Trends and Anti-Trends in Techno-Art Scholarship: The Legacy of the Arts “Machine” Special Issues

With the goal of casting a spotlight on the posture of the creative community at this crucial moment in human technological history, we present herein a thematic overview of the 23 articles published in the recent Arts Special Issues “The Machine as Art (in the 20th Century)” and “The Machine as Artist (for the 21st Century)”. Surprisingly, several of the themes that had been suggested in our two introductory essays as representing shared and positive points of departure—in particular, (a) the visual arts as a longstanding touchstone of human culture, (b) the visual arts (with the example of John James Audubon) as having a unique ability to rally the public to the environmental cause, and (c) computer and robotic proficiency in the arts as leading to a friendlier artificial intelligence—received less than the expected amount of attention. Instead, it was another of the suggested themes (albeit also of a positive and forward-looking nature) around which our authors coalesced, as expressed in the following phrase: the “vast expansion of the creative sphere” which technology has made possible, or in other words, the idea that technology is not only providing new horizons for the professional artist but is also providing new avenues for the non-professional to discover his or her creative potential. In light, furthermore, of the marked enthusiasm for this theme, we suggest in our conclusion the need for a corresponding expansion of the venues available to both professional and non-professional techno-art practitioners

Chilling temperature remodels phospholipidome of Zea mays seeds during imbibition

International audienceGlobal warming is a major agricultural issue in the Northern hemisphere where higher temperatures are expected to be associated with restricted water availability. In Europe, for maize, earlier and further northward sowings are forecasted in order to avoid water deficit periods in the crop life cycle. However these conditions may compromise seed germination and stand establishment since they will take place at cold temperatures. It is urgent to better understand the molecular bases of response of germinating maize seeds to cold in order to design genotypes adapted to these novel agricultural practices. Here we have performed a global phospholipidomic study to profile changes in membrane reorganisation during seed imbibition at 10 °C of cold-tolerant and-sensitive maize hybrids. Using a Multiple Reaction Monitoring (MRM-MS/MS) method coupled with HPLC we have identified 80 distinct phospholipids. We show that seed sensitivity to cold temperatures during imbibition relies on the accumulation of saturated or poorly unsaturated fatty acids, whatever the phospholipid class. In contrast seeds of cold-tolerant hybrid accumulated polyunsaturated chains which was associated with lower electrolyte leakage during imbibition at 10 °C. The expression of fatty acid desaturase genes provides a molecular model of maize seed sensitivity to imbibitional chilling damage. In Europe maize is the second major crop and it represents almost a quarter of the total cereal production 1. South France, Italy, Hungary and Romania are the main areas for maize production thus forming a geographic belt where the environmental conditions are optimum for growth and development of this crop. Studies on climate change performed in the last decade show consistent projections of increases in temperatures and changes in precipitation patterns at the global scale 2. In temperate areas, warming is predicted to increase by 2 °C in 2030 and water stress will dramatically increase in the southern regions of Europe. Both phenomena are expected to greatly reduce maize crop yields especially because they will affect the phenological stages of flowering and grain maturation 3, 4. Therefore novel agricultural practices must be designed in order to counteract the negative impacts of climate change, while taking advantage of its positive effects. Creation of stress tolerant hybrids and modification of sowing dates, with the use of early maturing hybrids, are short terms options which are already implemented 5. In addition, land reallocation is a long-term adaptation which is more and more discussed 6, 7. Indeed, in Europe, a northern shift of maize production area would allow to prevent more adverse conditions and would permit maize crops not to suffer from water deficit during the critical steps of growing 8, 9. Although attractive, this strategy will however lead maize seeds to germinate and maize seedlings to grow in inappropriate thermal conditions encountered at the time of stand establishment in European northern regions. Maize is indeed naturally adapted to environmental conditions of tropical regions 5 and the base temperature (Tb) commonly used for this plant is 10 °C 10 , indicating that a temperature of 10 °C can be defined as " low " or " cold " for this species, as this is stated in this work. In consequence cooler temperatures of European northern areas are expected to greatly affect seed germination and seedling establishment of maize which could in consequence prevent the successful use of reallocation strategies. Seed germination is a complex and tightly regulated process which starts with water absorption by the dry seed and ends when radicle elongates 11. Its achievement requires a synchronized achievement of many cellular processes including DNA repair, protein synthesis or membrane reorganization 11, 12. In dry seeds membranes are in a gel state and if water enters the seed before their transition to a liquid crystalline state leakage and damage

Effects of environment factors on induction of secondary dormancy in relation with abscisic acid in barley grains

La dormance primaire des grains d orge correspond à une inaptitude à germer à l obscurité à des températures supérieures à 10-15C et la lumière bleue renforce cette dormance. L incubation des grains dans des conditions ne permettant pas leur germination (30C, hypoxie, lumière bleue) induit une perte de l aptitude à germer après leur transfert à 10 ou 15C, à l obscurité et dans l air. Ce phénomène qui correspond à une induction de dormance secondaire, est observé après 3 jours à 30C ou à 15C en hypoxie (5% O2) et après une exposition des grains à 10C en présence de lumière bleue d au moins 5 jours. A 30C, elle nécessite une teneur en eau supérieure à 0.50 g H2O g-1 MS et est associée à de fortes teneurs en ABA de l embryon après le transfert à 15C, alors que la teneur en ABA est peu affectée par l hypoxie. La lumière bleue entraîne une forte augmentation de la teneur en ABA des embryons et de leur sensibilité à l ABA et à l hypoxie. Le rôle d HvNCED1 (synthèse de l ABA) semble prépondérant pour l induction à 30C alors que celui d HvNCED2 est plus important en hypoxie, et l expression des 2 gènes est fortement induite par la lumière bleue. Dans tous les cas, l induction de la dormance secondaire est associée à une réduction de la signalisation des GA due à une augmentation de l expression de gènes impliqués dans leur catabolisme et une inhibition de ceux impliqués dans leur synthèse, HvGA2ox3 et HvGA3ox2 jouant un rôle prépondérant. Nos résultats montrent clairement l implication de la balance ABA/GA et que le profil d expression des gènes impliqués dans celle-ci dépend des facteurs environnementaux induisant la dormance secondairePrimary dormancy of barley seeds corresponds to an inability to germinate at temperatures higher than 10-15C, which is reinforced in presence of blue light. Incubation of grains in unfavourable conditions (30C, hypoxia, blue light) results in a loss of subsequent germination ability at 10 or 15C, in darkness and in air. This phenomenon considered as an induction of secondary dormancy, is observed after incubation of the grains for 3 days at 30 C or at 15C in hypoxia (5% O2), or for at least 5 days at 10C in the presence of blue light. At 30C, it requires an embryo water content higher than 0.50 g H2O g-1 DM, and is associated with an increase in embryo ABA content after transfer at 15C, while ABA content in slightly changed by hypoxia. Blue light results in a strong increase in embryo ABA content and in embryo sensitivity to ABA and hypoxia. The role of HvNCED1 (ABA synthesis) seems dominant in the induction at 30C, while HvNCED2 seems more important in the induction by hypoxia, and the expression of both genes is strongly induced by blue light. In all cases, the induction of secondary dormancy is associated with a reduction of GA signalling due to increased expression of genes involved in GA catabolism and inhibition of those involved in their synthesis, but HvGA2ox3 and HvGA3ox2 appear to play a leading role. Our results clearly show the involvement of the ABA/GA balance, and that the expression pattern of genes involved in ABA/GA metabolism depends on the environmental factors that induce secondary dormancyPARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF

Potential involvement of proline and flavonols in plant responses to ozone

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Germination Potential of Dormant and Nondormant Arabidopsis Seeds Is Driven by Distinct Recruitment of Messenger RNAs to Polysomes

International audienceDormancy is a complex evolutionary trait that temporally prevents seed germination, thus allowing seedling growth at a favorable season. High-throughput analyses of transcriptomes have led to significant progress in understanding the molecular regulation of this process, but the role of posttranscriptional mechanisms has received little attention. In this work, we have studied the dynamics of messenger RNA association with polysomes and compared the transcriptome with the translatome in dormant and nondormant seeds of Arabidopsis (Arabidopsis thaliana) during their imbibition at 25 degrees C in darkness, a temperature preventing germination of dormant seeds only. DNA microarray analysis revealed that 4,670 and 7,028 transcripts were differentially abundant in dormant and nondormant seeds in the transcriptome and the translatome, respectively. We show that there is no correlation between transcriptome and translatome and that germination regulation is also largely translational, implying a selective and dynamic recruitment of messenger RNAs to polysomes in both dormant and nondormant seeds. The study of 5' untranslated region features revealed that GC content and the number of upstream open reading frames could play a role in selective translation occurring during germination. Gene Ontology clustering showed that the functions of polysome-associated transcripts differed between dormant and nondormant seeds and revealed actors in seed dormancy and germination. In conclusion, our results demonstrate the essential role of selective polysome loading in this biological process

5' to 3' mRNA Decay Contributes to the Regulation of Arabidopsis Seed Germination by Dormancy

International audienceThe regulation of plant gene expression, necessary for development and adaptive responses, relies not only on RNA transcription but also on messenger RNA (mRNA) fate. To understand whether seed germination relies on the degradation of specific subsets of mRNA, we investigated whether the 5' to 3' RNA decay machinery participated in the regulation of this process. Arabidopsis (Arabidopsis thaliana) seeds of exoribonuclease4 (xrn4) and varicose (vcs) mutants displayed distinct dormancy phenotypes. Transcriptome analysis of xrn4-5 and vcs-8 mutant seeds allowed us to identify genes that are likely to play a role in the control of germination. Study of 59 untranslated region features of these transcripts revealed that specific motifs, secondary energy, and GC content could play a role in their degradation by XRN4 and VCS, and Gene Ontology clustering revealed novel actors of seed dormancy and germination. Several specific transcripts identified as being putative targets of XRN4 and VCS in seeds (PECTIN LYASE-LIKE, ASPARTYL PROTEASE, DWD-HYPERSENSITIVE-TO-ABA3, and YELLOW STRIPE-LIKE5) were further studied by reverse genetics, and their functional roles in the germination process were confirmed by mutant analysis. These findings suggest that completion of germination and its regulation by dormancy also depend on the degradation of specific subsets of mRNA

Catalase activity and expression in developing sunflower seeds as related to drying

International audienceChanges in catalase (CAT) activity and in CAT isoform pattern and expression were investigated in developing sunflower (Helianthus annuus L.) seeds during desiccation on the mother plant and after artificial drying on the flowerheads. Seeds regularly desiccated during their development on the mother plant and reached mass maturity at c. 42 d after flowering (DAF). Freshly harvested seeds did not germinate at any stage of development because they were dormant, but their dormancy was broken after 5-6 months of dry storage. Immature seeds were desiccation-tolerant at 24 DAF since they were able to germinate fully after artificial drying on the flowerheads followed by dry storage. CAT activity increased in non-dehydrated seeds during their development, reaching a maximum a little after seed mass maturity and after artificial drying in immature seeds. This stimulation of CAT activity by natural and artificial drying was related to changes in CAT isoform pattern. Of the four constitutive CAT subunits, that of 59 kDa was always present, but dehydration induced the synthesis of a 55 kDa subunit. This synthesis of the CAT 55 kDa subunit resulted from an activation of the CATA1 gene, suggesting that the regulation of catalase activity and synthesis by drying occurred at the transcriptional level. The increase in CAT activity induced by seed drying was associated with a decrease in hydrogen peroxide level and in lipid peroxidation. These results suggest that CAT plays a role during seed desiccation by preventing dehydration-related oxidative damage and that H(2)O(2) may play a role in the regulation of CAT gene expression and the transduction pathway of the dehydration signal