Alterations in the biochemistry and ultrastructure of the deep abdominal flexor muscle of the Norway lobster Nephrops norvegicus during infection by a parasitic dinoflagellate of the genus Hematodinium

Changes in various biochemical and ultrastructural characteristics of the deep abdominal flexor (DAF) muscles were studied in Norway lobster Nephrops norvegicus (L.) from the Clyde estuary, Scotland, UK, at different stages of infection by a parasitic dinoflagellate of the genus Hematodinium. Abdominal DAF muscles from infected lobsters showed slight, significant increases in total water content, along with greatly depleted glycogen reserves and an altered free amino acid profile. However, protein concentration and composition remained unchanged. Ultrastructurally, parasitic infection of DAF muscle fibres caused alterations in sarcolemmal structure, and localized disruption of myofibrillar bundles around the periphery, but not throughout the centre of the fibres. Overall, the reduction in swimming performance previously reported for N. norvegicus during Nematodinium infection reflect an alteration in carbohydrate supply to the active muscle and some subtle disruption of muscle structure. The altered carbohydrate titre could reflect the Hematodinium parasites acting as a carbohydrate sink in the haemolymph, a disruption of normal tissue glycogenesis, or some alteration in the host's hormonal regulation. These changes could also adversely affect the taste, texture and marketability of infected meat.