Life Sciences Commons^™

The Lin-14 Locus Of Caenorhabditis Elegans Controls The Time Of Expression Of Specific Postembryonic Developmental Events, Victor R. Ambros, H. Robert Horvitz

Victor R. Ambros

The lin-14 locus of Caenorhabditis elegans plays an important role in specifying the normal timing and sequence of developmental events in the lateral hypodermal cell lineages. The results of gene dosage, complementation, and temperature-shift experiments indicate that the fates expressed by cells at successive stages of these cell lineages are specified by the level of lin-14 activity and that lin-14 acts at multiple times during development to control stage-specific choices of cell fate. Our observations suggest that during normal development a reduction in the level of lin-14 gene function causes the sequential expression of stage-specific cell fates.

Mcnamara 1987 Uiuc Phd Dissertation - Morphogenetic Movements Contributing To Cell Aggregation In Dictyostelium Discoideum Wild-Type And Streamer F Mutants, George Mcnamara

George McNamara

Fine Structure Of The Substantia Nigra Pars Lateralis In The Opossum, Terrence Paul Ma

Wayne State University Dissertations

The cytoarchitecture of the substantia nigra pars lateralis (SNl) of the opossum was examined by light and electron microscopic procedures. Nissl-stained, Golgi-impregnated, HRP-reacted and electron microscopic preparations were utilized in this study. SNl neurons were divided into three groups on the basis of cell size; small, medium-sized, and large neurons. Small cells had a nucleus with some clumped heterochromatin, a relatively organelle-free cytoplasm, and long, thin, sparcely branching dendrites. Electron microscopic examination of small cells confirmed the light microscopic observations. Medium-sized neurons possessed a relatively clear nucleus, clumps of Nissl substance, especially at a juxtanuclear position near the emergence of …

Short-Term Feedback Regulation Of Camp By Accelerated Degradation In Rat Tissues, Tom W. Gettys, Peter F. Blackmore, J. Bruce Redmon, Stephen J. Beebe, Jackie D. Corbin

Bioelectrics Publications

A recent study showed that cAMP analogs lowered cAMP levels in rat hepatocytes. The present work demonstrates that cAMP analogs also lowered cAMP in a rapid, concentration-dependent manner in heart and fat cells. In order to determine if the cAMP-dependent protein kinase mediated this effect, techniques were developed to assay the protein kinase activity ratio in hepatocytes treated with cAMP analogs. The activation of protein kinase and phosphorylase in hepatocytes by 8-pClΦS-cAMP (where 8-pClΦS- indicates 8-parachlorothiophenyl-) was concentration-dependent and occurred in parallel to proportionate decreases in cAMP. More than 20% of the cAMP binding sites on the protein kinase were …

Microsurgical Fertilization Of Mammalian Eggs: An Assessment Of Clinical Utilization, Susan E. Lanzendorf

Theses and Dissertations in Biomedical Sciences

Microsurgical fertilization is the technique in which a spermatozoon or sperm nucleus is injected into the cytoplasm of an egg. To establish a foundation for the use of microsurgical fertilization as a means of treating infertility, this study evaluated the procedure in hamster and human eggs. Hamster sperm nuclei were microinjected into hamster eggs to determine the rate of abnormal fertilization and to ultrastructurally assess cellular damage by transmission electron microscopy. Hamster eggs were also injected with human spermatozoa obtained from fertile and infertile men to evaluate the fertilizing potential of the sperm cells. In addition, human eggs donated by …