Crystalloids in apparent autophagic plastids: Remnants of plastids or peroxisomes?

Papini, Alessio; Doorn, Wouter G. van

doi:10.1016/j.jplph.2014.10.010

Cited by 5 publications

(3 citation statements)

References 24 publications

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“…Autophagic activity in plastids has also been confirmed by cytochemical staining conducted on petals cells in Dendrobium flowers (van Doorn et al 2011). In addition, observations of crystalloids made by transmission electron microscopy show some evidence to support the hypothesis that autophagic plastids can degrade other plastids (Papini and van Doorn 2015). Plastids observed during the present study probably engulf portions of the cytoplasm.…”

Section: Discussionmentioning

confidence: 71%

“…In members of Crassulaceae, the presence of plastolysomes has not been described previously (Kozieradzka-Kiszkurno and Płachno 2013). However, it is important to note that the role of plastids as an autophagosome or autolysosome is not fully documented (Papini and van Doorn 2015). In S. sediforme , together with the plastids which are described above, autophagic vacuoles have been recorded during megasporogenesis (in cytoplasm of MMC, both cells of dyad, functional megaspore and other cells of triad) and megagametogenesis (coenocytic and cellular gametophyte).…”

Section: Discussionmentioning

confidence: 99%

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Female gametophyte development in Sedum sediforme (Jacq.) Pau (Crassulaceae): an anatomical, cytochemical and ultrastructural analysis

Brzezicka

Kozieradzka-Kiszkurno

2018

Protoplasma

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Available documentation about the development of the female gametophyte of Crassulaceae is very limited. The aim of this study was to extend the embryological knowledge of Crassulaceae by analysing the development of the embryo sac in Sedum sediforme . Transmission electron microscopy and light microscopy including Nomarski optics (DIC) were used to observe individual stages of female gametophyte development. Cytochemical staining enabled detection of lipids, insoluble polysaccharides and proteins in gametophyte cells during their formation. Their increased accumulation was observed during nucellar cell and unfunctional cell degeneration in the embryo sac at the coenocytic and cellular stages (megagametogenesis). The female gametophyte develops in anatropous, bitegmic and crassinucellate ovules. The mature embryo sac is built of seven cells but after antipodes degeneration it is formed by the egg apparatus and a central cell. The monosporic Polygonum type was observed. One megaspore mother cell (MMC) formed three cells after meiosis. A triad was formed from a functional megaspore (placed chalazally), one uninucleate megaspore and a binucleate cell located at the micropylar end. Plasmodesmata with adhering electron-dense dome were noticed in walls of the coenocytic embryo sac and in the outer walls of ephemeral antipodes. Moreover, similar to synergids, antipodes form wall ingrowths. Here, we report new structural features of the antipodal cells (the presence of plasmodesmata with an electron-dense dome) which have not been described before. This new structural observation indicates that these cells participate in substance transport and that this process can probably be additionally regulated.

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Section: Discussionmentioning

confidence: 71%

Section: Discussionmentioning

confidence: 99%

Female gametophyte development in Sedum sediforme (Jacq.) Pau (Crassulaceae): an anatomical, cytochemical and ultrastructural analysis

Brzezicka

Kozieradzka-Kiszkurno

2018

Protoplasma

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“…The mechanism of recovery of the thylakoid membrane components passes through the formation of a ring of membranes within the chloroplast that later fuses to multilamellar bodies. The presence of thylakoids in the vacuoles indicates that autophagy is involved in chloroplast component recycling, as already suggested by Dong et al (2013) for N. oceanica and, more in general, by Papini et al (2014) and Papini and van Doorn (2015). The mechanism of vacuole formation is apparently related to the dilation of ER elements that is considered one of the main ways of formation of autophagic vacuoles (Papini et al 2014).…”

Section: Discussionmentioning

confidence: 67%

Cell wall and organelle modifications during nitrogen starvation in Nannochloropsis oceanica F&M-M24

Roncaglia

Papini

Zittelli³

et al. 2021

J Appl Phycol

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Nannochloropsis oceanica F&M-M24 is able to increase its lipid content during nitrogen starvation to more than 50% of the total biomass. We investigated the ultrastructural changes and the variation in the content of main cell biomolecules that accompany the final phase of lipid accumulation. Nitrogen starvation induced a first phase of thylakoid disruption followed by chloroplast macroautophagy and formation of lipid droplets. During this phase, the total amount of proteins decreased by one-third, while carbohydrates decreased by 12–13%, suggesting that lipid droplets were formed by remodelling of chloroplast membranes and synthesis of fatty acids from carbohydrates and amino acids. The change in mitochondrial ultrastructure suggests also that these organelles were involved in the process. The cell wall increased its thickness and changed its structure during starvation, indicating that a disruption process could be partially affected by the increase in wall thickness for biomolecules recovery from starved cells. The wall thickness in strain F&M-M24 was much lower than that observed in other strains of N. oceanica, showing a possible advantage of this strain for the purpose of biomolecules extraction. The modifications following starvation were interpreted as a response to reduction of availability of a key nutrient (nitrogen). The result is a prolonged survival in quiescence until an improvement of the environmental conditions (nutrient availability) allows the rebuilding of the photosynthetic apparatus and the full recovery of cell functions.

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Investigation of Morphological Features of Autophagy During Plant Programmed Cell Death

Papini

2018

Methods in Molecular Biology

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The investigation of autophagy particularly when observed during programmed cell death (PCD) is strongly based on the morphological features recorded with transmission electron microscope (TEM). Here we describe methods to induce and to inhibit autophagy in plants. Also some tips for obtaining better preservation of biological membranes, crucial for the investigation of autophagy, are provided together with information about plant autophagic mutants, use of antibodies and methods for 3D reconstruction of large membrane-bound objects that are commonly formed during autophagic processes leading to PCD in plants.

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Crystalloids in apparent autophagic plastids: Remnants of plastids or peroxisomes?

Cited by 5 publications

References 24 publications

Female gametophyte development in Sedum sediforme (Jacq.) Pau (Crassulaceae): an anatomical, cytochemical and ultrastructural analysis

Female gametophyte development in Sedum sediforme (Jacq.) Pau (Crassulaceae): an anatomical, cytochemical and ultrastructural analysis

Cell wall and organelle modifications during nitrogen starvation in Nannochloropsis oceanica F&M-M24

Investigation of Morphological Features of Autophagy During Plant Programmed Cell Death

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