Institutional Repository of South China Sea Institute of Oceanology, CAS
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Levels of five metals in male hair from urban and rural areas of Chongqing, China
No full textHeavy metals were measured by flame atomic absorption in male hair from residents in urban and rural areas in Chongqing. The median values of the Cd, Cu, Ni, Pb and Zn were 2.90, 23.9, 9.31, 39.3 and 203 mu g/g in urban areas and 0.84, 13.4, 5.56, 14.5 and 169 mu g/g in rural area, respectively. The levels of Cd, Ni and Pb both in urban and rural areas lie at the high end of the worldwide figures. The differences in heavy metal distribution pattern indicated that there were more sources of Cd and Pb in urban areas. The levels of Cd were increasing along with the growth of age except for the aged people in urban areas, and no significant relationship was observed between the levels of the heavy metal and the age. It is noticed that the hair of smokers exhibited more heavy metal levels than that of non-smokers both in urban and rural areas. In addition, the hair metal levels of the smokers and non-smokers in urban areas were significantly higher than those in rural area, respectively. Significant pairwise correlations (p < 0.01) were observed among Cd, Cu, Ni and Pb in rural area and only between Cu and Ni and between Pb and Ni in urban areas, indicating the elements in these two areas might originate from different sources. The elevated levels of Cd, Pb and Ni implied that the residents both in urban and rural areas might be at high risk of toxic metal exposure, especially for the children
Phenotypic trait of Crassostrea hongkongensis female x C. angulata male hybrids in southern China
No full textThe Hong Kong oyster (Crassostrea hongkongensis) and the Portuguese oyster (Crassostrea angulata) are important aquaculture species in southern China. To understand the potential feasibility of hybridization between the two species, two-by-two factorial cross-experiments were conducted in Shenzhen (Guangdong province). An asymmetry in fertilization was revealed: C. hongkongensis eggs could be fertilized by C. angulata sperm, but the reciprocal cross was not possible. The fertilization and hatching success in the C. hongkongensis females x C. angulata males (HA) cross was lower than the two intraspecific crosses. Moreover, hybrid larvae had a slower growth rate than those from parental progenies due to genome incompatibility. However, the size of the spat and adult growth were greater than those of the two parental progeny, with obvious heterosis during the grow-out stage. The survival advantage of hybrids was examined at all times. The surprising finding was that all hybrids were completely fertile, meaning they could produce normal and functional gametes. Genetic analysis by molecular markers was applied to confirm that the HA spat were true hybrids. Our results revealed that the interspecific hybridization between C. hongkongensis and C. angulata is completely successful in one direction. Furthermore, hybrids are viable, fast growing and completely fertile, which provides a promising method for the genetic improvement of oysters as a new aquaculture stock in southern China
Formation of diploid and triploid hybrid groupers (hybridization of Epinephelus coioides female x Epinephelus lanceolatus male) and their 5S gene analysis
No full textBackground: Interspecies hybridization is widely used to achieve heterosis or hybrid vigor, which has been observed and harnessed by breeders for centuries. Natural allopolyploid hybrids generally exhibit more superior heterosis than both the diploid progenies and their parental species. However, polyploid formation processes have been long ignored, the genetic basis of heterosis in polyploids remains elusive. Results: In the present study, triploid hybrids had been demonstrated to contain two sets of chromosomes from mother species and one set from father species. Cellular polyploidization process in the embryos had been traced. The triploid hybrids might be formed by failure formation of the second polarized genome during the second meiosis stage. Four spindle centers were observed in anaphase stage of the first cell division. Three spindle centers were observed in side of cell plate after the first cell division. The 5S rDNA genes of four types of groupers were cloned and analyzed. The diploid and triploid hybrids had been proved to contain the tandem chimera structures which were recombined by maternal and paternal monomer units. The results indicated that genome re-fusion had occurred in the hybrid progenies. To further elucidate the genetic patterns of diploid and triploid hybrids, fluorescence chromosome location had been carried out, maternal 5S gene (M-386) were used as the probe. The triploid hybrids contained fewer fluorescence loci numbers than the maternal species. The results indicated that participation of paternal 5S gene in the triploid hybrid genome had degraded the match rates of M-386 probe. Conclusions: Our study is the first to investigate the cellular formation processes of natural allopolyploids in hybrid fish, the cellular polyploidization process may be caused by failure formation of the second polarized genome during the meiosis, and our results will provide the molecular basis of hybrid vigor in interspecies hybridization
Crustal thinning and extension in the northwestern continental margin of the South China Sea
No full textMultichannel seismic data on the continental shelf have been used to image the rift-related shallow structural units of the Pearl River Mouth Basin across the northwestern margin of the South China Sea. The Hainan Uplift, Zhu 3 Depression and Shenhu-Ansha Uplift zones are bounded by normal faults or listric-normal faults, which suggest lithospheric extension on the continental shelf. Graben structures10-15km wide are imaged on the Wanshan Uplift and Northern Fault Terrace from the reflection data. The thinned continental crust and anomaly rift-related crust in the depression zone and the transitional crust indicated by the wide-angle OBS velocity model dominate the crustal structure of the continental shelf in the continental margin of the South China Sea. The different total crustal stretching factors in different shallow structural units suggest that non-uniform horizontal stretching controls the crustal thinning. The total crustal stretching factor is ca. 1.4-1.6 at the coast area, ca. 1.67-1.8 in the rift-depression zone and ca. 1.7-1.75 in the transitional crustal domain. Pure-shear crustal thinning controls the crustal extension in the rift-depression zone. The high heat flow anomaly in the vicinity of the seismic lines and anomaly rift-depression velocity structure suggest that the crustal thinning on the continental shelf of the South China Sea can be produced by lateral mantle flow within the hotter regional lithospheric background. Copyright (c) 2015 John Wiley & Sons, Ltd
A Robust but Spurious Pattern of Climate Change in Model Projections over the Tropical Indian Ocean
No full textClimate models consistently project reduced surface warming over the eastern equatorial Indian Ocean (IO) under increased greenhouse gas (GHG) forcing. This IO dipole (IOD)-like warming pattern, regarded as robust based on consistency among models by the new Intergovernmental Panel on Climate Change (IPCC) report, results in a large increase in the frequency of extreme positive IOD (pIOD) events, elevating the risk of climate and weather disasters in the future over IO rim countries. These projections, however, do not consider large model biases in both the mean state and interannual IOD variance. In particular, a "present-future relationship" is identified between the historical simulations and representative concentration pathway (RCP) 8.5 experiments from phase 5 of the Coupled Model Intercomparison Project (CMIP5) multimodel ensemble: models with an excessive IOD amplitude bias tend to project a strong IOD-like warming pattern in themean and a large increase in extreme pIOD occurrences under increased GHG forcing. This relationship links the present simulation errors to future climate projections, and is also consistent with our understanding of Bjerknes ocean-atmosphere feedback. This study calibrates regional climate projections by using this present-future relationship and observed IOD amplitude. The results show that the projected IOD-like pattern of mean changes and frequency increase of extreme pIOD events are largely artifacts of model errors and unlikely to emerge in the future. These results illustrate that a robust projection may still be biased and it is important to consider the model bias effect
Impacts of two types of El Nio on the MJO during boreal winter
No full textThe features of the MJO during two types of El Nio events are investigated in this paper using the daily NCEP-2 reanalysis data, OLR data from NOAA, and Real-time Multivariate MJO index for the period 1979-2012. The results indicate that the MJO exhibits distinct features during eastern Pacific (EP) El Nio events, as compared to central Pacific (CP) El Nio events. First, the intensity of the MJO is weakened during EP El Nio winters from the tropical eastern Indian Ocean to the western Pacific, but enhanced during CP El Nio winters. Second, the range of the MJO eastward propagation is different during the two types of El Nio events. During EP El Nio winters, the MJO propagates eastwards to 120A degrees W, but only to 180A degrees during CP El Nio winters. Finally, the frequency in eight phases of the MJO may be affected by the two types of El Nio. Phases 2 and 3 display a stronger MJO frequency during EP El Nio winters, but phases 4 and 5 during CP El Nio winters
Effect of copper on the performance and bacterial communities of activated sludge using Illumina MiSeq platforms
No full textThe anaerobic-anoxic-aerobic (A(2)O) process is a highly efficient sewage treatment method, which uses complex bacterial communities. However, the effect of copper on this process and the bacterial communities involved remains unknown. In this study, a systematic investigation of the effect of persistent exposure of copper in the A(2)O wastewater treatment system was performed. An A(2)O device was designed to examine the effect of copper on the removal efficiency and microbial community compositions of activated sludge that was continuously treated with 10, 20, and 40 mg L-1 copper, respectively. Surprisingly, a decrease in chemical oxygen demand (COD) and ammonia nitrogen (NH4-N) removal efficiency was observed, and the toxicity of high copper concentration was significantly greater at 7d than at 1d. Proteobacteria, Bacteroidetes, Acidobacteria, Chlorobi, and Nitrospirae were the dominant bacterial taxa in the A(2)O system, and significant changes in microbial community were observed during the exposure period. Most of the dominant bacterial groups were easily susceptible to copper toxicity and diversely changed at different copper concentrations. However, not all the bacterial taxa were inhibited by copper treatment. At high copper concentration, many bacterial species were stimulated and their abundance increased. Cluster analysis and principal coordinate analysis (PCoA) based on operational taxonomic units (OTUs) revealed clear differences in the bacterial communities among the samples. These findings indicated that copper severely affected the performance and key microbial populations in the A(2)O system as well as disturbed the stability of the bacterial communities in the system, thus decreasing the removal efficiency. (C) 2016 Elsevier Ltd. All rights reserved
Characteristics of internal tides in deep water northwest of the Xisha Islands
No full textInternal tides are internal gravity waves with quasi-tidal periodicities, which are ubiquitous in the ocean. Their characteristics in deep water areas between the Hainan Island and Xisha Islands in the northwestern South China Sea (SCS) are investigated based on 5-year moored current observations. The methods used in this study include power spectral analysis, harmonic analysis and dynamical mode decomposition are performed. The results show that the barotropic and baroclinic tidal currents in the study region are both dominated by diurnal oscillations. The vertical isopycnal diurnal displacement can reach 40 m at a depth of 500 similar to 900 m. Diurnal internal tidal currents mainly propagate across the continental slope, approximately 41% of which is phase locked with astronomical tides. The ratio is nearly double of that in the northeast SCS. In the upper ocean, it is found that the variability of internal 01 amplitude is significantly positively correlated with the local sea level height, which suggests a strong modulation by the upper oceanic density field. On the other hand, the Kt internal tid e shows a semi-annual variation with intensification in summer and winter due to the superposition of barotropic forcing from K-1 and P-1 constituents. Furthermore, dynamical mode decomposition shows that the two baroclinic modes together account for more than 70% of O-1 constituent energy, while the contribution of the third mode in the K-1 cannot be neglected, which has 25% of total K-1 energy in someone deployment
Signals of the South China Sea summer rainfall variability in the Indian Ocean
No full textThe present study investigates signals of the South China Sea (SCS) summer rainfall variability in the Indian Ocean. It is found that the SCS summer rainfall has a negative relationship with December-January-February (DJF) western-equatorial Indian Ocean (WIO) sea surface temperature (SST), a positive relationship with an asymmetric mode of precipitation anomalies in the tropical Indian Ocean during March-April-May (MAM), and a positive relationship with June-July-August (JJA) South Indian Ocean (SIO) SST. The WIO SST anomalies induce same-sign southeast Indian Ocean SST anomalies through an anomalous zonal vertical circulation. The southeast Indian Ocean SST anomalies last from late winter to early summer and induce opposite-sign SCS summer rainfall anomalies via an anomalous meridional vertical circulation. The asymmetric mode influences the SCS summer rainfall variation via the North Indian Ocean (NIO) SST anomalies with significant cloud-radiation and wind-evaporation effect. Positive (negative) SIO SST anomalies drive an anomalous direct circulation between the SIO and the NIO, and an anomalous indirect circulation between the NIO and the SCS which facilitates the occurrence of cyclonic (anti-cyclonic) wind anomalies over the SCS-western North Pacific and results in positive (negative) SCS summer rainfall anomalies. Partial correlation analysis indicates that the influence of DJF WIO SST anomalies and JJA SIO SST anomalies on the SCS summer rainfall is partly ENSO-independent, while the MAM asymmetric mode is mostly related to the preceding DJF eastern Pacific SST anomalies
Complete genome sequence of Vibrio alginolyticus ATCC 33787(T) isolated from seawater with three native megaplasmids
No full textVibrio alginolyticus, an opportunistic pathogen, is commonly associated with vibriosis in fish and shellfish and can also cause superficial and ear infections in humans. V. alginolyticus ATCC 33787(T) was originally isolated from sea-water and has been used as one of the type strains for exploring the virulence factors of marine bacteria and for developing vaccine against vibriosis. Here we sequenced and assembled the whole genome of this strain, and identified three megaplasmids and three Type VI secretion systems, thus providing useful information for the study of virulence factors and for the development of vaccine for Vibrio. (C) 2016 Elsevier B.V. All rights reserved