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ENHANCED GROWTH RATES OF THE GERMLINGS OF CYANOBACTERIAL RESTING SPORES (AKINETES)
Author(s) -
Jameson I.,
Thompson P.A.,
Blackburn S.
Publication year - 2000
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 - 10.1046/j.1529-8817.1999.00001-101.x
Subject(s) - biology , germination , spore , dormancy , population , growth rate , dominance (genetics) , botany , algae , nutrient , horticulture , zoology , ecology , demography , geometry , mathematics , sociology , gene , biochemistry
In experiments with the toxic cyanobacterium, Anabaena circinalis , we investigated the nature of cyst formation and germination under different environmental conditions (variation in light quality and quantity, temperature, nutrient limitation). We consistently found that germlings up to about 5 days old had greater growth rates than those of vegetative cells grown under similar saturating irradiance and excess nutrient conditions in batch culture. Averaging the results from 4 experiments, the specific growth rate (K′) fell from 1.9 d‐1, 24 hours after germination to 1.17, 1.04, 0.8, and to 0.45 d −1 after 48, 72, 120 and 144 hours, respectively. This equates to an increase in generation time from 0.37 to 1.54 days over this 6 day period. To investigate the implications of these results we modelled two hypothetical populations, A & B, with an initial akinete or resting cyst concentration of 10/mL each, but with population A having a standard growth rate of 0.45 and B with the 6 day early enhanced growth rate as determined in our laboratory experiments. The model indicates that population B quickly establishes dominance over population A. In this modeling exercise we have assumed a germination frequency of 100% for both populations but our laboratory results indicate that even given optimum germination conditions this factor may vary between 5% and 90% depending on the age of akinetes and the conditions experienced during dormancy (senescence). Some conditions that determine germination frequency were also investigated.