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"Parrott, David"
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The business of war : military enterprise and military revolution in early modern Europe
\"This is a major new approach to the military revolution and the relationship between warfare and the power of the state in early modern Europe. Whereas previous accounts have emphasised the growth of state-run armies during this period, David Parrott argues instead that the delegation of military responsibility to sophisticated and extensive networks of private enterprise reached unprecedented levels. This included not only the hiring of troops but their equipping, the supply of food and munitions, and the financing of their operations. The book reveals the extraordinary prevalence and capability of private networks of commanders, suppliers, merchants and financiers who managed the conduct of war on land and at sea, challenging the traditional assumption that reliance on mercenaries and the private sector results in corrupt and inefficient military force. In so doing, the book provides essential historical context to contemporary debates about the role of the private sector in warfare\"-- Provided by publisher.
BOOK
Epistatic and allelic interactions control expression of ribosomal RNA gene clusters in Arabidopsis thaliana
Background
Ribosomal RNA (rRNA) accounts for the majority of the RNA in eukaryotic cells, and is encoded by hundreds to thousands of nearly identical gene copies, only a subset of which are active at any given time. In
Arabidopsis thaliana
, 45S rRNA genes are found in two large ribosomal DNA (rDNA) clusters and little is known about the contribution of each to the overall transcription pattern in the species.
Results
By taking advantage of genome sequencing data from the 1001 Genomes Consortium, we characterize rRNA gene sequence variation within and among accessions. Notably, variation is not restricted to the pre-rRNA sequences removed during processing, but it is also present within the highly conserved ribosomal subunits. Through linkage mapping we assign these variants to a particular rDNA cluster unambiguously and use them as reporters of rDNA cluster-specific expression. We demonstrate that rDNA cluster-usage varies greatly among accessions and that rDNA cluster-specific expression and silencing is controlled via genetic interactions between entire rDNA cluster haplotypes (alleles).
Conclusions
We show that rRNA gene cluster expression is controlled via complex epistatic and allelic interactions between rDNA haplotypes that apparently regulate the entire rRNA gene cluster. Furthermore, the sequence polymorphism we discovered implies that the pool of rRNA in a cell may be heterogeneous, which could have functional consequences.
Journal Article
Silvae
\"Statius' Silvae, thirty-two occasional poems, were written probably between 89 and 96 AD. Here the poet congratulates friends, consoles mourners, offers thanks, admires a monument or artistic object, and describes a memorable scene. The verse is light in touch, with a distinct pictorial quality. Statius gives us in these impromptu poems clear images of Domitian's Rome. Statius was raised in the Greek cultural milieu of the Bay of Naples, and his Greek literary education lends a sophisticated veneer to his ornamental verse. The role of the emperor and the imperial circle in determining taste is also readily apparent: the figure of the emperor Domitian permeates these poems.\"-- Publisher description.
Book
Designing Skid-Trail Networks to Reduce Skidding Cost and Soil Disturbance for Ground-Based Timber Harvesting Operations
Skid-trail locations directly influence the economics and environmental impacts of harvesting operations. Typically, field managers design skid-trail networks manually based on field observations of vegetation and terrain conditions. We designed a model to automatically design skid-trail networks to reduce skidding costs and soil disturbances. The model simulates tree-bunch locations, creates a feasible skid-trail network across the harvest unit, estimates skidding cost and soil recovery cost for each feasible skid-trail segment, and finds the network design that connects each tree bunch to landings while reducing skidding and soil recovery costs. The model was applied to a 24-ha hypothetical harvest unit to test its ability to design optimal networks under different scenarios representing conditions commonly found in timber harvesting operations (e.g., skidding pattern, uneven volume distribution, skidding obstacles, and different weights given to skidding and soil recovery costs). It was also applied to an actual 124-ha harvest unit to evaluate its ability to design skid-trail networks considering more realistic conditions with multiple design factors. The model successfully created optimized skid-trail networks for all scenarios considered, and results suggest that it provides a useful tool to help forest engineers and field managers design economically efficient and environmentally sound ground-based timber harvesting operations.
Journal Article
Analysis of barley (Hordeum vulgare) leaf senescence and protease gene expression: a family C1A cysteine protease is specifically induced under conditions characterized by high carbohydrate, but low to moderate nitrogen levels
Senescence is the highly regulated last developmental phase of plant organs and tissues, and is optimized to allow nutrient remobilization to surviving plant parts, such as seeds of annual crops. High leaf carbohydrate to nitrogen (C : N) ratios have been implicated in the induction or acceleration of the senescence process. A combination of phloem interruption in mature leaves (by steam-girdling, leading to carbohydrate accumulation from photosynthesis) and varied nitrate supply was used to analyse correlations between metabolite levels, leaf senescence parameters and induction of protease genes and proteolytic activities. Its strong induction under conditions characterized by high C : N ratios, negative correlation of its transcript levels with chlorophylls and nitrates, its strong induction during developmental leaf senescence and its predicted localization to a lytic vacuolar compartment indicate that, among the genes tested, a family C1A cysteine protease is most likely to participate in bulk protein degradation during barley leaf senescence. While all the genes analysed were selected based on upregulation during leaf senescence in a previous transcriptomic study, a considerably more detailed picture of protease gene regulation emerged from the data presented here, underlining the usefulness of this experimental approach for further (functional) protease characterization.
Journal Article
The Mobile bypass Signal Arrests Shoot Growth by Disrupting Shoot Apical Meristem Maintenance, Cytokinin Signaling, and WUS Transcription Factor Expression
The bypass1 (bps1) mutant of Arabidopsis (Arabidopsis thaliana) produces a root-sourced compound (the bps signal) that moves to the shoot and is sufficient to arrest growth of a wild-type shoot; however, the mechanism of growth arrest is not understood. Here, we show that the earliest shoot defect arises during germination and is a failure of bps1 mutants to maintain their shoot apical meristem (SAM). This finding suggested that the bps signal might affect expression or function of SAM regulatory genes, and we found WUSCHEL (WUS) expression to be repressed in bps1 mutants. Repression appears to arise from the mobile bps signal, as the bps1 root was sufficient to rapidly down-regulate WUS expression in wild-type shoots. Normally, WUS is regulated by a balance between positive regulation by cytokinin (CK) and negative regulation by CLAVATA (CLV). In bps1, repression of WUS was independent of CLV, and, instead, the bps signal down-regulates CK responses. Cytokinin treatment of bps1 mutants restored both WUS expression and activity, but only in the rib meristem. How the bps signal down-regulates CK remains unknown, though the bps signal was sufficient to repress expression of one CK receptor (AHK4) and one response regulator (AHP6). Together, these data suggest that the bps signal pathway has the potential for long-distance regulation through modification of CK signaling and altering gene expression.
Journal Article
Steam-Girdling of Barley (Hordeum vulgare) Leaves Leads to Carbohydrate Accumulation and Accelerated Leaf Senescence, Facilitating Transcriptomic Analysis of Senescence-Associated Genes
• Leaf senescence can be described as the dismantling of cellular components during a specific time interval before cell death. This has the effect of remobilizing N in the form of amino acids that can be relocalized to developing seeds. High levels of carbohydrates have previously been shown to promote the onset of the senescence process. • Carbohydrate accumulation in barley (Hordeum vulgare) plants was induced experimentally by steam-girdling at the leaf base, occluding the phloem, and gene regulation under these conditions was investigated using the Affymetrix Barley GeneChip array and quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR). • Transcript levels of plastidial (aminopeptidases, cnd41) and vacuolar (thiol and serine) proteases clearly increase in girdled leaves. Of special interest are cnd41, a plastidial aspartyl peptidase that has been implicated in Rubisco degradation in tobacco; and cp-mlll, a highly upregulated carboxypeptidase. SAG12, hexokinases and other senescence-specific genes are also upregulated under these conditions. • Applying a genomic approach to the innovative experimental system described here significantly enhances our knowledge of leaf proteolysis and whole-plant N recycling.
Journal Article
Control of barley (Hordeum vulgareL.) development and senescence by the interaction between a chromosome six grain protein content locus, day length, and vernalization
Regulatory processes controlling traits such as anthesis timing and whole-plant senescence are of primary importance for reproductive success and for crop quality and yield. It has previously been demonstrated that the presence of alleles associated with high grain protein content (GPC) at a locus on barley chromosome six leads to accelerated leaf senescence, and to strong (>10-fold) up-regulation of several genes which may be involved in senescence control. One of these genes (coding for a glycine-rich RNA-binding protein termedHvGR-RBP1) exhibits a high degree of similarity toArabidopsisglycine-rich RNA-binding protein 7 (AtGRP7), which has been demonstrated to accelerate flowering under both long-day (LD) and short-day (SD) conditions, but not after vernalization. Development of near-isogenic barley lines, differing in the allelic state of the GPC locus, was compared from the seedling stage to maturity under both SD and LD and after vernalization under LD. Intriguingly, pre-anthesis plant development [measured by leaf emergence timing and pre-anthesis (sequential) leaf senescence] was enhanced in high-GPC germplasm. Differences were more pronounced under SD than under LD, but were eliminated by vernalization, associating observed effects with floral induction pathways. By contrast, differences in post-anthesis flag leaf and whole-plant senescence between low- and high-GPC germplasm persisted under all tested conditions, indicating that the GPC locus, possibly throughHvGR-RBP1, impacts on both developmental stages. Detailed molecular characterization of this experimental system may allow the dissection of cross-talk between signalling pathways controlling early plant and floral development on one side, and leaf/whole-plant senescence on the other side.
Journal Article
Comparative transcriptome profiling of near-isogenic barley (Hordeum vulgare) lines differing in the allelic state of a major grain protein content locus identifies genes with possible roles in leaf senescence and nitrogen reallocation
To identify genes involved in the regulation and execution of leaf senescence and whole-plant nitrogen reallocation, near-isogenic barley germplasm divergent in senescence timing and protein concentration of mature grains was contrasted. Barley lines differing in allelic state at a major locus on chromosome six, controlling grain protein concentration, were obtained after four generations of backcrossing. Based on physiological data indicating major differences between low- and high-grain protein germplasm at 14-21 d past anthesis, the flag leaf and kernel transcriptomes of the low-protein parent and one high-protein near-isogenic line were compared at these time points, using the 22-k Barley1 Affymetrix microarray. Our data associate several genes with both known (based on sequence comparisons) and unknown functions with the senescence process. These include leucine-rich repeat transmembrane protein kinases, a glycine-rich RNA-binding protein with homology to AtGRP7 and a 'mother of FT/TF1' gene. Our data also indicate upregulation of genes coding for both plastidial and extraplastidial proteases in germplasm with accelerated leaf senescence. Functional characterization of candidate genes identified by this research may contribute to our understanding of the molecular network underlying leaf senescence and nitrogen reallocation.
Journal Article
A Dendroecological Investigation of an Upland Oak-Dominated Forest within the Grand Prairie Region of Illinois
We studied an upland forest located within the Grand Prairie region of Illinois and utilized tree-ring analysis to document tree cohort development and radial growth in relation to stand disturbance and climate. The overstory within the Humiston Woods Nature Center (Livingston County, Illinois) study area was dominated by oak (Quercus spp.), hickory (Carya spp.), and ash (Fraxinus spp.), while the subordinate crown classes were principally composed of elm (Ulmus spp.) and sugar maple (Acer saccharum). The study area contained tree cohorts originating during two recruitment periods. Overstory oaks and hickories primarily established between 1865 and 1900. A second tree cohort was associated with a timber harvest occurring in the late 1960s. In contrast to the 1865–1900 recruitment period, trees within the 1965–1980 cohort were primarily ash, elm, sugar maple, and black cherry (Prunus serotina). RWI values were most strongly correlated with Palmer Drought Severity Index, precipitation, and temperature in June of the current growth year. RWI and radial increment data for overstory oaks highlighted a sustained growth increase following a late 1960s timber harvest that remained high relative to predisturbance growth rates even in pronounced drought years. Data provide needed insight into oak woodland recruitment patterns relating to disturbance regimes that are difficult to recreate at the landscape level but often serve as ecological restoration objectives. Our findings help extend the foundational knowledge regarding forest composition, stand level dynamics, and radial growth relationships present among upland forests and changing disturbance patterns in the Grand Prairie region of Illinois.
Journal Article