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Transmission of the cytochrome c structural gene in horse-donkey crosses
Insights
Donkey and horse cytochrome c differ by one amino acid. Mules and hinnies inherit equal amounts of both, indicating simple Mendelian inheritance of the cytochrome c gene in the nuclear genome.
Area of Science:
- Genetics
- Molecular Biology
- Evolutionary Biology
Background:
- Cytochrome c is a vital protein in cellular respiration.
- Comparing cytochrome c across species can reveal evolutionary relationships and genetic inheritance patterns.
Purpose of the Study:
- To investigate the genetic inheritance of cytochrome c in horse-donkey hybrids (mules and hinnies).
- To determine if the cytochrome c gene is sex-linked or exhibits dominance.
Main Methods:
- Amino acid sequencing of donkey and horse cytochrome c.
- Analysis of cytochrome c composition in hybrid animals (mules and hinnies) from different tissues.
- Comparison of inheritance patterns with Mendelian genetics principles.
Main Results:
- Donkey cytochrome c differs from horse cytochrome c by a single amino acid substitution (serine for threonine at position 47).
- Mules and hinnies possess equal proportions of both horse and donkey cytochrome c, irrespective of sex or tissue type (heart vs. skeletal muscle).
Conclusions:
- Cytochrome c is inherited in horse-donkey crosses as a simple Mendelian trait.
- The gene for cytochrome c is located in the nuclear genome and is neither sex-linked nor dominant.
Abstract:
Donkey cytochrome c was shown to differ from horse cytochrome c by having a serine in position 47 rather than a threonine. The rest of the amino acid sequences are identical. Mules and hinnies, both males and females, carry equal amounts of horse and donkey cytochromes c. The same ratio is found in hinnies in preparations from heart tissue and from skeletal muscle. These results demonstrate that cytochrome c is transmitted in horse-donkey crosses as a simple Mendelian character which is neither sex-linked nor shows dominance. The cytochrome c gene is therefore located in the nuclear genome, as earlier shown to be the case for Saccharomyces iso-1-cytochrome c.