Effects of Daphnia ‐Associated Infochemicals on the Morphology, Polysaccharides Content and PSII‐Efficiency in Scenedesmus obliquus

Abstract

We investigated the effects of infochemicals from Daphnia carinata on the morphology, polysaccharides yield and PSII-efficiency in Scenedesmus obliquus. Infochemicals released from D. carinata induced colony formation in S. obliquus. The contents of soluble extracellular polysaccharides, bounded extracellular polysaccharides, and the total polysaccharides per cell in the induced colonies of S. obliquus increased significantly relative to those of the unicells, which indicated that Daphnia-associated infochemicals could also stimulate S. obliquus to increase the synthesis of extracellular polysaccharides. The increased extracellular polysaccharides may play an important role in cementing S. obliquus cells together to form colonies. In addition, no significant differences in growth, the maximal efficiency of PSII photochemistry (F v /F m ), and the effective quantum yields of PSII (Φ PSII ) were detected between unicellular and induced colonial populations, which showed that the cost of induced colony formation was not reflected on these indices.

Waterborne copper impairs grazer-induced colony formation and photosynthetic efficiency inScenedesmus obliquus

“…Among the molecules found in cell walls (e.g., proteins and lipids), polysaccharides can bind metal ions and protect cells against metal ion toxicity (Bitton and Freihofer ; Cervantes and Gutierrez‐Corona ; Andrade et al ). However, during grazer‐induced colony formation, increase in polysaccharides is also known to affect cell adhesion and contribute to aggregation in algae (Thornton ; Yang et al ). Thus, polysaccharides used for increasing colony size may be inhibited or destroyed by Cu 2+ toxicity, and this effect may account for the decrease in the proportions of big‐sized colonies observed in the present study.…”

Interspecific variation in extracellular polysaccharide content and colony formation of Microcystis spp. cultured under different light intensities and temperatures

“…Moreover, colony formation depends on the species of the grazing zooplankton (Yang et al 2006). Grazers release info-chemicals that stimulate extracellular polysaccharide (EPS) production by Microcystis and subsequent colony formation (Yang et al 2005(Yang et al , 2007. Later studies identified other biotic inducers of Microcystis colonies, such as heterotrophic bacteria (Shen et al 2011), the filamentous cyanobacterium Cylindrospermopsis raciborskii (e Mello et al 2012), and microcystin (Gan et al 2012).…”

Combined effects of nitrogen levels and Daphnia culture filtrate on colony size of Scenedesmus obliquus

“…The colony formation of S. obliquus in this study was likely a consequence of increased polysaccharide content in cells, as demonstrated in other studies [16,17]. Moreover, nitrate stress can possibly induce an increase in carbohydrate content [18]; excess carbohydrate is preferentially channeled by algal cells to synthesize high amounts of products, such as polysaccharides [19], thereby contributing to cell aggregation.…”