Dlaskova 2013 Abstract MiP2013

From Bioblast
Dlasková A, Tauber J, Špaček T, Alán L, Ježek P (2013) Distribution of nucleoids of mitochondrial DNA. Mitochondr Physiol Network 18.08.

Link: MiP2013, Book of Abstracts Open Access

Dlaskova A, Tauber J, Spacek T, Alan L, Jezek P (2013)

Event: MiPNet18.08_MiP2013

Robustness of the mitochondrial (mt) genome is given by thousand to hundred thousand (e.g. in mammalian eggs) copies of double stranded circular mtDNA (~16.5 kD in humans) in a single cell, while mtDNA is organized in nucleoids containing accessory proteins and recruited proteins of the mt replication/transcription machinery. It has been disputed whether a single nucleoid contains just a single mtDNA molecule [1] or up to 6 mtDNA molecules on average. Also a uniform size of nucleoids was disputed. Since the mt network undergoes locally frequent fission (fragmentation) and fusion events, and when integrated over time, a highly interconnected mitochondrial reticulum is seen, and since upon certain insults and/or pathological states a fragmented network may appear all the time, mt nucleoid (re-)distribution is very important also related to mitophagy. Using conventional confocal microscopy [2], we found only two major morphological states: i) a tubular state of the mitochondrial network with equidistant nucleoid spacing, 1.10 ± 0.2 nucleoids per m, and ii) a fragmented state of solitary spheroid objects in which several nucleoids were clustered. We rarely observed singular mitochondrial fragments with a single nucleoid inside and very seldom observed empty fragments. Reintegration of fragments into the mitochondrial network re-established the tubular state with equidistant nucleoid spacing. The two major morphological states coexisted at intermediate stages. These observations suggest that both mitochondrial network fission and reconnection of the fragmented network are nucleoid-centric, i.e., fission and new mitochondrial tubule formation are initiated around nucleoids.

We have also used 3D super-resolution fluorescence photoactivated localization microscopy Biplane FPALM to screen a distribution of nucleoid diameters hepatoma HEPG2 cells and found that rather a range of sizes exists up to 300 nm dimensions. We thus have confirmed previous results obtained by 3D interference PALM [3] and excluded simplified data obtained by 2D STED (stimulated depletion emission) [1].

O2k-Network Lab: CZ Prague Jezek P

Labels: MiParea: mt-Structure;fission;fusion, mtDNA;mt-genetics 

Tissue;cell: Other cell lines 

Nucleoid, MiP2013, Hepatoma HEPG2 cells, S05 

Affiliations and author contributions

Institute of Physiology, Academy of Sciences, Prague, Czech Republic. - Email: [email protected]

Supported by GACR grant 13-02033S.


  1. Kukat C, Wurm CA, Spahr H, Falkenberg M, Larsson NG, Jacobs S (2011) Super-resolution microscopy reveals that mammalian mitochondrial nucleoids have a uniform size and frequently contain a single copy of mtDNA. Proc Natl Acad Sci U S A 108: 13534–13539.
  2. Tauber J, Dlasková A, Šantorová J, Smolková K, Alán L, Špaček T, Plecitá-Hlavatá L, Jabůrek M, Ježek P (2013) Distribution of mitochondrial nucleoids upon mitochondrial network fragmentation and network reintegration in HEPG2 cells. Int J Biochem Cell Biol 45: 593-603.
  3. Brown TA, Tkachuk AN, Shtengel G, Kopek BG, Bogenhagen DF, Hess HF, Clayton DA (2011) Superresolution fluorescence imaging of mitochondrial nucleoids reveals their spatial range, limits, and membrane interaction. Mol Cell Biol 31: 4994–5010.

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