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Biomedical subjects

S Surrey

Publications and source records attributed to S Surrey.

122 records · Page 7Linked to original sources
PubMed1979

The 5' terminal capping of heterogeneous nuclear RNA at different embryonic stages of the sea urchin.

5' Terminal cap structures of hnRNA have been characterized and the extent of capping determined as a function of embryonic development. Sea urchin embryo hnRNA contains only the type-1 cap, m7GpppNmpNp, with the type-2 cap, which has a 2'-0-methylated subpenultimate nucleotide, being associated only with stable small nuclear RNAs. These cap 2-containing RNAs are synthesized at a rate of approximately 70 molecules min-1 nucleus-1 compared to approximately 1000 molecules for hnRNA cap 1. Approximately 70% of nuclear cap 1 is associated with greater than 15S RNA in denaturing solvent, but under non-denaturing conditions the percentage is much higher. Cap 1 in low and high molecular weight nuclear RNA have the same kinetics of methyl labeling. Thus all cap 1 structures may belong to a single class either covalent or H-bonded to high molecular weight RNA. hnRNA greater than 15S is 35% capped; however, adding caps in less than 15S RNA gives an estimate of 50% capping for total hnRNA. In development from early blastula to late gastrula, there is little if any change in the extent of capping of hnRNA. These results coupled with others indicate that the fraction of hnRNA molecules serving as precursor to mRNA does not change quantitatively during embryonic development.

Animals↗
PubMed1976

Methylated blocked 5' terminal sequences of sea urchin embryo messenger RNA classes containing and lacking poly(A).

Sea urchin embryo mRNAs of three distinct classes--histone mRNA, nonhistone mRNA containing poly(A), "[+A] mRNA," and nonhistone mRNA lacking poly(A), "[-A]mRNA"--all contain blocked 5' terminal sequences in which 7-methylguanosine is linked 5'-5' via a triphosphate bridge to a 2'-0-methylated nucleotide. Only one general type of 5' terminal structure, 7mGpppXmpYp, is present. Additional 2'-0-methylation in the Y residue has not been found either in early or late stage embryos. A substantial proportion of the polyribosomal mRNAs in all three classes contain this blocked structure. Whereas both classes of nonhistone mRNAs have internal base methylations, histone mRNAs lack such modifications.

Adenosine↗
PubMed1975

Nuclear deoxyribonucleic acid polymerases of liver.

Hepatic nuclei that are isolated in aquenous solutions of low ionic strength or glycerol contain all or nearly all the nonmitochondrial DNA polymerase activity of the cell. The presence of polymerase activity in the cytoplasm is due to extraction of nuclear enzymes by buffer and inorganic salts. Even with low ionic strength solutions, some leaching of nuclear enzymes occurs if the concentration of liver in the homogenizing medium is greater than 10%. As defined by sucrose gradient analysis, the normal adult rat liver nucleus contains mainly or entirely a single species of DNA polymerase (3.2 S) whereas the regenerating nucleus after 70% hepatectomy has an additional enzyme (7.1 S). The total activity of regenerating nuclei is about twice the normal value. The increase resides in the 7.1 S activity. The 7.1 S DNA polymerase had been purified partially from regenerating liver nuclei (isolated in low ionic strength solutions) and cytosol (prepared under conditions of nuclear enzyme extraction). The properties of the activity from the two sources are indistinguishable. A mixture of albumin and spermidine enhances by several-fold the activities of the 3.2 S and 7.1 S DNA polymerases. In the presence of spermidine, but not in its absence, the activity of the 7.1 S DNA polymerase is strictly proportional to the amount of the enzyme preparation.

Animals↗
PubMedDate not supplied

Parallel molecular genetic analysis.

We describe recent progress in parallel molecular genetic analyses using DNA microarrays, gel-based systems, and capillary electrophoresis and utilization of these approaches in a variety of molecular biology assays. These applications include use of polymorphic markers for mapping of genes and disease-associated loci and carrier detection for genetic diseases. Application of these technologies in molecular diagnostics as well as fluorescent technologies in DNA analysis using immobilized oligonucleotide arrays on silicon or glass microchips are discussed. The array-based assays include sequencing by hybridization, cDNA expression profiling, comparative genome hybridization and genetic linkage analysis. Developments in non microarray-based, parallel analyses of mutations and gene expression profiles are reviewed. The promise of and recent progress in capillary array electrophoresis for parallel DNA sequence analysis and genotyping is summarized. Finally, a framework for decision making in selecting available technology options for specific molecular genetic analyses is presented.

DNA↗
PubMedDate not supplied

Linkage of DFNB1 to non-syndromic neurosensory autosomal-recessive deafness in Mediterranean families.

Recent studies show a susceptibility locus (DFNB1) responsible for non-syndromic neurosensory autosomal-recessive deafness (NSRD) mapping to the pericentromeric region of chromosome 13q. In order to better understand the frequency with which DFNB1 is the gene for deafness in our patient population and the role of DFNB1 in Caucasians, we performed a genetic linkage study with four microsatellite markers linked to DFNB1 in a total of 48 independent Mediterranean families, of which 30 and 18 were of Italian and Spanish descent, respectively. A maximum two-point lod score of 7.28 was found with marker D13S115 at a recombination frequency of theta 0.1. Significant lod scores were also obtained for D13S143, D13S292 and D13S175. Genetic heterogeneity was confirmed using the HOMOG program which indicated absence of linkage to DFNB1 in approximately 21% of the sample. This study clearly demonstrates that DFNB1 plays an important role in 79% of Mediterranean families with NSRD. Furthermore, results from multipoint analysis predict that the DFNB1 gene maps between markers D13S175 and D13S115 which are separated by approximately 14.2 cM.

Chromosome Mapping↗