Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen, and ruminants are recognized as the main natural reservoir. The purposes of this study were to detect E. coli O157 in bovine feces and surface water in a beef cattle farm of Gualeguaychú, Argentina; to characterize the isolates; and to establish the clonal relatedness by pulsed-field gel electrophoresis. Between September 2005 and November 2006, 288 samples of bovine feces and 79 samples of water troughs were studied. E. coli O157 was detected by immunomagnetic separation and polymerase chain reaction as screening techniques. The rfb(O157) gene was detected in 3.8% of the 288 fecal samples and in 17.7% of the 79 water samples. The stx gene was detected in all rfb(O157)-positive fecal samples and in 5.1% of water samples. Eleven E. coli O157 strains isolated from bovine fecal samples and eight from water samples were characterized. The most frequent stx genotype identified was stx(1) and stx(2c(vh-a)). Twelve (63.2%) strains harbored fliC(H7), eae, and ehxA genes. Using pulsed-field gel electrophoresis with the enzyme XbaI, a total of eight patterns with at least 72.1% similarity were identified among the 19 strains. The patterns of 15 strains were grouped into four clusters: two of them included only bovine strains and the other two only aquatic strains. No genetic correlation was established between the bovine and water STEC strains detected. The prevalence of STEC O157:H7 established in the herd studied was higher than that previously reported for Argentine grazed cattle.
Medical genetics is a field marked by fast progress. Even though it was at one point confined to a group of relatively rare diseases, today it has become a central component in the understanding of disorders and it is the subject of interest for all medical specialties. This paper, shares data on the chromosomal alterations and variations that have been diagnosed in Ecuadorian patients since 1998. A total of 2,636 individual cases have been analyzed by G-banding technique until February 2012. The present work shows this collection of data and the important findings that have appeared throughout these years in hopes that it can contribute to have a deeper understanding of the incidence of chromosomal aberrations and alterations in the Ecuadorian population.
A new set of microsatellite loci (simple sequence repeats, SSRs) from the overexploited mangrove crab Ucides cordatus is described in this study. Microsatellite isolation used a highly simplified and inexpensive protocol based on (i) multiple enzyme digestion/ligation; (ii) mixed biotin-labeled probes and streptavidin-coated magnetic bead hybridization capture strategy, and (iii) a double-repeat-enrichment procedure. A genomic library, double-enriched for inserts containing tetranucleotide repeat motifs [(GACA)6, (GATA)7, (GGAT)5 and (GTAT)5], was constructed to increase the chance of recovering SSR-containing sequences within DNA fragments. Amplified enriched DNA was cloned and transformed into competent E. coli. Then, positive clones were identified by 'white/blue plaque selection?. One hundred and five colonies were PCR-screened for sequencing, and 72 of these were found to have unique SSR inserts. Microsatellite motifs contained more than five repeats, and most loci were found to have perfect tandem repeats (51.4%), of which 94.4% were dinucleotide and 5.5% trinucleotide. Only 20% of all loci were compound and 28.6% were imperfect repeats containing di-, tri- and/or tetranucleotides. The high frequency of perfect repeat motifs after enrichment is additional evidence of the importance of adopting this procedure for the isolation of SSR. The novel 34 SSRs described in this study are expected to be highly polymorphic and, therefore, useful in population/stocks discrimination of this valuable mangrove species throughout its range, currently subjected to excessive fishing efforts.
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