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Biomedical subjects

I C Hoskins

Publications and source records attributed to I C Hoskins.

5 recordsLinked to original sources
PubMed1997

Identification of restriction barriers in Pasteurella multocida.

Several naturally occurring antibiotic resistance plasmids were isolated from Pasteurella multocida type D strains. One plasmid, pPM1, was used to study transfer of DNA among P. multocida strains, and could be transferred into Escherichia coli and some P. multocida isolates. However, pPM1 could only be transferred into the toxigenic P. multocida LFB3 at very low frequency. Plasmid recovered from the electrotransformants could be transferred to LFB3 at high frequency. These plasmid DNAs were resistant to PstI, and sensitive to DpnI digestion. Sensitivity to DpnI was common to all the P. multocida DNAs, but resistance to PstI was confined to LFB3. Plasmid pPM1 treated with PstI methylase was able to transform LFB3 at an increased frequency compared to unmethylated DNA, suggesting that LFB3 has a restriction system which cleaves at or near PstI sites.

DNA, Bacterial↗
PubMed1996

Constitutive expression of Pasteurella multocida toxin.

The expression of the Pasteurella multocida toxin (PMT) gene toxA was investigated. Growth in vitro at 30 degrees C or added iron caused less than 4-fold repression of toxA expression. The putative repressor TxaR was expressed in Escherichia coli but deletion and frameshift mutations abolishing TxaR production had no effect on toxA expression. Naturally occurring non-toxigenic mutants which contained the toxA gene had no large rearrangements near toxA or changes in toxA promoter structure. Thus PMT is constitutively expressed and is only regulated in a minor way.

Bacterial Proteins↗
PubMed1994

Expression of the 3-phosphoglycerate kinase gene (pgkA) of Penicillium chrysogenum.

The sequence of the Penicillium chrysogenum pgkA gene promoter was determined up to 952 nucleotides (nt) 5' to the major transcriptional start point (position +1), and contains a 38 bp pyrimidine-rich region within which transcription initiates at this and two minor sites (-11, -23). A 21 bp segment (-99 to -79) closely matches a region which is essential for the expression of the Aspergillus nidulans pgkA gene. A further region was found with similarity to sequences in other A. nidulans promoters possibly effecting response to carbon source. The terminator region of the P. chrysogenum pgkA gene was sequenced as far as 192 nt 3' to the stop codon and three polyadenylation sites were found at 94, 103 and 107 nt from this point, the first preceded by a possible polyadenylation signal. No transcription termination signal was found but several regions potentially forming stem-loop-structures were noted. A single 1.3 kb pgkA mRNA was readily detected by Northern blot analysis of total cellular RNA. Steady-state levels of pgkA mRNA were 1.5 to 2.0 times greater in mycelium harvested at similar stages of growth from medium containing the carbon sources acetate or quinate compared to glucose. A transformed strain of P. chrysogenum containing a fusion of the pgkA promoter to the Escherichia coli lacZ reporter gene integrated at the oliC locus was constructed, and beta-galactosidase activity monitored during growth of batch cultures in defined media. The pgkA promoter activity increased during exponential growth and was 2-3 times greater and increased most rapidly in mycelium grown on quinate or acetate compared to glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗