Isolation of high molecular weight eukaryotic DNA with the use of potassium acetate

The simple technique for isolation of high-molecular eucaryotic DNA has been proposed. It includes cell or nuclei lysates by sodium dodecylsulfate in the presence of pronase, proteins precipitation by potassium acetate, DNA precipitation by ethanol. The DNA isolated by this technique is easily cleaved by restriction endonucleases and can be used for analysis of the unique genes by blot-hybridization. The yield of DNA is similar or somewhat higher than that in case of using the standard methods including phenol extraction or phenol-chloroform extraction.     

Mathematical model of histamine bronchospasm]

A mathematical model of changes in histamine concentration in the wall of human bronchiole was constructed. The parameters of the model adequately characterize the state of patients with bronchial asthma.     

Evolutionary relationships of eukaryotic kingdoms

The evolutionary relationships of four eukaryotic kingdoms—Animalia, Plantae, Fungi, and Protista—remain unclear. In particular, statistical support for the closeness of animals to fungi rather than to plants is lacking, and a preferred branching order of these and other eukaryotic lineages is still controversial even though molecular sequences from diverse eukaryotic taxa have been analyzed. We report a statistical analysis of 214 sequences of nuclear small-subunit ribosomal RNA (srRNA) gene undertaken to clarify these evolutionary relationships. We have considered the variability of substitution rates and the nonindependence of nucleotide substitution across sites in the srRNA gene in testing alternative hypotheses regarding the branching patterns of eukaryote phylogeny. We find that the rates of evolution among sites in the srRNA sequences vary substantially and are approximately gamma distributed with size and shape parameter equal to 0.76. Our results suggest that (1) the animals and true fungi are indeed closer to each other than to any other crown group in the eukaryote tree, (2) red algae are the closest relatives of animals, true fungi, and green plants, and (3) the heterokonts and alveolates probably evolved prior to the divergence of red algae and animal-fungus-green-plant lineages. Furthermore, our analyses indicate that the branching order of the eukaryotic lineages that diverged prior to the evolution of alveolates may be generally difficult to resolve with the srRNA sequence data.     

The role ofSaccharomyces cerevisiae Cdc40p in DNA replication and mitotic spindle formation and/or maintenance

Successful progression through the cell cycle requires the coupling of mitotic spindle formation to DNA replication. In this report we present evidence suggesting that, inSaccharomyces cerevisiae, theCDC40 gene product is required to regulate both DNA replication and mitotic spindle formation. The deduced amino acid sequence ofCDC40 (455 amino acids) contains four copies of a β-transducin-like repeat. Cdc40p is essential only at elevated temperatures, as a complete deletion or a truncated protein (deletion of the C-terminal 217 amino acids in thecdc40-1 allele) results in normal vegetative growth at 23°C, and cell cycle arrest at 36°C. In the mitotic cell cycle Cdc40p is apparently required for at least two steps: (1) for entry into S phase (neither DNA synthesis, nor mitotic spindle formation occurs at 36°C and (2) for completion of S-phase (cdc40::LEU2 cells cannot complete the cell cycle when returned to the permissive temperature in the presence of hydroxyurea). The role of Cdc40p as a regulatory protein linking DNA synthesis, spindle assembly/maintenance, and maturation promoting factor (MPF) activity is discussed.