Jiangsu Lihua Animal Husbandry CO.
Jiangsu Lihua Animal Husbandry CO.
Wang J.,South China Agricultural University |
Guo Z.-W.,South China Agricultural University |
Zhi C.-P.,South China Agricultural University |
Yang T.,South China Agricultural University |
And 10 more authors.
Journal of Antimicrobial Chemotherapy | Year: 2017
Objectives: To investigate the impact of plasmid-borne oqxAB genes on the development of fluoroquinolone resistance, mutations and bacterial fitness in Escherichia coli. Methods: MICs andmutation prevention concentrations were compared among E. coli strain TOP10 and two corresponding transformants harbouring the OqxAB-encoding plasmids. Mutants were selected by serial passages with the 0.5-fold MIC of ciprofloxacin, and were randomly selected to determine mutations. Bacterial fitness was evaluated by competition assays in vitro and in vivo. Results: The oqxAB-carrying plasmids contributed to a 4-8-fold increase in the ciprofloxacin MIC and increased the ciprofloxacin mutation prevention concentration by 8-16-fold. The MIC of ciprofloxacin for the two transformants increased faster than that of E. coli TOP10 by serial passaging. Novel mutations in gyrB (A468P or F458V) were first observed. Mutations in gyrA were distributed at codons 87 and 83 in the two transformants, whereas mutation A119E in gyrA dominated in the TOP10 mutants. Although the two oqxAB-bearing plasmids caused a decrease in fitness in vitro, their fitness increased when combined with more than one chromosomal mutation, and clear biological benefits were observed in vivo. The mutations in gyrB were associated with a fitness cost, which could be compensated for by additional mutations. The novel mutation gyrA ΔS83 significantly reduced biological fitness both in vitro and in vivo, and was thus quickly replaced by more beneficial mutations in the population. Conclusions: The possession of plasmid-borne oqxAB may facilitate the evolution of fluoroquinolone resistance, and the fitness cost of OqxAB-encoding plasmids could be compensated by additional chromosomalmutations. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.
Yu S.G.,Nanjing Agricultural University |
Chu W.W.,Nanjing Agricultural University |
Zhang L.F.,Nanjing Agricultural University |
Han H.M.,Jiangsu Lihua Animal Husbandry CO. |
And 7 more authors.
PLoS ONE | Year: 2015
Laying performance is an important economical trait of goose production. As laying performance is of low heritability, it is of significance to develop a marker-assisted selection (MAS) strategy for this trait. Definition of sequence variation related to the target trait is a prerequisite of quantitating MAS, but little is presently known about the goose genome, which greatly hinders the identification of genetic markers for the laying traits of geese. Recently developed restriction site-associated DNA (RAD) sequencing is a possible approach for discerning large-scale single nucleotide polymorphism (SNP) and reducing the complexity of a genome without having reference genomic information available. In the present study, we developed a pooled RAD sequencing strategy for detecting geese layingrelated SNP. Two DNA pools were constructed, each consisting of equal amounts of genomic DNA from 10 individuals with either high estimated breeding value (HEBV) or low estimated breeding value (LEBV). A total of 139,013 SNP were obtained from 42,291,356 sequences, of which 18,771,943 were for LEBV and 23,519,413 were for HEBV cohorts. Fifty-five SNP which had different allelic frequencies in the two DNA pools were further validated by individual-based AS-PCR genotyping in the LEBV and HEBV cohorts. Ten out of 55 SNP exhibited distinct allele distributions in these two cohorts. These 10 SNP were further genotyped in a goose population of 492 geese to verify the association with egg numbers. The result showed that 8 of 10 SNP were associated with egg numbers. Additionally, liner regression analysis revealed that SNP Record-111407, 106975 and 112359 were involved in a multiplegene network affecting laying performance. We used IPCR to extend the unknown regions flanking the candidate RAD tags. The obtained sequences were subjected to BLAST to retrieve the orthologous genes in either ducks or chickens. Five novel genes were cloned for geese which harbored the candidate laying-related SNP, including membrane associated guanylate kinase (MAGI-1), KIAA1462, Rho GTPase activating protein 21 (ARHGAP21), acyl-CoA synthetase family member 2 (ACSF2), astrotactin 2 (ASTN2). Collectively, our data suggests that 8 SNP and 5 genes might be promising candidate markers or targets for marker-assisted selection of egg numbers in geese.