Detection of specific RNA sequences in yeast by in situ colony hybridization

Recently a convenient method for detection of specific RNA sequences in bacteria has been developed but the original protocol was inapplicable to microorganisms with a rigid cell wall. Here we report a modification of the RNA colony hybridization for use with yeast. The modified method includes the following consecutive procedures: a) treatment of the yeast colonies on the membrane filter with 10% SDS at 65% C for 30 min; b) treatment of the same filter with 3 x SSC, 10% formaldehyde at 65 degrees C for 30 min; c) hybridization with 32P-labelled oligonucleotide (or DNA) specific for the RNA sequence of interest. The intensity of the radioactive signals thus obtained is comparable with that of the E. coli colonies.

Amplification of bacterial plasmids without blocking protein biosynthesis

The effect of amino acids (presence or absence from the growth media) and metal ions on the replication of Escherichia coli plasmids in rel A+ strains was studied. It was found that: (i) The absence of one amino acid from the growth media had no effect on the plasmid copy number in prototrophic E. coli strains: (ii) The presence of only one amino acid in artificial media free of amino acids had a negligible effect on the plasmid copy number for the amino acids Ala, Arg, Glu, His, Leu, Phe, Thr, Trp, and Tyr: (iii) The combination of Met and Thr caused a rise in pBR322 plasmid copy number up to 90-100 plasmid copies per cell: (iv) The Fe3+ concentration had an amplification effect on E. coli plasmids. The pBR322 plasmid copy number for media free of amino acids and supplemented with 0.2-0.4 mM FeCl3 was 60-80 plasmid copies per cell: (v) The combination of Fe3+ with certain amino acids (Ala, Arg, Glu, Leu, Thr, and Trp) leads to a dramatic increase in the plasmid copy number reaching 180-270 plasmid copies per cell for the plasmid pBR322 and 20-24 for the plasmid pR100.

Expression of repetitive human calcitonin genes in Escherichia coli

In order to stabilize recombinant human calcitonin (rhCT) against Escherichia coli proteases a series of concatemeric hCT genes with varying degrees of repetition were synthesized and expressed in E. coli under the control of a constitutive synthetic phage promoter. The series of expression vectors thus constructed was used as a model to study the effect of gene repetition on the efficiency of expression (both transcription and translation), stability of mRNA, proteolytic stability of recombinant protein, genetic stability of expression plasmids, etc. The oligomerization of the hCT gene resulted in stabilization of the mRNA increasing its half-life from 60-70 s (as in the hCT monomer, dimer, and trimer genes) to 100-120 s (for the hCT tetramer gene). This effect held true as well for the proteins coded by the corresponding repetitive hCT genes. The genetic stability (segregation and recombination) of the expression plasmids containing hCT oligomeric genes also depended on the number of hCT gene repeats. The expression plasmid containing the hCT tetramer gene segregated from one of the best producers of rhCT (E. coli LE392) up to 100% after 100 cell generations in nonselective media (free of antibiotics). One of the plasmids most sensitive to recombination events was that containing the hCT pentamer gene. The series of expression plasmids bearing hCT oligomeric genes was used for transformation of various E. coli strains in order to find the optimal host for production of rhCT. The highest yield (44-100 mg rhCT per 1 liter of bacterial culture) was obtained with the strains LE392, JM107, and DH1.

Expression of synthetic calcitonin genes in plasmid vectors containing tandemly repeated non-overlapping ribosome binding sites

1. Expression plasmids containing non-overlapping tandemly repeated ribosome binding sites (RBS) were constructed in order to stabilize mRNA and enhance translation. 2. Two synthetic genes (human calcitonin tetramer gene and a fusion gene human gamma-interferon-human calcitonin) were cloned in these vectors and the effect of multiplicity of Shine-Dalgarno (S/D) sequence on heterologous gene expression was studied. 3. It was found that duplication and triplication of RBS had no effect on the stability of mRNA but led to a strong decrease in the level of recombinant protein and mRNA in the cell. 4. Plasmids bearing four times repeated S/D sequences gave longer-lived mRNAs and maintained a level of protein and mRNA very close to the values obtained with a single S/D containing plasmids.

Constitutive expression of a native human interferon-alpha 1 gene in Escherichia coli

1. A plasmid for constitutive expression of the human interferon-alpha 1 (hIFN-alpha 1) gene in Escherichia coli is constructed on the basis of the cloning plasmid pBR322 using a strong synthetic promoter, synthetic ribosome binding site and a native hIFN-alpha 1 gene excised from a chromosomal clone. 2. The yield of recombinant hIFN-alpha 1 from E. coli LE392 cells transformed with the expression plasmid pJP1R9-hIFN-alpha 1 is evaluated to be 2-6 x 10(7) U/l bacterial culture for metabolic shaker and 6-8 x 10(7) U/l for fermentor.

[Working model for experimental stomatoscopy]

The authors, for the first time in our country, created working conditions for stomatoscopy on materials and trial-copies to be studied in advance, approaching in type and form to the oral cavity mucosa in norm and pathology. The magnifying possibilities of stomatoscope in observation of working trial-copies are clearly illustrated. Stomatoscopy is recommended as a diagnostic method in pathology of oral cavity mucosa after acquiring the necessary habits and skill, based on the experimental stomatoscopy described.

A conditional high-copy-number plasmid derivative of pBR322

A spontaneous high-copy-number plasmid derivative of plasmid pBR322 was isolated. This plasmid bears two point mutations adjacent to the unpaired region in the stem of loop II of RNA I and expresses its high-copy-number phenotype only when the harboring cells grow on solid support (L-agar).

What does the homology between E. coli tRNAs and RNAs controlling ColE1 plasmid replication mean?

Nucleotide sequences of E. coli tRNAs and RNA I or RNA II (controlling replication of ColE1 plasmids) were compared using the computer. The homology between some of these molecules is over 60%. The distribution of homologous nucleotides among the functional elements (stems and loops) of either RNA I or RNA II and the tRNAs molecules was studied. It was found that the homologous domains are located mainly in the loop regions of RNA I or RNA II. A consensus sequence, the nonanucleotide AGUUGGUAG, was discovered in loop II of RNA I and in the dihydrouridylic loop of tRNAs showing homology with RNA I. Based on this observation, a hypothesis was drawn for a possible role of the tRNAs in the regulation of plasmid DNA replication.

Inclusion bodies in recombinant E. coli producing human calcitonin tetramer, as visualized by immuno-gold electron microscopy

Inclusion bodies are described in recombinant E. coli cells harboring plasmid for the expression of a synthetic gene coding for human calcitonin tetramer. The inclusion bodies are visualized by electron microscopy and the protein is identified by immuno-gold technique, using antibodies against synthetic human calcitonin. The diameter of the inclusion bodies is 1 micron on the average.

Chemical synthesis and expression in E. coli of a human Val8-calcitonin gene by fusion to a synthetic human interferon-gamma gene

A gene coding for human Val8-calcitonin (Val8-hCT) was synthesized by the solid-phase phosphite approach and fused to a synthetic human immune interferon-gamma (IFN-gamma) gene. The IFN gene was previously shown to be expressed at a very high level in E. coli [(1986) Gene, in press] due to the control of a strong synthetic promoter and strong ribosome binding site. The cells harboring the fused gene produced 100-150 micrograms per l of bacterial suspension of immunoreactive calcitonin in the form of hybrid IFN-gamma-Val8-hCT protein consisting of 140 amino acids. The Val8-hCT can be released from this protein by CNBr treatment.

Chemical synthesis and expression of the human calcitonin gene

A gene coding for the peptide hormone, human calcitonin (hCT), has been constructed and expressed in bacteria using a prokaryotic vector containing the strong T5P25 promoter and a strong ribosome-binding site. The bacterial hCT is different from the natural hCT by having an additional Met residue at the N terminus and a non-amidated C terminus. Despite these differences, the bacterial hCT is biologically active in rat cells. The results are important for future structure-function relationship studies using mutants constructed by genetic engineering.

Excitation-contraction latency in the muscles of children and adults

Excitation-contraction latency in the fast flexor carpi ulnaris and in the slow triceps surae muscles was studied in healthy children aged one month, 10 months and three years, and in adults. The tests were carried out during isometric twitch following supramaximal indirect stimulation. Excitation-contraction latency was found to increase with age in both the fast and slow muscles. The latency is longer for the slow than the fast muscle. A positive correlation was found in the children between excitation-contraction latency and contraction time.

RNA colony hybridization method

A method for rapid screening of specific RNA sequences in recombinant colonies by hybridization in situ is presented. The method includes two consecutive steps of lytic treatment of the nitrocellulose-filter-supported colonies (10% sodium dodecyl sulfate and 3 X SSC at 65 degrees C) and hybridization with 32P-labelled specific oligodeoxynucleotides.

Isolation of lambda phage DNA by hydroxylapatite chromatography

A simple and rapid (1 day) method for preparation of lambda phage DNA was proposed. The method included two main steps: (a) growth and lysis of bacteria containing lambda phage and (b) purification of lambda phage DNA by hydroxylapatite chromatography. The phage DNA prepared by this method was intact and free of RNA, proteins, and bacterial DNA.

[Respiratory diseases in sheep due to Mycoplasma ovipneumoniae]

Mycoplasma ovipneumoniae was isolated from sheep and lambs affected with a respiratory disease. It was established that the pneumonic disease caused by this organism was a severe one, with high mortality rate in young lambs. Adult sheep and older lambs remained chronically affected. Susceptibility varied, depending on the breed of the animals, some imported animals running a more severe course of the disease than the local ones. The disease was artificially induced in lambs at the joint infection with M. ovipneumoniae and P. haemolytica. The morphologic changes in the lungs consisted in a prevailing proliferation of the septal cells and polynuclear cells in the alveoli, an interseptal histiocyte proliferation, and a serous leukocyte infiltration.

Spin-labelling of DNA with hydrazine mustard spin label (HMSL)

1. The hydrazine mustard spin label (HMSL), recently synthesized in our laboratory (Raikova, 1977) was used for spin-labelling of DNA. 2. It alkylates both double- and single-stranded DNAs. 3. The reaction of HMSL with DNA was studied with respect to the kinetics of alkylation, dependence on salt concentration and base specificity. 4. It was found that HMSL is a base-specific reagent, alkylating preferentially guanine. According to their ability to bind HMSL, the four deoxyribonucleotides are ordered in the following way: G greater than A greater than C greater than T. 5. The EPR spectra obtained strongly depended on the secondary structure of the spin-labelled DNA: unlike the immobilized spectra of the double-stranded DNAs (2AZZ = 44.8G), the EPR spectra of single-stranded DNAs were non-immobilized (2AZZ = 32.8 G). 6. When sheared double-stranded DNA was spin-labelled, the parameters of the EPR spectrum depended also on the GC content of DNA.

[Biorhythm changes in DNA synthesis in hepatocytes exposed to organophosphates and strontium-89]

The authors irradiated albino rats with I microc/gr strontium89 with previously modelled liver injury by FOS (Agria 1050). A temporary inhibition of the methodical activity was established as well as aberrant mitoses and strongly manifested polyploidity of the hepatic cells. Those phenomena faded quickly (within 8 days), with the exception of polyploidity, which as a sign of physiological regeneration the authors admit to be adaptive reaction directed to the restoration of the functional level of the liver on account of the hepatocytes preserved. Prior to the onset of tissue regeneration, the cellular one should be terminated, due to which, the mytotic activity was highly inhibited on the 3rd day of the irradiation, the DNA-synthesis cycle being lengthened and mainly on account of tgi, i.e. during the reparative biosynthesis the cell is incapable/of developing in the mitotic phase. After the presynthetic period is over the hepatocytes rapidly overcome the inhibition, tgi is considerably shortened and from presynthesis they almost immediately enter the period of mitosis. That requires an additional protein synthesis, manifested by the changes in serum protein. S and G1 proved to be most sensitive to DNA-synthesis blocking. The presynthetic period is essentially lengthened due to lesions of the cellular structures, synthesizing substances, necessary for entering S - i.e. the hepatocytes pass T, equal to the inhibition between G1 and S, its duration being proportional to the degree of the lesion of the organ.