Transcriptome analysis of the brain under diapause and nondiapause conditions in the blowfly <i>Protophormia terraenovae</i>

<jats:title>Abstract</jats:title><jats:p>The blow fly <jats:italic>Protophormia terraenovae</jats:italic> responds to photoperiod and temperature to control reproductive diapause. Differentially expressed genes (<jats:styled-content style="fixed-case">DEG</jats:styled-content>s) in the brain are investigated under diapause‐inducing and diapause‐averting conditions in search of potential genes for diapause induction. Total <jats:styled-content style="fixed-case">RNA</jats:styled-content> is extracted from female brains 1–2.5 days after adult emergence under an <jats:styled-content style="fixed-case">LD</jats:styled-content> 18 : 6 h photocycle at 25 °C as nondiapause samples and 3, 3.5, 7 and 7.5 days after adult emergence under an <jats:styled-content style="fixed-case">LD</jats:styled-content> 12 : 12 h photocycle at 20 °C as diapause samples. From our transcriptome analysis, 626 350 654 reads are assembled into 126 231 contigs, from which 46 844 contigs (37.1% of the total) are annotated as protein‐coding genes. Among them, the expression levels in 549 contigs are specifically up‐regulated under diapause‐inducing (44.1%) or diapause‐averting (55.9%) conditions. Using quantitative real‐time reverse transcriptase‐polymerase chain reaction analysis, higher expression levels under diapause‐inducing conditions are found in a contig encoding <jats:italic>angiotensin‐converting enzyme</jats:italic> (<jats:italic>ACE</jats:italic>). Expression levels of the contig significantly increase 3 days after changing the photoperiod to diapause‐inducing short days. Rabbit antisera against 17 amino acid peptides included in <jats:italic>P. terraenovae</jats:italic>‐<jats:italic>ACE</jats:italic> stain one pair of cells lateral to the oesophageal foramen. These results suggest that the expression of a small number of genes is associated with the regulation of diapause in response to photoperiod and temperature, and <jats:italic>ACE</jats:italic> in the immunoreactive cells might respond to short days, which is why it is involved in diapause induction.</jats:p>