Absorption and photosynthetic action spectra

Article Abstract:

Optical absorption, excitation, fluorescence, and emission, and photosynthetic action spectra have been measured in vivo for intact colonies of the marine diazotrophic, that is, nitrogen-fixing, cyanobacteria Trichodesmium of the Caribbean Sea to look at the source of variability in fluorescence and absorption on Trichodesmium spp. Findings indicate that the phycourobilins (PUBs) and phycoerythrobilin (PEBs) in Trichodesmium act as a dynamic biophysical energy valve that modifies the rate of excitation energy delivered to photosystem II (PSII) as a response to changes in ambient light regime. A clear diel periodicity was found in the ratio of optical absorption cross-sections of PUB to PEB.

Caribbean Region, Biophysics, Caribbean Sea, Oceanographic research, Nitrogen-fixing microorganisms

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Relationship between microcystin production and cell division rates in nitrogen-limited Microcystis aeruginosa cultures

Article Abstract:

Cell growth changes, cell division rates, mycrocystin production rate, microcystin cell quota, and gravimetric microcystin concentration have been investigated in nitrogen-limited batch cultures of axenic and non-axenic strains of Microcystis aeruginosa. The coupling of cell division and microcystin production is discussed in relation to environmental factors.

Cell division

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Inorganic nitrogen acquisition in the seagrass Thalassia testudinum: development of a whole-plant nitrogen budget

Article Abstract:

Inorganic nitrogen (N) acquisition in the seagrass Thalassia testudinum is discussed relative to development of a whole-plant N budget by using whole-plant uptake experiments. Aquatic vascular plants can take up inorganic N through leaf and root tissues both, and it was found that they contributed equally to the T. testudinum N budget.

Statistical Data Included, Seagrasses

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