Int J Parasitol. 2002 Nov;32(12):1457-68.
Tetracycline treatment and sex-ratio distortion: a role for Wolbachia in the moulting of filarial nematodes?

Casiraghi M, McCall JW, Simoncini L, Kramer LH, Sacchi L, Genchi C, Werren JH, Bandi C.

Dipartimento di Patologia Animale, Universita di Milano, Milan, Italy.

Filarial nematodes harbour intracellular bacteria of the genus Wolbachia. These bacteria are thought to be beneficial to the host nematode. Indeed, tetracycline treatments reduce the population of Wolbachia in filarial worms and have detrimental effects on the nematode. Even though various antibiotic-curing experiments have been performed on filariae, the actual role of Wolbachia in the biology of these nematodes is not yet clear. To address this issue, we designed a first experiment on a model filaria (Brugia pahangi), maintained in the gerbil (Meriones unguiculatus). In this experiment, timing of tetracycline treatment was set on the basis of the larval stage of the nematode. This first experiment showed that 2 weeks of treatment started after the L(4)-L(5) moult of males, but before the moult of females, led to significant sex-ratio distortion of the nematodes. We thus hypothesised that tetracycline interferes with the moult in B. pahangi. To test this hypothesis, we designed a second experiment in which antibiotic treatments were started (1). before the moult of both sexes, (2). after the moult of males but before the moult of females, or (3). after the moult of both sexes. Treatment 1 determined a reduction of worm recovery with no sex bias. Treatment 2 led to a male-biased sex-ratio. Treatment 3 had no effect on either worm recovery or sex-ratio. These results thus support the hypothesis that tetracycline treatment interferes with the L(4)-L(5) moult of B. pahangi. The nematodes recovered from the treated and control animals were examined for the presence of Wolbachia using both immunohistochemistry and real-time PCR. In general, nematodes from treated animals showed a dramatic reduction in Wolbachia content. In one group, Wolbachia depletion, as observed at the end of the treatment, was followed by a rebound to 'normal' values 160 days later. Prospects for antifilarial therapy using Wolbachia-targeted tetracycline treatments should thus take into account the possibility of Wolbachia rebound.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12392911&dopt=Abstract antibiotics, tetracycline




J Gen Microbiol. 1981 Mar;123(Pt 1):187-91.
Molecular cloning in plasmid pBR322 giving altered expression of the tetracycline resistance gene.

Bastin M.

The two HindIII fragments of polyoma virus DNA were cloned in the HindIII site of plasmid pBR322, a site located in the RNA polymerase promoter involved in the expression of tetracycline resistance. Although insertion of foreign DNA into this site did not always result in the complete loss of tetracycline resistance, Escherichia coli K12 strain chi 1776 harbouring recombinant plasmids exhibited reduced growth properties in liquid culture with tetracycline and could easily be differentiated from bacteria transformed by non-recombinant plasmids. The formation of plasmid multimers increased the resistance to tetracycline at the level of the induction period, presumably as a result of a gene dosage effect.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6275002&dopt=Abstract antibiotics, tetracycline




Antibiotiki. 1978 May;23(5):433-6.
[Biological properties of sherry yeasts in the presence of antimicrobial preparations]

[Article in Russian]

Sidorchuk II.

The wine yeasts Cheres were not sensitive to high concentration (500 gamma/ml) of benzylpenicillin, streptomycin, tetracycline, oxytetracycline, chlortetracycline, morphocycline, erythromycin, oleandomycin, monomycin, neomycin, kanamycin, polymyxin, ampicillin, oxacillin, methicillin, ceporin, ristomycin, levomycetin, furadonin and furazolidone. In concentrations of 50 to 500 gamma-ml oleadomycin, chlortetracycline, oxytetracycline, kanamycin and ristomycin inhibited synthesis of the Cheres yeast biomass. Benzylpenicillin, polymyxin, neomycin and ampicillin in concentrations of 50 to 100 gamma/ml had a stimulating effect on the yeast biomass synthesis.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=655689&dopt=Abstract antibiotics, tetracycline




Antibiotiki. 1979 Feb;24(2):100-5.
[Antibiotic resistance of Shigella in different regions of the USSR]

[Article in Russian]

Solodovnikov IuP, Mamontova TN, Turchinskaia MV, Timina VP, Voskoboinikova MM.

Shigella were most sensitive to polymyxin ceporin, ampicillin, neomycin and furazolidone and resistant to chloramphenicol, tetracycline and streptomycin. Shigella resistant simultaneously to two or three drugs mainly to tetracycline + chloramphenicol, tetracycline + streptomycin and tetracycline + chloramphenicol + streptomycin were most frequent. The frequency of the Shigella strains carrying R-plasmids increased from 28 per cent in 1969--1970 to 72.6 per cent in 1977. The Shigella strains isolated during the dysentery outbreak in 1973--1977 carried the R-factor controlling resistance to tetracycline + chloramphenicol, tetracycline + chloramphenicol + streptomycin, tetracycline + chloramphenicol + streptomycin + neomycin. Interaction between separate biochemical types, colicinogenicity and drug resistance classes was found in the Shigella isolates. The data on the effect of antibiotic (tetracyclines) intensive use in stock-raising defining wide spread of the R-plasmids controlling resistance to these drugs were obtained.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=373617&dopt=Abstract antibiotics, tetracycline




Mol Cell Biol. 1995 Apr;15(4):1907-14.
Tetracycline-reversible silencing of eukaryotic promoters.

Deuschle U, Meyer WK, Thiesen HJ.

Basel Institute for Immunology, Switzerland.

A tetracycline-controlled transrepressor protein has been engineered to silence transcriptional activities of eukaryotic promoters that are stably integrated into the chromatin of human cells. By fusing the KRAB domain of human Kox1 to the Tet repressor derived from Tn10 of Escherichia coli, a tetracycline-controlled hybrid protein (TetR-KRAB) was generated and constitutively expressed in HeLa cells. The TetR-KRAB protein binds to tet operator (tetO) sequences in the absence but not in the presence of tetracycline. When TetR-KRAB bound to tetO sequences upstream of the immediate-early promoter-enhancer of human cytomegalovirus (CMV), the expression of a CMV-driven luciferase reporter construct (ptetO7-CMV-L) was repressed in transient transfection experiments. This silencing was found to operate on different promoters and from tetO sequences placed more than 3 kb from the transcriptional start site. We constructed a stable, doubly transfected cell line (TIS-10) carrying a chromosomally integrated ptetO7-CMV-L reporter construct and expressing the TetR-KRAB protein. Upon addition of tetracycline, luciferase expression was induced more than 50-fold above the baseline level, with half-maximal induction by 2 days. Furthermore, a protein of around 110 kDa was found to coimmunoprecipitate with the TetR-KRAB fusion protein. This protein might play a role as an adaptor protein mediating the silencing exerted by the TetR-KRAB protein. The TetR-KRAB silencing system should be useful as a genetic switch for regulating the expression of chromosomally integrated heterologous and endogenous genes present in mammalian genomes.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7891684&dopt=Abstract antibiotics, tetracycline




Res Vet Sci. 1994 May;56(3):277-83.
Simple continuous and simultaneous determination of tetracycline residues.

Tsai CE, Kondo F.

Department of Veterinary Public Health, Faculty of Agriculture, Miyazaki University, Japan.

A new continuous separation method was developed for the determination of five different tetracyclines (oxytetracycline, tetracycline, chlortetracycline, methacycline and doxycycline). A bioassay using minimum medium (MM) seeded with Bacillus subtilis ATCC 6633 was carried out for the detection, with simple extraction from the agar block of the clear inhibition zone on the MM produced by the mixed tetracyclines. The extract was subjected to continuous identification by high performance liquid chromatography using a mu-Bondapack C18 column. The tetracyclines were separated at ambient temperature using a mobile phase of 0.01 M oxalic acid: acetonitrile: N,N-dimethylformamide (74:18:8, v/v/v) at a flow rate of 1.0 ml min-1. A variable-wavelength detector set at 355 nm and recorder set at 4 mm min-1 were used for the detection. The entire mixture was resolved as five peaks with retention times ranging from 2.75 to 9.65 minutes. This continuous, simple and rapid method of detection, extraction and identification may be useful for routine laboratory testing of residual antimicrobial agents in food.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8073177&dopt=Abstract antibiotics, tetracycline




J Infect Dis. 1979 Apr;139(4):444-51.
Preparation of competent single-cell suspensions of Mycoplasma hominis tets and Mycoplasma salivarium tets for genetic transformation to tetracycline resistance by DNA extracted from Mycoplamsa hominis tetr.

Furness G, Cerone AM.

DNA extracted from Mycomplasma hominis (Sprott strain), resistant to 100 micrograms of tetracycline/ml transformed M. hominis strain H29 and Mycoplasma salivarium strain S9, which are sensitive to 2.5 and 5.0 micrograms of tetracycline/ml, respectively, to resistance. The transformants were selected on agar medium containing 10 micrograms of tetracycline/ml. Some transformants were resistant also to 20 micrograms of tetracycline/ml, a finding confirming that transformation occurred between homologous and heterologous species and that resistance is stepwise and controlled by several genetic loci. Medium containing 10 micrograms of tetracycline/ml was bacteriostatic. Prototype experiments employing mixtures of strains that were tetr and tets (tetracycline-resistant and tetracycline-sensitive, respectively) demonstrated that tetr mutants and transformants formed typical fried-egg colonies when mixtures containing not more than 10(9) mycoplasmas were spread on tetracycline agar plates. No mutants to tetracycline resistance were detected. Both M. hominis and M. salivarium were competent after treatment with MgCl2 and CaCl2, while Mycoplasma orale type 2 was inactivated. During DNA extraction different quantities of DNA formed insoluble precipitates with protein, thus preventing quantitative experiments.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=438545&dopt=Abstract antibiotics, tetracycline




J Mol Biol. 1983 Sep 25;169(3):707-21.
Control of expression of the Tn10-encoded tetracycline resistance genes. Equilibrium and kinetic investigation of the regulatory reactions.

Hillen W, Gatz C, Altschmied L, Schollmeier K, Meier I.

The transposon Tn10-encoded TET repressor controls the expression of tetracycline resistance as well as its own synthesis. The antibiotic tetracycline functions as an inducer for both genes, which are transcribed in divergent directions from a common start area. The interaction of the TET repressor with the regulatory sequence of the tetracycline resistance operon is investigated by equilibrium and kinetic methods. The wild-type control sequence contains two nearly identical operators separated by only ten base-pairs. A deletion mutant lacking one of the operators is constructed by controlled digestion with exonuclease Bal31. It serves to prove that the two TET operators are each occupied by a TET repressor dimer in the wild-type tet operon regulatory sequence. The association constants are approximately identical for both operators between 10(12) and 10(13) M-1 as derived from kinetic data. The half-life of the TET repressor--tet operator complex is 12 minutes when competed with tet operator DNA and two minutes when competed with the inducer tetracycline. The dissociation of the repressor--operator complex has no apparent activation enthalpy but has an activation entropy of -320 J/mol K, indicating the involvement of solvent or counterion condensation. The dissociation rate constant of the tetracycline--TET repressor complex depends strongly on temperature. The activation enthalpy is 160 kJ/mol, indicating extremely strong binding of the drug. This result is discussed with respect to the necessary sensitivity of a regulated resistance gene. The native structure of the TET repressor is a dimer, as demonstrated by molecular exclusion chromatography. The elution behavior of the TET repressor--tetracycline complex indicates clearly that the repressor--inducer complex remains a dimer. The results are discussed with respect to the regulatory functions of the components.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6313933&dopt=Abstract antibiotics, tetracycline