ABSTRACT

Lectins are a large and diverse group of sugar-binding proteins involved in nonself recognition and cell-to-cell interactions. Suspension-feeding bivalves, such as the oyster Crassostrea virginica, are capable of using these molecules to bind cell surface carbohydrates of food particles, allowing particle capture and selection. The aim of this project was to assess whether the expression of mucosal lectins in C. virginica is constant or changes with the season, and to determine whether lectin expression is linked to environmental parameters and/or internal biological factors (gametogenesis). A total of 130 oysters were placed in submerged cages at a tidal estuary and monitored for changes in lectin gene expression over a 1-year period. In parallel, environmental parameters prevailing at the field site, including seawater physicochemical characteristics (temperature, salinity and dissolved oxygen), particulate organic matter and chlorophyll contents, were also monitored. Throughout the study, oysters were dissected and the gills were collected and used for the assessment of the expression of three different lectin genes (CvML, CvML3914 and CvML3912). Remaining tissues were processed for histology and the classification of the gonad development stage. Results showed that when food is abundant, such as during the spring bloom, lectin gene expressions are low, and inversely lectin levels increase with lower food levels. These findings suggest that oysters increase lectin expression to enhance the capture and ingestion of scarce food, while during spring, enough food is already being ingested and lectins are not needed. Furthermore, results showed that as the energy demands of oysters increase (gonad maturation), lectin gene expressions also increase to enhance selective ingestion of nutritious food particles. This study, therefore, demonstrates the seasonality of lectin gene expression in C. virginica, and suggests that lectin regulation is related to the reproduction process and abundance of high-quality food.

中文翻译：

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牡蛎Crassostrea virginica中的黏膜凝集素对食物供应和环境因素的响应

摘要

凝集素是参与非自我识别和细胞间相互作用的一大类糖结合蛋白。诸如牡蛎牡蛎（Crassostrea virginica）之类的悬浮饲喂双壳类动物能够利用这些分子结合食物颗粒的细胞表面碳水化合物，从而实现颗粒的捕获和选择。该项目的目的是评估粘膜凝集素是否在维吉尼亚念珠菌中表达是恒定的还是随季节变化的，并确定凝集素的表达是否与环境参数和/或内部生物学因素（配子发生）相关。将总共​​130只牡蛎放在潮汐河口的淹没笼中，并在1年的时间内监测凝集素基因表达的变化。同时，还监测了现场现场普遍存在的环境参数，包括海水的理化特性（温度，盐度和溶解氧），颗粒有机物和叶绿素含量。在整个研究中，解剖牡蛎并收集collected，用于评估三种不同凝集素基因（CvML，CvML3914和CvML3912）的表达。剩余的组织经过处理以进行组织学和性腺发育阶段的分类。结果表明，当食物丰富时，例如在春季开花期间，凝集素基因表达较低，而反之，凝集素水平则随着食物水平的降低而增加。这些发现表明，牡蛎增加了凝集素的表达，以增强稀有食物的捕获和摄取，而在春季，已经摄取了足够的食物，不需要凝集素。此外，结果表明，随着牡蛎能量需求的增加（性腺成熟），凝集素基因的表达也增加，从而增强了营养食物颗粒的选择性摄入。因此，这项研究证明了植物凝集素基因表达的季节性。这些发现表明，牡蛎增加了凝集素的表达，以增强稀有食物的捕获和摄取，而在春季，已经摄取了足够的食物，不需要凝集素。此外，结果表明，随着牡蛎能量需求的增加（性腺成熟），凝集素基因的表达也增加，从而增强了营养食物颗粒的选择性摄入。因此，这项研究证明了植物凝集素基因表达的季节性。这些发现表明，牡蛎增加了凝集素的表达，以增强稀有食物的捕获和摄取，而在春季，已经摄取了足够的食物，不需要凝集素。此外，结果表明，随着牡蛎能量需求的增加（性腺成熟），凝集素基因的表达也增加，从而增强了营养食物颗粒的选择性摄入。因此，这项研究证明了植物凝集素基因表达的季节性。C. virginica，并建议凝集素调节与优质食品的繁殖过程和丰富度有关。