[DNA synthesis on the heterogeneous nuclear RNA template catalysed by DNA polymerase of avian myeloblastosis virus]. / Sintex DNK na matritse geterogennoi iadernoi RNK DNK-polimerazoi virusa mieloblastoza ptits

Template activity of nuclear pre-mRNA has been investigated in DNA-polymerase reaction. Active synthesis of DNA was demonstrated on pre-mRNA as a template in the absence of primer. A part of synthetic activity may be attributed to the traces of DNA present in the pre-mRNA preparation. Addition of oligo(dT)10 to the template stimulated the synthesis of DNA product due to transcription of heteropolymeric regions near the poly(A). The rate of DNA synthesis was different depending on the fraction of template used: the RNA extracted by hot phenol at 85 degrees showed higher template activity without adding of primer than the 65 degrees C fraction. On the contrary 65 degrees C pre-mRNA which is known to contain greater quantity of molecules with poly(A) at the 3'-end is more strongly stimulated by addition of oligo(dT). The nuclear RNA corresponding to the precursors of rRNAs extracted at 40 degrees C were not transcribed by the reverse transcriptase. The size of the DNA-product (about 7-8S in alkaline sucrose gradient) did not depend on the size of the template neither on the presence of oligo(dT)10 primer. The inhibition of the second DNA strand synthesis with actinomycin D had also no influence on the size of DNA-product.

[Physico-chemical characteristics of the DNA of the nuclear polyhedrosis virus of the moth Porthetria dispar L]. / Fiziko-khimicheskaia kharakteristika DNK virusa iadernogo poliédroza neparnogo shelkopriada Porthetria dispar L.

DNA preparations were obtained after dissolving the inclusion bodies, polyhedra virus particles, from the purified bundle virus of Porthetria dispar L. nuclear polyhedrosis. The DNA molecules in the preparations obtained are of different conformation and separate within the CsCl density gradient in the presence of ethidium bromide into supercoiled catenated and relaxed circular molecules (with the admixture of linear molecules). The circular DNA was studied by electron microscopy. The size of virus genome according to the data of reassociation kinetics of DNA is about 100 MD. Estimated on the basis of the values of buoyant density (p) and the melting temperature (Tmelt.) the content of guanine-cytosine pairs (GC pairs) in the viral DNA varies from 61 up to 65 mol%, and in the insect cell DNA--from 38 up to 40 mol%. The viral and cellular DNA are distinctly separated by centrifugation within the CsCl density gradient.

[A non-damaging procedure for DNA isolation from insect cell nuclei]. / Shchadiashchii metod vydeleniia DNK iz iader kletok nasekomykh.

A gentle procedure is described for DNA isolation from Galleria mellonella cell nuclei. Nuclei lysis was performed by SDS in final concentration of 3% which was followed by DNA extraction from chromatin by a stepwise rise of NaCl concentration up to 2.5 M. After removal of nuclei insoluble components by centrifugation the native DNA was purified using the hydroxyapatite column. The method proposed provides a higher yield of the native DNA as compared with the phenol-detergent method.

[Development of the molecular genetics of baculoviruses in Ukraine]. / Razvitie na Ukraine molekuliarnoi genetiki bakulovirusov.

Entomopathogenic baculoviruses are of interest from the standpoint of basic science and are of practical importance. The development of molecular biology and molecular genetics of baculoviruses in the Ukraine is considered in a brief review.

[Circular replicating baculovirus genome]. / Kol'tsevoi replitsiruiushchiisia bakulovirusnyi genom.

Free Malacosoma neustria nuclear polyhedrosis virus preparations contain nucleocapsids typical of Baculoviruses' morphology and size as well as long virus-like particles. Viral DNA is circular and covalently closed. Its preparations contain rings with single-stranded breaks, catenanes and circular dimers as well. Replicating pulse-labelled DNA preparations have been obtained from cells with the highest virus DNA synthesis. Theta-forms of replicating DNA are found in heavy fractions of sucrose gradients. Theta-forms, catenanes and circular dimers are discussed as intermediate molecules. Catenanes or (sometimes) circular dimers appear to form protein-containing complexes and long virus-like particles if the monomerization process is inhibited.

Macromolecular structure of nuclear polyhedrosis virus genome.

DNA preparations from nuclear polyhedrosis virus (NPV) of Galleria mellonella L. (GmL) were fractionated in high ionic strength neutral sucrose gradient. This procedure allowed a separation of supercoiled infectious DNA molecules with contour length of 48--52 microns from infectious open ring DNA molecule, and noninfectious linear DNA molecules of the same size. In addition a heterogeneity of supercoiled DNA molecules was detected. Covalently closed DNA molecules did not contain protein or ribonucleotide ligands which could be digested by pronase or pancreatic RNase treatment. It is concluded from data on the infectivity of different molecular forms of DNA and reassociation kinetics studies, that the genome of GmL NPV is a unique ring nucleotide sequence with a molecular weight of about 90--100 X 10(6).