The length of DNA determines the degree of regularity of crystals of the cro-repressor complex

The DNA-cro-repressor complex crystals have been obtained, five DNA fragments of the same nucleotide sequence and different length being used. The rotation function for crystals of complexes with hexamer (pGpT)3 . (pApC)3 and with octamer (pGpT)3 . (pApC)3 have been calculated. The order of cro-DNA complex crystals is shown to vary with DNA length, the crystal of the complex with octamer being the most perfect among all investigated complexes.     

Expression of human growth hormone in cultured mouse fibroblasts

The new system for the transfer and expression of foreign genes based on retroviral vectors pPS-neo, conferring neomycin resistance was constructed. The BALB/c mouse cell lines producing highly active human growth hormone (more than 7 micrograms/ml into culture medium) were constructed using these vectors. An antibody column was used to purify the growth hormone from cell culture medium. Possibilities of producers to be applied for gene therapy are discussed.     

BsoAI--a new site specific endonuclease from Bacillus coagulans

A new site-specific endonuclease was detected in toluene lysates of Bacillus coagulans AUCM B-732 and designated as BcoAI. The enzyme was purified by fractionation of the cell-free extract in the two-phase PEG/dextran system followed by chromatography on DEAE-sepharose and phosphocellulose and shown to be free of nonspecific nucleases and phosphatases. BcoAI has three cleavage sites on lambda DNA, but does not cleave SV40, pBR322 and pUC19 DNA. BcoAI recognizes the sequence 5' CAC decreases GTG 3' on double-stranded DNA and cleaves it as indicated by the arrow to yield blunt-ended DNA fragments. Thus, BcoAI is a true isoschizomer of PmaCI from Pseudomonas maltophila C.     

Simple methods of enzymatic amplification of DNA for clinical practice]

The methods for enzymatic DNA amplification in vitro that allow to avoid the step of preliminary DNA extraction and purification are proposed. Lysates of blood cells in the solution or immobilized on the nylon membrane filters and dried blood spots on the filter paper blotters were used directly in amplification permitting one to solve the problems of adapting the method of polymerase chain reaction in clinical practice, for instance, in massive screening of genome mutations, viral infections etc.     

Localization of acid phosphatase in Saccharomyces cerevisiae and its export into culture media depends on the type of the N-terminal signal peptide

The aim of this work was to study the character of intracellular distribution and efficiency of yeast acid phosphatase export depending on the type of the N-terminal signal peptide used. A number of plasmids carrying the acid phosphatase genes with different signal peptides sequences was constructed. The main site of the enzyme accumulation for the variant containing its own acid phosphatase signal peptide was the periplasm. Approximately the same pattern was observed when the hybrid signal peptide consisting of acid phosphatase signal peptide and alpha-factor preprosegment tandem was used. Unlike the above-mentioned systems the strain carrying acid phosphatase under the control of alpha factor preprosegment was able to export the enzyme into the culture medium. The experiments have shown the possibility of changing the final localization of secretory proteins by replacing the N-terminal signal peptide.     

Production of DON-related trichothecenes byFusarium graminearum Schw from Krasnodarski krai of the USSR

34Fusarium graminearum Schw isolates produced 4-deoxynivalenol to form significant amounts of 4, 7 — dideoxynivalenol and lesser amounts of 4 — deoxynivalenol monoacetates on grain substratesin vitro. This is the first report on the capability a large group of naturally occurring isolates to produce 4,7-dideoxynivalenol. The average levels of 4,7-dideoxynivalenol on rice, corn, barley, and wheat as a substrate were respectively 26.8, 14.0, 12.8, and 10.5% of the level of 4-deoxynivalenol. 4, 7 — dideoxynivalenol was present in all examined naturally contaminated wheat kernel samples at levels of 1.7 to 7.9% of the level of 4-deoxynivalenol. These findings suggest that more attention should be given to the occurrence of 4,7-dideoxynivalenol in cereals.     

Variation in the ribosomal internal transcribed spacers (ITS1 and ITS2) among eight taxa of the Mimulus guttatus species complex

The internal transcribed spacer region (ITS1 and ITS2) of the 18S-25S nuclear ribosomal DNA sequence and the intervening 5.8S region were sequenced from three individuals in each of eight taxa of the Mimulus guttatus species complex. Three discrete variants, or "types," of ITS sequences were found, among which 30%-40% of sites differed, compared with 1%-2% within types. Dot plots indicate that these types were not related by conspicuous rearrangements or inversions. More than one ITS type was often found in the same taxon, and two of three ITS types span species boundaries, indicating their presence prior to speciation. These ITS sequences showed essentially no positional homology with the nearest sequenced relative, tomato. In contrast, the 5.8S region was relatively unvaried, with 8 of 162 sites varied in the sample among all eight taxa. The phylogeny inferred by the most common ITS sequence type, rooted by the two other ITS types, agreed with isozymes in showing the distinctness of M. nudatus, M. laciniatus, and M. tilingii from the other five taxa.