The phenomenon of diarrhetic shellfish poisoning (DSP) stems from polyketide compounds, such as okadaic acid (OA), dinophysistoxin (DTX), and their structural analogs, specifically those produced by P. lima. For better monitoring of marine ecosystems and to understand the environmental factors influencing DSP toxin biosynthesis, an understanding of the molecular mechanisms involved is paramount. Polyketides' biosynthesis is often catalyzed by the enzymatic machinery of polyketide synthases, or PKS. Nevertheless, no gene has been definitively linked to the production of DSP toxins. From 94,730,858 Illumina RNA-Seq reads, a transcriptome was constructed using Trinity, comprising 147,527 unigenes, each with an average nucleotide sequence length of 1035. Using bioinformatics approaches, our study identified 210 unigenes coding for single-domain polyketide synthases (PKS) that share sequence similarities with type I PKSs, consistent with reports from other dinoflagellate research. The analysis further revealed fifteen transcripts encoding multi-domain PKS (forming the canonical type I PKS modules) and five transcripts encoding hybrid nonribosomal peptide synthetase/polyketide synthase systems. Comparative analysis of transcriptomes, coupled with differential expression profiling, revealed 16 PKS genes upregulated in phosphorus-limited cultures, a phenomenon related to upregulation of toxin production. This study, in congruence with other recent transcriptome analyses, adds to the growing understanding that dinoflagellates could potentially utilize a combination of Type I multi-domain and single-domain PKS proteins, in a currently undefined manner, for the synthesis of polyketides. Cloning and Expression Understanding the complex toxin production mechanisms in this dinoflagellate will be aided by the genomic resource our study provides for future research endeavors.
The last two decades have witnessed an increase in the known perkinsozoan parasitoid species infecting dinoflagellates, now reaching eleven. Current understanding of perkinsozoan parasitoid autecology concerning dinoflagellates is largely derived from studies of a small number of species, making comparative analyses of their biological characteristics challenging, and correspondingly restricting assessment of their potential as biological control agents for combating harmful dinoflagellate blooms. This investigation explored the total time taken for generation, the number of zoospores produced in each sporangium, the dimension of zoospores, the speed of zoospore movement, the prevalence of parasites, the survival and success rate of zoospores, and the spectrum of hosts and their vulnerability to five different perkinsozoan parasitoids. Dinovorax pyriformis, Tuberlatum coatsi, Parvilucifera infectans, and P. multicavata, four species belonging to the Parviluciferaceae family, along with Pararosarium dinoexitiosum, a member of the Pararosariidae family, all utilized the dinoflagellate Alexandrium pacificum as a shared host. The five perkinsozoan parasitoid species showcased noticeable variations in their biological traits, suggesting that their fitness for the same host organism varied. The implications of these outcomes are significant for understanding parasitoid effects on natural host populations, and for the development of numerical models incorporating host-parasitoid systems and field-based biocontrol strategies.
Likely, extracellular vesicles (EVs) are an important method of transport and communication in the complex marine microbial community. Successfully isolating and characterizing microbial eukaryotes from axenic cultures is a technological obstacle that has yet to be overcome entirely. We now report, for the first time, the isolation of EVs from a virtually axenic culture of the toxic species Alexandrium minutum. To obtain images of the isolated vesicles, Cryo TEM (Cryogenic Transmission Electron Microscopy) was utilized. Morphological analysis clustered the EVs into five broad groups—rounded, electron-dense rounded, lumen electron-dense, double-layered, and irregular. A diameter measurement for each vesicle resulted in an average size of 0.36 micrometers. Because prokaryotic toxicity has been shown to involve extracellular vesicles (EVs), this descriptive work intends to be the initial study into the potential role of EVs in the toxicity processes seen in dinoflagellates.
In the coastal Gulf of Mexico, the cyclical occurrence of Karenia brevis blooms, also known as red tide, remains a significant concern. The capability of these flowers to inflict substantial harm extends to both human and animal health, and the surrounding local economies. Therefore, it is vital to track and pinpoint Karenia brevis blooms throughout their entire lifecycle and across a spectrum of cell concentrations, thereby protecting the public. this website Current monitoring of K. brevis is hampered by limitations in size resolution and concentration ranges, restricted spatial and temporal profiling capabilities, and/or limitations when processing small sample volumes. Here, we introduce a novel monitoring method. The autonomous digital holographic imaging microscope (AUTOHOLO) is employed to overcome limitations and enables in situ K. brevis concentration determination. The active K. brevis bloom in the coastal Gulf of Mexico, during the 2020-2021 winter, was the subject of in-situ field measurements carried out using the AUTOHOLO. Using benchtop holographic imaging and flow cytometry, the laboratory analyzed water samples from surface and subsurface areas, collected during these field studies, for validation. To achieve automated classification of K. brevis across all concentration ranges, a convolutional neural network underwent training. A 90% accurate network, validated via manual counts and flow cytometry, was established across diverse datasets exhibiting varying K. brevis concentrations. The AUTOHOLO, when integrated with a towing system, was shown to be effective in characterizing particle abundance across significant distances, a technique that could aid in the characterization of K. brevis spatial distribution during blooms. Future AUTOHOLO implementation, combining with existing HAB monitoring networks, can improve K. brevis detection capabilities in water bodies all over the world.
The specific way in which seaweeds react to environmental stressors depends on their population and the conditions of their habitat regime. Two strains of Ulva prolifera (Korean and Chinese) were analyzed for their growth and physiological responses under varying conditions of temperature (20°C and 25°C), nutrient concentrations (low: 50 µM nitrate and 5 µM phosphate; high: 500 µM nitrate and 50 µM phosphate), and salinity (20, 30, and 40 parts per thousand). Regardless of temperature and nutrient levels, the lowest growth rates for both strains were recorded at a salinity of 40 psu. The Chinese strain's carbon-nitrogen (C:N) ratio saw a 311% improvement and its growth rate a 211% boost at 20°C, low nutrient conditions, and a 20 psu salinity compared to 30 psu salinity. High nutrients were associated with a decrease in the CN ratio for both strains as their tissue nitrogen content increased. Simultaneously, elevated nutrient levels led to an increase in soluble proteins and pigments, as well as enhanced photosynthetic and growth rates in both strains cultivated at the same salinity levels of 20°C. At temperatures below 20 degrees Celsius and in the presence of abundant nutrients, both strains exhibited a considerable reduction in growth rates and carbon-to-nitrogen ratios as salinity increased. mid-regional proadrenomedullin The pigment, soluble protein, and tissue N demonstrated an opposite trend to the growth rate at every condition. Consequently, the temperature of 25°C prevented the growth of both strains, irrespective of the available nutrients. 25°C facilitated increases in tissue N and pigment content within the Chinese strain, exclusively at the lower end of nutrient availability. Higher tissue nitrogen and pigment contents were observed in both strains under high nutrient levels and a 25°C temperature across all salinity conditions, in contrast to the 20°C and high nutrient treatments. The growth rate of the Chinese strain was negatively affected by a 25°C temperature combined with abundant nutrients at both 30 psu and 40 psu salinities, demonstrating a greater decrease compared to growth under 20°C and limited nutrient availability at the same salinities. These results suggest a greater negative effect of hypo-salinity on Ulva blooms cultivated from the Chinese strain, relative to those from the Korean strain. The salinity tolerance of both U. prolifera strains was amplified by elevated nutrient levels. At elevated salinity levels, the number of U. prolifera blooms of the Chinese strain will decrease.
Harmful algal blooms (HABs) inflict significant mortality on fish populations worldwide. Yet, certain commercially-harvested species present no dietary concerns. A considerable divergence exists between fish that are safe for eating and those that are discovered on the coast. Earlier research indicates a consumer deficiency in understanding the distinctions in edibility among fish types, with a common misperception that specific fish are both unhealthy and unsafe forming the prevailing view. Few studies have investigated how disseminating information on seafood health to consumers would impact their consumption patterns during algal blooms. A survey detailing the health and safety of commercially caught seafood, particularly red grouper, during harmful algal blooms (HABs), is implemented to inform respondents. A large, deep-sea fish, particularly popular, is often found in the ocean depths. This information indicates a 34 percentage point greater willingness expressed by those receiving the data to consume red grouper during a bloom than those not given this information. A comprehensive understanding of the available data implies that continuous outreach efforts are likely more effective than promotional campaigns focused solely on immediate sales. The study's findings emphasized the necessity for accurate HAB knowledge and awareness within the context of supporting local economies that rely on seafood harvesting and consumption for their sustenance.