DOI: 10.5061/dryad.np5hqbzpk
title: Photoinhibition of photosystem II in Phytoplankton: Processes and patterns

description: All the diverse lineages of phytoplankters use conserved Photosystem II
 complexes to mediate photochemical extraction of electrons from water,
 with concomitant release of oxygen. Photosystem II suffers light-dependent
 photoinactivation through multiple mechanisms, which is in turn countered
 by protein subunit removal and replacement. This cycle imposes both direct
 costs and also delayed opportunity costs. The effective quantum yield for
 photoinactivation of Photosystem II depends upon taxa, cell size, prior
 acclimation state, the instantaneous spectral regime and light level. Low
 temperature or constraints upon metabolism can drive up excitation
 pressure and photoinactivation, while slowing counteracting repair.
 Environmental shifts in nutrients or CO2 alter resource allocations and
 electron flows, with sometimes counter-intuitive effects upon
 susceptibility to photoinactivation across taxa. These interacting factors
 generate a wide range of susceptibilities to photoinactivation across
 phytoplankton cells. Some phytoplankters engage in luxury or pre-emptive
 recycling of Photosystem II proteins before photoinactivation occurs, and
 some accumulate large pools of Photosystem II proteins outside active
 complexes, which may relate to the diverse thylakoid architectures across
 taxa. These interacting factors generate complex cost-benefit tradeoffs to
 maintain Photosystem II, and thus the range of conditions where oxygenic
 photosynthesis is feasible for a given taxa.
description: File: PhytoplanktonPhotoinactivationData<br>Types of data:
 Categorical and numeric data on environmental and growth conditions for
 the analyzed phytoplankton, and numeric data on parameters quantifying the
 photoinactivation and repair of Photosystem II across the analyzed
 phytoplankton. Data processing: Phytoplankton
 Photosystem II functional data was collated from the laboratory archives
 of D.A. Campbell and  J. Serôdio, and from published sources.
 Plots of Photosystem II function vs. time or vs. cumulative
 incident photons were used to extract parameters for Photosystem II
 photoinactivation, and for counteracting repair of Photosystem II. Fitting
 equations are described in the accompanying book chapter, and in
 <br>Campbell DA, Tyystjärvi E (2012) Parameterization of photosystem
 II photoinactivation and repair. Biochimica et Biophysica Acta (BBA) -
 Bioenergetics 1817:258–265. doi:
 10.1016/j.bbabio.2011.04.010<br><br>Data collation was
 performed under macOS 10.13.2 using Microsoft Excel for Mac 16.16.1. 
 Curve fitting was performed using R 3.5.0 running under RStudio 1.1.453,
 with non-linear least squares analyses through minpack.lm: R Interface to
 the Levenberg-Marquardt Nonlinear Least-Squares<br>Algorithm Found
 in MINPACK, Plus Support for Bounds, Timur V. Elzhov, Katharine M. Mullen,
 Andrej-Nikolai Spiess and Ben Bolker 2016, R package version 1.2-1,
 https://CRAN.R-project.org/package=minpack.lm.
description: Missing data cells left blank for compatibility with import into
 R.<br><br>Additional data from the Campbell lab archives
 available through:<br>phytoplankton.mta.ca List
 of column heading (variable) definitions  in accompanying
 'PhytoplanktonPhotoinactivationDataDefinitions.csv'.