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How can Phycobilisome, the unique light harvesting system in certain algae working highly efficiently: The connection in between structures and functions
No full textAlgae, which are ubiquitous in ecosystems, have evolved a variety of light-harvesting complexes to better adapt to diverse habitats. Phycobilisomes/phycobiliproteins, unique to cyanobacteria, red algae, and certain cryptomonads, compensate for the lack of chlorophyll absorption, allowing algae to capture and efficiently transfer light energy in aquatic environments. With the advancement of microscopy and spectroscopy, the structure and energy transfer processes of increasingly complex phycobilisomes have been elucidated, providing us with a vivid portrait of the dynamic adaptation of their structures to the light environment in which algae thrive: 1) Cyanobacteria living on the surface of the water use short, small phycobilisomes to absorb red-orange light and reduce the damage from blue-violet light via multiple methods; 2) Large red algae inhabiting the depths of the ocean have evolved long and dense phycobilisomes containing phycoerythrin to capture the feeble blue-green light; 3) In far-red light environments such as caves, algae use special allophycocyanin cores to optimally utilize the far-red light; 4) When the environment shifts, algae can adjust the length, composition and density of their rods to better adapt; 5) By carefully designing the position of the pigments, phycobilisomes can transfer light energy to the reaction center with nearly 100% efficiency via three energy transfer processes
Oral administration of anti-lipopolysaccharide factor isoform 3 via the bait microalga for controlling bacterial infection of Atlantic Bay scallop (<i> Argopecten</i> irradians)
No full textIn order to reduce antibiotic application in aquaculture, an antimicrobial peptide anti-lipopolysaccharide factor isoform 3 (ALFPm3) with highly effective inhibitory activity against pathogens was introduced to bay scallop (Argopecten irradians) using bait microalga Tetraselmis subcordiformis as a delivery system. To improve its expression and stability, a fusion of two alfpm3 genes (alfpm3-2) was inserted into an expression vector and transformed into T. subcordiformis chloroplast, followed by in vitro and in vivo functional evaluations of the antimicrobial activities of ALFPm3-2 by minimum inhibitory concentration method and bay scallop breeding experiment, respectively. The results showed that the transformants of T. subcordiformis and the purified ALFPm3-2 had significant inhibitory effects on Vibrio parahaemolyticus and Staphylococcus aureus in vitro, while feeding the transformants reduced the colonization of the two pathogens in bay scallops, which further reduced bay scallops' mortality by 28.67 % as revealed in infection test. Furthermore, daily oral administration of ALFPm3-2 could improve the gut microbial community and reduce the inflammatory response. Combined with changes in immune factors and endotoxin, it indicated that exogenous ALFPm3-2 played antimicrobial and antiinflammatory functions in the guts of bay scallops. Overall, this study provided strong evidence to support the oral administration of antimicrobial peptides via microalgae in aquaculture
Oral administration of anti-lipopolysaccharide factor isoform 3 via the bait microalga for controlling bacterial infection of Atlantic Bay scallop (<i> Argopecten</i> irradians)
No full textIn order to reduce antibiotic application in aquaculture, an antimicrobial peptide anti-lipopolysaccharide factor isoform 3 (ALFPm3) with highly effective inhibitory activity against pathogens was introduced to bay scallop (Argopecten irradians) using bait microalga Tetraselmis subcordiformis as a delivery system. To improve its expression and stability, a fusion of two alfpm3 genes (alfpm3-2) was inserted into an expression vector and transformed into T. subcordiformis chloroplast, followed by in vitro and in vivo functional evaluations of the antimicrobial activities of ALFPm3-2 by minimum inhibitory concentration method and bay scallop breeding experiment, respectively. The results showed that the transformants of T. subcordiformis and the purified ALFPm3-2 had significant inhibitory effects on Vibrio parahaemolyticus and Staphylococcus aureus in vitro, while feeding the transformants reduced the colonization of the two pathogens in bay scallops, which further reduced bay scallops' mortality by 28.67 % as revealed in infection test. Furthermore, daily oral administration of ALFPm3-2 could improve the gut microbial community and reduce the inflammatory response. Combined with changes in immune factors and endotoxin, it indicated that exogenous ALFPm3-2 played antimicrobial and antiinflammatory functions in the guts of bay scallops. Overall, this study provided strong evidence to support the oral administration of antimicrobial peptides via microalgae in aquaculture
Spatio-seasonal variations in functional trait composition and diversity patterns of marine fish communities in coastal waters
No full textDespite the consensus that the distribution of functional traits within a community provides insights into community assembly and maintenance mechanisms, few studies have explored spatio-seasonal variations in the functional patterns of marine fish communities. Seven functional traits within the context of 2 distinct groups-habitat use and trophic niche-were selected to assess functional richness (FRic), functional evenness (FEve), and functional dispersion (FDis) across various spatio-seasonal scales. Community-weighted mean redundancy analysis (CWM-RDA) was used to identify the impact of environmental factors on dominant traits. We found seasonal and spatial variations in dominant traits of the fish community, notably influenced by the latitudinal-depth gradient (from shallower stations in the north to deeper stations in the south), east-west (longitudinal) dynamics, and temperature gradient. Latitude was negatively correlated with the CWM values of most functional trait categories. FRic showed more pronounced seasonal variations than other indices, with higher values observed in autumn. Fish assemblages displayed more similarity in functional traits in winter than in other seasons, with lower FRic, higher FEve, and lower FDis. Overall, our findings illustrate that fish assemblages undergo continuous formation and dissolution across different seasons and zones, resulting in various forms of functional diversity patterns
Impact of summer hypoxia on macrobenthic communities in a semi-enclosed bay: A long-term observation in the North Yellow sea of China
No full textThe O2 content of the global ocean has been declining progressively over the past decades, mainly because of human activities and global warming. Despite this situation, the responses of macrobenthos under hypoxic conditions remain poorly understood. In this study, we conducted a long-term observation (2015-2022) to investigate the intricate impact of summer hypoxia on macrobenthic communities in a semi-enclosed bay of the North Yellow Sea. Comparative analyses revealed higher macrobenthos abundance (1956.8 f 1507.5 ind./m2 vs. 871.8 f 636.9 ind./m2) and biomass (8.2 f 4.1 g/m2 vs. 5.6 f 3.2 g/m2) at hypoxic sites compared to normoxic sites during hypoxic years. Notably, polychaete species demonstrated remarkable adaptability, dominating hypoxic sites, and shaping community structure. The decline in biodiversity underscored the vulnerability and diminished resilience of macrobenthic communities to hypoxic stressors. Stable isotope analysis provided valuable insights into food web structures. The average trophic level of macrobenthos measured 2.84 f 0.70 at hypoxic sites, contrasting with the higher value of 3.14 f 0.74 observed at normoxic sites, indicating the absence of predators at high trophic levels under hypoxic conditions. Moreover, trophic interactions were significantly altered, resulting in a simplified and more vulnerable macrobenthic trophic structure. The findings underscored the importance of comprehensive research to understand the complex responses of macrobenthic communities to hypoxia, thereby informing future conservation efforts in impacted ecosystems
Impact of summer hypoxia on macrobenthic communities in a semi-enclosed bay: A long-term observation in the North Yellow sea of China
No full textThe O2 content of the global ocean has been declining progressively over the past decades, mainly because of human activities and global warming. Despite this situation, the responses of macrobenthos under hypoxic conditions remain poorly understood. In this study, we conducted a long-term observation (2015-2022) to investigate the intricate impact of summer hypoxia on macrobenthic communities in a semi-enclosed bay of the North Yellow Sea. Comparative analyses revealed higher macrobenthos abundance (1956.8 f 1507.5 ind./m2 vs. 871.8 f 636.9 ind./m2) and biomass (8.2 f 4.1 g/m2 vs. 5.6 f 3.2 g/m2) at hypoxic sites compared to normoxic sites during hypoxic years. Notably, polychaete species demonstrated remarkable adaptability, dominating hypoxic sites, and shaping community structure. The decline in biodiversity underscored the vulnerability and diminished resilience of macrobenthic communities to hypoxic stressors. Stable isotope analysis provided valuable insights into food web structures. The average trophic level of macrobenthos measured 2.84 f 0.70 at hypoxic sites, contrasting with the higher value of 3.14 f 0.74 observed at normoxic sites, indicating the absence of predators at high trophic levels under hypoxic conditions. Moreover, trophic interactions were significantly altered, resulting in a simplified and more vulnerable macrobenthic trophic structure. The findings underscored the importance of comprehensive research to understand the complex responses of macrobenthic communities to hypoxia, thereby informing future conservation efforts in impacted ecosystems
Ocean acidification aggravates the toxicity of deltamethrin in<i> Haliotis</i><i> discus</i><i> hannai:</i> Insights from immune response, histopathology and physiological responses
No full textOcean acidification (OA) and other environmental factors can collectively affect marine organisms. Deltamethrin (DM), a type II pyrethroid insecticide, has been widely detected in coastal and estuarine areas, while little attention has been given to the combined effects of DM and OA. In this study, Haliotis discus hannai was exposed to three pH levels (8.1, 7.7 and 7.4) and three DM nominal concentrations (0 mu g/L, 0.6 mu g/L and 6 mu g/L) for 14 and 28 days. The results indicated that experimental acidification and/or DM exposure led to impaired immune function and pathological damage. Additionally, acidified conditions and DM exposure induced oxidative stress, and gills are more sensitive than digestive glands. With increasing p CO 2 and DM nominal concentrations, superoxide dismutase (SOD) activity decreased, whereas catalase (CAT) and glutathione S-transferase (GST) activities increased in the gills. Moreover, the expression levels of Toll-like receptor (TLR) pathway-related genes were upregulated after exposure. Integrated biomarker response (IBR) analysis proved that acidified conditions and/or DM detrimentally affected the overall fitness of H. discus hannai, and co-exposure to experimental acidification and DM was the most stressful condition. This study emphasizes the necessity of incorporating OA in future pollutant environmental assessments to better elucidate the risks of environmental disturbance
寒潮和台风期间渤海波浪响应特征及动力机制研究
No full text寒潮和台风是影响我国海洋动力环境，造成海洋波浪灾害的重要天气过程。渤海作为我国最北端的内陆海，频繁受到寒潮影响。同时，由于近年来西北太平洋台风的强度和频率增大，并且台风路径呈现极向迁移趋势，渤海的台风事件也值得关注。由于受到风区限制和浅水环境作用的影响，半封闭海中的波浪动力学更为复杂，有进一步研究的必要性。本论文以渤海为研究海域，通过数值模拟和观测数据相结合的方法，对半封闭海在寒潮和台风期间的波浪特征及动力过程进行研究，从而为极端天气条件下波浪灾害的预报预警提供科学依据，并且为近岸工程建设与港口航道等项目的设计和施工提供重要参考。本研究主要包括以下三个部分。
首先，利用第三代波浪模型 SWAN（Simulating Waves Nearshore）模拟四次不同强度寒潮事件下（2014 和 2022 年西北风向与 2015 和 2021 年东北风向）渤海的波浪特征、时空演化、主导海况以及波高对风场（风向、风速、风时和风区等条件）的敏感性，对波浪在半封闭海的生成过程进行系统的研究。结果表明，在寒潮过程中，风是波浪产生的主要原因，各海区的海况主要是风浪主导的。由于两次寒潮事件的风区差异有限，并且高风速的持续时间较短，因此两者产生的最大有效波高数值相似。本研究还对各种波浪耗散所主导的海域进行空间量化，并对波浪向岸传播过程中各类能量耗散的变化情况进行讨论。白浪耗散在深水区占主导，当波浪向岸传播到达 5-10 米水深时，底摩擦耗散逐渐占主导。水深诱导的波浪能量耗散集中在南部近岸的一条狭长海域但强度明显高于白浪与底摩擦耗散。在此基础上将水动力模型 FVCOM（Finite Volume Community Ocean Model）与 SWAN 进行单向耦合，定量分析水位增减与海表流速对有效波高时空分布的影响。东北风寒潮事件中，南部近岸由于风暴潮增水导致该区域有效波高增大（最大值达到 0.59 米）；渤海中部海盆海表流向与波向趋于一致，这导致了有效波高减小（最大值达到-0.30 米）。
其次，应用 SWAN模拟五次不同路径台风事件中渤海波浪的时空变化特征。通过分析波浪谱数据，对波浪谱峰值个数、波浪能量密度以及主导海况进行研究。结果表明有效波高分布与台风路径和台风风场结构有关。从渤海中部穿过的台风（温比亚（2018）和烟花（2021））的高波浪能对应的主导海况为涌浪和混合海况，对应的时间段为台风中心到达前和离开后。对于沿渤海边缘经过的台风（麦德姆（2014）、利奇马（2019）和梅花（2022）），高波浪能对应的主导海况为风浪，对应的时间段为于台风中心经过时。在渤海，因为风区长度受到半封闭海地理特征限制，台风路径左侧（渤海湾）比路径右侧（莱州湾）的波浪能量密度高。在开阔海域中由于台风移动速度与气旋风速叠加，通常台风路径右侧的波浪能量密度较大，这突出体现了半封闭浅海与开阔大洋的差异性。在此基础上建立最大风速半径（ ）参考系，系统讨论不同象限内的波浪谱特征。研究表明，涌浪通常在 半径范围内占主导，而风浪主导其他区域。风浪和涌浪的传播方向具有显著差异的双峰波浪谱主要出现在第二、三象限的1/2 和 位置上。
最后，针针对台风和冷空气共同影响渤海的特殊事件利奇马（2019），采用修正的 Rankine 气旋模型进行混合风场分离。研究了台风气旋风场和背景西北向冷空气风场对波浪产生及主导海况的相对贡献。结果表明，当台风气旋的前部开始影响渤海时，混合风场对有效波高产生加强作用。随着冷空气侵入台风中心，混合风场与两类分离风场相比分别对不同海区的有效波高值产生了抑制作用。台风过境期间莱州湾的海况变化最强，台风中心进入莱州湾前，两类风场均具有正向作用，形成以涌浪为主导的海况；随着台风中心进入，莱州湾逐渐成为一个低风速海区，背景冷空气风场产生的涌浪占据主导地位。同时本文探讨了更频繁入侵渤海的东北冷空气与台风气旋叠加时的情况。研究发现，新的混合风场会在渤海湾湾口产生超过 7 米的灾害性波浪。这项工作揭示了台风和冷空气共同影响下渤海波浪的生成机制，提高了对此类特殊事件下波浪动力学机制研究的认识。
本工作通过对渤海在寒潮与台风等极端天气过程中的波浪动力学研究进行系统梳理，对近岸海区波浪预报模式改进以及波浪灾害的预警工作提供重要的科学参考。本论文涉及到海洋动力学中的强风、气旋、波浪生成、波高分布、海况、波浪能量耗散、风暴潮水位、流速等诸多研究对象，并且突出体现了风区有限的半封闭浅海中的波浪动力学相较于开阔大洋具有特殊性，将对其他半封闭海区在极端天气下的波浪研究具有重要的参考意义
Discovery of the First BRD4 Second Bromodomain (BD2)-Selective Inhibitors
No full textPan-BD2 inhibitors have been shown to retain an antileukemia effect and display less dose-limiting toxicities than pan-BET inhibitors. However, it is necessary to consider the potential off-target toxicity associated with the inhibition of four BET BD2 proteins. To date, no BRD4 BD2 domain selective inhibitor has been reported. Based on our previous pan-BD2 inhibitor 12 (XY153), we successfully identified 16o (XY221) as the first BRD4 BD2-selective inhibitor. 16o demonstrated potent binding affinity for BRD4 BD2 (IC50 = 5.8 nM), along with high pan-BD2 selectivity (667-fold over BRD4 BD1) and BRD4 BD2 domain selectivity (9-32-fold over BRD2/3/T BD2). The BRD4 BD2 selectivity of 16o was further confirmed by the BLI assay, showing 66-144-fold selectivity over other BET BD2 domains. 16o exhibited good liver microsomal stability (T-1/2 > 120 min) and pharmacokinetic properties (F = 13.1%). These data indicate that 16o may serve as a valuable candidate for BRD4 BD2 advancing epigenetic research
