Screening of differentially expressed genes induced by water-soluble extracts from pollen during honeybee caste determination

In order to screen differentially expressed genes during caste differentiation induced by pollen, larvae of Apis mellifer ligustica were developed in an incubator under controlled temperature and relative humidity until emergence. Worker bee morphology was induced by addition of water-soluble extracts from pollen in larval diets. After all of the developmental periods, the external characters and developmental degree of ovaries were evaluated to confirm the caste of new adults. Transcripts from larvae of developing queens and workers were profiled by differential-display RT-PCR analysis and differentially expressed fragments were reconfirmed by dot-blot assay. Our results showed that caste differentiation was triggered by the intake of pollen extracts. Six transcript-derived fragments were isolated and three of them are reported for the first time. We conclude that differential display is a feasible approach to identifying differentially expressed genes. The identification of up-regulated caste-differentiation-related genes provided interesting clues about the activation of biochemical steps relevant to this progress.