In vitro culture of glochidia from the freshwater mussel Anodonta cygnea
Larvae of the freshwater swan mussel, Anodonta cygnea, were cultured in artificial media at the controlled temperature of 23°±2°C, with successful metamorphosis for the first time. The artificial medium contained a mixture of M199, common carp plasma, and antibiotics/antimycotics. Glochidia were reared to the juvenile stage in the medium after 10–11 d of culture. After 15 d of controlled feeding with phytoplankton, the juveniles showed an elongated shell with several growth lines. Larval survival was 34.3±9.3%, whereas the proportion undergoing metamorphosis was ≤60.8±4.2%. The ultrastructure of early developmental stages was observed by scanning electron microscopy, from the glochidial to the juvenile stage. Glochidia had a hooked shell, with two equal triangular valves formed by a calcareous layer with numerous pores and covered by a thin cuticle of chitin–keratin. The appearance of the complete foot within 11 d of in vitro culture was considered the final feature of metamorphosis to the juvenile stage. The main alteration during juvenile development was the formation, under the glochidial shell, of a new periostracum with growth lines. The prominent foot, gradually covered by long, dense cilia, showed rhythmical movements involved in the capture of particulate matter. Similarly, cilia and microvilli present in the mantle also performed the same role. Longer cilia, sparsely distributed in the mantle, may function as chemotactile sensors.
Document Type: Research Article
Affiliations: 1: Instituto de Ciências Biomédicas de Abel Salazar, Departamento de Produção Aquática, Universidade do Porto, Porto 4099-003, Portugal 2: Department of Zoology, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand 3: Department of Agriculture, Faculty of Science and Technology, Rajabhat Bansomdejchaopraya University, Bangkok 10600, Thailand
Publication date: April 1, 2006