Neighbor Detection Induces Organ-Specific Transcriptomes, Revealing Patterns Underlying Hypocotyl-Specific Growth.

In response to neighbor proximity, plants increase the growth of specific organs (e.g., hypocotyls) to enhance access to sunlight. Shade enhances the activity of Phytochrome Interacting Factors (PIFs) by releasing these bHLH transcription factors from phytochrome B-mediated inhibition. PIFs promote elongation by inducing auxin production in cotyledons. In order to elucidate spatiotemporal aspects of the neighbor proximity response, we separately analyzed gene expression patterns in the major light-sensing organ (cotyledons) and in rapidly elongating hypocotyls of Arabidopsis thaliana PIFs initiate transcriptional reprogramming in both organs within 15 min, comprising regulated expression of several early auxin response genes. This suggests that hypocotyl growth is elicited by both local and distal auxin signals. We show that cotyledon-derived auxin is both necessary and sufficient to initiate hypocotyl growth, but we also provide evidence for the functional importance of the local PIF-induced response. With time, the transcriptional response diverges increasingly between organs. We identify genes whose differential expression may underlie organ-specific elongation. Finally, we uncover a growth promotion gene expression signature shared between different developmentally regulated growth processes and responses to the environment in different organs

Produção orgânica de calêndula: um estudo de caso.

Apresenta-se caracterização do processo de produção agrícola orgânica de Calendula officinalis L. no Estado de Santa Catarina, evidenciando particularidades e discrepâncias frente aos modelos já descritos na literatura especializada, a partir de visitas a campo, observação participante e entrevistas com um produtor de plantas medicinais. Identificaram-se como principais particularidades a saúde na agricultura familiar, demonstrada pela prática da cultura orgânica, além do controle de pragas e manuseio da produção. Os principais problemas ou divergências evidenciados foram: características do solo; época de plantio da calêndula e suas etapas posteriores, como transplante e floração. Aspectos da colheita foram discrepantes quanto ao período do dia indicado para o procedimento, bem como a ausência de informações do produtor quanto à existência de outros incentivos governamentais ao setor agrícola. Recomenda-se aos extensionistas rurais e/ou instituições competentes que busquem orientar os produtores orgânicos de calêndula para promover a adequação das práticas de cultivo dessa espécie medicinal

x−x-dependence of the quark distribution functions in the χ\chiCQMconfig_{{\rm config}}

Chiral constituent quark model with configuration mixing (\chiCQM_{{\rm config}}) is known to provide a satisfactory explanation of the ``proton spin problem'' and related issues. In order to enlarge the scope of \chiCQM_{{\rm config}}, we have attempted to phenomenologically incorporate x-dependence in the quark distribution functions. In particular, apart from calculating valence and sea quark distributions q_{{\rm val}}(x) and \bar q(x), we have carried out a detailed analysis to estimate the sea quark asymmetries \bar d(x)-\bar u(x), \bar d(x)/\bar u(x) and \frac{\bar d(x)-\bar u(x)}{u(x)-d(x)} as well as spin independent structure functions F_2^p(x)-F_2^n(x) and $F_2^n(x)/F_2^p(x)$ as functions of $x$. We are able to achieve a satisfactory fit for all the above mentioned quantities simultaneously. The inclusion of effects due to configuration mixing have also been examined in the case F_2^p(x)-F_2^n(x) and F_2^n(x)/F_2^p(x) where the valence quark distributions dominate and it is found that it leads to considerable improvement in the results. Further, the valence quark structure has also be tested by extrapolating the predictions of our model in the limit x \to 1 where data is not available.Comment: 20 pages, 7 figures. To appear in Eur. Phys. J.

A phosphorylation switch turns a positive regulator of phototropism into an inhibitor of the process.

Phototropins are light-activated protein kinases, which contribute to photosynthesis optimization both through enhancement of photon absorption when light is limiting and avoidance responses in high light. This duality is in part endowed by the presence of phototropins with different photosensitivity (phot1 and phot2). Here we show that phot1, which senses low light to promote positive phototropism (growth towards the light), also limits the response in high light. This response depends in part on phot1-mediated phosphorylation of Phytochrome Kinase Substrate 4 (PKS4). This light-regulated phosphorylation switch changes PKS4 from a phototropism enhancer in low light to a factor limiting the process in high light. In such conditions phot1 and PKS4 phosphorylation prevent phototropic responses to shallow light gradients and limit phototropism in a natural high light environment. Hence, by modifying PKS4 activity in high light the phot1-PKS4 regulon enables appropriate physiological adaptations over a range of light intensities

Nucleolar Organiser Regions Of Mesothelial And Carcinomatous Cells In Effusions

[No abstract available]9549249