L. F. West

Human myosin heavy chain genes assigned to chromosome 17 using a human cDNA clone as probe.

A cDNA clone complementary to the mRNA encoding human myosin heavy chain has been isolated from a human fetal skeletal muscle cDNA library. A 600 base pair fragment of the inserted human cDNA has been used as probe in the Southern analysis of DNA from panels of rat/human and mouse/human somatic cell hybrids. All the sequences detected by this probe have been mapped to chromosome 17 in the region 17pter → 17p11. There was no evidence for MHC sequences on any other chromosome.

A cytochrome P-450 gene family mapped to human chromosome 19.

We have recently isolated a cloned cDNA coding for a cytochrome P‐450 of human liver microsomal membranes, which corresponds to a major phenobarbital‐inducible cytochrome P‐450 of rat liver. This human cytochrome P‐450 is encoded by a member of a multigene family. DNA extracted from a panel of 12 independent human‐rodent somatic cell hybrids was analysed by Southern blot hybridization with the cloned cDNA. The results indicate that all components of this cytochrome P‐450 gene family are located on chromosome 19. Evidence from hybrids derived from an individual carrying a balanced translocation suggests a regional localization of 19p13.2→qter. Analysis of human metaphase chromosomes by in situ hybridization localizes this cytochrome P‐450 gene family further to the long arm of chromosome 19 in the region q13.1→qter. We propose the designation P450PB for this locus.

The gene for human complement component C9 mapped to chromosome 5 by polymerase chain reaction

The gene for human complement component C9 has been mapped to chromosome 5. This was achieved by using a novel application of the polymerase chain reaction to amplify specifically the human C9 gene on a background of rodent DNA in somatic cell hybrids. The assignment to chromosome 5 was confirmed by in situ hybridization to human metaphase chromosomes, giving a regional localization of 5p13.

Chromosome assignment, biochemical and immunological studies on a human aldehyde dehydrogenase, ALDH3

The biochemical properties of ALDH isozymes have been examined in human tissues and one set, designated ALDH3, has been studied in detail. These components occur at highest levels in lung and stomach, but were not expressed in fetal tissues, or in blood, hair roots and fibroblasts. The ALDH3 isozymes show optimal activity with benzaldehyde and can use either NAD or NADP as cofactor. Antiserum against a partially purified ALDH3, from stomach, selectively precipitates this isozyme from human tissues and selectively recognizes an homologous component in the rat. Human and rodent ALDH3 were not immunoprecipitated by anti‐ALDH1 or anti‐ALDH2 antisera. High levels of expression were found in human‐rodent hybrids, constructed using rat hepatoma cells, and these hybrids were used to assign the human ALDH3 gene to chromosome 17.

Loss of heterozygosity in hypotriploid cell cultures from testicular tumours

SummaryWe have established cell lines with a hypotriploid chromosome number from four testicular tumours. Each line had at least one Y chromosome and most of the informative centromere and enzyme markers were heterozygous implying that the tumours originated from germ cells before the first meiotic division. The small metacentric marker chromosome (i12p), specific for testicular tumours, was present in all tumour cell lines and up to three copies were found in some lines. Rearrangements of chromosome 1 and 11 were each found in three out of four tumours. The rearrangements of chromosome 1 all resulted in duplication of 1q and deletion of short-arm material from the same chromosome giving loss of heterozygosity for enzyme markers on 1p. Loss of satellite material from chromosome 13 and the centromere region of chromosome 9 were found in single cases. This study shows that even where the chromosome number of tumour cells is near triploid, regions of the genome can be deleted. The chromosomes most frequently involved in rearrangements, 1, 11, and 12 all contain sites of ras oncogenes and it is suggested that loss of normal alleles could result in homozygosity for mutant oncogenes which may play a part in tumour progression.

Regional localization of carbonic anhydrase genesCA1 andCA3 on human chromosome 8

The human carbonic anhydrase isozymes represent a family of homologous proteins which are important in respiratory function, fluid secretion, and maintenance of cellullar acid-base homeostasis. Using somatic cell genetic techniques we have mapped two of the CA genes (CA1and CA3)to human chromosome 8. In situ hybridization data demonstrates that both CA1and CA3map to the same region (q13–q22) of chromosome 8.

Assignment of the human nicotinic acetylcholine receptor genes: the alpha and delta subunit genes to chromosome 2 and the beta subunit gene to chromosome 17

The chromosomal assignments of the genes coding for the alpha, beta and delta subunits of the human nicotinic acetylcholine receptor have been determined from a panel of somatic cell hybrids and by direct in situ hybridization. The results localize CHRNA to 2q24‐2q32. CHRNB to 17p11 17p12, and CHRND to chromosome 2q33‐2qter.

The gene for human αaL-lactalbumin is assigned to chromosome 12q13

A cDNA clone complementary to the mRNA encoding human αaL‐lactalbumin (ALA) has been used as a probe in the analysis of DNA from panels of rodent/human somatic cell hybrids. The presence of the ALA gene correlates with the presence of chromosome 12. In situ hybridization localizes the ALA gene to 12q13.

Chromosome analysis of parallel short-term cultures from four testicular germ-cell tumors

Cytogenetic analysis has been carried out on 17 parallel short-term cultures from four malignant testicular teratomas of intermediate differentiation (MTI), two of them combined with seminomas. Clonal development was seen in three tumors, with most of the variation involving different rearrangements of chromosome 1. Two copies of the i(12p), characteristic of testicular germ-cell tumors, were present in the two tumors with yolk sac elements, a single i(12p) and a 12q- were found in an MTI that had metastasized, and a rearrangement of chromosome 12 containing centromeric chromatin from chromosome 18 was found instead of the i(12p) in a mixed tumor. A 13p+ marker containing Q-negative material was seen in two of the tumors, with a der(7)t(Y;7) in one. Chromosomes 1, 3, 6, 7, 8, 12, 17, and X were invariably overrepresented either as complete or partial trisomies, and chromosomes 4, 5, 13, and 18 were underrepresented in all four tumors, strengthening the idea that tumor suppressor genes on the latter four chromosomes, all of which show some loss of heterozygosity with DNA markers, may be important in tumor progression.

The assignment of the human gene coding for complement C5 to chromosome 9q22-9q33

The presence or absence of the human gene for the fifth component of complement (C5) was analysed in 19 human‐rodent hybrid cell lines by hybridization to a radiolabelled probe derived from a human C5 cDNA clone. The segregation of C5 in these hybrids suggested that the gene is localized on chromosome 9, in the region 9q21‐9qter. In situ hybridization refined the assignment of C5 to chromosome 9q22‐33.