Writing Practice: Invention And Pedagogy In Composition

My dissertation re-engages a central question of composition and rhetoric – can writing be taught? – as a means of interrogating the relationship between form and response. In so doing, I argue that writing can be trained as a set of capacities and dispositions through repeated practice with rhetorical forms. In advancing this claim, I demonstrate that formal practices, such as modal writing, imitation, and repetition, have been unfairly dismissed as overly rote and mechanical because form has traditionally been understood as a technical means of achieving a particular end. I argue that, instead, repeated engagement with and movement between forms cultivates a rhetorical agility that allows writers to more inventively and ethically respond to the uniqueness of particular writing situations. Beyond the classroom, I argue that the pedagogical power of iterative engagements with form helps shape one’s ability to respond to difference more generally. Along these lines, my argument interrogates the pedagogical consequences of practicing writing program administration and theorizes a means by which to cultivate a rhetorical agility within an institutional context. Thus, I ultimately claim that writing cannot be taught as generalizable products and processes, but can be cultivated at un/conscious, bodily, and affective levels that enable writers and administrators to respond inventively to the singular demands of the rhetorical situations they encounter. This means that, far from functioning as technical skills, writing and rhetoric are enmeshed in a rhetor’s habitual capacity to respond to difference

A systems biology model of the regulatory network in Populus leaves reveals interacting regulators and conserved regulation

<p>Abstract</p> <p>Background</p> <p>Green plant leaves have always fascinated biologists as hosts for photosynthesis and providers of basic energy to many food webs. Today, comprehensive databases of gene expression data enable us to apply increasingly more advanced computational methods for reverse-engineering the regulatory network of leaves, and to begin to understand the gene interactions underlying complex emergent properties related to stress-response and development. These new systems biology methods are now also being applied to organisms such as <it>Populus</it>, a woody perennial tree, in order to understand the specific characteristics of these species.</p> <p>Results</p> <p>We present a systems biology model of the regulatory network of <it>Populus </it>leaves. The network is reverse-engineered from promoter information and expression profiles of leaf-specific genes measured over a large set of conditions related to stress and developmental. The network model incorporates interactions between regulators, such as synergistic and competitive relationships, by evaluating increasingly more complex regulatory mechanisms, and is therefore able to identify new regulators of leaf development not found by traditional genomics methods based on pair-wise expression similarity. The approach is shown to explain available gene function information and to provide robust prediction of expression levels in new data. We also use the predictive capability of the model to identify condition-specific regulation as well as conserved regulation between <it>Populus </it>and <it>Arabidopsis</it>.</p> <p>Conclusions</p> <p>We outline a computationally inferred model of the regulatory network of <it>Populus </it>leaves, and show how treating genes as interacting, rather than individual, entities identifies new regulators compared to traditional genomics analysis. Although systems biology models should be used with care considering the complexity of regulatory programs and the limitations of current genomics data, methods describing interactions can provide hypotheses about the underlying cause of emergent properties and are needed if we are to identify target genes other than those constituting the "low hanging fruit" of genomic analysis.</p

A cross-species transcriptomics approach to identify genes involved in leaf development

<p>Abstract</p> <p>Background</p> <p>We have made use of publicly available gene expression data to identify transcription factors and transcriptional modules (regulons) associated with leaf development in <it>Populus</it>. Different tissue types were compared to identify genes informative in the discrimination of leaf and non-leaf tissues. Transcriptional modules within this set of genes were identified in a much wider set of microarray data collected from leaves in a number of developmental, biotic, abiotic and transgenic experiments.</p> <p>Results</p> <p>Transcription factors that were over represented in leaf EST libraries and that were useful for discriminating leaves from other tissues were identified, revealing that the C2C2-YABBY, CCAAT-HAP3 and 5, MYB, and ZF-HD families are particularly important in leaves. The expression of transcriptional modules and transcription factors was examined across a number of experiments to select those that were particularly active during the early stages of leaf development. Two transcription factors were found to collocate to previously published Quantitative Trait Loci (QTL) for leaf length. We also found that miRNA family 396 may be important in the control of leaf development, with three members of the family collocating with clusters of leaf development QTL.</p> <p>Conclusion</p> <p>This work provides a set of candidate genes involved in the control and processes of leaf development. This resource can be used for a wide variety of purposes such as informing the selection of candidate genes for association mapping or for the selection of targets for reverse genetics studies to further understanding of the genetic control of leaf size and shape.</p

Norway spruce deploys tissue-specific responses during acclimation to cold

Climate change in the conifer-dominated boreal forest is expected to lead to warmer but more dynamic winter air temperatures, reducing the depth and duration of snow cover and lowering winter soil temperatures. To gain insight into the mechanisms that have enabled conifers to dominate extreme cold environments, we performed genome-wide RNA-Seq analysis from needles and roots of non-dormant two-year Norway spruce (Picea abies (L.) H. Karst), and contrasted these response to herbaceous model Arabidopsis We show that the main transcriptional response of Norway spruce needles exposed to cold was delayed relative to Arabidopsis, and this delay was associated with slower development of freezing tolerance. Despite this difference in timing, Norway spruce principally utilizes early response transcription factors (TFs) belonging to the same gene families as Arabidopsis, indicating broad evolutionary conservation of cold response networks. In keeping with their different metabolic and developmental states, needles and root of Norway spruce showed contrasting results. Regulatory network analysis identified both conserved TFs with known roles in cold acclimation (e.g. homologs of ICE1, AKS3, and of the NAC and AP2/ERF superfamilies), but also a root-specific bHLH101 homolog, providing functional insights into cold stress response strategies in Norway spruce

BatchMap: A parallel implementation of the OneMap R package for fast computation of F-1 linkage maps in outcrossing species

With the rapid advancement of high throughput sequencing, large numbers of genetic markers can be readily and cheaply acquired, but most current software packages for genetic map construction cannot handle such dense input. Modern computer architectures and server farms represent untapped resources that can be used to enable higher marker densities to be processed in tractable time. Here we present a pipeline using a modified version of OneMap that parallelizes over bottleneck functions and achieves substantial speedups for producing a high density linkage map (N = 20,000). Using simulated data we show that the outcome is as accurate as the traditional pipeline. We further demonstrate that there is a direct relationship between the number of markers used and the level of deviation between true and estimated order, which in turn impacts the final size of a genetic map

Genome-wide profiling of Populus small RNAs

<p>Abstract</p> <p>Background</p> <p>Short RNAs, and in particular microRNAs, are important regulators of gene expression both within defined regulatory pathways and at the epigenetic scale. We investigated the short RNA (sRNA) population (18-24 nt) of the transcriptome of green leaves from the sequenced <it>Populus trichocarpa </it>using a concatenation strategy in combination with 454 sequencing.</p> <p>Results</p> <p>The most abundant size class of sRNAs were 24 nt. Long Terminal Repeats were particularly associated with 24 nt sRNAs. Additionally, some repetitive elements were associated with 22 nt sRNAs. We identified an sRNA hot-spot on chromosome 19, overlapping a region containing both the proposed sex-determining locus and a major cluster of <it>NBS-LRR </it>genes. A number of phased siRNA loci were identified, a subset of which are predicted to target PPR and <it>NBS-LRR </it>disease resistance genes, classes of genes that have been significantly expanded in <it>Populus</it>. Additional loci enriched for sRNA production were identified and characterised. We identified 15 novel predicted microRNAs (miRNAs), including miRNA*sequences, and identified a novel locus that may encode a dual miRNA or a miRNA and short interfering RNAs (siRNAs).</p> <p>Conclusions</p> <p>The short RNA population of <it>P. trichocarpa </it>is at least as complex as that of <it>Arabidopsis thaliana</it>. We provide a first genome-wide view of short RNA production for <it>P. trichocarpa </it>and identify new, non-conserved miRNAs.</p

Comparative Fungal Community Analyses Using Metatranscriptomics and Internal Transcribed Spacer Amplicon Sequencing from Norway Spruce

The health, growth, and fitness of boreal forest trees are impacted and improved by their associated microbiomes. Microbial gene expression and functional activity can be assayed with RNA sequencing (RNA-Seq) data from host samples. In contrast, phylogenetic marker gene amplicon sequencing data are used to assess taxonomic composition and community structure of the microbiome. Few studies have considered how much of this structural and taxonomic information is included in transcriptomic data from matched samples. Here, we described fungal communities using both host-derived RNA-Seq and fungal ITS1 DNA amplicon sequencing to compare the outcomes between the methods. We used a panel of root and needle samples from the coniferous tree species Picea abies (Norway spruce) growing in untreated (nutrient-deficient) and nutrient-enriched plots at the Flakaliden forest research site in boreal northern Sweden. We show that the relationship between samples and alpha and beta diversity indicated by the fungal transcriptome is in agreement with that generated by the ITS data, while also identifying a lack of taxonomic overlap due to limitations imposed by current database coverage. Furthermore, we demonstrate how metatranscriptomics data additionally provide biologically informative functional insights. At the community level, there were changes in starch and sucrose metabolism, biosynthesis of amino acids, and pentose and glucuronate interconversions, while processing of organic macromolecules, including aromatic and heterocyclic compounds, was enriched in transcripts assigned to the genus Cortinarius.IMPORTANCE A deeper understanding of microbial communities associated with plants is revealing their importance for plant health and productivity. RNA extracted from plant field samples represents the host and other organisms present. Typically, gene expression studies focus on the plant component or, in a limited number of studies, expression in one or more associated organisms. However, metatranscriptomic data are rarely used for taxonomic profiling, which is currently performed using amplicon approaches. We created an assembly-based, reproducible, and hardware-agnostic workflow to taxonomically and functionally annotate fungal RNA-Seq data obtained from Norway spruce roots, which we compared to matching ITS amplicon sequencing data. While we identified some limitations and caveats, we show that functional, taxonomic, and compositional insights can all be obtained from RNA-Seq data. These findings highlight the potential of metatranscriptomics to advance our understanding of interaction, response, and effect between host plants and their associated microbial communities

Ray Parenchymal Cells Contribute to Lignification of Tracheids in Developing Xylem of Norway Spruce

A comparative transcriptomic study and a single-cell metabolome analysis were combined to determine whether parenchymal ray cells contribute to the biosynthesis of monolignols in the lignifying xylem of Norway spruce (Picea abies). Ray parenchymal cells may function in the lignification of upright tracheids by supplying monolignols. To test this hypothesis, parenchymal ray cells and upright tracheids were dissected with laser-capture microdissection from tangential cryosections of developing xylem of spruce trees. The transcriptome analysis revealed that among the genes involved in processes typical for vascular tissues, genes encoding cell wall biogenesis-related enzymes were highly expressed in both developing tracheids and ray cells. Interestingly, most of the shikimate and monolignol biosynthesis pathway-related genes were equally expressed in both cell types. Nonetheless, 1,073 differentially expressed genes were detected between developing ray cells and tracheids, among which a set of genes expressed only in ray cells was identified. In situ single cell metabolomics of semi-intact plants by picoliter pressure probe-electrospray ionization-mass spectrometry detected monolignols and their glycoconjugates in both cell types, indicating that the biosynthetic route for monolignols is active in both upright tracheids and parenchymal ray cells. The data strongly support the hypothesis that in developing xylem, ray cells produce monolignols that contribute to lignification of tracheid cell walls. Transcriptomics combined with single-cell metabolomics give new information on the role of rays in lignification of developing xylem in Norway spruce.Peer reviewe

PAP and NT5E inhibit nociceptive neurotransmission by rapidly hydrolyzing nucleotides to adenosine

Peer reviewe

Cone-setting in spruce is regulated by conserved elements of the age-dependent flowering pathway

Reproductive phase change is well characterized in angiosperm model species, but less studied in gymnosperms. We utilize the early cone-setting acrocona mutant to study reproductive phase change in the conifer Picea abies (Norway spruce), a gymnosperm. The acrocona mutant frequently initiates cone-like structures, called transition shoots, in positions where wild-type P. abies always produces vegetative shoots. We collect acrocona and wild-type samples, and RNA-sequence their messenger RNA (mRNA) and microRNA (miRNA) fractions. We establish gene expression patterns and then use allele-specific transcript assembly to identify mutations in acrocona. We genotype a segregating population of inbred acrocona trees. A member of the SQUAMOSA BINDING PROTEIN-LIKE (SPL) gene family, PaSPL1, is active in reproductive meristems, whereas two putative negative regulators of PaSPL1, miRNA156 and the conifer specific miRNA529, are upregulated in vegetative and transition shoot meristems. We identify a mutation in a putative miRNA156/529 binding site of the acrocona PaSPL1 allele and show that the mutation renders the acrocona allele tolerant to these miRNAs. We show co-segregation between the early cone-setting phenotype and trees homozygous for the acrocona mutation. In conclusion, we demonstrate evolutionary conservation of the age-dependent flowering pathway and involvement of this pathway in regulating reproductive phase change in the conifer P. abies