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Volume 42 ， Issue 1 ， 2024
- Abstract：The coupling between wind stress perturbations and sea surface temperature (SST) perturbations induced by tropical instability waves (TIWs) in the Pacific Ocean has been revealed previously and proven crucial to both the atmosphere and ocean. However, an overlooked fact by previous studies is that the loosely defined “TIWs” actually consist of two modes, including the Yanai wave-based TIW on the equator (hereafter eTIW) and the Rossby wave-based TIW off the equator (hereafter vTIW). Hence, the individual feedbacks of the wind stress to the bimodal TIWs remain unexplored. In this study, individual coupling relationships are established for both eTIW and vTIW, including the relationship between the TIW-induced SST perturbations and two components of wind stress perturbations, and the relationship between the TIW-induced wind stress perturbation divergence (curl) and the downwind (crosswind) TIW-induced SST gradients. Results show that, due to different distributions of eTIW and vTIW, the coupling strength induced by the eTIW is stronger on the equator, and that by the vTIW is stronger off the equator. The results of any of eTIW and vTIW are higher than those of the loosely defined TIWs. We further investigated how well the coupling relationships remained in several widely recognized oceanic general circulation models and fully coupled climate models. However, the coupling relationships cannot be well represented in most numerical models. Finally, we confirmed that higher resolution usually corresponds to more accurate simulation. Therefore, the coupling models established in this study are complementary to previous research and can be used to refine the oceanic and coupled climate models.Keywords：bimodal tropical instability waves;mesoscale air-sea interaction;coupled models;Yanai wave40|17|0Updated：2024-10-15
- Abstract：The Pacific subtropical cells (STCs) are shallow meridional overturning circulations connecting the tropics and subtropics, and are assumed to be an important driver of the tropical Pacific decadal variability. The variability of STCs under global warming is investigated using multimodal outputs from the latest phase of the Coupled Model Inter-comparison Project (CMIP6) and ocean reanalysis products. Firstly, the volume transport diagnostic analysis is employed to evaluate how coupled models and ocean reanalysis products reproduce interior STC transport. The variation of heat transport by the interior STC under the high-emissions warming scenarios is also analyzed. The results show that the multimodal-mean linear trends of the interior STC transport along 9°S and 9°N are -0.02 Sv/a and 0.04 Sv/a under global warming, respectively, which is mainly due to the combined effect of the strengthened upper oceanic stratification and the weakening of wind field. There is a compensation relationship between the interior STC and the western boundary transport in the future climate, and the compensation relationship of 9°S is more significant than that of 9°N. In addition, compared with ocean reanalysis products, the coupled models tend to underestimate the variability of the interior STC transport convergence, and thus may lose some sea surface temperature (SST) driving force, which may be the reason for the low STC-SST correlation simulated by the model. The future scenario simulation shows that the heat transport of interior STC is weakened under global warming, with a general agreement across models.Keywords：interior subtropical cell (STC);global warming;Coupled Model Inter-comparison Project (CMIP6);western boundary transport21|14|0Updated：2024-10-15
- Abstract：The thermal front in the oceanic system is believed to have a significant effect on biological activity. During an era of climate change, changes in heat regulation between the atmosphere and oceanic interior can alter the characteristics of this important feature. Using the simulation results of the 3D Regional Ocean Modelling System (ROMS), we identified the location of thermal fronts and determined their dynamic variability in the area between the southern Andaman Sea and northern Malacca Strait. The Single Image Edge Detection (SIED) algorithm was used to detect the thermal front from model-derived temperature. Results show that a thermal front occurred every year from 2002 to 2012 with the temperature gradient at the location of the front was 0.3 °C/km. Compared to the years affected by El Niño and negative Indian Ocean Dipole (IOD), the normal years (e.g., May 2003) show the presence of the thermal front at every selected depth (10, 25, 50, and 75 m), whereas El Niño and negative IOD during 2010 show the presence of the thermal front only at depth of 75 m due to greater warming, leading to the thermocline deepening and enhanced stratification. During May 2003, the thermal front was separated by cooler SST in the southern Andaman Sea and warmer SST in the northern Malacca Strait. The higher SST in the northern Malacca Strait was believed due to the besieged Malacca Strait, which trapped the heat and make it difficult to release while higher chlorophyll a in Malacca Strait is due to the freshwater conduit from nearby rivers (Klang, Langat, Perak, and Selangor). Furthermore, compared to the southern Andaman Sea, the chlorophyll a in the northern Malacca Strait is easier to reach the surface area due to the shallower thermocline, which allows nutrients in the area to reach the surface faster.Keywords：regional ocean modelling system;thermal front;Andaman Sea;Malacca Strait;single image edge detection algorithm13|10|0Updated：2024-10-15
Physics
- Abstract：The Nansha Block (NB) is one of the blocks separated from the southern margin of the South China Craton (SCC) by the western Pacific subduction, which contains rich information of geodynamic and tectonic transformation. To reveal the essence of western Paleo-Pacific subduction during the Triassic period, Well NK-1 in this block was selected for petrographic study, and published research data from other cooperative teams were compared. A double-cycle pattern of basic to neutral magmatic volcanism was established, and 36 lithological rhythmic layers and representative cryptoexplosive breccia facies and welded tuff bands were identified. Combined with a reanalysis of published geochronological data, geochemical elements, and isotope geochemistry, we found that the rock assemblages could be divided into an intermediate-acid dacite (DA) series (SiO2>65%) and basaltic (BA) series (Co<40 µg/g), which was formed during the early Late Triassic ((218.6±3.2)–(217.9±3.5) Ma). BA exhibits obvious calc-alkaline island-arc magmatic properties: (87Sr/86Sr)i ratio ranging 0.703 77–0.711 18 (average: 0.706 45), 147Sm/144Nd ratio ranging 0.119–0.193 (average: 0.168), and chondrite-normalized rare earth element (REE) curves being flat, while DA exhibits remarkable characteristics of subducted island-arc andesitic magma: (87Sr/86Sr)i ratio (0.709 39–0.711 29; average: 0.710 35),εNd(t) value (-6.2–-4.8; average: -5.6) and εHf(t) value (-2.9–-1.7, average: -2.2) show obvious crust-mantle mixing characteristics. BA and DA reveal typical characteristics of island-arc magma systems and type Ⅱ enriched mantle (EM-Ⅱ) magma. BA magma was likely resulted from the process whereby the continental crust frontal accretionary wedge was driven by the Paleo-Pacific slab subduction into the deep and began to melt, resulting in a large amount of melt (fluid) joined the asthenosphere on the side of the continental margin. In contrast, DA magma was likely resulted from the process whereby the plate front was forced to bend with increasing subduction distance, which triggered the upwelling of the asthenosphere near the continent and subsequently led to the partial melting of the lithospheric mantle and lower crust due to continuous underplating. The lithospheric thinning environment in the study area at the end of Triassic created suitable conditions for the separation between the NB and SCC, which provided an opportunity for the formation of the early intracontinental rift during the later expansion of the South China Sea (SCS).Keywords：Paleo-Pacific tectonic domain;tectonic evolution;rift volcanic rock;Nansha Block;South China Craton17|10|0Updated：2024-10-15
- Abstract：The inhomogeneous sound speed in seawater causes refraction of sound waves, and the elimination of the refraction effect is essential to the accuracy of underwater acoustic positioning. The ray-tracing method is an indispensable tool for effectively handling problems. However, this method has a conflict between localization accuracy and computational quantity. The equivalent sound speed profile (ESSP) method uses a simple sound speed profile (SSP) instead of the actual complex SSP, which can improve positioning precision but with residual error. The residual error is especially non-negligible in deep water and at large beam incidence angles. By analyzing the residual error of the ESSP method through a simulation, an empirical formula of error is presented. The data collected in the sailing circle mode (large incidence angle) of the South China Sea are used for verification. The experiments show that compared to the ESSP method, the improved algorithm has higher positioning precision and is more efficient than the ray-tracing method.Keywords：underwater acoustic positioning;seafloor datum points;large incident angle;equivalent sound speed profile (ESSP);deep water19|4|0Updated：2024-10-15
Geology
- Abstract：Freshwater microplastic pollution is an urgent issue of global concern, and research on the distribution in reservoirs is lacking. We investigated the microplastic pollution levels in wet sediments collected from the Three Gorges Reservoir, the largest reservoir of China. Results show that microplastics were ubiquitous in the sediments of the Three Gorges Reservoir, and their abundance ranged from 59 to 276 pp/kg (plastic particles per kg, dry weight). Economic development and total population were important factors affecting the spatial heterogeneity of microplastic abundance, and the contribution of large cities along the reservoir to microplastic pollution should be paid with more attention. Fibrous microplastics were the most abundant type of microplastic particles in reservoir sediments, whereas polystyrene, polypropylene, and polyamide were the main types of polymers. The apparent spatial heterogeneity in morphology and color of microplastics is attributed to different anthropogenic or land-based pollution sources. Moreover, the accumulation of microplastics near the inlet of tributaries reflects the role of potential contributors of tributaries. More importantly, multiple bisphenols (BPs) and heavy metals detected at the microplastic surfaces indicate that microplastics can act as carriers of these pollutants in the environment in the same way as sediments did, which may alter the environmental fate and toxicity of these pollutants. Therefore, we conclude that the Three Gorges Reservoir had been contaminated with microplastics, which posed a stress risk for organisms who ingest them along with their associated pollutants (BPs, heavy metals).Keywords：microplastics;Three Gorges Reservoir;sediment;bisphenol;heavy metal19|6|0Updated：2024-10-15
Chemistry
- Abstract：The inhomogeneous sound speed in seawater causes refraction of sound waves, and the elimination of the refraction effect is essential to the accuracy of underwater acoustic positioning. The ray-tracing method is an indispensable tool for effectively handling problems. However, this method has a conflict between localization accuracy and computational quantity. The equivalent sound speed profile (ESSP) method uses a simple sound speed profile (SSP) instead of the actual complex SSP, which can improve positioning precision but with residual error. The residual error is especially non-negligible in deep water and at large beam incidence angles. By analyzing the residual error of the ESSP method through a simulation, an empirical formula of error is presented. The data collected in the sailing circle mode (large incidence angle) of the South China Sea are used for verification. The experiments show that compared to the ESSP method, the improved algorithm has higher positioning precision and is more efficient than the ray-tracing method.Keywords：underwater acoustic positioning;seafloor datum points;large incident angle;equivalent sound speed profile (ESSP);deep water16|8|0Updated：2024-10-15
- Abstract：Cyanea nozakii, a common jellyfish distributed in offshore China, has a complex trophic relationship with other zooplankton groups. However, few studies have reported the predation rates and prey selection patterns of C. nozakii medusae on different prey items. Research is also lacking on the intraguild predation of Aurelia coerulea (another common bloom jellyfish in offshore China) by C. nozakii. To address the knowledge gaps, the clearance rates of C. nozakii for different prey items, including copepods (small<1 000 μm and large>1 000 μm), fish larvae, and gelatinous prey (hydromedusae, A. coerulea ephyrae, and chaetognaths), were measured. The influence of predator size on the clearance rate was also determined. Additionally, we examined the intraguild predation of C. nozakii on A. coerulea medusae. The clearance rates of C. nozakii varied widely with prey organisms, being independent of prey concentrations. Gelatinous organisms, except for chaetognaths, were captured with considerably high efficiency, followed by fish larvae and copepods, indicating the preferential prey selection of gelatinous organisms by C. nozakii. The clearance rate increased linearly with the cross-sectional area of C. nozakii. Body size in medusae may, to some extents, underpin their capacity to capture more prey by increasing the encounter rate and capture success through ontogeny. C. nozakii preyed voraciously on A. coerulea in high feeding efficiency, but the clearance rate decreased with increasing A. coerulea (as prey) size. This phenomenon of intraguild predation suggests a speculative hypothesis of potential population regulation of A. coerulea by C. nozakii. The information regarding the feeding ecology of C. nozakii reported in this study is important for understanding plankton dynamics in marine ecosystems with extensive occurrences of this jellyfish.Keywords：scyphomedusae;predation rate;gelatinous organisms;prey selection;feeding mechanism24|3|0Updated：2024-10-15
- Abstract：Phaeocystis globosa is an important unicellular eukaryotic alga that can also form colonies. P. globosa can cause massive harmful algal blooms and plays an important role in the global carbon or sulfur cycling. Thus far, the ecophysiology of P. globosa has been investigated by numerous studies. However, the proteomic response of P. globosa to nitrogen depletion remains largely unknown. We compared four protein preparation methods of P. globosa for two-dimensional electrophoresis (2-DE) (Urea/Triton X-100 with trichloroacetic acid (TCA)/acetone precipitation; TCA/acetone precipitation; Radio Immuno Precipitation Assay (RIPA) with TCA/acetone precipitation; and Tris buffer). Results show that the combination of RIPA with TCA/acetone precipitation had a clear gel background and showed the best protein spot separation effect, based on which the proteomic response to nitrogen depletion was studied using 2-DE. In addition, we identified six differentially expressed proteins whose relative abundance increased or decreased more than 1.5-fold (P<0.05). Most proteins could not be identified, which might be attributed to the lack of genomic sequences of P. globosa. Under nitrogen limitation, replication protein-like, RNA ligase, and sn-glycerol-3-phosphate dehydrogenase were reduced, which may decrease the DNA replication level and ATP production in P. globosa cells. The increase of endonuclease Ⅲ and transcriptional regulator enzyme may affect the metabolic and antioxidant function of P. globosa cells and induce cell apoptosis. These findings provide a basis for further proteomic study of P. globosa and the optimization of protein preparation methods of marine microalgae.Keywords：Phaeocystis globosa;nitrogen limitation;proteomic response;two-dimensional electrophoresis16|3|0Updated：2024-10-15
- Abstract：Pyraclostrobin (PYR), a widely used fungicide, has negative effects on fish and algae, but its toxicity in protozoa remains unclear. In this study, the effects of PYR on the growth, oxidative stress, and gene expression related to stress and ATP-binding cassette (ABC) transporters in Tetrahymena thermophila were investigated. The result showed that the 96-h IC50 of PYR against T. thermophila was 17.2 mg/L. Moreover, PYR inhibited the growth of T. thermophila in concentration- or time-dependent manner. A morphological study revealed that the shape and size of T. thermophila changed, and damage of cell membrane surface was observed by scanning electron microscopy after 96 h of PYR exposure. The activities of superoxide dismutase (SOD) and catalase (CAT) increased throughout the experiment. In contrast, the glutathione (GSH) content was increased at 24 h and 48 h of exposure and decreased at 96 h. Moreover, a significant increase in malondialdehyde (MDA) level was observed in T. thermophila after 96 h of exposure. Furthermore, PYR upregulated the HSP703, HSP705, GPx2, and ABAC15 gene expression in the 0.1–5-mg/L groups and downregulated the HSP704, HSP90, TGR, and ABCC52 mRNA levels at 96 h of exposure. These results suggest that PYR may exert adverse effects on T. thermophila by inducing oxidative stress and changing the gene expression related to ABC transporters and stress, which may enrich the understanding of the toxicity mechanism of PYR in aquatic organisms and provide reference data for aquatic ecological risk assessments.Keywords：pyraclostrobin;Tetrahymena thermophila;growth;oxidative stress;gene expression15|5|0Updated：2024-10-15
- Abstract：Deltamethrin (DEL), a commonly used pyrethroid pesticide, results in higher reactive oxygen species (ROS) levels in aquatic animals, which consequently unbalance the redox state. Phlorizin (PHL) is a flavonoid and a natural product promising to prevent or reduce pesticide-induced oxidative stress. Artemia is a micro-crustacean widely used in marine hatcheries and an experimental aquatic organism for environmental toxicology research. This research aimed to evaluate the toxicity of DEL on Artemia and the antioxidative effect of PHL against the toxicity. Results show that 0.08-mg/mL PHL exerted its antioxidative effects on hatching percentage of the cysts in 24-h incubation and on body length and survival rate of Artemia in 12-d culture. After 12-d culture, 12-, 24-, and 36-h DEL exposure showed significant drops in SOD, CAT, and GSH-Px enzyme activities, and significant increases in ROS and malondialdehyde (MDA) levels in Artemia (P<0.05). On the contrary, 0.08-mg/mL PHL application improved the enzyme activities and decreased the ROS and MDA levels (P<0.05). Moreover, 0.08-mg/mL PHL significantly increased mRNA expression levels of Cu/Zn SOD, CAT, GST, HO-1, NQO1, and Nrf2, and decreased mRNA expression level of Keap1 in the DEL-exposed Artemia (P<0.05). Therefore, DEL is toxic to Artemia, while PHL alleviates DEL-induced oxidative damage by possibly regulating the Nrf2 signaling pathway. This study provided a theoretical basis for PHL to reduce pesticide-induced toxicity in aquatic animals.Keywords：Artemia;deltamethrin;phlorizin;oxidative stress14|5|0Updated：2024-10-15
Ecology
- Abstract：Light plays an important role in the photosynthesis and metabolic process of microalgae. However, how different light conditions regulate the biomass production and protein accumulation of microalgae is mostly unknown. In this study, the influence of different light conditions, including light colors, densities, and light꞉dark cycles on the cell growth and biochemical composition of Spirulina platensis was symmetrically characterized. Under different colored lights, S. platensis all shows an increase trend within the increased light intensity ranges; however, each showing different optimal light intensities. At the same light intensity, different colored lights show different growth rate of S. platensis following the sequence of red>white>green>yellow>blue. The maximum growth rate and protein accumulation were determined as 21.88 and 5.10 mg/(L·d) when illuminated under red LED. The energy efficiency of different light sources was calculated and ranked as red>white>blue≈green>yellow. Transcriptomic analysis suggests that red light can promote cell growth and protein accumulation by up-regulating genes related to photosynthesis, carbon fixation, and C-N metabolism pathways. This study provides a conducive and efficient way to promote biomass production and protein accumulation of S. platensis by regulating light conditions.Keywords：microalgae;light emitting diode;protein accumulation;biomass production;transcriptomic analysis36|4|0Updated：2024-10-15
- Abstract：Mitochondria undergo morphological changes during spermatogenesis in some animals. The mechanism and role of mitochondrial morphology regulation, however, remain somewhat unclear. In this study, we analyzed the molecular characteristics, expression dynamics and subcellular localization of optic atrophy protein 1 (OPA1), a mitochondrial fusion and cristae maintenance-related protein, to reveal the possible regulatory mechanisms underlying mitochondrial morphology in Phascolosoma esculenta spermiogenesis. The full-length cDNA of the P. esculenta opa1 gene (Pe-opa1) is 3 743 bp in length and encodes 975 amino acids. The Pe-OPA1 protein is highly conservative and includes a transmembrane domain, a GTPase domain, two helical bundle domains, and a lipid-interacting stalk. Gene and protein expression was higher in the coelomic fluid (a site of spermatid development) of male P. esculenta and increased first and then decreased from March to December. Moreover, their expression during the breeding stage was significantly higher than during the non-breeding stage, suggesting that Pe-OPA1 is involved in P. esculenta reproduction. The Pe-OPA1 protein was more abundant in components consisting of many spermatids than in components without, indicating that Pe-OPA1 mainly plays a role in the spermatid in coelomic fluid. Moreover, Pe-OPA1 was mainly detected in the spermatid mitochondria. Immunofluorescence experiments showed that the Pe-OPA1 are constitutively expressed and co-localized with mitochondria during spermiogenesis, suggesting its involvement in P. esculenta spermiogenesis. These results provide evidence for Pe-OPA1’s involvement in the regulation of mitochondrial morphology during spermiogenesis.Keywords：optic atrophy protein 1 (OPA1);spermiogenesis;Phascolosoma esculenta;mitochondrial dynamics;spermatid19|4|0Updated：2024-10-15
- Abstract：Regulation of microRNAs (miRNAs) on various biological processes has been a surprising and exciting field. Identification of miRNAs is the first step to comprehensively understand their functions. However, attempts on global identification and functional verification of miRNAs are very limited in penaeid shrimp Marsupenaeus japonicus, an economically important aquatic species. By performing an integrated analysis of transcriptomic profile from gastrula embryos of M. japonicus, 21 conserved miRNAs in M. japonicas (mja-miRNAs), belonging to 19 miRNA families, were identified and characterized. Of the 21 mja-miRNAs, 15 miRNAs were successfully verified to be predominantly expressed in gastrula stage, where they displayed dynamic expression patterns compared with those in naupliuin stage. Based on perfect or near-perfect match to target region, 120 target genes were predicted at transcriptome-wide level. Noteworthy, gene ontology (GO) classification and metabolic pathway annotation revealed eight targets that were actively involved in developmental processes. Of the predicted miRNA-mRNA pairs, six targets were then randomly selected and experimentally validated by dual luciferase reporter assay, where three pairs were proved with potential targeting activity. Overall, to search for conserved miRNAs potentially involved in early development of M. japonicus, we combined in silico and experimental methods, which can be applied in other organisms as well. Our data implied important roles of miRNAs in the early embryonic development and also suggested the presence of complex miRNA-mRNA functional networks in M. japonicus.Keywords：microRNAs (miRNAs);identification;Marsupenaeus japonicus;embryo;transcriptome21|2|0Updated：2024-10-15
- Abstract：Insertional mutation, phenotypic evaluation, and mutated gene cloning are widely used to clone genes from scratch. Exogenous genes can be integrated into the genome during non-homologous end joining (NHEJ) of the double-strand breaks of DNA, causing insertional mutation. The random insertional mutant library constructed using this method has become a method of forward genetics for gene cloning. However, the establishment of a random insertional mutant library requires a high transformation efficiency of exogenous genes. Many microalgal species show a low transformation efficiency, making constructing random insertional mutant libraries difficult. In this study, we established a highly efficient transformation method for constructing a random insertional mutant library of Nannochloropsis oceanica, and tentatively tried to isolate its genes to prove the feasibility of the method. A gene that may control the growth rate and cell size was identified. This method will facilitate the genetic studies of N. oceanica, which should also be a reference for other microalgal species.Keywords：Nannochloropsis oceanica;genetic transformation;random insertional mutant library;zeocin pretreatment;forward genetics11|3|0Updated：2024-10-15
- Abstract：Island ecosystems support diverse aquatic invertebrate communities comprising endemic taxa. Documentation of existing species is important for conservation. In this study, a checklist of marine opisthobranch from the Republic of Mauritius is presented. A combination of benthic surveys (50 m×5 m in triplicates), rover diving techniques and photo documentation were used over two years (2018–2020) within 35 sheltered and unsheltered lagoons. Morphological and molecular analysis were used for identification. Species composition within sheltered and unsheltered areas in Mauritius was estimated using the Bray-Curtis similarity. The checklist featured 117 species belonging to 61 genera and 28 families, of which 13 are new records. The findings increased the knowledge of opisthobranch diversity from the Mauritius by 15.4%. Among the listed species, the distribution range of Cyerce nigra, Actinocyclus papillatus, and Phyllidia picta extended from the Western Pacific to the South Western Indian Ocean. Molecular analysis of the undescribed Gymnodoris sp. showed it resembled Gymnodoris sp. from Hawaii and were different by a genetic distance value of 10.6%. The species richness and evenness were higher within the sheltered regions of Mauritius which harboured the food resource of opisthobranch. These areas as compared to unsheltered regions were heavily populated, suggesting the probable influence of wave actions on opisthobranch diversity and abundance. The order Nudibranchia was reported as most speciose, with 86 species. The Sacoglossa and Nudibranchia were observed only on macroalgae and sponges respectively. High abundance was also recorded on shipwrecks which are the most common form of artificial reefs. With the inclusion of observations from previous studies, 201 species belonging to 94 genera and 36 families are now known from the Mauritius.Keywords：marine opisthobranch;inventory;new record;occurrence;Republic of Mauritius;Indian Ocean11|2|0Updated：2024-10-15
- Abstract：One specimen belonging to the family Comatellinae was collected from the Zhenbei Seamount (332.5–478.2 m) in the South China Sea in July 2022. Based on the morphological characters, the specimen was identified as Palaeocomatella hiwia McKnight, 1977. It is first recorded from China Sea and redescribed in detail. This specimen differs from the original description from New Zealand for never showing syzygy at br4+5 or br5+6 on interior and br1+2 on exterior arms. However, it is much conform to the redescription to specimens from Indonesia, with only differences in position of the second syzygy and distalmost pinnule comb. Specimen is deposited in the Institute of Oceanology, Chinese Academy of Sciences. Phylogenetic analyses based on the mitochondrial c oxidase subunit I (COI) and 16S rRNA genes indicated that P. hiwia was nested within the tribe Phanogeniini and clustered with Aphanocomaster pulcher. Furthermore, P. hiwia showed same morphological features in terms of mouth placement, comb location, and number of comb teeth rows as other genera of Phanogeniini. Therefore, we suggest that the genus Palaeocomatella should be put in the tribe Phanogeniini.Keywords：new record;Palaeocomatella hiwia McKnight, 1977;South China Sea;phylogenetic relationship;taxonomy12|5|0Updated：2024-10-15
- Abstract：Benthodytes occidentpalauta sp. nov. was collected from the Kyushu-Palau Ridge at a depth of 5 481 m in 2021. This new species is characterized by a gelatinous body wall, violet skin, six pairs of dorsal papillae, and a rough mid-ventral surface without tube feet. The dorsal deposits are rod-shaped and tripartite. Two types of papillae deposits as crosses with four arms with central bipartite apophyses. Ventral deposits are rods. Tentacle ossicles are rod-shaped with end protrusions. Gonad deposits are rod-shaped, tripartite, and cross-shaped. The phylogenetic analyses based on cytochrome oxidase subunit 1 (COI) and 16S individually and a concatenated dataset of COI and 16S genes of this species support that B. occidentpalauta sp. nov. belongs to Benthodytes.Keywords：Holothuroidea;Benthodytes;cytochrome oxidase subunit 1 (COI);16S;phylogenetic analysis10|4|0Updated：2024-10-15
- Abstract：A new filamentous cyanobacterial strain (CHAB 4127) was successfully isolated from the algal mat during the field investigation of the open channel from Luanhe River to Tianjin, China. The polyphasic approach combining morphological, ultrastructural, ecological, and molecular features was used to characterize this studied strain. The strain is morphologically similar to the Microcoleus-like cyanobacterial taxa under light microscopy, and the radial arrangement of thylakoids is also consistent with that of Microcoleus-like groups. The phylogenetic position of CHAB 4127 based on 16S rRNA gene sequences, is shown to be clearly clustered into an independent clade with the newly established genus Microcoleusiopsis. The maximum similarity of 16S rRNA gene of the studied strain with other existing related cyanobacterial taxa is 93.97%, and the ITS secondary structures is also obviously different from other members of Microcoleaceae. Based on all the above evidence, we proposed the establishment of this novel cyanobacterial genus as Neomicrocoleus, with its type species, Neomicrocoleus tianjinensis.Keywords：Neomicrocoleus tianjinensis;morphology;16s rRNA;taxonomy;polyphasic approach13|3|1Updated：2024-10-15
- Abstract：Based on a combination of morphology and molecular data of ribosomal DNA genes, a new diatom genus Lineaperpetua gen. nov. Yu, You, Kociolek & Wang is described. The features that help define Lineaperpetua at the level of genus include: a tangentially undulated valve face; continuous cribra areolae on the valve interior consisting of pores arranged as strips; single rimoportula located inside the ring of marginal fultoportulae. Additionally, phylogenetic analysis based on nuclear small subunit (SSU) rDNA sequences and nuclear large subunit (LSU) rDNA gene placed the three strains of L. lacustris in a single, monophyletic clade at a considerable sequence distance from the other genera (Thalassiosira, Conticribra, Planktoniella, Shinodiscus, and other genera) belonging to Thalassiosirales. Despite the similarities with some species of Thalassiosira, Conticribra, and Spicaticribra, the suite of features found in Lineaperpetua differentiate it from these other genera. These molecular data and morphological characters suggest an affinity of the new genus to the Thalassiosiraceae.Keywords：diatom;morphology;new genus;phylogeny;taxonomy;Thalassiosiraceae13|8|0Updated：2024-10-15
- Abstract：During our investigation of diatom biodiversity in Xizang, two species exhibited unique morphological features discriminative from all previously known genera. Herein we describe these two species and describe as new the genus, Spargeria gen. nov. The new genus features narrow to wide rectangular valves, narrow valve mantles, filiform raphe branches that occur on the valve face only, terminal raphe fissures straight or slightly deflected to same side, bow-tie shaped central areas, chambered striae present on the valve face only, being absent from the mantle, wider striae near the axial area and very narrow near the margin, multiseriate striae with small and round areolae that are occluded externally. Comparatively, Spargeria zhuii sp. nov. has larger and robust valves, radiate striae, with one divergent stria near the apices, while Spargeria chenia sp. nov. is smaller, with narrow valves, striae slightly radiate in the middle, becoming convergent or parallel near apices. This new genus belongs to the family Pinnulariaceae, and it was compared and contrasted with other genera of this family. Our work suggests the need for continued studies to document the biodiversity of diatoms in Xizang.Keywords：Spargeria;new genus;Pinnulariaceae;morphology;Xizang14|8|0Updated：2024-10-15
Biology
- Abstract：The two bay scallop subspecies, Argopecten irradians irradians (NN) and A. i. concentricus (SS), are fast growing and major cultured bivalves in China. However, their relatively small sizes and decreasing production traits caused by long-term inbreeding have been major concerns to the industry in the last two decades. Hybridization between the two bay scallop subspecies may provide a new approach to breed a new variety with superior production traits for the industry. For this end, in this study, we hybridized the two bay scallop subspecies in order to obtain a new strain that incorporates the genes of both subspecies. No significant difference was found in fertilization rate, hatching rate and metamorphosis rate between the purebred and crossbred cohorts (NN♀×SS♂, denoted as NS; SS♀×NN♂, denoted as SN). Both mating strategy (intra- vs. inter-population crosses) and egg origin had significant effects on growth and survival at the larval stage. Heterosis was observed in the crossbred and was more pronounced in older stages. Genetic diversity of the reciprocal hybrids, especially that of SN, was increased compared with the purebred cohorts. Almost all hybrids were completely fertile and able to reproduce by self-fertilization or by backcrossing with either parent. Apparently, male sterile individuals whose gonads were fully occupied by the ovary part at mature stage were found in the hybrids for the first time. The hybrids, especially SN, may provide precious germplasm resources for the production of ternary hybrids with the Peruvian scallop, A. purpuratus.Keywords：bay scallop;hybridization;growth;heterosis;fertility;ternary hybrids14|7|0Updated：2024-10-15
- Abstract：The aquaculture industry has developed significantly over the past few decades and has had a substantial impact on the global food supply and marine fisheries resources. However, some problems arise behind the scenes due to excessive intensive farming, such as slow animal growth, frequent disease, and lipid metabolism disorders. These problems have limited the sustainable development of the aquaculture industry, and a continuable solution is required. The use of fungal polysaccharide appears to provide a solution to these problems. Therefore, different supplemented levels of Poria cocos polysaccharide (PCP) (0, 0.4, 0.8, 1.2, 1.6, and 2.0 g/kg, respectively) were fed to spotted sea bass (Lateolabrax maculatus) in similar size (30.28±0.18 g) in current study. The effects of PCP on growth, physiological parameters, and lipid metabolism of spotted sea bass were investigated after a 4-week rearing period. Results showed, fish with PCP intake presented a significantly higher weight gain, specific growth rate, and a significantly lower feed conversion ratio. Significantly higher trypsin activity in liver and intestine were observed in fish with PCP intake. The superoxide dismutase activity in serum and liver of fish with PCP intake were significantly improved, while significantly higher serum total antioxidant capacity and hepatic catalase activity were also observed. However, no significant differences in lysozyme and alkaline phosphatase activity were evident among groups. Fish with PCP intake showed a significantly lower total cholesterol, but no noteworthy change in triglyceride and lipid-metabolism-related genes expression were observed among groups. Results indicated that intake of PCP has a positive effect on growth and antioxidant capacity of spotted sea bass, but seems to have a limited effect on the non-specific immunity and lipid metabolism of spotted sea bass. Based on the regression analysis results, 1.4 g/kg of PCP is the optimal dose for spotted sea bass in size (30.28±0.18 g).Keywords：spotted sea bass;Poria cocos;polysaccharide;growth;lipid metabolism13|4|0Updated：2024-10-15
- Abstract：Turbot Scophthalmus maximus is an important mariculture fish species with high economic value. However, the bacterial diseases caused by Vibrio anguillarum infection bring huge economic losses to the turbot aquaculture industry. To understand the immune response of the turbot against V. anguillarum infection and to explore novel immune-related genes, the transcriptome analysis of turbot spleen and gills were conducted after V. anguillarum infection. Differentially expressed genes (DEGs) were identified in spleen and gill of the turbot amounted to 17 261 and 16 436, respectively. A large number of immune-related DEGs were enriched in cytokine-cytokine receptor interaction signaling pathway, and the others by the kyoto encyclopedia of genes and genomes (KEGG) enrichment. The gene ontology (GO) classification analysis revealed that V. anguillarum infection had the greatest effect on biological processes and cellular components. Twelve immune-related DEGs were identified in the spleen (cstl.1, egfl6, lamb21, v2rx4, calcr, and gpr78a) and gills (ghra, sh3gl2a, cst12, inhbaa, cxcl8, and il-1b) by heat map. The protein-protein interaction (PPI) networks were constructed to analyze the immune mechanism. The results demonstrate that the maturation and antigen processing of major histocompatibility complex (MHC) class II molecule, and calcitonin- or adrenomedullin-regulated physiological activity were important events in the immunity of turbot against V. anguillarum infection. In the gills, the protein interactions in TGF-β signaling pathway, production of inflammatory factors, and endocytosis regulation were most significant. Our research laid a foundation for discovering novel immune-related genes and enriching the knowledge of immune mechanisms of turbot against V. anguillarum infection.Keywords：Scophthalmus maximus;Vibrio anguillarum;transcriptome;differentially expressed genes;immune mechanism12|9|0Updated：2024-10-15
- Abstract：Spatial heterogeneity or “patchiness” of plankton distributions in the ocean has always been an attractive and challenging scientific issue to oceanographers. We focused on the accumulation and dynamic mechanism of the Acetes chinensis in the Lianyungang nearshore licensed fishing area. The Lagrangian frame approaches including the Lagrangian coherent structures theory, Lagrangian residual current, and Lagrangian particle-tracking model were applied to find the transport pathways and aggregation characteristics of Acetes chinensis. There exist some material transport pathways for Acetes chinensis passing through the licensed fishing area, and Acetes chinensis is easy to accumulate in the licensed fishing area. The main mechanism forming this distribution pattern is the local circulation induced by the nonlinear interaction of topography and tidal flow. Both the Lagrangian coherent structure analysis and the particle trajectory tracking indicate that Acetes chinensis in the licensed fishing area come from the nearshore estuary. This work contributed to the adjustment of licensed fishing area and the efficient utilization of fishery resources.Keywords：plankton accumulation;hydrodynamic model;Lagrangian particle-tracking model;Lagrangian analysis13|5|1Updated：2024-10-15
Aquaculture and Fisheries
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