Paight Christopher

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Last Name
Paight
First Name
Christopher
ORCID
0000-0002-0286-8837

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  • Article
    Cascading effects of prey identity on gene expression in a kleptoplastidic ciliate
    (Wiley, 2022-08-17) Paight, Christopher ; Johnson, Matthew D. ; Lasek-Nesselquist, Erica ; Moeller, Holly V.
    Kleptoplastidic, or chloroplast stealing, lineages transiently retain functional photosynthetic machinery from algal prey. This machinery, and its photosynthetic outputs, must be integrated into the host's metabolism, but the details of this integration are poorly understood. Here, we study this metabolic integration in the ciliate Mesodinium chamaeleon, a coastal marine species capable of retaining chloroplasts from at least six distinct genera of cryptophyte algae. To assess the effects of feeding history on ciliate physiology and gene expression, we acclimated M. chamaeleon to four different types of prey and contrasted well-fed and starved treatments. Consistent with previous physiological work on the ciliate, we found that starved ciliates had lower chlorophyll content, photosynthetic rates, and growth rates than their well-fed counterparts. However, ciliate gene expression mirrored prey phylogenetic relationships rather than physiological status, suggesting that, even as M. chamaeleon cells were starved of prey, their overarching regulatory systems remained tuned to the prey type to which they had been acclimated. Collectively, our results indicate a surprising degree of prey-specific host transcriptional adjustments, implying varied integration of prey metabolic potential into many aspects of ciliate physiology.
  • Article
    Environment-dependent metabolic investments in the mixotrophic chrysophyte Ochromonas
    (Phycological Society of America, 2023-12-23) Barbaglia, Gina S. ; Paight, Christopher ; Honig, Meredith ; Johnson, Matthew D. ; Marczak, Ryan ; Lepori-Bui, Michelle ; Moeller, Holly V.
    Mixotrophic protists combine photosynthesis and phagotrophy to obtain energy and nutrients. Because mixotrophs can act as either primary producers or consumers, they have a complex role in marine food webs and biogeochemical cycles. Many mixotrophs are also phenotypically plastic and can adjust their metabolic investments in response to resource availability. Thus, a single species's ecological role may vary with environmental conditions. Here, we quantified how light and food availability impacted the growth rates, energy acquisition rates, and metabolic investment strategies of eight strains of the mixotrophic chrysophyte, Ochromonas. All eight Ochromonas strains photoacclimated by decreasing chlorophyll content as light intensity increased. Some strains were obligate phototrophs that required light for growth, while other strains showed stronger metabolic responses to prey availability. When prey availability was high, all eight strains exhibited accelerated growth rates and decreased their investments in both photosynthesis and phagotrophy. Photosynthesis and phagotrophy generally produced additive benefits: In low-prey environments, Ochromonas growth rates increased to maximum, light-saturated rates with increasing light but increased further with the addition of abundant bacterial prey. The additive benefits observed between photosynthesis and phagotrophy in Ochromonas suggest that the two metabolic modes provide nonsubstitutable resources, which may explain why a tradeoff between phagotrophic and phototrophic investments emerged in some but not all strains.