Abstract
BackgroundThe use of growth-promoters in beef cattle, despite the EU ban, remains a frequent practice. The use of transcriptomic markers has already proposed to identify indirect evidence of anabolic hormone treatment. So far, such approach has been tested in experimentally treated animals. Here, for the first time commercial samples were analyzed.ResultsQuantitative determination of Dexamethasone (DEX) residues in the urine collected at the slaughterhouse was performed by Liquid Chromatography-Mass Spectrometry (LC-MS). DNA-microarray technology was used to obtain transcriptomic profiles of skeletal muscle in commercial samples and negative controls. LC-MS confirmed the presence of low level of DEX residues in the urine of the commercial samples suspect for histological classification. Principal Component Analysis (PCA) on microarray data identified two clusters of samples. One cluster included negative controls and a subset of commercial samples, while a second cluster included part of the specimens collected at the slaughterhouse together with positives for corticosteroid treatment based on thymus histology and LC-MS. Functional analysis of the differentially expressed genes (3961) between the two groups provided further evidence that animals clustering with positive samples might have been treated with corticosteroids. These suspect samples could be reliably classified with a specific classification tool (Prediction Analysis of Microarray) using just two genes.ConclusionsDespite broad variation observed in gene expression profiles, the present study showed that DNA-microarrays can be used to find transcriptomic signatures of putative anabolic treatments and that gene expression markers could represent a useful screening tool.
Highlights
The use of growth-promoters in beef cattle, despite the EU ban, remains a frequent practice
Microarray analysis has been used so far to examine the effects of anabolic hormones in experimentally treated animals, as in the case of skeletal muscle samples from bulls administered with Dexamethasone (DEX) and DEX plus 17β-estradiol [13], and with trenbolone acetate plus estradiol [14], or livers from beef cattle after experimental treatment with dehydroepiandrosterone [15]
Liquid Chromatography-Mass Spectrometry (LC-MS) analyses LC-MS analyses were performed on urine from the slaughtered animals to obtain an analytical confirmation for the thymus histological results [17]
Summary
The use of growth-promoters in beef cattle, despite the EU ban, remains a frequent practice. The use of transcriptomic markers has already proposed to identify indirect evidence of anabolic hormone treatment Such approach has been tested in experimentally treated animals. New Anabolic steroids act on multiple organs and metabolic pathways either through primary interaction or secondary effects For this reason, indirect approaches, based on the evaluation of perturbations of different biological systems, have been proposed to identify growth-promoter-treated animals. Toxicogenomics has mostly focused on the effects of pharmacological compounds in model species, it is increasingly applied to monitor the effects of xenobiotics in non-model species (e.g. eco-toxicogenomics) In this contest, gene expression profiles have been used to obtain indirect biomarkers for the use of growth promoters in beef meat production. The potentiality of RNA- sequencing technology for the detection of growth-promoters abuse in cattle was explored and successfully used to screen for highly regulated genes to be proposed as biomarker candidates for detecting the treatment with trenbolone acetate plus estradiol [16]
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