The Effect of Weight Loss on the Muscle Proteome in the Damara, Dorper and Australian Merino Ovine Breeds.

Seasonal Weight Loss (SWL) is an important constraint, limiting animal production in the Tropics and the Mediterranean. As a result, the study of physiological and biochemical mechanisms by which domestic animal breeds respond to SWL is important to those interested in animal breeding and the improvement thereof. To that end, the study of the proteome has been instrumental in gathering important information on physiological mechanisms, including those underlying SWL. In spite of that, little information is available concerning physiological mechanisms of SWL in production animals. The objective of this study was to determine differential protein expression in the muscle of three different breeds of sheep, the Australian Merino, the Dorper and the Damara, each showing different levels of tolerance to weight loss (low, medium and high, respectively). Per breed, two experimental groups were established, one labeled "Growth" and the other labeled "Restricted." After forty-two days of dietary treatment, all animals were euthanized. Muscle samples were then taken. Total protein was extracted from the muscle, then quantified and two-dimensional gel electrophoresis were conducted using 24 cm pH 3-10 immobiline dry strips and colloidal coomassie staining. Gels were analyzed using Samespots® software and spots of interest were in-gel digested with trypsin. The isolated proteins were identified using MALDI-TOF/TOF. Results indicated relevant differences between breeds; several proteins are suggested as putative biomarkers of tolerance to weight loss: Desmin, Troponin T, Phosphoglucomutase and the Histidine Triad nucleotide-binding protein 1. This information is of relevance to and of possible use in selection programs aiming towards ruminant animal production in regions prone to droughts and weight loss

Plasma concentrations of leptin and insulin (mean (s.e.)) in three breeds of sheep fed a diet maintaining or restricting growth.

<p>Plasma concentrations of leptin and insulin (mean (s.e.)) in three breeds of sheep fed a diet maintaining or restricting growth.</p

Two-dimensional gel electrophoresis.

<p>Example of a 2D gel for a merino ram gastrocnemius muscle, showing the spots that were selected for identification. Molecular mass markers (MM, vertical scale), as well as the isoelectric point (pI, horizontal scale are also presented. Two-dimensional electrophoresis was carried out in linear 24 cm Immobiline DryStrips (pH 3–10). Gels were stained with colloidal Coomassie Blue G-250.</p

Live weight changes (kg ± standard deviation) for Damara, Dorper and Merino breeds assigned to either a restricted or growth diet.

<p>Live weight changes (kg ± standard deviation) for Damara, Dorper and Merino breeds assigned to either a restricted or growth diet.</p

Two-dimensional gel electrophoresis.

<p>Examples of 2D gels obtained for the muscle tissue of Merino, Damara and Dorper rams. Molecular mass markers (MM, vertical scale), as well as isoelectric point (horizontal scale) are also presented. Two-Dimensional electrophoresis was carried out in linear 24cm Immobiline dry strips (pH 3–10). Six hundred micrograms of protein were loaded per gel. Staining was performed with Colloidal Coomassie Blue G-250.</p