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S Zadrazil

Publications and source records attributed to S Zadrazil.

At least 19 recordsLinked to original sources
PubMed1988

Expression and properties of prochymosin derivatives containing extensions of various length in the pro-part.

A series of hybrid prochymosin derivatives containing portions of the simian virus 40 small-t antigen in the pro-part was constructed. Portions comprising 93, 63, 47, 12, and 1 amino acid (aa) from the N terminus of the small-t antigen were separately fused via eight polylinker-encoded amino acids to a prochymosin product commencing with the 5th aa of the pro-part. All the DNAs coding for the hybrid proteins were put under pL-promoter control in the expression constructs. Expression revealed that only fusion of the 47-aa or 12-aa stretch of the small-t antigen to prochymosin gave stable protein products and that only the latter one allowed the hybrid prochymosin to be activated to chymosin. The products containing 93 aa and 63 aa of small-t antigen were unstable and degraded. Complete removal of the small-t antigen portion led to mRNA instability, probably owing to inefficient initiation of translation.

Base Sequence↗
PubMed1987

Tolerated variations in a genome: the case of closely related Bacillus phages PZA, phi 29 and phi 15--a review.

Restriction-site analysis was used to estimate the relationship of bacteriophages PZA, phi 29 and phi 15. Complete nucleotide sequences of PZA and luminal diameter 29 genomes were compared and tolerated variations were assessed. Most of the base-pair changes are silent nucleotide substitutions in the third position of codons but amino acid changing substitutions are also observed. The terminal portions of the phage genomes diverged faster than their central parts. Gene mutations in phage PZA were induced by hydroxylamine and their frequency was compared with the evolutionary mutability.

Bacillus↗
PubMed1987

Lack of synthesis of pentamer IgM in Xenopus oocytes after injection of poly(A)+ RNA from hybridoma cells.

Total poly(A)+ RNA was isolated from B cell hybridomas producing monoclonal antibodies of the IgM class specific for sheep red blood cells. These RNAs were microinjected into Xenopus oocytes and the translation products were analyzed. Unlike the hybridoma cells, the oocytes synthetized only the light chains and oligomer IgM, but evidence for assembly of functional pentamer IgM was not obtained. The possible reasons for these differences are discussed.

Animals↗
PubMed1987

Subcloning of prochymosin cDNA for Plac controlled expression.

Two overlapping segments of prochymosin cDNA clones (Liebscher et al., 1985) were used to construct plasmids that expressed an activable zymogen product and thus verified the integrity of the reverse transcripts. The pUC9 vector was used for the expression, under the control of the lac promoter. The expression product (a fused protein consisting of the N-terminus of beta-galactosidase, a polylinker-coded peptide and prochymosin from its 5th amino acid) displayed, upon activation by the usual procedure, the properties of calf chymosin. The active product was identified by milk-clotting tests, "caseinography" and protein electrophoresis of immunoprecipitates. The "boxing" of prochymosin cDNA in the constructed plasmids makes them a versatile source of this cDNA for other expression constructs.

Chymosin↗
PubMed1985

Comparison of genomes of closely related phages phi 29, phi 15 and PZA using a rapid method of parallel physical mapping.

The DNAs of phages phi 29, phi 15 and PZA of Bacillus subtilis were analysed with restriction enzymes EcoRI, HpaI and HindIII. A method was used which permits parallel physical mapping of all three phages, from both ends of their linear genomes. The method is based on transfer of partially digested DNA to DBM paper and sequential hybridization with labelled terminal fragments. It follows from the comparison of the physical maps that phages phi 29, phi 15 and PZA are closely related and that they probably have arisen from a common ancestor by accumulation of point mutations.

Bacillus subtilis↗
PubMed1985

Isolation, partial characterization and translation of mRNAs for chymosin and pepsin, the two main aspartyl proteinases of bovine stomach.

Poly(A) RNA from the mucosa of the fundal region of the fourth stomach of suckling calf and adult cattle was isolated by the phenol or guanidine thiocyanate procedure. The mRNAs for chymosin and pepsin were present in the 15S fraction of poly(A) RNA. They were active both in cell-free translation systems and in oocytes of Xenopus laevis and directed the synthesis of either chymosin or pepsin precursor, depending upon the age of the donor animal. In the reticulocyte and wheat germ system only preprochymosin or prepepsinogen were synthesized. In the oocyte system only the synthesis and secretion of prochymosin or pepsinogen could be detected. Both proenzymes, prochymosin and pepsinogen, present in oocytes or secreted into the medium, were converted to active enzymes, chymosin and pepsin, respectively, at pH 3.0, as shown by their proteolytic and milk-clotting activity.

Abomasum↗
PubMed1984

Comparison of Bacillus subtilis phages PZA, phi 29 and phi 15.

Morphologically identical phages PZA, PZE , phi 29, and phi 15 can be distinguished by the neutralization test with rabbit antisera and by host range specificity. Each member of this phage group contains 18 kb double-stranded linear DNA carrying proteins covalently attached to its 5' ends. Physical maps of their DNA constructed with the use of restriction endonucleases EcoRI, HpaI, HindIII, BspRI, and XbaI and DNA-DNA hybridization experiments show a closer relationship between phi 29 and PZE than between phi 29 and phi 15 or phi 29 and PZA. phi 15 is closer to PZA than to phi 29. This conclusion is supported by analysis of differential denaturation profiles of the phage DNAs. Sequencing of selected parts of phi 29 and PZA DNAs reveals 93% homology with a preference for synonymous base replacements (silent mutations) randomly distributed in the coding regions. Using promoter-probe plasmid pPV33 -H the region functioning as a promoter in E. coli was localized on the smallest EcoRI fragment of PZA and phi 29 DNAs. Comparison of the nucleotide sequence of this region with known promoters of B. subtilis shows extensive homologies with at least two types of promoters of different specificities, namely those recognized by factors sigma 28 of B. subtilis and sigma gp28 of phage SPO1 . These promoter-like regions overlap and the whole sequence is conserved in both phages.

Bacillus subtilis↗
PubMed1982

Restriction and modification in Bacillus subtilis 168. Regulation of hsrM(nonB) expression in spoOA mutants and effects on permissiveness for phi15 and phi105 phages.

Gene hsr M (nonB) of Bacillus subtilis 168, causing non-permissiveness to phage SP10 (Saito et al. 1979) and reduced plating efficiency of unmodified phage phi105, is responsible for non-permissiveness of B. subtilis 168 for phages phi15 and PZA. Upon transformation to sporulation deficiency (allele spoOA) B. subtilis 168 becomes permissive for phi15 and PZA and loses the ability to restrict phi105. spoOA str-1 double transformants of B. subtilis 168, however, retain the restriction 168 and non-permissiveness for phi15 and PZA phages, in spite of their Spo- phenotype. Therefore it appears that a functional product of the spoOA gene is required for expression of gene hsrM in wild-type bacteria, but is not essential in streptomycin-resistant bacteria. Phage genomes (PZA) were trapped in spores of the restriction deficient strain with much higher efficiency than in the wild-type.

Bacillus subtilis↗
PubMed1982

Transfer of immunological tolerance by means of RNA.

Ribonucleic acid extracts were isolated from the lymph nodes and spleens of mice bearing tolerated skin allografts for long periods after neonatal tolerance induction. Lymphoid cells from control, untreated mice were incubated in vitro with these RNA extracts and then transferred into normal newborn mice. Skin allografts applied to the RNA-treated animals tn adult life survived significantly longer when compared with the non-treated mice or mice treated with RNA extracted from normal, non-tolerant mice. The results indicate that RNA from tolerant animals, like suppressor cells, is effective in prolonging skin allograft survival.

Animals↗
PubMed1981

Induction of specific cell-mediated cytoxicity in vitro by means of RNA isolated from allografted mice.

Ribonucleic acid extracts were isolated by cold phenol extraction procedure from lymphoid organs of mice immunized with allogeneic skin grafts. Cultivation of lymphocytes from normal mice with these RNA extracts in vitro led to the induction of specific immunological reactivity which was determined by microcytotoxicity assay. Pretreatment of the RNA extracts with DNase enhanced their ability to induce cytotoxicity, while pronase had no effect, and RNase completely inhibited the ability of extracts to sensitize lymphocytes. The results show that specific cell-mediated cytotoxicity can be induced in vitro in lymphocytes from normal animals by a transfer of "immune" RNA.

Animals↗
PubMed1978

Contribution to the taxonomy of haemolytic corynebacteria.

In an attempt to assess the taxonomic relationships among human (Corynebacterium haemolyticum), animal (Corynebacterium pyogenes bovis) haemolytic corynebacteria, typical corynebacteria (Corynebacterium diphteriae mitis, C. ovis, C. ulcerans) and group A and G streptococci, a number of biochemical parameters were established: the DNA content of G + C, the presence of the cytochrome system, composition of fatty acids in free lipids and production of carboxylic acids as end products of fermentation. It was found that according to the above criteria, streptococci differed significantly from the corynebacteria studied. In addition, it was possible to differentiate a subgroup of typically aerobic haemolytic corynebacteria (different from both human and animal corynebacteria), possessing a complete cytochrome system, producing propionic acid and having a different composition of fatty acids.

Carboxylic Acids↗
PubMed1977

The effect of shearing of XC DNA on its RSV transfecting activity.

XC DNA fragments having the average molecular weight of 10(7) daltons were obtained by hydrodynamic shearing followed by sucrose gradient centrifugation or BUdR treatment of XC cells used for DNA preparation. Such DNA molecules, even after long-term storage, were found to be active in transfection.

Animals↗