Recently, the existence of non-neuronal, soluble AChEs with non-classical functions, such as stress response and chemical defense, has been reported in both vertebrates and invertebrates. With this in mind, it is intriguing to hypothesize that fat body is a main tissue to express non-neuronal AChE at least in some insects. As an initial step for the systematic approach to investigate the distribution of non-neuronal AChEs in insect fat body and to elucidate their physiological functions, we have selected 12 different insect species across different orders and isolated fat body tissues from them. Then, the presence or absence of AChE and its solubility nature were determined by native polyacrylamide gel electrophoresis in conjunction with western blot analysis insect-specific AChE1 and 2 antibodies. Among 12 insects examined, soluble AChE1 was determined to be expressed in fat bodies of insects involving honey bees, brown plant hoppers, dynastid beetles, lice, etc, AChE2 in fruit flies, bed bugs, mealworm beetles. However, no AChE was detected in fat bodies of the remaining two species American cockroaches and dragonflies Our findings clearly show that AChE is widely distributed in the fat body tissue of diverse insect species. More extensive investigation on in a wider variety of insect species would be necessary to deduce the evolutionary origin of fat body-specific AChE, which would be the ancestor of AChE with non-neuronal function.

• Seunghee Han(Department of Agricultural Biology, Seoul National University)
• Sanghyeon Kim(Department of Agricultural Biology, Seoul National University)
• Si Hyeock Lee(Department of Agricultural Biology, Seoul National University Research Institute of Agriculture and Life Sciences, Seoul National University)