accessory glands of the queen ovary and the frontal glands of soldier heads. We propose that gene duplication facilitates social evolution through regulatory diversification, leading to caste-biased expression and subfunctionalization and/or neofunctionalization conferring caste-specialized functions.