International Mammalian Genome Society

The 15th International Mouse Genome Conference (2001)

Table of Contents * Complex Genetics * Developmental Genetics * Gene Annotation * Gene Discovery * Genome Sequencing * Functional Genomics * Mutagenesis * Presentations * Verne Chapman Memorial Lecture

Dr. Yoichi Gondo
RIKEN Genomic Sciences Center
Population and Quantitative Genomics Team
1-7-22 Suehiro-cho, Tsurumi-ku
Yokohama
230-0045
Japan

Co-Authors: 1)Minowa O, 2)Sezutsu H, 2)Sakuraba Y, 1)Toki H, 1)Wakana S, 1)Noda T, 1)Shiroishi T
Institutions: 1) Mouse Functional Genomics Research Group, RIKEN Genomic Sciences Center 2) Population and Quantitative Genomics Team, RIKEN Genomic Sciences Center

One of our major objectives is to screen late-onset phenotypes. In order to retain any G1 male strains, all the G1 sperms have been cryopreserved in liquid nitrogen. We developed a system that maintains more than 150,000 sperm samples in a 430L tank. Six aliquot sperm samples are made from a single G1 male. Currently, about 100 males are subjected to the vasectomy per week in our project; thus, 30,000 sperm stocks are produced per year. The remaining testes have also been stored at -80C. When a significant late-onset phenotype is found accompanied with a fatal or sterile trait, the corresponding G1 strain could be recovered from the frozen sperms at any time. G1 males are subjected to late-onset screens up to 18 months; then, pathological analyses will be conducted. At the same time, several organs will be preserved at -80C. The RNA expression profiling and the gene-based mutation assay will be conducted by using these frozen organs. In particular, high-throughput detection of mutations in the G1 genome will provide a robust tool to identify recessive mutations. Specific-locus tests indicated that ENU induces about 0.001 recessive mutation/locus/gamete. It implies that one recessive mutant for any given gene may be obtained by screening of 1000 G1 on average. Assuming that neutral or silent mutations are ten fold more than recessive mutations and that an average size of genes is 5 kb, we expect that the mutation rate is 2 X 10^-6/bp/gamete.