| 1. |
- Dryselius, Rikard, et al.
(författare)
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Variable coordination of cotranscribed genes in Escherichia coli following antisense repression
- 2006
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Ingår i: BMC Microbiology. - : Springer Science and Business Media LLC. - 1471-2180. ; 6, s. 97-
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Tidskriftsartikel (refereegranskat)abstract
- Background: A majority of bacterial genes belong to tight clusters and operons, which complicates gene functional studies using conventional knock-out methods. Antisense agents can down-regulate the expression of genes without disrupting the genome because they bind mRNA and block its expression. However, it is unclear how antisense inhibition affects expression from genes that are cotranscribed with the target. Results: To examine the effects of antisense inhibition on cotranscribed genes, we constructed a plasmid expressing the two reporter genes gfp and DsRed as one transcriptional unit. Incubation with antisense peptide nucleic acid (PNA) targeted to the mRNA start codon region of either the upstream gfp or the downstream DsRed gene resulted in a complete expression discoordination from this artificial construct. The same approach was applied to the three cotranscribed genes in the endogenously expressed lac-operon (lacZ, Y and A) and partial downstream expression coordination was seen when the lacZ start codon was targeted with antisense PNA. Targeting the lacY mRNA start codon region showed no effect on the upstream lacZ gene expression whereas expression from the downstream lacA gene was affected as strongly as the lacY gene. Determination of lacZ and lacY mRNA levels revealed a pattern of reduction that was similar to the Lac-proteins, indicating a relation between translation inhibition and mRNA degradation as a response to antisense PNA treatment. Conclusion: The results show that antisense mediated repression of genes within operons affect cotranscribed genes to a variable degree. Target transcript stability appears to be closely related to inhibition of translation and presumably depends on translating ribosomes protecting the mRNA from intrinsic decay mechanisms. Therefore, for genes within operons and clusters it is likely that the nature of the target transcript will determine the inhibitory effects on cotranscribed genes. Consequently, no simple and specific methods for expression control of a single gene within polycistronic operons are available, and a thorough understanding of mRNA regulation and stability is required to understand the results from both knock-down and knock-out methods used in bacteria.
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| 2. |
- Gustafsson, Britt, et al.
(författare)
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KI, WU, and Merkel Cell Polyomavirus DNA was not Detected in Guthrie Cards of Children who Later Developed Acute Lymphoblastic Leukemia
- 2012
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Ingår i: Journal of pediatric hematology/oncology (Print). - 1077-4114 .- 1536-3678. ; 34:5, s. 364-367
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Tidskriftsartikel (refereegranskat)abstract
- Background: Neonatal dried blood spots (Guthrie cards) have been used to demonstrate a prenatal origin of clonal leukemia-specific genetic aberrations in several subgroups of childhood acute lymphoblastic leukemia (ALL). One hypothesis suggests that an infectious agent could initiate genetic transformation already in utero. In search for a possible viral agent, Guthrie cards were analyzed for the presence of 3 newly discovered polyomavirus Karolinska Institutet polymavirus (KIPyV), Washington University polyomavirus (WUPyV), and Merkel cell polyomavirus (MCPyV). Methods: Guthrie cards from 50 children who later developed ALL and 100 matched controls were collected and analyzed by standard or real-time polymerase chain reaction for the presence of the VP1 region of KIPyV, WUPyV, and MCPyV, and the LT region for MCPyV. Results and Conclusions: DNA from KIPyV, WUPyV, and MCPyV was not detected in neonatal blood samples from children with ALL or controls. Prenatal infections with these viruses are not likely to be etiological drivers for childhood leukemogenesis.
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| 3. |
- Nikravesh, Abbas, et al.
(författare)
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Antisense PNA Accumulates in Escheria coli and mediates a Long Post-antibiotic Effect
- 2008
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Ingår i: Molecular Therapy. - : Elsevier BV. - 1525-0016 .- 1525-0024. ; 15:8, s. 1537-1542
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Tidskriftsartikel (refereegranskat)abstract
- Antisense agents that target growth-essential genes display surprisingly potent bactericidal properties. In particular, peptide nucleic acid (PNA) and phosphorodiamidate morpholino oligomers linked to cationic carrier peptides are effective in time kill assays and as inhibitors of bacterial peritonitis in mice. It is unclear how these relatively large antimicrobials overcome stringent bacterial barriers and mediate killing. Here we determined the transit kinetics of peptide–PNAs and observed an accumulation of cell-associated PNA in Escherichia coli and slow efflux. An inhibitor of drug efflux pumps did not alter peptide–PNA potency, indicating a lack of active efflux from cells. Consistent with cell retention, the post-antibiotic effect (PAE) of the anti-acyl carrier protein (acpP) peptide–PNA was greater than 11 hours. Bacterial cell accumulation and a long PAE are properties of significant interest for antimicrobial development.
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| 4. |
- Sullivan, Patrick F, et al.
(författare)
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An unbiased metagenomic search for infectious agents using monozygotic twins discordantfor chronic fatigue
- 2011
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Ingår i: BMC Microbiology. - : BMC. - 1471-2180. ; 11:2
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Tidskriftsartikel (refereegranskat)abstract
- Background: Chronic fatigue syndrome is an idiopathic syndrome widely suspected of having an infectious orimmune etiology. We applied an unbiased metagenomic approach to try to identify known or novel infectiousagents in the serum of 45 cases with chronic fatigue syndrome or idiopathic chronic fatigue. Controls were theunaffected monozygotic co-twins of cases, and serum samples were obtained at the same place and time.Results: No novel DNA or RNA viral signatures were confidently identified. Four affected twins and no unaffectedtwins evidenced viremia with GB virus C (8.9% vs. 0%, p = 0.019), and one affected twin had previously undetectedhepatitis C viremia. An excess of GB virus C viremia in cases with chronic fatigue requires confirmation.Conclusions: Current, impairing chronic fatigue was not robustly associated with viremia detectable in serum.
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| 5. |
- Aad, G, et al.
(författare)
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- 2015
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