Previous studies have demonstrated that DNAJA1 could be a good indicator of beef toughness in Longissimus thoracis muscle from Charolais young bulls.
In conclusion, DNAJA1 is not an omnipotent marker of beef toughness with this particular data set since the correlation of its expression level with shear force values varies according to slaughtering conditions and ageing time.
Keywords: DNAJA1; Tenderness; Beef muscles; Electrical stimulation; Ageing
Knowledge of gene expression profiles has identified the gene DNAJA1, which is strongly and negatively related to tenderness, explaining up to 63% of variation in tenderness (Bernard et al., 2007).
The DNAJA1 gene encodes a member of the 40 kDa heat shock protein family (Hsp40), which is a co-chaperone of the 70 kDa heat shock protein family (Hsp70) which affects protein folding and mitochondrial protein import.
The objective of this study was to relate DNAJA1 expression to beef toughness in muscles that may differ in tenderness and to evaluate RNA integrity and expression of the DNAJA1 gene during meat ageing in non-electrically and electrically stimulated muscles.
Primers and probes for DNAJA1 gene (the genetic marker for beef tenderness) were designed by the Nucleic Acid Facility of the Pennsylvania State University using sequence data from Genbank and the real-time PCR probe/primer design software Primer Express (v2.0, Applied Biosystems).
Ct values of the DNAJA1 gene and the reference gene 18S were used with the delta Ct method (Livak and Schmittgen, 2001) to determine relative levels of DNAJA1 gene expression.
DNAJA1 expression relative to that of 18S RNA did not significantly differ between muscle type and treatment (with or without electrical stimulation) at the time of slaughter.
Correlations between DNAJA1 Expression and Shear Force Value
In contrast, the gene for chaperone protein, DNAJA1, showed reduced expression in the STR cohort.
(136) HSP90 overexpression has been reported in MPM, (88) and DNAJA1, a member of the HSP40 family, showed decreased expression in MPM with short-term recurrence of the disease.