Thesis Abstract

Double muscling is a heritable trait. It has been revealed that myostatin (MSTN) or growth differentiation factor 8(GDF8) is the genetic agent of this trait. The gene is a myokine, a protein that inhibits myogenesis (muscle cell growth and differentiation). In-Silico genetic analysis was done to analyze the sequences of Myostatin gene in cattle, sheep and goat. A total of thirty seven (37) nucleotides with their corresponding amino acid sequences comprising of (26 for goat, 9 for cattle and 2 for sheep) were retrieved from the Genebank. The genetic polymorphism with three variants (M180L, S276N, S279K), five (K178N, V151L, E247D, Q329L, G355I) and six (R98H, I119T, S125M, G133S, T165N, H328T) for goat, sheep and cattle respectively, appeared not to impair the gene function while three variants (K153F, T240K, L270Q), six (S191P, W203L, S205C, N222Q, D231C, R303G), seven (D110L, I158A, R175V, K193V, S205G, P301L, F353N) were deleterious. The results revealed beneficial amino acid variants which can be used as possible markers for growth and development in goats, sheep and cattle. Although Capra and Ovis family had more propinquity and organized branch in the phylogenetic tree, the Neigbour-joining showed that sequences of the three species are similar. Also, goats and sheep appeared more similar in their amino acid contents compared to cattle. However, the distribution pattern was the same for the three species in respect of (aspartate 6.1, cysteine 3.5, glutamate 6.7, methionine 2.1, phenylalanine 3.7, proline 6.4 and tyrosine 3.2 with leucine 9.9, as the highest). The results also showed that this gene has a high degree of conservation during evolution of various species, which implies that MSTN, is an essential factor in biological muscle control. Physicochemical properties also showed extinction coefficient =51630 for sheep and cattle, half life=30hours for goats, sheep and cattle and aliphatic index =84.45 for goats and sheep, other parameters varied from one species to anrother. The secondary protein structure prediction in the bovine myostatin protein showed highest alpha helix (23.20%) and random coil (44.00%) with caprine and ovine at 22.67% and 43.20%. However, the extended strand (25.87%) and beta turn (8.27%) predictions were higher in both caprine and ovine species with bovine at 25.33% and 7.47%. Tertiary protein structure prediction of goat and sheep are the same while that of cattle differed. Furthermore, the results showed that capra and ovis family are much similar in function compared to cattle. Finally, the comparative inferences of myostatin gene sequences of the species studied conferred similarity in goat and sheep than cattle.

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