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Biomedical subjects

G B Petersen

Publications and source records attributed to G B Petersen.

At least 37 records · Page 2Linked to original sources
PubMed1992

Ring chromosome 22 and neurofibromatosis.

Variable constitutional mosaicism, mos45,XY,-22/46,XY,-22,+mar/46,XY,-22,+r(22)/47,XY,-22,+r(22)+mar/ 47, XY,-22,+r(22)*2, was found in PHA-stimulated peripheral blood, in a lymphoblastoid cell line and in cultured skin fibroblasts from a mentally retarded patient with neurofibromatosis. Both the ring chromosome and the small extra marker chromosome stained positively by in situ hybridization with a chromosome 14/22-specific alphoid repeat probe. DNA dosage analysis showed constitutional loss of one copy of the arylsulfatase A gene (ARSA), consistent with its terminal location on 22q. There was no evidence of constitutional loss of D22S1 or D22S28 which flank the neurofibromatosis type 2 (NF2) locus. Analysis of two DNA samples from a skin neurofibroma indicated retainment of two copies of D22S1, whereas the results were ambiguous with respect to tumor-specific loss of one copy of D22S28. It is suggested that the development of neurofibromatosis of unclear type in two r(22) carriers might be associated with somatic mutation of the NF2 locus due to instability of the ring chromosome(s), and in analogy, that somatic mutation of either NF1 or NF2 may account for some cases of neurofibromatosis which do not meet the criteria of either NF1 or NF2. The occurrence of seminoma in the proband may be fortuitous, but could also be due to the presence of a seminoma-associated locus on chromosome 22.

Adult↗
PubMed1992

Ovine follistatin: characterization of cDNA and expression in sheep ovary during the luteal phase of the oestrous cycle.

We have isolated ovine follistatin cDNA from an ovarian follicle cDNA library and determined its sequence. The deduced amino acid sequence of the ovine follistatin precursor is highly homologous (greater than 97%) to the porcine, human and rat follistatins. Northern analysis was used to characterize follistatin gene expression in ovaries of adult ewes, collected from days 11 to 13 of the oestrous cycle. Two major (about 2.7 kb and 1.5 kb) and one minor (about 0.5 kb) transcripts were detected in polyadenylated RNA extracted from ovarian follicles and corpora lutea. The degree of expression of the transcripts varied in the two ovarian compartments, with the 2.7 kb species predominating in the follicles and the 1.5 kb species being more abundant in the corpora lutea. No transcripts were detected in stromal tissue containing preantral follicles of less than 1 mm.

Amino Acid Sequence↗
PubMed1991

The putative single-stranded DNA-binding protein of the filamentous bacteriophage, Ifl. Amino acid sequence of the protein and structure of the gene.

The protein product corresponding to the gene located in the region of the coliphage Ifl genome shown to contain the code for the single-stranded DNA (ssDNA)-binding proteins of all filamentous phages so far studied has been isolated from infected bacterial cells and its amino acid sequence determined. The mature protein contains 95 amino acids (calculated molecular mass 10553 Da). Its sequence corresponds to that predicted from the DNA sequence but lacks the initiating methionine residue. Although there is little direct sequence homology between the phage Ifl protein and the ssDNA-binding proteins of the other filamentous phages that have been studied, computer-based comparisons of various physical and structural parameters showed that the phage Ifl protein contains a domain that is closely related to domains in the coliphage T4 gene 32 protein and the Pseudomonas phage Pfl ssDNA-binding protein and suggest that the Ifl protein does have a ssDNA-binding function although we were unable to show this directly.

Amino Acid Sequence↗
PubMed1991

DNA sequence of the filamentous bacteriophage Pf1.

The genome of the class II filamentous bacteriophage Pf1 has been sequenced by a combination of the chain termination and chemical degradation methods. It consists of 7349 nucleotides in a closed, circular loop of single-stranded DNA. The size and position of its open reading frames (ORFs) in general resemble those of other filamentous bacteriophage genomes. The size and position of the spaces between the ORFs have not been conserved, however, and six short reading frames (2 of which overlap) occupy a region corresponding to that filled by genes 2 and 10 in the Ff genome. Most of the ORFs are preceded by sequences resembling ribosome binding sites from the phage's host. Pseudomonas aeruginosa, that appear to differ somewhat from their counterparts in Escherichia coli. A search for sequences related to known pseudomonad promoters suggests that the promoters in this bacteriophage may well be ntr-dependent, with the two strongest preceding the gene for the major coat protein (gene 8) and another ORF (430). Gene 8 is followed by a sequence with the properties of a rho-independent terminator of transcription, like that at the same position in the genome of Ff. The Pf1 genome contains no collection of potential stem-and-loop structures corresponding to those that initiate replication of Ff DNA and assembly of the Ff virion, although isolated structures of this kind are present. The available evidence suggests that at least 13 of the 14 major ORFs are expressed. Overall, the organization of the Pf1 genome differs from that of the other class II filamentous phage whose genome has been sequenced, Pf3, as much as it does from that of the class I phages Ff and IKe.

Amino Acid Sequence↗
PubMed1990

A case of 46,XX,r(X) (p1q1) diagnosed by in situ hybridization.

A small marker chromosome was identified as an X-derived ring chromosome by in situ hybridization with a biotinylated X-chromosome specific a-satellite DNA probe. This procedure clearly determined the chromosomal origin of the marker chromosome, which had been impossible to define by conventional cytogenetic techniques including high resolution banding.

Centromere↗
PubMed1988

Messenger RNA recognition in Escherichia coli: a possible second site of interaction with 16S ribosomal RNA.

Examination of the nucleotides following the ATG or GTG initiation codons of a file of 251 genes from Escherichia coli has shown that 247 (98.4%) of them contain a sequence of at least three and 168 (66.9%) of them a sequence of at least four consecutive nucleotides that is complementary to some part of the 16 nt at the 5' terminus of the bacterial 16S rRNA. It is proposed that this sequence, which falls within the first 24 nt coding for the genetic message, might be involved in mRNA recognition through a mechanism analogous to the well-established 'Shine--Dalgarno' interaction with the 3' terminus of the 16S rRNA. Comparison of these data with data derived from a file of 117 'false' gene starts that have a Shine--Dalgarno-like sequence followed by a suitably spaced ATG or GTG triplet but which are believed not to lie at the beginnings of genetic messages shows the association that we have found to be statistically significant at the 99.9% level.

Escherichia coli↗
PubMed1987

HOMED: a homologous sequence editor.

The alignment of homologous sequences with each other and their display has proved a difficult task, despite a frequent requirement for this process. HOMED enables related sequences to be edited and listed in parallel with each other. The editor function uses a full screen editor which emulates the text editors KED and EDT (on PDP-11 and VAX-11 respectively) and which can be adapted to emulate other text editors. This emulation has been adopted to simplify user learning of editing functions. HOMED provides functions for listing the sequences in a variety of formats and for generating a consensus sequence as well as providing a series of tools for maintenance of the sequence database. HOMED has been implemented in Pascal in a modular fashion to enhance portability.

Algorithms↗
PubMed1986

Ribulose 1,5-bisphosphate carboxylase. Effect on the catalytic properties of changing methionine-330 to leucine in the Rhodospirillum rubrum enzyme.

Oligonucleotide-directed mutagenesis of cloned Rhodospirillum rubrum ribulose bisphosphate carboxylase/oxygenase with a synthetic 13mer oligonucleotide primer was used to effect a change at Met-330 to Leu-330. The resultant enzyme was kinetically examined in some detail and the following changes were found. The Km(CO2) increased from 0.16 to 2.35 mM, the Km(ribulose bisphosphate) increased from 0.05 to 1.40 mM for the carboxylase reaction and by a similar amount for the oxygenase reaction. The Ki(O2) increased from 0.17 to 6.00 mM, but the ratio of carboxylase activity to oxygenase activity was scarcely affected by the change in amino acid. The binding of the transition state analogue 2-carboxyribitol 1,5-bisphosphate was reversible in the mutant and essentially irreversible in the wild type enzyme. Inhibition by fructose bisphosphate, competitive with ribulose bisphosphate, was slightly increased in the mutant enzyme. These data suggest that the change of the residue from methionine to leucine decreases the stability of the enediol reaction intermediate.

Base Sequence↗
PubMed1984

The DNA of bacteriophage 643: isolation and properties of the DNA of a bacteriophage infecting lactic Streptococci.

The DNA extracted from bacteriophage 643, which infects group N strains of Streptococci, could be separated into four components by electrophoresis on agarose gels. Electron microscopy established the predominant form of the DNA to be a relaxed, circular molecule of molecular weight 14.9 X 10(6). The four species observed on electrophoresis are believed to be a circular monomeric form, a linear form derived from it, a circular dimeric form, and the corresponding linear dimer. Two DNA components were demonstrated by sedimentation velocity in the analytical ultracentrifuge and by zone sedimentation in sucrose gradients. These corresponded to a circular monomeric form and a circular dimeric form; no evidence for supercoiled forms was found by sedimentation in either neutral or denaturing solvents. Bacteriophage 643 DNA was sensitive to cleavage by single-strand-specific nuclease S1 and could be labeled in vitro by the PolI-catalyzed incorporation of [alpha-32P]dATP into the molecule under conditions that did not permit nick translation, suggesting that the circular duplex molecule is interrupted by a single-stranded gap.

Bacteriophages↗
PubMed1984

Method for Growth and Purification of Bacteriophage 643 on Streptococcus lactis ML3.

The yield of bacteriophage 643 was increased by infecting cultures of Streptococcus lactis ML3 in late-log phase growth, harvesting the infected cells, and suspending them in fresh, phosphate-buffered minimal medium. The cells lysed after this treatment and produced high titers of bacteriophage. The phage particles were dissociated from debris by 2 M NaCl and purified by differential and CsCl band centrifugation.

Journal Article↗
PubMed1983

Linkage and chromosome study of multiple endocrine neoplasia IIa.

A linkage and chromosome investigation of a large family with multiple endocrine neoplasia (MEN) IIa (medullary thyroid carcinoma, pheochromocytoma, and occasionally hyperparathyroidism) was undertaken. No significantly positive lodscores were obtained between MEN IIa and 25 different genetic markers. Conventional metaphase chromosome analysis showed normal karyotypes and no heterochromatin markers linked to the MEN IIa locus were found. High-resolution chromosome analysis in five MEN IIa carriers revealed no deletion within band 20p12.2. The present investigation could thus neither demonstrate linkage of the MEN IIa locus to genetic or chromosome markers nor identify chromosome abnormalities in MEN IIa carriers.

Adolescent↗
PubMed1982

The DNA-binding protein of Pf1 filamentous bacteriophage: amino-acid sequence and structure of the gene.

The amino-acid sequence of the single-stranded DNA-binding protein of bacteriophage Pf1 and the nucleotide sequence of the corresponding gene have been determined. The protein has 144 amino acids and a molecular weight of 15 400; the gene consists of 435 nucleotides. The amino-acid sequence was determined by Edman degradation, carboxypeptidase A, B, and P digestion of intact protein and of peptides derived by chymotrypsin, Staphylococcus aureus V8 protease, and trypsin digestion. The nucleotide sequence was determined by the dideoxy method after random cloning of fragments of Pf1 DNA into M13. No sequence homology could be established between the amino-acid sequence of the DNA-binding protein of Pseudomonas aeruginosa-specific bacteriophage Pf1 and bacteriophage fd of Escherichia coli.

Journal Article↗