Programmed Cell Death in Dinoflagellates

Segovia, Marı́a

doi:10.1007/978-0-387-76717-8_11

Cited by 12 publications

(12 citation statements)

References 96 publications

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“…The chromosomal structure of dinoflagellates is also unique as they possess a special form of nucleus in which the chromosomes are almost permanently condensed throughout the cell cycle (reviewed by Segovia, 2008). The type of cell death occurring in dinoflagellates and other microalgae is thought to be species-specific and/or to be dependent on a triggering factor (Segovia, 2008;Jiménez et al, 2009) not previously been observed in our laboratory nor reported in the literature. These cyst-like structures are similar to asexual temporary or ecdysal cysts documented previously for other dinoflagellates under stress conditions (Blanco, 1995), such as cold temperatures (Hardeland, 1994).…”

Section: Discussionmentioning

confidence: 87%

“…Bidle and Bender (2008) reported an increase in caspase-like activities in an aging culture of the diatom Thalassiosira pseudonana while the occurrence of PCD, with the participation of cysteine proteases, was similarly proposed to explain the sudden termination of a bloom of the freshwater dinoflagellate Peridinium gatunense (Vardi et al, 1999). Because the type of cell death in microalgae can be species-specific and influenced by a triggering factor, it is challenging to identify a F o r P e e r R e v i e w 15 process common to diverse species of microalgae (Segovia 2008;Jiménez et al, 2009;Affenzeller et al, 2009). In cells of the green alga Micraterias denticulate, the occurrence of PCD, associated with an increase in caspase-like activity, has been observed when cells were exposed to H 2 O 2 (Darehshouri et al, 2008) while a caspase-like independent PCD was reported for the same species upon exposure to salt stress (Affenzeller et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

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Temporal variation of caspase 3-like protein activity in cultures of the harmful dinoflagellates Karenia brevis and Karenia mikimotoi

Bouchard

Purdie

2010

Journal of Plankton Research

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Section: Discussionmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Temporal variation of caspase 3-like protein activity in cultures of the harmful dinoflagellates Karenia brevis and Karenia mikimotoi

Bouchard

Purdie

2010

Journal of Plankton Research

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“…These observations imply that apoptosis in polyp bail-out is probably disentangled from coral TNF signals. Considering the ancient origin of core apoptotic mechanisms and the growing number of reports on inter-kingdom communication between microbes and their eukaryotic hosts (Hughes and Sperandio 2008;Segovia 2008;Pacheco and Sperandio 2009), we hypothesize that the triggering signal of apoptosis in polyp bail-out is derived from microorganisms associated with corals (Fig. 5).…”

Section: Tnf Signaling Leads To Apoptosis and Coenosarc Degradationmentioning

confidence: 99%

Signaling pathways in the coral polyp bail-out response

Chuang

Mitarai

2020

Coral Reefs

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Polyp bail-out is a stress response exhibited by some pocilloporid corals, with mechanisms and consequences distinct from those of bleaching. Although induction of polyp bail-out has been demonstrated in the laboratory, molecular mechanisms underlying this response have rarely been discussed. We conducted genetic analyses of Pocillopora acuta during initiation of hyperosmosisinduced polyp bail-out, using both transcriptomic and qPCR techniques. Beyond upregulation of apoptosis and proteolysis, corals showed significant activation of tumor necrosis factor and fibroblast growth factor (FGF) signaling pathways during induction of polyp bail-out. In our qPCR analysis, a common upregulation profile, peaking at 43.0% salinity, was found in the FAS and CASP8 genes, whereas a different profile, showing significant upregulation up to 45.0%, was displayed by matrix metalloproteinases and genes in the FGF signaling pathway. These results suggest parallel involvement of an extrinsic apoptotic signaling pathway and FGF-mediated extracellular matrix degradation in polyp bail-out. Furthermore, in the XIAP, JNK, and NFKB1 genes, we detected a third expression profile showing linear upregulation that becomes maximal at the endpoint salinity level of the experiment (46.0%), indicating activation of anti-apoptotic and cell survival signals during polyp bail-out. Our results provide new insights into signaling pathways responsible for polyp bail-out and suggest the feasibility of inducing bail-out by specifically triggering these pathways without exerting lethal stresses on the corals, which in turn will facilitate acquisition of viable polyps for possible use in coral reef restoration.

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“…Among all the cell death classes, apoptosis has been mainly studied in metazoans, but vascular plants, as well as some unicellular eukaryotic organisms, show characteristic apoptotic-like features. Apoptosis-like phenomena occur in vascular plants ( Greenberg, 1996 ; Pennell and Lamb, 1997 ; Lam and del Pozo, 2000; Lam et al , 2001 ) and they have also been portrayed in unicellular organisms, including chlorophytes ( Berges and Falkowski, 1998 ; Segovia et al , 2003 ; Segovia and Berges, 2005 ), dinoflagellates ( Vardi et al , 1999 ; Dunn et al , 2004 ; Franklin and Berges, 2004 ; Segovia, 2007 ), diatoms ( Casotti et al , 2005 ), yeast ( Frohlich and Madeo, 2000 ), kinetoplastids and slime moulds ( Cornillon et al , 1994 ), and bacteria ( Lewis, 2000 ), including cyanobacteria ( Berman-Frank et al , 2004 ). Berges and Falkowski (1998) described a form of autocatalysed cell death in the single cell algae D. tertiolecta .…”

Section: Introductionmentioning

confidence: 99%

Different ways to die: cell death modes of the unicellular chlorophyte Dunaliella viridis exposed to various environmental stresses are mediated by the caspase-like activity DEVDase

Jiménez¹,

Capasso²,

Edelstein³

et al. 2009

Journal of Experimental Botany

111

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Programmed cell death is necessary for homeostasis in multicellular organisms and it is also widely recognized to occur in unicellular organisms. However, the mechanisms through which it occurs in unicells, and the enzymes involved within the final response is still the subject of heated debate. It is shown here that exposure of the unicellular microalga Dunaliella viridis to several environmental stresses, induced different cell death morphotypes, depending on the stimulus received. Senescent cells demonstrated classical and unambiguous apoptotic-like characteristics such as chromatin condensation, DNA fragmentation, intact organelles, and blebbing of the cell membrane. Acute heat shock caused general swelling and altered plasma membrane, but the presence of chromatin clusters and DNA strand breaks suggested a necrotic-like event. UV irradiated cells presented changes typical for necrosis, together with apoptotic characteristics resembling an intermediate cell-death phenotype termed aponecrosis-like. Cells subjected to hyperosmotic shock revealed chromatin spotting without DNA fragmentation, and extensive cytoplasmic swelling and vacuolization, comparable to a paraptotic-like cell death phenotype. Nitrogen-starved cells showed pyknosis, blebbing, and cytoplasmic consumption, indicating a similarity to autophagic/vacuolar-like cell death. The caspase-like activity DEVDase was measured by using the fluorescent substrate Ac-DEVD-AMC and antibodies against the human caspase-3 active enzyme cross-reacted with bands, the intensity of which paralleled the activity. All the environmental stresses tested produced a substantial increase in both DEVDase activity and protein levels. The irreversible caspase-3 inhibitor Z-DEVD-FMK completely inhibited the enzymatic activity whereas serine and aspartyl proteases inhibitors did not. These results show that cell death in D. viridis does not conform to a single pattern and that environmental stimuli may produce different types of cell death depending on the type and intensity of the stimulus, all of which help to understand the cell death-dependent and cell death-independent functions of caspase-like proteins. Hence, these data support the theory that alternative, non-apoptotic programmed cell death (PCDs), exist either in parallel or in an independent manner with apoptosis and were already present in single-celled organisms that evolved some 1.2-1.6 billion years ago.

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Programmed Cell Death in Dinoflagellates

Cited by 12 publications

References 96 publications

Temporal variation of caspase 3-like protein activity in cultures of the harmful dinoflagellates Karenia brevis and Karenia mikimotoi

Temporal variation of caspase 3-like protein activity in cultures of the harmful dinoflagellates Karenia brevis and Karenia mikimotoi

Signaling pathways in the coral polyp bail-out response

Different ways to die: cell death modes of the unicellular chlorophyte Dunaliella viridis exposed to various environmental stresses are mediated by the caspase-like activity DEVDase

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