The mechanism of cell binding and cell-sheet formation in L strain fibroblasts

L strain mouse fibroblasts grow as single, rounded, independent units in suspension cultures containing horse serum. Serum is apparently not essential as a growth factor, since analogous and sustained growth can be obtained when methyl cellulose is substituted for serum in suspension culture. In the absence of either serum or methyl cellulose, binding occurs between adjacent cells and in suspension cultures cell sheets form. In this situation there is little or no net synthesis of DNA, RNA or protein. The protein involved in cell sheet formation is present on the surface of the cells at all times even when they are growing as rounded units in suspensions containing horse serum or methyl cellulose, since elaboration of fibers by such cells can be observed in a very short interval when they are transferred to saline. Binding between cells is dependent upon pH and these studies suggest that the phenomenon is due to cross linkage by polyvalent cations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32409/1/0000486.pd

The plateau phase of growth of the L-M strain mouse cell in a protein-free medium : III. The effect of added glucose on protein and nucleic acid synthesis and on carborhydrate utilization

The addition of radioactive glucose to suspension cultures of L-M strain mouse cells during the plateau phase has been shown to extend the duration of this period from the normal 48-72 hr to 144-240 hr. Supplemental carbohydrate serves both as an energy source, as detected by the production of radioactive lactic acid and carbon dioxide, and as a precursor for nucleic acid and protein synthesis during this period. On the basis of the specific activities of the nucleic acids and proteins recovered from both the cells and the medium, possibilities of synthesis of multiple proteins and of extracellular RNA are discussed. The addition of radioactive homologous nucleic acidprotein fractions to culture in logarithmic growth is shown to reduce the mean generation time by 50 per cent. The recovery of 12 to 13 per cent of the radioactivity in these same fractions isolated from the cells at the end of logarithmic growth suggests that cells have the potential for re-utilization of cellular material release into the medium from other cells in the population.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32067/1/0000111.pd

Engagement of students in writing when using strategies from mentor authors

Plan B Paper. 2013. Master of Science in Education- Reading--University of Wisconsin-River Falls. Teacher Education Department. 27 leaves. Includes bibliographical references (leaves 26-27).Teachers are continually looking for ways to motivate their students to become more engaged while writing. This action research focused on the incorporation of mentor author(s) into a kindergarten classroom writer's workshop. The first study compared the volume and complexity of students' writing before and after the inclusion of a mentor author. The results of this study showed that the volume of students' writing increased, as well as complexity in terms of dialogue and more punctuation. The study also demonstrated an increase in students' time on task while writing after the use of mentor texts. The second study looked more in depth at the time spent on task writing while incorporating a mentor text into the writer's workshop mini lesson. The results of this study showed that students were more engaged in their writing after listening to a mentor text read aloud during the mini lesson at the beginning of the writer's workshop time