Pales Espinosa Emmanuelle, Allam Bassem
School of Marine and Atmospheric Sciences, State University of New York, Stony Brook, NY 11794, USA
School of Marine and Atmospheric Sciences, State University of New York, Stony Brook, NY 11794, USA.
J Exp Biol. 2018 Mar 14;221(Pt 6):jeb174094. doi: 10.1242/jeb.174094.
Prey selection governs species interactions and regulates physiological energetics of individuals and populations. Suspension-feeding bivalves represent key species in coastal and estuarine systems for their ecological and economic value. These animals are able to sort and selectively ingest nutritious microalgae from dilute and composite mixtures of particulate matter. This aptitude was suggested to be mediated by interactions between carbohydrates associated with the surface of microalgae and C-type lectins present in mucus covering the feeding organs, although a direct, unequivocal, role of lectins in food sorting in bivalves remains elusive. This study was designed to identify and characterize mucosal C-type lectins from oysters and manipulate the expression of these proteins in order to obtain decisive information regarding their involvement in food choice. Thus, two mucosal C-type lectins (CvML3912 and CvML3914) were identified based on transcriptomic and proteomic information. Transcripts of these lectins were detected in the feeding organs and their expression was upregulated following starvation. Recombinant lectin (rCvML3912) competitively inhibited the binding of commercial mannose/glucose-specific lectins to microalgae. Short Dicer-substrate small interfering RNA (DsiRNA) targeting these two lectins were designed and used to evaluate the effect of gene silencing on food particle sorting. As a result, the abundance of the two cognate transcripts significantly decreased and food sorting ability was significantly reduced among silenced oysters as compared with control animals. Overall, these findings propose a novel concept establishing the role of carbohydrate-protein interactions to provide efficient food particle sorting, and establish a new dimension for the role of evolutionarily conserved mannose/glucose-binding proteins in metazoans.
猎物选择支配着物种间的相互作用，并调节个体和种群的生理能量学。悬浮取食双壳贝类因其生态和经济价值，在沿海和河口系统中代表着关键物种。这些动物能够从稀释的颗粒物质复合混合物中筛选并选择性摄取营养丰富的微藻。有人认为，这种能力是由与微藻表面相关的碳水化合物和覆盖取食器官的黏液中存在的C型凝集素之间的相互作用介导的，尽管凝集素在双壳贝类食物筛选中的直接、明确作用仍不明确。本研究旨在鉴定和表征牡蛎的黏膜C型凝集素，并操纵这些蛋白质的表达，以获取有关它们参与食物选择的决定性信息。因此，基于转录组学和蛋白质组学信息鉴定出了两种黏膜C型凝集素（CvML3912和CvML3914）。在取食器官中检测到了这些凝集素的转录本，饥饿后其表达上调。重组凝集素（rCvML3912）竞争性抑制商业甘露糖/葡萄糖特异性凝集素与微藻的结合。设计了靶向这两种凝集素的短双链RNA干扰（DsiRNA），并用于评估基因沉默对食物颗粒筛选的影响。结果，与对照动物相比，沉默牡蛎中这两种同源转录本的丰度显著降低，食物筛选能力也显著降低。总体而言，这些发现提出了一个新概念，即碳水化合物-蛋白质相互作用在提供高效食物颗粒筛选方面的作用，并为后生动物中进化保守的甘露糖/葡萄糖结合蛋白的作用开辟了新的维度。
