Document Type

Thesis - University Access Only

Award Date

1998

Degree Name

Master of Science (MS)

Department / School

Biology and Microbiology

Abstract

The strobilocercus stage of the cat tapeworm, Taenia taeniaeformis, is surrounded by a single syncytial sheet of cytoplasm, called the tegument. The outer cellular membrane of the tegument covers both the scolex/strobila (SIS) and the bladder portions of the strobilocercus, but only the SIS region is resistant to intestinal digestion. It has been suggested that the glycocalyx, the surface-exposed glycoconjugates of the outer membrane, may serve to insulate underlying surface membrane components from digestion. In Chapter I of this study, we used lectin binding to test the hypothesis that the glycocalyx of the SIS is different from that of the bladder and that this may serve as the resistance mechanism of the SIS to digestion. Biotin-labeled lectins with an avidin-glucose oxidase detection system were applied to whole strobilocerci and fluorescein isothiocyanate (FITC)-conjugated lectins were applied to 1 μm epon-araldite plastic sections of strobilocerci. Lectin-specific binding and distribution indicated the presence of some surface sugar components of the SIS region that were not present on the bladder. Lectins bound to either both regions of the strobilocerci, to the SIS regions only, or did not bind at all. The restriction of some glycoconjugates to the glycocalyx of the SIS is consistent with our hypothesis. The purpose of the experiments included in the second chapter of this thesis was to examine the differences between the glycoprotein components of the bladder membrane and those of the SIS. A technique for isolating the tegument from T. taeniaeformis strobilocerci using a 0.1 % digitonin solution has been described by Mills et al. (1984). As part of our objective, it was necessary to modify the Mills et al. (1984) technique slightly to isolate the tegument separately from each of the morphological regions of the strobilocerci. Our initial attempts to replicate the Mills et al. (1984) stripping experiment using intact strobilocerci resulted in collapsed bladders during the vortexing step. Therefore, attempts were made to use stripping conditions for the bladder that were less aggressive than for the strobila portions. For these studies, bladder and S/S portions were cut from the strobilocerci, and the pseudostrobila portions were discarded. For the remainder of the study, the bladder portions were incubated for 10 min and not vortexed. Scanning electron microscopy (SEM) and light microscopy of plastic sections were used to evaluate the degree of tegumental stripping achieved under each condition. The isolated tegumental membranes were separated by sodium dodecyl sulfate polyacrylamide electrophoresis (SDS-P AGE), and the proteins were visualized with Coomassie blue staining. Our results suggest that there are many shared proteins between the regions, with 26 major proteins present in the intact strobilocerci. Out of the total proteins, only two major bands were present in the separated bladder and strobili portions, but not in the intact strobilocerci. Surprisingly, even the isolated proteins from the bladder and strobila regions were very similar, sharing 22 out of 29 bands. To characterize the glycan portion of the glycoproteins in our study, the proteins were blotted onto polyvinylidene difluoride (PVDF) membranes and incubated with biotinylated lectins. Using Western blot analysis with lectins, we determined that the majority of the tegumental proteins were glycosylated to some degree. Some of the lectins bound to many of the tegumental proteins (e.g., concanavalin A), but others bound to very few proteins ( e.g., Ulex europaeus I). Of particular interest to our hypothesis was soybean agglutinin which bound to a 7. 5 kDa protein only from the SIS region, but not from the bladder region. The presence of glycosylated proteins unique to the S/S region is consistent with our hypothesis that complex sugars of the glycocalyx may be involved in the mechanisms of resistance to digestion, and these glycoproteins should be the focus of further studies of this mechanism.

Library of Congress Subject Headings

Taenia taeniaeformis Cats -- Parasites Glycoproteins

Format

application/pdf

Number of Pages

93

Publisher

South Dakota State University

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