Almada Amalia A.

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Amalia A.

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  • Preprint
    Vibrio elicits targeted transcriptional responses from copepod hosts
    ( 2016-05) Almada, Amalia A. ; Tarrant, Ann M.
    Copepods are abundant crustaceans that harbor diverse bacterial communities, yet the nature of their interactions with microbiota are poorly understood . Here, we report that Vibrio elicits targeted transcriptional responses in the estuarine copepod Eurytemora affinis. We pre-treated E. affinis with an antibiotic-cocktail and exposed them to either a zooplankton specialist (Vibrio sp. F10 9ZB36) or a free-living species (V. ordalii 12B09) for 24 hours. We then identified via RNA-Seq a total of 78 genes that were differentially expressed following Vibrio exposure, including homologs of C-type lectins, chitin-binding proteins and saposins. The response differed between the two Vibrio treatments, with the greatest changes elicited upon inoculation with V. sp. F10. We suggest that these differentially regulated genes play important roles in cuticle integrity, the innate immune response, and general stress responses, and that their expression may enable E. affinis to recognize and regulate symbiotic vibrios. We further report that V. sp. F10 culturability is specifically altered upon colonization of E. affinis. These findings suggest that rather than acting as passive environmental vectors, copepods discriminately interact with vibrios, which may ultimately impact the abundance and activity of copepod-associated bacteria.
  • Thesis
    Interactions between calanoid copepod hosts and their associated microbiota
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2015-02) Almada, Amalia A.
    Copepods are highly abundant environmental reservoirs of many bacterial pathogens. This thesis investigates whether copepod physiology influences the abundance and community structure of its microbiome. To this end, we first examined the ability of the oceanic copepod Calanus finmarchicus to transcriptionally respond to mild stressors and demonstrated that heat shock proteins (Hsps) are a conserved element of the copepod’s regulation of stressful conditions and diapause. We then investigated the transcriptomic response of an estuarine copepod Eurytemora affinis to two distinct Vibrio species, a free-living (V. ordalii 12B09) and a zooplankton specialist (V. sp. F10 9ZB36), and found that E. affinis distinctly responds to colonizing Vibrios. Finally, we probed how specifically and predictably bacterial communities assemble on C. finmarchicus. Our findings suggest that C. finmarchicus has a predictable “core microbiome” that persists throughout the host’s entrance into diapause. Furthermore, the structure of the copepod microbiome may be driven by a combination of the copepod’s feeding history, body size, and bacterial interactions. This thesis work highlights the role of copepods as dynamic reservoirs of diverse microbial communities and implicates copepod host physiology as an important contributor to the activity, abundance, and community structure of its often pathogenic microbiota.