Genomic Insights into Processes Driving the Infection of Alexandrium tamarense by the Parasitoid Amoebophrya sp

Abstract

The regulatory circuits during infection of dinoflagellates by their parasites are largely unknown on the molecular level. Here we provide molecular insights into these infection dynamics. Alexandrium tamarense is one of the most prominent harmful algal bloom dinoflagellates. Its pathogen, the dinoflagellate parasitoid Amoebophrya sp., has been observed to infect and control the blooms of this species. We generated a data set of transcripts from three time points (0, 6, and 96 h) during the infection of this parasite-host system. Assembly of all transcript data from the parasitoid (>900,000 reads/313 Mbp with 454/Roche next-generation sequencing [NGS]) yielded 14,455 contigs, to which we mapped the raw transcript reads of each time point of the infection cycle. We show that particular surface lectins are expressed at the beginning of the infection cycle which likely mediate the attachment to the host cell. In a later phase, signal transduction-related genes together with transmembrane transport and cytoskeleton proteins point to a high integration of processes involved in host recognition, adhesion, and invasion. At the final maturation stage, cell division-and proliferation-related genes were highly expressed, reflecting the fast cell growth and nuclear division of the parasitoid. Our molecular insights into dinoflagellate parasitoid interactions point to general mechanisms also known from other eukaryotic parasites, especially from the Alveolata. These similarities indicate the presence of fundamental processes of parasitoid infection that have remained stable throughout evolution within different phyla.

Transcriptomic profiling of Alexandrium fundyense during physical interaction with or exposure to chemical signals from the parasite Amoebophrya

“…The Amoebophrya (AT5.2) parasite strain [the term parasitoid is also used (Lu et al . )] was isolated from Alexandrium cells sampled from the Gulf of Maine, USA (Chambouvet et al . ), and was used to infect the Alexandrium fundyense strain [formerly described as A. tamarense (John et al .…”

“…The Amoebophrya (AT5.2) parasite strain [the term parasitoid is also used (Lu et al 2014)] was isolated from Alexandrium cells sampled from the Gulf of Maine, USA (Chambouvet et al 2011), and was used to infect the Alexandrium fundyense strain [formerly described as A. tamarense ] isolated from the North Sea coast of Scotland (Alex5; RCC3037) ). To understand the host-parasite mechanisms, we needed a strain, which can be reliably infected with high rates.…”

“…Amoebophrya is a model parasitic organism that can be cocultured with its host, Alexandrium, in the laboratory with an infective cycle of approximately 4 days (Lu et al . ). Infection by Amoebophrya is initiated by penetration of the parasitic dinospores into the host cells (Cachon ; Miller et al .…”

“…Together with grazing by microzooplankton, parasite infection is an important top-down control mechanism for bloom-forming dinoflagellates (Montagnes et al 2008). Amoebophrya is a model parasitic organism that can be cocultured with its host, Alexandrium, in the laboratory with an infective cycle of approximately 4 days (Lu et al 2014). Infection by Amoebophrya is initiated by penetration of the parasitic dinospores into the host cells (Cachon 1964;Miller et al 2012).…”

Trait changes induced by species interactions in two phenotypically distinct strains of a marine dinoflagellate

“…Protocol details are described by Lu et al (2014). RNA quality and integrity were verified with a RNA Nano-Chip Assay on a 2100 Bioanalyzer device (Agilent Technologies, Santa Clara, CA, USA).…”