Chitwan-Annapuma Landscape(CHAL)in central Nepal is known for its rich biodiversity and the landscape is expected to provide corridors for species range shift in response to climate change.Environmental assessments ha...Chitwan-Annapuma Landscape(CHAL)in central Nepal is known for its rich biodiversity and the landscape is expected to provide corridors for species range shift in response to climate change.Environmental assessments have identified biological invasions and other anthropogenic activities as major threats to the biodiversity in the CHAL.One of the rapidly spreading Invasive Alien Plant species(IAPs)in the CHAL is Parthenium hysterophorus L.,a neotropical invasive weed of global significance.This study aimed to investigate the current and future projected suitable habitat of P.hysterophorus in the CHAL using MaxEnt modelling in three'Representative Concentration Pathways'(RCPs 2.6,4.5 and 8.5)corresponding to different greenhouse gases emissiontrajectories for the year 2050 and 2070.A total of 288species occurrence points,six bioclimatic variablesmean diurnal range,isothermality,annual precipitation,precipitation of driest month,precipitation seasonality,precipitation of driest quarter and two topographic variables(aspect and slope)were selected for MaxEnt modelling.Potential range shift in terms of increase or decline in the suitable habitat areas under the projected scenarios were calculated.Slope and annual precipitation were the most important variables that explained the current distribution of P.hysterophorus.Twenty percent of the total area of CHAL was predicted to be suitable habitat for the growth of P.hysterophorus in the current climatic condition.Highest gain in the suitable habitat of this noxious weed was found under RCP 4.5 scenario in 2050 and 2070.whereas there will be a loss in thesuitable habitat under RCP 8.5 scenario in 2050 and2070.Out of four physiographic regions present in CHAL,three regions-Siwalik,Middle Mountain and High Mountain have suitable habitat for P.hysterophorus under current climatic condition.The mountainous region is likely to be affected more than the Siwalik region by further spread of P.fhysteropfhorus in the future under low(RCP 2.6)to medium(RCP 4.5)emission scenarios.The suitable habitat for this weed is likely to increase in the protected areas of mountain regions(Langtang National Park,Annapurna Conservation Area and Manaslu Conservation Area)in the future.The results have revealed a risk of spreading P.hysterophorus from present localities to non-invaded areas in the current and future climatic condition.Such risk needs to be considered by decision makers and resource managers while planning for effective management of this weed to reduce its ecological and economic impacts in the CHAL.展开更多
In vertebrate limb, a group of specialized epithelial cells called Apical Ectodermal Ridge (AER) form at the boundary of dorsal and ventral limb ectoderm. Recent experiments suggest that AER forms at the boundary of F...In vertebrate limb, a group of specialized epithelial cells called Apical Ectodermal Ridge (AER) form at the boundary of dorsal and ventral limb ectoderm. Recent experiments suggest that AER forms at the boundary of Fringe expressing and Fringe non-expressing cells by a specific type of receptor-ligand interaction called as inductive signaling, involving the transmembrane proteins Notch, Serrate and Delta. Experiments conducted on Drosophila wing disc have shown that Fringe inhibits the binding ability of Serrate ligand to Notch and enhances that of Delta to Notch. Although several of the signaling elements have been identified experimentally, it remains unclear how the inter-cellular interactions can give rise to such a boundary of specialized cells. Here we present an ordinary differential equation (ODE) model involving Delta→Notch and Serrate→Notch interactions between juxtaposed Fringe expressing and Fringe nonexpressing cells. When simulated in a compartmentalized set up, this model gives rise to high Notch levels at the boundary of Fringe expressing and Fringe non-expressing cells.展开更多
The Human Genome Project(HGP)is a historical and landmark scientific project.In spite of initial controversy it has become a bedrock foundation for much progress in biological science and human health.After the Human ...The Human Genome Project(HGP)is a historical and landmark scientific project.In spite of initial controversy it has become a bedrock foundation for much progress in biological science and human health.After the Human Genome Project was completed in the early 2000s,next generation sequencing technologies were developed and that has revolutionized genomics.Here is a brief account of the May 1985 meeting at University of California Santa Cruz.Historical accounts often begin with a the Department of Energy(DOE)meeting in Santa Fe in March 1986 and neglect including the Santa Cruz meeting[1],although sometimes it is discussed[2].展开更多
基金support provided by the Feed the Future Innovation Lab for Integrated Pest Management of the U.S. Agency for International Development, under the terms of Cooperative Agreement No. AID–OAA-L-15-00001supported by International Foundation for Science (Sweden), Nepal Academy of Science and Technology (Nepal), and National Trust for Nature Conservation (Nepal)
文摘Chitwan-Annapuma Landscape(CHAL)in central Nepal is known for its rich biodiversity and the landscape is expected to provide corridors for species range shift in response to climate change.Environmental assessments have identified biological invasions and other anthropogenic activities as major threats to the biodiversity in the CHAL.One of the rapidly spreading Invasive Alien Plant species(IAPs)in the CHAL is Parthenium hysterophorus L.,a neotropical invasive weed of global significance.This study aimed to investigate the current and future projected suitable habitat of P.hysterophorus in the CHAL using MaxEnt modelling in three'Representative Concentration Pathways'(RCPs 2.6,4.5 and 8.5)corresponding to different greenhouse gases emissiontrajectories for the year 2050 and 2070.A total of 288species occurrence points,six bioclimatic variablesmean diurnal range,isothermality,annual precipitation,precipitation of driest month,precipitation seasonality,precipitation of driest quarter and two topographic variables(aspect and slope)were selected for MaxEnt modelling.Potential range shift in terms of increase or decline in the suitable habitat areas under the projected scenarios were calculated.Slope and annual precipitation were the most important variables that explained the current distribution of P.hysterophorus.Twenty percent of the total area of CHAL was predicted to be suitable habitat for the growth of P.hysterophorus in the current climatic condition.Highest gain in the suitable habitat of this noxious weed was found under RCP 4.5 scenario in 2050 and 2070.whereas there will be a loss in thesuitable habitat under RCP 8.5 scenario in 2050 and2070.Out of four physiographic regions present in CHAL,three regions-Siwalik,Middle Mountain and High Mountain have suitable habitat for P.hysterophorus under current climatic condition.The mountainous region is likely to be affected more than the Siwalik region by further spread of P.fhysteropfhorus in the future under low(RCP 2.6)to medium(RCP 4.5)emission scenarios.The suitable habitat for this weed is likely to increase in the protected areas of mountain regions(Langtang National Park,Annapurna Conservation Area and Manaslu Conservation Area)in the future.The results have revealed a risk of spreading P.hysterophorus from present localities to non-invaded areas in the current and future climatic condition.Such risk needs to be considered by decision makers and resource managers while planning for effective management of this weed to reduce its ecological and economic impacts in the CHAL.
文摘In vertebrate limb, a group of specialized epithelial cells called Apical Ectodermal Ridge (AER) form at the boundary of dorsal and ventral limb ectoderm. Recent experiments suggest that AER forms at the boundary of Fringe expressing and Fringe non-expressing cells by a specific type of receptor-ligand interaction called as inductive signaling, involving the transmembrane proteins Notch, Serrate and Delta. Experiments conducted on Drosophila wing disc have shown that Fringe inhibits the binding ability of Serrate ligand to Notch and enhances that of Delta to Notch. Although several of the signaling elements have been identified experimentally, it remains unclear how the inter-cellular interactions can give rise to such a boundary of specialized cells. Here we present an ordinary differential equation (ODE) model involving Delta→Notch and Serrate→Notch interactions between juxtaposed Fringe expressing and Fringe nonexpressing cells. When simulated in a compartmentalized set up, this model gives rise to high Notch levels at the boundary of Fringe expressing and Fringe non-expressing cells.
文摘The Human Genome Project(HGP)is a historical and landmark scientific project.In spite of initial controversy it has become a bedrock foundation for much progress in biological science and human health.After the Human Genome Project was completed in the early 2000s,next generation sequencing technologies were developed and that has revolutionized genomics.Here is a brief account of the May 1985 meeting at University of California Santa Cruz.Historical accounts often begin with a the Department of Energy(DOE)meeting in Santa Fe in March 1986 and neglect including the Santa Cruz meeting[1],although sometimes it is discussed[2].
