Identification of selection signatures in livestock species.

The identification of regions that have undergone selection is one of the principal goals of theoretical and applied evolutionary genetics. Such studies can also provide information about the evolutionary processes involved in shaping genomes, as well as physical and functional information about genes/genomic regions. Domestication followed by breed formation and selection schemes has allowed the formation of very diverse livestock breeds adapted to a wide variety of environments and with special characteristics. The advances in genomics in the last five years have enabled the development of several methods to detect selection signatures and have resulted in the publication of a considerable number of studies involving livestock species. The aims of this review are to describe the principal effects of natural/artificial selection on livestock genomes, to present the main methods used to detect selection signatures and to discuss some recent results in this area. This review should be useful also to research scientists working with wild animals/non-domesticated species and plant biologists working with breeding and evolutionary biology.

Resistance and virulence in Staphylococcus aureus by whole-genome sequencing: a comparative approach in blaZ-positive isolates.

Mastitis caused by Staphylococcus aureus is a worldwide problem in dairy farms, in part because of the pathogenicity of the bacteria, biofilm formation, and mechanisms of antimicrobial resistance that make the disease difficult to diagnose and treat, which is typically done with the use of beta-lactam antibiotics. The aim of the present study was to determine the virulence and resistance factors of S. aureus isolates from subclinical mastitis, blaZ + /mecA - /mecC - , resistant and sensitive to oxacillin. All isolates were classified as CC97 by MLST analysis, a clonal complex well adapted to the mammary gland and although STAU23 and STAU73 were resistant to oxacillin while STAU32 and STAU78 were sensitive, the genomic analysis identified only the blaZ operon corresponding to resistance to beta-lactams. However, the presence of the sdrC gene was revealed exclusively in resistant isolates, an important adhesin in the colonization process that potentiates pathogenicity in S. aureus. In addition, resistance islands (REIs) were identified in these isolates, suggesting more conserved REIs. In the analysis of SNPs throughout the genome, mutations were found in the trmB and smpB genes of the resistant isolates and in the murD and rimM genes of the sensitive isolates. This study highlights the potential benefit of genome-wide characterization tools to identify molecular mechanisms of S. aureus in bovine mastitis.

Action of crude ethanol extract of Hymenaea martiana leaf, gallic acid, and polypyrrole (PPy) against Aeromonas hydrophila.

Pisciculture represents one of the industries with the fastest growth rates worldwide. However, it presents obstacles to its development, such as bacteriosis, which is conventionally treated with antibiotics. The indiscriminate and inappropriate use of antibiotics can lead to bacterial resistance, thus alternatives to the use of antibiotics have been researched. The study aimed to analyze the potential of crude ethanol extract (CEE) from Hymenaea martiana leaf, gallic acid (GA), and polypyrrole (PPy) against Aeromonas hydrophila. Tests were performed to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the compounds individually and in synergy (checkerboard) against A. hydrophila and in silico tests between the compounds evaluated. The CEE of H. martiana leaf and PPy were effective against A. hydrophila with MBC results of 3125 µg/mL for the CEE of H. martiana and 125 µg/mL for PPy. Evaluating the GA, a MIC and MBC of 125 µg/mL was obtained. In the interaction tests (checkerboard, using PPy/CEE and PPy/GA), there was a significant reduction in individual introductions. Thus, for the PPy/CEE tests, we had a reduction of MIC/MBC to 1.95 and 781.25 µg/mL, and for the synergy tests between PPy/GA to 7.8125 and 31.125 µg/mL, respectively. The synergy tests are encouraging, and it is possible to verify a decrease of up to 98% in the introduction of PPy, 75% in CEE for H. martiana and 75.1% for GA, when compared to their individual tests. The tests with GA are encouraging due to GA's effectiveness as an antimicrobial agent and high synergy with polypyrrole, both in vitro results and molecular docking experiments showed the actions at the same activation site in A. hydrophila. In vivo tests evaluating isolated components of CEE from H. martiana in synergy with PPy should be performed, to verify the quality of the interactions and the improvement of the immune responses of the animals. It was evidenced that gallic acid, a substance isolated from the extract, tends to have more promising results. This is relevant since the industry has been developing these compounds for different uses, thus providing easier access to the product. Thus, the present study indicates an efficient alternative in the use of bioactive compounds as substitutes for conventional antimicrobials.

Tannin as a modulator of rumen microbial profile, apparent digestibility and ingestive behavior of lactating goats: A preliminary metagenomic view of goats adaptability to tannin.

The aim with this study was to use interdisciplinary techniques and visions in order to identify the modulating effect of tannins on adaptive factors in lactating goats with different genetic patterns, through the assessment of digestibility and nutrient intake, ingestive behavior and rumen metagenome. We used in this study 8 of the Repartida ecotype and 6 of the Canindé breed goats, on average five years old, distributed in a completely randomized design, in a 2 × 2 factorial design, with two genetic groups and two diets. The applied diets were: basal diet and inclusion of 5% commercial tannin extract in basal diet. Intake and apparent digestibility of nutrients were evaluated, based on the quantification of the offered feed and refusals, and bromatological evaluation of samples of the offered feed, refusals and feces. Behavioral data were collected in 24-h continuous visual observations. The ruminal fluid was collected and DNA extraction, sequencing, and evaluation of relative abundance of the rumen microbiome were performed. The data obtained were analyzed statistically, through analysis of variance with 5% significance and, when necessary, a comparison of means test was applied. In this preliminary findings was observed that the genetic group factor caused changes in the number of chews and the relative abundance of microorganisms (P = 0.0290 and P = 0.0051). The diet factor influenced digestibility, which better values were observed for the tannin diet (P = 0.0049), in addition, it promoted changes in the rumen microbiota, with a beneficial modulatory characteristic. The inclusion of 5% tannin extract from Acacia mearnsii modulates the rumen microbiome, improving the apparent digestibility of nutrients without affecting the feed intake of goats from the Repartida and Canindé genetic groups.