Dental implants have restored masticatory function to over 100000000 individuals,yet almost 1000000 implants fail each year due to peri-implantitis,a disease triggered by peri-implant microbial dysbiosis.Our ability t...Dental implants have restored masticatory function to over 100000000 individuals,yet almost 1000000 implants fail each year due to peri-implantitis,a disease triggered by peri-implant microbial dysbiosis.Our ability to prevent and treat peri-implantitis is hampered by a paucity of knowledge of how these biomes are acquired and the factors that engender normobiosis.Therefore,we combined a 3-month interventional study of 15 systemically and periodontally healthy adults with whole genome sequencing,finescale enumeration and graph theoretics to interrogate colonization dynamics in the pristine peri-implant sulcus.We discovered that colonization trajectories of implants differ substantially from adjoining teeth in acquisition of new members and development of functional synergies.Source-tracking algorithms revealed that this niche is initially seeded by bacteria trapped within the coverscrew chamber during implant placement.These pioneer species stably colonize the microbiome and exert a sustained influence on the ecosystem by serving as anchors of influential hubs and by providing functions that enable cell replication and biofilm maturation.Unlike the periodontal microbiome,recruitment of new members to the peri-implant community occurs on nepotistic principles.Maturation is accompanied by a progressive increase in anaerobiosis,however,the predominant functionalities are oxygen-dependent over the 12-weeks.The peri-implant community is easily perturbed following crown placement,but demonstrates remarkable resilience;returning to pre-perturbation states within three weeks.This study highlights important differences in the development of the periodontal and peri-implant ecosystems,and signposts the importance of placing implants in periodontally healthy individuals or following the successful resolution of periodontal disease.展开更多
Saline-alkali soil severely reduces the productivity of crops,including maize(Zea mays).Although several genes associated with saline-alkali tolerance have been identified in maize,the underlying regulatory mechanism ...Saline-alkali soil severely reduces the productivity of crops,including maize(Zea mays).Although several genes associated with saline-alkali tolerance have been identified in maize,the underlying regulatory mechanism remains elusive.Here,we report a direct link between colonization by arbuscular mycorrhizal fungi(AMF)and saline-alkali tolerance in maize.We identify s75,a natural maize mutant that cannot survive under moderate saline-alkali soil conditions or establish AM symbioses.The saline-alkali hypersensitive phenotype of s75 is caused by a 1340-bp deletion in Zm00001d033915,designated as ZmL75.This gene encodes a glycerol-3-phosphate acyltransferase localized in the endoplasmic reticulum,and is responsible for AMF colonization.ZmL75 expression levels in roots correspond with the root length colonization(RLC)rate during early vegetative development.Notably,the s75 mutant line shows a complete loss of AMF colonization,along with alterations in the diversity and structure of its root fungal microbiota.Conversely,overexpression of ZmL75 increases the RLC rate and enhances tolerance to saline-alkali soil conditions.These results suggest that ZmL75 is required for symbiosis with AMF,which directly improves saline-alkali tolerance.Our findings provide insights into maize-AMF interactions and offer a potential strategy for maize improvement.展开更多
In the early years of the 20th century,Britain sought to compete with Russia for dominance in East Asia,and set its sights on the strategic location of Xizang.Smallpox virus epidemics have been documented in Xizang si...In the early years of the 20th century,Britain sought to compete with Russia for dominance in East Asia,and set its sights on the strategic location of Xizang.Smallpox virus epidemics have been documented in Xizang since the 7th century,and smallpox remained a major public health issue in Xizang until the early 20th century.The British colonizers learned from their experience of passing on biological science and technology in India and carried out a series of medical activities in Xizang,the most influential of which was the smallpox vaccination for the people of Gyantse and other places.This paper examines the history of the fight against smallpox in Xizang from 1900 to 1907,and studies the historical process of British colonial expansion in Xizang,as well as the interaction between the Qing government and the British invaders in medical and healthcare events such as vaccination in Xizang.展开更多
Plasmid pVK1001 which carried the gfp gene of GFPmut2, a mutant of GFP, was introduced into Azospirillum brasilense Yu62 by electroporation. Maize seedlings were inoculated with the GFP-labelled baeteria and grown gno...Plasmid pVK1001 which carried the gfp gene of GFPmut2, a mutant of GFP, was introduced into Azospirillum brasilense Yu62 by electroporation. Maize seedlings were inoculated with the GFP-labelled baeteria and grown gnotobiotically in flask with semi-solid agar medium. Observations were performed with confocal laser scanning microscopy (CLSM) and electron microscopy, respectively, at 8 d and 12 d after inoculation. Confocal laser scanning microscopy showed that A. brasilense Yu62 could penetrate into the cortex tissue, colonizing in the intercellular spaces of the parenchyma cells of the cortex tissue. Transmission and scanning electron microscopy (TEM) showed that the majority of the bacteria colonized on the root surface and only a minority of them resided in the root interior.展开更多
基金supported by National Institutes of Health R03DE027492 to Shareef Dabdoubsupported by National Institutes of Health,project number 7R01DE027857-06supported by National Institutes of Health R56DE033913 awarded to Purnima Kumar.
文摘Dental implants have restored masticatory function to over 100000000 individuals,yet almost 1000000 implants fail each year due to peri-implantitis,a disease triggered by peri-implant microbial dysbiosis.Our ability to prevent and treat peri-implantitis is hampered by a paucity of knowledge of how these biomes are acquired and the factors that engender normobiosis.Therefore,we combined a 3-month interventional study of 15 systemically and periodontally healthy adults with whole genome sequencing,finescale enumeration and graph theoretics to interrogate colonization dynamics in the pristine peri-implant sulcus.We discovered that colonization trajectories of implants differ substantially from adjoining teeth in acquisition of new members and development of functional synergies.Source-tracking algorithms revealed that this niche is initially seeded by bacteria trapped within the coverscrew chamber during implant placement.These pioneer species stably colonize the microbiome and exert a sustained influence on the ecosystem by serving as anchors of influential hubs and by providing functions that enable cell replication and biofilm maturation.Unlike the periodontal microbiome,recruitment of new members to the peri-implant community occurs on nepotistic principles.Maturation is accompanied by a progressive increase in anaerobiosis,however,the predominant functionalities are oxygen-dependent over the 12-weeks.The peri-implant community is easily perturbed following crown placement,but demonstrates remarkable resilience;returning to pre-perturbation states within three weeks.This study highlights important differences in the development of the periodontal and peri-implant ecosystems,and signposts the importance of placing implants in periodontally healthy individuals or following the successful resolution of periodontal disease.
基金National Natural Science Foundation of China(No.32171947 and No.31671699)which supported this research.
文摘Saline-alkali soil severely reduces the productivity of crops,including maize(Zea mays).Although several genes associated with saline-alkali tolerance have been identified in maize,the underlying regulatory mechanism remains elusive.Here,we report a direct link between colonization by arbuscular mycorrhizal fungi(AMF)and saline-alkali tolerance in maize.We identify s75,a natural maize mutant that cannot survive under moderate saline-alkali soil conditions or establish AM symbioses.The saline-alkali hypersensitive phenotype of s75 is caused by a 1340-bp deletion in Zm00001d033915,designated as ZmL75.This gene encodes a glycerol-3-phosphate acyltransferase localized in the endoplasmic reticulum,and is responsible for AMF colonization.ZmL75 expression levels in roots correspond with the root length colonization(RLC)rate during early vegetative development.Notably,the s75 mutant line shows a complete loss of AMF colonization,along with alterations in the diversity and structure of its root fungal microbiota.Conversely,overexpression of ZmL75 increases the RLC rate and enhances tolerance to saline-alkali soil conditions.These results suggest that ZmL75 is required for symbiosis with AMF,which directly improves saline-alkali tolerance.Our findings provide insights into maize-AMF interactions and offer a potential strategy for maize improvement.
文摘In the early years of the 20th century,Britain sought to compete with Russia for dominance in East Asia,and set its sights on the strategic location of Xizang.Smallpox virus epidemics have been documented in Xizang since the 7th century,and smallpox remained a major public health issue in Xizang until the early 20th century.The British colonizers learned from their experience of passing on biological science and technology in India and carried out a series of medical activities in Xizang,the most influential of which was the smallpox vaccination for the people of Gyantse and other places.This paper examines the history of the fight against smallpox in Xizang from 1900 to 1907,and studies the historical process of British colonial expansion in Xizang,as well as the interaction between the Qing government and the British invaders in medical and healthcare events such as vaccination in Xizang.
文摘Plasmid pVK1001 which carried the gfp gene of GFPmut2, a mutant of GFP, was introduced into Azospirillum brasilense Yu62 by electroporation. Maize seedlings were inoculated with the GFP-labelled baeteria and grown gnotobiotically in flask with semi-solid agar medium. Observations were performed with confocal laser scanning microscopy (CLSM) and electron microscopy, respectively, at 8 d and 12 d after inoculation. Confocal laser scanning microscopy showed that A. brasilense Yu62 could penetrate into the cortex tissue, colonizing in the intercellular spaces of the parenchyma cells of the cortex tissue. Transmission and scanning electron microscopy (TEM) showed that the majority of the bacteria colonized on the root surface and only a minority of them resided in the root interior.
