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Full-Text Articles in Physical Sciences and Mathematics
Do Prokaryotes Contain Microtubules?, Lynn Margulis, D. Bermudes, G. Hinkle
Do Prokaryotes Contain Microtubules?, Lynn Margulis, D. Bermudes, G. Hinkle
Lynn Margulis (1938 - 2011)
In eukaryotic cells, microtubules are 24-nm-diameter tubular structures composed of a class of conserved proteins called tubulin. They are involved in numerous cell functions including ciliary motility, nerve cell elongation, pigment migration, centrosome formation, and chromosome movement. Although cytoplasmic tubules and fibers have been observed in bacteria, some with diameters similar to those of eukaryotes, no homologies to eukaryotic microtubules have been established. Certain groups of bacteria including azotobacters, cyanobacteria, enteric bacteria, and spirochetes have been frequently observed to possess microtubule-like structures, and others, including archaebacteria, have been shown to be sensitive to drugs that inhibit the polymerization of microtubules. …
A Computer-Based Atlas Of Global Instrumental Climate Data, Raymond S. Bradley, Linda G. Ahem, Frank T. Keimig
A Computer-Based Atlas Of Global Instrumental Climate Data, Raymond S. Bradley, Linda G. Ahem, Frank T. Keimig
Raymond S Bradley
Color-shaded and contoured images of global gridded instrumental data have been produced as a computer-based atlas, available to the climate community through Internet. Each image simultaneously depicts anomaly maps of surface temperature, sea level pressure, 500- mb geopotential heights, and percentages of reference period precipitation. Monthly, seasonal, and annual composites are available, in either cylindrical equidistant or Northern and Southern Hemisphere polar projections. Temperature maps are available from 1854 to 1991, precipitation maps from 1851 to 1989, sea level pressure maps from 1899 to 1991, and 500-mb height maps from 1946 to 1991. All images exist as GIP (Graphics Interchange …