Dissecting the pathways coordinating patterning and growth by plant boundary domains.

Boundary domains play important roles during morphogenesis in plants and animals, but how they contribute to patterning and growth coordination in plants is not understood. The CUC genes determine the boundary domains in the aerial part of the plants and, in particular, they have a conserved role in regulating leaf complexity across Angiosperms. Here, we used tooth formation at the Arabidopsis leaf margin controlled by the CUC2 transcription factor to untangle intertwined events during boundary-controlled morphogenesis in plants. Combining conditional restoration of CUC2 function with morphometrics as well as quantification of gene expression and hormone signaling, we first established that tooth morphogenesis involves a patterning phase and a growth phase. These phases can be separated, as patterning requires CUC2 while growth can occur independently of CUC2. Next, we show that CUC2 acts as a trigger to promote growth through the activation of three functional relays. In particular, we show that KLUH acts downstream of CUC2 to modulate auxin response and that expressing KLUH can compensate for deficient CUC2 expression during tooth growth. Together, we reveal a genetic and molecular network that allows coordination of patterning and growth by CUC2-defined boundaries during morphogenesis at the leaf margin

Combining laser-assisted microdissection (LAM) and RNA-seq allows to perform a comprehensive transcriptomic analysis of epidermal cells of Arabidopsis embryo

Background: Genome- wide characterization of tissue- or cell-specific gene expression is a recurrent bottleneck in biology. We have developed a sensitive approach based on ultra-low RNA sequencing coupled to laser assisted microdissection for analyzing different tissues of the small Arabidopsis embryo. Methods and results: We first characterized the number of genes detected according to the quantity of tissue yield and total RNA extracted. Our results revealed that as low as 0.02 mm(2) of tissue and 50 pg of total RNA can be used without compromising the number of genes detected. The optimised protocol was used to compare the epidermal versus mesophyll cell transcriptomes of cotyledons at the torpedo- shaped stage of embryo development. The approach was validated by the recovery of well- known epidermal genes such AtML1 or AtPDF2 and genes involved in flavonoid and cuticular waxes pathways. Moreover, the interest and sensitivity of this approach were highlighted by the characterization of several transcription factors preferentially expressed in epidermal cells. Conclusion: This technical advance unlocks some current limitations of transcriptomic analyses and allows to investigate further and efficiently new biological questions for which only a very small amounts of cells need to be isolated. For instance, it paves the way to increasing the spatial accuracy of regulatory networks in developing small embryo of Arabidopsis or other plant tissues

Disruption of LACCASE4 and 17 Results in Tissue-Specific Alterations to Lignification of Arabidopsis thaliana Stems[W]

This study provides evidence that two laccases, LAC4 and LAC17, participate in the polymerization of lignins in Arabidopsis stems. These findings suggest that the genetic engineering of lignin-specific laccases is a potentially innovative and promising tool for the fine-tuning of lignin content and structure

Combining laser-assisted microdissection (LAM) and RNA-seq allows to perform a comprehensive transcriptomic analysis of epidermal cells of Arabidopsis embryo

Abstract Background Genome-wide characterization of tissue- or cell-specific gene expression is a recurrent bottleneck in biology. We have developed a sensitive approach based on ultra-low RNA sequencing coupled to laser assisted microdissection for analyzing different tissues of the small Arabidopsis embryo. Methods and results We first characterized the number of genes detected according to the quantity of tissue yield and total RNA extracted. Our results revealed that as low as 0.02 mm2 of tissue and 50 pg of total RNA can be used without compromising the number of genes detected. The optimised protocol was used to compare the epidermal versus mesophyll cell transcriptomes of cotyledons at the torpedo-shaped stage of embryo development. The approach was validated by the recovery of well-known epidermal genes such AtML1 or AtPDF2 and genes involved in flavonoid and cuticular waxes pathways. Moreover, the interest and sensitivity of this approach were highlighted by the characterization of several transcription factors preferentially expressed in epidermal cells. Conclusion This technical advance unlocks some current limitations of transcriptomic analyses and allows to investigate further and efficiently new biological questions for which only a very small amounts of cells need to be isolated. For instance, it paves the way to increasing the spatial accuracy of regulatory networks in developing small embryo of Arabidopsis or other plant tissues

Histologie, dégradabilité de la biomasse lignocellulosique et tolérance des plantes à un manque d'eau.

International audienceLa dégradabilité des parois est en tout premier lieu limitée par la teneur en lignine. Il n'est cependant pas possible d'améliorer cette dégradabilité en diminuant drastiquement la lignification des parois sans impacter fortement sur le rendement et les résistances des plantes aux parasites ou aux conditions environnementales. Nous recherchons donc quels autres facteurs peuvent être ciblés pour améliorer la dégradabilité des parois. La répartition des tissus lignifiés au sein des tiges est une de ces cibles prometteuses. D'autre part, dans le contexte agro-climatique actuel, nous recherchons quels facteurs peuvent conférer aux plantes une meilleure réponse au manque d'eau. Là encore, nous pensons que la répartition des tissus lignifiés au sein des tiges est une cible importante. C'est pour cela que nous développons, au sein de notre équipe, des approches de caractérisation histologique des tiges afin de relier les paramètres décrivant le mieux la répartition des tissus lignifiés aux variations de dégradabilité des parois ou à la tolérance à une disponibilité en eau limitante. Ce poster présente de façon synthétique les outils développés en analyse d'images [1-2], ainsi que les résultats majeurs obtenus dans le cadre d'une dizaine de projets visant à mieux comprendre les variations de dégradabilité de paroi [3-4], la mise en place des tissus lignifiés au sein des tiges durant le développement des plantes [5-6] ou encore la tolérance au déficit hydrique [7] chez le maïs, le miscanthus ou Arabidopsis thaliana. Cette synthèse se conclue par la mise en avant des principales cibles histologiques permettant de moduler la qualité de la biomasse lignocellulosique et d'offrir aux plantes une meilleure tolérance au manque d'eau

Histologie, dégradabilité de la biomasse lignocellulosique et tolérance des plantes à un manque d'eau.

International audienceLa dégradabilité des parois est en tout premier lieu limitée par la teneur en lignine. Il n'est cependant pas possible d'améliorer cette dégradabilité en diminuant drastiquement la lignification des parois sans impacter fortement sur le rendement et les résistances des plantes aux parasites ou aux conditions environnementales. Nous recherchons donc quels autres facteurs peuvent être ciblés pour améliorer la dégradabilité des parois. La répartition des tissus lignifiés au sein des tiges est une de ces cibles prometteuses. D'autre part, dans le contexte agro-climatique actuel, nous recherchons quels facteurs peuvent conférer aux plantes une meilleure réponse au manque d'eau. Là encore, nous pensons que la répartition des tissus lignifiés au sein des tiges est une cible importante. C'est pour cela que nous développons, au sein de notre équipe, des approches de caractérisation histologique des tiges afin de relier les paramètres décrivant le mieux la répartition des tissus lignifiés aux variations de dégradabilité des parois ou à la tolérance à une disponibilité en eau limitante. Ce poster présente de façon synthétique les outils développés en analyse d'images [1-2], ainsi que les résultats majeurs obtenus dans le cadre d'une dizaine de projets visant à mieux comprendre les variations de dégradabilité de paroi [3-4], la mise en place des tissus lignifiés au sein des tiges durant le développement des plantes [5-6] ou encore la tolérance au déficit hydrique [7] chez le maïs, le miscanthus ou Arabidopsis thaliana. Cette synthèse se conclue par la mise en avant des principales cibles histologiques permettant de moduler la qualité de la biomasse lignocellulosique et d'offrir aux plantes une meilleure tolérance au manque d'eau

Potter and Perry's Fundamentals of Nursing: Australia and New Zealand.[ 6th ed.]

Now in its 6th edition, this trusted reference for nursing students supports the development of safe, effective and person-centred practice.The text has been comprehensively revised by nursing leaders and experts from across the spectrum of clinical practice, education, research and health policy settings; and a highly experienced editorial team, which includes Jackie Crisp, Clint Douglas, Geraldine Rebeiro and Donna Waters.Chapters engage students with contemporary concepts and clinical examples, designed to build clinical reasoning skills. Early chapters introduce frameworks such as Fundamentals of Care and cultural safety, as ways of being and practising as a nurse. These frameworks are then applied in clinical and practice context chapters throughout. Reflection points in each chapter encourage curiosity and creativity in learning, including the importance of self-care and self-assessment

The cell expansion defects of the <i>exi</i> mutants are rescued by liquid culture.

<p>(A–H) Leaf mesophyll of the <i>exi</i> mutants. Diagrams were drawn from differential interference contrast micrographs of cleared first-node leaves collected from (A, E) L<i>er</i>, (B, F) <i>exi1-2</i>, (C, G) <i>exi2</i> and (D, H) <i>exi5</i> plants. (I, J) First-node leaf (I) lamina area and (J) mesophyll cell area in the <i>exi</i> mutants. Data were normalized with respect to the L<i>er</i> values and are expressed as percentages (mean and standard deviation). Asterisks indicate significant differences from the control seedlings grown on half-strength MS agar medium (<i>P</i> value<0.01). All the data were obtained 21 DAS from seedlings grown on half-strength MS agar plates (A–D, white bars) or in half-strength MS liquid cultures (E–H, grey bars). Scale bars indicate 50 µm.</p

Xylem structure and composition in <i>exi</i> stems.

<p>(A–D) Scanning electron micrographs of transverse sections of stems from (A, A′) L<i>er</i>, (B, B′) <i>exi1-2</i>, (C, C′) <i>exi2</i> and (D, D′) <i>exi5</i> plants. Magnification is (A–C) 70x and (A’–C’) 500x. (E–F) Comparison of the Fourier transform infrared spectroscopy spectra obtained from stem sections of L<i>er</i> and <i>exi</i> plants. Spectra were acquired on xylem in apical (E) and basal (F) parts of the stem. The value between the two red lines (threshold) corresponds to non-significant differences (<i>P</i> value<0.01) between the two genotypes tested. Significant positive <i>t</i>-values indicated a higher absorbance value in L<i>er</i> than in the <i>exi</i> mutants.</p