Mesoproterozoic Shennongjia Group in Shennongjia Area can be divided into three subgroups in ascender order. Of which the lower subgroup includes Yingwodong, Dayanping, Macaoyuan, Luanshigou, Dawokeng and Kuangshishan...Mesoproterozoic Shennongjia Group in Shennongjia Area can be divided into three subgroups in ascender order. Of which the lower subgroup includes Yingwodong, Dayanping, Macaoyuan, Luanshigou, Dawokeng and Kuangshishan formations;the middle subgroup is formed by Yemahe, Wenshuihe and Shicaohe formations;the upper subgroup consists of Songziyuan and Wagangxi formations. Stromatolites developed very well in the carbonate rocks of each subgroup in Shennongjia Group. Based on descriptions of stromatolites macrotypes and their characteristics, this paper studied the formation environments, discussed the relationship among types, sizes, abundance of stromatolites and sedimentary environment, and established the formation and development pattern of stromatolites. As a result, this research also reveals the paleoenvironment and paleoclimate during the period of the Shennongjia Group deposited, which is beneficial to the study of paleoenvironment, paleogeography and paleoclimate, stratigraphic succession and regional correlation of the northern edge of Yangtze block. Stromatolites of Shennongjia Group are mainly conical, columnar, domal, wavy, stratiform and stromatolite reefs. The columnar and conical stromatolites are well developed. Conical stromatolites are mainly monomers, with a variety of pyramidal types, ranging in diameter from a few millimeters to several meters and formed in the high energy subtidal zone and tidal lagoon environment. Most of the columnar stromatolites are medium to small sizes implied a wide and gentle slope environment at that time. Stratiform (including wavy) stromatolites are larger scales and extends far away and distributed most widely in almost every horizon in the carbonate rocks. Stratiform stromatolites can be formed in low energy environments such as subtidal and intertidal zones and supratidal belts. Wavy stromatolites often developed in the hydrodynamic energy condition from weak energy intertidal zone gradually strengthened to the below of the high energy supratidal. Although stromatolite reefs can be a single or multiform combination, they developed mainly consisted of laminar or small walled columnar and large domal stromatolites. Shicaohe Formation also partially developed large domical stromatolites, the depositional environment is from the upper intertidal to supratidal zone. Stromatolite in Shennongjia Group usually appears as a combination of “Stratiform (wavy)-dome-columnar-coniform ” or “stratiform-dome-coniform-columnar-dome-stratiform ” vertieally, which represents the seawater depth from shallower to deeper or from shallow to deep and then to shallow again. These phenomenons generally reflected a stable sea level and companied with a high frequency oscillation. Comprehensive researches on the stratigraphy, sedimentary facies, sedimentary environment and the stromatolite types and their characteristics in the Shennongjia Group indicated that the Shennongjia Area is located on a gentle slope of carbonate platform in the passive continental edge, generally, i.e., one of warm and humid climate shallow water zone or/and a cold-drought climate, and had been experienced with eustatic cycles during the Shennongjia Group deposited.展开更多
CRISPR-Cas systems provide bacteria and archaea with adaptive immunity against mobile genetic elements(MGEs)through uptake of invader-derived spacers.De novo adaptation samples spacers from both invaders and hosts,whe...CRISPR-Cas systems provide bacteria and archaea with adaptive immunity against mobile genetic elements(MGEs)through uptake of invader-derived spacers.De novo adaptation samples spacers from both invaders and hosts,whereas primed adaptation shows higher specificity to sample spacers from invaders in many model systems as well as in the subtype I-F system of Zymomonas mobilis.Self-derived spacers will lead to CRISPR self-interference.However,our in vivo study demonstrated that this species used the microhomology-mediated end joining(MMEJ)pathway to efficiently repair subtype I-F CRISPR-Cas system-mediated DNA breaks guided by the self-targeting spacers.MMEJ repair of DNA breaks requires direct microhomologous sequences flanking the protospacers and leads to DNA deletions covering the protospacers.Importantly,CRISPR-mediated genomic DNA breaks failed to be repaired via MMEJ pathway in presence of higher copies of short homologous DNA.Moreover,CRISPR-cleaved exogenous plasmid DNA was failed to be repaired through MMEJ pathway,probably due to the inhibition of MMEJ by the presence of higher copies of the plasmid DNA in Z.mobilis.Our results infer that MMEJ pathway discriminates DNA damages between in the host chromosome versus mobile genetic element(MGE)DNA,and maintains genome stability post CRISPR immunity in Z.mobilis.展开更多
The Late Jurassic-Early Cretaceous Santai Formation, sporadically distributed in western Shandong Province, comprises terrestrial alluvial-eolian successions, which records regional wind patterns and paleogeography in...The Late Jurassic-Early Cretaceous Santai Formation, sporadically distributed in western Shandong Province, comprises terrestrial alluvial-eolian successions, which records regional wind patterns and paleogeography in eastern North China. This paper conducts an analysis of eolian stratification, bounding surfaces, facies architecture and paleowind direction of the Santai Formation in the east of the Mengyin Basin, western Shandong Province. Three basic types of eolian stratification are recognized in the Santai Formation, including grainflow strata, wind ripple strata and adhesion strata, and have been grouped into eolian dune and interdune facies associations. The occurrences of reactivation surfaces and superimposition surfaces within eolian dune deposits indicate active compound dunes or draas. The association of adhesion strata with grainflow or windripple strata is the development of a wet eolian system. Cross-strata dip direction indicates different paleowind directions from the lower to the upper part of the Santai paleoerg. The lower part of the paleoerg was characterized by paleowinds blowing from northwest to northeast, whereas the upper part was under the influence of paleowinds consistently towards east to northeast. The identified changes in wind directions possibly suggest wind regime shifts from monsoon circulation to westlies of planetary wind system, which may be related with the collapse of the East China Plateau during the Late Jurassic to Early Cretaceous.展开更多
The terrestrial upper Jurassic-Cretaceous (upper and lower)-Cenozoic stratigraphic succession developed continuously in Shandong province. There are intact and continuous terrestrial paleoecosystems dominated by dinos...The terrestrial upper Jurassic-Cretaceous (upper and lower)-Cenozoic stratigraphic succession developed continuously in Shandong province. There are intact and continuous terrestrial paleoecosystems dominated by dinosaurs, including five vertebrate fauna (bone fossil assemblages) beds from the bottom to top in the Cretaceous successions of Shandong Province. There are multiple vertebrate footprints (group) bearing beds in the transition period between Jurassic-Cretaceous and Early Cretaceous, and multiple large-scale dinosaur burial bone beds in Late Cretaceous. In recent years, it has also been found that extraterrestrial impact geological event may occur in the K/Pg transition over a hundred meters (siliceous pellet and gamma element anomalies, etc.). Shandong has a well-developed terrestrial Cretaceous succession with perfect information on paleoenvironment and paleoecology, which is an ideal area to explore the co-evolutionary relationship between terrestrial biota and paleoenvironment.展开更多
基金This research was co-supported by the National Key Research and Development Program of China (2016YFC0601001),the National Natural Science Foundation of China (41472082)China Geological Survey Projects (DD20160120-01)+1 种基金Globe Geopark of Shennongjia. We are grateful to the leaders of Shennongjia National Park and Mr. Zhixian Wang,Quan Zhong gave great assistances and warmly aidsthe field survey was under careful direction by Mr. Lesheng Qu from Hubei Geological Survey,Mr. Yuansheng Geng from Institute of Geology,CAGS. Sincere thanks are also given Mr. Zejiu Wang,Xin Shang and Mrs. Xiulan Ma from Chinese Academy of Geological Sciences (CAGS) and All China Commission of Stratigraphy.
文摘Mesoproterozoic Shennongjia Group in Shennongjia Area can be divided into three subgroups in ascender order. Of which the lower subgroup includes Yingwodong, Dayanping, Macaoyuan, Luanshigou, Dawokeng and Kuangshishan formations;the middle subgroup is formed by Yemahe, Wenshuihe and Shicaohe formations;the upper subgroup consists of Songziyuan and Wagangxi formations. Stromatolites developed very well in the carbonate rocks of each subgroup in Shennongjia Group. Based on descriptions of stromatolites macrotypes and their characteristics, this paper studied the formation environments, discussed the relationship among types, sizes, abundance of stromatolites and sedimentary environment, and established the formation and development pattern of stromatolites. As a result, this research also reveals the paleoenvironment and paleoclimate during the period of the Shennongjia Group deposited, which is beneficial to the study of paleoenvironment, paleogeography and paleoclimate, stratigraphic succession and regional correlation of the northern edge of Yangtze block. Stromatolites of Shennongjia Group are mainly conical, columnar, domal, wavy, stratiform and stromatolite reefs. The columnar and conical stromatolites are well developed. Conical stromatolites are mainly monomers, with a variety of pyramidal types, ranging in diameter from a few millimeters to several meters and formed in the high energy subtidal zone and tidal lagoon environment. Most of the columnar stromatolites are medium to small sizes implied a wide and gentle slope environment at that time. Stratiform (including wavy) stromatolites are larger scales and extends far away and distributed most widely in almost every horizon in the carbonate rocks. Stratiform stromatolites can be formed in low energy environments such as subtidal and intertidal zones and supratidal belts. Wavy stromatolites often developed in the hydrodynamic energy condition from weak energy intertidal zone gradually strengthened to the below of the high energy supratidal. Although stromatolite reefs can be a single or multiform combination, they developed mainly consisted of laminar or small walled columnar and large domal stromatolites. Shicaohe Formation also partially developed large domical stromatolites, the depositional environment is from the upper intertidal to supratidal zone. Stromatolite in Shennongjia Group usually appears as a combination of “Stratiform (wavy)-dome-columnar-coniform ” or “stratiform-dome-coniform-columnar-dome-stratiform ” vertieally, which represents the seawater depth from shallower to deeper or from shallow to deep and then to shallow again. These phenomenons generally reflected a stable sea level and companied with a high frequency oscillation. Comprehensive researches on the stratigraphy, sedimentary facies, sedimentary environment and the stromatolite types and their characteristics in the Shennongjia Group indicated that the Shennongjia Area is located on a gentle slope of carbonate platform in the passive continental edge, generally, i.e., one of warm and humid climate shallow water zone or/and a cold-drought climate, and had been experienced with eustatic cycles during the Shennongjia Group deposited.
基金supported by the National Natural Science Foundation of China(31671291 to N.P.,31570055 to M.H.,and 31900400 to T.L.)the Fundamental Research Funds for the Central Universities(2662019PY028 to N.P.)National Natural Science Foundation of China(31900400)。
文摘CRISPR-Cas systems provide bacteria and archaea with adaptive immunity against mobile genetic elements(MGEs)through uptake of invader-derived spacers.De novo adaptation samples spacers from both invaders and hosts,whereas primed adaptation shows higher specificity to sample spacers from invaders in many model systems as well as in the subtype I-F system of Zymomonas mobilis.Self-derived spacers will lead to CRISPR self-interference.However,our in vivo study demonstrated that this species used the microhomology-mediated end joining(MMEJ)pathway to efficiently repair subtype I-F CRISPR-Cas system-mediated DNA breaks guided by the self-targeting spacers.MMEJ repair of DNA breaks requires direct microhomologous sequences flanking the protospacers and leads to DNA deletions covering the protospacers.Importantly,CRISPR-mediated genomic DNA breaks failed to be repaired via MMEJ pathway in presence of higher copies of short homologous DNA.Moreover,CRISPR-cleaved exogenous plasmid DNA was failed to be repaired through MMEJ pathway,probably due to the inhibition of MMEJ by the presence of higher copies of the plasmid DNA in Z.mobilis.Our results infer that MMEJ pathway discriminates DNA damages between in the host chromosome versus mobile genetic element(MGE)DNA,and maintains genome stability post CRISPR immunity in Z.mobilis.
文摘The Late Jurassic-Early Cretaceous Santai Formation, sporadically distributed in western Shandong Province, comprises terrestrial alluvial-eolian successions, which records regional wind patterns and paleogeography in eastern North China. This paper conducts an analysis of eolian stratification, bounding surfaces, facies architecture and paleowind direction of the Santai Formation in the east of the Mengyin Basin, western Shandong Province. Three basic types of eolian stratification are recognized in the Santai Formation, including grainflow strata, wind ripple strata and adhesion strata, and have been grouped into eolian dune and interdune facies associations. The occurrences of reactivation surfaces and superimposition surfaces within eolian dune deposits indicate active compound dunes or draas. The association of adhesion strata with grainflow or windripple strata is the development of a wet eolian system. Cross-strata dip direction indicates different paleowind directions from the lower to the upper part of the Santai paleoerg. The lower part of the paleoerg was characterized by paleowinds blowing from northwest to northeast, whereas the upper part was under the influence of paleowinds consistently towards east to northeast. The identified changes in wind directions possibly suggest wind regime shifts from monsoon circulation to westlies of planetary wind system, which may be related with the collapse of the East China Plateau during the Late Jurassic to Early Cretaceous.
文摘The terrestrial upper Jurassic-Cretaceous (upper and lower)-Cenozoic stratigraphic succession developed continuously in Shandong province. There are intact and continuous terrestrial paleoecosystems dominated by dinosaurs, including five vertebrate fauna (bone fossil assemblages) beds from the bottom to top in the Cretaceous successions of Shandong Province. There are multiple vertebrate footprints (group) bearing beds in the transition period between Jurassic-Cretaceous and Early Cretaceous, and multiple large-scale dinosaur burial bone beds in Late Cretaceous. In recent years, it has also been found that extraterrestrial impact geological event may occur in the K/Pg transition over a hundred meters (siliceous pellet and gamma element anomalies, etc.). Shandong has a well-developed terrestrial Cretaceous succession with perfect information on paleoenvironment and paleoecology, which is an ideal area to explore the co-evolutionary relationship between terrestrial biota and paleoenvironment.
