The four hexamerin genes in the honey bee: structure, molecular evolution and function deduced from expression
Juliana R Martins1, Francis M F Nunes, Alexandre S Cristino
1Faculdade de Medicina de Ribeirão Preto, Departamento de Genética, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
BMC Molecular Biology
|March 30, 2010
Summary
Honey bee hexamerin genes show diverse structures and expression patterns, regulated by juvenile hormone (JH). These proteins are crucial for metamorphosis, reproduction, and foraging, with complex evolutionary histories.
Area of Science:
- Insect Molecular Biology
- Evolutionary Genetics
- Biochemistry
Background:
- Hexamerins are hemocyanin-derived storage proteins in insects.
- They have lost oxygen transport function.
- This study investigates honey bee hexamerin genes.
Purpose of the Study:
- Explore structural characteristics of honey bee hexamerin genes.
- Analyze their expression profiles across castes and life stages.
- Investigate their evolutionary relationships and functions.
Main Methods:
- Bioinformatic analysis of gene structure and upstream control regions (UCRs).
- In vivo experiments involving juvenile hormone (JH) application.
- Gene expression analysis using transcript levels in various tissues and developmental stages.
- Phylogenetic analysis of hexamerin proteins.
Main Results:
- Four honey bee hexamerin genes (hex 70a, hex 70b, hex 70c, hex 110) exhibit significant structural divergence (30-42% amino acid identity).
- A potential Ultraspiracle (Usp) binding site, a target of JH, was identified in UCRs, and JH application induced gene expression in larvae.
- Gene expression is high in the larval fat body, with specific re-induction in adult fat body (hex 110, hex 70a) and gonads (hex 110, hex 70a, hex70b), particularly in queens.
- Phylogenetic analysis places HEX 110 basally and suggests orthology with other hymenopteran hexamerins.
Conclusions:
- Honey bee hexamerins display distinct structures and developmental expression patterns.
- Regulation by JH is supported by Usp binding site presence and experimental data.
- Hexamerins function in metamorphosis, gonad development, egg production, and foraging support.
- Evolutionary analysis reveals complex patterns with independent radiation across insect orders.
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