Background Within the fall, Eastern North American monarch butterflies (Danaus plexippus) undergo a magnificent long-range migration. differentially regulated include the clock gene vrille and the locomotion-relevant tyramine beta hydroxylase gene. In addition, several differentially regulated genes (37.5% of total) are not annotated. We also identified 23 juvenile hormone-dependent genes in brain, Kcnj12 which separate reproductive from non-reproductive monarchs; genes involved in longevity, fatty acid metabolism, and innate immunity are upregulated in non-reproductive (juvenile-hormone deficient) migrants. Conclusion The results link key behavioral traits with gene expression profiles in brain that differentiate migratory from summer butterflies and thus show that seasonal changes in genomic function help define the migratory state. Background Eastern North American monarch butterflies (Danaus plexippus) undergo a spectacular fall migration during which they travel distances up to ~4000 km to reach their overwintering grounds in central Mexico [1]. In contrast to spring and summer butterflies, fall migrants are juvenile hormone (JH) deficient, which leads to reproductive arrest (diapause), increased longevity, and increased abdominal fat stores [2,3]. Fall migrants also use a time-compensated sun compass to help them navigate in the south/southwesterly direction [4-6]. Reproductive quiescence persists at the overwintering areas in Mexico until spring, when the butterflies break diapause, become reproductively competent, mate, and soar northward to place fertilized eggs on surfaced milkweed vegetation within the southern USA [7 recently,8]. The migrant offspring buy GSK-2193874 bring about 3 to 4 successive decades of reproductively energetic butterflies that repopulate the north selection of their habitat. It really is unclear if the successive decades of springtime and summer season butterflies have focused trip activity towards the north and/or if they are following a progressive northerly upsurge in milkweed great quantity, while staying away from undue heat tension that would happen if they continued to be buy GSK-2193874 within the southern USA throughout the summer season [7]. The late-July/early-August decades of summer season butterflies, a few of whose offspring become fall migrants, look like the best exemplory case of butterflies that usually do not show focused trip behavior [9,10]. Nevertheless, the precise kind of flight behavior that the summertime monarchs manifest is not rigorously examined actually. Additionally it is unclear whether JH insufficiency and the associated reproductive quiescence are necessary for ongoing time-compensated sunlight compass orientation in fall migrants. We lately developed a mind expressed sequence label (EST) reference for monarch butterflies that probably represents ~50% of genes within the monarch genome [11]. Using high-density microarrays from the 9417 unique cDNA sequences in buy GSK-2193874 the EST resource, a blueprint of gene expression patterns can be compared and contrasted between different conditions that may help define the molecular substrates that characterize the summer and migratory states. Here we show that increasing JH activity to induce summer-like reproductive development in fall migrants did not alter directional flight behavior or its time-compensated orientation, as monitored in a flight simulator. Summer butterflies, on the other hand, uniformly failed to exhibit directional, oriented flight. Microarray analysis revealed 40 JH-independent genes whose differential expression in brain correlated with directional flight behavior in fall migrants. Moreover, we have identified 23 JH-dependent genes in brain, which separate reproductive from non-reproductive butterflies. These data provide an unprecedented foray into the genomic regulation of migratory behaviors in monarch butterflies. Results and discussion Increased juvenile hormone activity in migrants does not disrupt directed flight or time-compensated orientation Because several aspects of migratory behavior are a consequence of continued JH deficiency, for example, reproductive quiescence and increased longevity [2,3], we examined whether the oriented flight behavior characteristic of fall migrants also depends on persistent JH insufficiency. This was evaluated by increasing JH activity with the potent JH analog methoprene [12] and then monitoring the effect on reproductive state and time-compensated flight orientation. Preliminary studies showed that the topical treatment buy GSK-2193874 of migrants with 200 g of methoprene on day 1 and day 3 consistently led to.