Nematodes as important source for omega-3 long-chain fatty acids in the soil food web and the impact in nutrition for higher trophic levels
Animal Physiology and Biochemistry
Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems
Final Report Abstract
Many invertebrate species possess the metabolic ability to synthesize long-chain ω3 polyunsaturated fatty acids (PUFA) de novo. Due to their diverse effects on membrane architecture, neuroplasticity, growth and reproduction, PUFA have a high potential to positively influence the fitness of an organism. But how and when do these supposed advantages actually come into play? Other species, that are often closely related, pass natural selection without this special metabolic ability. The ω3-PUFA rich model organism Caenorhabditis elegans (Nematoda) and its mutant fat-1(wa9), lacking these PUFA, are a suitable test system. This project analyzed potential impairments in reproduction and growth in a soil assay. Further, chemotaxis after aversive olfactory, associative learning and integration of a second sensory signal were assessed on agar plates. Moreover, the phospholipid pattern of both C. elegans strains and further free-living nematodes species have been analyzed at different temperatures. While the phenotypic effects were rather small under standard conditions, lowering the temperature to 15 or even 10°C or reducing the soil moisture, led to significant limitations, with the investigated parameters for neuroplasticity being most impaired. The ω3-PUFA free C. elegans mutant strain fat-1 did not adapt the fatty acid composition of its phospholipids to a decreasing temperature, while ω3-PUFA containing nematodes proportionally increased this PUFA group. In contrast, other ω3-PUFA free nematode species produced significantly more ω6-PUFA. Thus, the ability to synthesize long-chain ω3-PUFA de novo likely is fundamental for an increase in neuroplasticity and an efficient way for regulating membrane fluidity to maintain their functionality. However, besides C. elegans, the distribution of this anabolic capacity among different invertebrate groups and its implementation at the gene and protein level are often still unknown. This project also investigated the PUFA pathways in common soil fauna, i.e. two nematode and two Collembola species. Of these, one species each (Panagrellus redivivus, Folsomia candida) was assumed to produce ω3 LC-PUFA de novo, while the others (Acrobeloides bodenheimeri, Isotoma caerulea) were supposed to be unable to do so. A highly labeled oleic acid (99% C) was supplemented and the isotopic signal was used to trace its metabolic path. All species followed the main pathway of lipid biosynthesis. However, in A. bodenheimeri this terminated at arachidonic acid (ω6 PUFA), whereas the other three species continued the pathway to eicosapentaenoic acid (ω3 PUFA), including I. caerulea. For the nematode P. redivivus the identification and functional characterization of four new fatty acid desaturase (FAD) genes was performed. These genes encode the FAD activities Δ9, Δ6, and Δ5, respectively. Additionally, the Δ12 desaturase was analyzed, yet the observed activity of an ω3 FAD could not be attributed to a coding gene. In the Collembola F. candida, 11 potential first desaturases (Δ9) and at least 15 front-end desaturases (Δ6 or Δ5 FADs) have been found. Further sequence analysis indicates the presence of omega FADs, specifically Δ12, which are likely derived from Δ9 FADs.
Publications
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Community Level Lipid Profiling in Soil Food Webs – Differences in Omega-3 Polyunsaturated Fatty Acids Across Trophic Levels and Forest Types.
Rissmann, Cornelia; Ruess, Liliane & Menzel, Ralph
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Serotonin-induced stereospecific formation and bioactivity of the eicosanoid 17,18-epoxyeicosatetraenoic acid in the regulation of pharyngeal pumping of C. elegans. Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids, 1868(5), 159304.
Zhou, Yiwen; Rothe, Michael; Schunck, Wolf-Hagen; Ruess, Liliane & Menzel, Ralph
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Dissection of the synthesis of polyunsaturated fatty acids in nematodes and Collembola of the soil fauna. Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids, 1869(8), 159541.
Menzel, Ralph; Tobias, Kevin; Fidan, Tugce; Rietz, Alexandra & Ruess, Liliane
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Omega-3 PUFA and the fitness and cognition of the nematode Caenorhabditis elegans under different environmental conditions. Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 270, 110925.
Menzel, Ralph; Zhang, Xuchao; Pietrucik, Tamara; Bathelt, Antonia & Ruess, Liliane
