Journal articles on the topic 'Donor strains'
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1
Laskus, Tomasz, Lian-Fu Wang, Marek Radkowski, Hugo Vargas, Marek Nowicki, Jeffrey Wilkinson, and Jorge Rakela. "Exposure of Hepatitis C Virus (HCV) RNA-Positive Recipients to HCV RNA-Positive Blood Donors Results in Rapid Predominance of a Single Donor Strain and Exclusion and/or Suppression of the Recipient Strain." Journal of Virology 75, no. 5 (March 1, 2001): 2059–66. http://dx.doi.org/10.1128/jvi.75.5.2059-2066.2001.
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ABSTRACT We have analyzed three cases of hepatitis C virus (HCV)-infected recipients who received blood from HCV-infected donors. Two recipients were exposed to two different HCV RNA-positive donors, and one was exposed to a single donor. All parental genomes from the actual infecting units of blood and the recipients were defined, and their presence in the follow-up serum samples was determined using sensitive strain-specific assays. The strain from one of the donors was found to predominate in all recipients' serum samples collected throughout the follow-up period of 10 to 30 months. In two recipients exposed to two infected donors, the strain from the second donor was occasionally found at very low level. However, the original recipients' strains were not detected. Our observations show that HCV-infected individuals can be superinfected with different strains, and this event may lead to eradication or suppression of the original infecting strain. Furthermore, our findings demonstrate that simultaneous exposure to multiple HCV strains may result in concomitant infection by more than one strain, although a single strain could rapidly establish its dominance. The results of the present study suggest the existence of competition among infecting HCV strains which determines the ultimate outcome of multiple HCV exposure.
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Zhu, Raymond, Robert Pesun, Caroline Pampolina, Elke Jackson, George Bowden, Teresa Zelinski, and Archibald McNicol. "A role for immunoglobulin G in donor-specific Streptococcus sanguis-induced platelet aggregation." Thrombosis and Haemostasis 95, no. 02 (2006): 288–93. http://dx.doi.org/10.1160/th05-07-0491.
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SummaryThere is increasing evidence fora relationship between bacterial infections and several cardiovascular disorders. Although the precise mechanism(s) underlying this association is unknown, the direct activation of platelets by bacteria is one possibility. Individual strains of S. sanguis activate platelets in a non-uniform, donor-dependent manner. In the current study, platelet aggregation profiles were obtained for fourteen donors in response to four strains of S. sanguis (2017–78, 133–79, SK112, SK108a) and one of S. gordonii (SK8). The platelets from all donors responded to strains 2017–78 and 133–79,whereas strains SK112, SK8 and SK108a caused aggregation in one, five and twelve donors, respectively. Immunoglobulin G (IgG) binding to strains 2017–78, 133–79 and SK108a were significantly greater than to strains SK112 and SK8. Absorption of IgG by strain 2017–78 caused significant decreases in IgG binding, and platelet aggregation in response, to all strains. Single-strand conformational polymorphisms were observed in the FcγRIIA gene from four donors. Sequencing revealed two known and two novel point mutations, none of which correlated with the aggregation profile. Thus, platelet activation to the various strains depends ona common IgG and, while in most cases the level of IgG binding to S. sanguis determines platelet responsiveness, neither the levels of IgG nor FcγRIIA polymorphisms can fully account for donor variability.
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Ochi, Kentaro, Maho Tokuda, Kosuke Yanagiya, Chiho Suzuki-Minakuchi, Hideaki Nojiri, Masahiro Yuki, Moriya Ohkuma, Kazuhide Kimbara, and Masaki Shintani. "Oxygen concentration affects frequency and range of transconjugants for the incompatibility (Inc) P-1 and P-7 plasmids pBP136 and pCAR1." Bioscience, Biotechnology, and Biochemistry 85, no. 4 (December 26, 2020): 1005–15. http://dx.doi.org/10.1093/bbb/zbaa118.
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ABSTRACT The frequency of transconjugants were compared for the incompatibility (Inc) P-1 and P-7 plasmids pBP136 and pCAR1 under aerobic and anaerobic conditions. Filter mating assays were performed with one donor strain and one recipient strain using different donors of Pseudomonas and recipient strains, including Pseudomonas, Pantoea, and Buttiauxella. Under anaerobic condition, frequencies of transconjugants for both plasmids were 101-103-fold lower than those under aerobic condition regardless of whether aerobically or anaerobically grown donors and recipients were used. To compare the transconjugant ranges under aerobic and anaerobic conditions, conjugation was performed between the donor of pBP136 and recipient bacteria extracted from environmental samples. Several transconjugants were uniquely obtained from each aerobic or anaerobic condition. Our findings indicate that a plasmid can differently spread among bacteria depending on the oxygen concentrations of the environment.
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Shi, Xian’ai, Hang Wang, Hao Wang, Zhiming Wang, and Chun Meng. "Transferring chromosome DNA fragments from multiple donor cells into a host strain for yeast strain improvement." Canadian Journal of Microbiology 58, no. 6 (June 2012): 760–66. http://dx.doi.org/10.1139/w2012-036.
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Based on a common biological phenomenon — homologous recombination — a novel method was developed by transferring chromosome DNA fragments extracted from multiple donor cells into a host strain. Through this method of transferring DNA fragments, foreign DNA fragments are introduced into one host cell and multiple positive traits from multiple strains may be integrated into the host strain. We first confirmed its feasibility in both prokaryotic and eukaryotic cells by selecting reverse mutants to prototrophy from auxotrophic strains through receiving chromosomal DNA fragments of wild-type parental strains. We then applied this method to Saccharomyces cerevisiae to improve its ethanol and temperature tolerance. We introduced donor chromosome DNA fragments from different S. cerevisiae strains with improvements in ethanol or temperature tolerance into a common strain S. cerevisiae and obtained a strain with much superior ethanol and temperature tolerance. The results showed that the Transferring DNA Fragments method provides a new way for strain breeding.
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Thomas, D. John I., J. Alun W. Morgan, John M. Whipps, and Jon R. Saunders. "Plasmid Transfer between the Bacillus thuringiensis Subspecies kurstaki andtenebrionis in Laboratory Culture and Soil and in Lepidopteran and Coleopteran Larvae." Applied and Environmental Microbiology 66, no. 1 (January 1, 2000): 118–24. http://dx.doi.org/10.1128/aem.66.1.118-124.2000.
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ABSTRACT Plasmid transfer between Bacillus thuringiensis subsp.kurstaki HD1 and B. thuringiensis subsp.tenebrionis donor strains and a streptomycin-resistantB. thuringiensis subsp. kurstaki recipient was studied under environmentally relevant laboratory conditions in vitro, in soil, and in insects. Plasmid transfer was detected in vitro at temperatures of 5 to 37°C, at pH 5.9 to 9.0, and at water activities of 0.965 to 0.995, and the highest transfer ratios (up to 10−1 transconjugant/donor) were detected within 4 h. In contrast, no plasmid transfer was detected in nonsterile soil, and rapid formation of spores by the introduced strains probably contributed most to the lack of plasmid transfer observed. When aB. thuringiensis subsp. kurstaki strain was used as the donor strain, plasmid transfer was detected in killed susceptible lepidopteran insect (Lacanobia oleracea) larvae but not in the nonsusceptible coleopteran insect Phaedon chocleriae. When a B. thuringiensis subsp.tenerbrionis strain was used as the donor strain, no plasmid transfer was detected in either of these insects even when they were killed. These results show that in larger susceptible lepidopteran insects there is a greater opportunity for growth of B. thuringiensis strains, and this finding, combined with decreased competition due to a low initial background bacterial population, can provide suitable conditions for efficient plasmid transfer in the environment.
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Signorini, Lucia, Maria Dolci, Evaldo Favi, Caterina Colico, Mariano Ferraresso, Rosalia Ticozzi, Giuseppe Basile, Pasquale Ferrante, and Serena Delbue. "Viral Genomic Characterization and Replication Pattern of Human Polyomaviruses in Kidney Transplant Recipients." Viruses 12, no. 11 (November 9, 2020): 1280. http://dx.doi.org/10.3390/v12111280.
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Human Polyomavirus (HPyV) infections are common, ranging from 60% to 100%. In kidney transplant (KTx) recipients, HPyVs have been associated with allograft nephropathy, progressive multifocal leukoencephalopathy, and skin cancer. Whether such complications are caused by viral reactivation or primary infection transmitted by the donor remains debated. This study aimed to investigate the replication pattern and genomic characterization of BK Polyomavirus (BKPyV), JC Polyomavirus (JCPyV), and Merkel Cell Polyomavirus (MCPyV) infections in KTx. Urine samples from 57 KTx donor/recipient pairs were collected immediately before organ retrieval/transplant and periodically up to post-operative day 540. Specimens were tested for the presence of BKPyV, JCPyV, and MCPyV genome by virus-specific Real-Time PCR and molecularly characterized. HPyVs genome was detected in 49.1% of donors and 77.2% of recipients. Sequences analysis revealed the archetypal strain for JCPyV, TU and Dunlop strains for BKPyV, and IIa-2 strain for MCPyV. VP1 genotyping showed a high frequency for JCPyV genotype 1 and BKPyV genotype I. Our experience demonstrates that after KTx, HPyVs genome remains stable over time with no emergence of quasi-species. HPyVs strains isolated in donor/recipient pairs are mostly identical, suggesting that viruses detected in the recipient may be transmitted by the allograft.
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Weil, Michael M., Barry W. Brown, and Dan M. Serachitopol. "Genotype Selection to Rapidly Breed Congenic Strains." Genetics 146, no. 3 (July 1, 1997): 1061–69. http://dx.doi.org/10.1093/genetics/146.3.1061.
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Congenic strains can now be constructed guided by the transmission of DNA markers. This allows not only selection for transmission of a desired, donor-derived differential region but also selection against the transmission of unwanted donor origin genomic material. The additional selection capacity should allow congenic strains to be produced in fewer generations than is possible with random backcrosses. Here, we consider modifications of a standard backcross breeding scheme to produce congenic mice by the inclusion of genotype-based selective breeding strategies. Simulation is used to evaluate the consequences of each strategy on the number of chromosomes that contain unwanted, donor-derived genetic material and the average length of this unwanted donor DNA for each backcross generation. Our prototypic strategy was to choose a single mouse to sire each generation using criteria designed to select against the transmission of chromosomes, other than the one containing the replacement genomic region, that contain any donor origin sequence at all. This chromosome elimination strategy resulted in an average of 16.4 chromosomes free of donor DNA in mice of the third backcross (N3) generation. A strategy based solely on positive selection for the replacement region required six backcross generations to achieve the same results.
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Blesa, Alba, Ignacio Baquedano, Sandra González-de la Fuente, Mario Mencía, and José Berenguer. "Integrative and Conjugative Element ICETh1 Functions as a Pangenomic DNA Capture Module in Thermus thermophilus." Microorganisms 8, no. 12 (December 21, 2020): 2051. http://dx.doi.org/10.3390/microorganisms8122051.
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Transjugation is an unconventional conjugation mechanism in Thermus thermophilus (Tth) that involves the active participation of both mating partners, encompassing a DNA secretion system (DSS) in the donor and an active natural competence apparatus (NCA) in the recipient cells. DSS is encoded within an integrative and conjugative element (ICETh1) in the strain Tth HB27, whereas the NCA is constitutively expressed in both mates. Previous experiments suggested the presence of multiple origins of transfer along the genome, which could generate genomic mosaicity among the progeny. Here, we designed transjugation experiments between two closely related strains of Tth with highly syntenic genomes, containing enough single nucleotide polymorphisms to allow precise parenthood analysis. Individual clones from the progeny were sequenced, revealing their origin as derivatives of our ICETh1-containing intended “donor” strain (HB27), which had acquired separate fragments from the genome of the ICETh1-free HB8 cells, which are our intended recipient. Due to the bidirectional nature of transjugation, only assays employing competence-defective HB27 derivatives as donors allowed the recovery of HB8-derived progeny. These results show a preference for a retrotransfer mechanism in transjugation in ICETh1-bearing strains, supporting an inter-strain gene-capture function for ICETh1. This function could benefit the donor-capable host by facilitating the acquisition of adaptive traits from external sources, ultimately increasing the open pangenome of Thermus, maximizing the potential repertoire of physiological and phenotypical traits related to adaptation and speciation.
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Ferrières, Lionel, Gaëlle Hémery, Toan Nham, Anne-Marie Guérout, Didier Mazel, Christophe Beloin, and Jean-Marc Ghigo. "Silent Mischief: Bacteriophage Mu Insertions Contaminate Products of Escherichia coli Random Mutagenesis Performed Using Suicidal Transposon Delivery Plasmids Mobilized by Broad-Host-Range RP4 Conjugative Machinery." Journal of Bacteriology 192, no. 24 (October 8, 2010): 6418–27. http://dx.doi.org/10.1128/jb.00621-10.
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ABSTRACT Random transposon mutagenesis is the strategy of choice for associating a phenotype with its unknown genetic determinants. It is generally performed by mobilization of a conditionally replicating vector delivering transposons to recipient cells using broad-host-range RP4 conjugative machinery carried by the donor strain. In the present study, we demonstrate that bacteriophage Mu, which was deliberately introduced during the original construction of the widely used donor strains SM10 λpir and S17-1 λpir, is silently transferred to Escherichia coli recipient cells at high frequency, both by hfr and by release of Mu particles by the donor strain. Our findings suggest that bacteriophage Mu could have contaminated many random-mutagenesis experiments performed on Mu-sensitive species with these popular donor strains, leading to potential misinterpretation of the transposon mutant phenotype and therefore perturbing analysis of mutant screens. To circumvent this problem, we precisely mapped Mu insertions in SM10 λpir and S17-1 λpir and constructed a new Mu-free donor strain, MFDpir, harboring stable hfr-deficient RP4 conjugative functions and sustaining replication of Π-dependent suicide vectors. This strain can therefore be used with most of the available transposon-delivering plasmids and should enable more efficient and easy-to-analyze mutant hunts in E. coli and other Mu-sensitive RP4 host bacteria.
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Zhilina, Tatyana N., Daria G. Zavarzina, Ekaterina N. Detkova, Ekaterina O. Patutina, and Boris B. Kuznetsov. "Fuchsiella ferrireducens sp. nov., a novel haloalkaliphilic, lithoautotrophic homoacetogen capable of iron reduction, and emendation of the description of the genus Fuchsiella." International Journal of Systematic and Evolutionary Microbiology 65, Pt_8 (August 1, 2015): 2432–40. http://dx.doi.org/10.1099/ijs.0.000278.
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Two strains of haloalkaliphilic homoacetogenic bacteria capable of iron reduction, Z-7101T and Z-7102, were isolated from soda lake Tanatar III (Altai, Russia). Cells of both strains were flexible, motile, Gram-negative, spore-forming rods. The strains were mesophilic and obligately alkaliphilic: the pH range for growth was 8.5–10.2 (pHopt 9.8). Growth depended on carbonate and chloride ions. The strains were able to grow chemolithoautotrophically on H2+CO2, producing acetate as the only metabolic product. In medium with carbonates as the only potential electron acceptor, the following substrates were utilized for chemo-organotrophic growth: pyruvate, lactate, ethanol, 1-propanol, ethylene glycol and 1-butanol. Strain Z-7101T was able to reduce nitrate, selenate, thiosulfate and anthraquinone 2,6-disulfonate with ethanol as an electron donor. It was also able to reduce synthesized ferrihydrite to siderite with molecular hydrogen or organic compounds, including acetate and formate, as electron donors. It was able to reduce S0 with acetate or formate as electron donors. The DNA G+C content of strain Z-7101T was 34.6 mol%. 16S rRNA gene sequence analysis showed that strains Z-7101T and Z-7102 were members of the order Halanaerobiales and family Halobacteroidaceae, clustering with Fuchsiella alkaliacetigena Z-7100T (98.9–98.4 % similarity). DNA–DNA hybridization was 63.0 % between strain Z-7101T and F. alkaliacetigena Z-7100T. Based on morphological and physiological differences from F. alkaliacetigena Z-7100T and the results of phylogenetic analysis and DNA–DNA hybridization, it is proposed to assign strains Z-7101T and Z-7102 ( = DSM 26052 = VKM B-2790) to the novel species Fuchsiella ferrireducens sp. nov. The type strain is strain Z-7101T ( = DSM 26031T = VKM B-2766T).
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Pappas, Katherine M., and Stephen C. Winans. "Plant Transformation by Coinoculation with a Disarmed Agrobacterium tumefaciens Strain and an Escherichia coli Strain Carrying Mobilizable Transgenes." Applied and Environmental Microbiology 69, no. 11 (November 2003): 6731–39. http://dx.doi.org/10.1128/aem.69.11.6731-6739.2003.
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ABSTRACT Transformation of Nicotiana tabacum leaf explants was attempted with Escherichia coli as a DNA donor either alone or in combination with Agrobacterium tumefaciens. We constructed E. coli donor strains harboring either the promiscuous IncP-type or IncN-type conjugal transfer system and second plasmids containing the respective origins of transfer and plant-selectable markers. Neither of these conjugation systems was able to stably transform plant cells at detectable levels, even when VirE2 was expressed in the donor cells. However, when an E. coli strain expressing the IncN-type conjugation system was coinoculated with a disarmed A. tumefaciens strain, plant tumors arose at high frequencies. This was caused by a two-step process in which the IncN transfer system mobilized the entire shuttle plasmid from E. coli to the disarmed A. tumefaciens strain, which in turn processed the T-DNA and transferred it to recipient plant cells. The mobilizable plasmid does not require a broad-host-range replication origin for this process to occur, thus reducing its size and genetic complexity. Tumorigenesis efficiency was further enhanced by incubation of the bacterial strains on medium optimized for bacterial conjugation prior to inoculation of leaf explants. These techniques circumvent the need to construct A. tumefaciens strains containing binary vectors and could simplify the creation of transgenic plants.
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Hardiman, C. A., R. A. Weingarten, S. Conlan, P. Khil, J. P. Dekker, A. J. Mathers, A. E. Sheppard, J. A. Segre, and K. M. Frank. "Horizontal Transfer of Carbapenemase-Encoding Plasmids and Comparison with Hospital Epidemiology Data." Antimicrobial Agents and Chemotherapy 60, no. 8 (June 6, 2016): 4910–19. http://dx.doi.org/10.1128/aac.00014-16.
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ABSTRACTCarbapenemase-producing organisms have spread worldwide, and infections with these bacteria cause significant morbidity. Horizontal transfer of plasmids carrying genes that encode carbapenemases plays an important role in the spread of multidrug-resistant Gram-negative bacteria. Here we investigate parameters regulating conjugation using anEscherichia colilaboratory strain that lacks plasmids or restriction enzyme modification systems as a recipient and also using patient isolates as donors and recipients. Because conjugation is tightly regulated, we performed a systematic analysis of the transfer ofKlebsiella pneumoniaecarbapenemase (blaKPC)-encoding plasmids into multiple strains under different environmental conditions to investigate critical variables. We used fourblaKPC-carrying plasmids isolated from patient strains obtained from two hospitals: pKpQIL and pKPC-47e from the National Institutes of Health, and pKPC_UVA01 and pKPC_UVA02 from the University of Virginia. Plasmid transfer frequency differed substantially between different donor and recipient pairs, and the frequency was influenced by plasmid content, temperature, and substrate, in addition to donor and recipient strain. pKPC-47e was attenuated in conjugation efficiency across all conditions tested. Despite its presence in multiple clinical species, pKPC_UVA01 had lower conjugation efficiencies than pKpQIL into recipient strains. The conjugation frequency of these plasmids intoK. pneumoniaeandE. colipatient isolates ranged widely without a clear correlation with clinical epidemiological data. Our results highlight the importance of each variable examined in these controlled experiments. Thein vitromodels did not reliably predict plasmid mobilization observed in a patient population, indicating that further studies are needed to understand the most important variables affecting horizontal transferin vivo.
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Kos, Ivan, Milena Jadrijević-Mladar, Ivan Butula, Mladen Biruš, Gordana Maravić-Vlahoviček, and Sanja Dabelić. "Synthesis, antibacterial and cytotoxic activity evaluation of hydroxyurea derivatives." Acta Pharmaceutica 63, no. 2 (June 1, 2013): 175–91. http://dx.doi.org/10.2478/acph-2013-0014.
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5 Synthesis and biological evaluation of a series (N = 16) of cyclic and acyclic hydroxyurea derivatives, including benzotriazole-, isocyanuric acid- and biuret-containing compounds, are disclosed. 1-N-(benzyloxycarbamoyl)benzotriazole was used as a benzyloxyisocyanate donor, a useful intermediate in the preparation of substituted hydroxyurea. Antibacterial activities of synthesized hydroxyurea derivatives were tested on three E. coli strains, i.e., a strain susceptible to antibiotics, a strain resistant to macrolide antibiotics and a strain resistant to aminoglycoside antibiotics. Six compounds (three acyclic and three cyclic hydroxyureas) showed growth inhibition of the tested E. coli strains, with different specificity toward each strain. Results of the cytotoxic activity evaluation revealed that twelve out of sixteen test compounds were cytotoxic to human acute monocytic leukemia THP-1 and/or human acute T cell leukemia Jurkat cell line. 1-(N-hydroxycarbamoyl) benzotriazole () increased the metabolic activity of both cell lines. Two compounds, 1-(N-hydroxycarbamoyl) benzotriazole (5) and N,N’,N’’-trihydroxybiuret (15), were identified as potential NO donors.
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Van Zutphen, L. F. M., M. Den Bieman, A. Lankhorst, and P. Demant. "Segregation of genes from donor strain during the production of recombinant congenic strains." Laboratory Animals 25, no. 3 (July 1991): 193–97. http://dx.doi.org/10.1258/002367791780808329.
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Licht, Tine Rask, Dorthe Laugesen, Lars Bogø Jensen, and Bodil Lund Jacobsen. "Transfer of the Pheromone-Inducible Plasmid pCF10 among Enterococcus faecalis Microorganisms Colonizing the Intestine of Mini-Pigs." Applied and Environmental Microbiology 68, no. 1 (January 2002): 187–93. http://dx.doi.org/10.1128/aem.68.1.187-193.2002.
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ABSTRACT A new animal model, the streptomycin-treated mini-pig, was developed in order to allow colonization of defined strains of Enterococcus faecalis in numbers sufficient to study plasmid transfer. Transfer of the pheromone-inducible pCF10 plasmid between streptomycin-resistant strains of E. faecalis OG1 was investigated in the model. The plasmid encodes resistance to tetracycline. Numbers of recipient, donor, and transconjugant bacteria were monitored by selective plating of fecal samples, and transconjugants were subsequently verified by PCR. After being ingested by the mini-pigs, the recipient strain persisted in the intestine at levels between 106 and 107 CFU per g of feces throughout the experiment. The donor strain, which carried different resistance markers but was otherwise chromosomally isogenic to the recipient strain, was given to the pigs 3 weeks after the recipient strain. The donor cells were initially present in high numbers (106 CFU per g) in feces, but they did not persist in the intestine at detectable levels. Immediately after introduction of the donor bacteria, transconjugant cells appeared and persisted in fecal samples at levels between 103 and 104 CFU per g until the end of the experiment. These observations showed that even in the absence of selective tetracycline pressure, plasmid pCF10 was transferred from ingested E. faecalis cells to other E. faecalis organisms already present in the intestinal environment and that the plasmid subsequently persisted in the intestine.
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Ike, Yasuyoshi, Koichi Tanimoto, Haruyoshi Tomita, Kunio Takeuchi, and Shuhei Fujimoto. "Efficient Transfer of the Pheromone-IndependentEnterococcus faecium Plasmid pMG1 (Gmr) (65.1 Kilobases) to Enterococcus Strains during Broth Mating." Journal of Bacteriology 180, no. 18 (September 15, 1998): 4886–92. http://dx.doi.org/10.1128/jb.180.18.4886-4892.1998.
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ABSTRACT Plasmid pMG1 (65.1 kb) was isolated from a gentamicin-resistantEnterococcus faecium clinical isolate and was found to encode gentamicin resistance. EcoRI restriction of pMG1 produced five fragments, A through E, with molecular sizes of 50.2, 11.5, 2.0, 0.7, and 0.7 kb, respectively. The clockwise order of the fragments was ACDEB. pMG1 transferred at high frequency toEnterococcus strains in broth mating. pMG1 transferred between Enterococcus faecalis strains, betweenE. faecium strains, and between E. faecium andE. faecalis strains at a frequency of approximately 10−4 per donor cell after 3 h of mating. The pMG1 transfers were not induced by the exposure of the donor cell to culture filtrates of plasmid-free E. faecalis FA2-2 or an E. faecium strain. Mating aggregates were not observed by the naked eye during broth mating. Small mating aggregates of several cells in the broth matings were observed by microscopy, while no aggregates of donor cells which had been exposed to a culture filtrate of E. faecalis FA2-2 or an E. faecium strain were observed, even by microscopy. pMG1 DNA did not show any homology in Southern hybridization with that of the pheromone-responsive plasmids and broad-host-range plasmids pAMβ1 and pIP501. These results indicate that there is another efficient transfer system in the conjugative plasmids of Enterococcus and that this system is different from the pheromone-induced transfer system of E. faecalis plasmids.
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Zhao, Shuqing, Margaret Duncan, Joshua Tomberg, Christopher Davies, Magnus Unemo, and Robert A. Nicholas. "Genetics of Chromosomally Mediated Intermediate Resistance to Ceftriaxone and Cefixime in Neisseria gonorrhoeae." Antimicrobial Agents and Chemotherapy 53, no. 9 (June 15, 2009): 3744–51. http://dx.doi.org/10.1128/aac.00304-09.
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ABSTRACT All strains of Neisseria gonorrhoeae with reduced susceptibility to ceftriaxone and cefixime (cephalosporin-intermediate-resistant [Cephi] strains) contain a mosaic penA allele encoding penicillin-binding protein 2 (PBP 2) with nearly 60 amino acid differences compared to the sequence of wild-type PBP 2, together with a set of resistance determinants (i.e., mtrR, penB, and/or ponA1) that are required for high-level penicillin resistance. To define the individual contributions of these determinants to reduced susceptibility to ceftriaxone and cefixime, we created isogenic strains containing the mosaic penA allele from the Cephi strain 35/02 (penA35) together with one or more of the other resistance determinants and determined the MICs of penicillin G, ceftriaxone, and cefixime. The majority of cefixime resistance is conferred by the penA35 allele, with only a small contribution coming from mtrR and penB, whereas ceftriaxone resistance is nearly equally dependent upon mtrR and penB. Unlike high-level penicillin resistance, the ponA1 allele does not appear to be important for Cephi. A strain containing all four determinants has increased resistance to ceftriaxone and cefixime but not to the levels that the donor Cephi strain does, suggesting that Cephi strains, similar to high-level-penicillin-resistant strains, contain an additional unknown determinant that is required to reach donor levels of resistance. Our data also suggest that the original Cephi strains arose from the transformation of penA genes from commensal Neisseria species into a penicillin-resistant strain already harboring mtrR, penB, ponA1, and the unknown gene(s) involved in high-level penicillin resistance.
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Peng, Peng, Tobias Goris, Yue Lu, Bart Nijsse, Anna Burrichter, David Schleheck, Jasper J. Koehorst, et al. "Organohalide-respiring Desulfoluna species isolated from marine environments." ISME Journal 14, no. 3 (January 2, 2020): 815–27. http://dx.doi.org/10.1038/s41396-019-0573-y.
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AbstractThe genus Desulfoluna comprises two anaerobic sulfate-reducing strains, D. spongiiphila AA1T and D. butyratoxydans MSL71T, of which only the former was shown to perform organohalide respiration (OHR). Here we isolated a third strain, designated D. spongiiphila strain DBB, from marine intertidal sediment using 1,4-dibromobenzene and sulfate as the electron acceptors and lactate as the electron donor. Each strain harbors three reductive dehalogenase gene clusters (rdhABC) and corrinoid biosynthesis genes in their genomes, and dehalogenated brominated but not chlorinated organohalogens. The Desulfoluna strains maintained OHR in the presence of 20 mM sulfate or 20 mM sulfide, which often negatively affect other organohalide-respiring bacteria. Strain DBB sustained OHR with 2% oxygen in the gas phase, in line with its genetic potential for reactive oxygen species detoxification. Reverse transcription-quantitative PCR revealed differential induction of rdhA genes in strain DBB in response to 1,4-dibromobenzene or 2,6-dibromophenol. Proteomic analysis confirmed expression of rdhA1 with 1,4-dibromobenzene, and revealed a partially shared electron transport chain from lactate to 1,4-dibromobenzene and sulfate, which may explain accelerated OHR during concurrent sulfate reduction. Versatility in using electron donors, de novo corrinoid biosynthesis, resistance to sulfate, sulfide and oxygen, and concurrent sulfate reduction and OHR may confer an advantage to marine Desulfoluna strains.
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Moens, F., C. Duysburgh, P. van den Abbeele, M. Morera, and M. Marzorati. "Lactobacillus rhamnosus GG and Saccharomyces cerevisiae boulardii exert synergistic antipathogenic activity in vitro against enterotoxigenic Escherichia coli." Beneficial Microbes 10, no. 8 (December 9, 2019): 923–35. http://dx.doi.org/10.3920/bm2019.0064.
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Short-term colonic in vitro batch incubations were performed to elucidate the possible synergistic effects of Lactobacillus rhamnosus GG (CNCM-I-4798) and Saccharomyces cerevisiae boulardii (CNCM-I-1079) (associated in Smebiocta/Smectaflora Protect®) on the colonic microbial fermentation process, as well as their antipathogenic activity against enterotoxigenic Escherichia coli (LMG2092) (ETEC). These incubations adequately simulate the native microbiota and environmental conditions of the proximal colon of both adult and toddler donors, including the colonic mucosal layer. Results indicated that both strains were capable of growing together without showing antagonistic effects. Co-cultivation of both strains resulted in increased butyrate (stimulated by L. rhamnosus GG), propionate (stimulated by S. boulardii), and ethanol (produced by S. boulardii) production compared to the control incubations, revealing the additive effect of both strains. After inoculation of ETEC under simulated dysbiotic conditions, a 40 and 46% reduction in the concentration of ETEC was observed upon addition of both strains during the experiments with the adult and toddler donor, respectively. Furthermore, ETEC toxin levels decreased upon S. boulardii inoculation, probably due to proteolytic activity of this strain, with a synergistic effect being observed upon co-cultivation of L. rhamnosus GG and S. boulardii resulting in a reduction of 57 and 46% for the adult and toddler donor, respectively. Altogether, the results suggest that both probiotics together may help microbiota functionality, in both adults and toddlers and under healthy or impaired conditions, which could be of great interest when the colonic microbiota is dysbiotic and therefore sensitive to pathogenic invasion such as during antibiotic treatment.
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Nguyen, Kiet T., Kristina Piastro, Todd A. Gray, and Keith M. Derbyshire. "Mycobacterial Biofilms Facilitate Horizontal DNA Transfer between Strains of Mycobacterium smegmatis." Journal of Bacteriology 192, no. 19 (July 30, 2010): 5134–42. http://dx.doi.org/10.1128/jb.00650-10.
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ABSTRACT Conjugal transfer of chromosomal DNA between strains of Mycobacterium smegmatis occurs by a novel mechanism. In a transposon mutagenesis screen, three transfer-defective insertions were mapped to the lsr2 gene of the donor strain mc2155. Because lsr2 encodes a nonspecific DNA-binding protein, mutations of lsr2 give rise to a variety of phenotypes, including an inability to form biofilms. In this study, we show that efficient DNA transfer between strains of M. smegmatis occurs in a mixed biofilm and that the process requires expression of lsr2 in the donor but not in the recipient strain. Testing cells from different strata of standing cultures showed that transfer occurred predominantly at the biofilm air-liquid interface, as other strata containing higher cell densities produced very few transconjugants. These data suggest that the biofilm plays a role beyond mere facilitation of cell-cell contact. Surprisingly, we found that under standard assay conditions the recipient strain does not form a biofilm. Taking these results together, we conclude that for transfer to occur, the recipient strain is actively recruited into the biofilm. In support of this idea, we show that donor and recipient cells are present in almost equal numbers in biofilms that produce transconjugants. Our demonstration of genetic exchange between mycobacteria in a mixed biofilm suggests that conjugation occurs in the environment. Since biofilms are considered to be the predominant natural microhabitat for bacteria, our finding emphasizes the importance of studying biological and physical processes that occur between cells in mixed biofilms.
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Warden, Craig H., and Jerome I. Rotter. "Genetics of Complex Disease: From Mouse to Man and Back." Canadian Journal of Gastroenterology 9, no. 3 (1995): 169–74. http://dx.doi.org/10.1155/1995/842672.
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Identification of genes underlying complex traits has been difficult, but combined application of novel methods and mouse models provides new hope. Rare monogenic syndromes, and candidate gene and biochemical approaches are sometimes useful, but each of these approaches also has limitations. Some problems that prevent identification and isolation of genes underlying complex disease can be avoided by the use of whole genome mapping of mouse crosses or of human families. Mice have many advantages for the study of complex disease, including an extensive genetic map. A generic method has recently been developed and applied for detection of quantitative trait loci (QTLs) using whole genome maps of mouse crosses. Availability of more than 200 congenic strains provides another incentive for studies in mice. Congenic strains provide a rich, but previously unexploited, resource for the rapid identification of genes causing complex diseases. A congenic mouse strain is genetically identical to a background strain, except for a small chromosomal region derived from a donor strain. Thus, comparison of a phenotype in a congenic strain with the phenotype in its background strain allows study of the effects of single genes derived from the donor strain, isolated from the effects of other donor strain genes. Application of all or several techniques to complex disease studies in mice and in humans may lead to the identification and understanding of complex diseases whose etiology is currently unknown.
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Seyama, Shoji, Takeaki Wajima, Hidemasa Nakaminami, and Norihisa Noguchi. "Clarithromycin Resistance Mechanisms of Epidemic β-Lactamase-Nonproducing Ampicillin-Resistant Haemophilus influenzae Strains in Japan." Antimicrobial Agents and Chemotherapy 60, no. 5 (March 7, 2016): 3207–10. http://dx.doi.org/10.1128/aac.00163-16.
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ABSTRACTThe aim of this study was to clarify the clarithromycin resistance mechanisms of β-lactamase-nonproducing ampicillin-resistantHaemophilus influenzaestrains. In all clarithromycin-resistant strains, the transcript level ofacrBwas significantly elevated, and these strains had a frameshift mutation inacrR. Introduction of theacrRmutation intoH. influenzaeRd generated a clarithromycin-resistant transformant with the same MIC as the donor strain. Our results indicate that theacrRmutation confers clarithromycin resistance by the increasing the transcription ofacrB.
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Safari, Zahra, Aurélia Bruneau, Magali Monnoye, Mahendra Mariadassou, Catherine Philippe, Kurt Zatloukal, and Philippe Gérard. "Murine Genetic Background Overcomes Gut Microbiota Changes to Explain Metabolic Response to High-Fat Diet." Nutrients 12, no. 2 (January 21, 2020): 287. http://dx.doi.org/10.3390/nu12020287.
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Interactions of diet, gut microbiota, and host genetics play essential roles in the development of metabolic diseases. A/J and C57BL/6J (C57) are two mouse strains known to display different susceptibilities to metabolic disorders. In this context, we analyzed gut microbiota composition in A/J and C57 mice, and assessed its responses to high-fat diet (HFD) and antibiotic (AB) treatment. We also exchanged the gut microbiota between the two strains following AB treatment to evaluate its impact on the metabolism. We showed that A/J and C57 mice have different microbiome structure and composition at baseline. Moreover, A/J and C57 microbiomes responded differently to HFD and AB treatments. Exchange of the gut microbiota between the two strains was successful as recipients’ microbiota resembled donor-strain microbiota. Seven weeks after inoculation, the differences between recipients persisted and were still closer from the donor-strain microbiota. Despite effective microbiota transplants, the response to HFD was not markedly modified in C57 and A/J mice. Particularly, body weight gain and glucose intolerance in response to HFD remained different in the two mouse strains whatever the changes in microbiome composition. This indicated that genetic background has a much stronger impact on metabolic responses to HFD than gut microbiome composition.
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Bi, L., R. Sarkar, T. Naas, AM Lawler, J. Pain, SL Shumaker, V. Bedian, and HH Jr Kazazian. "Further characterization of factor VIII-deficient mice created by gene targeting: RNA and protein studies." Blood 88, no. 9 (November 1, 1996): 3446–50. http://dx.doi.org/10.1182/blood.v88.9.3446.bloodjournal8893446.
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Previously we created two strains of factor VIII-deficient mice by insertion of a neo gene into (1) the 3′ end of exon 16 and (2) exon 17 of the factor VIII gene. Affected mice of both strains have no plasma factor VIII activity, yet are healthy with no spontaneous bleeding. Factor VIII-deficient females bred with affected males survive pregnancy and delivery. We used reverse transcriptase-polymerase chain reaction of liver RNA to characterize factor VIII mRNA processing. Factor VIII mRNA of the exon 16 knockout strain contains neo sequences plus 17 bp of intron 16 due to use of a cryptic donor site in intron 16. All factor VIII mRNA of the exon 17 knockout strain lacks exon 17 and neo sequences. In skipping exon 17, the intron 16 donor site or a cryptic donor site 46 bp 3′ to the intron 16 donor site are used. Thus, factor VIII deficiency in exon 16 knockout mice is due to truncated protein, while in exon 17 knockout mice it is due to either truncated or partially deleted protein. After immunizing exon 16 knockout mice with human recombinant factor VIII, two monoclonal antibodies were obtained that recognize <7 100 pg of mouse factor VIII light chain. Assay of cryoprecipitate from the plasma of affected mice failed to show factor VIII light chain.
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Samuels, A. Lacey, Erich Lanka, and Julian E. Davies. "Conjugative Junctions in RP4-Mediated Mating ofEscherichia coli." Journal of Bacteriology 182, no. 10 (May 15, 2000): 2709–15. http://dx.doi.org/10.1128/jb.182.10.2709-2715.2000.
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ABSTRACT The physical association of bacteria during conjugation mediated by the IncPα plasmid RP4 was investigated. Escherichia colimating aggregates prepared on semisolid medium were ultrarapidly frozen using copper block freezing, followed by freeze substitution, thin sectioning, and transmission electron microscopy. In matings where the donor bacteria contained conjugative plasmids, distinctive junctions were observed between the outer membranes of the aggregates of mating cells. An electron-dense layer linked the stiffly parallel outer membranes in the junction zone, but there were no cytoplasmic bridges nor apparent breaks in the cell walls or membranes. In control experiments where the donors lacked conjugative plasmids, junctions were not observed. Previous studies have shown that plasmid RP4 carries operons for both plasmid DNA processing (Tra1) and mating pair formation (Tra2). In matings where donor strains carried Tra2 only or Tra2 plus the pilin-processing protease TraF, junctions were found but they were shorter and more interrupted than the wild type. If the donor strain had the pilin gene knocked out (trbC), junctions were still found. Thus, it appears that the electron-dense layer between the outer membranes of the conjugating cells is not composed of pilin.
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Gord Noshahri, Najme, Jamshid Fooladi, Christoph Syldatk, Ulrike Engel, Majid M. Heravi, Mohammad Zare Mehrjerdi, and Jens Rudat. "Screening and Comparative Characterization of Microorganisms from Iranian Soil Samples Showing ω-Transaminase Activity toward a Plethora of Substrates." Catalysts 9, no. 10 (October 22, 2019): 874. http://dx.doi.org/10.3390/catal9100874.
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In this study, soil microorganisms from Iran were screened for ω-transaminase (ω-TA) activity based on growth on minimal media containing (rac)-α-methylbenzylamine (rac-α-MBA) as a sole nitrogen source. Then, for the selection of strains with high enzyme activity, a colorimetric o-xylylendiamine assay was conducted. The most promising strains were identified by 16S rDNA sequencing. Five microorganisms showing high ω-TA activity were subjected to determine optimal conditions for ω-TA activity, including pH, temperature, co-solvent, and the specificity of the ω-TA toward different amine donors and acceptors. Among the five screened microorganisms, Bacillus halotolerans turned out to be the most promising strain: Its cell-free extract showed a highly versatile amino donor spectrum toward aliphatic, aromatic chiral amines and a broad range of pH activity. Transaminase activity also exhibited excellent solvent tolerance, with maximum turnover in the presence of 30% (v/v) DMSO.
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Dingman, Douglas W. "Conjugative transposition of Tn916 and Tn925 in Bacillus popilliae." Canadian Journal of Microbiology 45, no. 6 (July 15, 1999): 530–35. http://dx.doi.org/10.1139/w99-036.
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Interspecies transfer of the conjugative transposons Tn916 and Tn925 into B. popilliae Pj1 occurred using Enterococcus faecalis and Bacillus subtilis CU4049 as transposon donors. Tn916 was stably maintained in B. popilliae Pj1 following growth without selective pressure and was successfully introduced into the plasmid-containing B. popilliae strains NRRL B-2524, Ch1, and KLN4 using E. faecalis CG110. In B. popilliae, expression of the tetracycline resistant determinants on Tn916 and Tn925 provided resistance to 25 μg/mL and 50 μg/mL tetracycline, respectively. An erythromycin resistant determinant, present in Tn916ΔE, was also functional in B. popilliae Pj1 and provided resistance to 1 mg/mL erythromycin. Transfer of Tn916 into E. faecalis, B. subtilis, and between B. popilliae strains was accomplished using a transposon-containing strain of B. popilliae as donor. Efforts to transfer Tn916 between E. coli and B. popilliae were unsuccessful. Key words: Bacillus popilliae, milky disease, Tn916, conjugative transposon.
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Kim, Joo-Sung, Donna K. Carver, and Sophia Kathariou. "Natural Transformation-Mediated Transfer of Erythromycin Resistance in Campylobacter coli Strains from Turkeys and Swine." Applied and Environmental Microbiology 72, no. 2 (February 2006): 1316–21. http://dx.doi.org/10.1128/aem.72.2.1316-1321.2006.
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ABSTRACT Erythromycin resistance in Campylobacter coli from meat animals is frequently encountered and could represent a substantial barrier to antibiotic treatment of human infections. Erythromycin resistance in this organism has been associated with a point mutation (A2075G) in the 23S rRNA gene. However, the mechanisms responsible for possible dissemination of erythromycin resistance in C. coli remain poorly understood. In this study, we investigated transformation-mediated acquisition of erythromycin resistance by genotypically diverse C. coli strains from turkeys and swine, with total genomic DNA from erythromycin-resistant C. coli of either turkey or swine origin used as a donor. Overall, transformation to erythromycin resistance was significantly more frequent in C. coli strains from turkeys than in swine-derived strains (P < 0.01). The frequency of transformation to erythromycin resistance was 10−5 to 10−6 for turkey-derived strains but 10−7 or less for C. coli from swine. Transformants harbored the point mutation A2075G in the 23S rRNA gene, as did the erythromycin-resistant strains used as DNA donors. Erythromycin resistance was stable in transformants following serial transfers in the absence of the antibiotic, and most transformants had high MICs (>256 μg/ml), as did the C. coli donor strains. In contrast to the results obtained with transformation, spontaneous mutants had relatively low erythromycin MICs (32 to 64 μg/ml) and lacked the A2075G mutation in the 23S rRNA gene. These findings suggest that natural transformation has the potential to contribute to the dissemination of high-level resistance to erythromycin among C. coli strains colonizing meat animals.
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Hoffmann, Andrea, Torsten Thimm, Marcus Dröge, Edward R. B. Moore, Jean Charles Munch, and Christoph C. Tebbe. "Intergeneric Transfer of Conjugative and Mobilizable Plasmids Harbored by Escherichia coli in the Gut of the Soil Microarthropod Folsomia candida(Collembola)." Applied and Environmental Microbiology 64, no. 7 (July 1, 1998): 2652–59. http://dx.doi.org/10.1128/aem.64.7.2652-2659.1998.
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ABSTRACT The gut of the soil microarthropod Folsomia candidaprovides a habitat for a high density of bacterial cells (T. Thimm, A. Hoffmann, H. Borkott, J. C. Munch, and C. C. Tebbe, Appl. Environ. Microbiol. 64:2660–2669, 1998). We investigated whether these gut bacteria act as recipients for plasmids from Escherichia coli. Filter mating with E. coli donor cells and collected feces of F. candida revealed that the broad-host-range conjugative plasmid pRP4-luc (pRP4 with a luciferase marker gene) transferred to fecal bacteria at estimated frequencies of 5.4 × 10−1 transconjugants per donor. The mobilizable plasmid pSUP104-luc was transferred from the IncQ mobilizing strain E. coli S17-1 and less efficiently from the IncF1 mobilizing strain NM522 but not from the nonmobilizing strain HB101. When S17-1 donor strains were fed to F. candida, transconjugants of pRP4-luc and pSUP104-luc were isolated from feces. Additionally, the narrow-host-range plasmid pSUP202-luc was transferred to indigenous bacteria, which, however, could not maintain this plasmid. Inhibition experiments with nalidixic acid indicated that pRP4-luc plasmid transfer took place in the gut rather than in the feces. A remarkable diversity of transconjugants was isolated in this study: from a total of 264 transconjugants, 15 strains belonging to the alpha, beta, or gamma subclass of the class Proteobacteriawere identified by DNA sequencing of the PCR-amplified 16S rRNA genes and substrate utilization assays (Biolog). Except forAlcaligenes faecalis, which was identified by the Biolog assay, none of the isolates was identical to reference strains from data banks. This study indicates the importance of the microarthropod gut for enhanced conjugative gene transfer in soil microbial communities.
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Poinsot, Denis, Kostas Bourtzis, George Markakis, Charalambos Savakis, and Hervé Merçot. "Wolbachia Transfer from Drosophila melanogaster into D. simulans: Host Effect and Cytoplasmic Incompatibility Relationships." Genetics 150, no. 1 (September 1, 1998): 227–37. http://dx.doi.org/10.1093/genetics/150.1.227.
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Abstract Wolbachia are maternally transmitted endocellular bacteria causing a reproductive incompatibility called cytoplasmic incompatibility (CI) in several arthropod species, including Drosophila. CI results in embryonic mortality in incompatible crosses. The only bacterial strain known to infect Drosophila melanogaster (wDm) was transferred from a D. melanogaster isofemale line into uninfected D. simulans isofemale lines by embryo microinjections. Males from the resulting transinfected lines induce >98% embryonic mortality when crossed with uninfected D. simulans females. In contrast, males from the donor D. melanogaster line induce only 18–32% CI on average when crossed with uninfected D. melanogaster females. Transinfected D. simulans lines do not differ from the D. melanogaster donor line in the Wolbachia load found in the embryo or in the total bacterial load of young males. However, >80% of cysts are infected by Wolbachia in the testes of young transinfected males, whereas only 8% of cysts are infected in young males from the D. melanogaster donor isofemale line. This difference might be caused by physiological differences between hosts, but it might also involve tissue-specific control of Wolbachia density by D. melanogaster. The wDm-transinfected D. simulans lines are unidirectionally incompatible with strains infected by the non-CI expressor Wolbachia strains wKi, wMau, or wAu, and they are bidirectionally incompatible with strains infected by the CI-expressor Wolbachia strains wHa or wNo. However, wDm-infected males do not induce CI toward females infected by the CI-expressor strain wRi, which is found in D. simulans continental populations, while wRi-infected males induce partial CI toward wDm-infected females. This peculiar asymmetrical pattern could reflect an ongoing divergence between the CI mechanisms of wRi and wDm. It would also confirm other results indicating that the factor responsible for CI induction in males is distinct from the factor responsible for CI rescue in females.
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De Milander, C., M. S. E. Wimmers, J. V. Van der Merwe, and F. Le R. Fourie. "Successful transcervical embryo transfer in two strains of mice." Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 7, no. 1 (March 17, 1988): 26–27. http://dx.doi.org/10.4102/satnt.v7i1.895.
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Two strains of mice (a black Balb/C x C5 BL and a white NMRI strain) were stimulated to superovulate and allowed to copulate with males of a similar strain. Blastocysts were obtained from black donor animals after cervical dislocation and flushing of the fallopian tubes 3,5 days after copulation. A total of 460 blastocysts were flushed and 6 blastocysts were transfered to each of the 71 white surrogate individuals which had copulated 2,5 days previously. A total of 51 births were documented with a 31,4% occurrence of black phenotypic animals in the litter.
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Zverlov, Vladimir, Michael Klein, Sebastian Lücker, Michael W. Friedrich, Josef Kellermann, David A. Stahl, Alexander Loy, and Michael Wagner. "Lateral Gene Transfer of Dissimilatory (Bi)Sulfite Reductase Revisited." Journal of Bacteriology 187, no. 6 (March 15, 2005): 2203–8. http://dx.doi.org/10.1128/jb.187.6.2203-2208.2005.
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ABSTRACT In contrast to previous findings, we demonstrate that the dissimilatory (bi)sulfite reductase genes (dsrAB) of Desulfobacula toluolica were vertically inherited. Furthermore, Desulfobacterium anilini and strain mXyS1 were identified, by dsrAB sequencing of 17 reference strains, as members of the donor lineage for those gram-positive Desulfotomaculum species which laterally acquired dsrAB.
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Ben Fguira, Ines, Zaineb Fourati, Fakher Kamoun, Slim Tounsi, and Samir Jaoua. "Isolation of the Bacillus thuringiensis plasmid carrying Bacthuricin F4 coding genes and evidence of its conjugative transfer." Journal of Infection in Developing Countries 8, no. 06 (June 11, 2014): 727–32. http://dx.doi.org/10.3855/jidc.3552.
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Introduction: Conjugation is an excellent natural mode of DNA transfer in vivo between bacteria, particularly when these conjugative elements carry technological traits such as bacteriocin encoding genes. In the present work, the bacteriocinogenic plasmid pIBF4 from Bacillus thuringiensis responsible of Bacthuricin F4 synthesis was isolated and characterized. Methodology: To isolate pIBF4, the total plasmid DNA from a non-bacteriocin transposant carrying the mini-Tn10 spectinomycin selective marker was extracted and used to transform Escherichia coli strain Top10. PIBF4 was extracted from the obtained transformant and then subjected to restriction enzyme analysis. Plasmid curing experiments were conducted to test the stability of pIBF4 at a stringent temperature of 42°C. Conjugative behavior of pIBF4 was assessed by mating experiments using the non-bacteriocin transposant mutant as a donor strain and several Bacillus thuringiensis strains as recipients. Results: The pIBF4 plasmid was isolated and had a molecular weight of 19.1 kb. Ninety-five percent of cells retained the pIBF4 plasmid after 200 generations, demonstrating its high stability. PIBF4 was successfully transferred to Bacillus thuringiensis HD1CryB strain with a transfer frequency of 1x10-8 transconjugants per donor cell. The study of the recipient host range revealed that pIBF4 is specifically transferable to Bacillus thuringiensis strains with variable transfer frequencies depending on the recipient host strain. Conclusion: Our results show that pIBF4 is a 19.1 kb highly stable plasmid transferable by conjugation to Bacillus thuringiensis strains with deferent transfer frequencies.
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Sorokin, Dimitry Yu, Tatjana P. Tourova, Gesche Braker, and Gerard Muyzer. "Thiohalomonas denitrificans gen. nov., sp. nov. and Thiohalomonas nitratireducens sp. nov., novel obligately chemolithoautotrophic, moderately halophilic, thiodenitrifying Gammaproteobacteria from hypersaline habitats." International Journal of Systematic and Evolutionary Microbiology 57, no. 7 (July 1, 2007): 1582–89. http://dx.doi.org/10.1099/ijs.0.65112-0.
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A novel group of moderately halophilic, obligately chemolithoautotrophic, sulfur-oxidizing Gammaproteobacteria was found in sediments of various inland hypersaline lakes and a solar saltern. These bacteria were enriched and isolated with thiosulfate as electron donor and nitrate as electron acceptor at 2 M NaCl. Ten isolates (HLD strains) were long non-motile rods. They grew anaerobically as complete denitrifiers, and aerobically under micro-oxic conditions. Sulfate was the final product of thiosulfate and sulfide oxidation, and nitrite and N2O were intermediates of nitrate reduction to N2. The HLD strains grew optimally at pH 7.3–7.8, and at NaCl concentrations of 1.5–2.0 M. On the basis of phenotypic and genetic analysis, the moderately halophilic, thiodenitrifying isolates are proposed to be assigned to a new genus and species, Thiohalomonas denitrificans gen. nov., sp. nov. The type strain is HLD 2T (=DSM 15841T=UNIQEM U222T ). A single strain, HRhD 3spT, with vibrio-shaped cells, was obtained from a co-culture capable of complete denitrification of nitrate in the presence of either thiocyanate or thiosulfate as electron donor. It grew anaerobically with thiosulfate, reducing nitrate to nitrite, or under micro-oxic conditions at 1.0–2.5 M NaCl with an optimum at 1.0 M. Strain HRhD 3spT was genetically related to the HLD strains at the level of a separate species and is described as Thiohalomonas nitratireducens sp. nov. The type strain is HRhD 3spT (=DSM 16925T=UNIQEM U248T).
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Chou, Sunwen. "Acquisition of Donor Strains of Cytomegalovirus by Renal-Transplant Recipients." New England Journal of Medicine 314, no. 22 (May 29, 1986): 1418–23. http://dx.doi.org/10.1056/nejm198605293142205.
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Sanford, Robert A., James R. Cole, and James M. Tiedje. "Characterization and Description of Anaeromyxobacter dehalogenans gen. nov., sp. nov., an Aryl-Halorespiring Facultative Anaerobic Myxobacterium." Applied and Environmental Microbiology 68, no. 2 (February 2002): 893–900. http://dx.doi.org/10.1128/aem.68.2.893-900.2002.
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ABSTRACT Five strains were isolated which form a physiologically and phylogenetically coherent group of chlororespiring microorganisms and represent the first taxon in the Myxobacteria capable of anaerobic growth. The strains were enriched and isolated from various soils and sediments based on their ability to grow using acetate as an electron donor and 2-chlorophenol (2-CPh) as an electron acceptor. They are slender gram-negative rods with a bright red pigmentation that exhibit gliding motility and form spore-like structures. These unique chlororespiring myxobacteria also grow with 2,6-dichlorophenol, 2,5-dichlorophenol, 2-bromophenol, nitrate, fumarate, and oxygen as terminal electron acceptors, with optimal growth occurring at low concentrations (<1 mM) of electron acceptor. 2-CPh is reduced by all strains as an electron acceptor in preference to nitrate, which is reduced to ammonium. Acetate, H2, succinate, pyruvate, formate, and lactate were used as electron donors. None of the strains grew by fermentation. The 16S ribosomal DNA (rDNA) sequences of the five strains form a coherent cluster deeply branching within the family Myxococcaceae within the class Myxobacteria and are mostly closely associated with the Myxococcus subgroup. With the exception of anaerobic growth and lack of a characteristic fruiting body, these strains closely resemble previously characterized myxobacteria and therefore should be considered part of the Myxococcus subgroup. The anaerobic growth and 9.0% difference in 16S rDNA sequence from those of other myxobacterial genera are sufficient to place these strains in a new genus and species designated Anaeromyxobacter dehalogenans. The type strain is 2CP-1 (ATCC BAA-258).
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Pannekoek, Yvonne, Steven M. Westenberg, Jan de Vries, Sjoerd Repping, Lodewijk Spanjaard, Paul P. Eijk, Arie van der Ende, and Jacob Dankert. "PCR Assessment of Chlamydia trachomatisInfection of Semen Specimens Processed for Artificial Insemination." Journal of Clinical Microbiology 38, no. 10 (2000): 3763–67. http://dx.doi.org/10.1128/jcm.38.10.3763-3767.2000.
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In order to ascertain the microbiological quality of stored semen specimens processed for artificial insemination by a donor (AID), we developed a PCR assay targeting the chlamydial plasmid to detectChlamydia trachomatis in semen. The lower limit of detection of this assay corresponded to 2.5 to 5 elementary bodies per μl of semen. A total of 669 cryopreserved ejaculates from 97 asymptomatic donors were tested for C. trachomatisinfection. Twelve ejaculates, originating from four donors, were found to be positive, indicating a 4% prevalence of C. trachomatis infection among the donor population studied. Cross-contamination between the cryopreserved specimens in the storage container was studied by typing using sequence analysis of PCR-amplified omp1 genes of the strains. Two donors were infected with serovar E, one was infected with serovar F, and one was infected with serovar K. For two donors, the duration of C. trachomatis positivity could be assessed. One donor donatedC. trachomatis-positive semen for at least 4 successive months, and the other did so for at least 16 months. The occurrence ofC. trachomatis infection in cryopreserved donor semen indicates that ejaculates from donors not tested for a C. trachomatis infection just prior to donation should be tested for infection by a direct test such as the PCR described here. Direct testing of semen specimens will detect not only donors with an active infection but also C. trachomatis-infected ejaculates already stored and will thus improve the microbiological quality of AID, since discrepancies in the presence of C. trachomatisin urine and semen specimens have been reported.
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MURINDA, SHELTON E., SHU-MIN LIU, ROBERT F. ROBERTS, and RICHARD A. WILSON. "Colicinogeny among Escherichia coli Serotypes, Including O157:H7, Representing Four Closely Related Diarrheagenic Clones." Journal of Food Protection 61, no. 11 (November 1, 1998): 1431–38. http://dx.doi.org/10.4315/0362-028x-61.11.1431.
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Twenty-seven diarrheagenic Escherichia coli (DEC) strains from five closely related, genetically distinct clones (DEC 3, 4, 8, 9, and 10), representing serotypes commonly associated with Shiga-like toxin production, i.e., 015:H−, 026:(H11, H−), 0111:(H8, H11, H−), and O157:H7, were evaluated for colicinogeny on Luria agar or Luria agar containing 0.25 μg/ml mitomycin C to induce colicin production. Ten (37%) of the DEC strains tested were colicinogenic. One of 11 serotype O157:H7 strains, DEC strain 4E, produced a colicin identified as Col D. DEC strains 8B, 9D, and 10B produced Col E1, whereas DEC strain 10A produced Col E2. DEC strains 8A, 8E, 10C, 10E, and 10F produced “untypable” colicins that killed almost all Pugsley Colicin Reference Set strains and the other DEC strains tested. To aid with further characterization of the colicins, plasmids extracted from each colicin-producing (Col+) DEC strain were used to transform E. coli strain DH5α. All Col+ DH5α transformants contained one plasmid ranging in size from 1.3 to 10 kb. Some transformants were stable colicin producers whereas others were unstable. The inhibitory activity and colicin sensitivity and insensitivity profiles of the Col+ transformants were similar to those of the corresponding Col+ donor DEC strains. It appears that the untypable colicins are novel and, thus, warrant further study. Colicin production by some of the DEC strains evaluated partly explains why they were insensitive to standard colicins in a previous study.
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Machielsen, Ronnie, Roland J. Siezen, Sacha A. F. T. van Hijum, and Johan E. T. van Hylckama Vlieg. "Molecular Description and Industrial Potential of Tn6098Conjugative Transfer Conferring Alpha-Galactoside Metabolism inLactococcus lactis." Applied and Environmental Microbiology 77, no. 2 (November 29, 2010): 555–63. http://dx.doi.org/10.1128/aem.02283-10.
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ABSTRACTA novel 51-kb conjugative transposon ofLactococcus lactis, designated Tn6098, encoding the capacity to utilize α-galactosides such as raffinose and stachyose, was identified and characterized. Alpha-galactosides are a dominant carbon source in many plant-derived foods. Most dairy lactococcus strains are unable to use α-galactosides as a growth substrate, yet many of these strains are known to have beneficial industrial traits. Conjugal transfer of Tn6098was demonstrated from the plant-derived donor strainL. lactisKF147 to the recipientL. lactisNZ4501, a derivative of the dairy model strainL. lactisMG1363. The integration of Tn6098into the genome of the recipient strain was confirmed by Illumina sequencing of the transconjugantL. lactisNIZO3921. The molecular structure of the integration site was confirmed by a PCR product spanning the insertion site. A 15-bp direct repeat sequence (TTATACCATAATTAC) is present on either side of Tn6098in the chromosome ofL. lactisKF147. One copy of this sequence is also present in theL. lactisMG1363 chromosome and represents the sole integration site. Phenotypic characterization of all strains showed that the transconjugant has not only acquired the ability to grow well in soy milk, a substrate rich in α-galactosides, but also has retained the flavor-forming capabilities of the recipient strainL. lactisMG1363. This study demonstrates how (induced) conjugation can be used to exploit the beneficial industrial traits of industrial dairy lactic acid bacteria in fermentation of plant-derived substrates.
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Jin, Hong, Helen Zhou, Bin Lu, and George Kemble. "Imparting Temperature Sensitivity and Attenuation in Ferrets to A/Puerto Rico/8/34 Influenza Virus by Transferring the Genetic Signature for Temperature Sensitivity from Cold-Adapted A/Ann Arbor/6/60." Journal of Virology 78, no. 2 (January 15, 2004): 995–98. http://dx.doi.org/10.1128/jvi.78.2.995-998.2004.
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ABSTRACT The four temperature-sensitive (ts) loci identified in the PB1 and PB2 gene segments of cold-adapted A/Ann Arbor/6/60 influenza virus, the master donor virus for influenza A virus (MDV-A) FluMist vaccines, were introduced into a divergent A/Puerto Rico/8/34 influenza virus strain. Recombinant A/Puerto Rico/8/34 virus with these four introduced ts loci exhibited both ts and att phenotypes similar to those of MDV-A, which could be used as a donor virus for manufacturing large quantities of inactivated influenza virus vaccine against potential pandemic strains.
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Klink, Magdalena, Maciej Cedzyński, Anna St Świerzko, Henryk Tchórzewski, and Zofia Sulowska. "Involvement of nitric oxide donor compounds in the bactericidal activity of human neutrophils in vitro." Journal of Medical Microbiology 52, no. 4 (April 1, 2003): 303–8. http://dx.doi.org/10.1099/jmm.0.04974-0.
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The bactericidal activity of human neutrophils against extracellular and facultatively intracellular bacteria was studied in the presence of the nitric oxide (NO) donors sodium nitroprusside (SNP) and 3-morpholinosydnonimine (SIN-1), a molsidomine metabolite. SNP and molsidomine are drugs commonly used as nitrovasodilators in coronary heart disease. It is demonstrated here that the NO donor compounds themselves did not affect the viability and survival of the bacterial strains tested. Neither SNP nor SIN-1 had any effect on the process of bacteria ingestion. In contrast, NO donors enhanced the ability of neutrophils to kill Escherichia coli, Proteus vulgaris and Salmonella Anatum. However, strains differed in their susceptibility to SNP- and SIN-1-mediated killing by neutrophils. Removal of the superoxide anion reduced the bactericidal activity of SNP- and SIN-1-treated neutrophils against E. coli and S. Anatum. This suggests that the NO derivatives formed in the reaction of NO generated from donors with the reactive oxygen species released by phagocytosed neutrophils potentiate the bactericidal activity of human neutrophils in vitro. The above original observation discussed here suggests clinical significance for the treatment of patients with nitrovasodilators in the course of coronary heart disease therapy.
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Parshina, Sofiya N., Jan Sipma, Anne Meint Henstra, and Alfons J. M. Stams. "Carbon Monoxide as an Electron Donor for the Biological Reduction of Sulphate." International Journal of Microbiology 2010 (2010): 1–9. http://dx.doi.org/10.1155/2010/319527.
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Several strains of Gram-negative and Gram-positive sulphate-reducing bacteria (SRB) are able to use carbon monoxide (CO) as a carbon source and electron donor for biological sulphate reduction. These strains exhibit variable resistance to CO toxicity. The most resistant SRB can grow and use CO as an electron donor at concentrations up to 100%, whereas others are already severely inhibited at CO concentrations as low as 1-2%. Here, the utilization, inhibition characteristics, and enzymology of CO metabolism as well as the current state of genomics of CO-oxidizing SRB are reviewed. Carboxydotrophic sulphate-reducing bacteria can be applied for biological sulphate reduction with synthesis gas (a mixture of hydrogen and carbon monoxide) as an electron donor.
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Thon, G., and A. J. Klar. "Directionality of fission yeast mating-type interconversion is controlled by the location of the donor loci." Genetics 134, no. 4 (August 1, 1993): 1045–54. http://dx.doi.org/10.1093/genetics/134.4.1045.
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Abstract Cells of homothallic strains of Schizosaccharomyces pombe efficiently switch between two mating types called P and M. The phenotypic switches are due to conversion of the expressed mating-type locus (mat1) by two closely linked silent loci, mat2-P and mat3-M, that contain unexpressed information for the P and M mating types, respectively. In this process, switching-competent cells switch to the opposite mating type in 72-90% of the cell divisions. Hence, mat2-P is a preferred donor of information to mat1 in M cells, whereas mat3-M is a preferred donor in P cells. We investigated the reason for the donor preference by constructing a strain in which the genetic contents of the donor loci were swapped. We found that switching to the opposite mating type was very inefficient in that strain. This shows that the location of the silent cassettes in the chromosome, rather than their content, is the deciding factor for recognition of the donor for each cell type. We propose a model in which switching is achieved by regulating accessibility of the donor loci, perhaps by changing the chromatin structure in the mating-type region, thus promoting an intrachromosomal folding of mat2 or mat3 onto mat1 in a cell type-specific fashion. We also present evidence for the involvement of the Swi6 and Swi6-mod trans-acting factors in the donor-choice mechanism. We suggest that these factors participate in forming the proposed folded structure.
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Lesic, Biliana, and Elisabeth Carniel. "Horizontal Transfer of the High-Pathogenicity Island of Yersinia pseudotuberculosis." Journal of Bacteriology 187, no. 10 (May 15, 2005): 3352–58. http://dx.doi.org/10.1128/jb.187.10.3352-3358.2005.
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ABSTRACT The horizontal transfer of genetic elements plays a major role in bacterial evolution. The high-pathogenicity island (HPI), which codes for an iron uptake system, is present and highly conserved in various Enterobacteriaceae, suggesting its recent acquisition by lateral gene transfer. The aim of this work was to determine whether the HPI has kept its ability to be transmitted horizontally. We demonstrate here that the HPI is indeed transferable from a donor to a recipient Yersinia pseudotuberculosis strain. This transfer was observable only when the donor and recipient bacteria were cocultured at low temperatures in a liquid medium. When optimized conditions were used (bacteria actively growing in an iron-deprived medium at 4°C), the frequency of HPI transfer reached ∼10−8. The island was transferable to various serotype I strains of Y. pseudotuberculosis and to Yersinia pestis, but not to Y. pseudotuberculosis strains of serotypes II and IV or to Yersinia enterocolitica. Upon transfer, the HPI was inserted almost systematically into the asn3 tRNA locus. Acquisition of the HPI resulted in the loss of the resident island, suggesting an incompatibility between two copies of the HPI within the same strain. Transfer of the island did not require a functional HPI-borne insertion-excision machinery and was RecA dependent in the recipient but not the donor strain, suggesting that integration of the island into the recipient chromosome occurs via a mechanism of homologous recombination. This lateral transfer also involved the HPI-adjacent sequences, leading to the mobilization of a chromosomal region at least 46 kb in size.
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Milkman, Roger, Elisabeth A. Raleigh, Melissa McKane, Diane Cryderman, Patricia Bilodeau, and Kerri McWeeny. "Molecular Evolution of the Escherichia coli Chromosome. V. Recombination Patterns Among Strains of Diverse Origin." Genetics 153, no. 2 (October 1, 1999): 539–54. http://dx.doi.org/10.1093/genetics/153.2.539.
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Abstract Incorporation patterns of donor DNA into recipient chromosomes following transduction or conjugation have been studied in the progeny of a variety of Escherichia coli crosses in which donor and recipient nucleotide sequences differ by 1-3%. Series of contiguous or variously spaced PCR fragments have been amplified from each recombinant chromosome and digested with a commercial restriction endonuclease previously shown to distinguish the respective parents in a given fragment. We conclude that entering donor DNA fragments are frequently abridged (cut and shortened) before incorporation, the cutting being due to restriction systems, and the shortening presumably due to exonuclease activity. Analysis of several backcrosses confirms, and extends to conjugation, the importance of restriction in E. coli recombination in nature. The transmission patterns in conjugation are similar to those of transduction, but (as expected) on a much larger scale. Asymmetric results of reciprocal crosses imply that mismatch frequency is not a major factor. Marked differences among the results of simple crosses according to parental strain combinations are consistent with observations that E. coli strains in nature vary dramatically in their restriction-modification systems.
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López-López, María José, Begonya Vicedo, Natividad Orellana, Jaime Piquer, and María M. López. "Behavior of a Virulent Strain Derived from Agrobacterium radiobacter Strain K84 After Spontaneous Ti Plasmid Acquisition." Phytopathology® 89, no. 4 (April 1999): 286–92. http://dx.doi.org/10.1094/phyto.1999.89.4.286.
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The behavior of the virulent transconjugant K84N6 derived from Agrobacterium radiobacter strain K84 after spontaneous Ti plasmid transfer in crown gall tissue in a biocontrol experiment was studied and compared with the behavior of the wild-type A. tumefaciens donor of the Ti plasmid. The main difference between the strains was a greatly reduced ability of the transconjugant to catabolize nopaline. Host range, ability to induce tumors in several fruit trees, and stability of the pathogenic determinants in isolates from tumors did not differ between the strains. Nevertheless, in a biocontrol experiment, the transconjugant was not controlled by strain K84 or K1026 in peach × almond hybrids and survived in the plant rhizo-sphere for 9 months with larger population densities than the wild strain. The appearance and persistence in soil of strains harboring a Ti plasmid in the K84 chromosomal background could represent a risk in the medium term, if they show good competitive ability.
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Sawada, Akihisa, Deborah Croom-Carter, Osamu Kondo, Masahiro Yasui, Maho Koyama-Sato, Masami Inoue, Keisei Kawa, Alan B. Rickinson, and Rosemary J. Tierney. "Epstein–Barr virus latent gene sequences as geographical markers of viral origin: unique EBNA3 gene signatures identify Japanese viruses as distinct members of the Asian virus family." Journal of General Virology 92, no. 5 (May 1, 2011): 1032–43. http://dx.doi.org/10.1099/vir.0.030023-0.
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Polymorphisms in Epstein–Barr virus (EBV) latent genes can identify virus strains from different human populations and individual strains within a population. An Asian EBV signature has been defined almost exclusively from Chinese viruses, with little information from other Asian countries. Here we sequenced polymorphic regions of the EBNA1, 2, 3A, 3B, 3C and LMP1 genes of 31 Japanese strains from control donors and EBV-associated T/NK-cell lymphoproliferative disease (T/NK-LPD) patients. Though identical to Chinese strains in their dominant EBNA1 and LMP1 alleles, Japanese viruses were subtly different at other loci. Thus, while Chinese viruses mainly fall into two families with strongly linked ‘Wu’ or ‘Li’ alleles at EBNA2 and EBNA3A/B/C, Japanese viruses all have the consensus Wu EBNA2 allele but fall into two families at EBNA3A/B/C. One family has variant Li-like sequences at EBNA3A and 3B and the consensus Li sequence at EBNA3C; the other family has variant Wu-like sequences at EBNA3A, variants of a low frequency Chinese allele ‘Sp’ at EBNA3B and a consensus Sp sequence at EBNA3C. Thus, EBNA3A/B/C allelotypes clearly distinguish Japanese from Chinese strains. Interestingly, most Japanese viruses also lack those immune-escape mutations in the HLA-A11 epitope-encoding region of EBNA3B that are so characteristic of viruses from the highly A11-positive Chinese population. Control donor-derived and T/NK-LPD-derived strains were similarly distributed across allelotypes and, by using allelic polymorphisms to track virus strains in patients pre- and post-haematopoietic stem-cell transplant, we show that a single strain can induce both T/NK-LPD and B-cell-lymphoproliferative disease in the same patient.
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ZHANG, GUODONG, LI MA, and MICHAEL P. DOYLE. "Potential Competitive Exclusion Bacteria from Poultry Inhibitory to Campylobacter jejuni and Salmonella." Journal of Food Protection 70, no. 4 (April 1, 2007): 867–73. http://dx.doi.org/10.4315/0362-028x-70.4.867.
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The objective of this study was to isolate from chickens potential competitive exclusion bacteria (CE) that are inhibitory to Campylobacter jejuni or Salmonella, or to both, for subsequent development of a defined CE product for use in poultry. Adult chickens from family farms, commercial farms, and broiler chicken research centers were sampled to identify and select C. jejuni–free donor chickens. A challenge treatment, which included administering perorally 106 CFU C. jejuni per chicken and determining undetectable cecal shedding of campylobacters at 4 weeks, was important for identifying the best CE donor chickens. Screening of bacterial colonies obtained from nine donor chickens by using selective and nonselective media yielded 636 isolates inhibitory to six C. jejuni strains in vitro, with 194 isolates being strongly inhibitory. Of the 194 isolates, 145 were from ceca, and 117 were facultative anaerobic bacteria. One hundred forty-three isolates were inhibitory to six strains of Salmonella (including five different serotypes) in vitro. Of these, 41 were strongly inhibitory to all C. jejuni and Salmonella strains evaluated, and most were Lactobacillus salivarius. A direct overlay method, which involved directly applying soft agar on plates with discrete colonies from mucus scrapings of gastrointestinal tracts, was more effective in isolating CE than was the frequently practiced isolation method of picking and transferring discrete colonies and then overlaying them with soft agar. The best approach for obtaining bacteria highly inhibitory to Salmonella and C. jejuni from chickens was to isolate bacteria from ceca under anaerobic conditions. Free-range chickens from family farms were better donors of potential CE strongly inhibitory to both Salmonella and Campylobacter than were chickens from commercial farms and broiler chicken research centers.
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Pimentel, Muriel M. L., Fernanda A. Santos, Ana C. G. Teixeira, Roberta G. Izzo, Mikael A. Lima, Michelly F. Macedo, and Marcelo B. Bezerra. "Biochemical, thermographic, and follicular responses of murine models of hormone-treated bovine ovarian renal capsule xenografts." Pesquisa Veterinária Brasileira 37, no. 5 (May 2017): 425–31. http://dx.doi.org/10.1590/s0100-736x2017000500001.
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ABSTRACT: This study aimed to evaluate the characteristics of two different murine models of hormone-treated renal-encapsulated bovine ovarian tissue xenotransplantation. Two immunodeficient mouse models (BALB/c Nude and C57BL6 SCID) were xenografted with ovarian pieces from heifers and each group was subjected to two hormonal treatments of eCG or a combination of FSH+LH. Donor ovaries and recipients were evaluated by histology and infrared thermography at different times. At the time of xenograft collection, animals were evaluated for alterations in hepatorenal biochemistry. The statistical test used in the study was ANOVA, followed by Tukey’s test. Among the strains, 80% of C57BL6 SCID and 77% of BALB/c Nude mice showed development and vascularization of the transplanted tissue, which acquired cyclicity at 19 and 9 days post-transplant, respectively. Hemorrhagic follicles in xenografts induced with FSH+LH were found in the C57BL6 SCID strain. Infrared thermography was insufficient to distinguish the tissue donor recipient. In conclusion, the C57BL6 SCID strain appears to be the best host for ovarian xenografts, since the transplants in these mice were viable and showed robust follicular development. This work will aid future choices of immunodeficient strains for xenografting procedures.
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Negrin, Cervantes D., Delyth Graham, James S. Clark, Martin W. McBride, Fiona J. Carr, Niall H. Anderson, and Anna F. Dominiczak. "Chromosome 2 Reciprocal Congenics to Evaluate the Effect of the Genetic Background on Blood Pressure." Hypertension 36, suppl_1 (October 2000): 687. http://dx.doi.org/10.1161/hyp.36.suppl_1.687-c.
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54 Background Localisation of QTL using a genome wide scan strategy is the first step towards gene identification. This is followed by the construction of congenics by which the existence of the QTL can be verified. Congenic strains for chromosome 2 using the Dahl S as the recipient and WKY and MNS as donors, showed variable blood pressure (BP) depending on the donor alleles 1 . Methods We used a speed congenic approach to produce several congenic strains of chromosome 2 using the SHRSP Gla and the WKY Gla as recipients to test the effect of the genetic background of a given congenic on BP. In some strains, the region introgressed was identical to avoid confounding effects of additional QTLs. Two reciprocal control congenic strains were also produced to determine the presence of any passenger loci. Baseline systolic BP was measured by radiotelemetry. Results Four congenic and 2 parental strains were phenotyped (n=3-6). Transfer of the region of rat chromosome 2 from the WKY into a SHRSP background significantly lowered both day and night-time systolic BP by approximately 16 and 20 mm Hg respectively in male congenic rats compared to the SHRSP parental strains (p<0.005, 95%CI: 8.6-21.0 mm Hg; and p<0.005, 95%CI: 16.7-24.7 mm Hg). In contrast, transfer of the same region from the SHRSP into a WKY background significantly increased both day and night-time systolic BP by approximately 25 and 28 mm Hg, respectively in male congenic rats compared to the WKY parental strains (p<0.05, 95%CI: -49.2-2.0 mmHg; and p<0.05%, 95%CI: -61.2-6.1 mm Hg, respectively). Reciprocal control congenic strain showed no deviation from the BP recorded in the parental strain (Strain WKY.SPGla2b vs. WKY parental strain, 128.8±5.2 mm Hg vs. 139.7±5.7 mm Hg, p= ns; and strain SP.WKYGla2b vs. SHRSP parental strain, 178.0±5.0 mm Hg vs. 179.9±2.1 mm Hg, p= ns). Conclusions The results show the effect of a permissive background on BP and confirm that the genetic background chosen for a congenic strain has a significant effect on the BP phenotype. Moreover, this work sheds new light on the different epistatic or pleiotropic effects according to the genetic background chosen. 1. Deng AY et al . Hypertension 1997;30:199-202