Unknown,Transcriptomics,Genomics,Proteomics

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Heritability of the expression of defense-related genes in the outer stem of Interior spruce (Picea glauca x engelmannii)

ABSTRACT: Inferring the heritability of gene expression is one of the main areas of the field of genetical genomics. With the possibility to treat the abundances of gene transcripts as a suite of quantitative traits, genetical genomics can make an extensive use of the microarray technology. Here we extended a major method for estimating the heritability of a quantitative trait, single parent-offspring regression, to assess the heritability of the expression of genes with two-channel microarrays. In a series of maternal parent-offspring pairs of Interior spruce (Picea glauca x engelmannii, our focus in the outer stem tissues is the expression of defense-related genes, the heritability of which can affect fitness and necessary for evolution by natural selection. Parent-offspring pairs of Interior spruce planted as a part of Tree Breeding and Improvement Program of the Forest Genetics Section, British Columbia Ministry of Forests and Range, Prince George, BC, Canada (http://www.for.gov.bc.ca/hre/forgen/interior/spruce.htm#1) were used. A total of 30 trees, comprising 15 parent-offpsring pairs were sampled. These include15 offsprings and 15 maternal parents (grafts), which were planted within ~ 1Km range west (122º 42’ 43’’W, 53º 45’41’’N) of the offsprings, hence grown in a relatively similar environment. The bark and the attached phloem were separated from inner layers in the mid-morning hours of June 25, 2008, flash-frozen in liquid nitrogen, and transferred into separate containers. A chain design was decided for gene expression profiling (a total of 45 slides) using the Treenomix third generation cDNA microarray platform (GEO accession #: GPL5423). Array350 kit (Genisphere, Hatfield, USA) was chosen for the microarray hybridizations. The slides were scanned with a ProScanArray scanner (PerkinElmer, Downers Grove, IL, USA), and the scanned TIF images were processed by ImaGene software (BioDiscovery, Inc., El Segundo, CA, USA) to quantify spot signals. Normalization was done between arrays using variance stabilizing (VSN) method for ratio based analysis of the expression data.

ORGANISM(S): Picea engelmannii x Picea glauca

SUBMITTER: Dr. Kermit Ritland

PROVIDER: E-GEOD-22921 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The objective of this study was to investigate which genes are important for Streptococcus pyogenes during intracellular survival in human macrophages. Streptococcus pyogenes is an important human pathogen, which has recently gained recognition as an intracellular microorganism during the course of severe invasive infections such as necrotizing fasciitis. Although the surface anchored M protein has been identified as a pivotal factor affecting phagosomal maturation and S. pyogenes survival within macrophages, the overall transcriptional profile required for the pathogen to adapt and persist intracellularly is yet unknown. To address this, gene expression profiles of S. pyogenes within human macrophages were determined and compared to those of extracellular bacteria using customized microarrays and real-time qRT-PCR. In order to model the early phase of infection involving adaptation to the intracellular compartment, samples were collected 2h post-infection and within 2 h post infection, the expression of 145 streptococcal genes was significantly altered in the intracellular environment. The majority of differentially regulated genes were associated with metabolic and energy-dependent processes. Key upregulated genes in early phase intracellular bacteria were ihk and irr, encoding a two-component gene regulatory system (TCS). We observed that an isogenic S. pyogenes mutant deficient in ihk/irr displayed significantly reduced bacterial counts as compared to wild-type bacteria following infection of macrophages. Comparison of gene expression of selected genes at 2h and 6h post-infection revealed a dramatic shift in response regulators over time with a down-regulation of ihk/irr genes concurrent with an upreguation of the well-studied covR/S two component regulator. In reinfection assays, intracellular bacteria from the 6h time point exhibited significantly greater survival within macrophages than did bacteria collected at the 2h time point. The findings illustrate how gene expression of S. pyogenes during the intracellular life cycle is fine-tuned by temporal expression of specific two-component systems. Five samples with three biological replicates are analysed. Each open reading frame in triplicate (three technical replicas per sample). Resulting in 6-9 data points per gene per condition. The extracellular bacteria are control samples and the internal control is the house-keeping gene gyrase.

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Heritability of the expression of defense-related genes in the outer stem of Interior spruce (Picea glauca x engelmannii)

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