Spindle-severing experiments

Spindle-severing experiments in wild- type embryos... 

We conducted spindle-severing experiments in the wild-type one-cell stage C. elegans embryo to investigate whether extra-spindle pulling forces participate... 

We conducted spindle-severing experiments in par-2 and par-3 mutant embryos to test the validity of this model. In wild type, PAR-3 protein is restricted to the anterior cortex and PAR-2 protein to the posterior cortex (Boyd et al 1996, Etemad-Moghadam et al 1995). In par-2 mutants, PAR-3 expands to fill the... 

This work was funded by the R D organization at Owens-Illinois, Inc. Kathryn Perkins, Faith Workman, and Brett Hixson assisted in sample preparation and with several experiments. Daniel Ragland helped with the FTIR experiments. Carl Fayerweather provided support for the rotating spindle viscometer experiments. Richard Sipes help with UV-Vis experiments is greatly appreciated. Discussions with the 0-I s Glass Science Discipline members, both past and present, were helpful in the development of this project and in the preparation of this document. Comments fi-om several members of O-I R D, particularly Scott Weil, William Pine, Carol Click, and Ludovic Valette, improved the quality of this document and are greatly appreciated. 

Spindle Elongation in Anaphase B Findings from several types of experiments have Implicated three processes in the separation of the poles In anaphase B a pushing force gen-... 

Several lines of evidence indicate that MPF-catalyzed phosphorylation also plays a role in chromosome condensation and formation of the mitotic spindle apparatus. For instance, genetic experiments in the budding yeast S. cerevisiae identified a family of SMC (structural maintenance of chromosomes) proteins that are required for normal chromosome segregation. These large proteins (-1200 amino acids) contain characteristic ATPase domains at their C-termlnus and long regions predicted to participate in colled-coll structures. 

The relationships between mitotic mechanisms and certain very general problems in cell biology are now becoming clearer, if only in terms of the questions and not the answers. The major new area of contact is self-assembly, researches on assembly of viral and other proteins give a new view of many mitotic problems. In turn, given the in-vivo observations and experiments on mitosis available for correlation, future in-vitro studies of isolated chromosomes and spindle proteins promise a larger view of the functional role of reversible self-assembly. This and several other general problems may be clear from the earlier considerations, but a most basic one needs more explicit discussion. 

The experiments provided one more extremely valuable piece of information. None of the compositions analyzed allowed seizure of mating elements. This fact needs to be emphasized, as the conditions within a friction couple during such tests are extreme (rotational speed of the spindle 500 rpm, load increase 409 N/s, maximum loading of friction couple 8000 N). Many of the commonly used lubricants based on conventional bases and additives cannot withstand such severe experimental conditions [130]. A schematic of changes in friction torque for commercial products is shown in fig. 18.25. 

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