Evolutionary changes in the developmental expression of silkmoth chorion genes and their morphological consequences

Area of Science:

• * Evolutionary developmental biology
• * Insect reproductive biology
• * Molecular genetics

Background:

• * Silkmoth choriogenesis involves complex evolutionary modifications.
• * Morphological differences in chorion structure exist between species like Antheraea polyphemus and Hyalophora cecropia.
• * Aeropyle crowns are late-stage choriogenesis structures with species-specific variations.

Purpose of the Study:

• * To investigate the molecular basis for evolutionary changes in silkmoth chorion morphology.
• * To compare gene expression patterns during late choriogenesis in A. polyphemus and H. cecropia.
• * To test the hypothesis that regulatory changes drive chorion evolution.

Main Methods:

• * Comparative analysis of chorion morphology between A. polyphemus and H. cecropia.
• * Examination of protein synthesis profiles during late choriogenesis.
• * Quantification of specific gene (E1, E2) RNA abundance via molecular techniques.

Main Results:

• * A. polyphemus possesses prominent aeropyle crowns, absent in H. cecropia, due to differences in filler substructure.
• * Late-stage protein synthesis differs significantly, with reduced abundance of specific proteins in H. cecropia.
• * E1 and E2 RNA levels are substantially higher in A. polyphemus, despite similar gene copy numbers and expression timing.

Conclusions:

• * Evolutionary divergence in silkmoth chorion morphology likely stems from regulatory alterations in chorion gene expression.
• * Changes in transcription or mRNA decay rates are proposed mechanisms.
• * The findings support a model of evolutionary change based on regulatory shifts rather than solely terminal additions.