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1.
J Dairy Sci ; 101(9): 7808-7811, 2018 Sep.
Article in English | MEDLINE | ID: mdl-29935831

ABSTRACT

The AmpC enzyme is normally expressed constitutively in Escherichia coli, and its overproduction confers resistance to cefoxitin. A newly reported AmpC, the extended-spectrum AmpC (ESAC), is related to resistance to cefepime, a fourth-generation cephalosporin. This enzyme presents more flexibility in the active site due to insertions, replacements, and deletions on AA sequences. Many isolates producing ESAC were reported in human clinical isolates, but E. coli ESAC producers were reported in animals only in France. The animal E. coli strains can produce this enzyme and possibly disseminate it to human and production environments. In our study, 3 strains of E. coli from milk and feces bovine samples, collected in Rio de Janeiro, Brazil, were suspected to produce ESAC. After excluding other mechanisms of resistance, the gene was sequenced to verify ESAC characteristics. These strains presented replacement of AA in omega and R2 loops, suggesting ESAC production. This is the first report to study ESAC E. coli in dairy farms in Brazil.


Subject(s)
Drug Resistance, Bacterial , Escherichia coli/enzymology , Feces/microbiology , Milk/microbiology , Animals , Bacterial Proteins , Brazil , Cattle , Escherichia coli/isolation & purification , Escherichia coli Infections , Farms , Humans , Microbial Sensitivity Tests , beta-Lactamases
2.
Cryo Letters ; 39(1): 67-71, 2018.
Article in English | MEDLINE | ID: mdl-29734417

ABSTRACT

BACKGROUND: Semen cryopreservation causes DNA damage, thus requiring continuous monitoring. OBJECTIVE: To compare two assays for sperm DNA fragmentation (SDF) from stallions with contrasting semen freezability. MATERIALS AND METHODS: Thirteen stallions were classified as good semen freezers (GSF) or bad semen freezers (BSF). Ejaculates were cryopreserved with three diluents. Semen was subject to SDF evaluation using the sperm chromatin structure assay (SCSA) and Halomax after thawing (0 h) and after a 4 h thermoresistance test. RESULTS: On semen of BSF, analysis by SCSA was similar between evaluations, but Halomax showed increased SDF at 4 h. The GSF group was similar between time points in both assays. Diluents did not affect SDF, irrespective of the assay. Halomax showed differences for BSF between time points, differently from SCSA. Linear regression did not show any correlation between assays. CONCLUSION: The use of Halomax should be encouraged for sperm DNA fragmentation analysis in horse frozen-thawed semen, particularly under field conditions.


Subject(s)
Biological Assay/methods , Cryopreservation/veterinary , DNA Fragmentation , Horses/physiology , Semen Preservation/veterinary , Semen/metabolism , Spermatozoa/metabolism , Animals , Chromatin/metabolism , DNA Damage , Male , Semen Analysis/veterinary , Sperm Motility/physiology
3.
Bull Entomol Res ; 104(1): 88-96, 2014 Feb.
Article in English | MEDLINE | ID: mdl-24229507

ABSTRACT

Plutella xylostella (L.) is the most important pest of Brassicaceae worldwide, with a recent estimate of US$ 4-5 billion expenditure for the control of this insect. A case of very high resistance of this pest to chlorantraniliprole was recently associated with reduced efficacy in a Brazilian field of Brassica spp. Although diamide resistance has been characterized, the fitness of insects due to such resistance has yet to be examined. Therefore, in this study, biological parameters were assessed in both susceptible and resistant strains of P. xylostella subjected to sublethal chlorantraniliprole concentrations. The field strain showed high resistance to chlorantraniliprole (RR50=27,793-fold), although resistance rapidly decreased in the first generations, showing instability. The exposure of susceptible and resistant larvae to their respective LC1, LC10, and LC25 values led to an increased duration of the larval and pupae phases and reduced weight in both strains; however, no significant differences in pupal viability across the treatments were observed. The resistant insects presented significantly lower larval weight and fecundity and higher larval and pupal periods, hatchability, and male longevity when not exposed to chlorantraniliprole, suggesting a fitness cost associated with resistance. In addition, resistant females showed a significantly higher egg-laying period and longevity at LC25, whereas the males lived longer at LC1. Chlorantraniliprole negatively impacted the biological parameters of both strains tested, although these effects were more relevant to the resistant insects. Resistant P. xylostella showed negative and positive biological trade-offs when compared with the susceptible individuals in both the absence and presence of chlorantraniliprole. Despite the important role that these trade-offs may play in the evolution of resistance to chlorantraniliprole, practical applications still depend on such information as the dominance of fitness costs and resistance.


Subject(s)
Brassicaceae/parasitology , Genetic Fitness/physiology , Insecticides/toxicity , Moths/growth & development , ortho-Aminobenzoates/toxicity , Animals , Brazil , Female , Fertility/drug effects , Genetic Fitness/drug effects , Insecticide Resistance/genetics , Kaplan-Meier Estimate , Larva/drug effects , Larva/growth & development , Male , Moths/drug effects
4.
Anim Reprod Sci ; 114(1-3): 203-9, 2009 Aug.
Article in English | MEDLINE | ID: mdl-18930362

ABSTRACT

This study examined the effect of treating mares with equine pituitary extract (EPE) alone or in combination with hCG on the recovery rate of immature follicles by transvaginal follicular aspiration (ovum pick-up; OPU). Ten normally cycling crossbred mares aged 3-15 years and weighing 350-400 kg were subjected to each of three treatments in a random sequence with each exposure to a new treatment separated by a rest cycle during which a spontaneous ovulation occurred. The treatments were (1) superovulated with 25mg EPE and treated with 2500 IU hCG, (2) superovulation with 25mg EPE, and (3) control (no exogenous treatment). Treatments 7 days after spontaneous ovulation; and all the follicles >10mm were aspirated 24h after the largest follicle achieved a diameter of 27-30 mm for control group, and most follicles reached 22-27 mm for the EPE alone treatment. To the group EPE+hCG, when the follicles reached 22-27 mm, hCG was administered, 24h before OPU. Superovulation increased the number of follicles available for aspiration. The total number of follicles available for aspiration was 61 in the EPE/hCG group, 63 in the EPE group and 42 in the control. The proportion of follicles aspirated varied from 63.5% to 73.8%. Oocyte recovery rate ranged from 15.0% to 16.7% and the proportion of mares that yielded at least one oocyte was 70% (7/10) in the EPE/hCG, 60% (6/10) in the EPE alone and 50% (5/10) in control group. The EPE/hCG treatment had a higher proportion of follicles with expanded granulose cells (64.4%) than the control (3.3%; p<0.05) and the EPE treatment (25.0%). The intervals from spontaneous ovulation to aspiration were similar for all treatments (11-12 days). However, superovulatory treatment significantly increased the aspiration to ovulation interval from 15+/-4 days for control to 27+/-15 days for EPE (p<0.05) and to 23+/-13 days for EPE/hCG treatment with commensurate increases in the time between spontaneous ovulations.


Subject(s)
Chorionic Gonadotropin/pharmacology , Oocytes/physiology , Ovarian Follicle/drug effects , Pituitary Gland/physiology , Tissue Extracts/pharmacology , Animals , Chorionic Gonadotropin/administration & dosage , Cross-Over Studies , Drug Therapy, Combination , Female , Horses , Ovulation , Tissue Extracts/administration & dosage , Tissue and Organ Harvesting/methods , Tissue and Organ Harvesting/veterinary
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