Characterization of the Cyanobacteria Anabaena sp. PCC 7120 and iPC
Session Number
A05
Advisor(s)
Robert Haselkorn, University of Chicago Amin Nasser, University of Chicago
Location
B101
Start Date
28-4-2016 11:05 AM
End Date
28-4-2016 11:25 AM
Abstract
Cyanobacteria are gram-negative prokaryotes that perform oxygenic photosynthesis by fixing carbon dioxide to produce oxygen. Multiple species, such as Anabaena sp. PCC 7120, of cyanobacteria are also capable of fixing N2 when nitrogen sources in the environment are scarce. Around 10% of the vegetative cells of the filamentous cyanobacteria Anabaena sp. PCC 7120 differentiate into heterocysts, cells that specialize in fixing nitrogen, in response to lack of nitrogen sources. Phycobilisomes are protein complexes composed of phycobiliproteins that catch sunlight to use in oxygenic photosynthesis and exist within the thylakoid membranes of vegetative cells. The phycobiliproteins absorb light and are composed of an α and β subunit. We removed the α and β subunit of phycocyanin, one of the phycobilproteins, to create iPC, a mutated strain of Anabaena. The wild type is an unaltered sample of Anabaena and was used as a comparison against iPC. Cells of both were grown in medium with and without a nitrogen source in order to force heterocysts to form. We found differences in the growth pattern and the size of the phycobilisomes within the cells. We determined that the average distance between thylakoid membranes in thw wild type is 61.1nm (±11.7 SD) while the average distance in iPC was 37.1 nm (±9.7 SD). We also found that that the lack of phycobilisome in iPC had an effect on the growth of filaments.
Characterization of the Cyanobacteria Anabaena sp. PCC 7120 and iPC
B101
Cyanobacteria are gram-negative prokaryotes that perform oxygenic photosynthesis by fixing carbon dioxide to produce oxygen. Multiple species, such as Anabaena sp. PCC 7120, of cyanobacteria are also capable of fixing N2 when nitrogen sources in the environment are scarce. Around 10% of the vegetative cells of the filamentous cyanobacteria Anabaena sp. PCC 7120 differentiate into heterocysts, cells that specialize in fixing nitrogen, in response to lack of nitrogen sources. Phycobilisomes are protein complexes composed of phycobiliproteins that catch sunlight to use in oxygenic photosynthesis and exist within the thylakoid membranes of vegetative cells. The phycobiliproteins absorb light and are composed of an α and β subunit. We removed the α and β subunit of phycocyanin, one of the phycobilproteins, to create iPC, a mutated strain of Anabaena. The wild type is an unaltered sample of Anabaena and was used as a comparison against iPC. Cells of both were grown in medium with and without a nitrogen source in order to force heterocysts to form. We found differences in the growth pattern and the size of the phycobilisomes within the cells. We determined that the average distance between thylakoid membranes in thw wild type is 61.1nm (±11.7 SD) while the average distance in iPC was 37.1 nm (±9.7 SD). We also found that that the lack of phycobilisome in iPC had an effect on the growth of filaments.