Jennifer M. Parrington

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.

Overrepresentation of chromosome 12p sequences and karyotypic evolution in i(12p)-negative testicular germ-cell tumors revealed by fluorescence in situ hybridization

Human testicular germ-cell tumors (TGCTs) comprise a heterogeneous group of solid neoplasms. These tumors are characterized by the presence of a highly specific chromosomal abnormality, i.e., an isochromosome of the short arm of chromosome 12. At present, this i(12p) chromosome is found in more than 80% of TGCTs. Isochromosome 12p has also been observed in some ovarian and extragonadal germ cell tumors. In the remaining so-called i(12p)-negative TGCTs other abnormalities involving chromosome 12, mainly 12p, can be found. In order to establish whether 12p abnormalities other than i(12p) are a common phenomenon in TGCTs, a panel of 11 i(12p)-negative tumors was investigated using multicolor fluorescence in situ hybridization. All TGCTs examined appeared to contain chromosomal abnormalities involving 12p, resulting in a distinct overrepresentation of short arm sequences. In addition, indications were obtained for a clonal evolution in one of the tumors. Our data suggest that the occurrence of 12p abnormalities is a common phenomenon in i(12p)-negative TGCTs and that these abnormalities, analogous to i(12p), may contribute to the process of tumor development.

Unscheduled DNA synthesis, u.v.-induced chromosome aberrations adn SV40 transformation in cultured cells from xeroderma pigmentosum

Xeroderma pigmentosum (XP) is a rare autosomal recessive skin disease (El-Hefnawi, Maynard Smith & Penrose, 1965) characterized by extreme sensitivity to sunlight and a greatly increased susceptibility to carcinomas and melanomas of the skin. A severe deficiency or complete absence of DNA repair replication following 2537A. U.V. irradiation has been demonstrated in both cultured fibroblasts (Cleaver, 1968; Bootsma, Mulder, Pot & Cohen, 1970) and lymphocytes (Burk, Lutzner & Robbins, 1969) from these patients. Recent work has suggested that the initial step in the repair mechanism the recognition and excision of thymine dimers, is deficient in xeroderma cells (Setlow, Regan, German & Carrier, 1969; Cleaver, 1969; Cleaver & Trosko, 1970). The retention of pyrimidine dimers in the DNA of skin cells thus directly or indirectly predisposes the cells to neoplastic change. Normal human cells can be photosensitized to long-wavelength U.V. radiation by treatment with the furocoumarin trisoralen (Trosko & Isoun, 1971). Pathak & Kramer (1969) have demonstrated that furocoumarins form C 4-cycloaddition products with DNA, following prolonged irradiation, and postulated that this reaction is an important mechanism in photosensitization. Trosko & Isoun (1971) showed that cells treated with trisoralen and 3600A. wavelength light, showed markedly reduced DNA synthesis. These workers also demonstrated that trisoralen and 3600 d irradiation did not inhibit excision of pyrimidine dimers formed by short-wavelength U.V. radiation (2637 A), but they did not investigate repair synthesis following exposure of the photosensitized cells to 3600 d. U.V. Studies in bacteria, however, have suggested that DNA excision repair may occur (Igali, Bridges, Ashwood-Smith & Scott, 1970). A liquid scintillation assay, similar to that developed for leucocyte cultures (Robbins, Burk & Levis, 1970) has been used here to measure the amount of u.v.-stimulated thymidine uptake of normal and xeroderma fibroblasts. In this way the level of repair in different xeroderma patients can be compared. The fibroblasts of three xeroderma patients have been cultured and the amount of unscheduled DNA synthesis after short-wave U.V. (2537 B.) estimated both by autoradiography and liquid-scintillation counting. The same techniques have been used to find out whether there is any measurable repair synthesis after treatment with trisoralen and long-wave U.V. The liquid-scintillation assay technique has also been used to determine whether there is any change in the level of repair in fibroblasts from a xeroderma patient after these cells have undergone viral transformation.

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.

The genetics of peptidase C in man.

Several distinct peptidases, which may be differentiated by their electrophoretic characteristics, their pattern of substrate specificity and their molecular size, have been demonstrated in human cells (Lewis & Harris, 1967, 1969a; Rapley, Lewis & Harris, 1971). They are referred t o as peptidases A, B, C, D, E, F and S and are thought to be determined by separate gene loci. Genetically determined variants of Pep A, B and D in European, Indian and Negro populations and in Australian aborigines have been described (Lewis & Harris, 1967; Lewis, Corney & Harris, 1968; Lewis & Harris, 1969b; Blake et al. 1970). Genetic variation in Peptidase C (Pep C) has until now only been reported in a group of Babinga pygmies (Santachiara Benerecetti, 1970). She found 5 examples out of 261 random blood samples in which an additional band of Pep C activity appeared, with a lower mobility than the usual Pep C band, and two examples in which the normal band was entirely replaced by the slow band. She also found 11 examples of Pep C absence although Pep A activity remained. On the basis of this and limited family studies she postulated three autosomal alleles, Pep C1, Pep C2 and Pep CO, the product of Pep Co being undetectable electrophoretically. We present here evidence for genetic variation of Pep C in European, Indian and Negro populations, and discuss the relationship of the variants seen with those described by Benerecetti.

Linkage relationships between the three phosphoglucomutase loci PGM1, PGM2 and PGM3

1. Phosphoglucomutase phenotypes have been studied in several generations of the family of an individual heterozygous at each of the three loci, PGM1, PGM2, and PGM3.

Development and characterization of cisplatin-resistant human testicular and bladder tumour cell lines

Cisplatin-resistant cells were derived in vitro from a human bladder carcinoma cell line (RT112) and a testicular tumour cell line (SuSa) by continuous exposure to increasing concentrations of cisplatin for 14 and 11 months, respectively. Both resistant cell lines had a four-fold level of resistance relative to their parental cell lines, comparing the cisplatin concentration to inhibit colony forming ability by 70%. These levels of resistance were retained in the absence of cisplatin for at least 3 months. In each case, four-fold fewer micronuclei were produced in the resistant lines by the same cisplatin concentrations. Cross-resistance to carboplatin and methotrexate was observed in both resistant cell lines, but neither line was resistant to doxorubicin. Isozyme and DNA analysis with hypervariable probes confirmed the origin of each resistant cell line from its parental line. Population doubling times and intermitotic times were similar in each of the pairs of cell lines. Karyotyping showed that the resistant cell lines had gained and lost marker chromosomes, but there were no changes common to both resistant cell lines.

Anomalous cellular proliferation in vitro associated with Huntington's disease

SummaryDetailed growth analyses of cultured skin fibroblasts from two patients with Huntingtons Disease (HD) were compared with those from controls matched for age and sex. In contrast to control cells, HD fibroblasts plated more efficiently at the low seeding densities used. Subsequent exponential growth of HD cultures was more stable towards routine trypsinisation than that of controls. However, the most striking feature of HD cultures was their ability to grow to significantly higher cell saturation densities. Experiments with trypsinised and untrypsinised cultures imply an inherent alteration in the HD cell membrane.

Patau's syndrome with D1 duplication‐deficiency derived from a maternal D group pericentric inversion

Pericentric inversions are detectable in somatic cells only if they result in a shift in centromere position which substantially alters the chromosome morphology so that the inverted chromosome can be distinguished from the other members of the group. For this reason, large-scale surveys are bound to give an underestimate of the extent of chromosome inversions in man. The population studies available suggest that detectable inversions are relatively infrequent and may show no adverse effect in individual carriers or their offspring (Court Brown et al. 1966; Jacobs et al. 1967). Inversions have also been ascertained through a wide variety of phenotypically abnormal individuals, but few of these have been causally implemented in the original disorders. They include two cases of an inversion in chromosome no. 1 (Lele, Dent & Delhanty, 1965), four involving chromosome no. 2 (Carr, 1962; De Grouchy et al. 1963; Miller, 1966; Breg, 1966), one involving a group-B chromosome (Morishima, Liu & Grumbach, 1964), four separate families with inverted C-group chromosomes (Jacobs et al. 1967 ; Ferguson-Smith, 1966) and two with D-group inversions (Cohen, Capraro & Takagi, 1967 ; Crandall & Sparkes, 1970). Other morphologically abnormal autosomes have been described which might represent either pericentric inversions or small duplications (De Grouchy et al. 1965; Prats & Moragas, 1967; Chandra & Hungerford, 1963; Gray, Mutton & Ashby, 1962; Ellis, Marshall & Penrose, 1962). The family presented here represents one of the few instances where a maternal autosomal pericentric inversion is thought to have given rise to duplication-deletion gametes resulting in congenitally malformed offspring.

Elucidation of a pericentric inversion of a D-group chromosome in the mother of a child with Patau's syndrome

The mother of a child with Pataus syndrome has an inversion of chromosome 13. The karyotype is designated 46, XX, inv (13) (p13q21). It is deduced that the deceased child had the karyotpye 46, XY, rec(13), dup q, inv(13) (p13q21).