The stable RNAs, whose sequences are homologous to 10Sa RNA of Escherichia coli, have been isolated from Mycoplasma capricolum and Bacillus subtilis, both belonging to the Gram-positive bacterial group. The total nucleotide sequences of the RNAs have been determined by partial RNA sequencing and DNA sequencing of their genes. A comparison of the sequences, together with those of other bacterial 10Sa RNAs so far known, has shown that the 5'- and 3'-end sequences are well conserved among species, while the central parts reveal little homologies. Unexpectedly, the conserved 5'- and 3'-regions can be folded in a common tRNA-like structure containing an amino acid-acceptor stem and a T phi C-stem/loop. The 3'-terminal CCA sequence of B.subtilis 10Sa RNA is not encoded on the DNA, but is added after transcription. Furthermore, the RNA is aminoacylatable with alanine in vitro, and binds to the 70S ribosome in vivo.

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The 16S rRNA gene sequences were determined for type strains of 21 Bifidobacterium species. A phylogenetic tree was constructed using the determined sequences and sequences from DNA databases, which contain the sequences of 11 type strains of Bifidobacterium species and 11 strains of related genera. All species of the genus Bifidobacterium and Gardnerella vaginalis ATCC 14018 belonged to a cluster phylogenetically distinct from the other genera. The cluster was divided into two subclusters: subcluster 1 composed of most species of Bifidobacterium and G. vaginalis, and subcluster 2 consisting of two species, B. denticolens and B. inopinatum; both of which were isolated from human dental caries. In the genus Bifi dobacterium, four groups of species are known to be moderately to highly related by DNA-DNA hybridiza -tion. The four groups of species exhibited more than 99% similarity among their 16S rDNA sequences within each group. These results indicated that species with around 99% or more similarity in their 16S rDNA sequences should be confirmed for species identities.

We analysed the long‐term trend and interannual variability in summer (JJA) precipitation over eastern Siberia (90°–140°E, 50°–70°N) for the period 1979–2007. An increasing trend in summer precipitation was observed over large areas (Yenisei and Lena river basins) of eastern Siberia. Summer mean 850‐hPa geopotential height decreased from Siberia to the marginal seas north of Siberia, with the largest decreases occurring over the northern part of eastern Siberia, while increasing trends were found around Mongolia, inducing a significant increase in westerly moisture flux and its convergence over eastern Siberia. Empirical orthogonal function (EOF) analysis of detrended summer precipitation revealed the leading modes of the interannual variability. The first leading mode (EOF1) represents interannual variation around the central Siberian Plateau and the middle reaches of the Lena river basin, related to the enhancement of a low‐level cyclonic circulation centred on 65°N, 100°E around eastern Siberia. The circulation pattern of EOF1 closely matches the trend pattern over Siberia, indicating that a deeper quasi‐stationary trough appears with increasing frequency in recent decades. The second leading mode (EOF2) shows a dipole pattern between the middle reaches of the Lena river basin and the western part of the Central Siberian Plateau. Wet summers in the Lena river basin are related to a stationary trough centred at around 60°N, 130°E. These leading patterns are related to the change in position of the stationary trough and the ridge of the wave train structure along the Arctic polar jet across the northern Eurasian continent.

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