Provide a description of the cellular mechanisms by which one reciprocal cross leads to hybrid dysgenesis while the other does not
What will be an ideal response?
The M cytotype is normal, while the P cytotype has multiple P elements and a repressor protein within the cytoplasm to block transposition. When the male has the P cytotype, he has multiple transposable elements but the ovum provides the vast majority of cytoplasm to the offspring relative to the sperm. Thus, there is no transposition repressor protein present in the
M-cytotype female, and the P elements create widespread mutation by unrepressed insertional inactivation of genes. When the female has the P cytotype, the embryo will have multiple P elements but will also have large amounts of the transposition repressor protein within the cytoplasm. This represses the widespread insertional inactivation events that lead to hybrid dysgenesis in the reciprocal cross, so the offspring are healthy and fertile.
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