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Gene expression in the mixotrophic prymnesiophyte, Prymnesium parvum, responds to prey availability.

Liu Z, Jones AC, Campbell V, Hambright KD, Heidelberg KB, Caron DA - Front Microbiol (2015)

Bottom Line: It produces toxins and can form ecosystem disruptive blooms that result in fish kills and changes in planktonic food web structure.However, both transcriptomic data and growth experiments indicated that P. parvum did not grow faster in the presence of prey despite the gains in nutrients, although algal abundances attained in culture were slightly greater in the presence of prey.The relationship between phototrophy, heterotrophy and growth of P. parvum is discussed.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Southern California Los Angeles, CA, USA.

ABSTRACT
The mixotrophic prymnesiophyte, Prymnesium parvum, is a widely distributed alga with significant ecological importance. It produces toxins and can form ecosystem disruptive blooms that result in fish kills and changes in planktonic food web structure. However, the relationship between P. parvum and its prey on the molecular level is poorly understood. In this study, we used RNA-Seq technology to study changes in gene transcription of P. parvum in three treatments with different microbial populations available as potential prey: axenic P. parvum (no prey), bacterized P. paruvm, and axenic P. parvum with ciliates added as prey. Thousands of genes were differentially expressed among the three treatments. Most notably, transcriptome data indicated that P. parvum obtained organic carbon, including fatty acids, from both bacteria and ciliate prey for energy and cellular building blocks. The data also suggested that different prey provided P. parvum with macro- and micro-nutrients, namely organic nitrogen in the form of amino acids from ciliates, and iron from bacteria. However, both transcriptomic data and growth experiments indicated that P. parvum did not grow faster in the presence of prey despite the gains in nutrients, although algal abundances attained in culture were slightly greater in the presence of prey. The relationship between phototrophy, heterotrophy and growth of P. parvum is discussed.

No MeSH data available.


Related in: MedlinePlus

Cellular overview of gene transcription of Prymnesium parvum under three treatments and hypothetical model of metabolic activities. Transcription levels of select genes, pathways or functions in bacterized and ciliate treatments relative to axenic treatment are shown. Blue shaded arrows and crosses indicate proposed model of metabolic flows and suppression of functions of P. parvum, respectively, in response to the presence of bacteria in the bacterized treatment. Red shaded arrows and crosses indicate the same flows and suppressions in response to the presence of ciliates in the ciliate treatment. Cellular localizations of proteins are based on knowledge of homologs in other protists or in silico predictions.
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Figure 5: Cellular overview of gene transcription of Prymnesium parvum under three treatments and hypothetical model of metabolic activities. Transcription levels of select genes, pathways or functions in bacterized and ciliate treatments relative to axenic treatment are shown. Blue shaded arrows and crosses indicate proposed model of metabolic flows and suppression of functions of P. parvum, respectively, in response to the presence of bacteria in the bacterized treatment. Red shaded arrows and crosses indicate the same flows and suppressions in response to the presence of ciliates in the ciliate treatment. Cellular localizations of proteins are based on knowledge of homologs in other protists or in silico predictions.

Mentions: Expression patterns of glycolysis/gluconeogenesis genes were inconsistent among themselves. However, genes involved in the connection between glycolysis/gluconeogenesis and other carbon pathways had interesting expression patterns. Genes encoding pyruvate carboxylase and PEP carboxykinase had slightly higher expression levels in the bacterized treatment, and even higher levels in the ciliate treatment. These two proteins convert pyruvate and TCA cycle metabolites through oxaloacetate to PEP, and are generally regarded as gluconeogenic enzymes. Conversely, PEP carboxylase, which operates in the opposite direction of PEP carboxykinase, decreased significantly in its transcription level in the ciliate treatment (Figure 5, Table S2).


Gene expression in the mixotrophic prymnesiophyte, Prymnesium parvum, responds to prey availability.

Liu Z, Jones AC, Campbell V, Hambright KD, Heidelberg KB, Caron DA - Front Microbiol (2015)

Cellular overview of gene transcription of Prymnesium parvum under three treatments and hypothetical model of metabolic activities. Transcription levels of select genes, pathways or functions in bacterized and ciliate treatments relative to axenic treatment are shown. Blue shaded arrows and crosses indicate proposed model of metabolic flows and suppression of functions of P. parvum, respectively, in response to the presence of bacteria in the bacterized treatment. Red shaded arrows and crosses indicate the same flows and suppressions in response to the presence of ciliates in the ciliate treatment. Cellular localizations of proteins are based on knowledge of homologs in other protists or in silico predictions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4403553&req=5

Figure 5: Cellular overview of gene transcription of Prymnesium parvum under three treatments and hypothetical model of metabolic activities. Transcription levels of select genes, pathways or functions in bacterized and ciliate treatments relative to axenic treatment are shown. Blue shaded arrows and crosses indicate proposed model of metabolic flows and suppression of functions of P. parvum, respectively, in response to the presence of bacteria in the bacterized treatment. Red shaded arrows and crosses indicate the same flows and suppressions in response to the presence of ciliates in the ciliate treatment. Cellular localizations of proteins are based on knowledge of homologs in other protists or in silico predictions.
Mentions: Expression patterns of glycolysis/gluconeogenesis genes were inconsistent among themselves. However, genes involved in the connection between glycolysis/gluconeogenesis and other carbon pathways had interesting expression patterns. Genes encoding pyruvate carboxylase and PEP carboxykinase had slightly higher expression levels in the bacterized treatment, and even higher levels in the ciliate treatment. These two proteins convert pyruvate and TCA cycle metabolites through oxaloacetate to PEP, and are generally regarded as gluconeogenic enzymes. Conversely, PEP carboxylase, which operates in the opposite direction of PEP carboxykinase, decreased significantly in its transcription level in the ciliate treatment (Figure 5, Table S2).

Bottom Line: It produces toxins and can form ecosystem disruptive blooms that result in fish kills and changes in planktonic food web structure.However, both transcriptomic data and growth experiments indicated that P. parvum did not grow faster in the presence of prey despite the gains in nutrients, although algal abundances attained in culture were slightly greater in the presence of prey.The relationship between phototrophy, heterotrophy and growth of P. parvum is discussed.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Southern California Los Angeles, CA, USA.

ABSTRACT
The mixotrophic prymnesiophyte, Prymnesium parvum, is a widely distributed alga with significant ecological importance. It produces toxins and can form ecosystem disruptive blooms that result in fish kills and changes in planktonic food web structure. However, the relationship between P. parvum and its prey on the molecular level is poorly understood. In this study, we used RNA-Seq technology to study changes in gene transcription of P. parvum in three treatments with different microbial populations available as potential prey: axenic P. parvum (no prey), bacterized P. paruvm, and axenic P. parvum with ciliates added as prey. Thousands of genes were differentially expressed among the three treatments. Most notably, transcriptome data indicated that P. parvum obtained organic carbon, including fatty acids, from both bacteria and ciliate prey for energy and cellular building blocks. The data also suggested that different prey provided P. parvum with macro- and micro-nutrients, namely organic nitrogen in the form of amino acids from ciliates, and iron from bacteria. However, both transcriptomic data and growth experiments indicated that P. parvum did not grow faster in the presence of prey despite the gains in nutrients, although algal abundances attained in culture were slightly greater in the presence of prey. The relationship between phototrophy, heterotrophy and growth of P. parvum is discussed.

No MeSH data available.


Related in: MedlinePlus