Dynamic causes contribute to the increasing trend of red tides in the east China sea during 2020-2022.

Red tide is a marine phenomenon caused by the excessive growth of microscopic algae in the ocean. This study aims to analyze the development trends of red tides in the past 20 years and the dynamic external causes that induce red tides based on existing satellite remote sensing and numerical simulation data. And the changes in dominant species of red tides in different seasons are analyzed. The results show significant temperature fluctuations within the week before the red tide occurs, with an average increase of 1.42 °C. In contrast, the change in salinity is relatively small. Meanwhile, ocean fronts are areas in the ocean where different water masses meet and form boundaries. The average strength of ocean fronts increased by 3.7%, indicating enhanced ocean mixing over a short period of time. Under the combined influence of these factors, the probability of a red tide outbreak in the East China Sea increases rapidly. Therefore, this study has important reference value for further research on the causes of red tides and their response to ocean dynamic changes.

Platycodonis Radix Alleviates LPS-Induced Lung Inflammation through Modulation of TRPA1 Channels.

Platycodonis Radix (PR), a widely consumed herbal food, and its bioactive constituents, platycodins, have therapeutic potential for lung inflammation. Transient Receptor Potential Ankyrin 1 (TRPA1), which is essential for the control of inflammation, may be involved in the development of inflammation in the lungs. The aim of this study was to determine the TRPA1-targeted effects of PR against pulmonary inflammation and to investigate the affinity of PR constituents for TRPA1 and their potential mechanisms of action. Using a C57BL/6J mouse lipopolysaccharides (LPS) intratracheal instillation pneumonia model and advanced analytical techniques (UPLC-Q-TOF-MS/MS, molecular docking, immuno-fluorescence), five platycodins were isolated from PR, and the interaction between these platycodins and hTRPA1 was verified. Additionally, we analyzed the impact of platycodins on LPS-induced TRPA1 expression and calcium influx in BEAS-2B cells. The results indicated that PR treatment significantly reduced the severity of LPS-triggered inflammation in the mouse model. Interestingly, there was a mild increase in the expression of TRPA1 caused by PR in healthy mice. Among five isolated platycodins identified in the PR extract, Platycodin D3 (PD3) showed the highest affinity for hTRPA1. The interaction between platycodins and TRPA1 was verified through molecular docking methods, highlighting the significance of the S5-S6 pore-forming loop in TRPA1 and the unique structural attributes of platycodins. Furthermore, PD3 significantly reduced LPS-induced TRPA1 expression and calcium ion influx in BEAS-2B cells, substantiating its own role as an effective TRPA1 modulator. In conclusion, PR and platycodins, especially PD3, show promise as potential lung inflammation therapeutics. Further research should explore the precise mechanisms by which platycodins modulate TRPA1 and their broader therapeutic potential.

Phylogenomics of five Pseudanabaena cyanophages and evolutionary traces of horizontal gene transfer.

BACKGROUND: Along with the fast development and urbanization in developing countries, the waterbodies aside the growing cities become heavily polluted and highly eutrophic, thus leading to the seasonal outbreak of cyanobacterial bloom. Systematic isolation and characterization of freshwater cyanophages might provide a biological solution to control the awful blooms. However, genomic sequences and related investigations on the freshwater cyanophages remain very limited to date. RESULTS: Following our recently reported five cyanophages Pam1~Pam5 from Lake Chaohu in China, here we isolated another five cyanophages, termed Pan1~Pan5, which infect the cyanobacterium Pseudanabaena sp. Chao 1811. Whole-genome sequencing showed that they all contain a double-stranded DNA genome of 37.2 to 72.0 kb in length, with less than half of the putative open reading frames annotated with known functions. Remarkably, the siphophage Pan1 encodes an auxiliary metabolic gene phoH and constitutes, together with the host, a complete queuosine modification pathway. Proteomic analyses revealed that although Pan1~Pan5 are distinct from each other in evolution, Pan1 and Pan3 are somewhat similar to our previously identified cyanophages Pam3 and Pam1 at the genomic level, respectively. Moreover, phylogenetic analyses suggested that Pan1 resembles the α-proteobacterial phage vB_DshS-R5C, revealing direct evidence for phage-mediated horizontal gene transfer between cyanobacteria and α-proteobacteria. CONCLUSION: In addition to the previous reports of Pam1~Pam5, the present findings on Pan1~Pan5 largely enrich the library of reference freshwater cyanophages. The abundant genomic information provides a pool to identify novel genes and proteins of unknown function. Moreover, we found for the first time the evolutionary traces in the cyanophage that horizontal gene transfer might occur at the level of not only inter-species, but even inter-phylum. It indicates that the bacteriophage or cyanophage could be developed as a powerful tool for gene manipulation among various species or phyla.

Fine structure and assembly pattern of a minimal myophage Pam3.

The myophage possesses a contractile tail that penetrates its host cell envelope. Except for investigations on the bacteriophage T4 with a rather complicated structure, the assembly pattern and tail contraction mechanism of myophage remain largely unknown. Here, we present the fine structure of a freshwater Myoviridae cyanophage Pam3, which has an icosahedral capsid of ~680 Å in diameter, connected via a three-section neck to an 840-Å-long contractile tail, ending with a three-module baseplate composed of only six protein components. This simplified baseplate consists of a central hub-spike surrounded by six wedge heterotriplexes, to which twelve tail fibers are covalently attached via disulfide bonds in alternating upward and downward configurations. In vitro reduction assays revealed a putative redox-dependent mechanism of baseplate assembly and tail sheath contraction. These findings establish a minimal myophage that might become a user-friendly chassis phage in synthetic biology.

Structural Insights into the Chaperone-Assisted Assembly of a Simplified Tail Fiber of the Myocyanophage Pam3.

At the first step of phage infection, the receptor-binding proteins (RBPs) such as tail fibers are responsible for recognizing specific host surface receptors. The proper folding and assembly of tail fibers usually requires a chaperone encoded by the phage genome. Despite extensive studies on phage structures, the molecular mechanism of phage tail fiber assembly remains largely unknown. Here, using a minimal myocyanophage, termed Pam3, isolated from Lake Chaohu, we demonstrate that the chaperone gp25 forms a stable complex with the tail fiber gp24 at a stoichiometry of 3:3. The 3.1-Å cryo-electron microscopy structure of this complex revealed an elongated structure with the gp25 trimer embracing the distal moieties of gp24 trimer at the center. Each gp24 subunit consists of three domains: the N-terminal α-helical domain required for docking to the baseplate, the tumor necrosis factor (TNF)-like and glycine-rich domains responsible for recognizing the host receptor. Each gp25 subunit consists of two domains: a non-conserved N-terminal ß-sandwich domain that binds to the TNF-like and glycine-rich domains of the fiber, and a C-terminal α-helical domain that mediates trimerization/assembly of the fiber. Structural analysis enabled us to propose the assembly mechanism of phage tail fibers, in which the chaperone first protects the intertwined and repetitive distal moiety of each fiber subunit, further ensures the proper folding of these highly plastic structural elements, and eventually enables the formation of the trimeric fiber. These findings provide the structural basis for the design and engineering of phage fibers for biotechnological applications.