Visualization of Neural Activity in Insect Brains Using a Conserved Immediate Early Gene, Hr38

Abstract

Many insects exhibit stereotypic instinctive behavior [1-3], but the underlying neural mechanisms are not well understood due to difficulties in detecting brain activity in freely moving animals. Immediate early genes (IEGs), such as c-fos, whose expression is transiently and rapidly upregulated upon neural activity, are powerful tools for detecting behavior-related neural activity in vertebrates [4, 5]. In insects, however, this powerful approach has not been realized because no conserved IEGs have been identified. Here, we identified Hr38 as a novel IEG that is transiently expressed in the male silkmoth Bombyx mori by female odor stimulation. Using Hr38 expression as an indicator of neural activity, we mapped comprehensive activity patterns of the silkmoth brain in response to female sex pheromones. We found that Hr38 can also be used as a neural activity marker in the fly Drosophila melanogaster. Using Hr38, we constructed a neural activity map of the fly brain that partially overlaps with fruitless (fru)-expressing neurons in response to female stimulation. These findings indicate that Hr38 is a novel and conserved insect neural activity marker gene that will be useful for a wide variety of neuroethologic studies.

PDF Signaling Is an Integral Part of the Drosophila Circadian Molecular Oscillator

“…Interestingly, dhr38 and sr were also identified as activity regulated genes in Drosophila (Fujita et al., 2013; X. Chen and M. Rosbash, personal communication) suggesting neuronal firing could regulate pdf levels. Thus, we determined whether pdf transcription is regulated by neuronal firing by using the heat-activated cation channel dTrpA1 (Rosenzweig et al., 2005) in the pdf -expressing cells of flies that also carry the pdf Tomato reporter ( pdf GAL4- pdf Tomato-TRP).…”

Information flow through neural circuits for pheromone orientation

“…2a). Cell bodies were located in the area surrounding the calyx of the mushroom body (MB), in which a group of neurons that exhibit neural activity in response to the sex pheromone are present 22 . All neurons with smooth processes, which is an indicator of a postsynaptic terminal 23 , within the DILPC showed a transient excitatory response to bombykol on both the ipsi-and contralateral sides (n ¼ 5 neurons, Fig.…”

Stimulation of orphan nuclear receptor HR38 gene expression by PTTH in prothoracic glands of the silkworm, Bombyx mori

“…We hypothesize that PTTH-stimulated HR38 expression lies upstream of ecdysone biosynthesis signaling. It was also interesting to note that HR38 is an IEG in pheromone-elicited response in insect brains (Fujita et al, 2013).…”

“…An antibody directed against Bombyx HR38 was kindly provided by Dr. Taketoshi Kiya (Fujita et al, 2013). An anti-a-tubulin antibody was purchased from Cell Signaling Technology (Beverly, MA, USA).…”

“…DHR38 also plays pivotal roles in adult cuticle formation, carbohydrate metabolism, and glycogen storage (Kozlova et al, 1998(Kozlova et al, , 2009Ruaud et al, 2011). More recently, HR38 was identified as a novel IEG that is transiently expressed in the male by sex pheromone in both Drosophila and Bombyx and thus HR38 can be used as a neural activity marker in insect brains (Fujita et al, 2013).…”