The Lantern Vol. 68, No. 2, Spring 2001

• Eden • Ginsberg Mourning • On the Cusp of Winter • (Woman: as Needing to be Silver and Sharp) • Descended • Book Unbinding • Scrawlings on the Stall • My Frankenstein • Jazzy Avantguardia • Paper Crane • A Child\u27s Valentine • Ten Years\u27 Gone • Out the Window • Tar\u27s Melting • Passing Time • Ave Maria • Heart of the Matter • Damn Kids • The Candle Incident • Nostalgia • Cuban Couch • Dinner Datehttps://digitalcommons.ursinus.edu/lantern/1158/thumbnail.jp

Singularity resolution depends on the clock

We study the quantum cosmology of a flat Friedmann–Lemaître–Robertson–Walker Universe filled with a (free) massless scalar field and a perfect fluid that represents radiation or a cosmological constant whose value is not fixed by the action, as in unimodular gravity. We study two versions of the quantum theory: the first is based on a time coordinate conjugate to the radiation/dark energy matter component, i.e., conformal time (for radiation) or unimodular time. As shown by Gryb and Thébault, this quantum theory achieves a type of singularity resolution; we illustrate this and other properties of this theory. The theory is then contrasted with a second type of quantisation in which the logarithm of the scale factor serves as time, which has been studied in the context of the 'perfect bounce' for quantum cosmology. Unlike the first quantum theory, the second one contains semiclassical states that follow classical trajectories and evolve into the singularity without obstruction, thus showing no singularity resolution. We discuss how a complex scale factor best describes the semiclassical dynamics. This cosmological model serves as an illustration of the problem of time in quantum cosmology

The Promoter of the Cereal VERNALIZATION1 Gene Is Sufficient for Transcriptional Induction by Prolonged Cold

The VERNALIZATION1 (VRN1) gene of temperate cereals is transcriptionally activated by prolonged cold during winter (vernalization) to promote flowering. To investigate the mechanisms controlling induction of VRN1 by prolonged cold, different regions of the VRN1 gene were fused to the GREEN FLUORESCENT PROTEIN (GFP) reporter and expression of the resulting gene constructs was assayed in transgenic barley (Hordeum vulgare). A 2 kb segment of the promoter of VRN1 was sufficient for GFP expression in the leaves and shoot apex of transgenic barley plants. Fluorescence increased at the shoot apex prior to inflorescence initiation and was subsequently maintained in the developing inflorescence. The promoter was also sufficient for low-temperature induction of GFP expression. A naturally occurring insertion in the proximal promoter, which is associated with elevated VRN1 expression and early flowering in some spring wheats, did not abolish induction of VRN1 transcription by prolonged cold, however. A translational fusion of the promoter and transcribed regions of VRN1 to GFP, VRN1::GFP, was localised to nuclei of cells at the shoot apex of transgenic barley plants. The distribution of VRN1::GFP at the shoot apex was similar to the expression pattern of the VRN1 promoter-GFP reporter gene. Fluorescence from the VRN1::GFP fusion protein increased in the developing leaves after prolonged cold treatment. These observations suggest that the promoter of VRN1 is targeted by mechanisms that trigger vernalization-induced flowering in economically important temperate cereal crops

Genome-wide gene expression analysis supports a developmental model of low temperature tolerance gene regulation in wheat (Triticum aestivum L.)

<p>Abstract</p> <p>Background</p> <p>To identify the genes involved in the development of low temperature (LT) tolerance in hexaploid wheat, we examined the global changes in expression in response to cold of the 55,052 potentially unique genes represented in the Affymetrix Wheat Genome microarray. We compared the expression of genes in winter-habit (winter Norstar and winter Manitou) and spring-habit (spring Manitou and spring Norstar)) cultivars, wherein the locus for the vernalization gene <it>Vrn-A1 </it>was swapped between the parental winter Norstar and spring Manitou in the derived near-isogenic lines winter Manitou and spring Norstar. Global expression of genes in the crowns of 3-leaf stage plants cold-acclimated at 6°C for 0, 2, 14, 21, 38, 42, 56 and 70 days was examined.</p> <p>Results</p> <p>Analysis of variance of gene expression separated the samples by genetic background and by the developmental stage before or after vernalization saturation was reached. Using gene-specific ANOVA we identified 12,901 genes (at <it>p </it>< 0.001) that change in expression with respect to both genotype and the duration of cold-treatment. We examined in more detail a subset of these genes (2,771) where expression was highly influenced by the interaction between these two main factors. Functional assignments using GO annotations showed that genes involved in transport, oxidation-reduction, and stress response were highly represented. Clustering based on the pattern of transcript accumulation identified genes that were up or down-regulated by cold-treatment. Our data indicate that the cold-sensitive lines can up-regulate known cold-responsive genes comparable to that of cold-hardy lines. The levels of expression of these genes were highly influenced by the initial rate and the duration of the gene's response to cold. We show that the <it>Vrn-A1 </it>locus controls the duration of gene expression but not its initial rate of response to cold treatment. Furthermore, we provide evidence that <it>Ta.Vrn-A1 </it>and <it>Ta.Vrt1 </it>originally hypothesized to encode for the same gene showed different patterns of expression and therefore are distinct.</p> <p>Conclusion</p> <p>This study provides novel insight into the underlying mechanisms that regulate the expression of cold-responsive genes in wheat. The results support the developmental model of LT tolerance gene regulation and demonstrate the complex genotype by environment interactions that determine LT adaptation in winter annual cereals.</p

Genetic basis of the very short life cycle of ‘Apogee’ wheat

Background: ‘Apogee’ has a very short life cycle among wheat cultivars (flowering 25 days after planting under a long day and without vernalization), and it is a unique genetic material that can be used to accelerate cycling breeding lines. However, little is known about the genetic basis of the super-short life of Apogee wheat. Results: In this study, Apogee was crossed with a strong winter wheat cultivar ‘Overland’, and 858 F2 plants were generated and tested in a greenhouse under constant warm temperature and long days. Apogee wheat was found to have the early alleles for four flowering time genes, which were ranked in the order of vrn-A1 \u3e VRN-B1 \u3e vrn- D3 \u3e PPD-D1 according to their effect intensity. All these Apogee alleles for early flowering showed complete or partial dominance effects in the F2 population. Surprisingly, Apogee was found to have the same alleles at vrn-A1a and vrn-D3a for early flowering as observed in winter wheat cultivar ‘Jagger.’ It was also found that the vrn-A1a gene was epistatic to VRN-B1 and vrn-D3. The dominant vrn-D3a alone was not sufficient to cause the transition from vegetative to reproductive development in winter plants without vernalization but was able to accelerate flowering in those plants that carry the vrn-A1a or Vrn-B1 alleles. The genetic effects of the vernalization and photoperiod genes were validated in Apogee x Overland F3 populations. Conclusion: VRN-A1, VRN-B1, VRN-D3, and PPD-D1 are the major genes that enabled Apogee to produce the very short life cycle. This study greatly advanced the molecular understanding of the multiple flowering genes under different genetic backgrounds and provided useful molecular tools that can be used to accelerate winter wheat breeding schemes

RIMAPS Analysis of Filtered Images

This research work analyzes how RIMAPS spectrum varies when a filter is applied on the image of a leaf surface. The stylize filter from the Adobe Photoshop software program is used. This filter identifies the areas of the image with significant transitions and emphasizes the edges with dark lines against a white background and is useful for highlighting the borders of cells and papillae.Fil: Favret, Eduardo Alfredo. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pidal, Bárbara. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales; Argentin

Wheat Leaves: The Surface Disposition of Their Epicuticular Wax

This research work describes the micro-nano-patterning of the epicuticular wax of wheat leaf surface (adaxial side), by analyzing their RIMAPS spectra. It is known that the epicuticular wax of the wheat leaf has a platelet shape. The basic idea of this work is to see if the platelets have a specific arrangement on the surface, if they are disposed in certain directions. This concept is important because some studies concerning wheat leaf-Rust fungus interaction which were performed to investigate factors influencing fungus spore germination and growing, like leaf surface morphology and chemical components, showed that topological features and wax related components play a crucial role in the orientation of rust germination hyphae towards the stomata, probably modulated by chemical signals.Fil: Favret, Eduardo Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales; ArgentinaFil: Pidal, B.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales; Argentin