P. lima, a source of polyketide compounds, including okadaic acid (OA), dinophysistoxin (DTX), and their analogs, are implicated in diarrhetic shellfish poisoning (DSP). Insight into the molecular mechanism of DSP toxin biosynthesis is vital for understanding the environmental factors governing toxin production and facilitating improved monitoring of marine ecosystems. Polyketide synthases (PKS) are the enzymes primarily responsible for the production of polyketides. However, no gene has been positively attributed to the synthesis of DSP toxins. Using Trinity, we assembled a transcriptome from the 94,730,858 Illumina RNA-Seq reads, which resulted in 147,527 unigenes, showing an average sequence length of 1035 nucleotides. Through bioinformatics analysis, we discovered 210 unigenes encoding single-domain polyketide synthases (PKS) with sequence similarity to type I PKSs, as previously observed in other dinoflagellate species. Of note, fifteen transcripts encoding multi-domain polyketide synthases (typical type I modules) and five transcripts encoding hybrid nonribosomal peptide synthetase/polyketide synthase systems were identified. 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, alongside other recent transcriptome analyses, reinforces the growing consensus that dinoflagellates potentially use a blend of Type I multi-domain and single-domain PKS proteins, in a way that remains unclear, for polyketide biosynthesis. selleck Future research on the intricate toxin production mechanisms in this dinoflagellate will benefit significantly from the valuable genomic resources our study provides.

Eleven species of perkinsozoan parasitoids infecting dinoflagellates are now recognized, representing an increase compared to the figures two decades ago. The current knowledge base on the autecology of perkinsozoan parasitoids of dinoflagellates is predominantly derived from studies focusing on only one or two species, thereby impeding direct comparisons of their biological traits and hindering evaluation of their possible application as biocontrol agents for managing harmful dinoflagellate blooms in the field. Investigating five perkinsozoan parasitoids, this study determined the total generation time, zoospore count per sporangium, zoospore dimensions, swimming speeds, infection rates, zoospore survival rates, host ranges, and their respective susceptibilities. Parviluciferaceae encompassed four species: Dinovorax pyriformis, Tuberlatum coatsi, Parvilucifera infectans, and P. multicavata. Pararosarium dinoexitiosum, the sole species in the Pararosariidae family, also used Alexandrium pacificum, the common host dinoflagellate. Five perkinsozoan parasitoid species exhibited discernible biological differences, leading to the conclusion of varied fitness levels within this host species. These results offer valuable background data crucial for understanding the effects of parasitoids on natural host populations, and for developing numerical models which consider host-parasitoid interactions within field-based biocontrol schemes.

Marine microbial communities likely utilize extracellular vesicles (EVs) as a significant transport and communication mechanism. The task of isolating and characterizing axenic cultures of microbial eukaryotes presents an ongoing technological challenge. Our investigation successfully isolated extracellular vesicles (EVs) from a near-axenic culture of the harmful dinoflagellate Alexandrium minutum for the first time. Using Cryo TEM (Cryogenic Transmission Electron Microscopy), pictures of the isolated vesicles were taken. EVs were grouped into five primary categories based on their morphotype: rounded, rounded electron-dense, electron-dense lumen, double, and irregular. The size of each vesicle was determined, leading to an average diameter of 0.36 micrometers. Considering the established role of extracellular vesicles (EVs) in prokaryotic toxicity mechanisms, this descriptive study serves as a preliminary investigation into the potential contribution of EVs to dinoflagellate toxicity.

The persistent problem of Karenia brevis blooms, or red tide, impacts the coastal areas of the Gulf of Mexico. These blossoming creations have the potential to cause a substantial amount of damage to the health of humans and animals, and also to local economic systems. Consequently, the meticulous tracking and discovery of K. brevis blooms in all stages of development and at various cell densities are indispensable for public well-being. selleck Size resolution limits, concentration range limitations, restricted spatial and temporal profiling, and/or the processing of small sample volumes are all inherent drawbacks of the present K. brevis monitoring methods. A novel monitoring method, employing an autonomous digital holographic imaging microscope (AUTOHOLO), is presented here. This method surpasses previous limitations and enables in situ characterization of K. brevis concentrations. Employing the AUTOHOLO, in-situ measurements of field conditions were made in the Gulf of Mexico's coastal waters during the 2020-21 winter's intense K. brevis bloom. Using benchtop holographic imaging and flow cytometry, the laboratory analyzed water samples from surface and subsurface areas, collected during these field studies, for validation. A convolutional neural network's training enabled the automatic classification of K. brevis at all concentration levels. A 90% accurate network, validated via manual counts and flow cytometry, was established across diverse datasets exhibiting varying K. brevis concentrations. Demonstrating the value of combining the AUTOHOLO with a towing system, the potential to characterize particle abundance over broad distances was highlighted, suggesting the possibility of characterizing the spatial distribution of K. brevis blooms. Future AUTOHOLO implementation, combining with existing HAB monitoring networks, can improve K. brevis detection capabilities in water bodies all over the world.

The link between seaweed population responses to environmental stressors and their habitat regimes is significant. Two Ulva prolifera strains, Korean and Chinese, were studied to understand their growth and physiological reactions in response to a combination 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). At 40 psu of salinity, both strains exhibited the lowest growth rates, uninfluenced by variations in temperature or nutrient levels. Under the influence of a 20°C temperature and low nutrient conditions, the carbon-nitrogen (C:N) ratio of the Chinese strain increased by 311%, while its growth rate surged by 211% at 20 psu salinity compared to a salinity of 30 psu. The elevated nutrient levels contributed to a lower CN ratio in both strains, as tissue nitrogen content increased. At a salinity of 20°C, simultaneous high nutrient levels led to increased soluble protein and pigment content, and also accelerated photosynthetic and growth rates in both strains. A notable decrease in growth rates and carbon-to-nitrogen ratios of both strains was observed in the presence of increased salinity levels within a temperature range of below 20 degrees Celsius and high nutrient concentrations. selleck The pigment, soluble protein, and tissue N demonstrated an opposite trend to the growth rate at every condition. Furthermore, a 25-degree Celsius temperature inhibited the development of both strains, irrespective of the nutrient content. The Chinese strain's tissue N and pigment content augmentation was contingent on low nutrient availability, occurring only at a temperature of 25°C. Elevated nutrient levels at 25°C fostered a rise in tissue nitrogen and pigment concentrations in both strains across all salinity levels, contrasting with the 20°C and high nutrient treatment. High nutrient levels and a 25°C temperature significantly reduced the growth rate of the Chinese strain, particularly at 30 psu and 40 psu salinity, in contrast to the growth rate seen at 20°C with low nutrient levels and the same salinity. These findings indicate that the Chinese strain's Ulva blooms experienced a more substantial impact from hypo-salinity conditions than those of the Korean strain. U. prolifera strains demonstrated enhanced salinity tolerance in response to elevated nutrient levels. U. prolifera blooms, particularly those of the Chinese strain, will experience a decrease in numbers at extreme salinity levels.

Harmful algal blooms (HABs) are responsible for widespread fish mortality globally. However, some commercially-sourced fish are perfectly safe to eat. Fish that are safe for consumption present significant differences from the fish that are routinely washed ashore. Studies conducted previously demonstrate that consumers largely misunderstand the edibility differences between various fish, with the mistaken belief that particular fish are unsafe and unhealthy serving as a prevalent misconception. Consumer reactions to information about seafood health during algal blooms, and the subsequent shifts in their consumption habits, have seen little in the way of thorough research to date. A survey is implemented to provide respondents with the necessary information on the health and safety of commercially caught seafood, specifically red grouper, during a harmful algal bloom (HAB). In the depths of the ocean, a large and popular deep-sea fish is frequently seen. The results show that respondents informed with this data expressed a 34 percentage point higher likelihood of stating their willingness to consume red grouper during a bloom, as opposed to those who were not given this extra information. Historical data indicates that long-term community engagement initiatives are arguably more effective than sales campaigns concentrated at the point of purchase. 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.