Christopher J. Johnson, PhD
Dr. Christopher Johnson is the Acting Director for the Office of Science Quality and Integrity (OSQI) at the U.S. Geological Survey (USGS), which is responsible for enhancing the integrity, quality, and health of USGS science.
In this role, Dr. Johnson is tasked with enhancing the integrity, quality, and health of USGS science through oversight of laboratory sciences, Tribal relations, youth and education, research grade evaluations, science quality, scientific integrity, and fundamental science practices.
Science and Products
Filter Total Items: 20
Plants as vectors for environmental prion transmission
Prions cause fatal neurodegenerative diseases and exhibit remarkable durability, which engenders a wide array of potential exposure scenarios. In chronic wasting disease of deer, elk, moose, and reindeer and in scrapie of sheep and goats, prions are transmitted via environmental routes and the ability of plants to accumulate and subsequently transmit prions has been hypothesized, but not...
Authors
Christina M. Carlson, Samuel Thomas, Matthew W. Keating, Nicole M. Gibbs, Haeyoon Chang, Jamie K. Wiepz, Annabel G. Austin, Jay R. Schneider, Christopher J. Johnson, Joel A. Pedersen
Increased attack rates and decreased incubation periods in raccoons with chronic wasting disease passaged through meadow voles
Chronic wasting disease (CWD) is a naturally-occurring neurodegenerative disease of cervids. Raccoons (Procyon lotor) and meadow voles (Microtus pennsylvanicus) have previously been shown to be susceptible to the CWD agent. To investigate the potential for transmission of the agent of CWD from white-tailed deer to voles and subsequently to raccoons, we intracranially inoculated raccoons...
Authors
S. L. Moore, Christina M. Carlson, Jay R. Schneider, Christopher J. Johnson, Justin J. Greenlee
Peak ground velocity spatial variability revealed by dense seismic array in southern California
Understanding and modeling variability of ground motion is essential for building accurate and precise ground motion prediction equations, which can net site‐specific characterization and reduced hazard levels. Here, we explore the spatial variability in peak ground velocity (PGV) at Sage Brush Flats along the San Jacinto Fault in southern California. We use data from a dense array (0.6...
Authors
Christopher J. Johnson, Deborah L. Kilb, Annemarie S. Baltay Sundstrom, Frank L. Vernon
Chronic wasting disease—Research by the U.S. Geological Survey and partners
IntroductionChronic wasting disease (CWD) is the only transmissible spongiform encephalopathy, a class of invariably fatal neurodegenerative mammalian diseases associated with a misfolded cellular prion protein found in wild free-ranging animals. Because it has a long incubation period, affected animals in Cervidae (the deer family; referred to as “cervids”) may not show signs of disease...
Authors
M. Camille Hopkins, Christina M. Carlson, Paul C. Cross, Christopher J. Johnson, Bryan J. Richards, Robin E. Russell, Michael Samuel, Glen A. Sargeant, Daniel P. Walsh, W. David Walter
Interseismic ground deformation and fault slip rates in the greater San Francisco Bay Area from two decades of space geodetic data
The detailed spatial variations of strain accumulation and creep on major faults in the northern San Francisco Bay Area (North Bay), which are important for seismic potential and evaluation of natural hazards, remain poorly understood. Here we combine interferometric synthetic aperture radar data from the ERS‐1/2 and Envisat satellites between 1992 and 2010 with continuous and campaign...
Authors
Wenbin Xu, Songbo Wu, Kathryn Zerbe Materna, Robert Nadeau, Michael Floyd, Gareth J. Funning, Estelle Chaussard, Christopher J. Johnson, Jessica R. Murray, Xiaoling Ding, Roland Burgmann
Kinematics of the 2015 San Ramon, California earthquake swarm: Implications for fault zone structure and driving mechanisms
Earthquake swarms represent a sudden increase in seismicity that may indicate a heterogeneous fault-zone, the involvement of crustal fluids and/or slow fault slip. Swarms sometimes precede major earthquake ruptures. An earthquake swarm occurred in October 2015 near San Ramon, California in an extensional right step-over region between the northern Calaveras Fault and the Concord–Mt...
Authors
Lian Xue, Roland Burgmann, David R. Shelly, Christopher J. Johnson, Taka'aki Taira
Shallow microearthquakes near Chongqing, China triggered by the Rayleigh waves of the 2015 M7.8 Gorkha, Nepal earthquake
We present a case of remotely triggered seismicity in Southwest China by the 2015/04/25 M7.8 Gorkha, Nepal earthquake. A local magnitude ML3.8 event occurred near the Qijiang district south of Chongqing city approximately 12 min after the Gorkha mainshock. Within 30km of this ML3.8 event there are 62 earthquakes since 2009 and only 7 ML>3events, which corresponds to a likelihood of 0.3%...
Authors
Libo Han, Zhigang Peng, Christopher J. Johnson, Frederick Pollitz, Lu Li, Baoshan Wang, Jing Wu, Qiang Li, Hongmei Wei
Assessing transmissible spongiform encephalopathy species barriers with an in vitro prion protein conversion assay
Studies to understanding interspecies transmission of transmissible spongiform encephalopathies (TSEs, prion diseases) are challenging in that they typically rely upon lengthy and costly in vivo animal challenge studies. A number of in vitro assays have been developed to aid in measuring prion species barriers, thereby reducing animal use and providing quicker results than animal...
Authors
Christopher J. Johnson, Christina M. Carlson, Aaron R. Morawski, Alyson Manthei, Neil R. Cashman
Experimental infection of meadow voles (Microtus pennsylvanicus) with sheep scrapie
Meadow voles (Microtus pennsylvanicus) are permissive to chronic wasting disease (CWD) infection, but their susceptibility to other transmissible spongiform encephalopathies (TSEs) is poorly characterized. In this initial study, we intracerebrally challenged 6 meadow voles with 2 isolates of sheep scrapie. Three meadow voles acquired a TSE after the scrapie challenge and an extended...
Authors
CM Carlson, Jay R. Schneider, Janice C. Pedersen, Dennis M. Heisey, Christopher J. Johnson
Humic substances interfere with detection of pathogenic prion protein
Studies examining the persistence of prions (the etiological agent of transmissible spongiform encephalopathies) in soil require accurate quantification of pathogenic prion protein (PrPTSE) extracted from or in the presence of soil particles. Here, we demonstrate that natural organic matter (NOM) in soil impacts PrPTSE detection by immunoblotting. Methods commonly used to extract PrPTSE...
Authors
Christen B. Smith, Clarissa J. Booth, Tyler J. Wadzinski, Giuseppe Legname, Rick Chappell, Christopher J. Johnson, Joel A. Pedersen
Low copper and high manganese levels in prion protein plaques
Accumulation of aggregates rich in an abnormally folded form of the prion protein characterize the neurodegeneration caused by transmissible spongiform encephalopathies (TSEs). The molecular triggers of plaque formation and neurodegeneration remain unknown, but analyses of TSE-infected brain homogenates and preparations enriched for abnormal prion protein suggest that reduced levels of...
Authors
Christopher J. Johnson, P.U.P.A. Gilbert, Mike Abrecth, Katherine L. Baldwin, Robin E. Russell, Joel A. Pedersen, Debbie I. McKenzie
In vitro prion protein conversion suggests risk of bighorn sheep (Ovis canadensis) to transmissible spongiform encephalopathies
Background: Transmissible spongiform encephalopathies (TSEs) affect both domestic sheep (scrapie) and captive and free-ranging cervids (chronic wasting disease; CWD). The geographical range of bighorn sheep (Ovis canadensis; BHS) overlaps with states or provinces that have contained scrapie-positive sheep or goats and areas with present epizootics of CWD in cervids. No TSEs have been...
Authors
Christopher J. Johnson, Aaron R. Morawski, CM Carlson, H. Chang
Science and Products
Filter Total Items: 20
Plants as vectors for environmental prion transmission
Prions cause fatal neurodegenerative diseases and exhibit remarkable durability, which engenders a wide array of potential exposure scenarios. In chronic wasting disease of deer, elk, moose, and reindeer and in scrapie of sheep and goats, prions are transmitted via environmental routes and the ability of plants to accumulate and subsequently transmit prions has been hypothesized, but not...
Authors
Christina M. Carlson, Samuel Thomas, Matthew W. Keating, Nicole M. Gibbs, Haeyoon Chang, Jamie K. Wiepz, Annabel G. Austin, Jay R. Schneider, Christopher J. Johnson, Joel A. Pedersen
Increased attack rates and decreased incubation periods in raccoons with chronic wasting disease passaged through meadow voles
Chronic wasting disease (CWD) is a naturally-occurring neurodegenerative disease of cervids. Raccoons (Procyon lotor) and meadow voles (Microtus pennsylvanicus) have previously been shown to be susceptible to the CWD agent. To investigate the potential for transmission of the agent of CWD from white-tailed deer to voles and subsequently to raccoons, we intracranially inoculated raccoons...
Authors
S. L. Moore, Christina M. Carlson, Jay R. Schneider, Christopher J. Johnson, Justin J. Greenlee
Peak ground velocity spatial variability revealed by dense seismic array in southern California
Understanding and modeling variability of ground motion is essential for building accurate and precise ground motion prediction equations, which can net site‐specific characterization and reduced hazard levels. Here, we explore the spatial variability in peak ground velocity (PGV) at Sage Brush Flats along the San Jacinto Fault in southern California. We use data from a dense array (0.6...
Authors
Christopher J. Johnson, Deborah L. Kilb, Annemarie S. Baltay Sundstrom, Frank L. Vernon
Chronic wasting disease—Research by the U.S. Geological Survey and partners
IntroductionChronic wasting disease (CWD) is the only transmissible spongiform encephalopathy, a class of invariably fatal neurodegenerative mammalian diseases associated with a misfolded cellular prion protein found in wild free-ranging animals. Because it has a long incubation period, affected animals in Cervidae (the deer family; referred to as “cervids”) may not show signs of disease...
Authors
M. Camille Hopkins, Christina M. Carlson, Paul C. Cross, Christopher J. Johnson, Bryan J. Richards, Robin E. Russell, Michael Samuel, Glen A. Sargeant, Daniel P. Walsh, W. David Walter
Interseismic ground deformation and fault slip rates in the greater San Francisco Bay Area from two decades of space geodetic data
The detailed spatial variations of strain accumulation and creep on major faults in the northern San Francisco Bay Area (North Bay), which are important for seismic potential and evaluation of natural hazards, remain poorly understood. Here we combine interferometric synthetic aperture radar data from the ERS‐1/2 and Envisat satellites between 1992 and 2010 with continuous and campaign...
Authors
Wenbin Xu, Songbo Wu, Kathryn Zerbe Materna, Robert Nadeau, Michael Floyd, Gareth J. Funning, Estelle Chaussard, Christopher J. Johnson, Jessica R. Murray, Xiaoling Ding, Roland Burgmann
Kinematics of the 2015 San Ramon, California earthquake swarm: Implications for fault zone structure and driving mechanisms
Earthquake swarms represent a sudden increase in seismicity that may indicate a heterogeneous fault-zone, the involvement of crustal fluids and/or slow fault slip. Swarms sometimes precede major earthquake ruptures. An earthquake swarm occurred in October 2015 near San Ramon, California in an extensional right step-over region between the northern Calaveras Fault and the Concord–Mt...
Authors
Lian Xue, Roland Burgmann, David R. Shelly, Christopher J. Johnson, Taka'aki Taira
Shallow microearthquakes near Chongqing, China triggered by the Rayleigh waves of the 2015 M7.8 Gorkha, Nepal earthquake
We present a case of remotely triggered seismicity in Southwest China by the 2015/04/25 M7.8 Gorkha, Nepal earthquake. A local magnitude ML3.8 event occurred near the Qijiang district south of Chongqing city approximately 12 min after the Gorkha mainshock. Within 30km of this ML3.8 event there are 62 earthquakes since 2009 and only 7 ML>3events, which corresponds to a likelihood of 0.3%...
Authors
Libo Han, Zhigang Peng, Christopher J. Johnson, Frederick Pollitz, Lu Li, Baoshan Wang, Jing Wu, Qiang Li, Hongmei Wei
Assessing transmissible spongiform encephalopathy species barriers with an in vitro prion protein conversion assay
Studies to understanding interspecies transmission of transmissible spongiform encephalopathies (TSEs, prion diseases) are challenging in that they typically rely upon lengthy and costly in vivo animal challenge studies. A number of in vitro assays have been developed to aid in measuring prion species barriers, thereby reducing animal use and providing quicker results than animal...
Authors
Christopher J. Johnson, Christina M. Carlson, Aaron R. Morawski, Alyson Manthei, Neil R. Cashman
Experimental infection of meadow voles (Microtus pennsylvanicus) with sheep scrapie
Meadow voles (Microtus pennsylvanicus) are permissive to chronic wasting disease (CWD) infection, but their susceptibility to other transmissible spongiform encephalopathies (TSEs) is poorly characterized. In this initial study, we intracerebrally challenged 6 meadow voles with 2 isolates of sheep scrapie. Three meadow voles acquired a TSE after the scrapie challenge and an extended...
Authors
CM Carlson, Jay R. Schneider, Janice C. Pedersen, Dennis M. Heisey, Christopher J. Johnson
Humic substances interfere with detection of pathogenic prion protein
Studies examining the persistence of prions (the etiological agent of transmissible spongiform encephalopathies) in soil require accurate quantification of pathogenic prion protein (PrPTSE) extracted from or in the presence of soil particles. Here, we demonstrate that natural organic matter (NOM) in soil impacts PrPTSE detection by immunoblotting. Methods commonly used to extract PrPTSE...
Authors
Christen B. Smith, Clarissa J. Booth, Tyler J. Wadzinski, Giuseppe Legname, Rick Chappell, Christopher J. Johnson, Joel A. Pedersen
Low copper and high manganese levels in prion protein plaques
Accumulation of aggregates rich in an abnormally folded form of the prion protein characterize the neurodegeneration caused by transmissible spongiform encephalopathies (TSEs). The molecular triggers of plaque formation and neurodegeneration remain unknown, but analyses of TSE-infected brain homogenates and preparations enriched for abnormal prion protein suggest that reduced levels of...
Authors
Christopher J. Johnson, P.U.P.A. Gilbert, Mike Abrecth, Katherine L. Baldwin, Robin E. Russell, Joel A. Pedersen, Debbie I. McKenzie
In vitro prion protein conversion suggests risk of bighorn sheep (Ovis canadensis) to transmissible spongiform encephalopathies
Background: Transmissible spongiform encephalopathies (TSEs) affect both domestic sheep (scrapie) and captive and free-ranging cervids (chronic wasting disease; CWD). The geographical range of bighorn sheep (Ovis canadensis; BHS) overlaps with states or provinces that have contained scrapie-positive sheep or goats and areas with present epizootics of CWD in cervids. No TSEs have been...
Authors
Christopher J. Johnson, Aaron R. Morawski, CM Carlson, H. Chang