The mass spectra of 10,10-dimethyl-9,10-dihydro-10-sila-2-azaanthracenes with heterocyclic substituents at C9

The major pathways for the fragmentation of dihydrosilaazaanthracenes, containing an azetidine substituent, spiro-β-lactam ring, or spirotetrahydrofuryl residue at C9 upon electron impact are related to the presence of these rings. The azetidine ring may be eliminated as a radical or by splitting "in half" to give [M-Me]+ ions. Splitting of the spiro-β-lactam ring "in half" leads to the two strongest ions M+. The loss of the tetrahydrofuryl ring leads to ions of 9-methylene- and 9-oxosilaazaanthracenes. The dlmethylsilyl group loses a methyl radical at various stages of the decomposition. © 1990 Plenum Publishing Corporation

Phylogeny and phylogeography of the roaches, genus Rutilus (Cyprinidae), at the Eastern part of its range as inferred from mtDNA analysis

The genus Rutilus is a widely distributed lineage of cyprinids and ranges from West Europe to East Siberia. Although matrilineal phylogeny and phylogeography of western species were already studied, roaches from remaining part of the range were not examined. Phylogenetic analysis based on cytochrome b sequences detected the following three major phylogenetic clades: (i) R. frisii, (ii) R. rutilus s. str., and (iii) group of six Ponto–Caspian taxa: R. caspicus, R. heckelii, R. rutilus aralensis, R. rutilus lacustris, R. schelkovnikovi, and R. stoumboudae. Our results suggest that these “species” within Ponto–Caspian clade could be a single species (R. lacustris by priority of description). The Ponto–Caspian clade is most widely distributed among others and covers the freshwaters from the Aegean Sea basin to Laptev Sea tributaries. Both R. rutilus s. str. and Ponto–Caspian clades sympatrically occur in Black Sea and Caspian Sea basins, Azov Sea itself, and even in drainage of White Sea. The vastest zone of contact (approximately 1700 km) was detected in the Volga basin. The spatial pattern of haplotype diversity and the shape of haplotype network argued for multiple refugia in Ponto–Caspian region as well as a rapid post-glacial colonization of Volga River and Siberia