Category: Dinoflagellate genomics

Many dinoflagellate species make toxins in a myriad of different molecular configurations but the underlying chemistry in all cases is presumably via modular synthases, primarily polyketide synthases. In many organisms modular synthases occur as discrete synthetic genes or domains within a gene that act in coordination thus forming a module that produces a particular fragment of a natural product. The modules usually occur in tandem as gene clusters with a syntenic arrangement that is often…

Programmed cell death (PCD) in dinoflagellates has been introduced as a new concept that facilitates the demise of harmful algal blooms. Metacaspases (MCAs) play a role in PCD, but their function in dinoflagellates is unclear. Here, we cloned a novel MCA gene (PmMCA) from the harmful dinoflagellate Prorocentrum minimum and examined its molecular characteristics and gene expression during cell death. The gene was encoded in the nuclear genome with two introns. The putative protein contained 288…

Photosynthesis in cyanobacteria, green algae, and basal land plants is protected against excess reducing pressure on the photosynthetic chain by flavodiiron proteins (FLV) that dissipate photosynthetic electrons by reducing O(2). In these organisms, the genes encoding FLV are always conserved in the form of a pair of two-type isozymes (FLVA and FLVB) that are believed to function in O(2) photo-reduction as a heterodimer. While coral symbionts (dinoflagellates of the family Symbiodiniaceae) are…

Berghia stephanieae (Nudibranchia, Cladobranchia) is a photosymbiotic sea slug that feeds exclusively on sea anemones from the genus Exaiptasia. It then specifically incorporates dinoflagellates belonging to the Symbiodiniaceae obtained from their prey. Here, we present the complete mitochondrial genome sequence of B. stephanieae combining Oxford Nanopore long read and Illumina short-read sequencing data. The mitochondrial genome has a total length of 14,786 bp, it contains the 13…

Cation and anion channelrhodopsins (CCRs and ACRs, respectively) primarily from two algal species, Chlamydomonas reinhardtii and Guillardia theta, have become widely used as optogenetic tools to control cell membrane potential with light. We mined algal and other protist polynucleotide sequencing projects and metagenomic samples to identify 75 channelrhodopsin homologs from four channelrhodopsin families, including one revealed in dinoflagellates in this study. We carried out…

Corals are colonized by symbiotic microorganisms that profoundly influence the animal’s health. One noted symbiont is a single-celled alga (in the dinoflagellate family Symbiodiniaceae), which provides the coral with most of its fixed carbon. Thermal stress increases the production of reactive oxygen species (ROS) by Symbiodiniaceae during photosynthesis. ROS can both damage the algal symbiont’s photosynthetic machinery and inhibit its repair, causing a positive feedback loop for the toxic…

Karenia selliformis is a marine dinoflagellate responsible for fish-kill events. Its presence has been reported along the Tunisian coasts (south-eastern Mediterranean Sea) since the 1990s. In the present study, a quantitative-PCR assay, based on the internal transcribed spacer (ITS) molecular marker, was developed to detect and quantify K. selliformis in environmental bivalve mollusk samples and in seawater samples. The assay was optimized, and its specificity was confirmed using…

Despite the increasing reports of non-cyanobacterial diazotrophs (NCDs) in pelagic waters, only one NCD (GammaA) has been relatively well described, whose genome and physiology are still unclear. Here we present a comprehensive analysis of the biogeography and ecophysiology of a widely distributed NCD, Gamma4. Gamma4 was the most abundant Gammaproteobacterial NCD along transects across the subtropical North Pacific. Using quantitative PCR, Gamma4 was detectable throughout the surface waters of…

Mutualisms where hosts are coupled metabolically to their symbionts often exhibit high partner fidelity. Most reef-building coral species form obligate symbioses with a specific species of photosymbionts, dinoflagellates in the family Symbiodiniaceae, despite needing to acquire symbionts early in their development from environmental sources. Three Caribbean acroporids (Acropora palmata, A. cervicornis, and their F1 hybrid) are sympatric across much of their range, but often occupy different…

An aerobic, Gram-stain-negative, straight or curved rods and dimorphic prosthecate bacterium designated as strain LZ-16-1^(T) was isolated from phycosphere microbiota of routinely laboratory-cultured and highly-toxic marine dinoflagellate Alexandrium catenella LZT09. Strain LZ-16-1^(T) produces active bioflocculanting exopolysaccharides (EPS). Cells were dimorphic with non-motile prostheca, or non-stalked and motile by a single polar flagellum. Growth occurred at 10-40 °C, pH 5-9 and 1-8% (w/v)…