Cyanobacterial blooms occur in eutrophic lakes worldwide, and greatly impair these ecosystems. To explore influences of cyanobacterial blooms on dynamics of both particulate organic matter(POM) and dissolved organic m...Cyanobacterial blooms occur in eutrophic lakes worldwide, and greatly impair these ecosystems. To explore influences of cyanobacterial blooms on dynamics of both particulate organic matter(POM) and dissolved organic matter(DOM), which are at the base of the food chain, an investigation was conducted from December 2014 to November 2015 that included various stages of the seasonal cyanobacterial blooms(dominated by M icrocystis) in a large-shallow eutrophic Chinese lake(Taihu Lake). Data from eight sites of the lake are compiled into a representative seasonal cycle to assess general patterns of POM and DOM dynamics. Compared to December, 5-fold and 3.5-fold increases were observed in July for particulate organic carbon(POC, 3.05–15.37 mg/L) and dissolved organic carbon(DOC, 5.48–19.25 mg/L), respectively, with chlorophyll a(Chl a) concentrations varying from 8.2 to 97.7 μg/L. Approximately 40% to 76% of total organic carbon was partitioned into DOC. All C, N, and P in POM and DOC were significantly correlated with Chl a. POC:Chl a ratios were low, whereas proportions of the estimated phytoplankton-derived organic matter in total POM were high during bloom seasons. These results suggested that contributions of cyanobacterial blooms to POM and DOC varied seasonally. Seasonal average C:P ratios in POM and DOM varied from 79 to 187 and 299 to 2 175, respectively. Both peaked in July and then sharply decreased. Redundancy analysis revealed that Chl a explained most of the variations of C:N:P ratios in POM, whereas temperature was the most explanatory factor for DOM. These findings suggest that dense cyanobacterial blooms caused both C-rich POM and DOM, thereby providing clues for understanding their influence on ecosystems.展开更多
The ubiquitin-proteasome system plays a pivotal role in breast tumorigenesis by controlling transcription factors, thus promoting cell cycle growth, and degradation of tumor suppressor proteins. However, breast cancer...The ubiquitin-proteasome system plays a pivotal role in breast tumorigenesis by controlling transcription factors, thus promoting cell cycle growth, and degradation of tumor suppressor proteins. However, breast cancer patients have failed to benefit from proteasome inhibitor treatment partially due to proteasome heterogeneity, which is poorly understood in malignant breast neoplasm. Chemical crosslinking is an increasingly important tool for mapping protein three-dimensional structures and proteinprotein interactions. In the present study, two cross-linkers, bis（sulfosuccinimidyl） suberate（BS3） and its water-insoluble analog disuccinimidyl suberate（DSS）, were used to map the subunit-subunit interactions in 20 S proteasome core particle（CP） from MDA-MB-231 cells. Different types of gel electrophoresis technologies were used. In combination with chemical cross-linking and mass spectrometry, we applied these gel electrophoresis technologies to the study of the noncovalent interactions among 20 S proteasome subunits. Firstly, the CP subunit isoforms were profiled. Subsequently, using native/SDSPAGE, it was observed that 0.5 mmol/L BS^3 was a relatively optimal cross-linking concentration for CP subunit-subunit interaction study. 2-DE analysis of the cross-linked CP revealed that α1 might preinteract with α2, and α3 might pre-interact with α4. Moreover, there were different subtypes of α1α2 and α3α4 due to proteasome heterogeneity. There was no significant difference in cross-linking pattern for CP subunits between BS3 and DSS. Taken together, the gel-based characterization in combination with chemical cross-linking could serve as a tool for the study of subunit interactions within a multi-subunit protein complex. The heterogeneity of 20 S proteasome subunit observed in breast cancer cells may provide some key information for proteasome inhibition strategy.展开更多
基金Supported by the Natural Science Foundation of Jiangsu Province,China(No.BK20131466)the National Natural Science Foundation of China(Nos.31370509,31100363)the Start-up Funds from Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences(No.NIGLAS2011QD05)
文摘Cyanobacterial blooms occur in eutrophic lakes worldwide, and greatly impair these ecosystems. To explore influences of cyanobacterial blooms on dynamics of both particulate organic matter(POM) and dissolved organic matter(DOM), which are at the base of the food chain, an investigation was conducted from December 2014 to November 2015 that included various stages of the seasonal cyanobacterial blooms(dominated by M icrocystis) in a large-shallow eutrophic Chinese lake(Taihu Lake). Data from eight sites of the lake are compiled into a representative seasonal cycle to assess general patterns of POM and DOM dynamics. Compared to December, 5-fold and 3.5-fold increases were observed in July for particulate organic carbon(POC, 3.05–15.37 mg/L) and dissolved organic carbon(DOC, 5.48–19.25 mg/L), respectively, with chlorophyll a(Chl a) concentrations varying from 8.2 to 97.7 μg/L. Approximately 40% to 76% of total organic carbon was partitioned into DOC. All C, N, and P in POM and DOC were significantly correlated with Chl a. POC:Chl a ratios were low, whereas proportions of the estimated phytoplankton-derived organic matter in total POM were high during bloom seasons. These results suggested that contributions of cyanobacterial blooms to POM and DOC varied seasonally. Seasonal average C:P ratios in POM and DOM varied from 79 to 187 and 299 to 2 175, respectively. Both peaked in July and then sharply decreased. Redundancy analysis revealed that Chl a explained most of the variations of C:N:P ratios in POM, whereas temperature was the most explanatory factor for DOM. These findings suggest that dense cyanobacterial blooms caused both C-rich POM and DOM, thereby providing clues for understanding their influence on ecosystems.
基金supported by the National Natural Science Foundation of China(No.81202095)the Research Fund for the Doctoral Program of Higher Education of China(No.20120142120053)the Hubei Provincial Natural Science Foundation of China(No.2013CFB134)
文摘The ubiquitin-proteasome system plays a pivotal role in breast tumorigenesis by controlling transcription factors, thus promoting cell cycle growth, and degradation of tumor suppressor proteins. However, breast cancer patients have failed to benefit from proteasome inhibitor treatment partially due to proteasome heterogeneity, which is poorly understood in malignant breast neoplasm. Chemical crosslinking is an increasingly important tool for mapping protein three-dimensional structures and proteinprotein interactions. In the present study, two cross-linkers, bis（sulfosuccinimidyl） suberate（BS3） and its water-insoluble analog disuccinimidyl suberate（DSS）, were used to map the subunit-subunit interactions in 20 S proteasome core particle（CP） from MDA-MB-231 cells. Different types of gel electrophoresis technologies were used. In combination with chemical cross-linking and mass spectrometry, we applied these gel electrophoresis technologies to the study of the noncovalent interactions among 20 S proteasome subunits. Firstly, the CP subunit isoforms were profiled. Subsequently, using native/SDSPAGE, it was observed that 0.5 mmol/L BS^3 was a relatively optimal cross-linking concentration for CP subunit-subunit interaction study. 2-DE analysis of the cross-linked CP revealed that α1 might preinteract with α2, and α3 might pre-interact with α4. Moreover, there were different subtypes of α1α2 and α3α4 due to proteasome heterogeneity. There was no significant difference in cross-linking pattern for CP subunits between BS3 and DSS. Taken together, the gel-based characterization in combination with chemical cross-linking could serve as a tool for the study of subunit interactions within a multi-subunit protein complex. The heterogeneity of 20 S proteasome subunit observed in breast cancer cells may provide some key information for proteasome inhibition strategy.
