Transmission of the cytochrome c structural gene in horse-donkey crosses.

The research discovers how the cytochrome c gene is transmitted in the offspring of horse-donkey crosses, highlighting it’s not sex-linked or dominant and is located in the nuclear genome.

Understanding the cytochrome c gene within the context of horse-donkey crosses

• The research focuses on analyzing the transmission of the cytochrome c gene in horse-donkey hybrids, namely mules and hinnies.
• The study found that donkey cytochrome c differed from that of the horse by the presence of serine at position 47 instead of a threonine. However, the rest of the amino acid sequences remained the same.

Inheritance pattern of cytochrome c gene

• In both mules and hinnies, the cytochrome c gene was present in equal amounts from both parent species – the horse and the donkey.
• This uniform amount was observed in both the heart tissue and skeletal muscle of hinnies, suggesting that the construction and distribution of cytochrome c are consistent across different body tissues in the hybrids.
• This pattern of inheritance demonstrated that the cytochrome c gene is a simple Mendelian trait, meaning it adheres to the laws of inheritance proposed by Gregor Mendel.
• Importantly, the cytochrome c gene did not exhibit sex-linked traits or dominance, which means it’s not linked to the sex chromosomes and neither version of the gene (from the horse or the donkey) routinely masks the other.

Location of the cytochrome c gene

• From these findings, the researchers concluded that the cytochrome c gene is located within the nuclear genome of the offspring, which means it resides in the DNA contained in the nucleus of the cell.
• The conclusion aligns with previous studies on Saccharomyces iso-1-cytochrome c, a particular form of cytochrome c in yeast, that also showed the gene’s location to be in the nuclear genome.