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Environ Microbiol

Title:		Colony induction and growth inhibition in Desmodesmus quadrispina (Chlorococcales) by allelochemicals released from the filamentous alga Uronema confervicolum (Ulotrichales)
Author(s):		Leflaive J; Lacroix G; Nicaise Y; Ten-Hage L;
Address:		"Laboratoire d'Ecologie Fonctionnelle (EcoLab), UMR 5245 (CNRS, UPS, INPT) Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse cedex 09, France. leflaive@cict.fr"
Journal Title:		Environ Microbiol
Year:		2008
Volume:		20080227
Issue:		6
Page Number:		1536 - 1546
DOI:		10.1111/j.1462-2920.2008.01569.x
ISSN/ISBN:		1462-2920 (Electronic) 1462-2912 (Linking)
Abstract:		"In biofilms, the competition between microorganisms for light, nutrients and space is extreme. Moreover, planktonic algae can be considered as competitors insofar as they decrease the available light for the benthic algae. One of the strategies employed by microorganisms to eliminate competitors is the release of inhibiting compounds, a process known as allelopathy. Here we demonstrate that a benthic/epiphytic alga, Uronema confervicolum, produces allelopathic compounds that induce oxidative stress and growth inhibition in the planktonic Desmodesmus quadrispina. Some of these compounds can also trigger the formation of colony in D. quadrispina. As colonies have higher sedimentation rates than unicells, their induction by U. confervicolum might decrease shading. This study is the first report of colony induction in the context of alga-alga interaction. Our results also suggest the implication of mitogen-activated protein (MAP) kinases in the transduction of the signal leading to the formation of reactive oxygen species in the cells. A comparison with allelochemicals from another planktonic green alga, Monoraphidium aff. dybowski, emphasizes the specificity of colony induction by U. confervicolum, in contrast with oxidative stress which is induced by several compounds. The reciprocal production of inhibiting compounds by D. quadrispina makes this interaction an interesting example of co-evolution between two microorganisms belonging to different compartments of the ecosystem"
Keywords:		Chlorophyta/*drug effects/growth & development/*metabolism Mitogen-Activated Protein Kinases/metabolism Oxidative Stress Pheromones/*metabolism Reactive Oxygen Species/metabolism;
Notes:		"MedlineLeflaive, Josephine Lacroix, Gerard Nicaise, Yvan Ten-Hage, Loic eng England 2008/03/04 Environ Microbiol. 2008 Jun; 10(6):1536-46. doi: 10.1111/j.1462-2920.2008.01569.x. Epub 2008 Feb 27"