Raphides in petioles of Xanthosoma sagittifolium are needlelike crystals about 50 micrometers long. The rectangular cross sections have maximum dimensions of approximately 850 by 250 nanometers. The raphides have two distinct end structures. One end is narrow, acute, and tapered to a point; the other is broad, acute, and abruptly pointed. Barbs, about 750 angstroms long with tips oriented away from the narrow end, occur along the length of the raphide on ridges on either side of two longitudinal grooves. These grooves, located opposite each other, give the raphide cross section an H-shape.
Abstract. Growth characteristics and nutrient changes in medium and cells of batchgrown sugarcane cultures were investigated over a period of 14 days. Amino acids, PO~-and K ÷ were substantially removed from the medium during the first seven days of culture; a strong preference for uptake of organic nitrogen over inorganic nitrogen was observed. Sodium uptake increased during the time when K + was becoming deficient in the medium. The main anions taken up were SOl-and PO]-. Strong acidification and a virtually total extraceilular hydrolysis of sucrose in the medium during the first seven days of culture were also observed.Tapering off of the rapid growth phase was accompanied by an increase of intracellular sucrose and a decrease of intracellular protein. As cells went from rapid growth into stationary phase, cytoplasmic space of the cells decreased slightly in favor of vacuolar space. Overall cell volume stayed constant throughout the growth cycle, except during a short period before onset of rapid growth.Transport of the glucose analog 3-O-methyl glucose remained constant in terms of K m value but the Vma x was slightly higher in rapidly growing ceils.
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