Ajay S. Mathuru
• Yale-NUS College, 12 College Avenue West, #01 - 201, Singapore 138610
• Mechanisms Underlying Behavior, IMCB, 61 Biopolis Way, Singapore 138673
Published online in Scientific Reports on 8 November 2016.
Corresponding author: email@example.com or ajay.mathuru@yale-NUS.edu.sg
This article received extensive social media and press coverage including ScienceDaily, PhysOrg and Eurekalert and Asian Scientist.
In the late 1930s, Karl von Frisch reported that semiochemicals released upon injury, act as alarm substances (Schreckstoff) in fish. In Ostariophysi species, club cells in the epidermis are believed to contain cues related to alarm substance; however, the function of club cells, primarily as reservoirs of alarm substance has been debated. Here, I describe an alarm response in the Japanese rice fish Oryzias latipes(medaka), a member of the order Beloniformes. The response to alarm substance (Schreckreaction) in medaka is characterized by bouts of immobility and an increase in cortisol levels within minutes of exposure to conspecific skin extract. Histological analysis, however, suggests that club cells are either rare or absent in the medaka epidermis. In addition to describing an uncharacterized behavior in a vertebrate popular for genetic and developmental studies, these results support the hypothesis that the primary function of epidermal club cells may be unrelated to a role as alarm substance cells. The existence of similar behavioral responses in two evolutionarily distant but well established laboratory models, the zebrafish and the medaka, offers the possibility of comparative analyses of neural circuits encoding innate fear.
Medaka become immobile with fear when they smell alarm cues released upon injury of one of their kind.
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