|Budget Amount *help
¥13,300,000 (Direct Cost : ¥13,300,000)
Fiscal Year 1998 : ¥3,700,000 (Direct Cost : ¥3,700,000)
Fiscal Year 1997 : ¥9,600,000 (Direct Cost : ¥9,600,000)
Honeybee is a social insect and many exquisite communications are performed among the colony members such as "dance launguage". However, the molecular basis that underlies such highly advanced types of honeybee behavior is largely unknown. The mushroom bodies (MB), which are supposed to be a main center of the senssory integration and memory, are characteristically well-developed in comparison with those of other insects. Thus, the increased complexity of the function and structure of the MB might be due to the highly advanced types of honeybee bahavior. Here, we searched for genes that are expressed preferentially in the MB by the differential display method as candidate genes that regulate the honeybee behavior, and obtained the following results.
1. The intrinsic ceuron cells that consist the MB are subdivided into two classes : the large-and small-type Kenyon cells. A gene which is expressed specifically in the large-type Kenyon cells, termed M5, and a gene which is expressed specif
ically in the small-type Kenyon cells, termed Ks, are identified for the first time. cDNAs for these genes did not contain significant long open reading frames, suggesting that the M5 and Ks gene transcripts function as non-translated RNAs. In situ hybridization analysis of the M5 gene transcripts in the pupal brain revealed that the honeybee MB is a quadruple structure consisting of four clonal units, each of wich contains two distinct areas that express different genes. Furthure analysis of the functions of these gene products will reveal the subdivision of the inner structure of the MB that uinderlie the honeybee behavior.
2. We showed that the expression of the genes for proteins involved in the intracellular calcium signal transduction was up-regulated in the MB of the honeybee. In contrast, in Drosophila, these genes were reported to be expressed ubiquitously thoroughout the brain cortex. Calcium signal transduction system of the neural cell has been reported to be involved in the estabrishment of memory and learning. Thus, it seems possible that the enhancement of the function of the calcium signaling contributes to the enhanced sinaptic plasticity of the MB of the honeybee. These findinG will be inportant from the perspective of comparative neurobiology of the insect. Less