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"Frances, Lisa"
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Essex : the cultural impact of an Elizabethan courtier
\"This collection of new essays about the Earl of Essex, one of the most important figures of the Elizabethan court, resituates his life and career within the richly diverse contours of his cultural and political milieu. It identifies the ways in which his biography has been variously interpreted both during his own lifetime and since his death in 1601.\"--Page 4 of cover.
Book
Outdoor learning across the early years in Australia : Inconsistencies, challenges, and recommendations
In this article, we explore inconsistencies in the implementation of outdoor learning across Australian early years' education. The benefits of outdoor learning justify regular employment of this pedagogical approach in both early
childhood education and primary school settings. Early childhood education services provide daily outdoor learning opportunities as required by Australian national policy documents. However, Australian primary schools are not subject to
such requirements and teachers often face challenges regarding outdoor learning, thus regular implementation in primary classes can be a low priority. As children in the year before school and the first year of school have similar
learning and developmental needs, we argue that the benefits of outdoor learning should be available to all children across the early years. We also recommend regular outdoor learning in the first year of schooling to promote continuity
as children transition from early childhood education to primary schools. [Author abstract]
Journal Article
The NIN Transcription Factor Coordinates Diverse Nodulation Programs in Different Tissues of the Medicago truncatula Root
Biological nitrogen fixation in legumes occurs in nodules that are initiated in the root cortex following Nod factor recognition at the root surface, and this requires coordination of diverse developmental programs in these different tissues. We show that while early Nod factor signaling associated with calcium oscillations is limited to the root surface, the resultant activation of Nodule Inception (NIN) in the root epidermis is sufficient to promote cytokinin signaling and nodule organogenesis in the inner root cortex. NIN or a product of its action must be associated with the transmission of a signal between the root surface and the cortical cells where nodule organogenesis is initiated. NIN appears to have distinct functions in the root epidermis and the root cortex. In the epidermis, NIN restricts the extent of Early Nodulin 11 (ENOD11) expression and does so through competitive inhibition of ERF Required for Nodulation (ERN1). In contrast, NIN is sufficient to promote the expression of the cytokinin receptor Cytokinin Response 1 (CRE1), which is restricted to the root cortex. Our work in Medicago truncatula highlights the complexity of NIN action and places NIN as a central player in the coordination of the symbiotic developmental programs occurring in differing tissues of the root that combined are necessary for a nitrogen-fixing symbiosis.
Journal Article
Site and plant species are important determinants of the Methylobacterium community composition in the plant phyllosphere
The plant phyllosphere constitutes a habitat for numerous microorganisms; among them are members of the genus
Methylobacterium
. Owing to the ubiquitous occurrence of methylobacteria on plant leaves, they represent a suitable target for studying plant colonization patterns. The influence of the factor site, host plant species, time and the presence of other phyllosphere bacteria on
Methylobacterium
community composition and population size were evaluated in this study. Leaf samples were collected from
Arabidopsis thaliana
or
Medicago truncatula
plants and from the surrounding plant species at several sites. The abundance of cultivable
Methylobacterium
clearly correlated with the abundance of other phyllosphere bacteria, suggesting that methylobacteria constitute a considerable and rather stable fraction of the phyllosphere microbiota under varying environmental conditions. Automated ribosomal intergenic spacer analysis (ARISA) was applied to characterize the
Methylobacterium
community composition and showed the presence of similar communities on
A. thaliana
plants at most sites in 2 consecutive years of sampling. A substantial part of the observed variation in the community composition was explained by site and plant species, especially in the case of the plants collected at the
Arabidopsis
sites (50%). The dominating ARISA peaks that were detected on
A. thaliana
plants were found on other plant species grown at the same site, whereas some different peaks were detected on
A. thaliana
plants from other sites. This indicates that site-specific factors had a stronger impact on the
Methylobacterium
community composition than did plant-specific factors and that the
Methylobacterium
–plant association is not highly host plant species specific.
Journal Article
Competitiveness of Diverse Methylobacterium Strains in the Phyllosphere of Arabidopsis thaliana and Identification of Representative Models, Including M. extorquens PA1
Facultative methylotrophic bacteria of the genus Methylobacterium are consistently found in association with plants, particularly in the phyllosphere. To gain a better understanding of the mechanisms underlying the dispersal and occurrence of Methylobacterium on plants, diverse strains were isolated, identified, and studied with regard to their competitiveness on the model plant Arabidopsis thaliana. As a basis for this study a comprehensive collection of Methylobacterium isolates was established. Isolates were obtained from five different naturally grown A. thaliana populations and diverse other plant genera at these and further sites. They were classified using automated ribosomal internal spacer analysis (ARISA) and a representative subset was identified based on 16S rRNA gene sequence analysis. A comparison of their ARISA patterns with those generated based on a cultivation-independent approach from the same sampling material confirmed that the isolates were abundant colonizers of the studied plants. In competition experiments, colonization efficiency of the strains was found to be linked to phylogeny, rather than to the geographical origin or plant genus from which they were isolated. The most competitive colonizers were related to the species Methylobacterium tardum and Methylobacterium extorquens. Higher cell numbers were observed in the phyllosphere of A. thaliana when a mixture of different strains was applied relative to inoculation with only one strain, suggesting partial niche heterogeneity. Based on the results of the competition experiments, representative strains with different colonization efficiencies were selected, which will serve as models in future studies aiming at a better understanding of plant colonization by this bacterial genus. Among them is the meanwhile genome-sequenced strain M. extorquens PA1, which represents a competitive species of plant colonizers with a broad dispersal. This strain was characterized in more detail including physiological, morphological, and chemotaxonomical properties.
Journal Article
The Symbiosis-Related ERN Transcription Factors Act in Concert to Coordinate Rhizobial Host Root Infection
Legumes improve their mineral nutrition through nitrogen-fixing root nodule symbioses with soil rhizobia. Rhizobial infection of legumes is regulated by a number of transcription factors, including ERF Required for Nodulation1 (ERN1). Medicago truncatula plants defective in ERN1 are unable to nodulate, but still exhibit early symbiotic responses including rhizobial infection. ERN1 has a close homolog, ERN2, which shows partially overlapping expression patterns. Here we show that ern2 mutants exhibit a later nodulation phenotype than ern1, being able to form nodules but with signs of premature senescence. Molecular characterization of the ern2-1 mutation reveals a key role for a conserved threonine for both DNA binding and transcriptional activity. In contrast to either single mutant, the double ern1-1 ern2-1 line is completely unable to initiate infection or nodule development. The strong ern1-1 ern2-1 phenotype demonstrates functional redundancy between these two transcriptional regulators and reveals the essential role of ERN1/ERN2 to coordinately induce rhizobial infection and nodule organogenesis. While ERN1/ERN2 act in concert in the root epidermis, only ERN1 can efficiently allow the development of mature nodules in the cortex, probably through an independent pathway. Together, these findings reveal the key roles that ERN1/ERN2 play at the very earliest stages of root nodule development.
Journal Article
Plant-based foods in Canada: information, trust and closing the commercialization gap
Purpose
Despite the growing awareness of links between meat consumption and human, animal and environmental health, consumption rates of protein rich plant-based foods (PBFs) in Canada remain relatively low. The purpose of this paper is to better understand how information sources and trust relate to PBFs in Canadians’ diets, and how these variables may factor into closing the commercialization gap for PBFs in Canada.
Design/methodology/approach
A geographically representative sample of Canadians (n=410) participated in a 20-minute, online survey. The survey consists of 24 questions covering demographic characteristics, motivations behind current and future food choices, frequency of current PBF consumption, sources of information about PBFs and trust levels of these sources.
Findings
Most Canadians get information about PBFs from labels, the internet and family and friends, but only half trust these sources to provide accurate information. Sources of information (e.g. licensed health care professionals) that rank high in trust are only consulted by a minority of respondents. Several information sources (e.g. family and friends) are associated with consumers’ willingness to try new PBFs, whereas other sources (e.g. labels) are associated with Canadians being unlikely to try new PBFs.
Originality/value
Understanding the patterns of where Canadians access information about PBFs and what sources of information are trusted can help to strategically place information about PBF qualities among select information sources and to remove some of the information barriers contributing to the PBF commercialization gap.
Journal Article
A Phylogenetically Conserved Group of Nuclear Factor-Y Transcription Factors Interact to Control Nodulation in Legumes
The endosymbiotic association between legumes and soil bacteria called rhizobia leads to the formation of a new root-derived organ called the nodule in which differentiated bacteria convert atmospheric nitrogen into a form that can be assimilated by the host plant. Successful root infection by rhizobia and nodule organogenesis require the activation of symbiotic genes that are controlled by a set of transcription factors (TFs). We recently identifiedMedicago truncatulanuclear factor-YA1 (MtNF-YA1) and MtNF-YA2 as twoM. truncatulaTFs playing a central role during key steps of theSinorhizobium meliloti-M. truncatulasymbiotic interaction. NF-YA TFs interact with NF-YB and NF-YC subunits to regulate target genes containing the CCAAT box consensus sequence. In this study, using a yeast two-hybrid screen approach, we identified the NF-YB and NF-YC subunits able to interact with MtNF-YA1 and MtNF-YA2. In yeast (Saccharomyces cerevisiae) and in planta, we further demonstrated by both coimmunoprecipitation and bimolecular fluorescence complementation that these NF-YA, -B, and -C subunits interact and form a stable NF-Y heterotrimeric complex. Reverse genetic and chromatin immunoprecipitation-PCR approaches revealed the importance of these newly identified NF-YB and NF-YC subunits for rhizobial symbiosis and binding to the promoter ofMtERN1(for Ethylene Responsive factor required for Nodulation), a direct target gene of MtNF-YA1 and MtNF-YA2. Finally, we verified that a similar trimer is formed in planta by the common bean (Phaseolus vulgaris) NF-Y subunits, revealing the existence of evolutionary conserved NF-Y protein complexes to control nodulation in leguminous plants. This sheds light on the process whereby an ancient heterotrimeric TF mainly controlling cell division in animals has acquired specialized functions in plants.
Journal Article
Epistatic Interactions between Opaque2 Transcriptional Activator and Its Target Gene CyPPDK1 Control Kernel Trait Variation in Maize
Association genetics is a powerful method to track gene polymorphisms responsible for phenotypic variation, since it takes advantage of existing collections and historical recombination to study the correlation between large genetic diversity and phenotypic variation. We used a collection of 375 maize (Zea mays ssp. mays) inbred lines representative of tropical, American, and European diversity, previously characterized for genome-wide neutral markers and population structure, to investigate the roles of two functionally related candidate genes, Opaque2 and CyPPDK1, on kernel quality traits. Opaque2 encodes a basic leucine zipper transcriptional activator specifically expressed during endosperm development that controls the transcription of many target genes, including CyPPDK1, which encodes a cytosolic pyruvate orthophosphate dikinase. Using statistical models that correct for population structure and individual kinship, Opaque2 polymorphism was found to be strongly associated with variation of the essential amino acid lysine. This effect could be due to the direct role of Opaque2 on either zein transcription, zeins being major storage proteins devoid of lysine, or lysine degradation through the activation of lysine ketoglutarate reductase. Moreover, we found that a polymorphism in the Opaque2 coding sequence and several polymorphisms in the CyPPDK1 promoter nonadditively interact to modify both lysine content and the protein-versus-starch balance, thus revealing the role in quantitative variation in plants of epistatic interactions between a transcriptional activator and one of its target genes.
Journal Article