Retrieval of human DNA from rodent-human genomic libraries by a recombination process

Human Alu repeat ("BLUR") sequences have been cloned into the mini-plasmid vector piVX. The resulting piBLUR clones have been used to rescue selectively, by recombination, bacteriophage carrying human DNA sequences from genomic libraries constructed using DNA from rodent-human somatic cell hybrids. piBLUR clones are able to retrieve human clones from such libraries because at least one Alu family repeat is present on most 15 to 20 kb fragments of human DNA and because of the relative species-specificity of the sequences comprising the Alu family. The rapid, selective plaque purification achieved results in the construction of a collection of recombinant phage carrying diverse human DNA inserts from a specific subset of the human karyotype. Subfragments of two recombinants rescued from a mouse-human somatic cell hybrid containing human chromosomes X, 10, 13, and 22 were mapped to human chromosomes X and 13, respectively, demonstrating the utility of this protocol for the isolation of human chromosome-specific DNA sequences from appropriate somatic cell hybrids.

Low incidence of deletion of the esterase D locus in retinoblastoma patients

Esterase D was quantitatively measured in the red blood cells from three patients from three separate kindreds who had abnormalities of chromosome 13. The esterase D activity was proportional to the number of copies of the q14 region of chromosome 13 present. These findings confirm published data localizing the esterase D gene to chromosome band 13q14, a region which is important in the etiology of retinoblastoma. Fifty-one additional retinoblastoma patients not known to have any chromosomal defect also underwent esterase D determination. In none of these patients did the esterase D measurement detect a 13q14 deletion. The normal esterase D levels in this series of 51 retinoblastoma patients suggest that deletion of an esterase D locus is infrequent in retinoblastoma patients. It must be noted that patients who are mosaics, with a 13q14 deletion in only a fraction of all somatic cells, could possibly have normal red blood cell esterase D levels. Further study is necessary to determine if esterase D determination of all retinoblastoma patients is a worthwhile clinical tool.

Isolation of human C-reactive protein complementary DNA and localization of the gene to chromosome 1

With a synthetic oligonucleotide mixture as probe, complementary DNA clones of C-reactive protein were isolated from an adult human liver complementary DNA library. The clones ranged in size from 700 to 1100 base pairs and were identified by partial DNA sequence analysis. One complementary DNA clone was used as a probe for hybridization with human-rodent DNA's isolated from somatic cell hybrids and bound to nitrocellulose filters (Southern blot analysis) to assign the human C-reactive protein gene to chromosome 1.

Isolation of DNA fragments from chromosome 13

A number of patients with retinoblastoma have a deletion of chromosome 13. Comparison of the deleted segments from different individuals reveals that all deletions involve chromosome band 13q14. This observation has lead to the hypothesis that in this region is a gene of genes important in the etiology of retinoblastoma. As a first step toward understanding those genes, the authors successfully isolated five DNA fragments from chromosome 13 using recombinant DNA techniques. The DNA fragments from chromosome 13 will be useful in identifying DNA polymorphic sites that are linked to the retinoblastoma locus tentatively assigned to 13q14. Such DNA polymorphisms will be important in the genetic counselling of families with retinoblastoma. These chromosome 13q14 fragments also may be useful in searching for microdeletions of 13q14.

Confirmation of the mapping assignment of human serum albumin to chromosome 4 using a cloned human albumin gene

The human albumin locus <i>(ALB</i>) is assigned to chromosome 4 by hybridization of a cloned human albumin gene (cDNA) probe to genomic DNA’s isolated from a panel of human-rodent somatic cell hybrids.

Human lysosomal genes: arylsulfatase A and beta-galactosidase

The segregation of human lysosomal arylsulfatase A (ARS-A) has been evaluated in 50 primary hybrid clones derived from four separate fusions involving WBCs from two unrelated individuals and three hamster cell lines. ARS-A was expressed in the hybrids as a dimeric molecule of very similar or identical subunits. The expression of this enzyme was concordant with that of mitochondrial aconitase (ACON-M), an isozyme assigned to chromosome 22, in all 50 clones and with chromosome 22 segregation in all but one of the 29 karyotyped hybrids. No other human chromosome cosegregated with 22 in these clones, suggesting that this enzyme is specified in hybrid cells by a locus (or loci) on a single chromosome. beta-Galactosidase (B-GAL) expression was analyzed with two different electrophoresis systems and with a number of cell extract preparation methods in 39 of the primary hybrid clones. The B-GAL isozyme expressed in these hybrid cells was concordant with the expression of glutathione peroxidase-1 (GPX-1), an isozyme assigned to chromosome 3, in all 39 clones and with the segregation of this chromosome in 97% of the 29 karyotyped hybrids. These observations substantiate the prior tentative assignments of an ARS-A locus to chromosome 22 and a B-GAL locus to chromosome 3 (Bruns et al., 1978a, b). The implications of the chromosome assignments of loci for 12 human lysosomal enzymes for the cellular assembly of these organelles are discussed.

Assignment of a Mus musculus gene for triosephosphate isomerase to chromosome 6 and for glyoxalase-I to chromosome 17 using somatic cell hybrids

Chinese hamster X mouse hybrid cells segregating mouse chromosomes have been used to assign a gene for triosephosphate isomerase (TPI-1, EC 5.3.1.1, McKusick No. 19045) to mouse chromosome 6, and a gene for Glyoxalase-I (GLO-1, EC 4.4.1.5, McKusick No 13875) to mouse chromosome 17. The genes for TPI-1 and lactate dehydrogenase B are syntenic in man and probably so in the dog. It is therefore likely that they are syntenic also in the mouse. It is of interest then that there is a mouse gene, Ldr-1, on chromosome 6 that regulates the level of LDH B subunits in mouse erythrocytes. The locus for GLO-1 is closely linked to the major histocompatibility complex in man. Since the major histocompatibility complex in the mouse is present on chromosome 17, this locus and the Glo-1 locus are syntenic in the mouse as well. This finding adds to the number of autosomal gene pairs which are syntenic in both mouse and man and reinforces the belief that there is considerable conservation. of linkage groups during evolution.

Adenylate kinase 2, a mitochondrial enzyme

The subcellular compartmentalization of the isoenzymes of ATP:AMP phosphotransferase (adenylate kinase) was analyzed in HeLa cells, RAG cells, and RAG-human hybrids that express human AK-2. In HeLa cells and in the hybrids, human AK-2 was present in a mitochemical fraction prepared from cell extracts and in mitochondria purified by density gradient centrifugation. Human AK-1 was, as expected, distributed in the soluble cytoplasmic fraction of the cells. The rodent isozymes which are homologous to human AK-1 and AK-2 have been determined.

Expression of alpha-D-mannosidase in man-hamster somatic cell hybrids

Two types of alpha-D-mannosidase isozymes are present in human white blood cells, human diploid fibroblasts, and HeLa cells. One of these (the S isozyme) constitutes the major alpha-D-mannosidase of the human cells, has a pH optimum of 4.4, and is associated with lysosomes. The other (the F isozyme) is most active at pH 6, is acid labile, and is located in the soluble portion of the cytoplasm. The expression of human lysosomal alpha-D-mannosidase was examined in man-hamster hybrid clones, and was found to be concordant with that of phosphohexose isomerase in 54 of 55 primary clones. A locus specifying human lysosomal alpha-D-mannosidase has therfore been assigned to chromosome 19.

Human glyceraldehyde-3-phosphate dehydrogenase in man-rodent somatic cell hybrids

The human enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) forms heteropolymers with the rodent enzyme in man-rodent somatic cell hybrids. A gene specifying GAPDH is syntenic with the genes specifying the glycolytic enzymes triosephosphate isomerase (TPI) and lactate dehydrogenase B (LDH-B). The synteny of GAPDH, TPI, and LDH-B is the first evidence for the syntenic association of human genes that specify enzymes of the Embden-Meyerhof glycolytic pathway.

Expression of the human adenylate kinase isozymes, phosphopyruvate hydratase, 6-phosphogluconate dehydrogenase, and phosphoglucomutase-1 in man-rodent somatic cell hybrids

The expression of the adenylate kinase isozymes and of phosphopyruvate hydratase was studied in man-mouse and man-hamster hybrid clones. Concordant segregation of the loci coding for AK-2 and PPH was observed in 54 of 55 primary hybrid clones, and these loci were demonstrated to be synthetic with the loci specifying PGM-1 and PGD. The pattern of expression of the four enzymes in discordant clone suggests the gene order 1pter-(PGD, PPH)-AK-2-PGM-1-centromere. In addition, AK-1 was found to be expressed independently of AK-2.

Human mitochondrial NADP-dependent isocitrate dehydrogenase in man-mouse somatic cell hybrids

Human mitochondrial NADP-dependent isocitrate dehydrogenase (IDH-2) is expressed in man-mouse somatic cell hybrids as a dimeric molecule. The gene specifing this enzyme was observed to be syntenic with the mannose phosphate isomerase locus in the 56 primary man-mouse clones in this series. The human IDH-2 locus, therefore, may be assigned to chromosome 15.

Human acid phosphatase in somatic cell hybrids

The human enzyme, lysosomal acid phosphatase ACP2, is expressed in nan-rodent somatic cell hybrids as a dimeric molecule. The human-rodent heteropolymer, as well as the human and rodent homopolymer, is associated with lysosomes in these cells. The genes specifying lysosomal acid phosphatase ACP(2) and LDH A are syntenic.

The erythroid cells and haemoglobins of the chick embryo

The changes in the types of erythroid cells produced during embryogenesis of the chick have been correlated with the changes in the types of haemoglobins found in the embryo. Primitive erythroid cells constitute the only red blood cells of 2- to 5-day embryos. The first recognizable immature definitive erythroid cells appear in the embryonic circulation at 5 to 6 days and progressively replace the primitive cells, such that by 14 to 16 days the primitive cells constitute less than 1 % of the circulating erythroid cells. Primitive erythropoiesis is strikingly different from definitive erythropoiesis. At any one time point between 2 and 16 days, all of the isolated primitive cells appear, by morphological criteria, to be at the same stage of maturation, and, although variation in cell size is observed, for an individual maturation stage, the small cells are not more mature than the medium-size cells, nor are the large cells less mature than the medium or small cells. Maturing primitive erythroid cells undergo the progressive changes in cell structure characteristic of erythroid maturation in mammalian erythropoietic systems, but do so as a uniform cell population. Haemoglobin, isolated from primitive erythroid cells of 2- to 5-day embryos, shows two components on polyacrylamide gel electrophoresis, haemoglobin E and haemoglobin P. The haemoglobin E/P ratio is constant in lysates from 2- to 5-day embryos. A t 6 to 7 days when the first haemoglobinized immature definitive erythroid cells appear in the embryonic circulation, two new haemoglobin components are observed in lysates of erythroid cells. These two new haemoglobin components are electrophoretically and immunologically identical to the two haemoglobin components of adult chickens, haemoglobins A and D. As the definitive erythroid cells replace the primitive erythrocytes in the embryonic circulation, the haemoglobins A and D increase in amount and replace haemoglobin P. Haemoglobin P cannot be detected immunologically in erythroid cell lysates from 16-day embryos which contain less than 1 % primitive cells. In erythroid cell lysates from late embryos, which contained few, if any, primitive erythrocytes, a minor haemoglobin, electrophoretically similar to haemoglobin E on pH 10.3 polyacrylamide gels, is consistently observed. This component differs from haemoglobin E on pH 8.9 polyacrylmide gels, on Sephadex G-100 columns, on polyacrylamide gels of different porosities, and shows a reaction of only partial identity with haemoglobin E by two-dimensional immunodiffusion. This haemoglobin component, haemoglobin H, is detectable electrophoretically in lysates from 12-day embryos and immunologically in lysates from 8-day embryos. Haemoglobin H has not been observed in adult chickens. The switch from the production of primitive to definitive erythroid cells during development of the chick embryo is associated with the initiation of synthesis of three new haemoglobins, the two adult haemoglobins and haemoglobin H. The haemoglobin D /A ratio of adult chicken haemoglobin, determined from the ratio of gel scan peak masses, is 0.30. When haemoglobins D and A first appear in erythroid cell lysates from 6- to 7-day embryos, the haemoglobin D /A ratio is about 0.9. T he D/A ratio of lysates falls to 0.5 by 16 to 18 days, a time when 99 % of the erythroid cells of the embryo are mature definitive erythrocytes. However, the haemoglobin D /A ratio of lysates from late embryos and young chicks of 0.5 to 20 days of age is consistently greater than that of adult chicken haemoglobin. Definitive erythrocytes of chick embryos and young chicks appear to differ from definitive cells of adult chickens in at least two ways: the presence of haemoglobin H and the higher haemoglobin D/A ratio.