Spontaneous rate of sister chromatid exchanges (SCEs) and BrdU dose-response relationships in mitotic chromosomes of goat (Capra hircus L.).

The spontaneous level of sister chromatid exchange (SCEs) in the goat, estimated by exposing peripheral blood lymphocytes to 0.1 pg/ml of 5-bromodeoxyuridine (BrdU), was 3.28 k 1.71 SCE/cell, 1.64 SCE/cell generation and 0.027 SCE/chromosome. The dose-response curve of SCE/cell, observed by exposing the cells to 0.1, 0.25, 0.5, 1.0, 2.5, and 5.0 pg/ml of BrdU, rose rapidly from 0.1 to 0.5 pg/ml, remained fairly stable from 0.5 to 1.0 pg/ml and rose less rapidly from 1.0 to 5.0 pg/ml of BrdU. The frequency distribution of sister chromatid exchanges/cell and that of chromosomes showing various number of exchanges followed the Poisson probability at all BrdU levels; only at 5.0 pg/ml of BrdU was the fit found on the border of the 5 % probability level. The usefulness of determining the spontaneous level of SCE/cell in domestic animals is discussed in relation to its possible application for a more precise evaluation of the genotoxic effects of environmental pollutants. Din0 Di Berurdino, Departmeni of Animal Science, Via Universira 133, 80055 Portici-Napoli, ital

Whole genome sequencing for genomics-guided investigations of Escherichia coli O157:H7 outbreaks

Multi isolate whole genome sequencing (WGS) and typing for outbreak investigations has become a reality in the post-genomics era. We applied this technology to strains from Escherichia coli O157:H7 outbreaks. These include isolates from seven North America outbreaks, as well as multiple isolates from the same patient and from different infected individuals in the same household. Customized high-resolution bioinformatics sequence typing strategies were developed to assess the core genome and mobilome plasticity. Sequence typing was performed using an in-house single nucleotide polymorphism (SNP) discovery and validation pipeline. Discriminatory power becomes of particular importance for the investigation of isolates from outbreaks in which macrogenomic techniques such as pulse-field gel electrophoresis or multiple locus variable number tandem repeat analysis do not differentiate closely related organisms. We also characterized differences in the phage inventory, allowing us to identify plasticity among outbreak strains that is not detectable at the core genome level. Our comprehensive analysis of the mobilome identified multiple plasmids that have not previously been associated with this lineage. Applied phylogenomics approaches provide strong molecular evidence for exceptionally little heterogeneity of strains within outbreaks and demonstrate the value of intra-cluster comparisons, rather than basing the analysis on archetypal reference strains. Next generation sequencing and whole genome typing strategies provide the technological foundation for genomic epidemiology outbreak investigation utilizing its significantly higher sample throughput, cost efficiency, and phylogenetic relatedness accuracy. These phylogenomics approaches have major public health relevance in translating information from the sequence-based survey to support timely and informed countermeasures. Polymorphisms identified in this work offer robust phylogenetic signals that index both short- and long-term evolution and can complement currently employed typing schemes for outbreak ex- and inclusion, diagnostics, surveillance, and forensic studies

Spontaneous rate of sister chromatid exchanges (SCEs) in mitotic chromosomes of sheep (Ovis aries L.) and comparison with cattle (Bos taurus L.), goat (Capra hircus L.) and river buffalo (Bubalus bubalis L.).

The spontaneous level of sister chromatid exchanges (SCEs) in the sheep, estimated by exposing peripheral blood lymphocytes in 0.1 microgram/ml of 5'-bromodeoxyuridine (BrdU), was 4.08 +/- 2.47 SCE/cell, 2.04 SCE/cell cycle, 0.038 SCE/chromosome. The dose-response relationships, observed by exposing the cells to 0.1, 0.25, 0.5, 1.0, 2.5, and 5.0 micrograms/ml of BrdU, rose rapidly from 0.1 to 0.25 microgram/ml, and less rapidly at higher concentrations, thus reaching a saturation level. The analysis of variance, performed on the square root transformed data at 0.1 and 5 micrograms/ml of BrdU, indicated significant differences (P < 0.001) among the four donors tested. The distribution of the SCE/cell frequencies in the cell population of the four donors followed the Poisson 'mixture' probability function, thus confirming previous findings. The spontaneous rate of SCE/cell of sheep is compared with those previously reported for cattle, goat and river buffalo. The theoretical and practical implications of the spontaneous sister chromatid exchanges are discussed in relation to their possible use in animal production for (a) better genetic evaluation of the breeding animals under selection, (b) more precise monitoring of the genotoxic effects of environmental pollutants

Physicochemical and microbiological effects of different sonication times on goat's milk yogurt.

SLACA, 12. De 4 a 7 de Novembro de 2017. Ref. 71861