more information
Search within Results:

Select All    Deselect All
 |   | 
Details
   print
  Records Links
Author (up) Alvarez, J.; Fadic, R. file  url
openurl 
  Title Assembly and disassembly of axonal microtubules of the toad Xenopus laevis under the effect of temperature Type Journal Article
  Year 1992 Publication The Journal of Experimental Zoology Abbreviated Journal J Exp Zool  
  Volume 264 Issue 3 Pages 261-266  
  Keywords Animals; Axons/*physiology; Cytoplasm/metabolism; Kinetics; Microtubules/*physiology; Seasons; *Temperature; Tubulin/metabolism; Xenopus laevis  
  Abstract In toads Xenopus laevis living at 11 degrees (winter), the microtubular density of 4-microns myelinated axons of lumbosacral nerves was assessed with the electron microscope. In controls, the density was 11.2 microtubules/microns2. In nerves incubated at 0 degrees, microtubules decreased following a simple exponential curve with a half time of 4.7 min (k = 0.149 min-1); residual microtubules were 4.5%. After rewarming, the full complement of microtubules reappeared within 60 min. In steady state, the microtubular density exhibited a linear relationship with temperature (range: 0-22 degrees; slope 0.94 microtubules/microns 2 per degree; r, 0.96). After heating the nerve by 11 degrees above the physiological temperature, microtubules increased by 83%, whereby the pool of unpolymerized tubulin was at least 2.7 mg/ml of axoplasm. A seasonal variation of the microtubular density was observed which accorded with the environmental temperature. The macroscopic kinetics of microtubule disassembly in the axoplasm is similar to that reported for purified tubulin but that of assembly is slower. Microtubules of peripheral axons of Xenopus are cold-labile and vary during the annual cycle.  
  Call Number Serial 1174  
Permanent link to this record
 

 
Author (up) Chou, S.M.; Wang, H.S.; Komai, K. file  url
openurl 
  Title Colocalization of NOS and SOD1 in neurofilament accumulation within motor neurons of amyotrophic lateral sclerosis: an immunohistochemical study Type Journal Article
  Year 1996 Publication Journal of Chemical Neuroanatomy Abbreviated Journal J Chem Neuroanat  
  Volume 10 Issue 3-4 Pages 249-258  
  Keywords Amyotrophic Lateral Sclerosis/*enzymology; Citrulline/metabolism; Cyclic GMP/metabolism; Cytoplasm/metabolism; Humans; Immunohistochemistry; Motor Neurons/chemistry/*enzymology; Neurofilament Proteins/*metabolism; Nitrates/metabolism; Nitric Oxide/analysis/*metabolism; Nitrogen/metabolism; Oxidation-Reduction; Superoxide Dismutase/analysis/*metabolism; Tyrosine/metabolism  
  Abstract Peroxynitrite, formed from nitric oxide and superoxide, may affect neurofilament assembly and cause neurofilament accumulation in motoneurons. This hypothesis may reconcile the mutations of two genes: superoxide dismutase-1 in some patients with familial amyotrophic lateral sclerosis, and the gene for the heavy neurofilament in some patients with sporadic amyotrophic lateral sclerosis previously reported. We found colocalization of superoxide dismutase-1 and nitric oxide synthase in the foci of neurofilament accumulation as 'conglomerates' in upper motor neurons and 'axonal spheroids' in lower motor neurons. In addition, all the specific molecules related to the reactions, including calmodulin, 3', 5'-cyclic guanosine-monophosphate, citrulline, and nitrotyrosine were found strongly immunopositive in the site of neurofilament accumulation. Our data support the view that the neurofilament aggregates are tightly linked with superoxide dismutase-1 and nitric oxide synthase activities. Both enzymes may focally contribute to peroxynitrite formation at light neurofilament, which is rich in both tyrosine and arginine residues and hence considered as the vulnerable site for nitrotyrosine formation. Nitrotyrosine is known to inhibit phosphorylation and if it impairs phosphorylation of neurofilament subunits, either light or heavy, may alter the slow axonal transport culminating in proximo-distal accumulation of NF and slowly progressive motoneuron death.  
  Call Number Serial 1254  
Permanent link to this record
 

 
Author (up) Yuan, W.; Parrish, C.R. file  url
doi  openurl
  Title Canine parvovirus capsid assembly and differences in mammalian and insect cells Type Journal Article
  Year 2001 Publication Virology Abbreviated Journal Virology  
  Volume 279 Issue 2 Pages 546-557  
  Keywords Animals; Baculoviridae/genetics; Capsid/*physiology; Cell Line; Cell Nucleus/metabolism; Cytoplasm/metabolism; Dogs; Electrophoresis, Polyacrylamide Gel; Fluorescent Antibody Technique; Hydrogen-Ion Concentration; Mammals; Mutation; Parvovirus, Canine/genetics/*physiology; Recombinant Proteins/biosynthesis; Spodoptera; Time Factors; Transfection; Urea/pharmacology; Viral Proteins/biosynthesis/genetics; *Virus Assembly/drug effects  
  Abstract We examined the assembly processes of the capsid proteins of canine parvovirus (CPV) in mammalian and insect cells. In CPV-infected cells empty capsids assembled within 15 min, and then continued to form over the following 1 h, while full (DNA-containing) capsids were detected only after 60 min, and those accumulated slowly over several hours. In cells expressing VP1 and VP2 or only VP2, empty capsid formation was also efficient, but was slightly slower than that in infected cells. Small amounts of trimer forms of VP2 were detected in cells expressing wild type capsid proteins, but were not seen for mutants containing changes that prevented capsid assembly. CPV capsids accumulated in the cell nucleus, but mutant VP1 and VP2 proteins that did not assemble became distributed throughout the nucleus and the cytoplasm, irrespective of whether they were expressed as VP1 and VP2, or as VP2 only. Urea or pH treatment of empty capsids released dimer, trimer, or pentamer capsid protein combinations, while treatment of full capsids consistently released trimer and, in some cases, pentamer forms. When wild type or assembly-defective VP2 genes were expressed from recombinant baculoviruses in insect cells, most of the protein was recovered as noncapsid aggregates, and only a small proportion assembled into capsids. Both the assembled capsids and the noncapsid aggregates were seen primarily in the cytoplasm of the insect cells. The VP2 expressed in insect cells that was recovered in aggregates had an isoelectric point of about pH 6.3, while that recovered from assembled capsids had a pI of about 5.2, similar to that seen for the VP2 of capsids recovered from mammalian cells.  
  Call Number Serial 162  
Permanent link to this record
Select All    Deselect All
 |   | 
Details
   print

Save Citations: