Search PubMed⌕ Search

Biomedical subjects

G N Wilson

Publications and source records attributed to G N Wilson.

88 records · Page 5Linked to original sources
PubMed1983

Trisomy 9 mosaicism: another etiology for the manifestations of Goldenhar syndrome.

A term female infant with intrauterine growth retardation and multiple congenital anomalies had trisomy 9 mosaicism in blood and skin fibroblast cultures. Anomalies typical of Goldenhar syndrome included an epibulbar dermoid, auricular malformation, hemifacial microsomia, vertebral anomalies, cardiac defects, pulmonary hypoplasia, renal hypoplasia, and limb defects. This case emphasizes the value of chromosomal evaluation of lateral asymmetry, the heterogenous etiology of Goldenhar syndrome, and the variable phenotypes produced by trisomy of large autosomes.

Chromosomes, Human, 6-12 and X↗
PubMed1982

The phenotype of ring chromosome 3.

A male child with mental retardation and poor growth was found to have a 46,XY,r3 (p26 leads to q29) karyotype in 92% of his peripheral lymphocytes and 90% of his cultured fibroblasts. Comparison of this patient's dysmorphic features with previously reported cases of ring 3 or deletion 3p suggests a clinical syndrome derived mainly from deletion of 3p26 leads to pter. The syndrome consists of mental retardation, pre- and postnatal growth retardation, microcephaly, hypertonia, digital anomalies, and a characteristic facies with ptosis, epicanthal folds, broad nasal root, down-turned corners of the mouth, and dysplastic ears.

Abnormalities, Multiple↗
PubMed1982

Structure and variation of human ribosomal DNA: the external transcribed spacer and adjacent regions.

A group of human ribosomal DNA (rDNA) recombinants that include the probable site for initiation of transcription have been examined for sequence polymorphism. A detailed restriction map of one rDNA insert was constructed using plasmid subclones and end-labeled segments. Comparison of 16 similar rDNA inserts by restriction and heteroduplex analysis demonstrated striking conservation of the external transcribed spacer and 18S gene regions, but defined a region where restriction sites for the enzymes Sma I, Hpa II, and Hha I become frequent or variable. This region extends for about 400--800 base pairs (bp) at the left end of the rDNA insert and is postulated to contain nontranscribed spacer sequences. The use of cloned rDNA segments as probes for the restriction analysis of genomic rDNA has demonstrated certain fixed sites in the nontranscribed spacer that do not vary significantly among different individuals or tumor cell lines. In contrast, restriction with the enzyme Sal I reveals several variable fragments, one of which has been found only in a retinoblastoma cell line.

Base Composition↗
PubMed1981

Structure and variation of human ribosomal DNA: molecular analysis of cloned fragments.

Eco-RI-A fragments of the human ribosomal RNA gene family from two types of tissue and three individuals were cloned in lambda vectors and compared by restriction enzyme digestion and electron microscopy. The EcoRI fragment A contains (i) 0.2 kb of the 3' end of the 18S rDNA, (ii) 2.5 kb of internal transcribed spacer and the 5.8S rDNA, and (iii) 4.6 kb of the 28S rDNA gene. All of the six cloned rDNA fragments isolated are identical by these analyses. Moreover, all contain a HincII site that is absent in about 50% of the rDNA identified by genomic blotting. Polymorphism in the nontranscribed spacer rDNA was studied in genomic blots of BamHI-digested DNA, using the 3' end of the 28S rDNA as a probe. The boundaries between the 18S rDNA, internal transcribed spacer, 28s rDNA, and external nontranscribed spacer were determined by R-loop analysis, further defining the organization of the ribosomal RNA precursor.

Bacteriophage lambda↗
PubMed1980

HeLa cell identification by analysis of ribosomal DNA segment patterns generated by endonuclease restriction.

Restriction endonuclease analysis of HeLa cells and cells in which origins have been questioned provides evidence in favor of a HeLa cell origin for the questioned cells. Digestion of cellular human DNA reveals a variable ribosomal DNA (rDNA) fragment that is present in up to four discrete sizes. Cell lines of known and suspected HeLa origin contain only two size variants. This pattern of variability serves to distinguish HeLa-derived cells from others. Despite repeated passage and divergence of the HeLa phenotype and karyotype, the restriction pattern is remarkably constant.

Base Sequence↗
PubMed1978

The association of chromosome 3 duplication and the Cornelia de Lange syndrome.

Two unrelated children with features of the Cornelia de Lange syndrome, including mental retardation, growth retardation, glaucoma, and a similar facies, had duplications corresponding to bands q25 leads to q29 of chromosome 3. These patients were compared to others with duplications of chromosome 3 and to a large series of patients with Cornelia de Lange syndrome. Diseases that sometimes involve characteristic chromosomal changes but have normal chromosomes in other instances are discussed.

Azure Stains↗
PubMed1978

Molecular analysis of cloned human 18S ribosomal DNA segments.

A fraction of DNA from the human fetal lung fibroblast line IMR-90, 30-fold enriched for ribosomal DNA, was cloned in the lambda phage vector Charon 16A. Of 978 clones assayed by hybridization to a mixture of 125I-labeled 18S and 28S ribosomal RNA, 11 recombinants containing a 3.8-megadalton segment of human 18S ribosomal DNA were identified. Restriction endonuclease analysis of these clones demonstrated variation only in orientation of the human gene segment within the phage vector. Restriction sites that we had previously detected from analysis of restriction products of unfractionated human DNA by using the Southern transfer method were also present in the cloned DNA segment. Recombinant DNA technology thus provides a valid and efficient means to define structural conservation or variation within families of human genes.

Cell Line↗
PubMed1976

Importance of full size complementary DNA in nucleic acid hybridization.

The size of the DNA product synthesized by RNA-directed DNA polymerase (isolated from avian myeloblastosis virus) was found to be important for complementary DNA (cDNA)-mRNA hybridization reactions. Incomplete cDNA to rabbit reticulocyte globin mRNA formed poor hybrids and presumably lacked sequences needed for hybridization. The size of the cDNA synthesized was influenced by the reaction conditions used. The complementary DNA product contained 10 S material when synthesis was done at high deoxynucleoside triphosphate concentrations (greater than 50 muM) while the product was smaller than the template when synthesis was at lower concentrations. The concentration and size (oligo(dT)6 to (dT)10) of primer had little or no effect on the product size. Increasing the concentration of 10 S globin mRNA caused the cDNA product to contain more small material. The cDNA synthesized at high deoxynucleoside triphosphate concentrations was fractionated into heavy, medium, and light fractions by alkaline sucrose density centrifugation. All hybridized to globin mRNA. The larger cDNAs had a higher TM when hybridized to globin mRNA, a lower dTMP/dCMP ratio (indicating that the poly(dT) region constituted a smaller fraction of the molecule), and gave increased protection of 125I-labeled mRNA from nuclease digestion. The full size cDNA was especially useful for studying the RNA transcribed from chromatin by RNA polymerase. The complement of the 5' end of the mRNA is contained only in full size cDNA; the 5' end is the part of the mRNA first transcribed by the RNA polymerase assuming correct transcription. Thus, full size cDNA can hybridize more effectively to the short RNA transcripts that are obtained than partial cDNA. RNA transcribed from rabbit bone marrow chromatin by Escherichia coli RNA polymerase hybridized twice as efficiently to complete cDNA as it did to partial cDNA demonstrating the usefulness of full size cDNA.

Animals↗
PubMed1975

Cell-free transcription of mammalian chromatin. Quantitative measurement of newly synthesized globin messenger RNA sequences.

Transcription of globin mRNA sequences from rabbit marrow chromatin was detected by hybridization with globin complementary DNA (cDNA). The presence of newly synthesized RNA in cDNA-globin mRNA hybrids isolated by Cs2SO4 density equilibrium centrifugation required the addition of both rabbit marrow chromatin and DNA-dependent RNA polymerase (Escherichia coli) to the transcription reaction. No globin mRNA sequences were detected in RNA transcribed from rabbit liver chromatin or from rabbit marrow DNA. Selective transcription of globin mRNA sequences was therefore tissue-specific and dependent on the presence of chromosomal proteins. Globin mRNA sequences synthesized by E. coli RNA polymerase were distinguished from those synthesized by chromatin-bound (endogenous) RNA polymerases by the use of alpha-amanitin. A typical reaction with rabbit marrow chromatin yielded 100 mug of purified RNA which contained approximately 5 ng (0.005%) of globin mRNA sequences synthesized by E. coli RNA polymerase, 1 ng (0.001%) of globin mRNA seqeences synthesized by endogenous RNA polymerases, and 4 ng (0.004%) of globin mRNA sequences derived from chromatin-associated (endogenous) RNA. Forty per cent of the globin mRNA sequences derived from endogenous RNA could be removed by poly(U)-Sepharose chromatography. The accurate measurement of globin mRNA sequences required improved conditions for the purification and hybridization of RNA transcribed from chromatin.

Animals↗
PubMed1975

Activation and inactivation of genes determining hemoglobin types.20s.

Globin gene switching in sheep and goats has been used as a model system for examining gene expression in differentiating red blood cells. Sheep and goats switch from the synthesis of hemoglobin A to hemoglobin C in response to erythropoietin. The regulatory mechanism producing this switch in hemoglobin types could occur at the cellular, nuclear, or cytoplasmic level. Evidence is presented which suggests that regulation is occurring, in fact, at the nuclear level. Sheep and goat erythroid colonies have been grown in plasma clot culture in order to study the synthesis of individual globin chains. Erythropoietin is required for colony formation. The switch from hemoglobin A to hemoglobin C synthesis requires not only colony formation but also a higher concentration of erythropoietin than is required just for the production of colonies. A cell-free transcriptional system using bone marrow chromatin and mammalian DNA-dependent RNA polymerase has been developed in order to examine the nuclear control mechanisms in more detail.

Amino Acid Sequence↗
PubMed1975

Strand-selective transcription of globin genes in rabbit erythroid cells and chromatin.

In order to investigate the symmetry of globin gene transcription, complementary RNA (cRNA) was synthesized using rabbit globin complementary DNA (cDNA) as a template for Escherichia coli DNA-dependent RNA polymerase (RNA nucleotidyltransferase). The cRNA hybridized specifically to its own cDNA template but not to sheep cDNA, rabbit globin mRNA, or poly(dT). Hybridization studies with cRNA demonstrated that RNA sequences transcribed from the DNA strand complementary to the globin gene region (anti-strand) were not present in cellular, total nuclear, or fractionated nuclear RNA from rabbit marrow. Such sequences were detected in RNA transcribed from rabbit marrow chromatin by E. coli or sheep liver RNA polymerases, but amounted to less than 50% of the globin mRNA sequences present in the same transcript. The evidence indicates that globin mRNA transcription is predominantly DNA strand specific.

Animals↗
PubMed1974

Cell-free transcription of mammalian chromatin: transcription of globin messenger RNA sequences from bone-marrow chromatin with mammalian RNA polymerase.

A mammalian cell-free transcriptional system was developed in which mammalian RNA polymerase synthesizes globin messenger RNA sequences from bone-marrow chromatin. The messenger RNA sequences are detected by measurement of the ability of the transcribed RNA to hybridize with globin complementary DNA. The globin complementary DNA is synthesized by the enzyme from avian myeloblastosis virus, RNA-directed DNA polymerase, with purified globin messenger RNA as template. The specificity of the globin complementary DNA in annealing reactions was verified by preparing DNA complementary to liver messenger RNA and showing that the globin and liver complementary DNAs are specific for their own messenger RNAs. Both DNA-dependent RNA polymerase II from sheep liver and RNA polymerase from Escherichia coli can transcribe globin messenger RNA sequences from rabbit bone-marrow chromatin; however, the mammalian enzyme appears to be more specific in that globin gene sequences represent a higher proportion of the RNA synthesized. Neither polymerase can transcribe globin messenger RNA sequences from rabbit-liver chromatin. This cell-free assay system should be useful in searching for mammalian transcriptional regulatory factors.

Animals↗
PubMedDate not supplied

Clasped-thumb mental retardation (MASA) syndrome: confirmation of linkage to Xq28.

We describe a 5-generation Hispanic family with 13 males and 1 female affected with MASA syndrome. The proposita, a 17-year-old female, and her affected male relatives shared many of the cognate manifestations--mental retardation (14/14), aphasia or delayed speech (13/13), shuffling gait (8/13), adduction of thumbs (14/14)--as well as scoliosis (2/13) and increased deep tendon reflexes in the lower extremities (10/13). Southern analysis with the polymorphic DNA probes DXS14 (Xp11), DXS72 (Xq21), and F8C (Xq28) confirmed linkage to the Xq28 region with a maximum lod score of 3.01 for this family.

Adolescent↗
PubMedDate not supplied

Duplication 8 [inv dup(8)(p12p23)] with macrocephaly.

A 10-month old female is described with inv dup(8)(p12p23) who had macrocephaly with subtle changes in facial appearance and no structural birth defects. Her findings, together with those of 37 reported cases with inv dup (8), define a syndrome that emphasizes the importance of genes on the 8p region for brain development.

Cerebral Ventricles↗