Plasmid. 1992 Nov;28(3):213-24.
Tetracycline enhances Tn916-mediated conjugal transfer.

Showsh SA, Andrews RE Jr.

Department of Microbiology, Immunology, and Preventive Medicine Iowa State University, Ames 50011.

Pregrowth of the donor on medium containing tetracycline increased conjugative transposition of Tn916 and the transposon-dependent mobilization of pC194 19- to 119-fold in matings between Bacillus subtilis and Bacillus thuringiensis subsp. israelensis. Tn916 and pC194 transferred independently under these conditions. When Enterococcus faecalis was the donor and B. thuringiensis subsp. israelensis the recipient, pregrowth in tetracycline increased the conjugative transposition frequency by approximately 15-fold. Tetracycline-enhanced conjugation appeared during matings as short as 3 h in length. Pregrowth in tetracycline did not enhance conjugation in Bacillus sphaericus x B. thuringiensis subsp. israelensis or B. thuringiensis subsp. israelensis x B. subtilis matings. Incorporation of tetracycline into the mating medium, at concentrations that did not inhibit growth of the B. thuringiensis subsp. israelensis recipient, resulted in conjugation frequencies similar to those obtained by pregrowth of the B. subtilis donors in antibiotic-containing medium. The data suggest stimulation of donor function by tetracycline.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1334267&dopt=Abstract antibiotics, tetracycline




Plant Physiol. 2001 Apr;125(4):1548-53.
Characterization of a tobacco Bright Yellow 2 cell line expressing the tetracycline repressor at a high level for strict regulation of transgene expression.

David KM, Perrot-Rechenmann C.

Institut des Sciences Vegetales, Centre National de la Recherche Scientifique, Unite Propre de Recherche 040, Auxin Perception and Transport Laboratory, Avenue de la Terrasse, 91198 Gif-sur-Yvette cedex, France.

Manipulating the expression of a transgene in transient and stable transformed cells is a requirement for many functional analyses. We have investigated the use of the tetracycline-dependent gene expression system developed by Gatz et al. (1992) in tobacco (Nicotiana tabacum L. cv Bright Yellow 2 [BY2]) cells, the most widely used plant cell culture. We have selected a BY2 cell line, named BY2-tetracycline repressor (tetR) 17, which expresses the tetR at a high level, and have evaluated the capacity of this cell line to suppress the expression of a green fluorescent protein reporter gene under the control of the "Triple-Op" promoter in the absence of tetracycline in a large number of independent transformants. The ability to induce the expression of green fluorescent protein after treatment by anhydrotetracycline in the same transformants was also analyzed. BY2-tetR17 cells were demonstrated to be excellent recipient cells for recovery of clonal cell lines with a highly controlled regulation of the introduced transgene.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11299335&dopt=Abstract antibiotics, tetracycline




Calcif Tissue Int. 1985 Jan;37(1):32-5.
Relationship between toluidine blue-stained calcification fronts and tetracycline-labeled surfaces in normal human iliac crest biopsies.

Compston JE, Vedi S, Webb A.

The relationship between toluidine blue-stained calcification fronts and tetracycline labeling was examined in iliac crest biopsies from 56 normal subjects aged 19-80 years, all of whom had received double tetracycline labeling. Sections were quantitated using an eye-piece graticule and all values were expressed as a percentage of osteoid surface. Values for double plus single tetracycline-labeled surfaces were lower than those obtained for toluidine blue-stained calcification fronts in 66% of subjects, although the difference between the two measurements was not statistically significant. Values obtained for calcification fronts demonstrated by toluidine blue staining were significantly greater than those obtained for single, double, and double plus half single tetracycline-labeled surfaces. No significant correlation could be demonstrated between toluidine blue-stained calcification and tetracycline-labeled surfaces. In conclusion, the fraction of osteoid bearing a tetracycline label differed from that showing a toluidine blue-stained calcification front and no correlation could be demonstrated between the two measurements. These differences may arise from methodological problems associated with their demonstration and identification; alternatively their lack of similarity might reflect uptake of stain and tetracycline at different sites within the calcification front. Which of the two parameters most accurately represents the active mineralizing surface is unknown.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2581681&dopt=Abstract antibiotics, tetracycline




Antibiot Khimioter. 1994 Nov;39(11):3-9.
[Metabolic transformation of antibiotics of the tetracycline series in peroxidase reactions]

[Article in Russian]

Petrenko IuM, Titov VIu, Vladimirov IuA.

In was shown calorimetrically that in the presence of horse radish peroxidase tetracyclines induced degradation of hydrogen peroxide. Under such conditions changes in the tetracycline optical properties were detected photometrically. It was concluded that tetracyclines were metabolized in the peroxidase reactions catalyzed by horse radish peroxidase as their substrates. The tetracycline peroxidase oxidation was catalyzed not only by horse radish peroxidase but also by methemoglobin possessing the peroxidase activity. In the experiments with ascorbate there were detected characteristic peculiarities of the tetracycline peroxidase oxidation catalyzed by both horse radish peroxidase and methemoglobin. These peculiarities made it possible to classify the tetracyclines as the substrates of the peroxidase reaction belonging to the oxidogenic group. The fact that tetracyclines can be metabolized in peroxidase reactions is discussed in regard to its possible influence on their mechanism of antibacterial action and the development of tetracycline resistance.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7733773&dopt=Abstract antibiotics, tetracycline




J Diarrhoeal Dis Res. 1994 Dec;12(4):270-3.
Antimicrobial susceptibility and plasmid analysis of Campylobacter jejuni isolated from diarrhoeal patients and healthy chickens in northern India.

Prasad KN, Mathur SK, Dhole TN, Ayyagari A.

Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.

Seventy-five strains of Campylobacter jejuni isolated from humans with diarrhoea (45 strains) and healthy chickens (30 strains) were tested for their susceptibility to different antimicrobial agents: ampicillin, tetracycline, erythromycin, gentamicin, kanamycin, furazolidine and quinolones (nalidixic acid, norfloxacin, ciprofloxacin). The frequencies of resistance to ampicillin and tetracycline were 16 and 9.3% respectively. Two strains (2.7%) exhibited resistance to quinolones as mentioned. One strain (1.3%) was resistant to erythromycin, and both ampicillin plus tetracycline. One strain (1.3%) exhibited resistance to multi-drugs (ampicillin, tetracycline and erythromycin). Resistance to ampicillin was higher in human strain (22.2%) compared to chickens (6.7%). On the contrary, the frequency of resistance to tetracycline was higher in chicken strains (13.3%) than in human (6.7%). All the ampicillin-resistant strains produced beta-lactamase. None of the ampicillin, erythromycin and quinolone-resistant strains contained any plasmid but all the tetracycline-resistant strains contained 23 kilobase (kb) plasmid which could be transferred to an ampicillin-resistant C. jejuni strain. This study thus shows that ampicillin and tetracycline resistance in C. jejuni are common in northern India. Ampicillin resistance is chromosomally determined but tetracycline resistance is mediated through 23 kb plasmid.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7751568&dopt=Abstract antibiotics, tetracycline




Eur J Biochem. 2000 Jan;267(2):527-34.
Permeation of tetracyclines through membranes of liposomes and Escherichia coli.

Sigler A, Schubert P, Hillen W, Niederweis M.

Lehrstuhl fur Mikrobiologie, Friedrich-Alexander-Universitat Erlangen-Nurnberg, Germany.

Uptake of tetracycline (tc), 2-tetracyclinonitrile (CN-tc), and 9-(N, N-dimethylglycylamido)-6-demethyl-6-deoxytetracycline (DMG-DMDOT) by liposomes containing Tet repressor (TetR) and by Escherichia coli cells overexpressing TetR was examined. TetR specifically binds to tetracyclines, enhances their fluorescence and thereby allows selective detection of tetracyclines that have crossed the membranes. Analysis of the diffusion of tc and DMG-DMDOT into liposomes yielded permeation coefficients of (2.4 +/- 0.6) x 10-9 cm.s-1 and (3.3 +/- 0.8) x 10-9 cm.s-1, respectively. Similar coefficients were obtained for uptake of these tetracyclines by E. coli, indicating that diffusion through the cytoplasmic membrane is the rate-limiting step. The permeation coefficients translate into half-equilibration times of approximately 35 +/- 15 min and explain how efflux pumps can mediate resistance against tetracyclines. Furthermore, diffusion of CN-tc into liposomes was at least 400-fold slower than that of tc, indicating that the carboxamide group at position C2 is required for efficient permeation of tc through lipid membranes and thereby explaining the lack of antibiotic activity of CN-tc.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10632722&dopt=Abstract antibiotics, tetracycline

dna.bio.warwick.ac.uk

A diverse collection of methicillin-resistant Staphylococcus aureus (MRSA) isolates resistant to tetracycline was screened by PCR for the presence of the resistance determinants tetK, tetL, tetM or tetO. Twenty-four of 66 isolates had tetM alone, 21 had tetK alone and 21 had both tetK and tetM (tetKM). All isolates were tetL- and tetO-negative. MICs of tetracycline, doxycycline and minocycline were evaluated for all isolates with or without preincubation in the presence of subinhibitory concentrations of tetracycline or minocycline. All isolates with one or more tetracycline resistance determinants were resistant to tetracycline 8 mg/L without induction of resistance. Some MRSA isolates of each of these three genotypes showed an unexpected lack of resistance to tetracyclines when the disc diffusion or agar dilution method was applied to uninduced cells. Resistance to tetracycline and doxycycline was greater (two- to four-fold) in tetK cells preincubated with tetracycline (tetK MRSA isolates were susceptible to minocycline </=0.25 mg/L under all conditions tested). For isolates with tetM alone, preincubation with tetracycline or minocycline gave up to a four-fold increase in the level of resistance to doxycycline and minocycline. Induction of doxycycline and minocycline resistance was clearly observed for tetKM isolates when cells were preincubated with minocycline. This study suggests that, despite the results of susceptibility testing, all tetracycline-resistant S. aureus isolates should be treated as resistant to doxycycline, and all tetM-positive isolates should be treated as resistant to all tetracyclines. A double disc diffusion method has been developed to identify inducible resistance to minocycline and to distinguish between tetK, tetM and tetKM isolates.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10837427&dopt=Abstract antibiotics, tetracycline




J Anat. 1975 Feb;119(1):49-59.
On the relationship between tetracycline and the incremental lines in dentine.

Kawasaki K, Fearnhead RW.

Ground and decalcified sections of human, goat and pig teeth were examined using polarized and ultraviolet fluorescence microscopy, microradiography and electron microscopy. The experimental animals were given doses of tetracycline within the range 3-150 mg/kg. After the low doses there was no evidence of any disturbance of mineralization or of structural organization in either the goat or the pig. After the higher doses, however, the tetracycline lines usually corresponded with a disturbance of structural organization and often with a disturbance of mineralization as well. In the human cases, the tetracycline lines sometimes corresponded with a disturbance of mineralization or of structural organization. However, our evidence suggests that the disturbances in the structure or mineralization of the dentine in the human subjects were not caused by the tetracycline. It was concluded that, provided the dose is kept low (3-31 mg/kg) tetracycline can be used as a reliable non-toxic marker in growth studies and is also used in the study of mineral deposition.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1133088&dopt=Abstract antibiotics, tetracycline