e-journal

Mastoparan-induced programmed cell death in the unicellular alga Chlamydomonas reinhardtii

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† Background and Aims:
Under stress-promoting conditions unicellular algae can undergo programmed cell death (PCD) but the mechanisms of algal cellular suicide are still poorly understood. In this work, the involvement of
caspase-like proteases, DNA cleavage and the morphological occurrence of cell death in wasp venom mastoparan
(MP)-treated Chlamydomonas reinhardtii were studied.

† Methods:
Algal cells were exposed to MP and cell death was analysed over time. Specific caspase inhibitors were employed to elucidate the possible role of caspase-like proteases. YVADase activity (presumably a vacuolar
processing enzyme) was assayed by using a fluorogenic caspase-1 substrate. DNA breakdown was evaluated by
DNA laddering and Comet analysis. Cellular morphology was examined by confocal laser scanning microscopy.

† Key Results:
MP-treated C. reinhardtii cells expressed several features of necrosis ( protoplast shrinkage) and vacuolar cell death (lytic vesicles, vacuolization, empty cell-walled corpse-containing remains of digested protoplast) sometimes within one single cell and in different individual cells. Nucleus compaction and DNA fragmentation were detected. YVADase activity was rapidly stimulated in response to MP but the early cell death was not inhibited by caspase inhibitors. At later time points, however, the caspase inhibitors were effective in cell-death suppression. Conditioned medium from MP-treated cells offered protection against MP-induced cell death.

†Conclusions:
In C. reinhardtii MP triggered PCD of atypical phenotype comprising features of vacuolar and necrotic cell deaths, reminiscent of the modality of hypersensitive response. It was assumed that depending on the physiological state and sensitivity of the cells to MP, the early cell-death phase might be not mediated by
caspase-like enzymes, whereas later cell death may involve caspase-like-dependent proteolysis. The findings substantiate the hypothesis that, depending on the mode of induction and sensitivity of the cells, algal PCD may take different forms and proceed through different pathways.

Key words: Caspase-like proteases, cell death phenotype, Chlamydomonas reinhardtii, DNA disintegration, mastoparan, programmed cell death, signalling, YVADase.

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Ketersediaan

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Informasi Detail

Judul Seri

Annals of Botany

No. Panggil

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Penerbit

Oxford : Oxford University Press on behalf of the Annals of Botany Company., 2013

Deskripsi Fisik

Annals of Botany 111: 191–205, 2013

Bahasa

English

ISBN/ISSN

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Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

111: 2013

Subjek

FISIOLOGI TANAMAN

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

Versi lain/terkait

Lampiran Berkas

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