Karl G. Johnson

ORCID: 0000-0003-3931-5985
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About
Contact & Profiles
Research Areas
  • Axon Guidance and Neuronal Signaling
  • Flood Risk Assessment and Management
  • Tropical and Extratropical Cyclones Research
  • Protein Tyrosine Phosphatases
  • Hippo pathway signaling and YAP/TAZ
  • Neurobiology and Insect Physiology Research
  • Developmental Biology and Gene Regulation
  • Neuroscience and Neuropharmacology Research
  • Retinal Development and Disorders
  • Cellular transport and secretion
  • Proteoglycans and glycosaminoglycans research
  • Cellular Mechanics and Interactions
  • Hydrology and Drought Analysis
  • Ubiquitin and proteasome pathways
  • Galectins and Cancer Biology
  • Plant and Biological Electrophysiology Studies
  • Milk Quality and Mastitis in Dairy Cows
  • Immunodeficiency and Autoimmune Disorders
  • Wnt/β-catenin signaling in development and cancer
  • Infectious Diseases and Mycology
  • Hydrology and Watershed Management Studies
  • Invertebrate Immune Response Mechanisms
  • Physiological and biochemical adaptations
  • Veterinary Orthopedics and Neurology
  • Veterinary Equine Medical Research

The University of Texas at Tyler
2018

University of Tennessee at Knoxville
2018

Sewanee: The University of the South
2018

Pomona College
2006-2018

University of Florida
2018

The University of Adelaide
2014

Harvard University
2003-2006

University of Cambridge
2000-2001

University of California, San Diego
1996

The heparan sulfate proteoglycan (HSPG) Syndecan (Sdc) is a crucial regulator of synapse development and growth in both vertebrates invertebrates. In Drosophila, Sdc binds via its extracellular (HS) sidechains to the receptor protein tyrosine phosphatase LAR promote morphological neuromuscular junction (NMJ). To date, however, little else known about molecular mechanisms by which functions growth. Here we show that all detectable found at NMJ provided muscle, strongly suggesting...

10.1371/journal.pone.0151621 article EN cc-by PLoS ONE 2016-03-17

Axon guidance is influenced by the presence of heparan sulfate (HS) proteoglycans (HSPGs) on surface axons and growth cones (Hu, [2001]: Nat Neurosci 4:695-701; Irie et al. [2002]: Development 129:61-70; Inatani [2003]: Science 302:1044-1046; Johnson [2004]: Curr Biol 14:499-504; Steigemann 14:225-230). Multiple HSPGs, including Syndecans, Glypicans Perlecans, carry same carbohydrate polymer backbones, raising question how these molecules display functional specificity during nervous system...

10.1002/dneu.20854 article EN Developmental Neurobiology 2011-04-16

Receptor protein tyrosine phosphatases (RPTPs) are regulators of axon outgrowth and guidance in a variety different vertebrate invertebrate systems. Three RPTPs, CRYP-alpha, PTP-delta, LAR, expressed overlapping but distinct patterns the developing Xenopus retina, including expression retinal ganglion cells (RGCs) as they send axons to tectum (Johnson KG, Holt CE. 2000. Expression PTP-rho visual system. Mech Dev 92:291-294). In order examine role these RPTPs system development, putative...

10.1002/neu.1068 article EN Journal of Neurobiology 2001-09-27

The receptor protein tyrosine phosphatase (PTPase) Dlar has an ectodomain consisting of three immunoglobulin (Ig)-like domains and nine fibronectin type III (FnIII) repeats a cytoplasmic domain two PTPase domains, membrane-proximal PTP-D1 C-terminal PTP-D2. A series mutant transgenes were introduced into the Drosophila genome via P-element transformation then assayed for their capacity to rescue phenotypes caused by homozygous loss-of-function genotypes. Ig-like but not FnIII are essential...

10.1128/mcb.23.19.6909-6921.2003 article EN Molecular and Cellular Biology 2003-09-12

This paper defines a collection of Drosophila deletion mutations (deficiencies) that can be systematically screened for embryonic phenotypes, orphan receptor ligands, and genes affecting protein localization. It reports the results deficiency screens we have conducted revealed new axon guidance phenotypes in central nervous system neuromuscular permitted quantitative assessment number potential involved regulating specific motor branches. Deficiency “kits” cover genome with minimum lines...

10.1371/journal.pone.0012288 article EN cc-by PLoS ONE 2010-08-19

Introduction Poll flexion may play an important role in the development of dynamic upper respiratory tract ( URT ) collapse. However, limited investigations have been performed Standardbred racehorses. Methods Eight Standardbreds were examined during training, once flexed and extension, using a randomised crossover design. Head position was maintained modified check‐reins head‐neck angle recorded. On each occasion horses 2 rounds exercise 2400 m at ∼35 km/h. Speed heart rate HR measured...

10.1111/evj.12267_67 article EN Equine Veterinary Journal 2014-06-01

Syndecan (Sdc) is a transmembrane heparan sulfate proteoglycan that plays crucial role in axon guidance and synapse formation during CNS development Drosophila melanogaster. To further examine the effect of syndecan on function, Sdc23 mutant D. melanogaster larvae were used to odor preference capacity for learning memory. A series olfaction assays both wild type performed characterize naive responses before adding training period identify associative learning. These results showed prefer...

10.33697/ajur.2018.009 article EN American Journal of Undergraduate Research 2018-06-22
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