Date of Award

1-1-1995

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Abstract

To determine the suitability of juvenile paddlefish (Polyodon spathula) as experimental animals, fish were maintained for 154 d in a 378-L aquarium with distilled, deionized water in a flow-through system with a low inflow rate. Un-ionized ammonia levels were higher (median of 7-d mean values = 0.66 mg/L) than is considered optimal for warmwater fish. Weight gain varied from 0.05 to 0.33 g/d. Juvenile paddlefish were fully anesthetized in 4-6 min with tricane at a concentration of 66.1 mg/L. Blood collection was safer and more efficient when the caudal vessels were used rather than cardiac puncture.Sera, macrophages and alimentary canals containing Hysterothylacium dollfusi (Nematoda: Anisakidae) were obtained from paddlefish taken from the upper Missouri River drainage during spring spawning migrations.Alimentary canals of paddlefish (n = 27) were examined for helminths and H. dollfusi were morphometrically analyzed to relate larval and adult forms. Morphometric values for encysted (third-stage larvae) and lumenal (fourth-stage larvae and adults) forms were confluent, as defined by overlapping range values, when examined in developmental sequence. These values clearly indicate that the larvae are H. dollfusi. Data on distribution of larval and adult forms of H. dollfusi showed that all developmental stages were significantly more abundant (P $<$ 0.025 to 0.001) in the anterior alimentary canal.Paddlefish sera and macrophages were used to examine possible interaction between cellular and humoral components of the immune system and encysting H. dollfusi larvae. Serum from male (n = 5 of 9) and female (n = 3 of 44) paddlefish examined in double-immunodiffusion assays contained precipitating antibodies that reacted with homogenate prepared from H. dollfusi larvae. A significantly higher (P $<$ 0.005) percentage of male serum contained precipitating antibodies. Adherence assays showed that macrophages from paddlefish adhere to H. dollfusi larvae in vitro and that the time required for paddlefish macrophages to appear on the surface of larvae is significantly less (P $<$ 0.005) for antibody opsonized larvae compared to non-treated larvae. Observations also indicated that a heat-labile component of paddlefish serum may opsonize larvae for macrophage adherence.

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