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First published online January 18, 2008
Journal of Experimental Biology 211, 370-376 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.013458

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Swarm formation in the desert locust Schistocerca gregaria: isolation and NMR analysis of the primary maternal gregarizing agent

Gabriel A. Miller^1,2, M. Saiful Islam^2,3, Timothy D. W. Claridge⁴, Tim Dodgson¹ and Stephen J. Simpson^1,2,*

¹ School of Biological Sciences, The University of Sydney, Heydon-Laurence Building A08, NSW 2006, Australia
² Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
³ Department of Zoology, University of Rajshahi, Rajshahi 6205, Bangladesh
⁴ Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QH, UK

^* Author for correspondence (e-mail: stephen.simpson{at}bio.usyd.edu.au)

Accepted 12 November 2007

Depending on their rearing density, female desert locusts Schistocerca gregaria epigenetically endow their offspring with differing phenotypes. To identify the chemical basis for such maternal transmission, we compared solitarious and gregarious locust egg pod foam using high performance liquid chromatography (HPLC). We revealed causal relationships between foam chemistry and hatchling phenotype (phase state) by iteratively applying HPLC fractions from gregarious locust egg foam extracts to solitarious eggs and assessing resulting hatchlings with a behavioural bioassay involving logistic regression. Selection and application of increasingly specific HPLC fractions allowed us to isolate compounds with gregarizing properties. Hatchling gregarization was triggered only by certain fractions and was dose dependent. In a final series of experiments, we characterized the most specific gregarizing fraction by nuclear magnetic resonance (NMR) spectroscopy. Here we present tentative structural features of the primary locust maternal gregarizing agent, which appears to be an alkylated L-dopa analogue. In addition, we propose a mechanism for phase-dependent regulation of this compound's activity.

Key words: gregarizing factor, L-dopa, locust phase, change, maternal effect, NMR spectroscopy, phenotypic plasticity