2015 Vol. 37, No. 12
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2015, 37(12): .
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2015, 37(12): 1-10.
doi: 10.3969/j.issn.0253-4193.2015.12.001
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According to the samples taken from the northern South China Sea(17°-24°N,108°-122°E) during 2009 summer and 2010 winter cruise living coccolithophores(LCs) community structure were statistically studied. The LC samples were identified under polarizing microscope,associated with scanning electron microscope(SEM) dealing with the uncertain taxa. A total of 13 taxa belonging to 11 genera were identified. The LCs cell abundance ranged 0.3×103-71.8×103 cells/L in the summer cruise with an average 6.0×103 cells/L,and ranged 0.3×103-64.4×103 cells/L in the winter cruise with an average 6.7×103 cells/L. The Shannon-Wiener index of LCs in summer and winter were ranged from 0.30-1.98 and 0.51-2.25,respectively,and Pielou evenness index were ranged from 0.30-0.99 and 0.33-0.99,respectively. The LCs cell abundance was higher in winter than that in summer. In winter LCs abundance was more prevailing in the deep basin as compared to that in the continental shelf,while in summer it was not in that case. Vertically,high cell abundance of LCs were typically distributed in the sub-surface layer. Umbellosphaera tenuis(Kamptner) Paasche,Emiliania huxleyi(Lohmann) Hay et Mohler and Gephyrocapsa oceanica Kamptner were predominant species in both cruises.E. huxleyi and G. oceanica were positively correlated with the main environmental factors indicated by canonical correspondence analysis(CCA) in summer,nevertheless,the responsing characters varied in winter.
According to the samples taken from the northern South China Sea(17°-24°N,108°-122°E) during 2009 summer and 2010 winter cruise living coccolithophores(LCs) community structure were statistically studied. The LC samples were identified under polarizing microscope,associated with scanning electron microscope(SEM) dealing with the uncertain taxa. A total of 13 taxa belonging to 11 genera were identified. The LCs cell abundance ranged 0.3×103-71.8×103 cells/L in the summer cruise with an average 6.0×103 cells/L,and ranged 0.3×103-64.4×103 cells/L in the winter cruise with an average 6.7×103 cells/L. The Shannon-Wiener index of LCs in summer and winter were ranged from 0.30-1.98 and 0.51-2.25,respectively,and Pielou evenness index were ranged from 0.30-0.99 and 0.33-0.99,respectively. The LCs cell abundance was higher in winter than that in summer. In winter LCs abundance was more prevailing in the deep basin as compared to that in the continental shelf,while in summer it was not in that case. Vertically,high cell abundance of LCs were typically distributed in the sub-surface layer. Umbellosphaera tenuis(Kamptner) Paasche,Emiliania huxleyi(Lohmann) Hay et Mohler and Gephyrocapsa oceanica Kamptner were predominant species in both cruises.E. huxleyi and G. oceanica were positively correlated with the main environmental factors indicated by canonical correspondence analysis(CCA) in summer,nevertheless,the responsing characters varied in winter.
2015, 37(12): 11-18.
doi: 10.3969/j.issn.0253-4193.2015.12.002
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Variability of coccolith downward fluxes and species compositions in sinking particles in the northwestern South China Sea was studied using continuous time-series sediment trap mooring during 2012-2013. Highest coccolith fluxes were found in summer. It was related to the southeast Monsoon induced upwelling off Hainan. Relatively high fluxes were also found in winter,probably correlated to the increased mixed layer depth induced by winter cooling and the northeast Monsoon. Florisphaera profunda was the dominant coccolith species in the sediment traps. Emiliania huxleyi,Gephyrocapsa oceanica and Gephyrocapsa ericsonii were also abundant in the sediment traps. Coccoliths were transferred to coccolithopores,and then Emiliania huxleyi instead of Florisphaera profunda turned to be the prdominant coccolithophore species in the sediment traps. A negative correlation was shown between the relative abundances of Florisphaera profunda and the coccolith fluxes. The close relationship of Florisphaera profunda and the coccolithophore productivity observed by the time-series sediment trap mooring served as a basis to use the relative abundance of Florisphaera profunda as a palaeo-productivity proxy in the palaeoceanography studies in the South China Sea.
Variability of coccolith downward fluxes and species compositions in sinking particles in the northwestern South China Sea was studied using continuous time-series sediment trap mooring during 2012-2013. Highest coccolith fluxes were found in summer. It was related to the southeast Monsoon induced upwelling off Hainan. Relatively high fluxes were also found in winter,probably correlated to the increased mixed layer depth induced by winter cooling and the northeast Monsoon. Florisphaera profunda was the dominant coccolith species in the sediment traps. Emiliania huxleyi,Gephyrocapsa oceanica and Gephyrocapsa ericsonii were also abundant in the sediment traps. Coccoliths were transferred to coccolithopores,and then Emiliania huxleyi instead of Florisphaera profunda turned to be the prdominant coccolithophore species in the sediment traps. A negative correlation was shown between the relative abundances of Florisphaera profunda and the coccolith fluxes. The close relationship of Florisphaera profunda and the coccolithophore productivity observed by the time-series sediment trap mooring served as a basis to use the relative abundance of Florisphaera profunda as a palaeo-productivity proxy in the palaeoceanography studies in the South China Sea.
2015, 37(12): 19-26.
doi: 10.3969/j.issn.0253-4193.2015.12.003
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The sinking particles in the sediment trap can be dissolved to a certain extent due to the chemical dissolution,physical dissolution,extracellular enzyme,etc. This paper studies the dissolution of biogenic particles in the sediment trap located in the deep northern South China Sea in 1987-1988. It could be concluded that the effect of dissolution on the estimation of various fluxes decreased with depth. Overall,the underestimation of particulate organic carbon flux was about 3.8%-40.3%,with an average of 26.6%. The underestimation of particulate nitrogen flux was about 4.2%-76.4%,with an average of 43.7%. There were no relationships between the particle fluxes and the dissolved C and N. But the storing time had significant impact on dissolution of the sinking particles. The sample with longer storing time would have more dissolved quantity.
The sinking particles in the sediment trap can be dissolved to a certain extent due to the chemical dissolution,physical dissolution,extracellular enzyme,etc. This paper studies the dissolution of biogenic particles in the sediment trap located in the deep northern South China Sea in 1987-1988. It could be concluded that the effect of dissolution on the estimation of various fluxes decreased with depth. Overall,the underestimation of particulate organic carbon flux was about 3.8%-40.3%,with an average of 26.6%. The underestimation of particulate nitrogen flux was about 4.2%-76.4%,with an average of 43.7%. There were no relationships between the particle fluxes and the dissolved C and N. But the storing time had significant impact on dissolution of the sinking particles. The sample with longer storing time would have more dissolved quantity.
2015, 37(12): 27-40.
doi: 10.3969/j.issn.0253-4193.2015.12.004
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Multidisciplinary investigations of modern coccolithophores community in the Qiongdong upwelling water of the northern South China Sea(SCS) were performed during the summer cruise of the year 2012. The present study reported the coccolithophores community structure and distribution feature. Total 34 species were identified under polarizing microscope by the filtered membrane samples. The preponderant species were Emiliania huxleyi,Gephyrocapsa oceanica,Umbellosphaera tenuis,Helicosphaera carteri,Coronosphaera mediterranea. Coccolith abundance ranged within 0-2040.23×103 cells/L,with an average value of 8.10×103 cells/L; and coccosphere abundance was 0-68.90×103 cells/L,with an average value of 5.01×103 cells/L. majority of species distributed in the strongly upwelled water. The central area of Qiongdong had larger H' value than that of east of Leizhou Peninsula. The H' and J value of coccolith exhibited mosaic pattern. The results of cluster and MDS showed that coccolith and coccosphere were classified into four groups and five groups respectively,and ANOSIM test proved it to be significant. The redundancy analysis(RDA)indicated that N/P,PO43-,NO2- and SiO32- are the major controlling factors influencing the modern coccolithophore community.
Multidisciplinary investigations of modern coccolithophores community in the Qiongdong upwelling water of the northern South China Sea(SCS) were performed during the summer cruise of the year 2012. The present study reported the coccolithophores community structure and distribution feature. Total 34 species were identified under polarizing microscope by the filtered membrane samples. The preponderant species were Emiliania huxleyi,Gephyrocapsa oceanica,Umbellosphaera tenuis,Helicosphaera carteri,Coronosphaera mediterranea. Coccolith abundance ranged within 0-2040.23×103 cells/L,with an average value of 8.10×103 cells/L; and coccosphere abundance was 0-68.90×103 cells/L,with an average value of 5.01×103 cells/L. majority of species distributed in the strongly upwelled water. The central area of Qiongdong had larger H' value than that of east of Leizhou Peninsula. The H' and J value of coccolith exhibited mosaic pattern. The results of cluster and MDS showed that coccolith and coccosphere were classified into four groups and five groups respectively,and ANOSIM test proved it to be significant. The redundancy analysis(RDA)indicated that N/P,PO43-,NO2- and SiO32- are the major controlling factors influencing the modern coccolithophore community.
2015, 37(12): 41-55.
doi: 10.3969/j.issn.0253-4193.2015.12.005
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The abundance,carbon biomass and distribution of picoplankton were investigated during the summer(August) and winter(February) of 2009 extending from near-shore coastal waters to oligotrophic open waters in northern South China Sea(nSCS). The results showed that the average abundances of Synechococcus(Syn) and Prochlorococcus(Pro) were higher in summer than winter,while Picoeukaryotes(PEuk) and heterotrophic bacteria(HBac) were opposite to Syn and Pro. Syn,PEuk and HBac were most abundant in the eutrophic coast region and continental shelf,while Pro was dominant in the slope and open waters. In vertical profile,the high abundance of Syn mainly appeared above the thermocline and decreased sharply below it. The high Pro abundance in the water column mostly appeared at the bottom of euphotic depth,as well as PEuk. The distribution of HBac was similar to Syn. These different distribution patterns depend on environmental variation and the ecological and physiological adaptation of each group of picoplankton. The contribution of each group of photosynthetic picoplankton biomass varied with the season and sea area:in the summer coastal shelf area,Syn accounted for 41% of total photosynthetic picoplankton biomass; Pro was major contributor(50%) in the slope open waters; while PEuk biomass took 40% higher in winter(reached 68% in the coastal shelf area). And HBac biomass was higher than photosynthetic picoplankton biomass both in the winter and summer.
The abundance,carbon biomass and distribution of picoplankton were investigated during the summer(August) and winter(February) of 2009 extending from near-shore coastal waters to oligotrophic open waters in northern South China Sea(nSCS). The results showed that the average abundances of Synechococcus(Syn) and Prochlorococcus(Pro) were higher in summer than winter,while Picoeukaryotes(PEuk) and heterotrophic bacteria(HBac) were opposite to Syn and Pro. Syn,PEuk and HBac were most abundant in the eutrophic coast region and continental shelf,while Pro was dominant in the slope and open waters. In vertical profile,the high abundance of Syn mainly appeared above the thermocline and decreased sharply below it. The high Pro abundance in the water column mostly appeared at the bottom of euphotic depth,as well as PEuk. The distribution of HBac was similar to Syn. These different distribution patterns depend on environmental variation and the ecological and physiological adaptation of each group of picoplankton. The contribution of each group of photosynthetic picoplankton biomass varied with the season and sea area:in the summer coastal shelf area,Syn accounted for 41% of total photosynthetic picoplankton biomass; Pro was major contributor(50%) in the slope open waters; while PEuk biomass took 40% higher in winter(reached 68% in the coastal shelf area). And HBac biomass was higher than photosynthetic picoplankton biomass both in the winter and summer.
2015, 37(12): 56-65.
doi: 10.3969/j.issn.0253-4193.2015.12.006
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During summer of 2014,an investigation on the abundance and distribution of the three photosynthetic picoplankton groups of Synechococcus(Syn),Prochlorococcus(Pro) and pico-eukaryotes(Euk) in the northern South China Sea and their environmentally regulating mechanisms was carried out using flow cytometry BD Accuri C6. The results show that the average abundances of Syn,Pro and Euk were 5.13×103 cells/mL,3.27×104 cells/mL and 1.85×103 cells/mL,and the average abundances of carbon biomass were 1.19μg/L,1.86μg/L and 4.51μg/L,respectively. The cell abundance of each picoplankton group showed different distribution characteristics. The abundance of Syn,Pro and Euk was high nearshore and low off-shore. The highest abundances of Syn and Euk population both appeared in coast and continental shelf and upwelling waters. The highest abundance of Pro was observed along coast and continental shelf,while the lowest Pro population abundance was observed in upwelling waters. High values of Syn and Euk were mainly found at the surface,while high values of Pro mainly occurred at the bottom of euphotic layer. The variation in Euk distribution was less than those of Syn and Pro. The results of environmental factor correlation analysis indicated close negative correlations between picoplankton carbon biomass and nitrate concentration,silicate concentration and depth,and a significant positive correlation between picoplankton carbon biomass and phosphate concentration.
During summer of 2014,an investigation on the abundance and distribution of the three photosynthetic picoplankton groups of Synechococcus(Syn),Prochlorococcus(Pro) and pico-eukaryotes(Euk) in the northern South China Sea and their environmentally regulating mechanisms was carried out using flow cytometry BD Accuri C6. The results show that the average abundances of Syn,Pro and Euk were 5.13×103 cells/mL,3.27×104 cells/mL and 1.85×103 cells/mL,and the average abundances of carbon biomass were 1.19μg/L,1.86μg/L and 4.51μg/L,respectively. The cell abundance of each picoplankton group showed different distribution characteristics. The abundance of Syn,Pro and Euk was high nearshore and low off-shore. The highest abundances of Syn and Euk population both appeared in coast and continental shelf and upwelling waters. The highest abundance of Pro was observed along coast and continental shelf,while the lowest Pro population abundance was observed in upwelling waters. High values of Syn and Euk were mainly found at the surface,while high values of Pro mainly occurred at the bottom of euphotic layer. The variation in Euk distribution was less than those of Syn and Pro. The results of environmental factor correlation analysis indicated close negative correlations between picoplankton carbon biomass and nitrate concentration,silicate concentration and depth,and a significant positive correlation between picoplankton carbon biomass and phosphate concentration.
2015, 37(12): 66-73.
doi: 10.3969/j.issn.0253-4193.2015.12.007
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A series of laboratory experiments are performed in a wave flume to investigate the wave transformation around the surf zone over fringing reefs. Experimental results are reported for four reef-flat submergences,four fore-reef slopes and a variety of regular wave conditions using an idealized fringing reef model. The surfzone width,as well as the wave incidence,reflection,transmission and energy dissipation around the surf zone are measured,and the effects of higher harmonics are considered to evaluate the transmission coefficient on the reef flat. Data analysis shows that the ratio of reef-flat submergence to deep-water wave height,i.e.,the relative reef-flat submergence,is a key factor to control the wave transformation around the surf zone over fringing reefs,however the influence of fore-reef slope is negligible within the test range. The sufzone width is comparable with shallow-water wave length on the reef flat and it increases with decreasing of relative reef-flat submergence. The transmitted coefficient increases almost linearly with increasing relative reef-flat submergence but such trend could not be found for the reflection coefficient. More than 50% of incident wave energy can be damped by the fringing reef,and larger energy dissipation occurs at a lower relative reef-flat submergence.
A series of laboratory experiments are performed in a wave flume to investigate the wave transformation around the surf zone over fringing reefs. Experimental results are reported for four reef-flat submergences,four fore-reef slopes and a variety of regular wave conditions using an idealized fringing reef model. The surfzone width,as well as the wave incidence,reflection,transmission and energy dissipation around the surf zone are measured,and the effects of higher harmonics are considered to evaluate the transmission coefficient on the reef flat. Data analysis shows that the ratio of reef-flat submergence to deep-water wave height,i.e.,the relative reef-flat submergence,is a key factor to control the wave transformation around the surf zone over fringing reefs,however the influence of fore-reef slope is negligible within the test range. The sufzone width is comparable with shallow-water wave length on the reef flat and it increases with decreasing of relative reef-flat submergence. The transmitted coefficient increases almost linearly with increasing relative reef-flat submergence but such trend could not be found for the reflection coefficient. More than 50% of incident wave energy can be damped by the fringing reef,and larger energy dissipation occurs at a lower relative reef-flat submergence.
2015, 37(12): 74-84.
doi: 10.3969/j.issn.0253-4193.2015.12.008
Abstract:
To better understand carbon and particle dynamics in the Prydz Bay and its adjacent areas,stable carbon isotopic composition in suspended particulate organic matter(POM) along with aqueous CO2,nutrients and hydrographic data were measured to examine the spatial and vertical distributions of δ13CPOC and their controlling factors during the 29th Chinese Antarctic Research Expedition. Furthermore,carbon isotope fractionation factor during the assimilation of dissolved inorganic carbon(DIC) by phytoplankton in the mixed layer was estimated. Our results showed that δ13CPOC ranged from-28.5‰ to-21.1‰ with an average of-24.6‰,showing an increase trend from the inner bay to open waters outside the Bay. Carbon isotope fractionation factor during phytoplankton DIC assimilation in the mixed layer was estimated to be 23.4‰ based on the relationship between δ13CPOC and 1/[CO2(aq)],and was the major controlling factor for δ13CPOC values in the mixed layer in the Prydz Bay and its adjacent areas. Values of δ13CPOC increased in general with increasing depth in the study areas,ascribing to the isotope fractionation during POM remineralization.
To better understand carbon and particle dynamics in the Prydz Bay and its adjacent areas,stable carbon isotopic composition in suspended particulate organic matter(POM) along with aqueous CO2,nutrients and hydrographic data were measured to examine the spatial and vertical distributions of δ13CPOC and their controlling factors during the 29th Chinese Antarctic Research Expedition. Furthermore,carbon isotope fractionation factor during the assimilation of dissolved inorganic carbon(DIC) by phytoplankton in the mixed layer was estimated. Our results showed that δ13CPOC ranged from-28.5‰ to-21.1‰ with an average of-24.6‰,showing an increase trend from the inner bay to open waters outside the Bay. Carbon isotope fractionation factor during phytoplankton DIC assimilation in the mixed layer was estimated to be 23.4‰ based on the relationship between δ13CPOC and 1/[CO2(aq)],and was the major controlling factor for δ13CPOC values in the mixed layer in the Prydz Bay and its adjacent areas. Values of δ13CPOC increased in general with increasing depth in the study areas,ascribing to the isotope fractionation during POM remineralization.
2015, 37(12): 85-92.
doi: 10.3969/j.issn.0253-4193.2015.12.009
Abstract:
Carbon stable isotope ratio(δ13C) has been regarded as an important factor tracing the organic material sources in marine ecosystem. Prior to analysis,samples have to be decarbonated. Inorganic carbon content and component are different in different marine sediments,and appropriate decarbonate methods should be chosen to get exact results. This study compared the effects of three acid treatments on δ13C values during the decarbonation of estuarial and bay sediments with different inorganic carbon content. The results showed that for the first method(rinse method),6% H2SO3 and 1 mol/L H3PO4 could not remove inorganic carbon in high inorganic carbon content samples collecting from tropical estuarial and bay completely,while 2 mol/L HCl could remove inorganic carbon in all marine sediments completely. The second method(fumigation method) is not suitable for sediment samples with high inorganic carbon content from tropical estuarial and bay,but could be used for sediments with lower inorganic carbon content,and it showed that 9 h is the best fumigate time. δ13C values obtained from the third method(non-capsule method) showed more positive values compared to the other two methods,indicated that the third method did not damage the 13C enriched materials. Also the residual acid showed not impact the δ13C values in the third method. The third method is confirmed as the most appropriate acid treatment for decarbonation of marine sediments.
Carbon stable isotope ratio(δ13C) has been regarded as an important factor tracing the organic material sources in marine ecosystem. Prior to analysis,samples have to be decarbonated. Inorganic carbon content and component are different in different marine sediments,and appropriate decarbonate methods should be chosen to get exact results. This study compared the effects of three acid treatments on δ13C values during the decarbonation of estuarial and bay sediments with different inorganic carbon content. The results showed that for the first method(rinse method),6% H2SO3 and 1 mol/L H3PO4 could not remove inorganic carbon in high inorganic carbon content samples collecting from tropical estuarial and bay completely,while 2 mol/L HCl could remove inorganic carbon in all marine sediments completely. The second method(fumigation method) is not suitable for sediment samples with high inorganic carbon content from tropical estuarial and bay,but could be used for sediments with lower inorganic carbon content,and it showed that 9 h is the best fumigate time. δ13C values obtained from the third method(non-capsule method) showed more positive values compared to the other two methods,indicated that the third method did not damage the 13C enriched materials. Also the residual acid showed not impact the δ13C values in the third method. The third method is confirmed as the most appropriate acid treatment for decarbonation of marine sediments.
2015, 37(12): 93-105.
doi: 10.3969/j.issn.0253-4193.2015.12.010
Abstract:
The evident and distinctive vulnerability is the characteristics of island ecosystem,and poses a threat to ecological environment and social-economic development on island. It is the fundamental premise for maintaining island ecosystem and wise island utilization to accurately grasp and effectively control the island ecological vulnerability(IEV),and a set of scientific,unified and targeted conceptual system is the basis of IEV research. In view of the particularity of island ecosystem,related researched were based on,Chinese islands were paid more emphasis on,and a large number of typical cases of islands were analyzed to establish the conceptual system composed of connotation,features and causes. The connotation of IEV was proposed to be the vulnerability to damage and difficulty of restoration of island ecosystem under the unique conditions and various disturbances,and long-term,heterogeneity and controllability were the typical features of IEV. The special location,limited area and isolated space of island ecosystem made itself have both oceanic and terrestrial property,as well as resource-scarcity,independence and completeness,which were interacted with different kinds and degrees of natural and human disturbances and leaded to the occurrence and aggravation of IEV. The conceptual system can provide a practical foundation for deep analysis and rational control of IEV.
The evident and distinctive vulnerability is the characteristics of island ecosystem,and poses a threat to ecological environment and social-economic development on island. It is the fundamental premise for maintaining island ecosystem and wise island utilization to accurately grasp and effectively control the island ecological vulnerability(IEV),and a set of scientific,unified and targeted conceptual system is the basis of IEV research. In view of the particularity of island ecosystem,related researched were based on,Chinese islands were paid more emphasis on,and a large number of typical cases of islands were analyzed to establish the conceptual system composed of connotation,features and causes. The connotation of IEV was proposed to be the vulnerability to damage and difficulty of restoration of island ecosystem under the unique conditions and various disturbances,and long-term,heterogeneity and controllability were the typical features of IEV. The special location,limited area and isolated space of island ecosystem made itself have both oceanic and terrestrial property,as well as resource-scarcity,independence and completeness,which were interacted with different kinds and degrees of natural and human disturbances and leaded to the occurrence and aggravation of IEV. The conceptual system can provide a practical foundation for deep analysis and rational control of IEV.
2015, 37(12): 106-115.
doi: 10.3969/j.issn.0253-4193.2015.12.011
Abstract:
Tg-HbⅡ(heterogeneous tetramer) and Tg-HbⅠ(homodimer) were purified by gel chromatography with a recovery 48.15% and 24.91%. Seven major peptides(F1-F7) were purified by reverse phase C-18 column from trysin enzymatic hydrolysates of Tg-HbⅡ. The agar diffusion method was used to detect their antibacterial activity. Results showed that all peptide collections exhibited no antibacterial activity to Staphylococcus aureus,Pseudomonas putida,Eschetichia coli,Bacillus firmus and B. subtilis; but peptides F2-F7 showed antibacterial activity against Vibrio alginolyticus,V. harveyi and V. parahaemolyticus. MICs of peptide F2-F7 toward V. alginolyticus,V. parahaemolyticus and V. harveyi were 0.012-0.200 mg/mL Using fluorescence microscopy to observe the cell that treated with peptide,found that vibrio cells die rapidly in 5 min. Using Transmission electron microscopy to observe V. alginolyticus and V. harveryi after antibacterial peptides treatment,the results showed that the peptides changed permeability of cytoplasmic membrane,leading to leaking out of cytoplasmic contents. Finally,the affected Vibrio died due to leakage of the cell contents. Research results showed that the Tegillarca granosa hemoglobin source of antimicrobial peptides have obvious antibacterial activity against vibrio and antimicrobial peptides kill bacteria by damaging its internal structure,these findings laid a solid foundation to the research of antibacterial mechanism of hemoglobin.
Tg-HbⅡ(heterogeneous tetramer) and Tg-HbⅠ(homodimer) were purified by gel chromatography with a recovery 48.15% and 24.91%. Seven major peptides(F1-F7) were purified by reverse phase C-18 column from trysin enzymatic hydrolysates of Tg-HbⅡ. The agar diffusion method was used to detect their antibacterial activity. Results showed that all peptide collections exhibited no antibacterial activity to Staphylococcus aureus,Pseudomonas putida,Eschetichia coli,Bacillus firmus and B. subtilis; but peptides F2-F7 showed antibacterial activity against Vibrio alginolyticus,V. harveyi and V. parahaemolyticus. MICs of peptide F2-F7 toward V. alginolyticus,V. parahaemolyticus and V. harveyi were 0.012-0.200 mg/mL Using fluorescence microscopy to observe the cell that treated with peptide,found that vibrio cells die rapidly in 5 min. Using Transmission electron microscopy to observe V. alginolyticus and V. harveryi after antibacterial peptides treatment,the results showed that the peptides changed permeability of cytoplasmic membrane,leading to leaking out of cytoplasmic contents. Finally,the affected Vibrio died due to leakage of the cell contents. Research results showed that the Tegillarca granosa hemoglobin source of antimicrobial peptides have obvious antibacterial activity against vibrio and antimicrobial peptides kill bacteria by damaging its internal structure,these findings laid a solid foundation to the research of antibacterial mechanism of hemoglobin.
2015, 37(12): 116-122.
doi: 10.3969/j.issn.0253-4193.2015.12.012
Abstract:
In this study,the impact of ocean acidification on the skeletal development in embryonic marine medaka was investigated. The seawater carbonate system in the water was maintained stable by aerating with ambient air(450×10-6 CO2) and CO2-enriched air(1160×10-6 or 1783×10-6 CO2). Newly fertilized medaka eggs were exposed to three levels of pCO2/pH(8.14,7.85 and 7.67) until to the main hatch occurring. Skeletons of 30 new-hatched larvae from each CO2 treatment were cleared,stained and photographed. Lengths of well stained 28 skeletal elements for ecah fish was measured using digital photograph and analyzed by image analysis software. Results showed that,the effects of exposure to elevated CO2 concentrations on the length of representative skeletal elements were not significant. It suggested that the skeletal development of marine medaka would not be seriously affected by the changes in CO2 concentrations that are predicted to occur over the next 100 to 200 years.
In this study,the impact of ocean acidification on the skeletal development in embryonic marine medaka was investigated. The seawater carbonate system in the water was maintained stable by aerating with ambient air(450×10-6 CO2) and CO2-enriched air(1160×10-6 or 1783×10-6 CO2). Newly fertilized medaka eggs were exposed to three levels of pCO2/pH(8.14,7.85 and 7.67) until to the main hatch occurring. Skeletons of 30 new-hatched larvae from each CO2 treatment were cleared,stained and photographed. Lengths of well stained 28 skeletal elements for ecah fish was measured using digital photograph and analyzed by image analysis software. Results showed that,the effects of exposure to elevated CO2 concentrations on the length of representative skeletal elements were not significant. It suggested that the skeletal development of marine medaka would not be seriously affected by the changes in CO2 concentrations that are predicted to occur over the next 100 to 200 years.
2015, 37(12): 123-128.
doi: 10.3969/j.issn.0253-4193.2015.12.013
Abstract:
To study antibiotic resistance pattern and resistant gene of Escherichia coli from seawater recreational beach,41E.coli isolates from seawater in Dalian Xinghai bathing beach were identified and characterized using biochemical tests. Antimicrobial resistance of E.coli isolates was determined by Kirby-Bauer disk diffusion method,the result showed highest resistance to tetracycline(46%) and lowest resistance against ammonia QuNa(5%). Multidrug resistance was observed in 34% of 41E.coli isolates. Only tetracycline resistant gene tetA and tetB gene were detected among the 41 isolates using PCR method. The detection frequency of tetA gene was 34% in genome DNA and 29% in plasmid DNA of E.coli. While tetB gene was detected in 2% of E.coli genome DNA and in 12% of E.coli plasmid DNA. χ2test suggest that tetracycline resistant phenotype of E.coli is correlated with tetracycline resistant gene.
To study antibiotic resistance pattern and resistant gene of Escherichia coli from seawater recreational beach,41E.coli isolates from seawater in Dalian Xinghai bathing beach were identified and characterized using biochemical tests. Antimicrobial resistance of E.coli isolates was determined by Kirby-Bauer disk diffusion method,the result showed highest resistance to tetracycline(46%) and lowest resistance against ammonia QuNa(5%). Multidrug resistance was observed in 34% of 41E.coli isolates. Only tetracycline resistant gene tetA and tetB gene were detected among the 41 isolates using PCR method. The detection frequency of tetA gene was 34% in genome DNA and 29% in plasmid DNA of E.coli. While tetB gene was detected in 2% of E.coli genome DNA and in 12% of E.coli plasmid DNA. χ2test suggest that tetracycline resistant phenotype of E.coli is correlated with tetracycline resistant gene.
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