Chromosomal localisation of genes coding for human and mouse liver cytosolic cysteine dioxygenase

A panel of 22 hybrids was tested for the presence of the gene coding for human cysteine dioxygenase (CDO) by using human specific oligonucleotide primers in the polymerase chain reaction. Detection of human CDO completely correlated with the presence of human chromosome 5. A human total genome cosmid library was screened with a PCR product from the coding region of human CDO cDNA and the two positive clones identified were used in fluorescent in situ hybridisation (FISH) analysis on metaphase chromosome spreads. Fluorescent signals were seen on chromosome 5q22-23. Interspecific backcross mapping in the mouse indicated that Cdo, the mouse homologue of CDO, is situated in the central region of mouse chromosome 18 which shares a region of homology with human chromosome 5.

Mapping of the human homologs of the murine paired-box-containing genes

Mutations in paired-box-containing (Pax) genes have recently been found to be the primary lesions underlying human genetic disorders such as Waardenburg's Syndrome type 1 and mouse developmental mutants such as undulated (un), splotch (Sp), and small eye (Sey). In addition, PAX-6 is a strong candidate gene for aniridia in man. Eight independent Pax genes have been isolated in the mouse. All eight map to distinct regions of the mouse genome; they do not appear to be clustered in the same way as some groups of homeobox-containing genes. We have now mapped the human homologs of all eight of these genes; PAX genes are found on human Chromosomes (Chr) 1, 2, 7, 9, 10, 11, and 20.

The genes coding for phosphoenolpyruvate carboxykinase-1 (PCK1) and neuronal nicotinic acetylcholine receptor alpha 4 subunit (CHRNA4) map to human chromosome 20, extending the known region of homology with mouse chromosome 2

The mouse genes for cytosolic phosphoenolpyruvate carboxykinase-1 (Pck-1) and neuronal nicotinic acetylcholine receptor alpha 4 subunit (Acra-4) both map to distal chromosome 2 (Siracusa et al. 1989; Bessis et al. 1990). We have utilized Southern blot analysis on human/rodent somatic cell hybrids to map the human homologues of both of these genes, PCK1 and CHRNA4, to human chromosome 20.

Transposition, amplification, and divergence in the origin of the DNF15 loci, a polymorphic repetitive sequence family on chromosomes 1 and 3

The loci DNF15S1 and DNF15S2 are members of a small repetitive sequence family at discrete chromosomal locations, namely, 1p36 and 3p21, respectively. Studies of the structure, arrangement, and interrelations of the family suggest that the single copy on chromosome 3 is the original member and that this gave rise to the several members on chromosome 1 by transposition, partial duplication, and amplification. Several restriction fragment length polymorphisms have been discovered at the DNF15S1 locus and these have been assigned to the different subfamilies of the repeat at this locus. The existence of these RFLPs, and the nonallelic restriction site variation also found in this sequence family, suggests that transposition and amplification occurred as discrete events. We sequenced across the ancient junction between chromosomes 1 and 3 and noted features which might explain the mechanics of the transposition and amplification events.

Rhodanese isozymes in human tissues

An investigation of a range of tissue homogenates by various electrophoretic methods, followed by staining for specific enzyme activity, has revealed a series of isozymes of human rhodanese. Polyacrylamide gel isoelectric focusing provided the most data and rhodanese activity was found in all of the tissues examined. The simplest isozyme pattern was found in red cell lysates; liver homogenates generated the most complex pattern which included the 'red cell' forms together with a set of more basic 'tissue' isozymes. Variation in isozyme patterns thought to be attributable to storage changes affecting reactive sulphydryl residues was observed in 'red cell' rhodanese but no genetic variants of either 'red cell' or 'tissue' rhodanese were encountered in a study of material from the European population. We conclude that 'red cell' and 'tissue' rhodanese are determined by separate genes but more than one locus may be concerned with the synthesis of the heterogeneous 'tissue' isozymes.