scholarly journals Conformational change in the outer doublet microtubules from sea urchin sperm flagella.

1979 ◽  
Vol 81 (2) ◽  
pp. 355-360 ◽  
Author(s):  
T Miki-Noumura ◽  
R Kamiya
Keyword(s):  
Sea Urchin ◽  
Conformational Changes ◽  
Helical Structure ◽  
Dark Field ◽  
Ion Concentration ◽  
Wave Form ◽  
Buffer System ◽  
Left Handed ◽  
Dark Field Microscopy ◽  
Hemicentrotus Pulcherrimus

Dark-field microscopy with a high-powered light source revealed that the outer doublet microtubules (DMTs) from sea urchin (Pseudocentrotus depressus and Hemicentrotus pulcherrimus) sperm flagella assume helically coiled configurations (Miki-Noumura, T., and R. Kamiya. 1976. Exp. Cell Res. 97: 451.). We report here that the DMTs change shape when the pH or Ca-ion concentration is changed. The DMTs assumed a left-handed helical shape with a diameter of 3.7 +/- 0.5 micron and a pitch of 2.8 +/- 0.7 micron at pH 7.4 in the presence of 0.1 mM CaCl2, 1 mM MgSO4, and 10 mM Tris-HCl. When the pH was raised to 8.3, the helical diameter and pitch decreased to 2.1 +/- 0.1 micron and 1.3 +/- 0.3 micron, respectively. This transformation was a rapid and reversible process and was completed within 1 min. Between pH 7.2 and 8.3, the DMTs assumed intermediate shapes. When the Ca-ion concentration was depleted with EGTA, the helical structure became significantly larger in both pitch and diameter. For instance, the diameter was 3.8 +/- 0.4 micron at pH 8.3 in the presence of 1 mM EGTA and 2 mM MgSO4. Using a Ca-buffer system, we obtained results which suggested that this Ca-induced transformation took place at a Ca concentration of approximately 10(-7) M. These results were highly reproducible. The conformational changes in the DMT may play some role in the bending wave form of flagellar movement.

WITHDRAWN: Microsecond resolution of enzymatic conformational changes using dark-field microscopy

Methods ◽  
2008 ◽  
Author(s):  
David Spetzler ◽  
Justin York ◽  
James Martin ◽  
Robert Ishmukhametov ◽  
Wayne D. Frasch
Keyword(s):  
Conformational Changes ◽  
Dark Field ◽  
Dark Field Microscopy

scholarly journals Intermittent swimming in live sea urchin sperm.

1980 ◽  
Vol 84 (1) ◽  
pp. 1-12 ◽  
Author(s):  
B H Gibbons
Keyword(s):  
Sea Urchin ◽  
Divalent Cations ◽  
Dark Field ◽  
Proximal Region ◽  
Ionophore A23187 ◽  
Quiescent State ◽  
Sodium Barbital ◽  
Dark Field Microscopy ◽  
Short Period ◽  
Live Sperm

Sperm of the sea urchin Tripneustes gratilla repeatedly start and stop swimming when suspended in seawater and observed by dark-field microscopy. While in the quiescent state, which usually lasts about a second, the sperm assume s shape resembling a cane, with a sharp bend of approximately 3.4 rad in the proximal region of the flagellum and very little curvature in the rest of the flagellum except for a slight curve near the tip. The occurrence of quiescence requires the presence of at least 2 mM Ca2+ in the seawater, and the percentage of sperm quiescent at any one time increases substantially when the sperm are illuminated with blue light. With intense illumination, close to 100% of the sperm become quiescent, and this percentage decreases gradually to approximately 0.3% over a 10(4)-fold decrease in light intensity. An increased concentration of K+ in the seawater also increases the percentage of quiescence, with a majority of the sperm being quiescent in seawater containing 80 mM KCl. The induction of quiescence by light or by increased KCl is completely inhibited by 10 micrometers chlorpromazine, and approximately 90% inhibited by 1 mM procaine or sodium barbital. Sperm treated with the divalent-cation ionophore A23187 swim quite normally, although for a relatively short period, in artificial seawater lacking divalent cations, but are abruptly arrested upon addition of 0.04--0.2 mM free Ca2%. The flagellar waveform of these arrested sperm is almost identical to that of light-induced quiescence in the live sperm. The results support the hypothesis that quiescence is induced by a rise in intracellular Ca2%, perhaps as a consequence of a membrane depolarization, and that it is similar to the arrest response in cilia.

Sliding velocity between outer doublet microtubules of sea-urchin sperm axonemes

1980 ◽  
Vol 44 (1) ◽  
pp. 169-186
Author(s):  
Y. Yano ◽  
T. Miki-Noumura
Keyword(s):  
Polyethylene Glycol ◽  
Atpase Activity ◽  
Sea Urchin ◽  
High Efficiency ◽  
Dark Field ◽  
Video Tape ◽  
Sliding Velocity ◽  
Atp Concentration ◽  
Close Relationship ◽  
Hemicentrotus Pulcherrimus

Using a dark-field microscope equipped with a high-efficiency TV camera including a video tape-recorder, we recorded the sliding movement between outer doublet microtubules of the demembranated axonemes of sea-urchin (Pseudocentrotus depressus and Hemicentrotus pulcherrimus) sperm flagella by adding ATP and trypsin at 25 degrees C. The time and length of the sliding doublet microtubules from axonemes were measured directly from the image on the picture monitor from the video tape. The sliding velocity was almost constant in the range from 0 to 2% polyethylene glycol concentration in the reactivation medium and decreased a little at more than 2%. We prepared various lengths of axoneme fragments by homogenizing whole axonemes and found that the shorter fragments showed similar sliding velocity to that of longer ones at less than 200 microM ATP, but slightly decreased speed at more than 500 microM. ATP. The sliding movement sometimes stopped and the percentage of sliding axonemes was lower below 2 micrograms/ml trypsin. Above 3 micrograms/ml, the process appeared to be more like disintegration than sliding movement, which may be due to excess digestion by trypsin. Sliding speed was therefore measured in a reactivation medium containing 2% polyethylene glycol with the addition of ATP and 2 micrograms/ml trypsin. The velocity increased in proportion to the increase in ATP concentration. Vmax was approximately 14 micrograms/s at 2 mM ATP. In order to compare the Km for the sliding velocity with that of the ATPase activity of the axonemes, we measured ATPase activity of axonemes prepared and assayed under conditions in which sliding movement in the axonemes could be induced. Neither the curve of ATPase activity nor the curve of sliding velocity plotted against ATP concentration obeyed Michaelis-Menten kinetics. The close relationship between ATPase activity and sliding velocity suggested that ‘sliding-movement-coupled ATPase activity’ may well be reflected in the axoneme ATPase reported here.

Elastic Scattering in Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 252-253
Author(s):  
J. Langmore ◽  
M. Isaacson ◽  
J. Wall ◽  
A. V. Crewe
Keyword(s):  
Electron Microscopy ◽  
Elastic Scattering ◽  
Cross Section ◽  
Quantum Noise ◽  
Dark Field ◽  
Elastic Cross Section ◽  
Biological Molecules ◽  
Dark Field Microscopy ◽  
Field Systems ◽  
Effects Of Radiation

High resolution dark field microscopy is becoming an important tool for the investigation of unstained and specifically stained biological molecules. Of primary consideration to the microscopist is the interpretation of image Intensities and the effects of radiation damage to the specimen. Ignoring inelastic scattering, the image intensity is directly related to the collected elastic scattering cross section, σɳ, which is the product of the total elastic cross section, σ and the eficiency of the microscope system at imaging these electrons, η. The number of potentially bond damaging events resulting from the beam exposure required to reduce the effect of quantum noise in the image to a given level is proportional to 1/η. We wish to compare η in three dark field systems.

Simulated Dark-Field Electron Micrographs of Point Defects and Organometallics

1975 ◽  
Vol 33 ◽  
pp. 200-201
Author(s):  
William Krakow
Keyword(s):  
Electron Micrographs ◽  
Point Defects ◽  
Structure Determination ◽  
Atomic Structure ◽  
Image Interpretation ◽  
Dark Field ◽  
Field Electron ◽  
Dark Field Microscopy ◽  
Dark Field Electron

Tilted beam dark-field microscopy has been applied to atomic structure determination in perfect crystals, several synthesized molecules with heavy atcm markers and in the study of displaced atoms in crystals. Interpretation of this information in terms of atom positions and atom correlations is not straightforward. Therefore, calculated dark-field images can be an invaluable aid in image interpretation.

Single molecule optical diffraction: A tool for understanding the structure of triple stranded left-hand helical cellulose

1989 ◽  
Vol 47 ◽  
pp. 1024-1025
Author(s):  
George C. Ruben ◽  
William Krakow
Keyword(s):  
Single Molecule ◽  
Helical Structure ◽  
Optical Diffraction ◽  
Maximum Diameter ◽  
Primary Cell Wall ◽  
Cellulose Synthesis ◽  
Left Hand ◽  
Left Handed ◽  
Freeze Dried ◽  
Diffraction Patterns

Tobacco primary cell wall and normal bacterial Acetobacter xylinum cellulose formation produced a 36.8±3Å triple-stranded left-hand helical microfibril in freeze-dried Pt-C replicas and in negatively stained preparations for TEM. As three submicrofibril strands exit the wall of Axylinum , they twist together to form a left-hand helical microfibril. This process is driven by the left-hand helical structure of the submicrofibril and by cellulose synthesis. That is, as the submicrofibril is elongating at the wall, it is also being left-hand twisted and twisted together with two other submicrofibrils. The submicrofibril appears to have the dimensions of a nine (l-4)-ß-D-glucan parallel chain crystalline unit whose long, 23Å, and short, 19Å, diagonals form major and minor left-handed axial surface ridges every 36Å.The computer generated optical diffraction of this model and its corresponding image have been compared. The submicrofibril model was used to construct a microfibril model. This model and corresponding microfibril images have also been optically diffracted and comparedIn this paper we compare two less complex microfibril models. The first model (Fig. 1a) is constructed with cylindrical submicrofibrils. The second model (Fig. 2a) is also constructed with three submicrofibrils but with a single 23 Å diagonal, projecting from a rounded cross section and left-hand helically twisted, with a 36Å repeat, similar to the original model (45°±10° crossover angle). The submicrofibrils cross the microfibril axis at roughly a 45°±10° angle, the same crossover angle observed in microflbril TEM images. These models were constructed so that the maximum diameter of the submicrofibrils was 23Å and the overall microfibril diameters were similar to Pt-C coated image diameters of ∼50Å and not the actual diameter of 36.5Å. The methods for computing optical diffraction patterns have been published before.

scholarly journals Multiplexed Plasmonic Nano-Labeling for Bioimaging of Cytological Stained Samples

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3509
Author(s):  
Paule Marcoux-Valiquette ◽  
Cécile Darviot ◽  
Lu Wang ◽  
Andrée-Anne Grosset ◽  
Morteza Hasanzadeh Kafshgari ◽  
...  
Keyword(s):  
Accurate Determination ◽  
Cell Types ◽  
Fine Needle Biopsy ◽  
Dark Field ◽  
Imaging Method ◽  
New Methods ◽  
Formalin Fixed Paraffin ◽  
Dark Field Microscopy ◽  
Formalin Fixed Paraffin Embedded

Reliable cytopathological diagnosis requires new methods and approaches for the rapid and accurate determination of all cell types. This is especially important when the number of cells is limited, such as in the cytological samples of fine-needle biopsy. Immunoplasmonic-multiplexed- labeling may be one of the emerging solutions to such problems. However, to be accepted and used by the practicing pathologists, new methods must be compatible and complementary with existing cytopathology approaches where counterstaining is central to the correct interpretation of immunolabeling. In addition, the optical detection and imaging setup for immunoplasmonic-multiplexed-labeling must be implemented on the same cytopathological microscope, not interfere with standard H&E imaging, and operate as a second easy-to-use imaging method. In this article, we present multiplex imaging of four types of nanoplasmonic markers on two types of H&E-stained cytological specimens (formalin-fixed paraffin embedded and non-embedded adherent cancer cells) using a specially designed adapter for SI dark-field microscopy. The obtained results confirm the effectiveness of the proposed optical method for quantitative and multiplex identification of various plasmonic NPs, and the possibility of using immunoplasmonic-multiplexed-labeling for cytopathological diagnostics.

scholarly journals Hyperspectral-enhanced dark field analysis of individual and collective photo-responsive gold–copper sulfide nanoparticles

Nanoscale ◽  
2021 ◽  
Author(s):  
Paula Zamora-Perez ◽  
Beatriz Pelaz ◽  
Dionysia Tsoutsi ◽  
Mahmoud G. Soliman ◽  
Wolfgang J. Parak ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Real Time ◽  
Copper Sulfide ◽  
Dark Field ◽  
Field Analysis ◽  
Dark Field Microscopy

Hyperspectral-enhanced dark field microscopy to correlate Au/CuS NPs’ changes in their physicochemical properties induced by cellular environments with their functionality as photothermal probes by tracking their scattering profile evolution in real time.

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