Using wood mice (Apodemus speciosus) captured in the wild in Niigata, we analysed the proportion of various endocrine cells in pancreatic islets for both immunohistochemical and microscopic characteristics. In both the dorsal and ventral portions of the pancreas, the centre of the pancreatic islets was occupied predominantly by insulin-positive (B) cells, surrounded by glucagon-positive (A), somatostatin-positive (D), and pancreatic-polypeptide-positive (PP) cells. Although the proportions of the various endocrine cells in pancreatic islets varied from one mouse to the next, in most animals B cells accounted for more than half of all endocrine cells. Dorsal and ventral portions of the pancreas differed in the proportions of various endocrine cells, specifically, in the A-to-PP cell ratio: the proportion of PP cells higher in the ventral portion. The same tendency is seen in humans, rats and mice. Microscopic examinations revealed morphologically distinct secretory granules in A, B and D cells. The morphology of these granules was similar that of secretory granules found in rats and mice.

The genus Dendrobium, one of the largest genera in Orchidaceae, exhibits enormous vegetative diversification. Such a situation has hindered the establishment of consistent classification systems. To clarify phylogenetic relationships in Dendrobium section Dendrobium and allied groups, we performed molecular phylogenetic analyses of 210 taxa. The results showed that many sections are not monophyletic. Most of the morphological characters that have been believed to reflect phylogenetic relationships are, in fact, the results of convergence. Consequently, recircumscription of the infrageneric classification is required.

Genus Dendrobium (Orchidaceae) contains numerous species. Phylogenetic analyses based on morphological characteristics and DNA sequences indicated that this genus is divided into two major groups: Asian and Australasian clades. On the other hand, little is known about the phytochemical differences and similarities among the species in each clade. In this study, we selected 18 Dendrobium species (11 from the Asian clade and 7 from the Australasian clade) and constructed HPLC profiles, arrays composed of relative intensity of the chromatographic peaks. Next, orthogonal partial least square discriminant analysis (OPLS-DA) was applied to the profile matrix to classify Dendrobium species into the Asian and Australasian clades in order to identify the peaks that significantly contribute to the class separation. In the end, two phenanthrenes, 4,9-dimethoxyphenanthrene-2,5-diol 1 and 1,5-dimethoxyphenanthrene-2,7-diol 2, which contributed to the class separation, were isolated from the HPLC peaks. The existence of 2 was limited to the genetically related Australasian species.

Detailed structural analysis of 6-thioguanosine (6TGs) in relation to its tautomerization and sugar conformation is performed in the gas phase using UV and IR spectroscopy combined with ab initio calculations. We have observed a thiol tautomer of 6TGs with its sugar moiety in the syn conformation that is stabilized by a strong intramolecular Hbonding between O5′H of the sugar and N3 atom of the guanine moiety. This observation is consistent with previous results for guanosine (Gs) in which the corresponding enol form is solely detected. We have also identified a monohydrate of 6TGs consisting of a thiol tautomer with the water linking guanine moiety and sugar OH group. It is demonstrated that hydration behavior of 6TGs is significantly different from that of Gs as a result of a weaker H-bonding ability of the thiol group.