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Biomedical subjects

G G Wilson

Publications and source records attributed to G G Wilson.

At least 55 records · Page 3Linked to original sources
PubMed1987

Cloning, sequencing and expression of the Taq I restriction-modification system.

The Taq I modification and restriction genes (recognition sequence TCGA) have been cloned in E. coli and their DNA sequences have been determined. Both proteins were characterized and the N-terminal sequence of the endonuclease was determined. The genes have the same transcriptional orientation with the methylase gene 5' to the endonuclease gene. The methylase gene is 1089 bp in length (363 amino acids, 40,576 daltons); the endonuclease gene is 702 bp in length (234 amino acids, 27,523 daltons); they are separated by 132 bp. Both methylase and endonuclease activity can be detected in cell extracts. The clones fully modify the vector and chromosomal DNA but they fail to restrict infecting phage. Clones carrying only the restriction gene are viable even in the absence of modification. The restriction gene contains 7 Taq I sites; the modification gene contains none. This asymmetric distribution of sites could be important in the regulation of the expression of the endonuclease gene.

Amino Acid Sequence↗
PubMed1987

Cloning, sequencing, in vivo promoter mapping, and expression in Escherichia coli of the gene for the HhaI methyltransferase.

A 1476-base pair DNA fragment from Haemophilus haemolyticus containing the HhaI methyltransferase gene was isolated from a cell library and cloned into pBR322. The nucleotide sequence of this fragment was determined. The structural gene is 981 nucleotides in length coding for a protein of 327 amino acids (Mr 37,000). The translational start signal (ATG) is preceded by the putative ribosome-binding site (TAAG). Recombinant plasmids containing the 1476-basepair fragment are completely methylated when isolated from Escherichia coli, as judged by their insusceptibility to the HhaI restriction endonuclease. However, the presence of an active HhaI methylase gene in certain E. coli strains results in a very poor yield of transformants and/or in vivo-originated deletions due to the Rg1 functions of these hosts. The in vivo transcription initiation sites have been identified by S1 protection and primer-extension experiments using specific probes with total RNA prepared from E. coli cells (HB101 or RR1) which tolerate the expression of MHhaI.

Amino Acid Sequence↗
PubMed1987

N4-methylcytosine as a minor base in bacterial DNA.

The DNA base composition, including the minor base content, of 26 strains of bacteria was determined. The studied bacteria are sources of widely used restriction endonucleases. Approximately 35% of the bacterial DNAs contained N4-methylcytosine, about 60% contained 5-methylcytosine, and about 90% had N6-methyladenine.

Bacteria↗
PubMed1982

Genetic analysis of bacteriophage T4 transducing bacteriophages.

Mutations in the genes for nuclear disruption (ndd), endonuclease IV (denB), and the D1 region of the T4 genome are essential for converting bacteriophage T4 into a generalized transducing phage. These mutations gave rise to a very low frequency of transduction, about 10(-8) per infected bacterium. The addition of an rII mutation raised the transduction frequency about 20-fold. An additional 100-fold increase in the transduction frequency was observed with mutations in genes 42, 56, and alc. High-frequency generalized transduction by T4 results from the cumulative effect of these mutations.

Chromosome Deletion↗
PubMed1982

Traumatic perineal laceration.

Four cases of pelvic trauma associated with a deep perineal tear are reported. The mechanism of injury, preoperative and operative care of this type of injury are discussed. The theory that the tear is similar to an explosion is presented. Categories of anorectal injury are listed. As expected, genitourinary and rectal injuries as well as hemorrhage are the primary concerns with this type of trauma. Management consists of careful evaluation for genitourinary tract injury followed by careful inspection of the perineal tear in the operating room. Rectal examination is crucial and proctosigmoidoscopy is advised for all injuries. Sepsis is the most important complication of the perineal tear. Prevention begins with mandatory colostomy for all patients. The loop colostomy serves as the necessary totally diverting colostomy. Equally important is evacuation and washout of distal fecal content of colon during operation. Hemorrhage may assume greater importance than with closed injuries due to the loss of tamponade. Hypogastric ligation at the time of exploration and colostomy may be beneficial. Drainage of the pararectal space is necessary when the rectum is directly involved in the tear.

Adult↗
PubMed1979

Tracheoesophageal space abscess.

Two cases of a newly described complication of endotracheal intubation are presented with a discussion of the pathophysiology, clinical symptoms, and treatment evaluation. Treated late, bilateral arytenoid fixation associated with subglottic stenosis is the eventual outcome. Reconstructive efforts in one patient have allowed decannulation two years after onset of his disease following bilateral arytenoidectomy. No reconstructive efforts were attempted in the second patient because of her basic underlying disease process. Early recognition is important and exploratory laryngotracheal-fissure advocated for suspected cases in order to perhaps decrease the devastating consequences of late treatment.

Abscess↗
PubMed1977

Molecular cloning of fragments of bacteriophage T4 DNA.

Non-glucosylated T4 DNA was digested with R.EcoRI and the resulting fragments covalently joined to lambda vectors. The genetic content of each lambda-T4 hybrid was determined by marker-rescue tests. The isolation of many recombinants containing partial-digestion products of T4 DNA provided the overlapping sequences necessary to order fragments within the T4 genome. The present analyses include parts of the "early" region between genes 42 and 46, and much of the "late" region between genes 50 and 29. T4 cytosine-DNA digested to completion by R.EcoRI was used to identify the fragments of DNA within the lambda-T4 recombinants. The T4 cytosine-DNA was also sensitive to R.HindIII and R.Xho but not to R.BamH1.

Chromosome Mapping↗
PubMedDate not supplied

Sequence comparison of the EcoHK31I and EaeI restriction-modification systems suggests an intergenic transfer of genetic material.

The genes coding for the EcoHK31I and EaeI restriction-modification (R-M) systems from Escherichia coli strain HK31 and Enterobacter aerogenes, respectively, have been cloned and sequenced. Both ENases recognize and cleave Y/GGCCR leaving 4 nucleotide 5'-protruding ends, while the MTases modify the internal cytosine. The systems were isolated on a 2.3kb AseI fragment for EcoHK31I, and a 4.6 kb HindIII fragment for EaeI. The R and M genes of both systems converge and overlap by 14 nucleotides. Previously, we found that M.EcoHK31I consisted of two subunits, (alpha and beta), with the beta subunit being translated from an alternative open reading frame within the gene encoding the alpha subunit. Sequence comparison between the EcoHK31I and EaeI systems reveals striking similarity. The eaeIM gene also encodes alpha and beta polypeptides of 309 and 176 amino acids which share 96% and 97% identity, respectively, with those of ecoHK31IM. ecoHK31IR and eaeIR encode proteins of 318 and 315 aa, respectively, which share 92% identity but are otherwise unique in the GenBank database. The EaeI and the EcoHK31I R-M systems were found to be flanked by genes coding for integrases. It is possible that these integrases have facilitated the transfer of this system among different bacterial species.

Amino Acid Sequence↗