AMESON MICHAELIS (MICROSPORIDA) IN THE BLUE CRAB, CALLINECTES SAPIDUS: PARASITE-INDUCED ALTERATIONS IN THE BIOCHEMICAL COMPOSITION OF HOST TISSUES

¹ Department of Zoology & Physiology, and Department of Biochemistry, Louisiana State University, Baton Rouge, Louisiana 70803

Ameson michaelis' interaction with its blue crab host significantly altered the biochemical constituents of host tissues. Modifications in skeletal muscle protein and carbohydrate metabolism were reflected in substantial variations in hemolymph composition. Blood osmolality, Cl^-, and Na⁺ ion levels decreased with heavy parasitic invasion, while K⁺ ion and ninhydrin positive substances (NPS) levels increased in both light and heavy infections. Microsporidiosis resulted in a general increase in all hemolymph free amino acids detected except glutamic acid.

Effects of A. michaelis sporogenesis were observed by comparing the biochemical composition of thoracic and cheliped skeletal musculature. Protein and carbohydrate levels were lower in infected thoracic muscle. The opposite trend was observed for tissue free-amino-acids (ninhydrin-positive substances). The concentration of nine of the sixteen amino acids detected remained unchanged with infection. Skeletal muscle glutamate, proline, glycine, alanine, and arginine levels declined, while taurine and tyrosine levels increased.

Lactic acid accumulated in the hemolymph, thoracic muscle, and hepatopancreas of parasitized blue crabs. Lactate concentrations reached six to seven times their normal levels in hemolymph and skeletal muscle, and four times the control value in the hepatopancreas. Blood glucose levels declined during the terminal stages of microsporidan infection.