A time-diagnostic positive excursion (∼1‰) of carbon isotope ratio (δ13C) recorded in organic matter from the Middle Turonian (Late Cretaceous) clastic sequences in Japan and Russian Far East provides inter-regionally recognizable chemostratigraphic keybed at 90.7 Ma. Compilation of recent studies on carbon-isotope stratigraphy for this region revealed that the δ13C event is located in the middle of gradual∼1.5‰ negative shift above the prominent Cenomanian/Turonian boundary δ13C “spike”. Limited occurrences of cosmopolitan age-indicative ammonoid species, Collignoniceras woollgari revealed that the range of this species encompasses the δ13C event horizon confirming its utility as an international chemostratigraphic keybed, whereas the common occurrence of Inoceramus hobetsensis across the δ13C event benefits identifying this important marker horizon.
(Communicated by Tatsuro MATSUMOTO, M. J. A., June 10, 2003)
We found quartz diorite veins (up to 5 mm thick), composed mainly of plagioclase and quartz, in a plagioclase-bearing spinel lherzolite xenolith in alkali basalt from Tallante, Southern Spain. The quartz diorite veins are coarse-grained, the average grain size being 0.5 mm, and have thin orthopyroxenite rim along olivine wall. Thinner veins free of quartz and composed solely of plagioclase with orthopyroxene selvage are much more common in other xenoliths from Tallante. The involved melt was strongly reactive with olivine to form orthopyroxene, which can protect against further reaction. This suggests how the silica-oversaturated melts, after supplied from downgoing slabs, can move through peridotite and reach the shallow mantle with preserving the silica-oversaturated character. The armor of orthopyroxenite is of vital importance for the melt to keep its silica-oversaturated character within peridotite. Precipitation of orthopyroxene combined with olivine consumption somewhat controls the general chemical trend of adakite. Orthopyroxenite vein network at the expense of olivine is expected to be common as fossil conduits within the mantle wedge. This kind of orthopyroxenite has contributed to Si-enrichment of the mantle wedge.
(Communicated by Ikuo KUSHIRO, M. J. A., June 10, 2003)
Partially normalized complementary DNA (cDNA) libraries were generated from root and leaf tissues of a diploid tobacco species, Nicotiana sylvestris. Single-pass sequences were obtained from a total of 13, 019 cDNA clones and were assembled into 6, 513 non-redundant cDNA groups. We estimate that these cDNA sequences represent approximately 3, 500 unique tobacco genes. The EST database described here will become a valuable resource for future research using Nicotiana species.
(Communicated by Yasuyuki YAMADA, M. J. A., June 10, 2003)
This paper describes the reclassification and molecular evolution of phytoplasmas based on nucleotide sequence analysis of the 16S rRNA and 16/23S spacer region. Analyses of the secondary structure of 16S rRNA among 23 phytoplasmas revealed 308 polymorphisms of which two thirds were located in nine highly variable regions. The 16/23S spacer region comprised two highly conserved regions and a highly conserved tRNAIle gene. Nucleotide deletion/insertions of various lengths occurred only between the highly conserved regions, resulting in 16/23S spacer regions with varying lengths among different phytoplasmas. Phylogenetic analysis on the alignments of secondary structure of 16S rRNA established a tree with ten major groups that had high confidence values. The branching patterns and differences in the 16S rRNA sequence homology greater than 2.5% established 10 major groups among the 23 phytoplasmas. We hypothesize that phytoplasmas evolved independently from a common ancestor into two branches: one branch consisting of the aster yellows and stolbur groups, and the others as a second branch.
(Communicated by Eishiro SHIKATA, M. J. A., June 10, 2003)
Following the direction of our previous publication (Amano, N., Tsuji, K., and Suzuki, M. (2003) Proc. Japan Acad. 79B, 131-136), promoter and gene-coding regions, and types of transcription units (i.e. operons and independently regulated genes) were theoretically identified for Thermoplasma volcanium. Possibly reflecting the optimum growth temperature lower than that of Pyrococcus sp. OT3, signals for transcription and translation were found to be weaker, and the degree of differentiating gene-coding regions was lesser. Nevertheless, with some modification of the strategy, genes were identified with a similarly high precision. Some notable characteristics of the identified promoter sequences are discussed.
(Communicated by Masanori OTSUKA, M. J. A., June 10, 2003)
We investigated the possible involvement of mast cells in acute hepatic injury induced by galactosamine (GalN, 20 mg/mouse) and lipopolysaccharide (LPS, 15 ng/mouse) (GalN/LPS) in mice. Histidine decarboxylase (HDC) mRNA expression in the liver as well as serum ALT level was increased with time after GalN/LPS treatment. Steroid anti-inflammatory agent (dexamethasone), histamine H1 receptor antagonists (diphenhydramine and pyrilamine), histamine H2 receptor antagonists (cimetidine and ranitidine) and 5-HT2 receptor antagonist (ketanserin) were effective in reducing the ALT level at 8 h after the treatment with GalN/LPS. Furthermore, dexamethasone, diphenhydramine and cimetidine inhibited the increase in hepatic HDC mRNA level. The increase in ALT level by GalN/LPS was much lower in mast cell-deficient mice than in the congenic normal mice. Diphenhydramine further inhibited ALT level in response to GalN/LPS in mast cell-deficient mice. Our data suggest that mast cells play an important role in the development of hepatic injury induced by GalN/LPS, and suggest that histamine and 5-HT released from mast cells and other cells are involved in this model.
(Communicated by Masanori OTSUKA, M. J. A., June 10, 2003)
For the identification of the botanical origin of licorice (ML-44, N-99) stored in Shosoin, the Imperial Storehouse in the city of Nara since 756AD, we made genetic and chemical analyses in comparison with 205 and 117, respectively, authentic samples of licorice roots derived from Glycyrrhiza uralensis, G. glabra and G. inflata. Referring to the experimental results of the genetic analysis study of internal transcribed spacer (ITS) on nuclear ribosomal DNA (nrDNA) of the above three species of licorice, the contents of glycyrrhizin and five main flavonoids, and their scattering pattern of occurrence, Shosoin-licorice was finally identified to be the root of G. uralensis.
(Contributed by Shoji SHIBATA, M. J. A., June 10, 2003)