Publications by authors named "Motoki Kayama"
Secondary loss of photosynthesis is observed across almost all plastid-bearing branches of the eukaryotic tree of life. However, genome-based insights into the transition from a phototroph into a secondary heterotroph have so far only been revealed for parasitic species. Free-living organisms can yield unique insights into the evolutionary consequence of the loss of photosynthesis, as the parasitic lifestyle requires specific adaptations to host environments.
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- Ochrophyta, a group of algae in the Stramenopiles, plays a key role in ocean ecosystems but its early evolution of the plastid organelle is still unclear.
- This study reveals that Actinophrys sol, a non-photosynthetic protist, is closely related to Ochrophyta and shows no evidence of plastids despite sharing some algal genes, suggesting past gene transfer.
- The findings indicate that the ancestor of Actinophryidae and Ochrophyta had not fully established the plastid partnership seen in modern Ochrophyta, retaining genes necessary for plastid function but without the organelle itself.
Rapidly accumulating genetic data from environmental sequencing approaches have revealed an extraordinary level of unsuspected diversity within marine phytoplankton, which is responsible for around 50% of global net primary production. However, the phenotypic identity of many of the organisms distinguished by environmental DNA sequences remains unclear. The rappemonads represent a plastid-bearing protistan lineage that to date has only been identified by environmental plastid 16S rRNA sequences.
View Article and Find Full Text PDFOrganisms that have lost their photosynthetic capabilities are present in a variety of eukaryotic lineages, such as plants and disparate algal groups. Most of such non-photosynthetic eukaryotes still carry plastids, as these organelles retain essential biological functions. Most non-photosynthetic plastids possess genomes with varied protein-coding contents.
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- - The study investigates non-photosynthetic plastids in green algae, specifically a strain of Chlamydomonas, which retains some components of electron transport systems despite lacking photosynthesis-related structures.
- - Researchers found that this alga has retained the ability to synthesize carotenoids and plastoquinol, but not chlorophyll, and identified key genes involved in electron transport and redox homeostasis.
- - The findings suggest that the electron sink system, crucial for managing excess electrons, is more widespread in non-photosynthetic plastids across various algal and plant species than previously understood.
Article Synopsis
- Eukaryotic ecology mainly relies on oxygenic photosynthesis, driven by chlorophylls, which can be both beneficial for energy harvesting and harmful due to reactive oxygen species.
- The research shows that a widespread process called chlorophyll catabolism converts chlorophylls into non-toxic forms (CPEs) among various microeukaryotes, except for Archaeplastida.
- This catabolism likely evolved in algivorous microeukaryotes to detoxify chlorophylls and played a crucial role in photosynthetic endosymbiosis, enabling the diversification of eukaryotes following increased oxygen levels in the environment.
In vivo and in vitro preparation of divinyl-13,17-cyclopheophorbide-a enol.
Bioorg Med Chem Lett
April 2018
Article Synopsis
- Divinyl-13,17-cyclopheophorbide-a enol is a compound produced both naturally by protists and synthetically in the lab from a derivative of divinyl-chlorophyll-a.
- Analysis using H NMR spectroscopy revealed that this compound primarily exists in its enol form in solution.
- The process of intramolecular cyclization at specific positions altered the compound's optical properties, leading to a lack of fluorescent emission from the enol form.