Tip-Growing Cells of the Moss Ceratodon purpureus Are Gravitropic in High-Density Media1

AUTOR(ES)

Schwuchow, Jochen Michael

FONTE

American Society of Plant Biologists

RESUMO

Gravity sensing in plants and algae is hypothesized to rely upon either the mass of the entire cell or that of sedimenting organelles (statoliths). Protonemata of the moss Ceratodon purpureus show upward gravitropism and contain amyloplasts that sediment. If moss sensing were whole-cell based, then media denser than the cell should prevent gravitropism or reverse its direction. Cells that were inverted or reoriented to the horizontal displayed distinct negative gravitropism in solutions of iodixanol with densities of 1.052 to 1.320 as well as in bovine serum albumin solutions with densities of 1.037 to 1.184 g cm−3. Studies using tagged molecules of different sizes and calculations of diffusion times suggest that both types of media penetrate through the apical cell wall. Estimates of the density of the apical cell range from 1.004 to 1.085. Because protonemata grow upward when the cells have a density that is lower than the surrounding medium, gravitropic sensing probably utilizes an intracellular mass in moss protonemata. These data provide additional support for the idea that sedimenting amyloplasts function as statoliths in gravitropism.

Documentos Relacionados

• Amyloplasts That Sediment in Protonemata of the Moss Ceratodon purpureus Are Nonrandomly Distributed in Microgravity1
• Transcription Profiling of the Early Gravitropic Response in Arabidopsis Using High-Density Oligonucleotide Probe Microarrays1[w]
• Association of Spectrin-Like Proteins with the Actin-Organized Aggregate of Endoplasmic Reticulum in the Spitzenkörper of Gravitropically Tip-Growing Plant Cells1
• Curvature Induced by Amyloplast Magnetophoresis in Protonemata of the Moss Ceratodon purpureus1
• Imaging and manipulation of high-density lipoproteins.