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MICROSPECTROPHOTOMETRIC ANALYSIS OF MITOSIS AND DNA SNYTHESIS ASSOCIATED WITH COLONY FORMATION IN PEDIASTRUM BORYANUM (CHLOROPHYCEAE) 1
Author(s) -
Millington William F.,
Rasch Ellen M.
Publication year - 1980
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.1980.tb03015.x
Subject(s) - biology , zoospore , pyrenoid , mitosis , feulgen stain , prophase , nuclear dna , dna synthesis , dna , cell division , botany , multinucleate , chlorophyceae , genome size , microbiology and biotechnology , spore , cell , algae , genetics , genome , chloroplast , meiosis , chlorophyta , mitochondrial dna , gene
Patterns of DNA synthesis and mitosis in the coenobial alga Pediastrum boryanum (Turp.) Meneghini were analyzed by cytophotometric measurements of individual, Feulgen‐stained nuclei from swarming zoospores aggregating into colonies, and cells in colonies varying in age from 12 to 96 h after their initial transfer to fresh culture medium. A haploid genome size of 0.2 pg DNA (corresponding to roughly 11 × 10 12 daltons, or 1.64 × 10 5 kb) was estimated by comparative measurements of nuclei from zoospores or young colonies and chicken erythrocyte (RBC) nuclei which were included with each set of Pediastrum slides as an internal reference standard of 2.5 pg DNA/cell. Although nuclear morphology and extent of chromatin condensation vary with different stages of colony development, nuclear division in P. boryanum appears to follow each cycle of DNA replication with no accumulation of DNA beyond the 2C level. Cytoplasmic cleavage resulting in the formation of individual zoospores is delayed until completion of mitosis, as is the demise of the pyrenoid. After 96 h of culture, 40% of all colonies have cells that are 8‐ or 16‐nucleate and some colonies have 32 nuclei/cell. Release of zoospores within vesicles occurs at this time to complete a cycle of asexual reproduction.