scholarly journals Cytoklepty in the plankton: A host strategy to optimize the bioenergetic machinery of endosymbiotic algae

2021 ◽  
Vol 118 (27) ◽  
pp. e2025252118
Author(s):  
Clarisse Uwizeye ◽  
Margaret Mars Brisbin ◽  
Benoit Gallet ◽  
Fabien Chevalier ◽  
Charlotte LeKieffre ◽  
...  
Keyword(s):  
Cell Division ◽  
Carbon Fixation ◽  
Carbon Allocation ◽  
Three Dimensional ◽  
Initial Step ◽  
Evolutionary Trajectory ◽  
Photon Propagation ◽  
Propagation Modeling ◽  
Endosymbiotic Algae ◽  
Oceanic Carbon

Endosymbioses have shaped the evolutionary trajectory of life and remain ecologically important. Investigating oceanic photosymbioses can illuminate how algal endosymbionts are energetically exploited by their heterotrophic hosts and inform on putative initial steps of plastid acquisition in eukaryotes. By combining three-dimensional subcellular imaging with photophysiology, carbon flux imaging, and transcriptomics, we show that cell division of endosymbionts (Phaeocystis) is blocked within hosts (Acantharia) and that their cellular architecture and bioenergetic machinery are radically altered. Transcriptional evidence indicates that a nutrient-independent mechanism prevents symbiont cell division and decouples nuclear and plastid division. As endosymbiont plastids proliferate, the volume of the photosynthetic machinery volume increases 100-fold in correlation with the expansion of a reticular mitochondrial network in close proximity to plastids. Photosynthetic efficiency tends to increase with cell size, and photon propagation modeling indicates that the networked mitochondrial architecture enhances light capture. This is accompanied by 150-fold higher carbon uptake and up-regulation of genes involved in photosynthesis and carbon fixation, which, in conjunction with a ca.15-fold size increase of pyrenoids demonstrates enhanced primary production in symbiosis. Mass spectrometry imaging revealed major carbon allocation to plastids and transfer to the host cell. As in most photosymbioses, microalgae are contained within a host phagosome (symbiosome), but here, the phagosome invaginates into enlarged microalgal cells, perhaps to optimize metabolic exchange. This observation adds evidence that the algal metamorphosis is irreversible. Hosts, therefore, trigger and benefit from major bioenergetic remodeling of symbiotic microalgae with potential consequences for the oceanic carbon cycle. Unlike other photosymbioses, this interaction represents a so-called cytoklepty, which is a putative initial step toward plastid acquisition.

scholarly journals Cytoklepty in the plankton: a host strategy to optimize the bioenergetic machinery of endosymbiotic algae

2020 ◽  
Author(s):  
Uwizeye Clarisse ◽  
Mars Brisbin Margaret ◽  
Gallet Benoit ◽  
Chevalier Fabien ◽  
LeKieffre Charlotte ◽  
...  
Keyword(s):  
Cell Division ◽  
Carbon Fixation ◽  
Carbon Allocation ◽  
Initial Step ◽  
Evolutionary Trajectory ◽  
Photon Propagation ◽  
Propagation Modeling ◽  
Close Proximity ◽  
Endosymbiotic Algae ◽  
Oceanic Carbon

AbstractEndosymbioses have shaped the evolutionary trajectory of life and remain widespread and ecologically important. Investigating modern oceanic photosymbioses can illuminate how algal endosymbionts are energetically exploited by their heterotrophic hosts, and inform on putative initial steps of plastid acquisition in eukaryotes. By combining 3D subcellular imaging with photophysiology, carbon flux imaging and transcriptomics, we show that cell division of algal endosymbionts (Phaeocystis) is blocked within hosts (Acantharia), and that their cellular architecture and bioenergetic machinery are radically altered. Transcriptional evidence indicates that a nutrient-independent mechanism prevents symbiont cell division and decouples nuclear and plastid division. As endosymbiont plastids proliferate, the volume of the photosynthetic machinery volume increases 100-fold in correlation with expansion of a reticular mitochondrial network in close proximity to plastids. Photosynthetic efficiency tends to increase with cell size and photon propagation modeling indicates that the networked mitochondrial architecture enhances light capture. This is accompanied by 150-fold higher carbon uptake and upregulation of genes involved in photosynthesis and carbon fixation, which, in conjunction with a ca.15-fold size increase of pyrenoids demonstrates enhanced primary production in symbiosis. NanoSIMS analysis revealed major carbon allocation to plastids and transfer to the host cell. Invagination of the symbiosome into endosymbionts to optimize metabolic exchanges is strong evidence that the algal metamorphosis is irreversible. Hosts therefore trigger and unambiguously benefit from major bioenergetic remodeling of symbiotic microalgae with important consequences for the oceanic carbon cycle. Unlike other photosymbioses, this interaction represents a so-called cytoklepty, which is a putative initial step towards plastid acquisition.

scholarly journals Flowering plant embryos: How did we end up here?

2021 ◽  
Author(s):  
Stefan A. Rensing ◽  
Dolf Weijers
Keyword(s):  
Current Knowledge ◽  
General Structure ◽  
Three Dimensional ◽  
Flowering Plants ◽  
Flowering Plant ◽  
Adult Plant ◽  
Ancestral State ◽  
Evolutionary Trajectory ◽  
Current State ◽  
Plant Embryo

AbstractThe seeds of flowering plants are sexually produced propagules that ensure dispersal and resilience of the next generation. Seeds harbor embryos, three dimensional structures that are often miniatures of the adult plant in terms of general structure and primordial organs. In addition, embryos contain the meristems that give rise to post-embryonically generated structures. However common, flowering plant embryos are an evolutionary derived state. Flowering plants are part of a much larger group of embryo-bearing plants, aptly termed Embryophyta. A key question is what evolutionary trajectory led to the emergence of flowering plant embryos. In this opinion, we deconstruct the flowering plant embryo and describe the current state of knowledge of embryos in other plant lineages. While we are far yet from understanding the ancestral state of plant embryogenesis, we argue what current knowledge may suggest and how the knowledge gaps may be closed.

scholarly journals Temporal patterns of cell division in natural populations of endosymbiotic algae

1983 ◽  
Vol 28 (5) ◽  
pp. 1009-1014 ◽  
Author(s):  
F. P. Wilkerson ◽  
G. Muller ◽  
Parker L. Muscatine
Keyword(s):  
Cell Division ◽  
Natural Populations ◽  
Temporal Patterns ◽  
Endosymbiotic Algae

Understanding the mechanical link between oriented cell division and cerebellar morphogenesis

Soft Matter ◽  
2019 ◽  
Vol 15 (10) ◽  
pp. 2204-2215 ◽  
Author(s):  
Emma Lejeune ◽  
Berkin Dortdivanlioglu ◽  
Ellen Kuhl ◽  
Christian Linder
Keyword(s):  
Cell Division ◽  
Multiscale Modeling ◽  
Three Dimensional ◽  
Mechanical Instability ◽  
Oriented Cell Division ◽  
Cerebellar Morphogenesis

Three-dimensional multiscale modeling shows that oriented cell division leads to a mechanical instability that can initiate cerebellar foliation.

Analytical Transport Network Theory for Onsager, Coupled Flows: Part 2—Network-Scale Modeling of Linear, Electrokinetic Flow

2020 ◽  
Vol 18 (2) ◽  
Author(s):  
Alex P. Cocco ◽  
Kyle N. Grew
Keyword(s):  
Three Dimensional ◽  
Initial Step ◽  
Transport Network ◽  
Scale Model ◽  
Computationally Efficient ◽  
Coupled Flow ◽  
Electrokinetic Flow ◽  
Network Scale ◽  
Energy Conversion And Storage ◽  
Storage Technologies

Abstract The analytical transport network (ATN) model was developed to study transport through heterogeneous and hierarchical microstructural networks. Here, ATN is extended to electrokinetic flow, a linear, coupled flow that satisfies Onsager’s reciprocity relations. In Part 1, a channel-scale model was developed to describe electrokinetic flow through a channel of arbitrary morphology. In Part 2, we exploit the computational economy of the channel-scale model to develop an efficient network-scale model of electrokinetic flow in large, geometrically complex material structures. The corresponding algorithm for applying the theory to voxel-based, three-dimensional (3D) images is automated and computationally efficient. In addition, it provides a means for rapidly obtaining a structure’s tortuosity factor from a 3D image. We outline the manner in which morphology and topology exerts an additional influence on electrokinetic flow relative to pure conduction and viscous fluid flow. The effort represents an important initial step in extending the ATN approach to a broader range of linear and eventually nonlinear coupled flow phenomena. The extension is relevant to a number of technological fields, including emerging energy conversion and storage technologies.

Three-Dimensional High-Resolution Optical/X-Ray Stereoscopic Tracking Velocimetry

2004 ◽  
Author(s):  
David J. Lee ◽  
Soyoung S. Cha ◽  
Narayanan Ramachandran
Keyword(s):  
Three Dimensional ◽  
Initial Step ◽  
Industrial Applications ◽  
Materials Processing ◽  
Current Status ◽  
Motion Velocity ◽  
Processing Efficiency ◽  
X Ray ◽  
Fluid Physics ◽  
Component Velocity

Measurement of three-dimensional (3-D) three-component velocity fields is of great importance in a variety of research and industrial applications for understanding materials processing, fluid physics, and strain/displacement measurements. The 3-D experiments in these fields most likely inhibit the use of conventional techniques, which are based only on planar and optically-transparent-field observation. Here, we briefly review the current status of 3-D diagnostics for motion/velocity detection, for both optical and x-ray systems. As an initial step for providing 3-D capabilities, we have developed stereoscopic tracking velocimetry (STV) to measure 3-D flow/deformation through optical observation. The STV is advantageous in system simplicity, for continually observing 3-D phenomena in near real-time. In an effort to enhance the data processing through automation and to avoid the confusion in tracking numerous markers or particles, artificial neural networks are employed to incorporate human intelligence. Our initial optical investigations have proven the STV to be a very viable candidate for reliably measuring 3-D flow motions. With previous activities are focused on improving the processing efficiency, overall accuracy, and automation based on the optical system, the current efforts is directed to the concurrent expansion to the x-ray system for broader experimental applications.

Carbon allocation and translocation in chlorsulfuron-treated canola (Brassica napus)

Weed Science ◽  
1997 ◽  
Vol 45 (4) ◽  
pp. 466-469 ◽  
Author(s):  
Songmun Kim ◽  
William H. Vanden Born
Keyword(s):  
Brassica Napus ◽  
Carbon Fixation ◽  
No Reduction ◽  
Carbon Allocation ◽  
Starch Content ◽  
Carbon Exchange ◽  
Net Carbon Exchange

Our objective was to determine if the chlorsulfuron-induced reduction in assimilate export from leaves can be attributed to a shortage of carbohydrates. Treated canola leaves showed no reduction in carbon fixation or carbohydrate production during the first 24 h, but they exuded only 17 to 27% of the amount of sucrose exuded by corresponding control leaves. Exposure of the leaves to higher concentrations of CO2(500 vs. 350 μl L−1) resulted in greater net carbon exchange and higher starch content, but failed to overcome the reduction in sucrose export, presumably because of increased carbon allocation to starch.

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