Thyroliberin and its analog lacking hormonal properties stimulate respiratory center activity in the frog Rana temporaria

It has been shown that thyroliberin and its synthetic analogue PR-546 injected into the lymphatic sacs (4.10(-7)-4.10(-9) g/kg) or applied to the medulla oblongata in the bulbar frogs (4.10(-10)-4.10(-12) g/kg) significantly increase the rate of motor respiratory volleys in the hypoglossal nerve. In preparations with the irregular level of the activity of the respiratory center, these drugs enhanced stabilization of the initial level of the rhythm of motor respiratory discharges.     

Interaction of a cysteine-containing peptide with DNA

Cystine peptide dimer (Lys-Gly-Val-Cys-Val-N2H2Dns)2 with S-S bridge was synthesized and its interactions with DNA and synthetic polynucleotides have been studied by optical spectroscopy methods. By recording fluorescent titration curves we have shown that the affinity of the peptide to different synthetic polynucleotides decreases in the order: poly(dG).poly(dC) greater than poly(dA).poly(dT) greater than poly(dGC).poly(dGC). The stability of complexes to increasing concentrations of NaCl diminishes in the same order. The association constant is about 20-fold greater for peptide binding to poly(dG).poly(dC) than to poly(dA).poly(dT). By using circular dichroism and fluorescence measurements we have shown that the peptide competes for the binding sites on DNA with two minor-groove binding antibiotics--distamycin A and sybiromycin. These results have suggested that the peptide also binds in the DNA minor groove. Investigation of the interactions between such peptides and DNA may be useful for constructing ligands with combined specificity to DNA.     

Interaction of trivaline with single-stranded polyribonucleotides]

Binding of tripeptide H-Val3-(NH)2-Dns (TVP) to polyribonucleotides was studied by fluorescence methods, circular and flow linear dichroism, equilibrium dialysis and electron microscopy. It was found that TVP binds to poly(U) in monomer, dimer and tetramer forms with binding constants of about 10(3), 40, 18.10(4) M, respectively. The cooperativity parameter for peptide dimer binding is 2000. The peptide forms tetramer complexes with poly(A), poly(C), poly(G) also. The formation of a complex between the peptide tetramer and nucleic acid is accompanied by a significant increase in the fluorescence intensity. The cooperative binding of TVP dimers to poly(U), poly(A), poly(C) is accompanied by a dramatic decrease in the flexibility of polynucleotide chains. However, it has a small effect (if any) on the flexibility of the poly(G) chain. The observed similarity of thermodynamic, optical and hydrodynamic++ properties of TVP complexes with single-stranded and double-stranded nucleic acids may reflect a similarity in the geometries of peptide complexes with nucleic acids. Electron microscopy studies show that peptide binding to poly(U) and dsDNA leads to compactization of the nucleic acids caused by interaction between the peptide tetramers bound to a nucleic acid. At the first stage of the compactization process the well-organized rod-like particles are formed, each consisting of one or more single-stranded polynucleotide fibers. Increasing the peptide concentration stimulates a side-by-side association and folding of the rods with the formation of macromolecular "leech-like" structures with the thickness of 20-50 nm.     

Stereochemistry and kinetics of interaction with DNA of the antineoplastic antibiotic olivomycin

The kinetics of interaction of antitumor glycoside antibiotic olivomycin with DNA has been investigated. The existence of two relaxation times in the experimental kinetics curves indicates that two types of antibiotic--DNA complex are formed. We have measured the rate constants of association and dissociation processes and determined their temperature dependences. It is suggested, that one of the complex form results from nonspecific interaction between glycoside residues of the antibiotic molecule and sugar-phosphate backbone of DNA whereas the other type of complex exhibits a pronounced specificity for GC-rich regions on DNA. The binding specificity probably results from formation of a H-bond between the antibiotic chromophore ring and guanine 2-amino group. A stereochemical model for olivomycin-DNA complex is proposed. According to this model the antibiotic chromophore and glycoside residues are located in the narrow groove of DNA.     

Magnetic interaction of manganese with pheophytin anion-radical and chlorophyll cation-radical in reaction centers of the photosystem II

The influence of Mn on saturation curves of ESR spectra of Ph(-) and P(+)(680) at 1-200K in samples with different content of Mn has been studied. An analysis of these data and those on photoinduced changes of fluorescence yield of chlorophyll leads to the conclusion that the Mn-containing centre in Photosystem 2 is a cluster of 4 Mn atoms, two of which can be replaced by Mg(2+) or any other divalent metal. The distances between Mn Na Ph as well as between Mn and P(680) have been estimated.     

Phylogeny of the order Rodentia inferred from structural analysis of short retrotransposon B1

A large-scale study of short retroposon (SINE) B1 has been conducted in the genome of rodents from most of the known families of this mammalian order. The B1 nucleotide sequences of rodents from different families exhibited a number of characteristic features including substitutions, deletions, and tandem duplications. Comparing the distribution of these features among the rodent families, the currently discussed phylogenetic relationships were tested. The results of analysis indicated (1) an early divergence of Sciuridae and related families (Aplodontidae and Gliridae) from the other rodents; (2) a possible subsequent divergence of beavers (Castoridae); (3) a monophyletic origin of the group Hystricognathi, which includes several families, such as porcupines (Hystricidae) and guinea pigs (Caviidae); (4) a possible monophyletic origin of the group formed by the remaining families, including six families of mouselike rodents (Myodonta). Various approaches to the use of short retroposons for phylogenetic studies are discussed.     

A new pentanucleotide STR-marker, located in the intron of the ING1 tumor suppressor gene and its allelic polymorphism

DNA samples of unrelated subjects from the Volga-Ural region of Russia were examined to study allele polymorphism of the pentanucleotide repeat (TTGTG)8 localized to an intron of the tumor suppressor gene ING1. STR marker was registered in the EMBL database with the accession number AJ277387. In a sample of 119 individuals, three pentanucleotide alleles consisting of seven, eight, and nine repeated monomers were revealed. The allele frequencies were 0.24, 0.74, and 0.02, respectively. Heterozygosity was 0.45. On the basis of these data, the repeat can be regarded as a polymorphic STR marker for the ING1 gene and used in population and clinical studies.     

Evolutionarily-conserved gene CKAP2,located in region 13q14.3 of the human genome, is frequently rearranged in various tumors

The human CKAP2 gene, which is involved in diffuse large B-cell lymphomas, was localized via screening the GeneBridge 4 somatic cell radiation hybrid panel by means of the polymerase chain reaction (PCR). The CKAP2 gene was mapped between the WI-15460 and WI-3673 markers at the boundary between regions 13q14.3 and 13q21.1, at the distance of 14.39 cR (with 4.8 cR per cM) from the WI-5867 framework marker (lod score > 2.26). The human CKAP2 gene displayed high homology to mouse and rat expressed orthologs, A CKAP2-like sequence was found in human chromosome 14 and assumed to be a pseudogene resulting from duplication and subsequent mutations of the CKAP2 gene on chromosome 13. A possible role of the CKAP2 gene in oncogenesis associated with deletions and rearrangements of region 13q14.3-21.1 is discussed.     

Effect of the gene for bacterial hemoglobin vhb on the effectiveness of the process of Escherichia coli-Streptomyces interspecies conjugation and production of antibiotics in streptomycetes

The bacterial hemoglobin vhb gene was cloned from sliding bacterium Vitreoscilla sp. as an element of the system ensuring survival of this microorganism in an environment that contains insufficient amount of oxygen. The vhb gene was transferred from Escherichia coli to some Streptomyces strains, producers of antibiotics, by the method of intergeneric conjugation using conjugative-integrative plasmid vectors pIH1 and pCH2. The stability of plasmid DNA inheritance was analyzed in the genomes of exconjugants. A positive effect of the vhb gene on processes of conjugation and antibiotic production in a number of examined strains was shown.     

Haplotype of Y-chromosomes in the Central Asia population

The distribution of alleles and haplotypes of three diallellic Y-specific loci (YAP, DYF155S2, and Tat) in the populations of Kyrgyz, Uzbeks and Tajiks was analyzed. In Kyrgyzes and Uzbeks, a relatively high frequency of the DYF155S2 deletion (20 and 12.5%, respectively) and the C allele at the Tat locus (11.2 and 8.3%, respectively) were revealed. In the populations of southern Kyrgyzes and Uzbeks, two chromosomes carrying the YAP+ allele were detected. In both cases the YAP+ allele was found within the YAP+/DYF155S2+/TatT haplotype. The Tajik population was monomorphic in respect to the polymorphisms studied. The Tajiks demonstrated the presence of only the YAP-/DYF155S2+/TatT haplotype. This haplotype appeared to be most frequent in Kyrgyz (78.8%) and Uzbeks (83.3%). The question on the origin and the distribution of Y-chromosome variants in Eurasia are discussed.