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Browsing by Author "DeCourcy, Kristi R."

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    Isolation and characterization of cathepsin Z, a lysosomal cysteine proteinase
    DeCourcy, Kristi R. (Virginia Tech, 1995-05-05)
    Cathepsin Z is a cysteine proteinase found in lysosomes of human cells. It was detected in human cultured cell lines using the peptidyl diazomethane inhibitor Fmoc-Leu-Leu- [¹²⁵]Tyr-CHN₂. The labeling of cathepsin Z by the inhibitor was both time- and concentration-dependent, and the proteinase was found in all human cell lines examined. The characteristics of cathepsin Z were examined in U-937 cells, a human monocytic line. The labeling of cathepsin Z was blocked by pre-incubation of the cells either in non-iodinated inhibitor or in the epoxysuccinyl peptide inhibitor E-64d, a specific inhibitor of cysteine proteinases. Cathepsin Z was not immunoprecipitated by antisera specific for cathepsins B, L, or S. Cathepsin Z has been estimated to be at millimolar concentrations in lysosomes, suggesting that it is a major lysosomal proteinase. The molecular weight of cathepsin Z was calculated to be 22.4 kDa by SDS-PAGE and 45— 47 kDa by native PAGE and gel exclusion chromatography, indicating that it is dimeric. Cathepsin Z is susceptible to digestion by endoglycosidase H, and oligosaccharides comprise 3.1 kDa of the reduced molecular weight. The expression of cathepsin Z was not affected by differentiation of U-937 cells with phorbol ester, unlike the expression of cathepsins B and S. Undifferentiated U-937 cells express low levels of cathepsins B and S; after differentiation, expression of cathepsins B and S is greatly increased. Cathepsin Z was purified from U-937 cells by anion exchange chromatography (Mono Q), affinity chromatography (concanavalin A), and preparatory electrophoresis. N-terminal sequence analysis of both the purified protein and fragments of the protein from a V8 digest indicates that cathepsin Z is a member of the papain superfamily of cysteine proteinases.
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    Phage Hunters
    Fralin, Scott; Voshell, Stephanie; DeCourcy, Kristi R. (Virginia Tech, 2018-03-12)
    Exhibit featuring the work of undergraduate students in the Phage Hunters course (BIOL 1135, 1136) a two-semester lab course that gives students the opportunity to find a bacteriophage in local soil. During the first half of the course, they isolate and characterize their phage. They get to name their phage and enter the data they collected in an online database at the end of the semester. The students select the most unique and interesting phages to be sent for genome sequencing over Winter Break. During the second half of the course, the students study the phage genomes gene by gene and ultimately submit their annotations to GenBank. They get to compare and contrast their phage with previously annotated phage to learn about the functions of the genes. This exhibit highlights the steps of phage discovery and characterization lab by providing examples of data collected by students over three years. 2018/03/12 - 2018/07/30
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    Territorial displays of male Anolis carolinensis: an analysis and critique
    DeCourcy, Kristi R. (Virginia Tech, 1991-05-05)
    Anolis carolinensis was found to have three stereotyped and distinct territorial headbob patterns, referred to as Types A, B, and C. Each type had two variants, one in which the dewlap appeared mid-display and a second in which dewlap extension was absent. Use of these signals was examined in two contexts: a "male-alone” or advertisement context and a "male-male" or aggressive context. Context accounted for only minor amounts of the variability while display type explained the majority of unit variability. Display rate in advertisement was 0.3 displays/ min, half the displays were solitary, and half occurred in volleys of 2-6 displays. Dewlap extension accompanied 97% of the displays, and all three types of displays were used. Display rate was eightfold greater in male-male context, and the rate doubled again as males came within 20 cm of each other. At large separation distances (>60 cm), long volleys (4-9 displays) were common, Type C displays predominated, and dewlap extension accompanied 92% of the displays. At smaller separation distances (<20 cm), single displays predominated, volleys had fewer displays, displays were more evenly divided among the three types, and 93% of the displays had no dewlap extension.