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Author (up) Llorens, C.; Argentina, M.; Rojas, N.; Westbrook, J.; Dumais, J.; Noblin, X.
Title The fern cavitation catapult: mechanism and design principles Type
Year 2016 Publication Journal Of The Royal Society Interface Abbreviated Journal J. R. Soc. Interface
Volume 13 Issue 114 Pages 13 pp
Keywords leptosporangium; catapult; optimal design; cavitation; poroelasticity
Abstract Leptosporangiate ferns have evolved an ingenious cavitation catapult to disperse their spores. The mechanism relies almost entirely on the annulus, a row of 12-25 cells, which successively: (i) stores energy by evaporation of the cells' content, (ii) triggers the catapult by internal cavitation, and (iii) controls the time scales of energy release to ensure efficient spore ejection. The confluence of these three biomechanical functions within the confines of a single structure suggests a level of sophistication that goes beyond most man-made devices where specific structures or parts rarely serve more than one function. Here, we study in detail the three phases of spore ejection in the sporangia of the fern Polypodium aureum. For each of these phases, we have written the governing equations and measured the key parameters. For the opening of the sporangium, we show that the structural design of the annulus is particularly well suited to inducing bending deformations in response to osmotic volume changes. Moreover, the measured parameters for the osmoelastic design lead to a near-optimal speed of spore ejection (approx. 10 m s(-1)). Our analysis of the trigger mechanism by cavitation points to a critical cavitation pressure of approximately -100 +/- 14 bar, a value that matches the most negative pressures recorded in the xylem of plants. Finally, using high-speed imaging, we elucidated the physics leading to the sharp separation of time scales (30 versus 5000 μs) in the closing dynamics. Our results highlight the importance of the precise tuning of the parameters without which the function of the leptosporangium as a catapult would be severely compromised.
Address [Llorens, C.; Noblin, X.] Univ Nice Sophia Antipolis, CNRS UMR 7336, Phys Mat Condensee Lab, Parc Valrose, F-06108 Nice 2, France, Email: xavier.noblin@unice.fr
Corporate Author Thesis
Publisher Royal Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1742-5689 ISBN Medium
Area Expedition Conference
Notes WOS:000374959000011 Approved
Call Number UAI @ eduardo.moreno @ Serial 619
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Author (up) Loira, N.; Mendoza, S.; Cortes, M.P.; Rojas, N.; Travisany, D.; Di Genova, A.; Gajardo, N.; Ehrenfeld, N.; Maass, A.
Title Reconstruction of the microalga Nannochloropsis salina genome-scale metabolic model with applications to lipid production Type
Year 2017 Publication Bmc Systems Biology Abbreviated Journal BMC Syst. Biol.
Volume 11 Issue Pages 17 pp
Keywords Genome-scale Metabolic model; Nannochloropsis salina; TAG; Microalg ae
Abstract Background: Nannochloropsis salina (= Eustigmatophyceae) is a marine microalga which has become a biotechnological target because of its high capacity to produce polyunsaturated fatty acids and triacylglycerols. It has been used as a source of biofuel, pigments and food supplements, like Omega 3. Only some Nannochloropsis species have been sequenced, but none of them benefit from a genome-scale metabolic model (GSMM), able to predict its metabolic capabilities. Results: We present iNS934, the first GSMM for N. salina, including 2345 reactions, 934 genes and an exhaustive description of lipid and nitrogen metabolism. iNS934 has a 90% of accuracy when making simple growth/no-growth predictions and has a 15% error rate in predicting growth rates in different experimental conditions. Moreover, iNS934 allowed us to propose 82 different knockout strategies for strain optimization of triacylglycerols. Conclusions: iNS934 provides a powerful tool for metabolic improvement, allowing predictions and simulations of N. salina metabolism under different media and genetic conditions. It also provides a systemic view of N. salina metabolism, potentially guiding research and providing context to -omics data.
Address [Loira, Nicolas; Mendoza, Sebastian; Paz Cortes, Maria; Travisany, Dante; Di Genova, Alex; Maass, Alejandro] Univ Chile, Ctr Math Modeling, Math, Beauchef 851,7th Floor, Santiago, Chile, Email: nloira@dim.uchile.cl
Corporate Author Thesis
Publisher Biomed Central Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1752-0509 ISBN Medium
Area Expedition Conference
Notes WOS:000404918700001 Approved
Call Number UAI @ eduardo.moreno @ Serial 744
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