Cessation Of Rotation Research Articles

A Cell Migration Tracking Tool Supports Coupling of Tissue Rotation to Elongation

Cell migration is indispensable to morphogenesis and homeostasis. Live imaging allows mechanistic insights, but long-term observation can alter normal biology, and tools to track movements invivo without perturbation are lacking. We develop here a tool called M-TRAIL (matrix-labeling technique for real-time and inferred location), which reveals migration histories in fixed tissues. Using clones that overexpress GFP-tagged extracellular matrix (ECM) components, motility trajectories are mapped based on durable traces deposited onto basement membrane. We applied M-TRAIL to Drosophila follicle rotation, comparing invivo and exvivo migratory dynamics. The rate, trajectory, and cessation of rotation in wild-type (WT) follicles measured invivo and exvivo were identical, as was rotation failure in fat2 mutants. However, follicles carrying intracellularly truncated Fat2, previously reported to lack rotation exvivo, in fact rotate invivo at a reduced speed, thus revalidating the hypothesis that rotation is required for tissue elongation. The M-TRAIL approach could be applied to track and quantitate invivo cell motility in other tissues and organisms.

Muon spin spectroscopy of the rod-like liquid crystal 4-n-octyl-4'-cyanobiphenyl (8CB)

Avoided level crossing muon spin resonance (ALC-μSR) spectroscopy has been used to study the four cyclohexadienyl-type radicals produced by the addition of muonium (Mu) to the rod-like liquid crystal 4-n-octyl-4'-cyanobiphenyl (8CB). ALC-μSR spectra have been obtained over a wide temperature range in the isotropic (I), nematic (N), smectic-A (Sm-A) and crystalline (Cr) phases. The ALC-μSR spectra of the Mu adducts of 8CB are very similar to those of the Mu adducts of 4-n-pentyl-4'-cyanobiphenyl (5CB). Four Δ0 resonances were observed in the ALC-μSR spectra in the I, N and super-cooled Sm-A phases, from which the methylene proton hyperfine coupling constants (hfcs) of the Mu adducts of 8CB were determined as a function of temperature. The methylene proton hfcs of two of the radicals have unusual temperature dependence in the N and Sm-A phases and have smaller values than would be predicted from extrapolating the data in the isotropic phase. The shift of the hfcs is due to the dipolar hyperfine coupling, the ordering of the molecules along the applied magnetic field and the fluctuations of the molecules about the director. Δ1 resonances appear just below the Cr-Sm-A phase transition, which indicates that this transition is associated with cessation of rotation around the long molecular axes.

Gastric Arrhythmia and Nausea of Motion Sickness Induced in Healthy Japanese Subjects Viewing an Optokinetic Rotating Drum

The purpose of this study was to investigate whether nausea or gastric dysrhythmia, including tachygastria, which was determined by electrogastrography (EGG), were observed during optokinetic motion sickness in healthy Japanese volunteers. Twelve volunteers (9 men and 3 women) participated in the study. The subjects were asked to sit in a chair with their heads positioned in the center of a drum whose inside had been painted with black and white stripes. After a 15 min resting period, the drum was rotated at a speed of 60 degree/sec for 15 min. The EGG was continuously recorded for a total of 45 min (15 min resting period, 15 min rotation period, and 15 min recovery period). The severity of nausea was evaluated with a visual analogue scale (VAS) before, immediately after, and 15 min after the cessation of drum rotation. Other motion sickness symptoms were evaluated by scores of subjective symptoms of motion sickness (SSMS). Of 12 subjects who completed the study, 10 complained of nausea immediately after cessation of drum rotation. The VAS score for nausea immediately after the drum rotation period and 15 min after cessation of the rotation was significantly higher than during the resting period. The EGG during the drum rotation period showed a decrease in normogastria, which was accompanied with an increase in tachygastria. We conclude that gastric tachyarrhythmia and nausea may be induced by viewing an optokinetic rotating drum in healthy Japanese subjects who may have a hypersusceptibility to vection-induced motion sickness. The gastric dysrhythmia obtained with EGG could be a useful observation to support the appearance of nausea induced by optokinetic motion sickness.

Effect of aging on the otolith-ocular reflex

We assessed the influence of age on the otolith-ocular reflex and semicircular canal-otolith interaction. Healthy young (n=30) and healthy older (n=60) subjects were rotated about an earth vertical axis, and about a 30 degree off-vertical axis. Eye movements during and following rotation were recorded using electro-oculography. Results indicated that there were statistically significant changes in the otolith-ocular reflex and semicircular canal-otolith interaction as a function of age. The modulation component during off-vertical axis rotation (OVAR) was greater in the older group compard to the young adults, whereas the bias component was smaller with advanced age. The foreshortening of the vestibulo-ocular reflex time constant induced by post-rotatory head tilt following cessation of rotation was less prominent in the older group. There were no consistent changes in the semicircular canal-ocular reflex. Overall, response parameters showed more variability in the older subjects. We conclude that age related changes in the otolith-ocular reflex and semicircular canal-otolith interaction are a result primarily of a degradation of central vestibular processing of otolith signals rather than a decline of peripheral vestibular function.

William Charles Wells (1757–1817) and vestibular research before Purkinje and Flourens

Vestibular research before Flourens typically involved vertigo and eye movements. In 1820 Purkinje integrated these in studies of postrotary vertigo and he is linked with Flourens as a founder of vestibular research. In the late eighteenth century Erasmus Darwin described vertigo in detail, but he did not accept that it involved an oculomotor component. Darwin reached this conclusion despite detailed experiments by William Charles Wells (1757-1817), who described the pattern of postrotary nystagmus and its dependence on head orientation during rotation. Wells generated afterimages prior to rotation and subsequently compared their motions with those of real images. He was able to distinguish between the slow and fast phases of nystagmus, its reducing amplitude following cessation of rotation, its suppression with fixation, and its torsional dimension. In many ways, Wells's experiments were more sophisticated than those of Purkinje, and he should be recognised as a founder of vestibular research. Possible reasons for the neglect of Wells's work are discussed.

Peering over the Sun's pole: behavior of its rotational vortex

A new method for measuring spectroscopically the rotation at the Sun's poles is described. Using solar CO lines at 4.666 µm, infrared spectra are recorded at a fixed limb distance of 4.8 arc sec while progressing along an arc ±5.7 deg from the Sun's rotational pole. Since the poles dip twice a year to about 7 arc sec from the limb, our observations can range either side of and through the vortex axis. Advantages to this technique are: (1) a low disturbing signal from supergranules owing to their superposition at the limb, (2) no ‘limb shift’ error since limb distance is constant and the CO lines have no known limb shift, (3) emphasis is on the quiet Sun since the CO molecule is confined there, (4) negligible scattered light in the IR (<1%), and (5) the improved seeing afforded by the IR. Although any definitive determination of solar rotation requires observations over an extended time span, our preliminary results suggest two features peculiar to the extreme pole: (1) the occasional apparent cessation of rotation, (2) some sort of singularity, again occasional, producing a sharp velocity signal (a vortex?) within 1 deg of the pole.

Kinetic studies of temperature-induced helix hand inversion in Bacillus subtilis macrofibers.

The inversion of Bacillus subtilis macrofibers from right to left handedness induced by a temperature upshift was compared with inversion from left to right handedness induced by a temperature downshift. Following an upshift the new steady-state growth rate was achieved prior to inversion of helix orientation. There was no discernible perturbation of growth rate at the time of inversion. The time required after a temperature shift up or down for fiber rotation in the original sense to cease was dependent on the temperature to which the fibers were transferred and was always shortest when this temperature was highest. The results suggest a basic asymmetry in the two inversion processes. Cessation of rotation in the right-to-left inversion appeared to reflect contributions of the old and new wall materials that depended on their twist values, whereas the left-to-right inversion appeared to require that a specific amount of newly made wall material be inserted into the cell surface. The degree of twist of the newly inserted right-handed material appeared not to influence the timing of inversion.

An Alternative Test of the Adams-Creamer Decay Hypothesis in Timing Motor Responses

Ss were randomly assigned to either a vestibular proprioception (VP) group (N = 30) or a no vestibular proprioception (NVP) group (N = 30). The VP group was tested while supine on a table rotated 60 deg. in the vertical plane and, at the cessation of rotation, Ss estimated a 2-sec. interval. Procedures were identical for the NVP group with the exception that they received no body rotation. All Ss received 40 trials and knowledge of results was given during a 20-sec. intertrial interval. The VP group had significantly smaller mean absolute and algebraic error scores than the NVP group. The difference between the mean variable error scores of the two groups was not significant. Results supported the Adams-Creamer decay hypothesis in terms of absolute error scores and algebraic error scores, but did not support the hypothesis in terms of variable error scores.

Cortical Responses to RotationI. Responses Recorded after Cessation of Rotation

Averaged cortical responses to labyrinthine stimulation induced by sudden cessation of single rotations were studied using a Mnemotron Computer of Average Transients. Following rotation there appeared in cats with the eyelids closed diffuse, slow, sometimes multiphasic responses. They were probably due to excitation of the diffuse thalamic system. In human subjects similar responses could be obtained either diffusely or prevalent or exclusively from the preoccipital and/or parastriate area. The responses observed in posterior parts of the cerebral hemisphere following cessation of rotation appeared also, if the animals were flaxedilized, or the second somatic sensory area was ablated in both hemispheres. Bilateral labyrinthectomy abolished these responses. While the observation of the ocular reactions to labyrinthine stimulation permits one to ascertain the excitability of the vestibulo-ocular reflex arc only, the recording of the cortical responses to rotation may perhaps be developed into a clinical too...