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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.


Growth of the prymnesiophyte, Prymnesium parvum, in axenic culture (circles, solid line), in non-axenic culture with attendant bacterial flora (squares, dashed line), and in axenic culture with the addition of ciliates at late exponential phase (triangles, dotted line). Arrow indicates Day 16 when ciliates were added to the axenic P. parvum culture. In the transcriptome experiment, cells were harvested from axenic and bacterized treatment just prior to the addition of ciliates, while cells were harvested from ciliate treatment ~6 h after the addition of ciliates. Symbols and error bars represent mean ± standard deviation of two replicates.
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Figure 1: Growth of the prymnesiophyte, Prymnesium parvum, in axenic culture (circles, solid line), in non-axenic culture with attendant bacterial flora (squares, dashed line), and in axenic culture with the addition of ciliates at late exponential phase (triangles, dotted line). Arrow indicates Day 16 when ciliates were added to the axenic P. parvum culture. In the transcriptome experiment, cells were harvested from axenic and bacterized treatment just prior to the addition of ciliates, while cells were harvested from ciliate treatment ~6 h after the addition of ciliates. Symbols and error bars represent mean ± standard deviation of two replicates.

Mentions: A growth experiment was conducted to determine whether the presence of prey (bacteria or ciliates) had a significant effect on the growth rate or overall yield of P. parvum (Figure 1). Growth rates of the alga were not significantly different (p = 0.20, ANOVA) among the three treatments in early exponential phase (0.36 ± 0.02, 0.42 ± 0.01, 0.38 ± 0.04 d−1 during the first 9 days of the experiment for axenic, bacterized, and ciliate treatment, respectively. Axenic and ciliate treatments did not differ during that period). The addition of ciliates at late exponential phase of the alga on day 16 allowed P. parvum to continue growing (0.12 ± 0.05 d−1) while cultures without ciliates exhibited negligible growth (0.03 ± 0.01 d−1). P. parvum in the bacterized treatment reached the maximum abundance of 4.28 ± 0.03 × 106 cells mL−1, which is slightly higher than that of the axenic treatment (3.80 ± 0.17 × 106 cells mL−1). The addition of ciliates also increased the maximum abundance of P. parvum to (4.95 ± 0.25 × 106 cells mL−1).


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)

Growth of the prymnesiophyte, Prymnesium parvum, in axenic culture (circles, solid line), in non-axenic culture with attendant bacterial flora (squares, dashed line), and in axenic culture with the addition of ciliates at late exponential phase (triangles, dotted line). Arrow indicates Day 16 when ciliates were added to the axenic P. parvum culture. In the transcriptome experiment, cells were harvested from axenic and bacterized treatment just prior to the addition of ciliates, while cells were harvested from ciliate treatment ~6 h after the addition of ciliates. Symbols and error bars represent mean ± standard deviation of two replicates.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Growth of the prymnesiophyte, Prymnesium parvum, in axenic culture (circles, solid line), in non-axenic culture with attendant bacterial flora (squares, dashed line), and in axenic culture with the addition of ciliates at late exponential phase (triangles, dotted line). Arrow indicates Day 16 when ciliates were added to the axenic P. parvum culture. In the transcriptome experiment, cells were harvested from axenic and bacterized treatment just prior to the addition of ciliates, while cells were harvested from ciliate treatment ~6 h after the addition of ciliates. Symbols and error bars represent mean ± standard deviation of two replicates.
Mentions: A growth experiment was conducted to determine whether the presence of prey (bacteria or ciliates) had a significant effect on the growth rate or overall yield of P. parvum (Figure 1). Growth rates of the alga were not significantly different (p = 0.20, ANOVA) among the three treatments in early exponential phase (0.36 ± 0.02, 0.42 ± 0.01, 0.38 ± 0.04 d−1 during the first 9 days of the experiment for axenic, bacterized, and ciliate treatment, respectively. Axenic and ciliate treatments did not differ during that period). The addition of ciliates at late exponential phase of the alga on day 16 allowed P. parvum to continue growing (0.12 ± 0.05 d−1) while cultures without ciliates exhibited negligible growth (0.03 ± 0.01 d−1). P. parvum in the bacterized treatment reached the maximum abundance of 4.28 ± 0.03 × 106 cells mL−1, which is slightly higher than that of the axenic treatment (3.80 ± 0.17 × 106 cells mL−1). The addition of ciliates also increased the maximum abundance of P. parvum to (4.95 ± 0.25 × 106 cells mL−1).

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.