KUSAKABE Moriaki INSTITUTE OF PHYSICAL AND CHAMICAL RESEARCH (RIKEN), DIVISION OF EXPERIMENTAL ANIMAL RESEARCH, HEAD, 実験動物室, 部長 (60153277)
HANAI Atsuko INSTITUTE FOR DEVELOPMENTAL RESEARCH, JOINT RESEARCH RESOURCE CENTER, RESEARCH ASSISTANT, 共同研究科, 助手
|Budget Amount *help
¥3,000,000 (Direct Cost : ¥3,000,000)
Fiscal Year 1999 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1998 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1997 : ¥1,700,000 (Direct Cost : ¥1,700,000)
BUS/Idr mice are the bustling mutant displaying behavioral abnormalities such as hyperactivity, circling, head tossing and head tilting. The traits are inherited autosomally and recessively, and earlier studies have demonstrated that bus/bus homozygotes suffer auditory in addition to vestibular dysfunction, which is the cause of abnormal behavior. Linkage analysis revealed that the responsible gene, originally designated as bus, maps on chromosome 10, 1.09 ± 0.9 cM distal to D10Mit127 and D10Mit59, and 0.72 ± 0.51 cM proximal to three markers, D10Mit48, D10Mit112 and D10Mit258, at a site indistinguishable from that of the Albany waltzer, vAlb. The results of allelism tests between BUS and Albany waltzer and between BUS and waltzer indicated that bus is another allele of v gene.
As an approach to identify the v gene, we employed the PCR-based cDNA subtraction procedure, while this direct approach apparently has several draw backs; there is a possibility not to detect minor alterations in
genes such as single base substitution. By applying the method to testis mRNA fractions from BUS(+/+) and BUS(but/bus), three weeks of age, 200 EST clones with a subtracted cDNA-derived insert were obtained. BLAST searches allowed identification of the EST clones, while 52 clones contained yet unidentified ESTs. All of so far identified inserts proved to be false positive with respect to vestibulocochlear defects. Efforts are still being made to define the true EST clone associated with vestibulocochlear defects in bus/bus homozygotes.
During the course of study to identify the factor associated with the inner ear defects of BUS mice, we obtained an inner ear mRNA-derived, myosin-related unique EST clone. Subsequent studies demonstrated that the EST is a part of mouse myosin X, which is still nuclear in both the structural and functional aspects. We have identified the coding region of mouse myosin X cDNA, which allowed prediction of 240KDa molecular mass of mouse myosin X consisting of 2,062 amino acids (registered in GenBank, accession number AJ249706). Investigations of any association of this molecular motor, when defected, with genetic human disorders are under way. Less