Project description:To adhere their silk threads for the construction of webs and to fix the dragline, spiders produce attachment discs of piriform silk. Uniquely, the aquatic spider Argyroneta aquatica spends its entire life cycle underwater. Therefore, it has to glue its attachment discs to substrates underwater. Here we show that Argyroneta aquatica applies its thread anchors within an air layer around the spinnerets maintained by superhydrophobic setae. During spinning, symmetric movements of the spinnerets ensure retaining air in the contact area. The flat structure of the attachment discs is thought to facilitate fast curing of the piriform adhesive cement and improves the resistance against drag forces. Pull-off tests on draglines connected with attachment discs on different hydrophilic substrates point to dragline rupture as the failure mode. The Young´s modulus of the dragline (8.3 GPa) is within the range as in terrestrial spiders. The shown structural and behavioral adaptations can be the model for new artificial underwater gluing devices.
Project description:In this study, we characterized the fatty acid production in Neochloris aquatica at transcriptomics and biochemical levels under limiting, normal, and excess nitrate concentrations in different growth phases. At the stationary phase, N. aquatica mainly produced saturated fatty acids such as stearic acid under the limiting nitrate concentration, which is suitable for biodiesel production. However, it produced polyunsaturated fatty acids such as α-linolenic acid under the excess nitrate concentration, which has nutritional values as food supplements. In addition, RNA-seq was employed to identify genes and pathways that were being affected in N. aquatica for three growth phases in the presence of the different nitrate amounts. Genes that are responsible for the production of saturated fatty acids were upregulated in the cells grown under a limiting nitrogen amount while genes that are responsible for the production of polyunsaturated fatty acid were upregulated in the cells grown under excess nitrogen amount. Further analysis showed more genes differentially expressed (DEGs) at the loga- rithmic phase in all conditions while a relatively steady trend was observed during the transition from the logarithmic phase to the stationary phase under limiting and excess nitrogen. Our results provide a foundation for identifying developmentally important genes and understanding the biological processes in the different growth phases of the N. aquatica in terms of biomass and lipid production.