Unknown,Transcriptomics,Genomics,Proteomics

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Open Ocean and Coastal Strains of Marine Synechococcus display distinctly different Global Responses to DNA Damaging Agents

ABSTRACT: We have looked at the transcriptional response of well characterised Synechococcus open ocean (WH8102) and coastal (CC9311) isolates to two DNA damaging agents, mitomycin C and ethidium bromide, using whole genome expression microarrays. The coastal strain, which was able to grow on higher concentrations of both chemicals, showed differential regulation of a larger proportion of its genome following M-bM-^@M-^Xtoxic shockM-bM-^@M-^Y treatment with each agent. Many of the orthologous genes in these strains, including those encoding sensor kinases, showed different transcriptional responses, with the CC9311 genes more likely to show significant changes for each tested treatment. While the overall response of each strain was considerably different, there were distinct transcriptional responses common to both strains observed for each DNA damaging agent, linked to the mode of action of each chemical. In both CC9311 and WH8102 there was evidence of SOS response induction under mitomycin C treatment, with genes encoding recA, the lexA repressor and umuC significantly upregulated in this experiment but not under ethidium bromide treatment. Conversely, ethidium bromide treatment tended to result in upregulation of the DNA-directed RNA polymerase genes, not observed following mitomycin C treatment. Interestingly, a large number of genes residing on putative genomic island regions of each genome also showed significant upregulation under one or both chemical treatments. In this series four conditions have been analyzed. These are 2 hour incubations (shock treatment) with ethidium bromide (EB, final conc 2ug/mL) and mitomycin C (MC, final conc 0.5 ug/mL) for Synechococcus sp. WH8102 and CC9311. For each slide, an experimental RNA sample was labeled with Cy3 or Cy5 and was hybridized with a reference RNA from a control sample (no addition of chemical agent) labeled with the other Cy dye. There are six slides per condition, each with at least two biological replicates and three technical replicates, including at least one flip-dye comparison. Each slide contains six replicate spots per gene.

ORGANISM(S): Synechococcus sp. WH 8102

SUBMITTER: Sasha Tetu

PROVIDER: E-GEOD-39818 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Cyanobacteria are highly abundant in the oceans where they are constantly exposed to lytic viruses. Some viruses are restricted to a narrow host range while others infect a broad range of hosts. It is currently unknown whether broad-host range phages employ the same infection program, or regulate their program in a host-specific manner to accommodate for the different genetic makeup and defense systems of each host. Here we used a combination of microarray and RNA-seq analyses to investigate the interaction of three phylogentically distinct Synechococcus strains, WH7803, WH8102, and WH8109, with the broad-host range T4-like myovirus, Syn9, during infection. Strikingly, we found that the phage led a nearly identical expression program in the three hosts despite considerable differences in host gene content. On the other hand, host responses to infection involved mainly host-specific genes, suggesting variable attempts at defense against infection. A large number of responsive host genes were located in hypervariable genomic islands, substantiating genomic islands as a major axis of phage-bacteria interactions in cyanobacteria. Furthermore, transcriptome analyses and experimental determination of the complete phage promoter map revealed three temporally regulated modules and not two as previously thought for cyanophages. In contrast to T4, an extensive, previously unknown regulatory motif drives expression of early genes and host-like promoters drive middle-gene expression. These promoters are highly conserved among cyanophages and host-like middle promoters extend to other T4-like phages, indicating that the well-known mode of regulation in T4 is not the rule among the broad family of T4-like phages. We investigated the infection process and transcriptional program of the P-TIM40 cyanophage during infection of a Prochlorococcus NATL2A host. The results are discussed in conjunction with results obtained from the infection process for the Syn9 cyanophage in three different Synechococcus hosts: WH7803 (Dufresne et al. 2008), WH8102 (Palenik et al. 2003) and WH8109 (sequenced as part of this study).

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Open Ocean and Coastal Strains of Marine Synechococcus display distinctly different Global Responses to DNA Damaging Agents

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