Coral fluorescence phenotypes have been suggested as an adaptation to a broad range of environmental conditions,yet the mechanisms linking thermal bleaching tolerance in reef-building coral populations,associated with...Coral fluorescence phenotypes have been suggested as an adaptation to a broad range of environmental conditions,yet the mechanisms linking thermal bleaching tolerance in reef-building coral populations,associated with fluorescence phenotypes due to GFP-like proteins,remains unclear.In this study,the relationship between the thermal sensitivity and phenotypic plasticity of corals was investigated using two phenotypes of Galaxea fascicularis,green and brown.The results reveal that brown G.fascicularis was more susceptible to bleaching than green G.fascicularis when exposed to a higher growth temperature of 32℃.Both phenotypes of G.fascicularis were associated with the thermotolerant Symbiodiniaceae symbiont,Durusdinium trenchii.However,the brown G.fascicularis showed a significant decrease in Symbiodiniaceae cell density and a significant increase in pathogenic bacteria abundance when the growth temperature was raised from 29 to 32℃.The physiological traits and transcriptomic profiles of Symbiodiniaceae were not notably affected,but there were differences in the transcriptional levels of certain genes between the two phenotype hosts of G.fascicularis.Under heat stress of 32℃,the gene encoding green fluorescent protein(GFP)-like and chromosome-associated proteins,as well as genes related to oxidative phosphorylation,cell growth and death showed lower transcriptional levels in the brown G.fascicularis compared to the green G.fascicularis.Overall,the results demonstrate that the green form of G.fascicularis is better able to tolerate ocean warming and defend against pathogenic bacteria,likely due to higher gene transcription levels and defense ability.展开更多
Scleractinian corals host numerous microbial symbionts with different types of interactions. The gastric cavity of scleractinian coral, as a semiclosed subenvironment with distinct chemical characteristics(e.g., disso...Scleractinian corals host numerous microbial symbionts with different types of interactions. The gastric cavity of scleractinian coral, as a semiclosed subenvironment with distinct chemical characteristics(e.g., dissolved O2, pH, alkalinity, and nutrients), harbors a distinct microbial community and a diverse array of bacteria that can be pathogenic or beneficial. Galaxea fascicularis is one of the dominant massive scleractinian coral species on inshore fringing reefs in the northern South China Sea.Although the abundance of coral-associated bacteria has been investigated in G. fascicularis, less is known about the microorganisms in the gastric cavity. In this study, we specially isolated cultivable bacterial strains from the gastric cavity of G.fascicularis collected from Hainan Island using a noninvasive sampling approach. Among the 101 representative bacterial strains, one Vibrio coralliilyticus strain, SCSIO 43001, was found to be a temperature-dependent opportunistic pathogen of G.fascicularis. The antagonistic activity between the 100 strains and V. coralliilyticus SCSIO 43001 was tested using a modified Burkholder diffusion assay. Our results showed that V. coralliilyticus SCSIO 43001 inhibits the growth of Erythrobacter flavus and Sphingomonas yabuuchiae. Additionally, we found that three Pseudoalteromonas strains showed moderate to high antibacterial activity against V. coralliilyticus SCSIO 43001 and several other coral-associated Gram-negative bacterial strains.These results suggest that competition between the coral pathogen and other bacteria also occurs in the gastric cavity of coral, and Pseudoalteromonas strains in the gastric cavity of G. fascicularis may provide a protective role in the defense against coinhabiting coral pathogens at elevated temperature.展开更多
Nitrogen cycle is critical to maintain a healthy coral reef ecosystem.Urea can provide a source of nitrogen for coral holobiont and is important for coral calcification through degradation by urease.Despite the involv...Nitrogen cycle is critical to maintain a healthy coral reef ecosystem.Urea can provide a source of nitrogen for coral holobiont and is important for coral calcification through degradation by urease.Despite the involvement of coral-associated bacteria in nitrogen fixation,nitrification and denitrification are well recognized,to what extend urea degradation by bacteria contributing to the urea utilization by coral holobiont remains to be investigated.In this study,we demonstrate that the urea utilization is a common feature of Halomonas spp.that is a dominant genus in cultivable coral-associated bacteria.A urease operon was characterized by genome sequencing and gene knock-out technique in Halomonas meridiana SCSIO 43005,isolated from the gastric cavity of healthy scleractinian coral Galaxea fascicularis.H.meridiana showed high urease activity which was induced by urea and deletion of the urease operon reduced the capability to use urea as solo nitrogen source.Furthermore,approximately 1/3 coral-associated bacteria in the IMG/M database possess complete urease operons indicating the involvement of bacteria-derived ureases in coral holobiont.These results suggest that urease from coral-associated bacteria might be important player in the nitrogen cycling of coral reefs.展开更多
基金supported by the Opening Project of Guangxi Laboratory on the Study of Coral Reefs in the South China Sea,Nanning 530004,China(GXLSCRSCS2019003)Natural Science Foundation of Guang Dong(2022A1515010521)+2 种基金the National Natural Science Foundation of China(31971501)The CAS Pioneer Hundred Talents Program(Y8SL031001,Y9YB021001)Science and Technology Program of Guangzhou,China(202002030345).
文摘Coral fluorescence phenotypes have been suggested as an adaptation to a broad range of environmental conditions,yet the mechanisms linking thermal bleaching tolerance in reef-building coral populations,associated with fluorescence phenotypes due to GFP-like proteins,remains unclear.In this study,the relationship between the thermal sensitivity and phenotypic plasticity of corals was investigated using two phenotypes of Galaxea fascicularis,green and brown.The results reveal that brown G.fascicularis was more susceptible to bleaching than green G.fascicularis when exposed to a higher growth temperature of 32℃.Both phenotypes of G.fascicularis were associated with the thermotolerant Symbiodiniaceae symbiont,Durusdinium trenchii.However,the brown G.fascicularis showed a significant decrease in Symbiodiniaceae cell density and a significant increase in pathogenic bacteria abundance when the growth temperature was raised from 29 to 32℃.The physiological traits and transcriptomic profiles of Symbiodiniaceae were not notably affected,but there were differences in the transcriptional levels of certain genes between the two phenotype hosts of G.fascicularis.Under heat stress of 32℃,the gene encoding green fluorescent protein(GFP)-like and chromosome-associated proteins,as well as genes related to oxidative phosphorylation,cell growth and death showed lower transcriptional levels in the brown G.fascicularis compared to the green G.fascicularis.Overall,the results demonstrate that the green form of G.fascicularis is better able to tolerate ocean warming and defend against pathogenic bacteria,likely due to higher gene transcription levels and defense ability.
基金supported by the National Key R & D Program of China (Grant Nos. 2018YFC1406500 & 2017YFC0506303)the National Natural Science Foundation of China (Grant Nos. 41706172, 31625001 & 41376174)the Hainan Provincial Key R & D (Grant No. ZDYF2018108)
文摘Scleractinian corals host numerous microbial symbionts with different types of interactions. The gastric cavity of scleractinian coral, as a semiclosed subenvironment with distinct chemical characteristics(e.g., dissolved O2, pH, alkalinity, and nutrients), harbors a distinct microbial community and a diverse array of bacteria that can be pathogenic or beneficial. Galaxea fascicularis is one of the dominant massive scleractinian coral species on inshore fringing reefs in the northern South China Sea.Although the abundance of coral-associated bacteria has been investigated in G. fascicularis, less is known about the microorganisms in the gastric cavity. In this study, we specially isolated cultivable bacterial strains from the gastric cavity of G.fascicularis collected from Hainan Island using a noninvasive sampling approach. Among the 101 representative bacterial strains, one Vibrio coralliilyticus strain, SCSIO 43001, was found to be a temperature-dependent opportunistic pathogen of G.fascicularis. The antagonistic activity between the 100 strains and V. coralliilyticus SCSIO 43001 was tested using a modified Burkholder diffusion assay. Our results showed that V. coralliilyticus SCSIO 43001 inhibits the growth of Erythrobacter flavus and Sphingomonas yabuuchiae. Additionally, we found that three Pseudoalteromonas strains showed moderate to high antibacterial activity against V. coralliilyticus SCSIO 43001 and several other coral-associated Gram-negative bacterial strains.These results suggest that competition between the coral pathogen and other bacteria also occurs in the gastric cavity of coral, and Pseudoalteromonas strains in the gastric cavity of G. fascicularis may provide a protective role in the defense against coinhabiting coral pathogens at elevated temperature.
基金supported by the National Key R&D Program of China(Grant Nos.2017YFC0506303&2018YFC1406500)the National Natural Science Foundation of China(Grant Nos.91951203,41706172,31625001&41376174)+2 种基金the Hainan Provincial Key R&D Program(Grant No.ZDYF2018108)supported by the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(Grant No.GML2019ZD0407)the Guangdong Local Innovation Team Program(Grant No.2019BT02Y262)。
文摘Nitrogen cycle is critical to maintain a healthy coral reef ecosystem.Urea can provide a source of nitrogen for coral holobiont and is important for coral calcification through degradation by urease.Despite the involvement of coral-associated bacteria in nitrogen fixation,nitrification and denitrification are well recognized,to what extend urea degradation by bacteria contributing to the urea utilization by coral holobiont remains to be investigated.In this study,we demonstrate that the urea utilization is a common feature of Halomonas spp.that is a dominant genus in cultivable coral-associated bacteria.A urease operon was characterized by genome sequencing and gene knock-out technique in Halomonas meridiana SCSIO 43005,isolated from the gastric cavity of healthy scleractinian coral Galaxea fascicularis.H.meridiana showed high urease activity which was induced by urea and deletion of the urease operon reduced the capability to use urea as solo nitrogen source.Furthermore,approximately 1/3 coral-associated bacteria in the IMG/M database possess complete urease operons indicating the involvement of bacteria-derived ureases in coral holobiont.These results suggest that urease from coral-associated bacteria might be important player in the nitrogen cycling of coral reefs.
