Dibenzothiophene (DBT) degradation mechanisms and the transformation of pathways during the incubation of three types of coastal sediments with C/N ratios ranging from 1 to 9 were investigated. The DBT degradation eff...Dibenzothiophene (DBT) degradation mechanisms and the transformation of pathways during the incubation of three types of coastal sediments with C/N ratios ranging from 1 to 9 were investigated. The DBT degradation efficiencies were clearly improved with increasing C/N ratio in reed wetland sediments, tidal wetlands sediments and estuary wetland sediments. The quantitative response relationships between DBT degradation rates and related functional genes demonstrate that the Kodama pathway-related gene groups were dominant factors at low C/N ratios, while the 4S-related gene groups mainly determined the degradation rate when the C/N ratio was up to 5. Network analysis also shows that the pathway shifts from the Kodama pathway to the 4S pathway occurred through changes in the connections between functional genomes and rates. Furthermore, there were competition and collaboration between the Kodama and 4S pathways. The 4S pathway-related bacteria were more active in estuary wetland sediments compared with reed wetland sediments and tidal wetland sediments. The higher degradation efficiency in estuary wetland sediments may indicate the greater participation of the 4S pathway in the DBT biodegradation reaction. And the effects of ring cleavage of Kodama pathway caused more complete metabolizing of DBT.展开更多
The realization that body parts of animals and plants can be recruited or coopted for novel functions dates back to,or even predates the observations of Darwin.S.J.Gould and E.S.Vrba recognized a mode of evolution of ...The realization that body parts of animals and plants can be recruited or coopted for novel functions dates back to,or even predates the observations of Darwin.S.J.Gould and E.S.Vrba recognized a mode of evolution of characters that differs from adaptation.The umbrella term aptation was supplemented with the concept of exaptation.Unlike adaptations,which are restricted to features built by selection for their current role,exaptations are features that currently enhance fitness,even though their present role was not a result of natural selection.Exaptations can also arise from nonaptations;these are characters which had previously been evolving neutrally.All nonaptations are potential exaptations.The concept of exaptation was expanded to the molecular genetic level which aided greatly in understanding the enormous potential of neutrally evolving repetitive DNA-including transposed elements,formerly considered junk DNA-for the evolution of genes and genomes.The distinction between adaptations and exaptations is outlined in this review and examples are given.Also elaborated on is the fact that such distinctions are sometimes more difficult to determine;this is a widespread phenomenon in biology,where continua abound and clear borders between states and definitions are rare.展开更多
基金The Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No.51721006)National Natural Science Foundation of China (No.51679001) provided support for this study.
文摘Dibenzothiophene (DBT) degradation mechanisms and the transformation of pathways during the incubation of three types of coastal sediments with C/N ratios ranging from 1 to 9 were investigated. The DBT degradation efficiencies were clearly improved with increasing C/N ratio in reed wetland sediments, tidal wetlands sediments and estuary wetland sediments. The quantitative response relationships between DBT degradation rates and related functional genes demonstrate that the Kodama pathway-related gene groups were dominant factors at low C/N ratios, while the 4S-related gene groups mainly determined the degradation rate when the C/N ratio was up to 5. Network analysis also shows that the pathway shifts from the Kodama pathway to the 4S pathway occurred through changes in the connections between functional genomes and rates. Furthermore, there were competition and collaboration between the Kodama and 4S pathways. The 4S pathway-related bacteria were more active in estuary wetland sediments compared with reed wetland sediments and tidal wetland sediments. The higher degradation efficiency in estuary wetland sediments may indicate the greater participation of the 4S pathway in the DBT biodegradation reaction. And the effects of ring cleavage of Kodama pathway caused more complete metabolizing of DBT.
文摘The realization that body parts of animals and plants can be recruited or coopted for novel functions dates back to,or even predates the observations of Darwin.S.J.Gould and E.S.Vrba recognized a mode of evolution of characters that differs from adaptation.The umbrella term aptation was supplemented with the concept of exaptation.Unlike adaptations,which are restricted to features built by selection for their current role,exaptations are features that currently enhance fitness,even though their present role was not a result of natural selection.Exaptations can also arise from nonaptations;these are characters which had previously been evolving neutrally.All nonaptations are potential exaptations.The concept of exaptation was expanded to the molecular genetic level which aided greatly in understanding the enormous potential of neutrally evolving repetitive DNA-including transposed elements,formerly considered junk DNA-for the evolution of genes and genomes.The distinction between adaptations and exaptations is outlined in this review and examples are given.Also elaborated on is the fact that such distinctions are sometimes more difficult to determine;this is a widespread phenomenon in biology,where continua abound and clear borders between states and definitions are rare.