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Roberts M.C.,University of Washington | Schwarz S.,Institute of Farm Animal Genetics
Journal of Environmental Quality | Year: 2016

Recent reports have speculated on the future impact that antibiotic-resistant bacteria will have on food production, human health, and global economics. This review examines microbial resistance to tetracyclines and phenicols, antibiotics that are widely used in global food production. The mechanisms of resistance, mode of spread between agriculturally and humanimpacted environments and ecosystems, distribution among bacteria, and the genes most likely to be associated with agricultural and environmental settings are included. Forty-six different tetracycline resistance (tet) genes have been identified in 126 genera, with tet(M) having the broadest taxonomic distribution among all bacteria and tet(B) having the broadest coverage among the Gram-negative genera. Phenicol resistance genes are organized into 37 groups and have been identified in 70 bacterial genera. The review provides the latest information on tetracycline and phenicol resistance genes, including their association with mobile genetic elements in bacteria of environmental, medical, and veterinary relevance. Knowing what specific antibiotic-resistance genes (ARGs) are found in specific bacterial species and/or genera is critical when using a selective suite of ARGs for detection or surveillance studies. As detection methods move to molecular techniques, our knowledge about which type of bacteria carry which resistance gene(s) will become more important to ensure that the whole spectrum of bacteria are included in future surveillance studies. This review provides information needed to integrate the biology, taxonomy, and ecology of tetracycline- and phenicol-resistant bacteria and their resistance genes so that informative surveillance strategies can be developed and the correct genes selected. © American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. Source


Hall R.M.,University of Sydney | Schwarz S.,Institute of Farm Animal Genetics
Journal of Antimicrobial Chemotherapy | Year: 2016

In the genomic era, studying the epidemiology of individual antibiotic resistance genes and resistance gene discovery are open to all. However, the identification and naming of resistance genes is not currently understandable by all owing to a plethora of competing nomenclature systems, many of which do not comply with the basic rules of bacterial gene nomenclature. Change is needed urgently. Here, we make a case for the resistance research community to begin this process by agreeing on an answer to the question of when a new gene number should be assigned. This cut-off is of necessity arbitrary and we suggest a threshold value of ≥2% difference in the sequences of the DNA, predicted protein or both as a realistic boundary for assigning a new gene number. This proposal can be a starting point for agreement or debate followed by renumbering of the affected gene families. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. Source


Urrego R.,University of Antioquia | Urrego R.,CES University | Rodriguez-Osorio N.,University of Antioquia | Niemann H.,Institute of Farm Animal Genetics
Epigenetics | Year: 2014

The use of Assisted Reproductive Technologies (ARTs) in modern cattle breeding is an important tool for improving the production of dairy and beef cattle. A frequently employed ART in the cattle industry is in vitro production of embryos. However, bovine in vitro produced embryos differ greatly from their in vivo produced counterparts in many facets, including developmental competence. The lower developmental capacity of these embryos could be due to the stress to which the gametes and/or embryos are exposed during in vitro embryo production, specifically ovarian hormonal stimulation, follicular aspiration, oocyte in vitro maturation in hormone supplemented medium, sperm handling, gamete cryopreservation, and culture of embryos. The negative effects of some ARTs on embryo development could, at least partially, be explained by disruption of the physiological epigenetic profile of the gametes and/or embryos. Here, we review the current literature with regard to the putative link between ARTs used in bovine reproduction and epigenetic disorders and changes in the expression profile of embryonic genes. Information on the relationship between reproductive biotechnologies and epigenetic disorders and aberrant gene expression in bovine embryos is limited and novel approaches are needed to explore ways in which ARTs can be improved to avoid epigenetic disorders. © 2014 Landes Bioscience. Source


Nowak-Imialek M.,Institute of Farm Animal Genetics | Niemann H.,Institute of Farm Animal Genetics
Reproduction, Fertility and Development | Year: 2013

Pluripotent cells, such as embryonic stem (ES) cells, embryonic germ cells and embryonic carcinoma cells are a unique type of cell because they remain undifferentiated indefinitely in in vitro culture, show self-renewal and possess the ability to differentiate into derivatives of the three germ layers. These capabilities make them a unique in vitro model for studying development, differentiation and for targeted modification of the genome. True pluripotent ESCs have only been described in the laboratory mouse and rat. However, rodent physiology and anatomy differ substantially from that of humans, detracting from the value of the rodent model for studies of human diseases and the development of cellular therapies in regenerative medicine. Recently, progress in the isolation of pluripotent cells in farm animals has been made and new technologies for reprogramming of somatic cells into a pluripotent state have been developed. Prior to clinical application of therapeutic cells differentiated from pluripotent stem cells in human patients, their survival and the absence of tumourigenic potential must be assessed in suitable preclinical large animal models. The establishment of pluripotent cell lines in farm animals may provide new opportunities for the production of transgenic animals, would facilitate development and validation of large animal models for evaluating ESC-based therapies and would thus contribute to the improvement of human and animal health. This review summarises the recent progress in the derivation of pluripotent and reprogrammed cells from farm animals. We refer to our recent review on this area, to which this article is complementary. © 2013 IETS. Source


Kadlec K.,Institute of Farm Animal Genetics | Schwarz S.,Institute of Farm Animal Genetics
Antimicrobial Agents and Chemotherapy | Year: 2010

The trimethoprim resistance gene dfrK was found to be part of the novel Tn554-related transposon Tn559 integrated in the chromosomal radC gene of a porcine methicillin-susceptible Staphylococcus aureus ST398 strain. While Tn559 and Tn554 had similar arrangements of the transposase genes tnpA, tnpB, and tnpC, the Tn554-associated resistance genes erm(A) and spc were replaced by dfrK in Tn559. Circular forms of Tn559 were detected and suggest the functional activity of this transposon. Copyright © 2010, American Society for Microbiology. All Rights Reserved. Source

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