Harmful algal blooms (HABs), exacerbated by climate change and environmental disturbances, pose global challenges due to marine toxin contamination, particularly diarrhetic shellfish toxins (DSTs). DSTs are prevalent marine toxins, and understanding their synthesis is vital for managing fisheries and mitigating environmental triggers. This study delves into the synthesis mechanisms of DSTs in Prorocentrum arenarium and Prorocentrum lima, which vary in toxin types and concentrations. We conducted a comprehensive comparative transcriptomic analysis to identify potential toxin-related genes, focusing on polyketide synthases (PKSs) and fatty acid synthases (FASs). Our research predicted 96 PKSs and 91 FASs genes, with a detailed examination of their sequences to elucidate dinophysistoxins (DTXs) synthesis. Additionally, we analyzed differential gene expression of PKSs in P. arenarium under nitrogen and phosphorus-limited conditions, revealing a correlation between specific PKSs gene expression patterns and okadaic acid (OA) content variations. These findings suggest a potential role of the fatty acid biosynthesis pathway in DSTs synthesis. While not completely uncovering the biosynthetic pathway of DSTs, our study offers crucial insights and genomic resources for future research on dinoflagellate toxin production mechanisms.
The construction of artificial reefs (ARs) is an effective way to restore habitats and increase and breed fishery resources in marine ranches. However, studies on the impacts of ARs on the structure, function, and assembly patterns of the bacterial community (BC), which is important in biogeochemical cycles, are lacking. The compositions, diversities, assembly patterns, predicted functions, and key environmental factors of the attached and free-living microbial communities in five-year ARs (O-ARs) and one-year ARs (N-ARs) in Fangchenggang, China, were analyzed via 16S rRNA gene sequencing. Proteobacteria was the dominant taxon in all the samples, with an average relative abundance of 44.48%, followed by Bacteroidetes (17.42%) and Cyanobacteria (15.19%). The composition of bacterial phyla was similar between O-ARs and N-ARs, but the relative abundance of Cyanobacteria was greater in the water column (38.56%) than on the AR surface (mean of 7.40%). The results revealed that the Shannon‒Wiener diversity indices were 5.64 and 5.45 for O-ARs and N-ARs, respectively. Principal coordinate analysis (PCoA) revealed different distributions of O-ARs and N-ARs in the microbial community. Additionally, network analysis revealed that the bacterial community was more complex and stable in O-ARs than in N-ARs, indicating that the 5-year AR presented a more diverse and stable microbial community overall. The KEGG database was used to predict that nitrogen metabolism, carbon metabolism, and membrane transport were the dominant microbial functions, accounting for 29.93% of the total functional abundances. The results of the neutral community model revealed that stochastic processes (67.2%) dominated the assembly of BCs. Interestingly, deterministic processes may be increasingly important in community aggregation over time. Moreover, a null model revealed that dispersal limitation was the most important process among the stochastic processes, accounting for 57.14% of the total. In addition, redundancy analysis (RDA) revealed that hydrological factors obviously impacted the structure and function of the microbial community. Our results showed that the construction of ARs slightly promotes local diversities in the structure and function of the microbial community, indicating it requires a longer time to enhance the diversity of the microbial community on artificial reefs. • Artificial reefs facilitate the diversity and functions of the microbial community • Stochastic processes dominate the assembly of the microbial community in artificial reefs • Nitrogen and carbon metabolism dominate microbial functions in artificial reefs
Abstract Pladienolide, herboxidiene and spliceostatin have been identified as splicing modulators that target SF3B1 in the SF3b subcomplex. Here we report that PHF5A, another component of this subcomplex, is also targeted by these compounds. Mutations in PHF5A-Y36, SF3B1-K1071, SF3B1-R1074 and SF3B1-V1078 confer resistance to these modulators, suggesting a common interaction site. RNA-seq analysis reveals that PHF5A-Y36C has minimal effect on basal splicing but inhibits the global action of splicing modulators. Moreover, PHF5A-Y36C alters splicing modulator-induced intron-retention/exon-skipping profile, which correlates with the differential GC content between adjacent introns and exons. We determine the crystal structure of human PHF5A demonstrating that Y36 is located on a highly conserved surface. Analysis of the cryo-EM spliceosome B act complex shows that the resistance mutations cluster in a pocket surrounding the branch point adenosine, suggesting a competitive mode of action. Collectively, we propose that PHF5A–SF3B1 forms a central node for binding to these splicing modulators.
A harmful benthic Prorocentrum concavum bloom was recorded in August 2018 in Xincun Bay, China, which is the location of a national seagrass nature reserve. Annual ecological surveys have been conducted to study the population dynamics of P. concavum in the benthic community and water column. Seasonal variations in benthic P. concavum abundance were found and the abundances on seagrass and macroalgae in the wet season were 2.5 and 2.82 times higher, respectively, than those in the dry season, although the differences were not statistically significant. The abundance of P. concavum in the water column differed significantly between seasons. The maximum abundances of benthic and planktonic P. concavum were (1.7 ± 0.59) × 106 cells (100 cm2)−1 on Thalassia hemperichii in July and 2.0 × 104 ± 4.7 × 103 cells L−1 in June, respectively. High spatial heterogeneity in P. concavum abundance was observed among five sampling sites. Abundances were significantly higher in seagrass beds than those in macroalgae beds, mangroves, and coral reefs. The abundance of P. concavum at site A (in a seagrass bed and close to a cage-culture area) was 5.6 times higher than that at site D (seagrass bed and distant from the cage-culture area). Planktonic P. concavum showed a similar spatial distribution and presented a maximum density at site A. Moreover, the abundance of benthic P. concavum also showed heterogeneity on host substrates, and the abundance on T. hemperichii was significantly higher than that on sediment. Based on a Spearman’s test, temperature, dissolved organic phosphorus, and dissolved organic nitrogen were the three important factors driving the spatiotemporal distribution of benthic P. concavum in Xincun Bay. Planktonic P. concavum were derived from cells on the substrates and were influenced by concentrations of dissolved oxygen. In conclusion, seagrass beds may be a reservoir of harmful benthic algal blooms in Xincun Bay and the dense cage-culture area provides sufficient organic nutrients for the growth and reproduction of benthic dinoflagellates.
RIP1 has emerged as a master regulator in TNFα signaling that controls two distinct cellular fates: cell survival versus programmed cell death. Because the default response of most cells to TNFα is NF-κB–mediated inflammation and survival, a specific mechanism must exist to control the divergence of signaling outcome. Here, we identify HSPA13 as a transcription-independent checkpoint to modulate the role of RIP1 in TNFα signaling. Through specific binding to TNFR1 and RIP1, HSPA13 enhances TNFα-induced recruitment of RIP1 to TNFR1, and consequently promotes downstream NF-κB transcriptional responses. Meanwhile, HSPA13 attenuates the participation of RIP1 in cytosolic complex II and prevents cells from programmed death. Loss of HSPA13 shifts the transition of RIP1 from complex I to complex II and promotes both apoptosis and necroptosis. Thus, our study provides compelling evidence for the cellular protective function of HSPA13 in fine-tuning TNFα responses.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
