4 research outputs found
Explorations, Vol. 4, No. 2
Articles include:
Cover: Maya—painted clay figure from Jaina Island, Campeche, Mexico, 500-700A. D., approximately 100 percent. The clay figure is from a superb assemblage of pre-Hispanic materials from Mexico and Central America donated to the University of Maine’s Hudson Museum from the estate of William P Palmer III. In addition to this fine collection, Palmer donated an extensive array of objects from the Northwest Coast. Palmer earned his undergraduate degree in history and government from the University of Maine, and remained a strong, active supporter of the institution throughout his lifetime. More examples of objects from the Palmer Collection, including some pre-Columbian goldwork from Central America, may be found on page 10.
Editorial Reflections, by Carole J. Bombard
A Living Educational Experience: The Hudson Museum, by Richard G. Emerick
Molly in the Museum
Other Wonders, Other Ways
From Classroom Walls to High Tech Museum
Sharing Our Strengths: the development of youth conservation clubs in Pakistan, by James A. Sherburne
Up Close and Personal
Objects, Signs, and Symbols from Scafell to Chamonix: Visions of Mont Blanc, by Robert Brinkley
Public Service in Special Places: Music Education as Empowerment, by Susan Grindel Cosset Lambs, Floods and Stars, by Roberta Chester
Tuning the Immune System Fighting AIDS, Cancer and Other Diseases, by Anne P. Sherblom and Charles E. Moody
Why do they do it? One Graduate Student Explains, by Diane Carroll
Nutrition and Reproduction in Cows, by Barbara Barton and Diane Carroll
Diane Carroll: former graduate student Research News
Research New
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Shedding of the major plasma membrane sialoglycoprotein from the surface of 13762 rat ascites mammary adenocarcinoma cells
ASGP-1 (ascites Sialoglycoprotein 1) the major sialoglycoprotein of 13762 rat ascites mammary adenocarcinoma cells, is shed from MAT-B1 (nonxenotransplantable) and MAT-C1 (xenotransplantable) sublines when incubated
in vitro after labeling
in vivo with [
3H]glucosamine. The rates of shedding of label in both particulate and soluble form are similar for the two sublines, but the turnover of label in the cells is 80% greater for MAT-C1 cells (
t
1
2
2.4 days) than for MAT-B1 cells (
t
1
2
4.1 days). Shed soluble ASGP-1 was smaller than ASGP-1 in the particulate fraction by gel filtration in dodecyl sulfate. By CsCl density gradient centrifugation, gel filtration, and sucrose density gradient centrifugation, all in 4
m guanidine hydrochloride, the shed soluble ASGP-1 was found to be slightly more dense and smaller than ASGP-1 purified from membranes. No differences in sialic acid or oligosaccharides released by alkaline borohydride treatment were found between the shed soluble ASGP-1 and purified ASGP-1. These results suggest that the shed soluble ASGP-1 is released from the membrane by a proteolytic cleavage. This mechanism is supported by the inhibition of the release of soluble shed ASGP-1 by aprotinin, a protease inhibitor. Soluble ASGP-1 in ascites fluid is also smaller by gel filtration, but is more heterogeneous, suggesting a similar release mechanism
in vivo followed by more extensive degradation in the ascites fluid
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Changes in expression of a major sialoglycoprotein associated with ascites forms of a mammary adenocarcinoma
Glycoproteins of a cultured form (MR) of the 13762 rat mammary adenocarcinoma and its variants have been studied by analyses for peanut agglutinin receptors, [
3H]glucosamine labeling, lactoperoxidase labeling and CsCl density gradient centrifugation. The 13762 MR cells, derived from 13762 MAT-B ascites cells, do not contain detectable ASGP-1, the predominant cell surface sialoglycoprotein of the ascites forms of the 13762 tumor.
Transplantation and continued passage as ascites cells of MR cells or clonal lines derived from MR results in abrupt expression of ASGP-1 at about passage 16; it is absent in early passages of the ascites tumor. When these ascites cells are transferred to culture, ASGP-1 is again lost. No ASGP-1 is found in solid tumors derived from subcutaneous transplantation of the 13762 MR cells. The results suggest modulation of ASGP-1 content of the 13762 tumor cells