Annual Report 2003

C57BL/6 KK KK-A y Multi-electrode recording of neuralFig. 3KK and KK-A y mice as obesity and diabetes models.traits on chromosomes 1, 8 and 9, repetitively.The confidence intervals of theseQTLs included plausible candidate genes,and several of them exhibited polymorphismsamong inbred strains.We have established a simple and inexpensivetechnology to produce transgenicmice by transforming male germ cells invivo. We are developing a new selectionmarker to apply our new transgenic technologyto the homologous recombination-mediatedgene knock-out technology. We are alsostudying the transcription factor which drivesmale germ cell-specific gene expression.We are studying the effects of toxic compoundson male meiotic recombination inmice to identify the basic mechanism ofgenome alteration in a germ line. We testedtwo compounds, 2, 3, 7, 8- tetrachlorodibenzop-dioxin(TCDD), and type II topoisomeraseinhibitor etoposide. Both compounds havebeen reported to induce enhancement ofrecombination in somatic cells. In our study,both compounds showed chromosomalregion-dependent suppression/enhancementof meiotic recombination.To study the immunological diversity ofJapanese domestic cattle, we surveyed polymorphismsof the major histocompatibilitycomplex (MHC) class II gene DRB3. TheDRB3 gene is located within the MHC onchromosome 23, and has major roles inimmunological function. The gene is knownto be one of the most polymorphic genes inthe bovine genome. We collected genomicDNA samples from Japanese domestic cattle(Wagyu) in two locations, Yamagata andShimane, and analyzed genetic polymorphismsof the DRB3 gene at the molecularlevel. We found that the DRB3 gene in bothpopulations was extensively polymorphic.P hysiology and Genetic Regulation DepartmentFig. 1Examples of spike waveforms from five neurons recorded simultaneouslyby multi-channel microelectrodes. Each neuron was clearly discriminated.activity in the insect brainTo understand how the odor informationis encoded in the antennal (olfactory) lobe ininsects, it is important to first understandthe relationship between spatial and temporalproperties of neuron responses. Usingthe multi-electrode techniques originallydeveloped for the mammalian brain, odorevokedresponses from many neurons withinthe lobe of Periplaneta americana wererecorded simultaneously. The findings confirmedthat the method can be used toexplore the dynamic, spatially organized78 Annual Report 2003