Ephrin ligands interact with Eph receptors to regulate a wide variety of biological and pathological processes. Recent studies have identified several downstream pathways that mediate the functions of these receptors....Ephrin ligands interact with Eph receptors to regulate a wide variety of biological and pathological processes. Recent studies have identified several downstream pathways that mediate the functions of these receptors. Activation of the receptors by ephrin binding results in the phosphorylation of the receptor tyrosine residues. These phospho- rylated residues serve as docking sites for many of the downstream signaling pathways. However, the relative contributions of different phosphotyrosine residues remain undefined. In the present study, we mutated each individual tyrosine residues in the cytoplasmic domain of EphA3 receptor and studied the effects using cell migration, process retraction, and growth cone collapse assays. Stimulation of the EphA3 receptor with ephrin-A5 inhibits 293A cell mi- gration, reduces NG108-15 cell neurite outgrowth, and induces growth cone collapse in hippocampal neurons. Muta- tion of either Y602 or Y779 alone partially decreases EphA3-induced responses. Full abrogation can only be achieved with mutations of both Y602 and Y779. These observations suggest a collaborative model of different downstream pathways.展开更多
This article scrutinizes three texts about Xun Zi written during the Qin-Han period： the final part of ＂The Questions of Yao＂ in the Xunzi, a rebuttal by one of Xun Zi＇s disciples of the idea that Xun Zi was infer...This article scrutinizes three texts about Xun Zi written during the Qin-Han period： the final part of ＂The Questions of Yao＂ in the Xunzi, a rebuttal by one of Xun Zi＇s disciples of the idea that Xun Zi was inferior to Confucius; ＂Mencius and Xun Zi＂ by Sima Qian in his Records of the Grand Historian; and the Annotated Book of the Xunzi by Liu Xiang. We explore the images of Xun Zi as a great Confucian （大儒） that emerge from these texts, as well as their authors＇ motives for writing. These texts are understood within three contexts： first, the self-identification of a Confucian; second, the dispute between Confucianism and Daoism; and lastly, the distinction between the classics and the annals and biographies. Due to their different discourse environments, Xun Zi＇s great Confucian image project a different significance in each： in one, he is a model of action who can act in accordance with perfected morality; in another, he is a model of ＂private words,＂ who can counter the philosophers of his day and become the teacher of kings; and finally, he is a model of ＂official learning,＂ able to use his knowledge of the classics in practical statecraft and elucidate the kingly Way. Overall, these three texts represent three types of discourse on a great Confucian. At thesame time, they also exhibit their writers＇ consciousness of their times and their views of the genealogy of daotong, or transmission of the Way; hence their significance for intellectual history.展开更多
We consider a modified Markov branching process incorporating with both state-independent immigration-migration and resurrection. The effect of state-independent immigration-migration is firstly in- vestigated in deta...We consider a modified Markov branching process incorporating with both state-independent immigration-migration and resurrection. The effect of state-independent immigration-migration is firstly in- vestigated in detail. The explicit expressions for the extinction probabilities and mean extinction times are presented. The ergodicity and stability properties of the process incorporating with resurrection structure are then investigated. The conditions for recurrence, ergodicity and exponential ergodicity are obtained. An explicit expression for the equilibrium distribution is also presented. As a preparation, the criteria for regularity and uniqueness for such structure are firstly established.展开更多
During migration, birds can show different responses to wind in relation to distance to the goal, experience, ecologi- cal barriers and visibility of landmarks. We analysed the effect of wind （tailwinds and crosswind...During migration, birds can show different responses to wind in relation to distance to the goal, experience, ecologi- cal barriers and visibility of landmarks. We analysed the effect of wind （tailwinds and crosswinds） on daily movement rates （for- ward and perpendicular） of Eleonora＇s falcons using ARGOS satellite telemetry, during their trans-continental autumn migration to Madagascar, in relation to the different crossed regions and individuals＇ age class. Our results showed that the effect of wind on daily movement rates was not uniform, being stronger in the farthest region from the migration goal, the Sahara desert, with adults being more affected than juveniles in this region. In the Sahel, the results were more conflicting, perhaps because daily movements were more shaped by the distribution of food resources. In Equatorial Africa, daily movement rates were mainly af- fected by crosswinds. Still, it remains unclear which orientation mechanism allows Eleonora＇s falcons to reach such a narrow wintering area compensating also for wind displacement展开更多
The Hengduan Mountains(henceforth H-D Mountains) on the Tibet Plateau are a distribution and diversity center for many alpine genera. We examine patterns of genetic variation in an arctic-alpine plant to evaluate the ...The Hengduan Mountains(henceforth H-D Mountains) on the Tibet Plateau are a distribution and diversity center for many alpine genera. We examine patterns of genetic variation in an arctic-alpine plant to evaluate the possibility that the H-D Mountains constitute the area of origin of the species as well as to uncover postglacial migration routes. 220 individuals of the arctic-alpine plant Koenigia islandica were sampled from 26 populations distributed in western China and northern Finland. DNA haplotypes were identified using restriction site analysis of two chloroplast DNA intergene spacer regions, atpB-rbcL and trnL-trnF. We examined the geographical distribution of haplotype diversity in relation to latitude, and also compared various indices of diversity in putatively glaciated and unglaciated regions. Patterns of migration were inferred using nested clade analysis. A total of 25 haplotypes were detected. High haplotype diversity was found in the H-D Mountains. H3 and its radiated haplotypes were distributed in the Himalayas. Two haplotypes were fixed concurrently in the H-D Mountains and northern Finland. High genetic diversity of K. islandica and high species diversity of K. islandica are expected in the origin area. Our observations suggest that the H-D Mountains are not only the place of origin of K. islandica, but also the refugia for K. islandica on the Tibet Plateau. What is more, the migration route for the arctic-alpine plant K. islandica must have originated in the region defined by the H-D Mountains in western China extending northward to the Arctic circumpolar, and moved westward along the Himalayas, then northward across the Altay Mountains and the Central Siberian Plateau at different time periods.展开更多
文摘Ephrin ligands interact with Eph receptors to regulate a wide variety of biological and pathological processes. Recent studies have identified several downstream pathways that mediate the functions of these receptors. Activation of the receptors by ephrin binding results in the phosphorylation of the receptor tyrosine residues. These phospho- rylated residues serve as docking sites for many of the downstream signaling pathways. However, the relative contributions of different phosphotyrosine residues remain undefined. In the present study, we mutated each individual tyrosine residues in the cytoplasmic domain of EphA3 receptor and studied the effects using cell migration, process retraction, and growth cone collapse assays. Stimulation of the EphA3 receptor with ephrin-A5 inhibits 293A cell mi- gration, reduces NG108-15 cell neurite outgrowth, and induces growth cone collapse in hippocampal neurons. Muta- tion of either Y602 or Y779 alone partially decreases EphA3-induced responses. Full abrogation can only be achieved with mutations of both Y602 and Y779. These observations suggest a collaborative model of different downstream pathways.
文摘This article scrutinizes three texts about Xun Zi written during the Qin-Han period： the final part of ＂The Questions of Yao＂ in the Xunzi, a rebuttal by one of Xun Zi＇s disciples of the idea that Xun Zi was inferior to Confucius; ＂Mencius and Xun Zi＂ by Sima Qian in his Records of the Grand Historian; and the Annotated Book of the Xunzi by Liu Xiang. We explore the images of Xun Zi as a great Confucian （大儒） that emerge from these texts, as well as their authors＇ motives for writing. These texts are understood within three contexts： first, the self-identification of a Confucian; second, the dispute between Confucianism and Daoism; and lastly, the distinction between the classics and the annals and biographies. Due to their different discourse environments, Xun Zi＇s great Confucian image project a different significance in each： in one, he is a model of action who can act in accordance with perfected morality; in another, he is a model of ＂private words,＂ who can counter the philosophers of his day and become the teacher of kings; and finally, he is a model of ＂official learning,＂ able to use his knowledge of the classics in practical statecraft and elucidate the kingly Way. Overall, these three texts represent three types of discourse on a great Confucian. At thesame time, they also exhibit their writers＇ consciousness of their times and their views of the genealogy of daotong, or transmission of the Way; hence their significance for intellectual history.
基金supported by National Natural Science Foundations of China (Grant Nos. 10771216 and 11071259)
文摘We consider a modified Markov branching process incorporating with both state-independent immigration-migration and resurrection. The effect of state-independent immigration-migration is firstly in- vestigated in detail. The explicit expressions for the extinction probabilities and mean extinction times are presented. The ergodicity and stability properties of the process incorporating with resurrection structure are then investigated. The conditions for recurrence, ergodicity and exponential ergodicity are obtained. An explicit expression for the equilibrium distribution is also presented. As a preparation, the criteria for regularity and uniqueness for such structure are firstly established.
文摘During migration, birds can show different responses to wind in relation to distance to the goal, experience, ecologi- cal barriers and visibility of landmarks. We analysed the effect of wind （tailwinds and crosswinds） on daily movement rates （for- ward and perpendicular） of Eleonora＇s falcons using ARGOS satellite telemetry, during their trans-continental autumn migration to Madagascar, in relation to the different crossed regions and individuals＇ age class. Our results showed that the effect of wind on daily movement rates was not uniform, being stronger in the farthest region from the migration goal, the Sahara desert, with adults being more affected than juveniles in this region. In the Sahel, the results were more conflicting, perhaps because daily movements were more shaped by the distribution of food resources. In Equatorial Africa, daily movement rates were mainly af- fected by crosswinds. Still, it remains unclear which orientation mechanism allows Eleonora＇s falcons to reach such a narrow wintering area compensating also for wind displacement
基金supported by the National Natural Science Foundation of China (Grant No. 41072251)the State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, CAS (Grant No. 113106)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20123401110005)
文摘The Hengduan Mountains(henceforth H-D Mountains) on the Tibet Plateau are a distribution and diversity center for many alpine genera. We examine patterns of genetic variation in an arctic-alpine plant to evaluate the possibility that the H-D Mountains constitute the area of origin of the species as well as to uncover postglacial migration routes. 220 individuals of the arctic-alpine plant Koenigia islandica were sampled from 26 populations distributed in western China and northern Finland. DNA haplotypes were identified using restriction site analysis of two chloroplast DNA intergene spacer regions, atpB-rbcL and trnL-trnF. We examined the geographical distribution of haplotype diversity in relation to latitude, and also compared various indices of diversity in putatively glaciated and unglaciated regions. Patterns of migration were inferred using nested clade analysis. A total of 25 haplotypes were detected. High haplotype diversity was found in the H-D Mountains. H3 and its radiated haplotypes were distributed in the Himalayas. Two haplotypes were fixed concurrently in the H-D Mountains and northern Finland. High genetic diversity of K. islandica and high species diversity of K. islandica are expected in the origin area. Our observations suggest that the H-D Mountains are not only the place of origin of K. islandica, but also the refugia for K. islandica on the Tibet Plateau. What is more, the migration route for the arctic-alpine plant K. islandica must have originated in the region defined by the H-D Mountains in western China extending northward to the Arctic circumpolar, and moved westward along the Himalayas, then northward across the Altay Mountains and the Central Siberian Plateau at different time periods.
