A group of radiolarian fossils with a complete morphological gradient of increasing polarization are reported from upper Devonian successions in southwestern Tianshan, China. Specifically, the important transitional m...A group of radiolarian fossils with a complete morphological gradient of increasing polarization are reported from upper Devonian successions in southwestern Tianshan, China. Specifically, the important transitional mophotypes, Pylentonema transitorum sp. nov., Archocyrtium medium sp. nov. and Quadrapesus transitivus sp. nov, were found. Based on the fact that the new transitional radiolarian fossils resemble more closely to pylentonemids （cyrtoid nassellarians） than to entactinids （spumellarians） in morphology, they are assigned to pylentonemids. Pylentonemids share characters of both the Nassellaria （e.g., horned cephalis, basal opening with pylome） and Spumellaria （e.g., system of trabecular spicules）, and they are thus of evolutionary significance. The evolutionary trend from spumellarians to nassellarians is characterized by （1） internal spicule： from simple trabecular spicules to complicate components （A;Ir,II;D;V;Lr,Li;MB）; （2） polarization of the radiolarian tests due to rearrangment of spine, from radial to an axial symmetry; （3） the gradual formation of a basal opening （aperture, pylome, or podome）; and the transition from a pseudopylome, a primative pylome with a narrow margin on the outer shell, to a true pylome rimmed with a narrow, elevated impermite wall.展开更多
[Objective] This study aimed to explore the origin and evolution of poly- poids in Parakmeria Hu et Cheng through LEAFY gene clone and sequence analysis. [Method] In this study, LEAFY gene in Parakmeria species and it...[Objective] This study aimed to explore the origin and evolution of poly- poids in Parakmeria Hu et Cheng through LEAFY gene clone and sequence analysis. [Method] In this study, LEAFY gene in Parakmeria species and its relative genera was cloned and sequenced using molecular biology methods. With reference to LEAFY gene sequence published by NCBI, the origin pattern of polypoids in Parakmeria was explored and reasons for the distribution layout of different polypoids were analyzed through sequence alignment and phylogenetic analysis. [Result] Different Magnoliaceae species can be distinguished using the LEAFY gene, and there was a length polymorphism found in the 3＋ end of the LEAFY gene, which can be used to divide Magnoliaceae plants of different species or in different genera, thus of high application value. [Conclusion] Most Parakmeria tetraploids are produced by polyploidization of homologous chromosomes, while Parakmeria hexaploids are chiefly produced by both polyploidization of homologous chromosomes and heterologous hybridization.展开更多
The coat protein （CP） genes were cloned and sequenced from viral particles of 11 isolates of citrus tristeza virus （CTV） collected from wild citrus plants in China and 4 Chinese isolates from cultivated sweet oran...The coat protein （CP） genes were cloned and sequenced from viral particles of 11 isolates of citrus tristeza virus （CTV） collected from wild citrus plants in China and 4 Chinese isolates from cultivated sweet orange and pummelo varieties, respectively. By analyzing and comparing the nucleotide and amino acid sequences of CP genes, the 11 wild CTV isolates were found over 92% identical with 4 Chinese CTV isolates and 21 exotic CTV isolates from cultivated citrus. From 91 to 100% of the CTV CP gene sequences in wild type citrus plants were generally well conserved. Genetic evolution analysis indicated that the GC% of the CP gene was less than AT%, and more transition were found in the CP genes than transversion with the transition/transversion ratio ranging from 6.3 to 7.0 among species. The substitution frequency was the highest at the third codon, followed by the first and second codon. The ratio of non-synonymous mutations （du） to synonymous mutations （ds） was far lower than 1, suggesting that the CP gene might have experienced purifying selection in the evolution. Phylogenetic analysis revealed that the 11 CTV isolates in Chinese wild type citrus belonged to different phylogenetic clusters, and shared higher homology and closer relationships with other cultivated citrus CTV isolates from different countries, which indicated complicated genetic relationships among the CTV isolates. In addition, CTV isolates with similar biological characteristics usually located into the same clusters. Therefore, the conclusion was drawn that pathogenicity was critical to evolution and origin of CTV.展开更多
[Objectives]This study was conducted to clarify the species,occurrence and distribution characteristics of sugarcane rust pathogens in low-latitude plateau sugarcane rust areas of Yunnan Province and the phylogenetic ...[Objectives]This study was conducted to clarify the species,occurrence and distribution characteristics of sugarcane rust pathogens in low-latitude plateau sugarcane rust areas of Yunnan Province and the phylogenetic relationship between the pathogens and that between them and other rust fungi of the genus Puccinia.[Methods]Fifty seven sugarcane rust samples collected from the sugarcane areas of Baoshan,Lincang,Menghai,Menglian,Ximeng,Lancang and Wenshan in Yunnan were subjected to molecular identification.[Results]The four sugarcane rust samples from Haiyin1 hao in Menghai,Yunnan Province belonged to orange rust of sugarcane,and the pathogen was Puccinia kuehnii Butler.;and other 53 samples of sugarcane rust belonged to brown rust of sugarcane,and the pathogen was Puccinia melanocephala Syd.et P.Syd.The rDNA sequences of other rust fungi from the genus Puccinia were downloaded from GenBank and used for the construction of an NJ tree for systematic evolution analysis together with the sequences obtained in this study.The results showed that the four P.kuehnii sequences obtained in this study were clustered with Puccinia polysora(GenBank accession number:GU058024)into one group,and they were close genetically;the 53 P.melanocephala sequences were clustered with P.nakanishikii(GenBank accession number:GU058002),P.rufipes(GenBank accession number:AJ296545),Aecidium deutziae(GenBank accession number:KU309317)and P.coronata(GenBank accession number:DQ354526)into one group,and they had a close genetic relationship;and the genetic relationship of the two species of sugarcane rust fungi identified in this study was relatively distant.[Conclusions]This study provides a scientific basis for sugarcane rust epidemic prediction,disease resistance breeding,and precise prevention and control.展开更多
Sleep has been studied widely in mammals and to some extent in other vertebrates. Higher vertebrates such as birds and mammals have evolved an inimitable rapid eye movement （REM） sleep state. During REM sleep, postu...Sleep has been studied widely in mammals and to some extent in other vertebrates. Higher vertebrates such as birds and mammals have evolved an inimitable rapid eye movement （REM） sleep state. During REM sleep, postural muscles become atonic and the temperature regulating machinery remains suspended. Although REM sleep is present in almost all the terrestrial mammals, the aquatic mammals have either radically reduced or completely eliminated REM sleep. Further, we found a significant negative correlation between REM sleep and the adaptation of the organism to live on land or in water. The amount of REM sleep is highest in terrestrial mammals, significantly reduced in semi-aquatic mammals and completely absent or negligible in aquatic mammals. The aquatic mammals are obligate swimmers and have to sur- face at regular intervals for air. Also, these animals live in thermally challenging environments, where the conductive heat loss is approximately -90 times greater than air. Therefore, they have to be moving most of the time. As an adaptation, they have evolved unihemispheric sleep, during which they can rove as well as rest. A condition that immobilizes muscle activity and suspends the thermoregulatory machinery, as happens during REM sleep, is not suitable for these animals. It is possible that, in accord with Darwin＇s theory, aquatic mammals might have abolished REM sleep with time. In this review, we discuss the possibility of the intrinsic role of aquatic conditions in the elimination of REM sleep in the aquatic mammals.展开更多
The taxonomical position of species of the genus Tamarix(Tamaricaceae) has been criticized because of their gross morphological similarities(such as slender, smooth and reddish-brown branches,grey-green foliage and sc...The taxonomical position of species of the genus Tamarix(Tamaricaceae) has been criticized because of their gross morphological similarities(such as slender, smooth and reddish-brown branches,grey-green foliage and scale leaves), and their systematic relationships remain unclear. In this paper, the leaf epidermal features of 17 species from China are studied based on the micro-morphological characters of the epidermal cells, stomata, salt glands, papillae and epidermal hairs. According to the studies, the leaf epidermal features, together with the character of the flower, are taxonomically clearly distinct. The establishment of Tamarix albiflonum is consolidated. Tamarix korolkowi and Tamarix ramosissima have minimal differences in epidermal characters, and the former is suggested to be a junior synonym. Tamarix ramosissima, Tamarix tarimensis, Tamarix arceuthoides and Tamarix hohenackeri are most similar with respect to their leaf epidermis; considering the common morphological features, habit, distribution and especially the hybridization, it is suggested that these four species are closely genetically related and that the variations among them are probably intraspecific. The new taxonomical evidence indicates the occurrence of13 species and four variants in China. Presently, Tamarix is a typical plant of arid and semi-arid regions, but its Eocene ancestors lived in warm and humid climates in the coastal areas of the ancient Mediterranean Sea.Thus, the papillae or epidermal hairs, which are outgrowths of the outer epidermal cells facilitating the leaf to respond to water stress and commonly seen in the plants growing in arid or semi-arid areas rather than the plants in warm and humid climates, are of relatively recent origin in Tamarix. The primitive species lack papillae or epidermal hairs, while in evolved species these structures are abundant. Based on the ecological adaptations of the epidermal features, the palaeogeographic implications of Tamarix in the Late Cenozoic of Northwest China are also discussed.展开更多
基金This work was supported by the National Nature Science Foundation of China(No.40232019).
文摘A group of radiolarian fossils with a complete morphological gradient of increasing polarization are reported from upper Devonian successions in southwestern Tianshan, China. Specifically, the important transitional mophotypes, Pylentonema transitorum sp. nov., Archocyrtium medium sp. nov. and Quadrapesus transitivus sp. nov, were found. Based on the fact that the new transitional radiolarian fossils resemble more closely to pylentonemids （cyrtoid nassellarians） than to entactinids （spumellarians） in morphology, they are assigned to pylentonemids. Pylentonemids share characters of both the Nassellaria （e.g., horned cephalis, basal opening with pylome） and Spumellaria （e.g., system of trabecular spicules）, and they are thus of evolutionary significance. The evolutionary trend from spumellarians to nassellarians is characterized by （1） internal spicule： from simple trabecular spicules to complicate components （A;Ir,II;D;V;Lr,Li;MB）; （2） polarization of the radiolarian tests due to rearrangment of spine, from radial to an axial symmetry; （3） the gradual formation of a basal opening （aperture, pylome, or podome）; and the transition from a pseudopylome, a primative pylome with a narrow margin on the outer shell, to a true pylome rimmed with a narrow, elevated impermite wall.
基金Supported by the National Natural Science Foundation of China(NSFC31160432)the Key Project of Department of Education,Yunnan Province(2011Z108)~~
文摘[Objective] This study aimed to explore the origin and evolution of poly- poids in Parakmeria Hu et Cheng through LEAFY gene clone and sequence analysis. [Method] In this study, LEAFY gene in Parakmeria species and its relative genera was cloned and sequenced using molecular biology methods. With reference to LEAFY gene sequence published by NCBI, the origin pattern of polypoids in Parakmeria was explored and reasons for the distribution layout of different polypoids were analyzed through sequence alignment and phylogenetic analysis. [Result] Different Magnoliaceae species can be distinguished using the LEAFY gene, and there was a length polymorphism found in the 3＋ end of the LEAFY gene, which can be used to divide Magnoliaceae plants of different species or in different genera, thus of high application value. [Conclusion] Most Parakmeria tetraploids are produced by polyploidization of homologous chromosomes, while Parakmeria hexaploids are chiefly produced by both polyploidization of homologous chromosomes and heterologous hybridization.
基金supported by the National Natural Science Foundation of China (30900977)the Key Project 210111 of Chinese Ministry of Education and Natural Science Foundation Project of CQ CSTC (2009BB1310)
文摘The coat protein （CP） genes were cloned and sequenced from viral particles of 11 isolates of citrus tristeza virus （CTV） collected from wild citrus plants in China and 4 Chinese isolates from cultivated sweet orange and pummelo varieties, respectively. By analyzing and comparing the nucleotide and amino acid sequences of CP genes, the 11 wild CTV isolates were found over 92% identical with 4 Chinese CTV isolates and 21 exotic CTV isolates from cultivated citrus. From 91 to 100% of the CTV CP gene sequences in wild type citrus plants were generally well conserved. Genetic evolution analysis indicated that the GC% of the CP gene was less than AT%, and more transition were found in the CP genes than transversion with the transition/transversion ratio ranging from 6.3 to 7.0 among species. The substitution frequency was the highest at the third codon, followed by the first and second codon. The ratio of non-synonymous mutations （du） to synonymous mutations （ds） was far lower than 1, suggesting that the CP gene might have experienced purifying selection in the evolution. Phylogenetic analysis revealed that the 11 CTV isolates in Chinese wild type citrus belonged to different phylogenetic clusters, and shared higher homology and closer relationships with other cultivated citrus CTV isolates from different countries, which indicated complicated genetic relationships among the CTV isolates. In addition, CTV isolates with similar biological characteristics usually located into the same clusters. Therefore, the conclusion was drawn that pathogenicity was critical to evolution and origin of CTV.
基金Supported by China Agriculture Research System of MOF and MARA(CARS-170303)Joint Special Project of Basic Agricultural Research in Yunnan Province(2018FG001-029)+1 种基金"Yunling Industrial Technology Leading Talents"Training Project(2018LJRC56)Special Fund for the Construction of Modern Agricultural Industry Technology System in Yunnan Province(YNGZTX-4-92)。
文摘[Objectives]This study was conducted to clarify the species,occurrence and distribution characteristics of sugarcane rust pathogens in low-latitude plateau sugarcane rust areas of Yunnan Province and the phylogenetic relationship between the pathogens and that between them and other rust fungi of the genus Puccinia.[Methods]Fifty seven sugarcane rust samples collected from the sugarcane areas of Baoshan,Lincang,Menghai,Menglian,Ximeng,Lancang and Wenshan in Yunnan were subjected to molecular identification.[Results]The four sugarcane rust samples from Haiyin1 hao in Menghai,Yunnan Province belonged to orange rust of sugarcane,and the pathogen was Puccinia kuehnii Butler.;and other 53 samples of sugarcane rust belonged to brown rust of sugarcane,and the pathogen was Puccinia melanocephala Syd.et P.Syd.The rDNA sequences of other rust fungi from the genus Puccinia were downloaded from GenBank and used for the construction of an NJ tree for systematic evolution analysis together with the sequences obtained in this study.The results showed that the four P.kuehnii sequences obtained in this study were clustered with Puccinia polysora(GenBank accession number:GU058024)into one group,and they were close genetically;the 53 P.melanocephala sequences were clustered with P.nakanishikii(GenBank accession number:GU058002),P.rufipes(GenBank accession number:AJ296545),Aecidium deutziae(GenBank accession number:KU309317)and P.coronata(GenBank accession number:DQ354526)into one group,and they had a close genetic relationship;and the genetic relationship of the two species of sugarcane rust fungi identified in this study was relatively distant.[Conclusions]This study provides a scientific basis for sugarcane rust epidemic prediction,disease resistance breeding,and precise prevention and control.
基金supported by grants from DBT,DST,UGC-CAS,New Delhi,India
文摘Sleep has been studied widely in mammals and to some extent in other vertebrates. Higher vertebrates such as birds and mammals have evolved an inimitable rapid eye movement （REM） sleep state. During REM sleep, postural muscles become atonic and the temperature regulating machinery remains suspended. Although REM sleep is present in almost all the terrestrial mammals, the aquatic mammals have either radically reduced or completely eliminated REM sleep. Further, we found a significant negative correlation between REM sleep and the adaptation of the organism to live on land or in water. The amount of REM sleep is highest in terrestrial mammals, significantly reduced in semi-aquatic mammals and completely absent or negligible in aquatic mammals. The aquatic mammals are obligate swimmers and have to sur- face at regular intervals for air. Also, these animals live in thermally challenging environments, where the conductive heat loss is approximately -90 times greater than air. Therefore, they have to be moving most of the time. As an adaptation, they have evolved unihemispheric sleep, during which they can rove as well as rest. A condition that immobilizes muscle activity and suspends the thermoregulatory machinery, as happens during REM sleep, is not suitable for these animals. It is possible that, in accord with Darwin＇s theory, aquatic mammals might have abolished REM sleep with time. In this review, we discuss the possibility of the intrinsic role of aquatic conditions in the elimination of REM sleep in the aquatic mammals.
基金supported by the National Natural Science Foundation of China, Grant 41271070the West Light Foundation of the Chinese Academy of Sciences, Grant 2015-XBQN-B-25
文摘The taxonomical position of species of the genus Tamarix(Tamaricaceae) has been criticized because of their gross morphological similarities(such as slender, smooth and reddish-brown branches,grey-green foliage and scale leaves), and their systematic relationships remain unclear. In this paper, the leaf epidermal features of 17 species from China are studied based on the micro-morphological characters of the epidermal cells, stomata, salt glands, papillae and epidermal hairs. According to the studies, the leaf epidermal features, together with the character of the flower, are taxonomically clearly distinct. The establishment of Tamarix albiflonum is consolidated. Tamarix korolkowi and Tamarix ramosissima have minimal differences in epidermal characters, and the former is suggested to be a junior synonym. Tamarix ramosissima, Tamarix tarimensis, Tamarix arceuthoides and Tamarix hohenackeri are most similar with respect to their leaf epidermis; considering the common morphological features, habit, distribution and especially the hybridization, it is suggested that these four species are closely genetically related and that the variations among them are probably intraspecific. The new taxonomical evidence indicates the occurrence of13 species and four variants in China. Presently, Tamarix is a typical plant of arid and semi-arid regions, but its Eocene ancestors lived in warm and humid climates in the coastal areas of the ancient Mediterranean Sea.Thus, the papillae or epidermal hairs, which are outgrowths of the outer epidermal cells facilitating the leaf to respond to water stress and commonly seen in the plants growing in arid or semi-arid areas rather than the plants in warm and humid climates, are of relatively recent origin in Tamarix. The primitive species lack papillae or epidermal hairs, while in evolved species these structures are abundant. Based on the ecological adaptations of the epidermal features, the palaeogeographic implications of Tamarix in the Late Cenozoic of Northwest China are also discussed.
