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M Zollo

Publications and source records attributed to M Zollo.

33 records · Page 2Linked to original sources
PubMed1996

Identification and mapping of human cDNAs homologous to Drosophila mutant genes through EST database searching.

Cross-species comparison is an effective tool used to identify genes and study their function in both normal and pathological conditions. We have applied the power of Drosophila genetics to the vast resource of human cDNAs represented in the expressed sequence tag (EST) database (dbEST) to identify novel human genes of high biological interest. Sixty-six human cDNAs showing significant homology to genes causing Drosophila mutant phenotypes were identified by screening dbEST using the "text string' option, and their map position was determined using both fluorescence in situ hybridization (FISH) and radiation hybrid mapping. Comparison between these genes and their putative partners in Drosophila may provide important insights into their function in mammals. Furthermore, integration of these genes into the transcription map of the human genome contributes to the positional candidate approach for disease gene identification.

Amino Acid Sequence↗
PubMed1996

Long-range sequence analysis in Xq28: thirteen known and six candidate genes in 219.4 kb of high GC DNA between the RCP/GCP and G6PD loci.

DNA comprising 219 447 bp was sequenced in nine cosmids and verified at > 99.9% precision. Of the standard repetitive elements, 187 Alus make up 20.6% of the sequence, but there were only 27 MERs (2.9%) and 17 L1 fragments (1.6%). This may be characteristic of such high GC (57%) regions. The sequence also includes an 11.3 kb tract duplicated with 99.2% identity at a distance of 38 kb. The region is 80-90% transcribed and 12.5% translated. Thirteen known genes and their exon-intron borders are all accurately predicted at least in part by GRAIL programs, as are six additional genes. From centromere to telomere, the orientation of transcription varies among the first eight genes, then runs centromeric to telomeric for the next five, and is in the opposite sense for the last six. Eighteen of the 19 genes are associated with CpG islands. Two islands are exact copies in the 11.3 kb repeat units, and could thus give rise to double dosage levels of an X-linked gene. Another island is associated with two genes transcribed in opposite directions. From the sequence data, three genes and their exon structure are inferred. One of them, previously associated with HEX2, is shown to be a different gene unrelated to hexokinases; a second gene, previously known by an EST, is plexin, from its 65.5% identity with the Xenopus analog; and a third is a subunit of a vacuolar H-ATPase, and is named VATPS1.

Base Sequence↗
PubMed1995

Sequence and gene content in 52 kb including and centromeric to the G6PD gene in Xq28.

A cosmid containing 36.4 kb of high GC human DNA centromeric to the G6PD gene has been analyzed. The sequence was 99.9% precise, based on the comparison of 4.3 kb that overlaps an earlier analysis of 20.1 kb containing G6PD. Properties of the entire 52 kb region that may be characteristic of high GC portions of the genome include a very high density of sixty-two half or full Alu sequences, or 1.2/kb, and an absence of L1 sequences. Other highly repetitive sequences include 11 MER sequences, one of them interrupted at two positions by groups of 3 Alu elements. In segments of unique sequence, computer-aided analysis predicted three possible genes, one of which has thus far been confirmed by the recovery of a corresponding cDNA, both by a direct hybridization method and by a PCR-based method based on a primer pair inferred from the genomic sequence. The cDNA has been sequenced, and is completely concordant with counterpart genomic sequence; it has no resemblance to any previously described gene.

Base Sequence↗
PubMed1993

Use of a sensitive fluorescent intercalating dye to detect PCR products of low copy number and high molecular weight.

The ability to routinely and specifically amplify and detect PCR products ranging in size from < 1 to > 10 kb, regardless of target template sequence or structure, would facilitate several tasks in human genome research. Generation of a wide size range of PCR products would potentially expedite isolation of uncloned DNA (gaps) represented in physical maps and provide a means for maintaining order and orientation of closely linked loci during analysis. Long-range PCR offers an alternative to isolation of genomic or cDNA clones from tissues or species where appropriate libraries are unavailable. This methodology also provides a powerful strategy to pursue directed transposon-based mapping and sequencing of templates of 100 kb or greater. Further development of basic PCR technology has been necessary in order to make it feasible to use large DNA targets as primary templates for genome analysis. Application of these extended PCR capacities would potentially save time, materials, and cost.

Bacteriophage lambda↗
PubMed1993

Sequence of mouse glucose-6-phosphate dehydrogenase cDNA.

A full-length mouse glucose-6-phosphate dehydrogenase (G6PD) cDNA has been isolated and sequenced, and the evolutionary conservation of many portions of the sequence has been verified by comparison with that of human and other sources.

Amino Acid Sequence↗
PubMed1991

Deletion of the distal short arm of the X chromosome (Xp) in a patient with short stature, chondrodysplasia punctata, and X-linked ichthyosis due to steroid sulfatase deficiency.

We observed a boy with short stature, chondrodysplasia punctata, ichthyosis, and a terminal deletion of Xp. Steroid sulfatase deficiency was demonstrated in the patient's fibroblasts. Molecular analysis showed a deletion of the entire steroid sulfatase gene. This case represents another example of a contiguous gene syndrome in which the co-deletion of adjacent genes on a chromosome is responsible for a complex phenotype.

Abnormalities, Multiple↗
PubMed1990

Screening for steroid sulfatase (STS) gene deletions by multiplex DNA amplification.

Deletions are the most common molecular defect in steroid sulfatase (STS) deficiency. We describe the application of multiplex DNA amplification, by polymerase chain reaction, for deletion screening in patients with STS deficiency (STS-PCR). Genomic DNA from 38 unrelated patients was amplified using two sets of primers, corresponding to the 5' and the 3' ends of the STS gene. The analysis of the amplified products was always consistent with the results obtained by Southern analysis. This method represents a sensitive fast non-radioactive test for detecting STS gene deletions.

Arylsulfatases↗
PubMed1989

Molecular characterization of a gene of the 'EGF family' expressed in undifferentiated human NTERA2 teratocarcinoma cells.

A novel human gene, encoding a 188 amino acid polypeptide that contains a region similar to that of the epidermal growth factor, has been isolated. The gene, expressed in undifferentiated human and mouse teratocarcinoma cells, is shut off after inducing the cells to differentiate by treatment with retinoic acid. Introduction of the cDNA under the control of a viral LTR induces transformation of NIH3T3 cells.

Amino Acid Sequence↗
PubMed1989

Molecular heterogeneity of steroid sulfatase deficiency: a multicenter study on 57 unrelated patients, at DNA and protein levels.

Steroid sulfatase (STS) deficiency is the biochemical defect of X-linked ichthyosis (XLI), one of the most common X-linked disorders. We studied 57 European unrelated patients affected by STS deficiency. Twenty-eight patients were from Italy, 24 from the United Kingdom, 4 from The Netherlands, and 1 from Denmark. In two families XLI was associated with Kallmann syndrome (hypogonadotropic hypogonadism and anosmia). STS enzymatic activity was profoundly deficient in all cases. Direct DNA analysis, using cDNA and genomic probes from the STS gene and linked regions, demonstrated heterogeneity of the molecular defect. Forty-eight patients (84%) showed a deletion of the STS gene. In 44 cases the deletion also involved the STS flanking locus DXS237. In 1 patient a partial deletion of the STS gene was detected and in 9 patients no evidence of deletion was found. Locus DXS31 (probe M1A), previously mapped to Xp22.3-pter, was not deleted either in 24 patients with X-linked ichthyosis or in two families with X-linked ichthyosis associated with Kallmann syndrome. Consequently, the following loci order could be suggested: telomere--DXS31--(DXS237, STS)--Kallmann--centromere. Immunoblotting experiments, performed using anti-STS polyclonal antibodies, revealed the absence of cross-reacting material to STS in all cases tested, including 4 patients without evidence of deletions.

Arylsulfatases↗
PubMed1987

Molecular studies of marsupial X chromosomes reveal limited sequence homology of mammalian X-linked genes.

To explore the extent to which the X chromosome has been conserved during mammalian evolution, we compared six loci that are X-linked in the human genome with the corresponding genes of the North American marsupial, the Virginia opossum (Didelphis virginiana). Our analysis shows that in the opossum genome there are sequences highly homologous to those of human cDNAs for housekeeping genes, glucose-6-phosphoribosyltransferase (HPRT), phosphoglycerate kinase A (PGK1), and alpha-galactosidase A (GLA). However, ornithine transcarbamylase and blood clotting Factor IX--tissue-specific genes that are X-linked in eutherians mammals--have no highly conserved homologs in the marsupial genome. By cloning opossum G6PD and HPRT, we found that these genes are X-linked in the opossum and that homologous sequences are limited to coding regions. As all genomic fragments hybridizing with the human GLA probe show dosage effects, it is likely that the opossum counterpart is X-linked. Finally, the pattern of hybridization suggests that the autosomal pseudogenes of HPRT and PGK1 in the opossum have remained highly homologous to the human X-linked genes.

Animals↗
PubMed1987

Identification of incomplete coding sequences for steroid sulphatase on the human Y chromosome: evidence for an ancestral pseudoautosomal gene?

A cDNA clone (p422) containing about 200bp of coding sequences for steroid sulphatase (STS) has been isolated from a lambda gt11 expression library by antibody screening and has been assigned by mapping with a somatic cell hybrid panel and by in situ hybridization to Xp22.3; a localization coincident with the previously identified locus for STS expression. Although no significant hybridization of this clone to the Y chromosome was observed, p422 has been used to isolate a longer cDNA clone and genomic sequences which do recognize Y-specific restriction fragments. An abbreviated STS gene has been localized to Yq11.2. The coding sequences for the human enzyme shows little homology to sequences in mice.

Animals↗
PubMedDate not supplied

No evidence for SEL1L as a candidate gene for IDDM11-conferred susceptibility.

BACKGROUND: The SEL1L gene is located on human chromosome 14q24.3-31 close to D14S67 which has been previously proposed to be a type 1 diabetes mellitus locus (IDDM11). Sel-1 is a negative regulator of the Notch signalling pathway and SEL1L is selectively expressed in adult pancreas and islets of Langerhans. This suggests that SEL1L may be a candidate gene for IDDM11. METHODS: We have analysed two newly identified CA-repeat polymorphisms within the genomic sequence of the SEL1L locus for association with type 1 diabetes mellitus (T1DM) in 152 Danish T1DM-affected sib-pair families and in 240 Sardinian families (229 simplex and 11 sib-pair families). RESULTS: No evidence for association of the two SEL1L markers with T1DM was observed in either the Danish or the Sardinian families. We have also used allelic sharing methods to analyse linkage with T1DM in the IDDM11 region using the same markers and the Danish collection of affected sib-pair families. No evidence of linkage was observed (Z(max)=0.86). CONCLUSION: Although several lines of evidence suggest that SEL1L might be a candidate for IDDM11-conferred susceptibility to T1DM the present study does not support this hypothesis.

Alleles↗
PubMedDate not supplied

A new candidate region for the positional cloning of the XLP gene.

X-linked lymphoproliferative disease (XLP) is an inherited immunodeficiency characterised by selective susceptibility to Epstein-Barr virus and frequent association with malignant lymphomas chiefly located in the ileocecal region, liver, kidney and CNS. Taking advantage of a large bacterial clone contig, we obtained a genomic sequence of 197620 bp encompassing a deletion (XLP-D) of 116 kb in an XLP family, whose breakpoints were identified. The study of potential exons from this region in 40 unrelated XLP patients did not reveal any mutation. To define the critical region for XLP and investigate the role of the XLP-D deletion, detailed haplotypes in a region of approximately 20 cM were reconstructed in a total of 87 individuals from 7 families with recurrence of XLP. Two recombination events in a North American family and a new microdeletion (XLP-G) in an Italian family indicate that the XLP gene maps in the interval between DXS1001 and DXS8057, approximately 800 kb centromeric to the previously reported familial microdeletion XLP-D.

Base Sequence↗