Gene Expression in Proliferating Cells of the Dinoflagellate Alexandrium catenella (Dinophyceae)

Abstract

Understanding the conditions leading to harmful algal blooms, especially those produced by toxic dinoflagellate species, is important for environmental and health safety. In addition to investigations into the environmental conditions necessary for the formation of toxic blooms, we postulate that investigating gene expression in proliferating cells is essential for understanding bloom dynamics. Expressed sequence tags were produced from cultured cells of the toxic dinoflagellate Alexandrium catenella sampled during the initiation phase of growth using Sanger's method and by 454 pyrosequencing. A significant proportion of identified genes (ca. 25%) represented enzymes and proteins that participate in a variety of cellular regulatory mechanisms that may characterize proliferating cells, e.g., control of the cell cycle and division, regulation of transcription, translation and posttranslational protein modifications, signaling, intracellular trafficking, and transport. All of the several genes selected for gene expression assays due to their involvement in metabolism and the cell cycle were overexpressed during exponential growth. These data will be useful for investigating the mechanisms underlying growth and toxin production in toxic Alexandrium species and for studying and monitoring the development of toxic blooms.

Current Knowledge and Recent Advances in Marine Dinoflagellate Transcriptomic Research

“…In the presence of bacteria, the SAM-S and SAHH genes were among the downregulated genes. These genes have been previously reported to be associated with toxin production in dinoflagellates [30,74]. Thus, it seems possible that bacteria may influence toxin production level through these genes.…”

“…Transcription factors in dinoflagellates are less abundant in comparison to those present in other protists such as Plasmodium, and it has been suggested that this low abundance may be a genomic signature for dinoflagellates [28]. Numerous novel dinoflagellate genes that are involved in gene regulation at the transcriptional and post-transcriptional level have been discovered in the Alexandrium catenella transcriptome, including homologs for a forkhead box protein (FOXL1), multiprotein bridging factor type 1 (MBF1), RAP2.4 and two identified TATA box-binding protein interacting proteins (TBP-IP; RuvB-like 1 and 2) [30]. Interestingly, the genome sequence of Symbiodinium kawagutii possesses a TATA-box binding protein (TBP)-like factor instead of TBP, which has high affinity toward the TTTT promoter motif [15].…”

“…The role of PKSs in toxin production of dinoflagellates needs to be further investigated, as several PKS genes found in dinoflagellates may potentially function as fatty acid synthases (FAS) [72,73]. In A. catenella strain ACT03, expression levels of two genes, S-adenosyl-homocysteine hydrolase (SAHH) and S-adenosylmethionine synthetase (SAM-S), which are involved in methylation and cell cycle progression, were speculated to correlate with toxin expression in A. catenella [30]. This finding is further supported by qPCR data of an A. catenella strain CAWD44 showing that the expression of SAHH and SAM-S-methionine aminopeptidase (MAP) genes were upregulated during saxitoxin production and the G2-M phase of the cell cycle [74].…”

Growth- and nutrient-dependent gene expression in the toxigenic marine dinoflagellate Alexandrium minutum

“…Both regulation of mRNA abundances (Hosoi-Tanabe et al, 2005;Okamoto and Hastings, 2003;Taroncher-Oldenburg and Anderson, 2000;Toulza et al, 2010) and a high prevalence of translational regulation Lidie, 2007;Rossini et al, 2003) have been reported in dinoflagellates. The discovery of spliced-leader transsplicing (Lidie and Van Dolah, 2007;Slamovits and Keeling, 2008;Zhang et al, 2007) and of single-domain transcripts apparently derived from multi-domain genes led to the suggestion of trypanosome-like mechanisms of spliced-leader-associated constitutive translational gene regulation in dinoflagellates (Monroe and Van Dolah, 2008).…”

Dinoflagellates: Ecological Approaches and Spatial Distributions in Malaysia Waters

“…Dinoflagellates are important producer of the marine environment because of the large amount of carbon fixed from the photosynthesis [5,6]. These microorganisms are characterized by their reliance towards light intensity since they are exposed to UV light at the pelagic area and rich in chlorophyll contents, which explained the significant of photosynthesis [7].…”