Marine ciliates play important roles not only in linking the microbial loop to the classic pelagic and benthic food chains but also in regenerating nutrients, yet how dietary nutrient imbalance impacts their nutrient regeneration has not been thoroughly addressed. The growth and physiological responses of Euplotes vannus to low dietary nitrogen (LN) and low dietary phosphorus (LP) conditions were studied, with the bacterium Pseudomonas putida as prey. Feeding on LN prey reduced the growth rate of E. vannus. Dietary nutrient limitation changed the types and quantities of nutrient recycling. Feeding on LP prey enhanced dissolved organic carbon excretion but reduced orthophosphate excretion, whereas feeding on LN prey generally resulted in decreases in the excretion rate in all N forms (ammonium, urea, and nitrate). In addition, the proportion of ammonium in regenerated N increased significantly under the LN condition. These findings indicate that a nutrient-imbalanced diet triggers E. vannus to retain limited macronutrients and promotes the recycling of excessive macronutrients, which may potentially form positive and negative feedback to ambient N and P limitations, respectively.

Generally, a teleostean group (e.g., family or genus) owns one type or a set of similar mitochondrial gene arrangement. It is interesting, however, that four different types of gene arrangement have been found in the mitochondrial genome (mitogenome) of Cynoglossidae species. So far, the possible mechanisms of mitogenomic gene rearrangement and its potential implications have aroused widespread attention and caused lots of controversy. Here, a total of 21 Cynoglossidae mitogenomes and a newly sequenced mitogenome of Cynoglossus puncticpes (Pleuronectiformes: Cynoglossidae) were compared. The length ranges from 16 417 bp to 18 369 bp, which is mainly caused by the length heteroplasmy of control region (CR). Further analysis reveals that the difference of tandem repeats acts as a determining factor resulting in the length heterogeneity. Like most gene rearrangements of Cynoglossinae mitogenomes, tRNA-Gln gene encoded by the L-strand has translocated to the H-strand (Q inversion), accompanied by the translocation of CR in C. puncticpes mitogenome. The typical IQM order (tRNA-Ile-Gln-Met) changed to QIM order. Tandem duplication/random loss and mitochondrial recombination were accepted as the most possible models to account for the rearrangements in C. puncticpes mitogenome. Phylogenetic trees showed a strong correlation between the gap spacer in the rearranged QIM area and phylogeny, which provides a fresh idea for phylogenetic studies in future.

In this study, Ulva prolifera protein was used for preparing angiotensin-I converting enzyme (ACE)-inhibitory peptide via virtual gastrointestinal digestion and in silico screening. Some parameters of the obtained peptide, such as inhibition kinetics, docking mechanism, stability, transport pathway, were explored by Lineweaver-Burk plots, molecular docking, in vitro stimulate gastrointestinal (GI) digestion and Caco-2 cells monolayer model, respectively. Then, a novel anti-ACE peptide LDF (IC₅₀, (1.66 ± 0.34) μmol/L) was screened and synthesized by chemical synthesis. It was a no-competitive inhibitor and its anti-ACE inhibitory effect mainly attributable to four Conventional Hydrogen Bonds and Zn701 interactions. It could keep activity during simulated GI digestion in vitro and was transported by peptide transporter PepT1 and passive-mediated mode. Besides, it could activate Endothelial nitric oxide synthase (eNOS) activity to promote the production of NO and reduce Endothelin-1 (ET-1) secretion induced by Angiotensin II (Ang II) in Human Umbilical Vein Endothelial Cells (HUVECs). Meanwhile, it could promote mice splenocytes proliferation in a concentration-dependent manner. Our study indicated that this peptide was a potential ingredient functioning on vasodilation and enhancing immunity.

Planktonic foraminifer Globigerinoides ruber (white) and Trilobatus sacculifer are the most frequently used mixed-layer dwelling species for reconstructing past oceanic environments. Specifically, the Mg/Ca ratios of these two foraminiferal species have been used for reconstructing tropical/subtropical changes in sea surface temperature (SST). However, these two species have different morphotypes, of which the spatial and temporal differences in Mg/Ca ratios and their influencing factors are still unclear. Our objective is to investigate the potential differences between the Mg/Ca ratios of these different morphotypes of G. ruber (white) and T. sacculifer in the western Philippine Sea (WPS) and determine their implications for the reconstruction of SST and upper-ocean structure. Mg/Ca measurements are made on two basic morphotypes of G. ruber (white) [sensu stricto (s.s.) and sensu lato (s.l.)] and T. sacculifer [with (w) and without (w/o) a sac-like final chamber] on samples of Site MD06-3047B from the WPS. Our results reveal that Mg/Ca ratios of different G. ruber morphotypes show consistent differences; and those of T. sacculifer morphotypes show staged variations since MIS 3. It is suggested to select a single morphotype for reconstructing SST changes using the Mg/Ca ratios of G. ruber and T. sacculifer in the WPS. Furthermore, the Mg/Ca ratios between G. ruber s.s. and G. ruber s.l. [Δ(Mg/Ca)_{G.ruber s.s.−s.l.}] downcore MD06-3047B covaries with indexes of summer monsoon. Combining with the core-top results, showing regional variation of differences in the Δ(Mg/Ca)_{G.ruber s.s.−s.l.} over the western tropical Pacific, we propose that Δ(Mg/Ca)_{G.ruber s.s.−s.l.} may tend to reflect summer mixed layer depth.

Marine spatial planning (MSP) is designed to divide the sea area into different types of functional zones, to implement corresponding development activities. However, the long-term impacts of anthropogenic activities associated with MSP practice on the marine microbial biosphere are still unclear. Yalu River Estuary, a coastal region in northeast of China, has been divided into fishery & agricultural (F&A) zone, shipping & port (S&P) zone and marine protected area (MPA) zone by a local MSP guideline that has been run for decades. To examine the effects of long-term executed MSP, benthic bacterial communities from different MSP zones were obtained and compared in this study. The results revealed significant differences in the bacterial community structure and predict functions among different zones. Bacterial genera enriched in different zones were identified, including SBR1031 in MPA, Woeseia and Sva0996 in S&P, and Halioglobus in F&A. In addition, correlations between some bacterial genera and sediment pollutants were uncovered. Furthermore, bacteria related to sulphide production were more abundant in the F&A zone, which was according to the accumulation of sulphides in this area. Moreover, bacteria associated with chemoheterotrophy and fermentation were more predominant in the S&P zone, consistent with high levels of organic matter and petroleum caused by shipping. Our findings indicated benthic bacterial communities could bring to light the anthropogenic activity footprints by different activities induced by long-term MSP practice.

Deep-water channel systems are important petroleum reservoirs, and many have been discovered worldwide. Understanding deep-water channel sedimentary elements and evolution is helpful for deep-sea petroleum exploration and development. Based on high-resolution 3D seismic data, the Miocene channel system in the deep-water Taranaki Basin, New Zealand, was analyzed by using seismic interpretation techniques such as interlayer attribute extraction and strata slicing. The channel system was divided into five composite channels (CC-I to CC-V) according to four secondary level channel boundaries, and sedimentary elements such as channels, slump deposits, inner levees, mass transport deposits, and hemipelagic drape deposits were identified in the channel system. The morphological characteristics of several composite channels exhibited stark variances, and the overall morphology of the composite channels changed from relatively straight to highly sinuous to relatively straight. The evolution of the composite channels involved a gradual and repeated process of erosion and filling, and the composite channels could be divided into three evolutionary stages: initial erosion-filling, later erosion-filling (multistage), and channel abandonment. The middle Miocene channel system may have formed as a consequence of combined regional tectonic activity and global climatic change, and its intricate morphological alterations may have been influenced by the channel’s ability to self-regulate and gravity flow properties. When studying the sedimentary evolution of a large-scale deep-water channel system in the Taranaki Basin during the Oligocene−Miocene, which transitioned from a passive margin to plate convergence, it can be understood how tectonic activity affected the channel and can also provide a theoretical reference for the evolution of the deep-water channels in areas with similar tectonic conversion environments around the world.

In the context of global warming and rapid environment change in the Arctic, the supply of organic matter (OM) has increased significantly and a large amount of OM are buried on the Arctic shelf. Studying the fate of OM in Arctic shelf sediments is crucial to understanding the global carbon sink. As a marginal sea of the Arctic Ocean, the Chukchi Sea is one of the most critical areas where OM is buried. Based on the surface sediment samples collected during the sixth Chinese National Arctic Research Expedition in the summer of 2014 and the Sino-Russian joint Arctic Research Expedition in the summer of 2016, this study takes amino acids (AAs) as the primary tool to explore the source and degradation of OM in the surface sediments of the Chukchi Sea. This study shows that total hydrolyzable amino acid (THAA) concentrations (dry weight) are high, with a mean value of (32.7 ± 15.8) μmol/g. Their spatial distribution is related to primary productivity, hydrodynamic conditions, sediment properties and other factors. The source of OM in the surface sediments of the Chukchi Sea is dominated by diatom-dominated marine productivity, with some input from terrestrial sources. Bacteria, as the main source of the D-enantiomer of AA (D-AA), not only have transforming effect on OM, but their cell walls and remnants likewise supply the OM pool. Based on a series of diagenetic indicators, we conclude that the OM in the surface sediments of the Chukchi Sea has undergone extensive degradation [DI (degradation index) = −0.59 ± 0.44], and the degradation degree in the slope is higher than that in the shelf. This study uses AA to explore the sources and degradation of OM in the sediments of the Chukchi Sea, which facilitates our understanding of OM transport and transformation on the Arctic shelf.

Caulerpa sertularioides is an invasive potential blooming green alga in China but it remains poorly studied. We studied the effects of ecological factors on its growth. Optimum conditions of ecological factors, i.e., irradiance, temperature, and salinity, for the growth of its fragments were determined in the response surface methodology (RSM). The specific growth rates (SGR) of the fragments were determined in single-factor experiment. The results show that the SGR of C. sertularioides peaked under the conditions of irradiance 37.5 μmol/(m²·s), temperature 25℃, and salinity 30. Meanwhile, using the Box-Behnken design, the conditions were further optimized and verified to be: irradiance 39.03 μmol/(m²·s), temperature 25.29℃, and salinity 30.06, under which the SGR reached 4.66%. The results provide new theoretical data and solutions for the cultivation, invasion prediction, and monitoring of Caulerpa species in China and the world. The RSM method may have great potential applications in the environmental adaptation characteristics of new macroalgal cultivars, intensive orientation cultured germplasm, and environmental hazard analysis of cultivated species in the field.

The composition, provenance, and genetic mechanism of sediment on different sedimentary units of the East China Sea (ECS) shelf are essential for understanding the depositional dynamics environment in the ECS. The sediments in the northern ECS shelf are distributed in a ring-shaped distribution centered on the southwestern Cheju Island Mud. From the inside to the outside, the grain size goes from fine to coarse. Aside from the “grain size effect”, hydrodynamic sorting and mineral composition are important restrictions on the content of rare earth elements (REEs). Based on the grain size, REEs, and clay mineral composition of 300 surface sediments, as well as the sedimentary genesis, the northern ECS shelf is divided into three geochemical zones: southwestern Cheju Island Mud Area (Zone Ⅰ), Changjiang Shoal Sand Ridges (Zone Ⅱ-1), Sand Ridges of the East China Sea shelf (Zone Ⅱ-2). The northern ECS shelf is mostly impacted by Chinese mainland rivers (the Changjiang River and Huanghe River), and the provenance and transport mechanism of sediments of different grain sizes is diverse. The bulk sediments come primarily from the Changjiang River, with some material from the Huanghe River carried by the Yellow Sea Coastal Current and the North Jiangsu Coastal Current, and less from Korean rivers. Among them, surface sediments in the southwestern Cheju Island Mud Area (Zone Ⅰ) come mostly from the Changjiang River and partly from the Huanghe River. It was formed by the counterclockwise rotating cold eddies in the northern ECS shelf, which caused the sedimentation and accumulation of the fine-grained sediments of the Changjiang River and the Huanghe River. The Changjiang Shoal Sand Ridges (Zone Ⅱ-1) were developed during the early-middle Holocene sea-level highstand. It is the modern tidal sand ridge sediment formed by intense hydrodynamic action under the influence of the Yellow Sea Coastal Current, North Jiangsu Coastal Current, and Changjiang Diluted Water. The surface sediments mainly originate from the Changjiang River and Huanghe River, with the Changjiang River dominating, and the Korean River (Hanjiang River) influencing just a few stations. Sand Ridges of the East China Sea shelf (Zone Ⅱ-2) are the relict sediments of the paleo-Changjiang River created by sea invasion at the end of the Last Deglaciation in the Epipleistocene. The clay mineral composition of the surface sediments in the study area is just dominated by the Changjiang River, with the North Jiangsu Coastal Current and the Changjiang Diluted Water as the main transporting currents.

Fine-grained silt is widely distributed in the Huanghe River Delta (HRD) in China, and the sedimentary structure is complex, meaning that the clay content in the silt is variable. The piezocone penetration test (CPTu) is the most widely approved in situ test method. It can be used to invert soil properties and interpret soil behavior. To analyse the strength properties of surface sediments in the HRD, this paper evaluated the friction angle and its inversion formula through the CPTu penetration test and monotonic simple shear test and other soil unit experiments. The evaluation showed that the empirical formula proposed by Kulhawy and Mayne had better prediction and inversion effect. The HRD silts with clay contents of 9.2%, 21.4% and 30.3% were selected as samples for the CPTu variable rate penetration test. The results show as follows. (1) The effects of the clay content on the tip resistance and the pore pressure of silt under different penetration rates were summarized. The tip resistance Q_t is strongly dependent on the clay content of the silt, the $ {B}_{q} $ value of the silt tends to 0 and is not significantly affected by the change of the CPTu penetration rate. (2) Five soil behavior type classification charts and three soil behavior type indexes based on CPTu data were evaluated. The results show that the soil behavior type classification chart based on soil behavior type index ${I}_{{\rm{SBT}}}$, the Robertson 2010 behavior type classification chart are more suitable for the silty soil in the HRD.