Cell Death in Cyanobacteria: Current Understanding and Recommendations for a Consensus on Its Nomenclature

Abstract

Cyanobacteria are globally widespread photosynthetic prokaryotes and are major contributors to global biogeochemical cycles. One of the most critical processes determining cyanobacterial eco-physiology is cellular death. Evidence supports the existence of controlled cellular demise in cyanobacteria, and various forms of cell death have been described as a response to biotic and abiotic stresses. However, cell death research in this phylogenetic group is a relatively young field and understanding of the underlying mechanisms and molecular machinery underpinning this fundamental process remains largely elusive. Furthermore, no systematic classification of modes of cell death has yet been established for cyanobacteria. In this work, we analyzed the state of knowledge in the field of cyanobacterial cell death. Based on that, we propose unified criterion for the definition of accidental, regulated, and programmed forms of cell death in cyanobacteria based on molecular, biochemical, and morphologic aspects following the directions of the Nomenclature Committee on Cell Death (NCCD). With this, we aim to provide a guide to standardize the nomenclature related to this topic in a precise and consistent manner, which will facilitate further ecological, evolutionary, and applied research in the field of cyanobacterial cell death.

The Red Harmful Plague in Times of Climate Change: Blooms of the Cyanobacterium Planktothrix rubescens Triggered by Stratification Dynamics and Irradiance

“…It could further indicate a response to environmental stress endured during winter deep mixing. There is increasing knowledge that various cyanobacterial species can undergo programmed cell death triggered by a variety of abiotic stressors (see summary in Aguilera et al, 2021 ).…”

Disentangling top-down drivers of mortality underlying diel population dynamics ofProchlorococcusin the North Pacific Subtropical Gyre

“…The finding that model-data fits impute other sources of mortality as quantitatively significant suggests that we may be missing important feedback mechanisms in our representation of marine surface community dynamics. Indeed, phytoplankton loss from the surface oceans is likely to include factors beyond grazing and viral-induced lysis [74, 75]. In Box 1 we review some potential mechanisms that may contribute to the unaccounted losses of Prochlorococcus , including ecological feedback that leads to distinct functional and/or light-driven responses, aggregation and/or sinking, stress, population heterogeneity, as well as the possibility of having missed other sources of top-down mortality (e.g., uncharacterised viral infections or grazing by larger organisms).…”

A Stochastic Characterization of Hydrogen Peroxide-Induced Regulated Cell Death in Microcystis aeruginosa

“…The concentrations used in the present work were not intended for environmental applications such as cyanobacterial bloom control but to determine the range within which RCD most probably occurs. Nevertheless, the still limited number of field studies examining cell death in either marine or freshwater systems severely limits the understanding of the environmental conditions that elicit RCD in cyanobacteria ( Aguilera et al, 2021 ).…”

“…The concentrations used in the present work were not intended for environmental applications such as cyanobacterial bloom control but to determine the range within which RCD most probably occurs. Nevertheless, the still limited number of field studies examining cell death in either marine or freshwater systems severely limits the understanding of the environmental conditions that elicit RCD in cyanobacteria (Aguilera et al, 2021). The activation of cell death pathways in response to stressors like HP is considered RCD, regardless the particular genetic program actually involved and the morphological and biochemical features observed (Galluzzi et al, 2018).…”

“…It is important to emphasize that this terminology follows the conceptual framework and recommendations of the nomenclature committee on cell death (NCCD) ( Galluzzi et al, 2018 ). A similar approach has been recently introduced for studies on cell death in cyanobacteria, including recommendations to characterize of RCD pathways by combining molecular, biochemical, and morphologic aspects following the directions of the (NCCD) ( Aguilera et al, 2021 ). Therefore, we will hereon refer to RCD in all cases where a stressor triggers an active form of cell death regardless the specific cellular pathway involved (i.e., ferroptosis, pyroptosis, apoptosis, necroptosis, etc.)…”