Type Of Spindle Research Articles

Loss of kinesin-8 improves the robustness of the self-assembled spindle in Schizosaccharomyces pombe.

ABSTRACTChromosome segregation in female meiosis in many metazoans is mediated by acentrosomal spindles, the existence of which implies that microtubule spindles self-assemble without the participation of the centrosomes. Although it is thought that acentrosomal meiosis is not conserved in fungi, we recently reported the formation of self-assembled microtubule arrays, which were able to segregate chromosomes, in fission yeast mutants, in which the contribution of the spindle pole body (SPB; the centrosome equivalent in yeast) was specifically blocked during meiosis. Here, we demonstrate that this unexpected microtubule formation represents a bona fide type of acentrosomal spindle. Moreover, a comparative analysis of these self-assembled spindles and the canonical SPB-dependent spindle reveals similarities and differences; for example, both spindles have a similar polarity, but the location of the γ-tubulin complex differs. We also show that the robustness of self-assembled spindles can be reinforced by eliminating kinesin-8 family members, whereas kinesin-8 mutants have an adverse impact on SPB-dependent spindles. Hence, we consider that reinforced self-assembled spindles in yeast will help to clarify the molecular mechanisms behind acentrosomal meiosis, a crucial step towards better understanding gametogenesis.

Продуктивність й економічна оцінка насаджень яблуні на підщепі М.9 залежно від способу і строку обрізування крони

Продуктивність й економічна оцінка насаджень яблуні на підщепі М.9 залежно від способу і строку обрізування крони

Productivity formation features of Apple trees (<i>Malus domestica</i> Borkh.) with intermediate insertion of low-growth rootstock EM-IX in the Crime

The long-term results of studies on the formation of productivity in apple trees on the medium-sized rootstock MM-106 with an intermediate insert of a low-growth rootstock EM - IX are given. The objects of research are cultivars: Golden Delicious, Jonagold, Kimmeriya, Krymskoe with a planting pattern of 3.5 x 1.25 m and 3.5 x 1.75 m. Trees are formed according to the type of free spindle. As a result of the research, a high potential application of the combined stock (with intercalary insert) in the garden, which provides early fruiting, a rapid increase in yield, high marketability and keeping quality of fruits, is revealed. Domestic intensive gardens on a combined stock can be created in the conditions of the Crimea without any support, which saves material resources for their laying. The formation of trees according to the type of free spindle in the gardens makes it possible to compact the planting of trees in a row by 20-25% and reduce the amount of labor expended on pruning trees and harvesting 1.6 times, depending on the cultivar. Realization of the productivity potential in such gardens is determined by the high level of agricultural technology with the obligatory implementation of technological methods.

Reliability modeling and analysis of heavy-duty CNC machine tool spindle under hybrid uncertainty

Heavy-duty CNC machine tools have been used to process and manufacture the products and the key components with concerns the national economy and defense security, and the quantity of heavy-duty CNC machine tools measures the industrialization level and the comprehensive strength of a country. Compared with the general machine tools, heavy-duty CNC machine tools have a more complex system structure, smaller size sample, less experimental data, incomplete information, more complex failure mechanism and other characteristics. The heavy-duty CNC machine tools as well as its sub-systems are often influenced by hybrid uncertainty and the correlated failures of different components. Therefore, the existing reliability technologies cannot be applied directly, thus new reliability technologies for specific to heavy-duty CNC machine tools are needed. Aiming at the problems analyzed above, this paper focus on the reliability modeling and analysis of heavy-duty CNC machine tool spindle under hybrid uncertainty. Firstly, this paper analyzed various uncertainty factors influencing the reliability of the heavy-duty CNC machine tool spindle and the limitations of the existing uncertainty quantification methods, constructed a unified framework for hybrid uncertainty quantification based on the imprecise probability theory. Secondly, based on the uncertainty quantification framework and stress-strength interference theory, this paper proposed an imprecise structural reliability analysis and modeling method for mechanical components. Finally, the models proposed in this paper were verified through the imprecise structural reliability analysis of a certain type of milling spindle, the imprecise structural reliability models under different failure modes are proposed. And the results are compared with the results calculated by Monte Carlo method. It has shown that the proposed method has a higher computational efficiency.

Structure design and thermal analysis of a new type of friction stir weld spindle

This article aims to present a new type of friction stir weld spindle system with 2 degrees of freedom. It explains the thermal–mechanical coupling mechanism between the welding tool and the workpi...

Topographical distribution of fast and slow sleep spindles in medicated depressive patients.

To compare the properties of sleep spindles between healthy subjects and medicated patients with major depressive episode, including frequency range, spectra power, and spatial distribution of spindle power. Continuous 16-channel EEG was used to record nocturnal sleep in healthy control subjects and medicated depressive patients. Recordings were analyzed for changes in EEG power spectra and power topography. Additionally, we graphically demonstrated the pattern of spatial distribution of each type of sleep spindle, divided into fast (12.5-14 Hz) and slow spindles (11-12.5 Hz). Sleep EEG records of depressive subjects exhibited a significantly higher amplitude of slow spindles in the prefrontal region, compared with the healthy controls (P < 0.01). Fast spindles were dominant in the centroparietal region in both depressive patients and the control group. Enhanced slow spindles in the prefrontal region were observed in the medicated depressive patients and not in the healthy controls. The frequency of fast spindles in depressive patients was globally higher than that in healthy participants. The alteration in sleep spindles seen in medicated depressive subjects may reflect a pharmacological modulation of synaptic function involving the thalamic-reticular and thalamocortical mechanisms.

Mixed epithelial and stromal tumor of the kidney

Mixed epithelial and stromal tumor (MEST) of the renal pelvis or the older terminology cystic hamartoma of renal pelvis is a rare benign tumor and recently been recognized as a distinct clinical and pathological entity. These complex neoplasms are composed of a mixture of stromal and epithelial elements and are seen predominantly in women (ratio of women to men 6:1) and are generally seen in perimenopausal women with presenting symptoms of flank pain, hematuria or symptoms of urinary tract infection. We present here a case of MEST in a 48-year-old female who presented with a mass per abdomen associated with a mild dragging pain of 6 months duration. The ultrasonography report was of a multi-cystic lesion in the right kidney. Surgical excision of the lesion showed a mass measuring 18 × 14.5 × 7 cm with attached normal ureter. The outer surface was bosselated and showed multiple-cystic nodules with pale brown to dark brown smooth and glistening surface. The tumor was well circumscribed and there were multiple cysts of varying sizes separated by stroma arising from the dilated pelvicalyceal system. The wall of the cysts are covered by papillary excrescences. On histological examination, a well delineated tumor composed of cysts of varying sizes lined by columnar, cuboidal and transitional epithelium. Surrounding stroma showed a mixture of ovarian type of stroma and spindle shaped cells of smooth muscle type having plump nuclei. Sections from the renal-tissue adjacent to the tumor showed normal glomeruli and tubules.

Donut Stones as Thigh-Supported Spindle Whorls: Evidence of Ancient Maya Household Yarn and Cordage Production

AbstractDonut stones are a relatively common class of ground stone artifact found at archaeological sites throughout Mesoamerica and Andean South America, and a variety of functional interpretations have been proposed for these artifacts. In this article, ethnographic, ethnohistoric, and archaeological data are presented along with the results of replicative experiments in support of an argument that some donut stones from the Maya Highlands and Southern Lowlands may have functioned as whorls for a previously unrecognized type of thigh-supported spindle. Based on a functional interpretation of donut stones as thigh-supported spindle whorls, these artifacts can potentially be used to provide insight into the nature of ancient Maya household yarn and cordage production.

Optimal contact design and allowable limit on spindle assembly of aluminum hot rolling process

Aluminum sheet ingots go through the hot rolling process to be converted into coils with a gauge suitable for the cold rolling process or plates. The top spindle, end coupling and slipper metal are main components of the hot roll process and used for transmission of rotational power with heavy-duty load. The top spindle connected to the motor and end coupling connected to the roller are combined with the slipper metal which acts as a bearing and joint. The contact surface between end coupling and slipper metal is subjected to stress concentration, and life cycles of slipper metal is reduced. This study aims to minimize the mechanical problems which might happen in the production process. The load condition for hot rolling processes is derived under load condition that is conducted for a hot rolling process under slipper metal combination types and operation situations. A structural analysis is performed by applying mechanical characteristics, combination type, and rotational boundary condition of top spindle, end coupling and slipper metal. Optimal design is performed for contact surface between end coupling and slipper metal. Interference analysis is studied to reduce the stress concentrations. Kinematics simulation is performed by applying the various combination type and dynamic boundary condition of the mill spindle assembly. The interference does not occur on the top spindle and slipper metal, so actual driving of the hot mill spindle assembly can operate in the normal operation condition.

Drosophila dd4mutants reveal that γTuRC is required to maintain juxtaposed half spindles in spermatocytes

The weak spindle integrity checkpoint in Drosophila spermatocytes has revealed a novel function of the gamma-tubulin ring complex (gammaTuRC) in maintaining spindle bipolarity throughout meiosis. Bipolar and bi-astral spindles could form in Drosophila mutants for dd4, the gene encoding the 91 kDa subunit of gammaTuRC. However, these spindles collapsed around metaphase and began to elongate as if attempting anaphase B. The microtubules of the collapsing spindle folded back on themselves, their putative plus ends forming the focused apexes of biconical figures. Cells with such spindles were unable to undergo cytokinesis. A second type of spindle, monopolar hemi-spindles, also formed as a result of either spindle collapse at an earlier stage or failure of centrosome separation. Multiple centrosome-like bodies at the foci of hemi-spindles nucleated robust asters of microtubules in the absence of detectable gamma-tubulin. Time-lapse imaging revealed these to be intermediates that developed into cones, structures that also had putative plus ends of microtubules focused at their tips. Unlike biconical figures, however, cones seemed to contain a central spindle-like structure at their apexes and undergo cytokinesis. We conclude that spermatocytes do not need astral microtubules nucleated by opposite poles to intersect in order to form a central spindle and a cleavage furrow.

Restoration of involuntary tonic contraction of the levator muscle in patients with aponeurotic blepharoptosis or Horner syndrome by aponeurotic advancement using the orbital septum.

Müller's muscle can be thought of as a large serial type of muscle spindle of the levator muscle. Effective stretching of the mechanoreceptor in the proximal part of Müller's muscle by voluntary phasic contraction of the levator muscle for initial opening of the eye induces involuntary tonic contraction of the levator muscle as a stretch reflex via the mesencephalic trigeminal nucleus, to maintain an adequate visual field. After disinsertion of the levator aponeurosis from the tarsus by habitual rubbing, elongation of Müller's muscle secondary to thinning (aponeurotic blepharoptosis) or paralysis (Horner syndrome) desensitises the mechanoreceptor of Müller's muscle, resulting in blepharoptosis. Shortening of the elongated and thinned Müller's muscle by instillation of phenylephrine, and surgical shortening, and fixation of the disinserted, elongated, and thinned aponeurosis using the orbital septum, restored involuntary tonic contraction of the levator muscle in nearly all of 2000 patients with aponeurotic blepharoptosis and in 11 patients with Horner syndrome.

Variations of instability in a rotating spindle system with various bearings

To drive the speed of spindle faster and faster, especially for micro-via-drilling, the gas bearing–spindle is a must. However, most investigations of the dynamic characteristics of the spindle system are limited to the ball bearing type of spindle. This work examines the dynamic instability of a rotating spindle system with various bearings to elucidate the difference between the ball and gas bearing–spindle systems. A round Euler–Bernoulli beam is used to approximate the spindle. The Hamilton principle is applied to derive the equation of motion for the spindle system, and the multiple scales perturbation method is employed to solve the instability solution of the system. The effects of bearing types and speeds of rotation on the dynamic characteristics and instability of a rotating spindle system are further studied.

A Decision-Making Methodology for Basic Layout Design of Machine Tools.

In the design procedure, designers always analyse and consider various requirements and also conduct necessary information processing so as to obtain the most suitable result. In order to rationally automatise such a design procedure, it is necessary to process the design and its related information effectively by a computer system, especially from the aspect of decision making while processing the information. Thus, in this paper, a decision-making methodology for the basic layout design of machine tools has been proposed to establish an intelligent CAD system. The proposed methodology is based on the priority rule of the input specification, and its validity has also been verified through some case studies on the selection of the suitable bearing type and arrangement of the main spindle in machine tools by the usage of a developed system for supporting decision making.

Sleep spindles revisited.

A few additional points about sleep spindles are made in this complementary article to the excellent manuscript on spindles by Jankel and Niedermeyer. One of these is to discuss the improbability of a necessary close relationship between any two patterns just simply because they represent fast activity, waxing and waning in amplitude, therefore showing some morphological similarity to the sleep spindle. In this context, one example may be the delta brushes of the premature infant. One fascinating type of sleep spindle appears at approximately 3 to 5 months of age, the very long-lasting form that is usually less monophasic than the type that develops in the second half of the first year of life. The monophasic form often is asynchronous between the two sides during the first year and occasionally may appear in this form from 1 to 2 years of age, but such asynchrony should not appear in the normal 2 year old. Caution is urged in calling those records without any spindles abnormal, except when the interpreter can be certain that the "spindle stage" was actually achieved. Also, the normal 20-28/s rhythms of the drowsy child under 6 years of age should not be confused with the effect of medication, especially chloral hydrate, which likely has little or no fast activity associated with it. Relevant infrahuman data have revealed that adult monkeys do not usually show sleep spindles but show the closely related vertex sharp transients maximal on the cingulate area inferior to the supplementary motor region.(ABSTRACT TRUNCATED AT 250 WORDS)

ヒト内こう頭筋特にひ裂筋における筋紡錘の形態学的研究

The existence of the muscle spindles in the arytenoid muscle of the human larynx was confirmed. The morphological features were described in detail using light- and electron-microscopes. The specimens were obtained from three larynges. The seven muscle spindles were found in all of the three specimens. The diameter at the equator was 85 to 115μm., and the number of the intrafusal muscle fibers was two to five. The two types of the intrafusal muscle fibers were differentiated, the nuclear bag type and nuclear chain type. As the specific type of the muscle spindle, the monofibrillar type and compound type were also found. The dimension of the muscle spindle in the arytenoid muscle was relatively small in comparison with that in other skeletal muscle.

Zur Bestimmung der Scherbeständigkeit von Stärkekleistern

AbstractOn Determination of Shearing Stability of Starch Pastes. Test conditions for the shearing stability test of starch pastes are not sufficiently outlined in existing publications. In the present paper, first of all a determination of optimum parameters (type of paste production, type of stirrer, stirring time, stirrer revolutions, viscosity measurement etc.) for a shearing stability test was attempted. It became apparent that shearing treatment of 5 min by means of a blade stirrer at a number of stirrer revolutions of 1800 r.p.m. with a 5% paste concentration is sufficient to determine shearing stability of a starch paste.For viscosity measurement which as well as pasting and shearing stress is carried out a 95 °C, a Brookfield viscosimeter is used. Provided measuring conditions (type of spindle, spindle revolutions) are kept constant before and after shearing stress, shearing stability can be expressed as remaining viscosity as a percentage of the initial viscosity.Furthermore, reproducibility of paste production as well as that of the whole shearing stability test were determined. Finally, a test was carried out as to wether there is a connection between shearing and heat stability of paste. Values obtained from 11 commercial products made such a connection between the two criteria apparent.

The response of chelonian muscle spindles to mechanical stimulation

Single unit recordings have been made from the muscle spindles of the extensor digitorum brevis I muscle of the chelonian emys orbicularis. The responses to ramp-type mechanical stretches (up to 5 mm s −1 velocity and up to 1.6 mm extension) were compared to those of spindles from other groups. It is found that the spindles have lower rates of firing than those from the other groups with the exception of the snake spindles. Generally the spindles behaved like the secondary ending of mammalian spindles or the tonic type of snake spindle in terms of their response to the velocity of stretch. The results are consistent with the view that the tonic response arises from intrafusal muscle fibres in which the sensory region has a structure which is fairly uniform and similar to that of the polar regions and not interrupted by accumulations of nuclei.

A study of single and tandem types of muscle-spindle in the cat.

A tandem spindle is defined a one in which several encapsulated sensory regions are linked together by some degree of muscle fibre continuity. Generally only one or two muscle fibres are continuous from capsule to capsule, while the rest taper off and partake of only one encapsulation. In the most common type, two capsules occur in linear succession (double tandem); triple and quintuple arrangements were also observed but not quadruple ones. Of 64 complete tandem spindles from cat rectus femoris cut in transverse section, 88% were double, 9% triple, and 3% quintuple. As measured in sectioned adult rectus femoris, the length of tandem spindles was 8.43 to 22.30 mm, (S. D.); by contrast, the length of 144 single spindles was 2.40 to 13.68 mm, mean 7.02 ± 2.45 mm (S. D). A study of the afferent innervation of 27 tandem spindles from the mesial flexor digitorum longus, semitendinosus, soleus, and rectus femoris muscles showed that the typical pattern was for a complex or intermediate capsule to be linked with one or two simple capsules. A quarter of the double tandems had complex or intermediate/intermediate capsule combinations; combinations in which all the capsules were simple, or all complex, did not occur. The primary ending in the simple capsules is invariably either holly or predominantly irregular, and the intramuscular diameter o f the fibre supplying it is usually less than that of fibres supplying other primary endings. On the basis of a study of serial transverse sections of a pair of kitten recti, and of twelve blocks sampled from the recti of six cats, it is concluded that 16 to 20% of the spindles in the cat’s rectus femoris are of the tandem type. Access to quantitative data gathered in connexion with other work suggests that, as compared with rectus femoris, the proportion of tandem spindles in semitendinosus and mesial flexor digitorum longus is slightly higher; in soleus, about the same; and in the pes interossei, considerably lower. An analysis of the results of teasing seven entire adult rectus femoris muscles indicates the following conclusions with regard to the proprioceptive equipment: ( a ) the intermediate type of single spindle occurs, on the average, with about double the frequency of either simple or complex types; ( b ) primary and secondary endings are present in about equal proportion in the muscle; ( c ) there are usually fewer tendon-organ endings than primary endings (average 80% ), but the proportion varies widely (41 to 139%) in different muscles; ( d ) paciniform corpuscles are relatively scarce and there appears to be no correlation between their frequency of occurrence as compared with other proprioceptors. The soleus, semitendinosus, and mesial flexor digitorum longus muscles appear to resemble rectus femoris with respect to ( a ) and ( b ), but in the fourth internal intercostal muscle complex spindles appear to be most frequent and secondary endings more abundant. The position and measurements of 144 single spindles in rectus femoris indicate that the lengths of the poles are related to the position of the spindle in the extrafusal muscle bundles and its orientation with respect to nerve supply. A re-appraisal of Ruffini’s classic paper (1898) on muscle-spindles suggests that in several respects the description was based on incomplete spindles cut in teasing gold chloride preparations. It is also evident that, owing to the methods employed, counts of muscle spindles made by most previous workers should probably be regarded as counts of spindle capsules. Failure to distinguish between single and tandem types of spindle also vitiates many of the measurements made of spindle length. Some discussion is offered on whether there is any functional significance in the tandem type of spindle and the proportional distribution of spindle types in a muscle.