Molecular study of ovine glucose 6-phosphate dehydrogenase gene expression in respect to different energy intake

Glucose 6-phosphate dehydrogenase (G6PD) plays an important role in a ruminant's metabolism catalyzing the first committed reaction in the pentose phosphate pathway as it provides necessary compounds of NADPH for the synthesis of fatty acids. The cloning of ovine (Ovis aries) G6PD gene revealed the presence of two cDNA transcripts (oG6PDA and oG6PDB), with oG6PDB being a product of alternative splicing and with no similarity to any other previously reported G6PD transcript. Here, we attempt to study the effect of energy balance in ovine G6PD transcript expression, trying simultaneously to find out any potential physiological role of the oG6PDB transcript. Changes of energy balance that lead to synergistic changes in the expression of both transcripts, but in opposite directions and not in a proportional way. Negative energy balance favours the presence of the oG6PDB transcript leading to a significant increase of its expression, compared to oG6PDA expression (P < 0.05). In contrast, positive energy balance leads to a significant increase of oG6PDA compared to oG6PDB expression (P < 0.05). In either condition oG6PDB expression is unchanged. Regression analysis showed that there is an energy balance threshold where the expression of both transcripts shows no change.