scholarly journals Overexpression of Key Sterol Pathway Enzymes in Two Model Marine Diatoms Alters Sterol Profiles in Phaeodactylum tricornutum

2020 ◽  
Vol 13 (12) ◽  
pp. 481
Author(s):  
Ana Cristina Jaramillo-Madrid ◽  
Raffaela Abbriano ◽  
Justin Ashworth ◽  
Michele Fabris ◽  
Mathieu Pernice ◽  
...  
Keyword(s):  
Intracellular Signaling ◽  
Phaeodactylum Tricornutum ◽  
Metabolic Flux ◽  
Total Sterol ◽  
Sterol Composition ◽  
Thalassiosira Pseudonana ◽  
Squalene Epoxidase ◽  
End Point ◽  
Eukaryotic Phytoplankton ◽  
Coa Reductase

Sterols are a class of triterpenoid molecules with diverse functional roles in eukaryotic cells, including intracellular signaling and regulation of cell membrane fluidity. Diatoms are a dominant eukaryotic phytoplankton group that produce a wide diversity of sterol compounds. The enzymes 3-hydroxy-3-methyl glutaryl CoA reductase (HMGR) and squalene epoxidase (SQE) have been reported to be rate-limiting steps in sterol biosynthesis in other model eukaryotes; however, the extent to which these enzymes regulate triterpenoid production in diatoms is not known. To probe the role of these two metabolic nodes in the regulation of sterol metabolic flux in diatoms, we independently over-expressed two versions of the native HMGR and a conventional, heterologous SQE gene in the diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum. Overexpression of these key enzymes resulted in significant differential accumulation of downstream sterol pathway intermediates in P. tricornutum. HMGR-mVenus overexpression resulted in the accumulation of squalene, cycloartenol, and obtusifoliol, while cycloartenol and obtusifoliol accumulated in response to heterologous NoSQE-mVenus overexpression. In addition, accumulation of the end-point sterol 24-methylenecholesta-5,24(24’)-dien-3β-ol was observed in all P. tricornutum overexpression lines, and campesterol increased three-fold in P. tricornutum lines expressing NoSQE-mVenus. Minor differences in end-point sterol composition were also found in T. pseudonana, but no accumulation of sterol pathway intermediates was observed. Despite the successful manipulation of pathway intermediates and individual sterols in P. tricornutum, total sterol levels did not change significantly in transformed lines, suggesting the existence of tight pathway regulation to maintain total sterol content.

scholarly journals Overexpression of key sterol pathway enzymes in two model marine diatoms alters sterol profiles in Phaeodactylum tricornutum

2020 ◽  
Author(s):  
Ana Cristina Jaramillo-Madrid ◽  
Raffaela Abbriano ◽  
Justin Ashworth ◽  
Michele Fabris ◽  
Peter J. Ralph
Keyword(s):  
Intracellular Signaling ◽  
Phaeodactylum Tricornutum ◽  
Metabolic Flux ◽  
Total Sterol ◽  
Sterol Composition ◽  
Thalassiosira Pseudonana ◽  
Squalene Epoxidase ◽  
End Point ◽  
Eukaryotic Phytoplankton ◽  
Coa Reductase

AbstractSterols are a class of triterpenoid molecules with diverse functional roles in eukaryotic cells, including intracellular signaling and regulation of cell membrane fluidity. Diatoms are a dominant eukaryotic phytoplankton group that produce a wide diversity of sterol compounds. The enzymes 3-hydroxy-3-methyl glutaryl CoA reductase (HMGR) and squalene epoxidase (SQE) have been reported to be rate-limiting steps in sterol biosynthesis in other model eukaryotes; however, the extent to which these enzymes regulate triterpenoid production in diatoms is not known. To probe the role of these two metabolic nodes in the regulation of sterol metabolic flux in diatoms, we independently over-expressed two versions of the native HMGR and a conventional, heterologous SQE gene in the diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum. Overexpression of these key enzymes resulted in significant differential accumulation of downstream sterol pathway intermediates in P. tricornutum. HMGR-mVenus overexpression resulted in the accumulation of squalene, cycloartenol, and obtusifoliol, while cycloartenol and obtusifoliol accumulated in response to heterologous NoSQE-mVenus overexpression. In addition, accumulation of the end-point sterol 24-methylenecholesta-5,24(24’)-dien-3β-ol was observed in all P. tricornutum overexpression lines, and campesterol increased 3-fold in P. tricornutum lines expressing NoSQE-mVenus. Minor differences in end-point sterol composition were also found in T. pseudonana, but no accumulation of sterol pathway intermediates was observed. Despite the successful manipulation of pathway intermediates and individual sterols in P. tricornutum, total sterol levels did not change significantly in transformed lines, suggesting the existence of tight pathway regulation to maintain total sterol content.

Changes in sterol composition with ontogeny of Blumeria graminis conidia

2000 ◽  
Vol 78 (10) ◽  
pp. 1288-1293 ◽  
Author(s):  
Jérôme Muchembled ◽  
Anissa Lounès-Hadj Sahraoui ◽  
Anne Grandmougin-Ferjani ◽  
Michel Sancholle
Keyword(s):  
Powdery Mildew ◽  
Plant Pathogen ◽  
Total Sterol ◽  
Sterol Composition ◽  
Blumeria Graminis ◽  
Erysiphe Graminis ◽  
Qualitative And Quantitative ◽  
Wheat Powdery Mildew

The total sterol composition of conidia of the obligate plant pathogen Blumeria (= Erysiphe) graminis f.sp. tritici has been analysed as a function of their ontogeny during sporulation. Two main classes of sterols were characterized: 24-ethylsterols (24-ethylcholesta-5,22-dienol, 24-ethylcholesterol, and Δ5-avenasterol) and 24-methylsterols (24-methylenecholesterol and episterol). Our results show that sterol composition is greatly modified during ontogeny of B. graminis conidia both at the qualitative and quantitative levels. In particular, 24-methylsterols, e.g., 24-methylenecholesterol and episterol, are the major sterols in old conidia whereas 24-ethylsterols, e.g., 24-ethylcholesta-5,22-dienol, 24-ethylcholesterol, and Δ5-avenasterol, are the main sterols in young conidia.Key words: Erysiphe, wheat powdery mildew, sterols, ontogeny.

scholarly journals The iron-sulfur scaffold protein HCF101 unveils the complexity of organellar evolution in SAR, Haptista and Cryptista

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jan Pyrih ◽  
Vojtěch Žárský ◽  
Justin D. Fellows ◽  
Christopher Grosche ◽  
Dorota Wloga ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Complex I ◽  
Phaeodactylum Tricornutum ◽  
Tetrahymena Thermophila ◽  
Thalassiosira Pseudonana ◽  
Cellular Distribution ◽  
Iron Sulfur Cluster ◽  
Iron Sulfur ◽  
Secondary Plastids ◽  
Respiratory Complex I

Abstract Background Nbp35-like proteins (Nbp35, Cfd1, HCF101, Ind1, and AbpC) are P-loop NTPases that serve as components of iron-sulfur cluster (FeS) assembly machineries. In eukaryotes, Ind1 is present in mitochondria, and its function is associated with the assembly of FeS clusters in subunits of respiratory Complex I, Nbp35 and Cfd1 are the components of the cytosolic FeS assembly (CIA) pathway, and HCF101 is involved in FeS assembly of photosystem I in plastids of plants (chHCF101). The AbpC protein operates in Bacteria and Archaea. To date, the cellular distribution of these proteins is considered to be highly conserved with only a few exceptions. Results We searched for the genes of all members of the Nbp35-like protein family and analyzed their targeting sequences. Nbp35 and Cfd1 were predicted to reside in the cytoplasm with some exceptions of Nbp35 localization to the mitochondria; Ind1was found in the mitochondria, and HCF101 was predicted to reside in plastids (chHCF101) of all photosynthetically active eukaryotes. Surprisingly, we found a second HCF101 paralog in all members of Cryptista, Haptista, and SAR that was predicted to predominantly target mitochondria (mHCF101), whereas Ind1 appeared to be absent in these organisms. We also identified a few exceptions, as apicomplexans possess mHCF101 predicted to localize in the cytosol and Nbp35 in the mitochondria. Our predictions were experimentally confirmed in selected representatives of Apicomplexa (Toxoplasma gondii), Stramenopila (Phaeodactylum tricornutum, Thalassiosira pseudonana), and Ciliophora (Tetrahymena thermophila) by tagging proteins with a transgenic reporter. Phylogenetic analysis suggested that chHCF101 and mHCF101 evolved from a common ancestral HCF101 independently of the Nbp35/Cfd1 and Ind1 proteins. Interestingly, phylogenetic analysis supports rather a lateral gene transfer of ancestral HCF101 from bacteria than its acquisition being associated with either α-proteobacterial or cyanobacterial endosymbionts. Conclusion Our searches for Nbp35-like proteins across eukaryotic lineages revealed that SAR, Haptista, and Cryptista possess mitochondrial HCF101. Because plastid localization of HCF101 was only known thus far, the discovery of its mitochondrial paralog explains confusion regarding the presence of HCF101 in organisms that possibly lost secondary plastids (e.g., ciliates, Cryptosporidium) or possess reduced nonphotosynthetic plastids (apicomplexans).

Phaeodactylum tricornutum photosynthesis and Thalassiosira pseudonana bio-silica formation genes nucleotide fluctuations

2008 ◽  
Author(s):  
Todd Holden ◽  
P. Marchese ◽  
G. Tremberger, Jr. ◽  
E. Cheung ◽  
R. Subramaniam ◽  
...  
Keyword(s):  
Phaeodactylum Tricornutum ◽  
Thalassiosira Pseudonana

scholarly journals Integrative analysis of large scale transcriptome data draws a comprehensive functional landscape of Phaeodactylum tricornutum genome and evolutionary origin of diatoms

2017 ◽  
Author(s):  
Achal Rastogi ◽  
Uma Maheswari ◽  
Richard G. Dorrell ◽  
Florian Maumus ◽  
Fabio Rocha Jimenez Vieira ◽  
...  
Keyword(s):  
Phaeodactylum Tricornutum ◽  
Large Scale ◽  
De Novo ◽  
Intron Retention ◽  
Exon Skipping ◽  
Growth Conditions ◽  
Reference Sequence ◽  
Evolutionary Origins ◽  
Eukaryotic Phytoplankton ◽  
Solid Foundation

AbstractDiatoms are one of the most successful and ecologically important groups of eukaryotic phytoplankton in the modern ocean. Deciphering their genomes is a key step towards better understanding of their biological innovations, evolutionary origins, and ecological underpinnings. Here, we have used 90 RNA-Seq datasets from different growth conditions combined with published expressed sequence tags and protein sequences from multiple taxa to explore the genome of the model diatom Phaeodactylum tricornutum, and introduce 1,489 novel genes. The new annotation additionally permitted the discovery for the first time of extensive alternative splicing (AS) in diatoms, including intron retention and exon skipping which increases the diversity of transcripts to regulate gene expression in response to nutrient limitations. In addition, we have used up-to-date reference sequence libraries to dissect the taxonomic origins of diatom genomes. We show that the P. tricornutum genome is replete in lineage-specific genes, with up to 47% of the gene models present only possessing orthologues in other stramenopile groups. Finally, we have performed a comprehensive de novo annotation of repetitive elements showing novel classes of TEs such as SINE, MITE, LINE and TRIM/LARD. This work provides a solid foundation for future studies of diatom gene function, evolution and ecology.

scholarly journals Levels of Diatom Minor Sterols Respond to Changes in Temperature and Salinity

2020 ◽  
Vol 8 (2) ◽  
pp. 85 ◽  
Author(s):  
Ana Cristina Jaramillo-Madrid ◽  
Justin Ashworth ◽  
Peter J. Ralph
Keyword(s):  
Human Health ◽  
Phaeodactylum Tricornutum ◽  
Thalassiosira Pseudonana ◽  
Eukaryotic Cells ◽  
Effect Of Temperature ◽  
Diatom Species ◽  
Adaptive Traits ◽  
Chaetoceros Muelleri ◽  
Diverse Range ◽  
The Relationship

Diatoms are a broadly distributed and evolutionarily diversified group of microalgae that produce a diverse range of sterol compounds. Sterols are triterpenoids that play essential roles in membrane-related processes in eukaryotic cells. Some sterol compounds possess bioactivities that promote human health and are currently used as nutraceuticals. The relationship between sterol diversity in diatoms and their acclimation to different environments is not well understood. In this study, we investigated the occurrence of different sterol types across twelve diatom species, as well as the effect of temperature reduction and changes in salinity on the sterol contents of three model diatom species. In the diatoms Thalassiosira pseudonana, Phaeodactylum tricornutum and Chaetoceros muelleri, we found that changes in the relative contents of minor sterols accompanied shifts in temperature and salinity. This may be indicative of acquired adaptive traits in diatom metabolism.

scholarly journals Cloning of Thalassiosira pseudonana’s Mitochondrial Genome in Saccharomyces cerevisiae and Escherichia coli

Biology ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 358
Author(s):  
Ryan R. Cochrane ◽  
Stephanie L. Brumwell ◽  
Arina Shrestha ◽  
Daniel J. Giguere ◽  
Samir Hamadache ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Mitochondrial Genome ◽  
Phaeodactylum Tricornutum ◽  
Genome Engineering ◽  
Genome Instability ◽  
Thalassiosira Pseudonana ◽  
Genome Integrity ◽  
Mitochondrial Genomes ◽  
E Coli

Algae are attractive organisms for biotechnology applications such as the production of biofuels, medicines, and other high-value compounds due to their genetic diversity, varied physical characteristics, and metabolic processes. As new species are being domesticated, rapid nuclear and organelle genome engineering methods need to be developed or optimized. To that end, we have previously demonstrated that the mitochondrial genome of microalgae Phaeodactylum tricornutum can be cloned and engineered in Saccharomyces cerevisiae and Escherichia coli. Here, we show that the same approach can be used to clone mitochondrial genomes of another microalga, Thalassiosira pseudonana. We have demonstrated that these genomes can be cloned in S. cerevisiae as easily as those of P. tricornutum, but they are less stable when propagated in E. coli. Specifically, after approximately 60 generations of propagation in E. coli, 17% of cloned T. pseudonana mitochondrial genomes contained deletions compared to 0% of previously cloned P. tricornutum mitochondrial genomes. This genome instability is potentially due to the lower G+C DNA content of T. pseudonana (30%) compared to P. tricornutum (35%). Consequently, the previously established method can be applied to clone T. pseudonana’s mitochondrial genome, however, more frequent analyses of genome integrity will be required following propagation in E. coli prior to use in downstream applications.

scholarly journals Produção de biomassa e teores de carbono, hidrogênio, nitrogênio e proteína em microalgas

2009 ◽  
Vol 39 (6) ◽  
pp. 1760-1767 ◽  
Author(s):  
Silvana Ohse ◽  
Roberto Bianchini Derner ◽  
Renata Ávila Ozório ◽  
Maurício Villela Da Costa Braga ◽  
Paulo Cunha ◽  
...  
Keyword(s):  
Chlorella Vulgaris ◽  
Phaeodactylum Tricornutum ◽  
Isochrysis Galbana ◽  
Nannochloropsis Oculata ◽  
Thalassiosira Pseudonana ◽  
Tetraselmis Suecica ◽  
Chaetoceros Muelleri ◽  
Santa Catarina ◽  
Tetraselmis Chuii

O aumento da emissão de CO2 e de outros gases efeito estufa tem gerado debates em nível mundial sobre alterações climáticas e estimulado o desenvolvimento de estratégias mitigadoras. Trabalhos nessa área incluem sequestro de CO2 por meio da produção de microalgas aquáticas. Por essa razão, desenvolveu-se um estudo visando determinar os teores de carbono, hidrogênio, nitrogênio e proteína e a produção de biomassa seca de nove espécies de microalgas marinhas (Nannochloropsis oculata, Thalassiosira pseudonana, Phaeodactylum tricornutum, Isochrysis galbana, Tetraselmis suecica, Tetraselmis chuii Chaetoceros muelleri, Thalassiosira fluviatilis e Isochrysis sp.) e uma de água doce (Chlorella vulgaris), em cultivo autotrófico estacionário com objetivo de identificar as mais produtivas e com maior capacidade de fixação de carbono. O experimento foi desenvolvido em sala de cultivo, na Universidade Federal de Santa Catarina, com iluminação contínua e radiação em torno de 150µmol m-2 s-1, temperatura de 25±2°C, suplementação de ar constante, sendo utilizados erlenmeyers com 800mL de meio de cultura. O delineamento experimental foi de blocos casualizados no tempo com três repetições. As espécies C. vulgaris e T. suecica são menos produtivas. Quando se visa à suplementação alimentar, as espécies C. vulgaris e T. Chuii são consideradas interessantes, uma vez que apresentam altos teores de C, N, H e proteína. As espécies N. Oculata, T. pseudonana e C. vulgaris apresentam altos teores de C, demonstrando alta capacidade de fixação de carbono.

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