title: Byssogenesis in the juvenile pink heelsplitter mussel, Potamilus alatus (Bivalvia: Unionidae).
abstract: The North American pink heelsplitter (Potamilus alatus) differs from most freshwater mussels in China by the ability to secrete an ephemeral byssus during its juvenile stage. In the present study, light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to investigate this ephemeral byssal structure, and amino acid composition was analyzed and compared with that of other species. The results revealed that the byssus consists of a long byssal thread and a few adhesive plaques which are randomly set up along the thread and assembled by petioles. There is a thin but distinctive cuticle with a continuous homogeneous matrix surrounding the byssal thread. Structural variation occurred when the byssal thread was differentially stretched. Four-stranded helical primary fasciculi, which form a stable rope-like structure, become evident after removal of the cuticle. The primary fasciculi consist of bundles of hundreds of parallel secondary fasciculi, each measuring about 5 μm in diameter. All evidence indicates that the byssus of the pink heelsplitter has a significantly different macrostructure and microstructure than the permanent byssus of the marine mussel Mytilus. Byssogenesis ceases when juveniles exceed 30 mm in length, although it varies greatly even among juveniles of similar size. Byssus formation is influenced by substrate type. The unique characteristics of the byssus have important advantages for survival, transition, and aggregation during the early life history. This study not only provides first insight into the structure of the ephemeral byssus and its relationship to freshwater mussel development and growth, but also suggests possibilities for the synthesis of novel biopolymer materials particularly useful in freshwater ecosystems.
authors: Wuxi Fishery College, Nanjing Agriculture University, Jiangsu, 214081, China.|Key Laboratory of Genetic Breeding and Aquaculture Biology of Freshwater Fishes, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.|Sino-US Cooperative Laboratory for Germplasm Conservation and Utilization of Freshwater Mollusks, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.
authors: Hai B
authors: HB
authors: Wen
authors: Sino-US Cooperative Laboratory for Germplasm Conservation and Utilization of Freshwater Mollusks, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.
authors: Dan
authors: D
authors: Hua
authors: Wuxi Fishery College, Nanjing Agriculture University, Jiangsu, 214081, China.|Key Laboratory of Genetic Breeding and Aquaculture Biology of Freshwater Fishes, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.|Sino-US Cooperative Laboratory for Germplasm Conservation and Utilization of Freshwater Mollusks, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.
authors: Xue Y
authors: XY
authors: Ma
authors: Key Laboratory of Genetic Breeding and Aquaculture Biology of Freshwater Fishes, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.|Sino-US Cooperative Laboratory for Germplasm Conservation and Utilization of Freshwater Mollusks, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.
authors: Wu
authors: W
authors: Jin
authors: Key Laboratory of Genetic Breeding and Aquaculture Biology of Freshwater Fishes, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.|Sino-US Cooperative Laboratory for Germplasm Conservation and Utilization of Freshwater Mollusks, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.
authors: Yan B
authors: YB
authors: Zhuang
authors: Wuxi Fishery College, Nanjing Agriculture University, Jiangsu, 214081, China.|Key Laboratory of Genetic Breeding and Aquaculture Biology of Freshwater Fishes, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.|Sino-US Cooperative Laboratory for Germplasm Conservation and Utilization of Freshwater Mollusks, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.
authors: Ruo B
authors: RB
authors: Gu
authors: Wuxi Fishery College, Nanjing Agriculture University, Jiangsu, 214081, China.|Key Laboratory of Genetic Breeding and Aquaculture Biology of Freshwater Fishes, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.|Sino-US Cooperative Laboratory for Germplasm Conservation and Utilization of Freshwater Mollusks, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.
authors: Xin H
authors: XH
authors: Yuan
authors: Wuxi Fishery College, Nanjing Agriculture University, Jiangsu, 214081, China.|Sino-US Cooperative Laboratory for Germplasm Conservation and Utilization of Freshwater Mollusks, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.
authors: Xin W
authors: XW
authors: Du
authors: Wuxi Fishery College, Nanjing Agriculture University, Jiangsu, 214081, China.|Key Laboratory of Genetic Breeding and Aquaculture Biology of Freshwater Fishes, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.|Sino-US Cooperative Laboratory for Germplasm Conservation and Utilization of Freshwater Mollusks, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Jiangsu, 214081, China.
authors: Pao
authors: P
authors: Xu
mesh_terms: D000596:Amino Acids / Q000032:analysis; D060105:Animal Shells / Q000033:anatomy & histology; D000825:Animal Structures / Q000033:anatomy & histology / Q000254:growth & development*; D000818:Animals; D009929:Organ Size; D038081:Organogenesis; D049876:Unionidae / Q000033:anatomy & histology*
chemical_list: D000596:Amino Acids
keywords: amino acid composition; cuticle; ephemeral byssus; microstructure; plaque