Effect of heat on frog sciatic nerve determined by X-ray diffraction

Worthington, C.R.; Worthington, A.R.

doi:10.1016/0141-8130(81)90057-x

Cited by 7 publications

(4 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The effect of temperature, freezing and drying has been extensively studied in the literature , see e.g. [29,[32][33][34][35] and references therein, however, the values reported in the references cannot be directly compared to the values reported here, primarily because the extracted nerve was typically re-immersed in a buffer solution after freezing or heating. Therefore, future extension of this work has to investigate whether myelin is indeed capable of forming hexatic phases.…”

Section: (B))mentioning

confidence: 99%

Imaging of neuronal tissues by x-ray diffraction and x-ray fluorescence microscopy: evaluation of contrast and biomarkers for neurodegenerative diseases

Carboni

Nicolas

Töpperwien

et al. 2017

Biomed. Opt. Express

View full text Add to dashboard Cite

We have used scanning X-ray diffraction (XRD) and X-ray fluorescence (XRF) with micro-focused synchrotron radiation to study histological sections from human substantia nigra (SN). Both XRF and XRD mappings visualize tissue properties, which are inaccessible by conventional microscopy and histology. We propose to use these advanced tools to characterize neuronal tissue in neurodegeneration, in particular in Parkinson's disease (PD). To this end, we take advantage of the recent experimental progress in x-ray focusing, detection, and use automated data analysis scripts to enable quantitative analysis of large field of views. XRD signals are recorded and analyzed both in the regime of small-angle (SAXS) and wide-angle x-ray scattering (WAXS). The SAXS signal was analyzed in view of the local myelin structure, while WAXS was used to identify crystalline deposits. PD tissue scans exhibited increased amounts of crystallized cholesterol. The XRF analysis showed increased amounts of iron and decreased amounts of copper in the PD tissue compared to the control.

show abstract

Section: (B))mentioning

confidence: 99%

Imaging of neuronal tissues by x-ray diffraction and x-ray fluorescence microscopy: evaluation of contrast and biomarkers for neurodegenerative diseases

Carboni

Nicolas

Töpperwien

et al. 2017

Biomed. Opt. Express

View full text Add to dashboard Cite

show abstract

“…X-ray diffraction has been used to probe the interactions that stabilize the normal, orderly packing of myelin membranes by examining myelin structure in nerves which have been subjected to a variety of physical-chemical treatments. Such treatments involve changes in ionic strength (Finean and Millington, 1957;Robertson, 1958;Worthington and Blaurock, 1969), pH (Worthington, 1979), water content (Finean, 1961;Kirschner and Caspar, 1975), and temperature (Worthington and Worthington, 1981), and also exposure to chemical reagents (see reviews by Rumsby andCrang, 1977, andKirschner et al, 1984). The changes in myelin period which result from these treatments have been summarized (Worthington, 1982;Kirschner et al, 1984), and the involvement of surface charge in determining membrane packing in myelin has been suggested (Worthington and Blaurock, 1969).…”

Section: Introductionmentioning

confidence: 99%

Membrane interactions in nerve myelin. I. Determination of surface charge from effects of pH and ionic strength on period

Inouye

Kirschner

1988

Biophysical Journal

104

View full text Add to dashboard Cite

We have used x-ray diffraction to study the interactions between myelin membranes in the sciatic nerve (PNS) and optic nerve (CNS) as a function of pH (2-10) and ionic strength (0-0.18). The period of myelin was found to change in a systematic manner with pH and ionic strength. PNS periods ranged from 165 to 250 A or more, while CNS periods ranged from 150 to 230 A. The native periods were observed only near physiological ionic strength at neutral or alkaline pH. The smallest periods were observed in the pH range 2.5-4 for PNS myelin and pH 2.5-5 for CNS myelin. The minimum period was also observed for PNS myelin after prolonged incubation in distilled water. At pH 4, within these acidic pH ranges, myelin period increased slightly with ionic strength; however, above these ranges, the period increased with pH and decreased with ionic strength. Electron density profiles calculated at different pH and ionic strength showed that the major structural alteration underlying the changes in period was in the width of the aqueous space at the extracellular apposition of membranes; the width of the cytoplasmic space was virtually constant. Assuming that the equilibrium myelin periods are determined by a balance of nonspecific forces/i.e., the electrostatic repulsion force and the van der Walls attractive force, as well as the short-range repulsion force (hydration force, or steric stabilization), then values in the period-dependency curve can be used to define the isoelectric pH and exclusion length of the membrane. The exclusion length, which is related to the minimum period at isoelectric pH, was used to calculate the electrostatic repulsion force given the other forces. The electrostatic repulsion was then used to calculate the surface potential, which in turn was used to calculate the surface charge density (at different pH and ionic strength). We found the negative surface charge increases with pH at constant ionic strength and with ionic strength at constant pH. We suggest that the former is due to deprotonation of the ionizable groups on the surface while the latter is due to ion binding. Interpretation of our data in terms of the chemical composition of myelin is given in the accompanying paper (Inouye and Kirschner, 1988). We also calculated the total potential energy functions for the different equilibrium periods and found that the energy minima became shallower and broader with increasing membrane separation. Finally, it was difficult to account directly for certain structural transitions from a balance of nonspecific forces. Such transitions included the abrupt appearance of the native period at alkaline pH and physiological ionic strength and the discontinuous compaction after prolonged treatment in distilled water. Possibly, in PNS myelin conformational modification of PO glycoprotein occurs under these conditions. The invariance of the cytoplasmic space suggests the presence of specific short-range interactions between surfaces at this apposition.

show abstract

“…However, the behavior of myelin under conditions of moderate cooling (4–15°C) has remained vastly unexplored [ 14 , 15 ], despite its great relevance for DIGs and DRMs isolation, at those temperatures. A few studies on nerve myelin dealt with the effect of heating [ 16 , 17 ]. In a study on the effect of cooling, wide-angle X-ray scattering (WAXS) measurements revealed that myelin lipid acyl chains remain in a disordered state down to low temperatures, as long as the hydration water is still liquid (above -10°C), and chain crystalline ordering is only observed under conditions of frozen hydration water [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

Cooling induces phase separation in membranes derived from isolated CNS myelin

Pusterla

Schneck

Funari³

et al. 2017

PLoS ONE

View full text Add to dashboard Cite

Purified myelin membranes (PMMs) are the starting material for biochemical analyses such as the isolation of detergent-insoluble glycosphingolipid-rich domains (DIGs), which are believed to be representatives of functional lipid rafts. The normal DIGs isolation protocol involves the extraction of lipids under moderate cooling. Here, we thus address the influence of cooling on the structure of PMMs and its sub-fractions. Thermodynamic and structural aspects of periodic, multilamellar PMMs are examined between 4°C and 45°C and in various biologically relevant aqueous solutions. The phase behavior is investigated by small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC). Complementary neutron diffraction (ND) experiments with solid-supported myelin multilayers confirm that the phase behavior is unaffected by planar confinement. SAXS and ND consistently show that multilamellar PMMs in pure water become heterogeneous when cooled by more than 10–15°C below physiological temperature, as during the DIGs isolation procedure. The heterogeneous state of PMMs is stabilized in physiological solution, where phase coexistence persists up to near the physiological temperature. This result supports the general view that membranes under physiological conditions are close to critical points for phase separation. In presence of elevated Ca2+ concentrations (> 10 mM), phase coexistence is found even far above physiological temperatures. The relative fractions of the two phases, and thus presumably also their compositions, are found to vary with temperature. Depending on the conditions, an “expanded” phase with larger lamellar period or a “compacted” phase with smaller lamellar period coexists with the native phase. Both expanded and compacted periods are also observed in DIGs under the respective conditions. The observed subtle temperature-dependence of the phase behavior of PMMs suggests that the composition of DIGs is sensitive to the details of the isolation protocol.

show abstract

Effect of heat on frog sciatic nerve determined by X-ray diffraction

Cited by 7 publications

References 16 publications

Imaging of neuronal tissues by x-ray diffraction and x-ray fluorescence microscopy: evaluation of contrast and biomarkers for neurodegenerative diseases

Imaging of neuronal tissues by x-ray diffraction and x-ray fluorescence microscopy: evaluation of contrast and biomarkers for neurodegenerative diseases

Membrane interactions in nerve myelin. I. Determination of surface charge from effects of pH and ionic strength on period

Cooling induces phase separation in membranes derived from isolated CNS myelin

Contact Info

Product

Resources

About