A radiation hybrid transcript map of the mouse genome.

Expressed-sequence tag (EST) maps are an adjunct to sequence-based analytical methods of gene detection and localization for those species for which such data are available, and provide anchors for high-density homology and orthology mapping in species for which large-scale sequencing has yet to be done. Species for which radiation hybrid-based transcript maps have been established include human, rat, mouse, dog, cat and zebrafish. We have established a comprehensive first-generation-placement radiation hybrid map of the mouse consisting of 5,904 mapped markers (3,993 ESTs and 1,911 sequence-tagged sites (STSs)). The mapped ESTs, which often originate from small-EST clusters, are enriched for genes expressed during early mouse embryogenesis and are probably different from those localized in humans. We have confirmed by in situ hybridization that even singleton ESTs, which are usually not retained for mapping studies, may represent bona fide transcribed sequences. Our studies on mouse chromosomes 12 and 14 orthologous to human chromosome 14 show the power of our radiation hybrid map as a predictive tool for orthology mapping in humans.

Deciphering the biology of Mycobacterium tuberculosis from the complete genome sequence.

Countless millions of people have died from tuberculosis, a chronic infectious disease caused by the tubercle bacillus. The complete genome sequence of the best-characterized strain of Mycobacterium tuberculosis, H37Rv, has been determined and analysed in order to improve our understanding of the biology of this slow-growing pathogen and to help the conception of new prophylactic and therapeutic interventions. The genome comprises 4,411,529 base pairs, contains around 4,000 genes, and has a very high guanine + cytosine content that is reflected in the biased amino-acid content of the proteins. M. tuberculosis differs radically from other bacteria in that a very large portion of its coding capacity is devoted to the production of enzymes involved in lipogenesis and lipolysis, and to two new families of glycine-rich proteins with a repetitive structure that may represent a source of antigenic variation.

Detection of the genetic polymorphism of human C2 (native protein and C2a fragment) by immunoblotting after polyacrylamide gel isoelectric focusing.

The polymorphism of the second component of human complement (C2) was studied by means of isoelectric focusing in polyacrylamide gels followed by immunoblotting with a specific antihuman C2 antibody. The polymorphism was studied in native C2 and in the C2a fragment obtained by activation of the classical pathway with heat-aggregated human IgG. Serum samples previously typed with the hemolytic overlay technique were analyzed. They comprised samples of homozygous C2*C, C2*B, C2*Q0, heterozygous C2*BC and C2*CQ0 individuals. The patterns obtained by immunoblotting corresponded to those obtained by the hemolytic overlay technique. As expected, the homozygous C2*Q0 sample (complement C2 deficiency) did not show any band pattern. The C2a fragment presented also a polymorphic variation which correlated exactly with the native C2 polymorphism. It appears thus that the polymorphic site of the C2 protein is carried by the C2a fragment for the C2*C and C2*B variants. In addition, this method is easier to perform than the common hemolytic overlay technique and the rare C2-deficient serum is not needed.