Human chromosome-specific cDNA libraries: new tools for gene identification and genome annotation.

To date, only a small percentage of human genes have been cloned and mapped. To facilitate more rapid gene mapping and disease gene isolation, chromosome 5-specific cDNA libraries have been constructed from five sources. DNA sequencing and regional mapping of 205 unique cDNAs indicates that 25 are from known chromosome 5 genes and 138 are from new chromosome 5 genes (a frequency of 79.5%). Sequence complexity estimates indicate that each library contains -20% of the approximately 5000 genes that are believed to reside on chromosome 5. This study more than doubles the number of genes mapped to chromosome 5 and describes an important new tool for disease gene isolation.

Effect of treatment protocol and sample time on the frequencies of micronucleated polychromatic erythrocytes in mouse bone marrow and peripheral blood.

Studies were conducted to evaluate the effect of experimental protocol on the ability of benzidine (BZD), dimethylbenzanthracene (DMBA) and mitomycin C (MMC), administered by intraperitoneal injection, to induce micronuclei in polychromatic erythrocytes (PCE) of B6C3F1 mice. Three different treatment/sampling protocols were used, involving from one to three consecutive daily treatments and from three to one, respectively, consecutive daily samplings beginning 24 h after the last injection. DMBA and MMC elicited a significant micronucleus response in all three experimental protocols, while BZD induced a significant response only in the multiple injection protocols. Of the three protocols, the 3-day injection/single sample time protocol offers the greatest efficiency in minimizing the number of animals required in a study, in decreasing the time needed for scoring and in simplifying the statistical analysis. In addition, a comparison of the frequency of micronucleated PCE in peripheral blood and bone marrow following the treatment of mice with either BZD or DMBA suggests that, following a three injection protocol, either tissue can be used with equal efficacy.