Australasian Microarray & Associated Technologies Association, AMATA

McCartney, RC and Dearden, PK
Biochemistry, Otago University, 710 Cumberland Street, Dunedin, Otago 9016, New Zealand

The honeybee (Apis mellifera) is a commercially valuable [1] and biologically interesting organism. The sequencing of the honeybee genome in 2006 [2] provides an opportunity to study the phenomenon of polyphenisms. Polyphenisms occur when one genome gives rise to two or more phenotypes in response to an environmental stimulus [3]. In Apis mellifera a change in diet during early development creates two very different female castes. The queen bee is larger, differs in colour and behaviour, has a greatly increased lifespan and is reproductively capable compared to sterile workers. These two castes have identical genomes indicating these differences arise through gene regulation.

There have been several different approaches aimed at investigating how the diet fed to larvae during development leads to the production of two diverse adult forms. Early studies of polyphenisms using in vitro translation established that queen and workers have different mRNA profiles [4]. Since then RNA differential display [5], subtractive hybridisation[6], differential display reverse transcription [6] have been used to try and isolate the genes and pathways involved in the developmental processes that give rise to queen or worker bees. These studies have been useful but are limited by the number of genes that can be investigated.

This study aims to identify differentially regulated genes in queen and worker bees using a honeybee microarray which will allow the simultaneous analysis of expression levels of all known honeybee genes. The array is made up of 60-69mer oligos and includes all predicted genes identified by the sequencing consortium, expressed sequence tags, bee pathogen genes and miRNA genes. Queen and worker expression profiles will be compared at various points during larval development. The arrays will provide candidate genes which will then be validated using RT-PCR. RNAi will then be used to test the role of these genes in queen development.

1. Gallai, N., et al.,, Economic valuation of the vulnerability of world agriculture confronted with pollinator decline. Ecological Economics, 2008. Article in Press.

2. Insights into social insects from the genome of the honeybee Apis mellifera. Nature, 2006. 443(7114): p. 931-49.

3. Evans, J.D. and D.E. Wheeler, Gene expression and the evolution of insect polyphenisms. Bioessays, 2001. 23(1): p. 62-8.

4. Severson, D.W., et al., Caste-specific transcription in the female honeybee. Insect Biochemistry, 1989. 19(2): p. 215-220.

5. Corona, M., E. Estrada, and M. Zurita, Differential expression of mitochondrial genes between queens and workers during caste determination in thehoneybee Apis mellifera. J Exp Biol, 1999. 202(Pt 8): p. 929-38.

6. Hepperle, C. and K. Hartfelder, Differentially expressed regulatory genes in honey bee caste development. Naturwissenschaften, 2001. 88(3): p. 113-6.