ULTRASTRUCTURAL STUDIES ON THE BLUE-GREEN ALGAL SYMBIONT IN CYANOPHORA PARADOXA KORSCHIKOFF

Hall, William S.; Claus, George

doi:10.1083/jcb.19.3.551

Cited by 151 publications

(50 citation statements)

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“…Cyanophora paradoxa is a glaucophyte biflagellate assumed to have the most primitive features among the photosynthetic eukaryotes (Hall and Claus 1963, Mignot et al 1969, Spiegel 2012. This alga has been examined extensively as a model organism of primitive phototrophs (e.g.…”

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confidence: 99%

“…Sato et al 2005, Watanabe et al 2009, Frassanito et al 2010, Leblond et al 2010, Facchinelli et al 2013. Ultrastructural features of C. paradoxa were examined using transmission and scanning electron microscopy (TEM and SEM, respectively) to demonstrate that the cell periphery lacks a cell wall but consists of plasma membrane and flattened vesicles containing a plate just underneath the membrane (Hall and Claus 1963, Mignot et al 1969, Trench et al 1978, Kies 1979, Kugrens et al 1999. Using conventional SEM, Kugrens et al (1999) examined two species of Cyanophora.…”

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Surface Ornamentation of Cyanophora paradoxa (Cyanophorales, Glaucophyta) Cells as Revealed by Ultra-High Resolution Field Emission Scanning Electron Microscopy

et al. 2014

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Summary Cyanophora paradoxa is an enigmatic biflagellate that may represent the first photosynthetic eukaryote morphologically. This alga has been widely studied as a model organism of primitive phototrophs. However, surface ornamentations of the vegetative cells have not been examined using ultra-high resolution field emission (FE) scanning electron microscopy (SEM). In the present study, C. paradoxa NIES-547 vegetative cells were examined using FE-SEM and compared with the data using conventional SEM. Our FE-SEM images demonstrated that the cell surface was ornamented with angular fenestrations framed by ridges. In contrast, conventional SEM did not reveal similar surface ornamentation. Transmission electron microscopy showed the ridge was formed by the edges of overlapping or attaching outermost plate vesicles at the cell periphery.

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Surface Ornamentation of Cyanophora paradoxa (Cyanophorales, Glaucophyta) Cells as Revealed by Ultra-High Resolution Field Emission Scanning Electron Microscopy

et al. 2014

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“…In the atypical case of Gloeobacter violaceus, the phycobilisomes are attached to the plasma membrane (15). The cyanelles of Cyanophora paradoxa are generally regarded as cyanobacterial endosymbionts within a flagellated unicellular eukaryote (16,30,34). According to the endosymbiotic theory of the origin of chloroplasts, associations such as that found in Cyanophora could have been an intermediate step in the evolution of red algal chloroplasts (24,25,32).…”

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Structure of the Thylakoids and Envelope Membranes of the Cyanelles of Cyanophora paradoxa

Giddings¹,

Wasmann²,

Staehelin³

1983

Plant Physiol.

121

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The cyanelles of Cyanophora paradoxa Korsch. are photosynthetically active obligate endosymbionts in which phycobiliproteins serve as the major accessory pigments. Freeze-fracture electron micrographs of thylakoids in isolated cyanelies reveal long parallel rows of particles covering most of the E-face, while a more random particle arrangement is evident in some areas. The center-to-center spacing of particles within these rows is about 10 nanometers. Their mean diameter was measured at 9.4 nanometers. The particles on the P-face have a mean diameter of 7.2 nanometers. Thylakoids that retained nearly the full complement of phycobiliproteins (determined spectrophotometrically and by gel electrophoresis) were isolated from the cyanelies. In thin sections of these preparations, rows of disc-shaped phycobilisomes are evident on the surface of the thylakoids. The spacing of the rows of phycobilisomes corresponds to that of the rows of E-face particles (approximately 45 nanometers, center to center). The periodicity of the disc-shaped phycobilisomes within a row is 10 nanometers suggesting a one-to-one association between phycobilisomes and E-face particles.In addition, visualization of the protoplasmic surface (PS) of isolated thylakoids by freeze-etch electron microscopy shows that rows of discshaped phycobilisomes are aligned directly above rows of particles exhibiting two subunits, presumably the P-surface projections of the 10-nanometer intramembrane particles. These observations, together with earlier studies indicating that the 10-nanometer E-face particles probably represent photosystem II (PSII) complexes, suggest that phycobilisomes are positioned on the thylakoid surface in direct contact with PSII centers within the thylakoid membrane.The inner envelope membrane of the cyanelles, observed in freezefracture replicas, resembles cyanobacterial plasma membranes and is dissimilar to the chloroplast envelope membranes of red or green algae.The envelope of isolated cyanelies exhibits two additional layers: (a) a 5-to 7-nanometer-thick layer that lies adjacent to the inner membrane and which seems to correspond to the peptidoglycan layer of cyanobacteria; and (b) a layer external to the purported peptidoglycan layer that exhibits fracture faces similar to those of the lipopolysaccharide layer of gram negative bacteria. Our findings indicate that the supramolecular architecture of cyanelles differs only slightly from free-living cyanobacteria to which they are presumably related.Cyanobacteria, red algal chloroplasts and certain cyanobacteria- like endosymbionts, termed cyanelles, employ phycobiliproteins attached to the outer surface of their thylakoids as the major lightharvesting pigments for 02-evolving photosynthesis (3,7,10,29,35). In the atypical case of Gloeobacter violaceus, the phycobilisomes are attached to the plasma membrane (15). The cyanelles of Cyanophora paradoxa are generally regarded as cyanobacterial endosymbionts within a flagellated unicellular eukaryote (16,30,34). According to the end...

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“…Authors of seminal studies described the glaucophyte plastids as "protoplasm colored bodies", "endosymbiotic blue-green photosynthesizing prokaryotes", "prokaryotic blue-green endocytobionts" or "endocyanomes". Some of these studies even described the blue-green plastids as cyanobacterial species [54] and highlighted their "intermediate" characteristics between free-living cells and organelles [55,56]. Further molecular studies demonstrated that the glaucophyte blue-green "bodies" are photosynthetic organelles [57][58][59].…”

Section: The Defining Characteristics Of Glaucophytamentioning

confidence: 99%

“…2) [54,60]. These latter two traits are considered plesiomorphic characters for Archaeplastida that have been uniquely retained in glaucophytes (extended descriptions of these two traits are provided in the section "The blue-green plastids of glaucophytes" below).…”

Section: The Defining Characteristics Of Glaucophytamentioning

confidence: 99%

The Glaucophyta: the blue-green plants in a nutshell

2015

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The Glaucophyta is one of the three major lineages of photosynthetic eukaryotes, together with viridiplants and red algae, united in the presumed monophyletic supergroup Archaeplastida. Glaucophytes constitute a key algal lineage to investigate both the origin of primary plastids and the evolution of algae and plants. Glaucophyte plastids possess exceptional characteristics retained from their cyanobacterial ancestor: phycobilisome antennas, a vestigial peptidoglycan wall, and carboxysome-like bodies. These latter two traits are unique among the Archaeplastida and have been suggested as evidence that the glaucophytes diverged earliest during the diversification of this supergroup. Our knowledge of glaucophytes is limited compared to viridiplants and red algae, and this has restricted our capacity to untangle the early evolution of the Archaeplastida. However, in recent years novel genomic and functional data are increasing our understanding of glaucophyte biology. Diverse comparative studies using information from the nuclear genome of Cyanophora paradoxa and recent transcriptomic data from other glaucophyte species provide support for the common origin of Archaeplastida. Molecular and ultrastructural studies have revealed previously unrecognized diversity in the genera Cyanophora and Glaucocystis. Overall, a series of recent findings are modifying our perspective of glaucophyte diversity and providing fresh approaches to investigate the basic biology of this rare algal group in detail.

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ULTRASTRUCTURAL STUDIES ON THE BLUE-GREEN ALGAL SYMBIONT IN CYANOPHORA PARADOXA KORSCHIKOFF

Cited by 151 publications

References 5 publications

Surface Ornamentation of <i>Cyanophora paradoxa</i> (Cyanophorales, Glaucophyta) Cells as Revealed by Ultra-High Resolution Field Emission Scanning Electron Microscopy

Surface Ornamentation of <i>Cyanophora paradoxa</i> (Cyanophorales, Glaucophyta) Cells as Revealed by Ultra-High Resolution Field Emission Scanning Electron Microscopy

Structure of the Thylakoids and Envelope Membranes of the Cyanelles of Cyanophora paradoxa

The Glaucophyta: the blue-green plants in a nutshell

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