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Physiological and biochemical attributes of the host-parasite interface of Leptorhynchoides thecatus (Acanthocephala) in green sunfish (Lepomis cyanellus) relating to microhabitat specificity
Abstract
Preferential site selection of helminths within the alimentary canal of their vertebrate definitive hosts is a well documented phenomenon; however, the physiological basis of such microhabitat specificity remains enigmatic. Leptorhynchoides thecatus (Acanthocephala) is found in pyloric ceca of green sunfish but is unable to survive in the anterior intestine. Ceca have been suggested to provide a nutrient sequestering region or sheltered region to helminths. Substantial amounts of material were found to enter and move sequentially through the ceca with no food remaining in the ceca subsequent to gastric evacuation; therefore, it appears that ceca do not serve as a nutrient sequestering region or sheltered region to helminths. Physiological comparison of ceca and proximal intestine revealed that cecal protein concentrations were significantly higher. The anterior intestine exhibited higher levels of proteolytic activity; however, ceca exhibited higher levels of aminopeptidase activity. Cecal pH was higher than intestinal. Ceca contained greater total amounts of materials and, therefore, greater total amounts of nutrients. A significant time X place interaction was detected for total free amino acids suggesting that cecal enzymatic activity was responsible for increased amounts of intestinal amino acids. The influence of these factors on microhabitat specificity exhibited by L. thecatus was investigated by comparing the normal spatial distribution of worms to that in fish in which cecal pH was reduced to levels normally found in the anterior intestine, intestinal protein concentration was raised to levels normally found in the ceca, and from which food had been withheld. Protein concentration, pH, and starvation did not effect spatial distribution of worms. Cecal worms exhibited higher levels and broader ranges of aminopeptidase activity than intestinal worms while inhabiting an environment of relatively high aminopeptidase activity. The complex environments occupied by intestinal helminths suggest that microhabitats are defined by long histories of concomitant physiological adaptations by the worms to specific habitats.
Subject Area
Anatomy & physiology|Animals|Zoology|Forestry
Recommended Citation
Richardson, Dennis James, "Physiological and biochemical attributes of the host-parasite interface of Leptorhynchoides thecatus (Acanthocephala) in green sunfish (Lepomis cyanellus) relating to microhabitat specificity" (1995). ETD collection for University of Nebraska-Lincoln. AAI9528830.
https://digitalcommons.unl.edu/dissertations/AAI9528830