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PubMed1999

A new chloramphenicol and florfenicol resistance gene flanked by two integron structures in Salmonella typhimurium DT104.

A new chloramphenicol resistance gene from Salmonella typhimurium DT104, designated floR, also conferring resistance to florfenicol, was characterized. Sequence analysis of the deduced FloR protein suggested that it belongs to the 12-TMS (transmembrane segments) multidrug efflux pumps family. The floR gene, and the downstream sequenced tetR and tetA tetracycline resistance genes, were surrounded by two class 1 integrons. The first one contained the resistance gene aadA2 and a deleted sulI resistance gene. The second one contained the beta-lactamase gene pse1 and a complete sulI gene. Thus, the floR gene is included in a multiresistance locus of at least 12.5 kb. Its particular organization and chromosomal location could be involved in the antibioresistance pattern stability of the DT104 Salmonella typhimurium strains.

Anti-Bacterial Agents↗
PubMedDate not supplied

Influence of vitamins and iron on plasma fluoride levels in rats.

Thirty female Sprague-Dawley rats (250 +/- 10 g) were divided randomly into five equal groups. After overnight fasting, a silastic catheter was placed in the jugular vein of each rat. Each group was intragastrically administered 0.25 mg F/250 g rat weight in 1 ml of one of the following forms of fluoride supplements: Pediaflor (Abbott/Ross, Columbus, OH), Tri-Vi-Flor, Tri-Vi-Flor + iron; Poly-Vi-Flor or Poly-Vi-Flor + iron (Mead Johnson Nutritionals, Bristol-Myers Squibb Co., Evansville, IN). Timed blood samples were collected and plasma fluoride concentration was determined using the microdiffusion method. The presence of iron and vitamins affect the bioavailability of fluoride as measured by the area under the time-plasma fluoride concentration curve.

Animals↗
PubMed1988

[Hybridization of homothallic wine yeasts with heterothallic strains].

Most of the yeast strains of industrial interest are homothallic, which makes genetic analysis as well as improvement of their desirable properties extremely difficult. In this work, all the wine yeasts analyzed, except for two "flor" yeasts which were able to generate heterothallic meiotic products, were homozygous for the HO allele of homothallism. The genetic analysis of one of the "flor" yeast spores, which was heterothallic, indicated that the strain carried an HO allele of homothallism and that its heterothallic behaviour was due to a genetic constitution HML MAT HMR HO. This HO allele of the "flor" yeast behaved differently from other HO alleles present in the wine yeasts. It gave rise to a very retarded homothallism, with formation of selfzygotes which presented an abnormal morphology. These zygotes generated selfdiploids whose ability to sporulate was very inefficient. The lag in the expression of the homothallism allowed the isolation of hybrids between meiotic products of the "flor" yeasts and heterothallic laboratory strains with a frequency of 10(-1), as compared to that of the meiotic products of other wine yeasts, which was of 10(-4) to 10(-6). This result indicates that, among other factors which could influence the frequency of hybrid formation, the lag in the expression of homothallism could be the most important one. The use of heterothallic laboratory strains of mating type as opposed to a strain of alpha mating type, as well as the frequency of viable nucleus in the hybrid zygote after conjugation, also seemed to influence the success of hybrid formation between laboratory strains and the wine homothallic strains used.

Genes, Fungal↗
PubMed2000

Phenolic compounds and browning in sherry wines subjected to oxidative and biological aging.

The composition in hydroxybenzoic and hydroxycinnamic acids, hydroxycinnamic esters, tyrosol, syringaldehyde, and flavan-3-ol derivatives of three different types of sherry wine obtained by aging of the same starting wine under different conditions was studied. So-called "fino" wine was obtained by biological aging under flor yeasts, "oloroso" wine by oxidative aging, and "amontillado" wine by a first stage of biological aging followed by a second oxidative step. On the basis of the results, the wines subjected to oxidative aging exhibited higher phenol contents, in addition to scarcely polar compounds absorbing at 420 nm that were absent in the wines obtained by biological aging. Taking into account that flavan-3-ol derivatives play an important role in wine browning, a model catechin solution was inoculated with flor yeast which, contrary to the findings of other authors in the absence of yeasts, formed no colored compounds. This different behavior may account for the resistance to browning of pale sherry wines in the presence of flor yeasts.

Food Handling↗
PubMed2004

Antibiotic resistance genes, integrons and multiple antibiotic resistance in thirty-five serotypes of Salmonella enterica isolated from humans and animals in the UK.

OBJECTIVES: To examine 397 strains of Salmonella enterica of human and animal origin comprising 35 serotypes for the presence of aadB, aphAI-IAB, aadA1, aadA2, bla(Carb(2)) or pse1, bla(Tem), cat1, cat2, dhfr1, floR, strA, sul1, sul2, tetA(A), tetA(B) and tetA(G) genes, the presence of class 1 integrons and the relationship of resistance genes to integrons and antibiotic resistance. RESULTS: Some strains were resistant to ampicillin (91), chloramphenicol (85), gentamicin (2), kanamycin (14), spectinomycin (81), streptomycin (119), sulfadiazine (127), tetracycline (108) and trimethoprim (45); 219 strains were susceptible to all antibiotics. bla(Carb(2)), floR and tetA(G) genes were found in S. Typhimurium isolates and one strain of S. Emek only. Class 1 integrons were found in S. Emek, Haifa, Heidelberg, Mbandaka, Newport, Ohio, Stanley, Virchow and in Typhimurium, mainly phage types DT104 and U302. These strains were generally multi-resistant to up to seven antibiotics. Resistance to between three and six antibiotics was also associated with class 1 integron-negative strains of S. Binza, Dublin, Enteritidis, Hadar, Manhattan, Mbandaka, Montevideo, Newport, Typhimurium DT193 and Virchow. CONCLUSION: The results illustrate specificity of some resistance genes to S. Typhimurium or non- S. Typhimurium serotypes and the involvement of both class 1 integron and non-class 1 integron associated multi-resistance in several serotypes. These data also indicate that the bla(Carb(2)), floR and tetA(G) genes reported in the SG1 region of S. Typhimurium DT104, U302 and some other serotypes are still predominantly limited to S. Typhimurium strains.

Animals↗
PubMed2005

Plasmid-borne florfenicol resistance in Pasteurella multocida.

OBJECTIVES: A florfenicol-resistant Pasteurella multocida isolate from a calf was investigated for the genetic basis of florfenicol resistance and the location of the resistance gene. METHODS: The P. multocida isolate 381 was investigated for its in vitro susceptibility to antimicrobial agents and its plasmid content. A 10.8 kb florfenicol-chloramphenicol resistance plasmid, designated pCCK381, was identified by transformation into Escherichia coli. The plasmid was mapped with restriction endonucleases, cloned and sequenced completely. RESULTS: Of the antimicrobials tested, plasmid pCCK381 conferred resistance only to chloramphenicol and florfenicol. It showed extended similarity to the 5.1 kb plasmid pDN1 from Dichelobacter nodosus in the part carrying the mobilization and replication genes. An adjacent 3.2 kb segment was highly homologous to the florfenicol resistance gene region of plasmid pMBSF1 from E. coli. In pCCK381, combined resistance to chloramphenicol and florfenicol was based on the presence of a floR gene that showed 97.2-99.7% identity to so far known floR genes. CONCLUSIONS: The results of this study showed that a plasmid-borne floR gene was responsible for chloramphenicol and florfenicol resistance in the bovine respiratory tract pathogen P. multocida. This is, to the best of our knowledge, the first report of a florfenicol resistance gene in a target bacterium.

Animals↗
PubMed2006

Plasmid-mediated florfenicol resistance in Pasteurella trehalosi.

OBJECTIVES: A florfenicol-resistant Pasteurella trehalosi isolate from a calf was investigated for the presence and the location of the gene floR. METHODS: The P. trehalosi isolate 13698 was investigated for its in vitro susceptibility to antimicrobial agents and its plasmid content. A 14.9 kb plasmid, designated pCCK13698, was identified by transformation into Pasteurella multocida to mediate resistance to florfenicol, chloramphenicol and sulphonamides. The plasmid was sequenced completely and analysed for its structure and organization. RESULTS: Plasmid pCCK13698 exhibited extended similarity to plasmid pHS-Rec from Haemophilus parasuis including the region carrying the parA, repB, rec and int genes. Moreover, it revealed similarities to plasmid RSF1010 in the parts covering the mobC and repA-repC genes and to plasmid pMVSCS1 in the parts covering the sul2-catA3-strA gene cluster. Moreover, the floR gene area corresponded to that of transposon TnfloR. In addition, two complete insertion sequences were detected that were highly similar to IS1593 from Mannheimia haemolytica and IS26 from Enterobacteriaceae. Several potential recombination sites were identified that might explain the development of plasmid pCCK13698 by recombination events. CONCLUSIONS: The results of this study showed that in the bovine pathogen P. trehalosi, floR-mediated resistance to chloramphenicol and florfenicol was associated with a plasmid, which also carried functionally active genes for resistance to sulphonamides (sul2) and chloramphenicol (catA3). This is to the best of our knowledge the first report of resistance genes in P. trehalosi and only the second report of the presence of a florfenicol-resistance gene in target bacteria of the family Pasteurellaceae.

Animals↗
PubMed2006

Genetic characterization of strains of Saccharomycescerevisiae responsible for 'refermentation' in Botrytis-affected wines.

AIMS: Saccharomyces cerevisiae is responsible for alcoholic fermentation of wines. However, some strains can also spoil sweet Botrytis-affected wines. Three 'refermentation' strains were isolated during maturation. Characterization of those strains in regards to their fingerprint, rDNA sequence and resistance to SO2, which constituted the main source of stress in Botrytis-affected wines, was carried out. METHODS AND RESULTS: Refermentation strains could be clearly discriminated by interdelta fingerprinting. However, they exhibited close relationships by karyotyping. A part of RDN1 locus sequence was examined by using PCR-RFLP and PCR-DGGE. The resistance of refermentation strains to SO2 was performed by using real time quantitative PCR focusing on SSU1 gene. CONCLUSIONS: Results suggested that refermentation strains were heterozygote in 26S rDNA and their ITS1-5.8S rDNA-ITS2 region sequence revealed relationships with 'flor' strains. As described in the literature for flor strain, two out of three refermentation strains constitutively developed a higher level of SSU1 expression than the reference strains, improving their putative tolerance to SO2. Therefore, refermentation strains of S. cerevisiae had developed many strategies to survive during maturing sweet wines. SIGNIFICANCE AND IMPACT OF THE STUDY: Singularities in rDNA sequence and SSU1 overexpression revealed a natural adaptation. Moreover, genomic relationship between flor and refermentation strains suggested that stress sources could induced selection of survivor strains.

Acetaldehyde↗
PubMed2001

Standard and C-banded meiotic karyotypes of Psylloidea (Sternorrhyncha, Homoptera, Insecta).

Meiotic karyotypes were studied in males of Craspedolepta sonchi (Foerster, 1848), Diaphorina chobauti Puton, 1898, D. lamproptera Burckhardt, 1981, Psylla hartigii Flor, 1861, Cacopsylla palmeni (Loew, 1878), C. hippophaes (Foerster, 1848), C. melanoneura (Foerster, 1868), C. pyricola (Foerster 1848), C. moscovita (Andrianova, 1848), Bactericera salicivora (Reuter, 1876), Trioza abdominalis Flor, 1861, T. lauri = Lauritrioza alacris (Flor, 1861). Karyotypes were 2n = 25 (24 + XO) in all species except B. salicivora with 2n = 26 (24 + neo-XY). Testes consisted of two follicles each in all species but P. hartigii with four-follicular testes in males. The discussion covers the problems of chromosome numbers, sex-determining chromosome systems, B-chromosomes, patterns of C-banding, testis structure, and spermatid development in Psylloidea.

Animals↗
PubMed2003

Response to acetaldehyde stress in the yeast Saccharomyces cerevisiae involves a strain-dependent regulation of several ALD genes and is mediated by the general stress response pathway.

One of the stress conditions that yeast may encounter is the presence of acetaldehyde. In a previous study we identified that, in response to this stress, several HSP genes are induced that are also involved in the response to other forms of stress. Aldehyde dehydrogenases (ALDH) play an important role in yeast acetaldehyde metabolism (e.g. when cells are growing in ethanol). In this work we analyse the expression of the genes encoding these enzymes (ALD) and also the corresponding enzymatic activities under several growth conditions. We investigate three kinds of yeast strains: laboratory strains, strains involved in the alcoholic fermentation stage of wine production and flor yeasts (responsible for the biological ageing of sherry wines). The latter are very important to consider because they grow in media containing high ethanol concentrations, and produce important amounts of acetaldehyde. Under several growth conditions, further addition of acetaldehyde or ethanol in flor yeasts induced the expression of some ALD genes and led to an increase in ALDH activity. This result is consistent with their need to obtain energy from ethanol during biological ageing processes. Our data also suggest that post-transcriptional and/or post-translational mechanisms are involved in regulating the activity of these enzymes. Finally, analyses indicate that the Msn2/4p and Hsf1p transcription factors are necessary for HSP26, ALD2/3 and ALD4 gene expression under acetaldehyde stress, while PKA represses the expression of these genes.

Acetaldehyde↗
PubMed2005

Retention of browning compounds by yeasts involved in the winemaking of sherry type wines.

Wine model solutions were used to study the ability of dehydrated yeasts to retain the brown products formed in the reaction between (+)-catechin and acetaldehyde. Saccharomyces cerevisiae races capensis and bayanus, two typical flor yeasts involved in the biological aging of sherry wines, had a higher capacity to retain coloured compounds than S. cerevisiae fermentative yeast. Of the flor yeasts, capensis exhibited a higher colour reduction capacity than bayanus. Such differences may account for the different rate at which browning compounds are removed at different times of year during the biological aging of wines.

Acetaldehyde↗
PubMed2004

Influence of blending on the content of different compounds in the biological aging of sherry dry wines.

Principal components analysis to examine the effect of blending (viz. the mixing and transfer of wine between cask rows in a "criaderas and solera" system) on metabolic activity in flor yeasts during biological aging of sherry dry wines was carried out. The variables used in the analysis were the wine compounds most deeply involved in the flor yeast metabolism, namely ethanol, acetaldehyde, glycerol, acetic acid, and l-proline. The greatest blending effect was found to be on the third and second "criadera", which are the stages where the yeasts show a high metabolic activity. The stages holding the oldest wine (viz. the first criadera and the solera) exhibited no differences before and after blending; therefore, the yeasts have a decreased biological activity in them and physical-chemical aging processes seemingly prevail over it.

Acetaldehyde↗
PubMed2004

Diversity of Y region at HML locus in a Saccharomyces cerevisiae strain isolated from a Sardinian wine.

Several mutations in genes involved in Saccharomyces mating type switching may affect the homothallic behaviour in wine yeasts. In this study the semi-homothallic (Hq) segregation of a flor wine yeast strain was analysed. We aimed to understand the molecular basis of this behaviour in a flor autochthonous strain, verifying the MAT locus status by a PCR-based HO gene disruption and sequencing of the Y region of the HML, HMR and MAT loci, after nested PCR. Presence of ORFs a1 and a2 in the Y region of the HML locus was found. At the ORF a2 at HML locus, a mutation in the stop codon was found, so the a2 ORF contains 33 more bases.

Amino Acid Sequence↗
PubMedDate not supplied

Increased concentrations and lateral asymmetry of amygdala dopamine in schizophrenia.

There is a growing body of evidence in support of the view of schizophrenia as a dysfunction of the left temporal lobe. This hypothesis, first proposed by Flor-Henry, stemmed from the frequently observed association of schizophreniform psychoses with left-sided temporal lobe epilepsy. As yet the evidence is solely clinical, with a wide range of psychological and physiological measurements indicating a left hemisphere disorder in patients with schizophrenia. It is not, however, inconsistent with the major neurochemical hypothesis of schizophrenia, which proposes an increase in dopaminergic neurotransmission which can be blocked by neuroleptic drugs. One region of the medial temporal lobe, the amygdala, receives a major dopaminergic innervation from the ventral tegmental area. In fact this meso-limbic dopaminergic tract, which also innervates the nucleus accumbens and olfactory tubercule, has been implicated in psychosis and in antipsychotic drug action. We have attempted here to test whether there is a neurochemical correlate of the Flor-Henry hypothesis using brain tissue collected post mortem from schizophrenic patients and controls. The results indicate that a specific increase of dopamine is found in the amygdalae in the left cerebral hemisphere of the schizophrenic group.

Aged↗
PubMed2003

Florfenicol resistance in Salmonella enterica serovar Newport mediated by a plasmid related to R55 from Klebsiella pneumoniae.

Florfenicol resistance has emerged over the past few years in multidrug-resistant Salmonella enterica serovars Typhimurium, Agona and Paratyphi B. The floR gene encoding florfenicol resistance is chromosomally located in these serovars within a genomic island of 43 kb called SGI1 (Salmonella genomic island 1). In the present study, we characterized florfenicol resistance in a strain of S. enterica serovar Newport isolated from a turkey in 1990 and that lacked SGI1. Florfenicol resistance was mediated by a conjugative plasmid related to R55 from Klebsiella pneumoniae, which was characterized initially in the 1970s and harbours a gene 95% identical to floR.

Animals↗
PubMed2006

Chloramphenicol and kanamycin resistance among porcine Escherichia coli in Ontario.

OBJECTIVES: The purpose of this study was to compare the distribution of chloramphenicol and kanamycin resistance genes across three populations of porcine Escherichia coli. METHODS: PCR was used to assess the distribution of the major chloramphenicol and kanamycin resistance genes catA1, cmlA and floR, and aphA1, aphA2 and aadB in enterotoxigenic E. coli (ETEC), non-ETEC isolates from cases of diarrhoea and commensal E. coli from healthy pigs. Associations between these genes and resistance genes for other antimicrobials or virulence genes were assessed. RESULTS: The chloramphenicol and kanamycin resistance genes were distributed differently among the three E. coli populations. While aphA1, aphA2 and aadB were evenly distributed among resistant ETEC, non-ETEC and commensals, the catA1 gene was significantly more frequent in ETEC than in non-ETEC and commensals. Transformation experiments confirmed statistical associations by demonstrating that elt, estB, astA, aadA and sul1 were located with catA1 on a large ETEC plasmid. Plasmids carrying cmlA also carried sul3 and aadA. Other plasmids carrying floR and aadB also carried tet(A), sul2, strA/strB, bla(CMY-2) and occasionally aac(3)IV. CONCLUSIONS: The clustering of genes observed is a likely cause for chloramphenicol resistance persistence. Similar to tetracycline, chloramphenicol resistance genes are physically linked to virulence genes. This is not the case for kanamycin resistance determinants, which were linked to other resistance genes only.

Animals↗
PubMed2005

Resistance pattern and assessment of phenicol agents' minimum inhibitory concentration in multiple drug resistant Chryseobacterium isolates from fish and aquatic habitats.

AIMS: To assess the susceptibility of Chryseobacterium isolates of fish and aquatic habitats to antimicrobial compounds. Special attention was paid to the resistance to chloramphenicol and florfenicol, a phenicol derivative recently licensed for use in veterinary medicine and fish farming. METHODS AND RESULTS: Sixty-seven Chryseobacterium spp. isolates and reference strains, originating mainly from different aquatic habitats, were tested using the disk-diffusion method. In addition, agar dilution was used for assessing minimum inhibitory concentration of chloramphenicol and florfenicol. In spite of (i) conditions that hampered properly standardized experiments and (ii) the heterogeneity of the isolates resulting in some aberrant values in diffusion, correlation between the two methods was confirmed. Most of the isolates exhibited considerable multiresistance to most antimicrobial drug families, and many were clearly resistant to phenicols. Molecular investigations conducted on 10 strains selected for high resistance to florfenicol did not establish the existence of floR or cmlA genes currently reported in the literature as responsible for florfenicol resistance. Nevertheless, when an efflux pump inhibitor, phenyl-arginin-beta-naphthylamide, was combined with diffusion tests, drug susceptibility to florfenicol was restored, suggesting that Chryseobacterium's resistance to this molecule is under the control of efflux mechanisms. CONCLUSIONS: Constitutive multiresistance to antibiotics is common in chryseobacteria isolated from the aquatic environment. Although no gene related to the floR family could be detected, efflux mechanisms could partly support the resistance to phenicols. SIGNIFICANCE AND IMPACT OF THE STUDY: These results explain the difficulty of treatment and clearly reflect the properties previously reported in Chryseobacterium isolates of human origin. Because several species have been involved in opportunistic infections in humans, the possible role of aquatic organisms as a source of infection should be considered.

Animals↗
PubMed2002

Characterization of variant Salmonella genomic island 1 multidrug resistance regions from serovars Typhimurium DT104 and Agona.

Strains of multidrug-resistant Salmonella enterica serovar Typhimurium DT104 (DT104) and S. enterica serovar Agona (Agona) have been found to harbor Salmonella genomic island 1 (SGI1), a 43-kb genomic region that contains many of the drug resistance genes. Such strains are resistant to ampicillin (pse-1), chloramphenicol/florfenicol (floR), streptomycin/spectinomycin (aadA2), sulfonamides (sul1), and tetracycline [tet(G)] (commonly called the ACSSuT phenotype). All five resistance genes are found in a 13-kb multidrug resistance (MDR) region consisting of an unusual class I integron structure related to In4. We examined DT104 and Agona strains that exhibited other resistance phenotypes to determine if the resistance genes were associated with variant SGI1 MDR regions. All strains were found to harbor variant SGI1-like elements by using a combination of Southern hybridization, PCR mapping, and sequencing. Variant SGI1-like elements were found with MDR regions consisting of (i) an integron consisting of the SGI1 MDR region with the addition of a region containing a putative transposase gene (orf513) and dfrA10 located between duplicated qacEDelta1/sulI genes (SGI1-A; ACSSuTTm); (ii) an integron with either an aadA2 (SSu) or a pse-1 (ASu) cassette (SGI1-C and SGI1-B, respectively); (iii) an integron consisting of the SGI1-C MDR region plus an orf513/dfrA10 region as in SGI1-A (SGI1-D; ASSuTm; ampicillin resistance due to a TEM beta-lactamase); and (iv) an integron related to that in SGI1 but which contains a 10-kb inversion between two copies of IS6100, one which is inserted in floR (SGI1-E; ASSuT). We hypothesize that the MDR of SGI1 is subject to recombinational events that lead to the various resistance phenotypes in the Salmonella strains in which it is found.

Amino Acid Sequence↗