- NIE Yuhua;CHEN Zhiwu;XIE Jieshuo;XU Jiexin;HE Yinghui;CAI Shuqun;
Direct numerical simulations are performed to investigate the generation of internal waves by tide-topography interaction in a lab-scale model. The bottom topography is a triangular ridge with two critical slopes. With increasing tidal forcing, subharmonic instabilities are identified, which cause internal wave beams to become unstable and turbulent. Kinetic energy densities in the upward going beams from the ridge top are stronger than those from the ridge bottom, whereas the reverse is true for the energy flux. This disparity between energy and energy flux is due to the existence of strong pressure disturbances near the ridge bottom. On each side of the critical ridge, there exists an amphidromic point, from which internal wave beams are emitted in opposite directions. The calculated energy conversion rate scales linearly with the square of the forcing amplitude and agrees within 13% of theoretical prediction, even when turbulence occurs. The fraction of radiated baroclinic energy becomes saturated in the range of low excursion parameter considered, which agrees with the behavior in large-scale systems wherein mixing parameterizations must be used. The present work enriches the studies on the generation of internal waves over a critical triangular ridge.
2019年05期 v.18 1005-1012页 [查看摘要][在线阅读][下载 929K] - WANG Guanlin;LI Dawei;WEI Zexun;LI Shujiang;WANG Yonggang;XU Tengfei;
This study examined the characteristics and vertical propagation of near inertial waves(NIWs) induced by Typhoon Linfa(2015), based on in situ observations conducted southeast of Dongsha Islands in the South China Sea. The results demonstrate that the near inertial currents induced by Linfa had velocities up to 35 cm s-1 in the mixed layer and 20 cm s-1 in the ocean interior. The near inertial currents were polarized with predominantly clockwise-rotating components, the magnitudes of which were about 10 times larger than the counter-clockwise rotating components. The energy density spectrum showed that the emergence of NIWs resulted in energy redistribution from the diurnal band to the near inertial band. The wavenumber spectrum and the downward/upward current decomposition demonstrated that the NIWs and energy flux propagated mainly downward. The estimated vertical phase velocity and group velocity are 1.44 and 0.48 m h-1, respectively, corresponding to a vertical wavelength of 49.7 m. The e-folding time scale was 7.5 d based on the near inertial kinetic energy in the ocean interior. We found no obvious wave–wave interaction during the decay process of the NIWs. The frequency was blue-shifted, being 0.03 f0 higher than the local inertial frequency, which was caused by the background vorticity. The normal mode analysis suggests that the higher mode plays a dominant role in the propagation stage of the NIWs.
2019年05期 v.18 1013-1021页 [查看摘要][在线阅读][下载 1793K] - GUO Xiangming;ZHAO Dongliang;ZHANG Lijun;WANG Hongguang;KANG Shifeng;
Evaporation duct is an ubiquitous natural phenomenon over the ocean and can be diagnosed by evaporation duct model. The model proposed by Paulus and Jeske and another model established by the American naval postgraduate school are the most widely used. They are called PJ model and NPS model, respectively. Two methods are used to investigate the global sensitivity of PJ model and NPS model in China Seas. The first method is based on meteorological and oceanographic observation data in China Seas. Considering the system random error caused by sensor measurement inaccuracies, the mean relative error and mean absolute error are used as criterion for sensitivity analysis. The second method, called Extended Fourier Amplitude Sensitivity Test(EFAST), takes into account the interaction between input parameters and is used for sensitivity analysis. The results show that NPS model is more sensitive to the random errors of sensors than PJ model. The mean relative errors of PJ model and NPS model are 11.43% and 14.81%, respectively. The results of global sensitivity parameter analysis indicate that wind speed is the key factor of PJ model, while all input parameter of NPS model have relatively large total sensitivity index. In addition, sensitivity analysis results confirm that wind speed is one of main driving factors for the formation of evaporation duct. These results are valuable for the selection of diagnosis models for evaporation duct, the evaluation of radio wave propagation in the marine atmospheric surface layer, and the prediction technique of evaporation duct based on numerical weather prediction(NWP) in China seas.
2019年05期 v.18 1022-1030页 [查看摘要][在线阅读][下载 714K] - SHI Hongda;DONG Xiaochen;FENG Liang;HAN Zhi;
To take advantage of the abundance of both fishery and wave energy resources in offshore sea areas, a novel floating platform with a heaving buoy-based wave energy converter(WEC) assembled with a set of net cages is presented in this work. The floating WEC system provides a power supply, while the net cages are used for aquaculture. It is designed to have an independent and self-operation breeding function. An experimental study is carried out to investigate the hydrodynamic performance of the device in a wave tank considering the factors of net cages, draft depth, and power take-off, and results show that these variables have significant effects on wave energy capture. Incident waves with short periods cause intense interactions that allow the device to undergo large relative motion. The draft depth could be determined according to wave period rather than wave height. This study also explores the response amplitude operator of the device and determines its resonance scope. The experimental results could provide reliable information for future studies on phase differences and the design of two-body WECs.
2019年05期 v.18 1031-1040页 [查看摘要][在线阅读][下载 1357K] - LIU Xiaodong;YUAN Peng;WANG Shujie;YUAN Shuai;TAN Junzhe;SI Xiancai;
The sea area east of Chenshan Cape has peak tidal current flows that exceed 2.3 m s-1, which make it a promising site for the development of tidal current energy. Before these resources can be exploited, a comprehensive assessment is needed of the potential environmental impacts of the extraction of this energy. In this paper, we describe our construction of a three-dimensional hydrodynamic model of the waters near Chengshan Cape, and verify the performance of the model using continuous data measured in situ. We modeled the potential impacts of the exploitation of these resources on the flow field by adding a momentum loss term in the governing equation of the model. Simulation results show that an assumed tidal farm with an estimated power output of 20.34 MW would have a significant impact on the surrounding water level, especially next to the farm, where fluctuation could reach 6 cm. The maximum drop in the flow velocity in the wake of the farm was predicted to be more than 0.8 m s-1, and this influence would extend 10 km downstream.
2019年05期 v.18 1041-1050页 [查看摘要][在线阅读][下载 1810K] - LIU Shubo;WEI Enbo;JIN Xu;LV Ailing;DANG Hongxing;
The wind retrieval performance of HY-2 A scanning scatterometer operating at Ku-band in HH and VV polarizations has been well evaluated in the wind speed range of 0–25 m s-1. In order to obtain more accurate ocean wind field, a potential extension of dual-frequency(C-band and Ku-band) polarimetric measurements is investigated for both low and very high wind speeds, from 5 to 45 m s-1. Based on the geophysical model functions of C-band and Ku-band, the simulation results show that the polarimetric measurements of Ku-band can improve the wind vector retrieval over the entire scatterometer swath, especially in nadir area, with the wind direction root-mean-square error(RMSE) less than 12? in the wind speed range of 5–25 m s-1. Furthermore, the results also show that C-band cross-polarization plays a very important role in improving the wind speed retrieval, with the wind speed retrieval accuracy better than 2 m s-1 for all wind conditions(0–45 m s-1). For extreme winds, the C-band HH backscatter coefficients modeled by CMOD5.N(H) and the ocean co-polarization ratio model at large incidence are used to retrieve sea surface wind vector. This result reveals that there is a big decrease of wind direction retrieval RMSE for extreme wind fields, and the retrieved result of C-band HH polarization is nearly the same as that of C-band VV polarization for low-to-high wind speed(5–25 m s-1). Thus, to improve the wind retrieval for all wind conditions, the dual-frequency polarimetric scatterometer with C-band and Ku-band horizontal polarization in inner beam, and C-band horizontal and Ku-band vertical polarization in outer beam, can be used to measure ocean winds. This study will contribute to the wind retrieval with merged satellites data and the future spaceborne scatterometer.
2019年05期 v.18 1051-1060页 [查看摘要][在线阅读][下载 1345K] - MU Haidi;CHEN Xu;LI Qun;
Laboratory experiments were conducted to investigate the evolution of interfacial internal solitary waves(ISWs) incident on a triangular barrier. ISWs with different amplitudes were generated by gravitational collapse. The ISW energy dissipation and turbulence processes were calculated as waves passed over the triangular barrier. Experimental results showed that ISWs were reflecting back off the triangular barrier, and shoaling ISWs led to wave breaking and mixing when waves propagated over the obstacle. Wave instability created the dissipation of energy as it was transmitted from waves to turbulence. The rate of ISW energy dissipation, the maximum turbulent dissipation, and the buoyancy diffusivity linearly increased with the increase in the incident wave energy.
2019年05期 v.18 1061-1069页 [查看摘要][在线阅读][下载 1264K] - LOU Min;ZHANG Yuansheng;WU Wugang;
The compliant vertical access riser(CVAR) is a new riser concept with good compliance; it can significantly reduce operating costs by eliminating the need for additional machines to operate wells directly on the platform. In this study, we determined the optimal riser parameters in terms of the stress and riser weight by optimizing the CVAR, and we compared the optimization results. A two-dimensional nonlinear static CVAR model was deduced according to the principles of virtual work and variation, and the model was verified using MATLAB. Design of experiments and Kriging method were used to reduce the number of sample calculations and improve the modeling accuracy. An appropriate selection of the multi-objective optimization problem(MOP) and the non-dominated sorting genetic algorithm helped to optimize the CVAR design. The non-dominated sorting genetic algorithm II was used to solve the Pareto frontier of the optimization model in order to provide decision makers with more choices for the optimization results. After optimizing the riser parameters, the geometry of the riser was smoother, and the stress and stress differences were greatly reduced; the maximum equivalent stresses at the top and bottom were reduced by 36.6% and 44%, respectively. In addition, the stress difference in the buoyancy block area was reduced by 20.9%, and the weight of the riser was increased significantly by 28.1%.
2019年05期 v.18 1070-1078页 [查看摘要][在线阅读][下载 1317K] - LI Hongzhi;ZHANG Sai;QIN Xiaocong;ZHANG Xiaoyang;ZHENG Yu;
An expendable conductivity-temperature-depth profiler(XCTD) is one of the most important instruments used to obtain hydrological data, such as temperature and conductivity, and detect ocean depth in a large area. However, the XCTD channel provides poor time-varying performance, narrowband, and low signal-to-noise ratio(SNR), which severely restricts the data transmission rate. In contrast to conventional single-carrier modulation techniques, such as amplitude-shift keying and differential phase-shift keying, this article provides a new method, based on orthogonal frequency division multiplexing(OFDM) to enhance the data transmission rate of deep-sea abandoned profilers. We apply the OFDM to enhance the SNR of the XCTD, which is achieved by reducing the data transmission rate of each sub-channel. Moreover, the bandwidth utilization may be improved by increasing the number of subcarriers in a given bandwidth, which enhances the data transmission rate. Based on analysis of the XCTD channel model, OFDM with different parameters such as constellation mapping, number of subcarriers, subcarrier spacing, signal period and cyclic prefix are achieved. To verify the effectiveness of the OFDM, this study investigates the influence of different parameters on the data transmission rate at different noise levels, i.e.,-20 dB and-40 d B.
2019年05期 v.18 1079-1085页 [查看摘要][在线阅读][下载 854K] - TONG Siyou;WANG Jialin;LI Linwei;ZHANG Haiqi;WU Zhiqiang;SHAO Yulan;
Using a bottom simulating reflector(BSR) on a seismic profile to identify marine gas hydrate is a traditional seismic exploration method. However, owing to the abundance differences between the gas hydrate and free gas in different regions, the BSR may be unremarkable on the seismic profile and invisible in certain cases. With the improvement of exploration precision, difficulty arises in meeting the requirements of distinguishing the abundance differences in the gas hydrate based on BSR. Hence, we studied other sensitive attributes to ascertain the existence of gas hydrate and its abundance variations, eventually improving the success rate of drilling and productivity. In this paper, we analyzed the contradiction between the seismic profile data and drilling sampling data from the Blake Ridge. We extracted different attributes and performed multi-parameter constraint analysis based on the prestack elastic wave impedance inversion. Then, we compared the analysis results with the drilling sampling data. Eventually, we determined five sensitive attributes that can better indicate the existence of gas hydrate and its abundance variations. This method overcomes the limitations of recognizing the gas hydrate methods based on BSR or single inversion attribute. Moreover, the conclusions can notably improve the identification accuracy of marine gas hydrate and provide excellent reference significance for the recognition of marine gas hydrate. Notably, the different geological features of reservoirs feature different sensitivities to the prestacking attributes when using the prestack elastic inversion in different areas.
2019年05期 v.18 1086-1092页 [查看摘要][在线阅读][下载 1710K] - TONG Siyou;CHEN Ming;ZHOU Huawei;LI Linwei;XU Xiugang;WU Zhiqiang;
Ocean-Bottom Node(OBN) acquisitions provide both non-converted and converted reflection energy. There is a clear advantage to independently imaging both P-and S-waves, as they provide more information collectively than either does alone. In many conventional converted-wave pre-stack migration algorithms, density is treated as a constant, which is not the real-life case on earth. S-wave velocity and density information is crucial for hydrocarbon detection because it helps in the identification of porefilling fluids. In this paper, we focused on the effect of density on imaging, and developed a method of reverse-time migration(RTM) on converted s-waves of varying densities(VD-RTMCS). Phase correction was required prior to pre-stack migration to avoid constructive interference between data from adjacent sources. Synthetic data examples showed that when density variations were included, image profiles showed advantages in signal-to-noise ratio, vertical resolution and imaging of complex structures.
2019年05期 v.18 1093-1097页 [查看摘要][在线阅读][下载 861K] - GE Qian;XU Dong;YE Liming;YANG Kehong;YAO Zhigang;
The history of the East Asian monsoon(EAM) since Last Glacial Maximum is reconstructed based on records in a sediment core retrieved from the northern South China Sea. The provenance of organic carbon and the EAM's evolution are investigated using combined organic carbon, grain size, and AMS 14 C dating analysis. Responding to the strong winter monsoon, the marine organic matter was dominated in the sediments, and δ13 C of organic matter was high during the last glacial period. During the Holocene, the primary productivity decreased and the dilution effect of riverine inorganic clastics strengthened. Accordingly, the total organic carbon contents and δ13 C values decreased, and terrestrial organic matter content increased in the core sediments. The 4 μm grain size fraction, as the environmental sensitive grain size component, is determined to reconstruct the paleoclimatic records. During the last glacial period, the contents of 4 μm grain size component were mainly controlled by the sea level changes. Upon the Holocene, the influence of the sea level changes weakened and the roles of current system and provenance strengthened. The correlation between the EAM and solar insolation forcing is also discussed in this paper.
2019年05期 v.18 1098-1104页 [查看摘要][在线阅读][下载 777K] - ZHANG Jinchang;CHEN Jie;HUANG Yanming;
Moho structure provides important clues for understanding crustal structure, isostatic state and magmatic flux from mantle to surface. Across-basin Moho structure of the South China Sea(SCS) is important for understanding crustal evolution mechanisms of both continental break-up and seafloor spreading processes. Southwest Sub-basin(SWSB) opened up the latest and has the closest continental margins, making it the best to study the across-basin structure. Multichannel seismic(MCS) reflection data of line NH973-1 that crosses SWSB in NW-SE direction were reprocessed in order to image Moho structure. In MCS data, Moho reflectors are observed in places, which were not revealed in prior researches. The Moho generally shows symmetric structure on both sides of the central rift valley(CRV) and with variations in crustal thickness. Around CRV, the Moho is 2 seconds depth in two-way travel time(TWTT) beneath the igneous basement, which corresponds to 7 km depth, indicating normal oceanic crustal accretion during the ending of seafloor spreading. Close to the continent-ocean boundary(COB), the Moho becomes shallow to 1 second depth in TWTT(3.5 km), implying strong crustal thinning towards the continent, probably because of poor magma supply at the beginning of seafloor spreading. At south COB, the Moho depth under the crust almost reaches zero, which could be explained as a result of exhumed mantle. In addition, two low-angle, deep-penetrating normal faults are observed at south COB. The faults cut across the Moho into the upper mantle, which may be attributed to lithospheric hyper-stretching at COB during continental break-up.
2019年05期 v.18 1105-1114页 [查看摘要][在线阅读][下载 1533K] - ZHANG Jinchang;CHEN Jie;HUANG Yanming;
Oceanic plateaus are large igneous provinces in the oceans, created by massive underwater eruptions, but their late-stage volcanism is poorly understood. With the addition of recent high-quality bathymetric data to existing data, 286 secondary cones were discovered over Shatsky Rise oceanic plateau. These cones with steeper flank slopes(mean 6.1? ? 4.4?) and smaller sizes(102–1923 m in height) are morphologically distinct from the plateau, and they are thought to have formed after the main volcanic episodes. Cone height and characteristic height(420 m) are close to seamounts in the Pacific Ocean, whereas greater than those in the Atlantic Ocean. Mean flatness of Shatsky Rise's cones(0.25 ? 0.20) are similar to that of seamounts in both Pacific and Atlantic Oceans, but notably density in cone distribution(0.56 km-3) and their mean slope are significantly lower than those of seamounts in the two oceans. Lower slopes of secondary cones within Shatsky Rise may be explained by higher effusion rates of remaining magma. Although cone formation was expected to have a link to rifting by seafloor spreading, weak relationship between cone orientation and magnetic anomaly pattern implies that the expectation is negative. Moreover, weak correlation between the cone height and depth indicates it is not true that volcanic cones grow taller when they occur closer to the massif summits with thicker oceanic crust, which was suggested as the increase in hydraulic pressure. Cone height and flatness are also not strongly related, implying that remaining magma supply was too limited to foster the cones to critical height.
2019年05期 v.18 1115-1122页 [查看摘要][在线阅读][下载 846K] - TIAN Xu;JIANG Zuzhou;GAO Wei;LIU Zhaoqing;LIU Xiling;FAN Ying;QIN Shengjie;JING Chunlei;XU Yue;LIU Baohua;XU Fangjian;
The concentrations of rare earth elements(REEs) in the bulk sediment of Core X2, which was collected from southeastern Hainan Island, were analyzed to investigate the relative contributions of various provenance regions since mid-Holocene. The results show that sediments in Core X2 were primarily derived from Hainan Island with lesser amounts from Taiwan and limited input from the Pearl River. Based on the application of quantitative inversion to model the REE data, the average contributions of river materials from southeastern Hainan Island and southwestern Taiwan to the study area were 68% and 32%, respectively. Furthermore, starting at 4.0 kyr BP, the transport of fluvial sediments from Taiwan to the study region increased due to enhanced hydrodynamics in South China Sea(SCS). These results indicate that the contributions of mountain river materials from Hainan Island and Taiwan to the continental shelf of northern SCS are non-negligible. Furthermore, these results demonstrate that mountain rivers can play an important role in the material cycle of continental margins and may feature a greater impact than large river systems in specific continental shelf areas.
2019年05期 v.18 1123-1129页 [查看摘要][在线阅读][下载 680K] - LIU Jie;YIN Pinghe;ZHAO Ling;
Recently, the widespread use of TiO_2 nanoparticles(nano-TiO_2) has attracted the global concern regarding their adverse effects to aquatic organisms. Nanoparticles may get to the aquatic environments and harm the growth of algae. This paper presents the studies of nano-TiO_2 concentrations influence on the photosynthetic characteristics, antioxidant system and antitumor activity of marine macroalgae Gracilaria lemaneiformis after exposed to 0, 5, 10, 20 or 40 mg L-1 of nano-TiO_2. Results showed that the photosynthetic pigment content of G. lemaneiformis obviously decreased and the antioxidant defense system was significantly disturbed after exposure to nano-TiO_2. Compared with control, the maximum level of malondialdehyde showed 3.3-fold increase for 15 days exposure to nano-TiO_2. The activity of superoxide dismutase and catalase enhanced obviously by 1.10-2.24-fold. The aqueous extract of G. lemaneiformis(AEGL) possesses anticancer activity against HepG2 liver cancer cells proliferation and the 48 h-cell inhibition exceeds 35%. But the toxicity of nano-TiO_2 would inhibit the anticancer activity of AEGL. When G. lemaneiformis was exposed to nano-TiO_2, the effect of the aqueous extract of G. lemaneiformis on the cell inhibition, reactive oxygen species production, apoptosis, cycle arrest of HepG2 cells significantly lessened, and which were linearly associated with nano-TiO_2 exposure concentration. Those results further confirmed that nano-TiO_2 can inhibit the anticancer activity of G. lemaneiformis. The results in this work imply that macroalgae can be an effective biomarker of nano-TiO_2 contaminant, and can be useful indicator to evaluate ecological effects of increasing pollutants in marine ecosystem.
2019年05期 v.18 1130-1138页 [查看摘要][在线阅读][下载 1238K] - WANG Li;YU Liangmin;LIN Cunguo;
Enzyme-based antifouling coatings are potential alternative to traditional tributyltin-based coatings in the marine biofouling control depended on its environmental friendliness. Proteases are usually the key antifouling active components in enzyme based antifouling coatings. In this work, based on biological antagonism effect, a marine proteolytic bacterial strain of Bacillus velezensis was isolated from the sea mud, and denoted as SM-1. The scanning electron microscope(SEM) revealed that the bacteria are rod-shaped with length 1?1.3 μm. The protease-producing conditions of SM-1 were investigated, and it was found that the culture solution displays higher proteolytic activity under the culture conditions of 35℃, 10‰?20‰ salinity, pH 6?9 and more than 7 d culture time. Moreover, the 25 kDa protein was confirmed to be the main active component in the crude protease, which was revealed via the experiment of SDS-PAGE. The antifouling assay indicated that the protease SM-1 has remarkable effect on the decomposition of barnacle cement and diatom secretion, and also can effectively inhibit the attachment of barnacle cyprids, diatom and mussel byssus. Therefore, this protease potentially can be used as environmental-friendly antifoulant of enzyme-based marine antifouling coatings, and this work also provides a new approach to obtain antifouling protease via isolating proteolytic bacteria from the sea mud surrounding representative fouling organisms.
2019年05期 v.18 1139-1146页 [查看摘要][在线阅读][下载 2199K]
- REN Liyuan;LI Kaiquan;ZHAN Yaoyao;WANG Yi;YU Yao;CHEN Yang;LIN Kai;SONG Jian;CHANG Yaqing;
The p21-activated kinase 1(PAK1) is a downstream serine/threonine kinase effector of Rac1/Cdc42 that regulates various biological processes including those associating with pathological inflammation. To investigate the function of PAK1 in echinoderms, we isolated a new PAK1 from sea cucumber Apostichopus japonicus(AjPAK1) by transcriptome database mining and with rapid amplification of cDNA ends(RACE). The full-length cDNA AjPAK1 was 2303 bp in length, containing a 1587 bp ORF encoding 528 amino acid residues. The deduced AjPAK1 contained a p21-Rho-binding domain(PBD) and a serine/threonine protein kinase catalytic domain(S_TKc), which was similar to the PAK1 of crown-of-thorns starfish Acanthaster planci and other eukaryotes. AjPAK1 expressed in all tissues of adult A. japonicus analyzed with the highest transcript anumdance detected in coelomocytes. Significant change in AjPAK1 abundance was observed at 4, 24, 48 and 72 h after Vibrio splendidus infection. Silencing AjPAK1 induced a significant reduction of lysozyme content in coelomic fluid and relative transcript abundances of AjRac1 and AjMKK3/6 in A. japonicus coelomocytes. These results should aid to characterize PAK1 of sea cucumber and decipher its immune function.
2019年05期 v.18 1147-1157页 [查看摘要][在线阅读][下载 1675K] - LU Shaokun;LI Ronghua;GAO Tianlong;WANG Chunlin;ZHENG Weibing;MU Changkao;SONG Weiwei;
In this study, the methylation-sensitive amplification polymorphism(MSAP) was used to compare the genomic DNA methylation level of muscle, gill and hepatopancreas of Portunus trituberculatus subjected to salinity 12 for 30 days to illustrate the epigenetic mechanism of osmoregulation. Thirty primers were used to analyze the difference of methylation level of different tissues. The results showed that the baseline methylation level of muscle, hepatopancreas and gill was 47.31%, 22.94% and 17.69%, respectively. After exposed to low salinity stress, the methylation epiloci changed in the three tissues. Both demethylation and methylation processes occurred under low salinity stress. The methylation ratio decreased in muscle and gill but increased in hepatopancreas. These results indicated that DNA methylation is tissue-specific when P. trituberculatus responds to low salinity.
2019年05期 v.18 1158-1162页 [查看摘要][在线阅读][下载 408K] - CHEN Zhengqiang;ZHANG Dongdong;XING Jing;ZHAN Wenbin;
Bivalve live in aquatic environment and the water temperature can affect their immunity directly. In this research, the scallop Chlamys farreri was injected with 104 or 107 CFU m L-1 Vibrio anguillarum and cultured at 11℃, 17℃, 23℃, and 28℃, respectively. For the control scallop, only phosphate-buffered saline(PBS) was injected. Then total haemocytes and granulocytes were measured by ELISA using monoclonal antibodies. In the meantime, expressions of six immunity-related genes, including lipopolysaccharide and β-1, 3-glucan binding protein(CfLGBP), C-type lectin(CfLec-2), Toll-like receptor(Cf TLR), Lysozyme(CfLYZ), superoxide dismutase(SOD), and phenoloxidase(CfPO) in haemocytes were measured using quantitative real-time PCR. The results showed that total haemocytes counts in 104 CFU m L-1 injection groups showed no differences compared to the control group at all temperatures. However, they varied significantly in 107 CFU m L-1 injection groups at 3 h at 11℃, 6–12 h at 17℃, 3–48 h at 23℃, and 12–48 h at 28℃. Granulocytes counts in 10~4 CFU m L-1 injection groups showed no variance compared to the control group at all temperatures, except for 12 h at 23℃, and 24–36 h at 28℃. They were significantly decreased in 10~7 CFU m L-1 injection groups during 6–48 h at 11℃, 12–48 h at 17℃, 3–48 h at 23℃, and 3–72 h at 28℃. The expression levels of six immunity-related genes in haemocytes of 10~7 CFU m L-1 injection groups were significantly higher than those of control group and 10~4 CFU m L~(-1) injection groups at all temperatures. The results indicated that infected with high concentration of vibrios, haemocyte counts, granulocyte counts and the expressions of immunity-related genes in scallop C. farreri were significantly affected by environmental temperature.
2019年05期 v.18 1163-1173页 [查看摘要][在线阅读][下载 1050K] - MAO Lei;WANG Yiming;WANG Meiling;DAI Yufeng;WANG Jingfeng;XUE Changhu;
The present study investigated the anti-osteoporosis function and the mechanism of sialoglycoproteins isolated from the eggs of Gadus morhua(Gm-SGP) on ovariectomized(OVX) rats. After 3 months of Gm-SGP treatment, OVX-induced bone loss was suppressed and uncoupling bone turnover was balanced, as indicated by systemic biomarkers of bone metabolism; no uterine estrogenicity was observed. Moreover, rats administered with Gm-SGP exhibited increased bone mineral density and biomechanical strength and significant restoration of the trabecular microarchitecture compared with rats in the control group. Gm-SGP significantly decreased bone resorption-related indicators in serum. Investigation of the associated mechanisms revealed that Gm-SGP significantly increases the OPG/RANKL ratio at the mRNA and protein levels. Further research suggested that Gm-SGP inhibits the mRNA and protein expressions of important transcription factors of the MAPK and NF-κB signaling pathways. It also attenuates the activation of related transduction signaling pathways by inhibiting phosphorylation of JNK, ERK, p38, and NF-κB, and ultimately suppresses the induction of c-Fos and NFATc1. Overall, these results demonstrate that Gm-SGP inhibits bone resorption by suppressing osteoclastogenesis-related MAPK and NF-κB pathways, thereby improving osteoporosis.
2019年05期 v.18 1174-1184页 [查看摘要][在线阅读][下载 1101K] - WANG Xiaoqiong;ZHAO Yangguo;WANG Junpeng;ZHANG Mo;BAI Jie;GUO Liang;GAO Mengchun;
To biologically inhibit the production of highly toxic sulfide in the aquaculture area, one bacterium, designated as Hydrogenovibrio thermophilus strain TT, was isolated from sediment in Jiaozhou Bay, China. The strain was found to be microaerobic mixtrophic, employing both carbon dioxide and organic carbons, e.g. citrate, lactate, glucose, and peptone as carbon sources. When it oxidized the sulfide and thiosulfate, oxygen was the optimal electron acceptor, followed by nitrite and nitrate, which benefited to removal of sulfide under low-oxygen mariculture environment. In addition, the strain TT exhibited remarkable tolerance of sulfide and thiosulfate in seawater, and it was able to oxidize 18.52 mmol L~(-1) S~(2-) in 12 h or 45 mmol L~(-1) S_2O_3~(2-) in 24 h at initial pH 7.0-9.0, 30-40℃. Therefore, this strain showed a quite promising application for biological remediation of sulfide-contaminated mariculture system.
2019年05期 v.18 1185-1192页 [查看摘要][在线阅读][下载 761K] - WU Guanzhao;XU Qingliang;BAO Yilei;LIU Yuwei;LI Qian;FANG Zhengyu;FU Jingyi;DING Yuhang;LIANG Zhiqing;JIANG Tao;YU Rilei;
The α7 nicotinic acetylcholine receptors(nAChRs) are widely expressed in the central and peripheral nervous systems and are important drug targets for the treatment of neurological diseases. However, differentiation of the agonists and antagonists of the nAChR is difficult. In this study we aimed to develop a reliable and efficient computational approach for differentiation of the agonists from the antagonists of the nAChR based on a systematical analysis of 123 ligands(87 agonists, 12 partial agonists, and 24 antagonists) binding with the extracellular domain of the α7 n AChR chimera. Our results suggest that the ligand size and ligand binding affinity cannot differentiate the agonists from the antagonists of the nAChR. The ligand efficiency that considers both ligand binding affinity and size for the agonists is overall more left shifted in comparison to the antagonists, but the values of the ligand efficiency still cannot differentiate the agonists from the antagonists unless the values are either relatively high(more than-0.3 kcal mol-1) or relatively low(less than-0.45 kcal mol-1). Our results suggest that accurate prediction of the agonist or antagonist of the nAChR is challenging and the ligand innate configuration has to be considered as an extra for differentiation of the agonists from the antagonists of the nAChR.
2019年05期 v.18 1193-1198页 [查看摘要][在线阅读][下载 784K] - GUO Minrui;CHEN Guogang;CHEN Jiluan;ZHENG Minggang;
The marine microalga Nannochloropsis sp. contains various elongases and desaturases that are critical for biosynthesis of polyunsaturated fatty acids. A full-length cDNA encoding a long-chain fatty acid elongase, named Ns FAE, was cloned from Nannochloropsis sp.. The open reading frame of Ns FAE(GenBank accession no. MF680548) consisted of 1068 bp and encoded a predicted protein of 355 amino acids with molecular mass 38.8 k Da. The deduced polypeptide showed 43%–44% identity to fatty acyl elongases from other algae. RT-PCR experiments indicated that the Ns FAE gene exhibited the highest expression in Nannochloropsis sp. at 72 h(i.e., during the third growth stage) and the expression was significantly lower in the other four growth stages. Plasmid p Ns FAE-CRISPR and a recombinant DNA fragment(ADH1p-Ns FAE-CYCt) were transformed into Saccharomyces cerevisiae strain BY4742 using the CRISPR-Cas system. Yeast transformants containing Ns FAE produced three fatty acids not normally present in wild-type BY4742-linoleic acid, linolenic acid and eicosadienoic acid-indicating that Ns FAE encodes a functional elongase enzyme.
2019年05期 v.18 1199-1206页 [查看摘要][在线阅读][下载 956K] - SONG Lun;WU Jing;DU Jing;LI Nan;WANG Kun;WANG Peng;
Liaodong Bay is one of the largest semi-enclosed bays located in Bohai Sea, in northeast China. It is an important feeding and spawning place, even wintering and breeding migration base for many marine organisms. The size structure of phytoplankton communities is a key feature of marine ecosystems and can be used as an indicator for algae disaster, but the methods to evalute is still challenging. Here, we compared the size-fractionated chlorophyll-a method with a high-throughout sequencing method in an evaluation of the size structure of phytoplankton assemblages in Liaodong Bay, China, in 2014. The proportion of picophytoplankton was estimated at just 19% according to the results based on size-fractionated chlorophyll-a, which likely represents a severe underestimation. The sequencing method confirmed that many kinds of phytoplankton species appeared in more than one size-fractionated filter membrane, with some even dominating where the filter membrane pore size was greater than the individual phytoplankton size. According to the sequencing method, the phytoplankton assemblages in Liaodong Bay were dominated by picophytoplankton(average proportion = 44%), followed by the nanophytoplankton(average 32%), a composition that is more consistent with other studies. The sequencing method provides a more robust way to assess the size structure and taxonomic diversity of marine phytoplankton communities.
2019年05期 v.18 1207-1215页 [查看摘要][在线阅读][下载 770K] - YU Jia;LI Jingyu;WANG Qiaohan;LIU Yan;GONG Qingli;
The abnormal increase of drifting brown alga Sargassum horneri was initially documented in 2007. It formed blooms along the coast of East China Sea and Yellow Sea in 2017. In this study, we investigated the changes of specific growth rate and resource accumulation of drifting S. horneri in response to temperature and nitrogen richness at different growth stages under laboratory condition. The investigation lasted from June 2015 to April 2016 with the observation made every two months. The results showed that the life cycle consists of a few growth stages dividable with morphological characteristics. The growth can be divided into shedding and withering(August), rapid growing(October to September), slow growing(February), rapid growing(April) and maturation(June) stages. Under the experimental condition, algal segments were found to grow at temperatures ranging from 5 to 25℃ in 12 days even when nitrogen is deficient. A significant difference in the special growth rate(SGR) between nitrogen-enriched and nitrogen-removed treatments was found in most months(P < 0.05). SGR was lower in August and February than that in other months. Nitrogen and chlorophyll contents in algal segments were different among different temperatures, nitrogen supply and seasons. Nitrogen content was higher in February and April than that in other months in both nitrogen-enriched and nitrogen-removed treatments. The results showed that the demand of S. horneri for nitrogen increased in spring when it grows fast. It is likely that the high temperature and nitrogen concentration in winter and spring lead to the high biomass accumulation of drifting S. horneri.
2019年05期 v.18 1216-1226页 [查看摘要][在线阅读][下载 782K] - WANG Xinmeng;SUN Peng;TANG Yanli;LIANG Zhenlin;
Chinese government has provided vigorous financial supports to artificial reef(AR) projects to repair marine ecosystem. Qiansandao AR, an important AR project of Fishery Resource Restoration Program in Shandong Province, was built during 2002 to 2007. It has enhanced the local fishery harvest and generated positive economic benefits. Fat greenling(Hexagrammos otakii) is a major commercial reef fish in Qiansandao with high economic values. Its distribution characteristics need to be further studied. In this research, we studied the potential influence of environmental variables and distance from ARs on catch per unit effort(CPUE) and body length of fat greenlings. The results showed that the average body length of fat greenlings distributed within 10 m from ARs was longer than that of fat greenlings distributed more than 600 m away from ARs. Body length also increased with the increased salinity, while it declined as temperature increased. The probability of the presence of fat greenling increased when temperature was below 20℃, then it slightly decreased. CPUE decreased as the distance increased. Our results elucidate the potential effects of environmental variables and distance from ARs on the distribution of fat greenling, which may also be helpful to the distribution research of other reef fish species.
2019年05期 v.18 1227-1234页 [查看摘要][在线阅读][下载 633K] 下载本期数据