scholarly journals The kinetic polarities of spindle microtubules in vivo, in crane-fly spermatocytes. II. Kinetochore microtubules in non-treated spindles

1985 ◽  
Vol 79 (1) ◽  
pp. 39-65 ◽  
Author(s):  
B.B. Czaban ◽  
A. Forer
Keyword(s):  
Ultraviolet Light ◽  
The Other ◽  
Spindle Fibre ◽  
Near Ultraviolet ◽  
Other Hand ◽  
Spindle Microtubules ◽  
Spindle Fibres

We determined the kinetic polarities of chromosomal spindle fibre microtubules in vivo: either the kinetochore or pole ends of chromosomal spindle fibres were irradiated with near-ultraviolet light to prevent depolymerization by colcemid. Irradiations began either just before or just after colcemid addition; cells were continually irradiated and continuously immersed in colcemid. Irradiations of kinetochore ends of chromosomal spindle fibres prevented depolymerization; irradiations of pole ends did not. Therefore, since colcemid acts by binding to the ‘on’ (assembly) ends of microtubules, the on ends of chromosomal spindle fibre microtubules are at the kinetochores. That is, in untreated chromosomal spindle fibres in vivo tubulin monomers add to kinetochore microtubules at the kinetochore ends. Tubulin diffused from the irradiation sites: irradiations of the cytoplasm sometimes prevented depolymerization of chromosomal spindle fibres. Prevention of chromosomal spindle fibre depolymerization was dependent on the distance of the irradiated region from the nearest chromosome; the longer the distance the less likely was it that the irradiation prevented depolymerization. On the other hand, prevention of chromosomal spindle fibre depolymerization was not dependent on the distance from the irradiated spot to the nearer pole. This analysis, too, we argue, strongly suggests that the kinetochore ends of the chromosomal spindle fibres are the on ends.

Analysis of chromosome movement in crane fly spermatocytes by ultraviolet microbeam irradiation of individual chromosomal spindle fibres. I. General results

1981 ◽  
Vol 59 (9) ◽  
pp. 770-776 ◽  
Author(s):  
Peggy J. Sillers ◽  
Arthur Forer
Keyword(s):  
Ultraviolet Light ◽  
Monochromatic Light ◽  
The Other ◽  
Spindle Fibre ◽  
Chromosome Movement ◽  
Opposite Pole ◽  
Other Hand ◽  
Ultraviolet Microbeam ◽  
The Difference ◽  
Spindle Fibres

Single chromosomal spindle fibres in anaphase Nephrotoma ferruginea (crane fly) spermatocytes were irradiated with monochromatic ultraviolet light focussed to a 4-μm spot by means of an ultraviolet microbeam apparatus. The movement of the half-bivalent associated with the irradiated spindle fibre was either unaffected or the half-bivalent stopped moving; i.e., the effect was all-or-none. When the half-bivalent associated with the irradiated spindle fibre did stop moving, the partner half-bivalent moving towards the opposite pole (i.e., the half-bivalent with which the first half-bivalent was previously paired) also stopped moving: all other half-bivalents moved normally. In over 90% of the 69 cases the movements of the two half-bivalents were only temporarily blocked; when movement resumed both half-bivalents resumed movement at the same time, after stoppage times ranging from 2 min to more than 15 min. In a few cases the half-bivalents never resumed poleward motion.When half-bivalents that had stopped movement finally resumed movement they often did not reach the poles; i.e., they "lagged" and remained separate from the other chromosomes. This result occurred only in spermatocytes of N. ferruginea. In spermatocytes of N. suturalis or N. abbreviata, on the other hand, the stopped half-bivalents did not lag but always reached the poles.Half-bivalent pairs that stopped moving in N. ferruginea spermatocytes did so for shorter times than did those previously reported (after irradiation of chromosomal spindle fibres) in N. suturalis spermatocytes. We suggest that the difference is due to our use of monochromatic ultraviolet light as opposed to the previous use of heterochromatic ultraviolet light. We assume that different wavelengths of monochromatic light produce different effects, that any given monochromatic irradiation produces only one effect (albeit different effects at different wavelengths), but that heterochromatic irradiations can produce multiple effects.Irradiation of the interzone (between separating half-bivalents) had no effect on the chromosome-to-pole movements of the half-bivalents. Therefore the stoppage of movement of half-bivalent pairs is specific for irradiation of chromosomal spindle fibres. On the other hand, irradiation of the interzone often blocked pole-to-pole elongation.

scholarly journals The kinetic polarities of spindle microtubules in vivo, in crane-fly spermatocytes. I. Kinetochore microtubules that re-form after treatment with colcemid

1985 ◽  
Vol 79 (1) ◽  
pp. 1-37 ◽  
Author(s):  
B.B. Czaban ◽  
A. Forer
Keyword(s):  
Ultraviolet Light ◽  
Near Ultraviolet ◽  
Spindle Microtubules ◽  
Spindle Fibres ◽  
Lines Of Evidence

In newly formed chromosomal spindle fibres we determined the kinetic polarities of the microtubules, that is, the ends to which tubulin monomers add. Spindles disappeared after cells were continuously immersed in colcemid; then portions of the cells were continuously irradiated with a microbeam of near-ultraviolet light to reverse locally the effect of the colcemid. From the following lines of evidence we conclude: that microtubules are organized by the chromosomes; and that tubulin monomers add to the chromosomal spindle fibres at the kinetochore. When chromosomes were irradiated chromosomal spindle fibres grew in different directions, not necessarily focussed to a common pole; this would not occur if the chromosomal spindle fibres were organized by poles. Chromosomal spindle fibres were sometimes associated with only some of the chromosomes; this would not occur if the fibres were organized by the poles. Thus, chromosomal spindle fibres are organized solely by chromosomes; these spindle fibres are functional since the associated chromosomes moved in anaphase. When chromosomes were irradiated the re-formed spindle fibres grew up to 10 microns past the edges of the irradiating spot. Experimentally, free tubulin did not diffuse more than 4–5 microns from the irradiated spot. Thus we conclude that the tubulin monomers add at the kinetochores and not at the distal ends of the fibres.

Ultraviolet microbeam irradiation of chromosomal spindle fibres shears microtubules and permits study of the new free ends in vivo

1988 ◽  
Vol 91 (4) ◽  
pp. 455-468 ◽  
Author(s):  
P.J. Wilson ◽  
A. Forer
Keyword(s):  
Ultraviolet Light ◽  
Relative Stability ◽  
Dynamic Instability ◽  
Spindle Fibre ◽  
Microtubule Depolymerization ◽  
Immunofluorescence Analysis ◽  
Ultraviolet Microbeam ◽  
Spindle Fibres

Irradiation of birefringent chromosomal spindle fibres in crane-fly spermatocytes in metaphase I or anaphase I produces an area of reduced birefringence (ARB) on the fibre. This ARB moves poleward and is lost at the pole. Ultrastructural and immunofluorescence analysis of ARBs obtained by irradiation with monochromatic ultraviolet light of wavelength 260 nm shows that the microtubules in the irradiated area are depolymerized, though the rest of the spindle appears unaffected. The area of microtubule depolymerization moves poleward with the ARB, and once the ARB reaches the pole the irradiated half-spindle appears normal. The motion of the ARB, therefore, appears to be due to the behaviour of the sheared microtubules in the chromosomal spindle fibre. The relative stability of the sheared microtubules shows that chromosomal fibre microtubules are not dynamically unstable, as are microtubules under certain conditions in vitro. However, ARB motion may be due to a moderated version of dynamic instability. Possible models for ARB motion are discussed.

Action spectrum for changes in spindle fibre birefringence after ultraviolet microbeam irradiations of single chromosomal spindle fibres in crane-fly spermatocytes

1983 ◽  
Vol 62 (1) ◽  
pp. 1-25
Author(s):  
P.J. Sillers ◽  
A. Forer
Keyword(s):  
Ultraviolet Light ◽  
Action Spectrum ◽  
The Other ◽  
Spindle Fibre ◽  
Chromosome Movement ◽  
Ultraviolet Microbeam ◽  
Two Peaks ◽  
Wavelength Light ◽  
Spindle Fibres ◽  
In Cells

Single chromosomal spindle fibres in Nephrotoma suturalis (crane-fly) spermatocytes in metaphase and anaphase were irradiated with monochromatic ultraviolet light focussed to a 2 micrometer spot. In cells in both metaphase and anaphase either the birefringence of the irradiated spindle fibre was altered in the irradiated region, or there was no change, depending on the dose and wavelength of ultraviolet light used for the irradiation. When there was an area of reduced birefringence (ARB), it moved poleward regardless of whether the associated chromosome moved poleward. When cells were irradiated in early metaphase they remained in metaphase until the ARB reached the pole. In some cells irradiated in late metaphase the chromosomes began anaphase before the ARB reached the pole; in many such cells anaphase was abnormal in that all six half-bivalents separated at the start of anaphase but none moved polewards. In all cases the ARB moved poleward at the same speed as subsequent chromosome movement; that is, at about 0.8 micrometer/min. In cells irradiated in anaphase, spindle fibre birefringence was reduced independently of blockage of chromosome movement. Because birefringence and movement were altered independently there were four classes of results: (1) in some cases there was no effect on the movement of the chromosome associated with the irradiated spindle fibre and no effect on the birefringence of the irradiated spindle fibre. (2)In some cases, primarily with 260 nm wavelength light, there was no effect on the movement of the chromosome associated with the irradiated spindle fibre and there was an effect on the birefringence of the irradiated spindle fibre. (3) In some cases, primarily with 290 nm wavelength light, there was an effect on the movement of the chromosome associated with the irradiated spindle fibre and no effect on the birefringence of the irradiated spindle fibre. (4) In some cases, primarily with 270 nm and 280 nm wavelength light, there was an effect on the movement of the chromosomes associated with the irradiated spindle fibre and there was an effect on the birefringence of the irradiated spindle fibre. The action spectrum for reducing spindle fibre birefringence in crane-fly spermatocytes had two peaks, one at 260 nm and the other, less sensitive, at 280 nm. For irradiations at 270 nm, 280 nm and 290 nm, five to fifty times more energy was needed to reduce spindle fibre birefringence than to stop chromosome movement, but for irradiations at 260 nm five times less energy was needed to reduce spindle fibre birefringence than to stop chromosome movement. The action spectrum for reducing spindle fibre birefringence is quite different from that for stopping chromosome movement.

The behaviour of microtubules in chromosomal spindle fibres irradiated singly or doubly with ultraviolet light

1989 ◽  
Vol 94 (4) ◽  
pp. 625-634
Author(s):  
P. Wilson ◽  
A. Forer
Keyword(s):  
Ultraviolet Light ◽  
Single Fibre ◽  
The Other ◽  
Microbeam Irradiation ◽  
Other Hand ◽  
Ultraviolet Microbeam ◽  
Spindle Fibres

Areas of reduced birefringence (ARBs) produced by ultraviolet microbeam irradiation are areas of depolymerized microtubules. ARBs probably move poleward either by microtubule subunit addition at the kinetochore and loss at the pole, or by microtubule subunit addition at one edge of the ARB and loss from the other edge. In this paper we have used two approaches to try to distinguish between these two models. First, we determined whether the edges of the ARB move at the same rate; if ARB motion is due solely to addition at the kinetochore and loss at the pole, with the ARB edges unable to exchange subunits, then the two edges of each ARB should move at the same rate. On the other hand, if the exchange is at the ARB edges, then, from data from microtubules in vitro, the poleward edge should move much faster than the kinetochoreward edge. We found that the two edges of the ARB move at the same rate about half the time, but half the time they do not. Second, we studied the behaviour of two ARBs on a single fibre. If ARB motion is due solely to subunit addition at the kinetochore and loss at the pole, then the two ARBs must move poleward together. We found that after two ARBs are formed on a single fibre the region between the ARBs is unstable and rapidly depolymerizes. These results do not fit either model and suggest that influences of kinetochores and poles or other factors need to be considered that are not duplicated in experiments on microtubules in vitro.

Oxytocin analogues with non-coded amino acid residues in position 8: [8-Neopentylglycine]oxytocin and [8-cycloleucine]oxytocin

1987 ◽  
Vol 52 (9) ◽  
pp. 2317-2325 ◽  
Author(s):  
Jan Hlaváček ◽  
Jan Pospíšek ◽  
Jiřina Slaninová ◽  
Walter Y. Chan ◽  
Victor J. Hruby
Keyword(s):  
Amino Acid ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
The Other ◽  
Amino Acid Residues ◽  
Phase Synthesis ◽  
Other Hand ◽  
Fragment Condensation

[8-Neopentylglycine]oxytocin (II) and [8-cycloleucine]oxytocin (III) were prepared by a combination of solid-phase synthesis and fragment condensation. Both analogues exhibited decreased uterotonic potency in vitro, each being about 15-30% that of oxytocin. Analogue II also displayed similarly decreased uterotonic potency in vivo and galactogogic potency. On the other hand, analogue III exhibited almost the same potency as oxytocin in the uterotonic assay in vivo and in the galactogogic assay.

Nerve autofluorescence in near-ultraviolet light markedly enhances nerve visualization in vivo

2021 ◽  
Author(s):  
Fernando Dip ◽  
Pedro Bregoli ◽  
Jorge Falco ◽  
Kevin P. White ◽  
Raúl J. Rosenthal
Keyword(s):  
Ultraviolet Light ◽  
Near Ultraviolet

In vitro insulin-mimetic activity and in vivo metallokinetic feature of oxovanadium(IV)porphyrin complexes in healthy rats

2012 ◽  
Vol 16 (01) ◽  
pp. 114-121 ◽  
Author(s):  
Tapan K. Saha ◽  
Yutaka Yoshikawa ◽  
Hirouki Yasui ◽  
Hiromu Sakurai
Keyword(s):  
The Other ◽  
Insulin Mimetic ◽  
Other Hand ◽  
Better Than

We prepared [meso-tetrakis(4-carboxylatophenyl)porphyrinato]oxovanadium(IV) tetrasodium, ([VO(tcpp)]Na4), and investigated its in vitro insulin-mimetic activity and in vivo metallokinetic feature in healthy rats. The results were compared with those of previously proposed insulin-mimetic oxovanadium(IV)porphyrin complexes and oxovanadium(IV) sulphate. The in vitro insulin-mimetic activity and bioavailability of [VO(tcpp)]Na4 were considerably better than those of [meso-tetrakis (1-methylpyridinium-4-yl)porphyrinato]oxovanadium(IV)(4+) tetraperchlorate ([VO(tmpyp)](ClO4)4) and oxovanadium(IV) sulphate. On the other hand, [VO(tcpp)]Na4 and [meso-tetrakis(4-sulfonatophenyl) porphyrinato]oxidovanadate(IV)(4-)([VO(tpps)]) showed very similar in vitro insulin-mimetic activity and in vivo metallokinetic feature in healthy rats. In particular, the order of in vitro insulin-mimetic activity of the complexes was determined to be: [VO(tcpp)]Na4 ≈ [VO(tpps)] > ([VO(tmpyp)](ClO4)4 > oxovanadium(IV) sulphate.

Sex-chromosome anaphase movements in crane-fly spermatocytes are coordinated: ultraviolet microbeam irradiation of one kinetochore of one sex chromosome blocks the movements of both sex chromosomes

1987 ◽  
Vol 88 (4) ◽  
pp. 441-452
Author(s):  
JULIA A. M. SWEDAK ◽  
ARTHUR FORER
Keyword(s):  
Sex Chromosomes ◽  
Sex Chromosome ◽  
The Other ◽  
Signal System ◽  
Spindle Fibre ◽  
Spindle Axis ◽  
Ultraviolet Microbeam ◽  
Block Motion ◽  
Block Movement ◽  
Spindle Fibres

Sex chromosomes in crane-fly spermatocytes move polewards at anaphase after the autosomes have reached the poles. In Nephrotoma abbreviate the sex chromosomes are 8 μm long by 3.5 μm wide and have two orientations when they move: the long axis of the sex chromosome is either perpendicular or parallel to the spindle axis. We assume (1) that when a sex chromosome is perpendicular to the spindle axis it has a chromosomal spindle fibre to each pole, one from each kinetochore, as in other species; and (2) that when a sex chromosome is parallel to the spindle axis each kinetochore has spindle fibres to both poles, i.e. that the latter sex chromosomes are maloriented. We irradiated one kinetochore of one sex chromosome using an ultraviolet microbeam. When both sex chromosomes were normally oriented, irradiation of a single kinetochore permanently blocked movement of both sex chromosomes. Irradiation of non-kinetochore chromosomal regions or of spindle fibres did not block movement, or blocked movement only temporarily. We argue that ultraviolet irradiation of one kinetochore blocks movement of both sex chromosomes because of effects on a ‘signal’ system. The results were different when one sex chromosome was maloriented. Irradiation of one kinetochore of a maloriented sex chromosome did not block motion of either sex chromosome. On the other hand, irradiation of one kinetochore of a normally oriented sex chromosome permanently blocked motion of both that sex chromosome and the maloriented sex chromosome. We argue that for the signal system to allow the sex chromosomes to move to the pole each sex chromosome must have one spindle fibre to each pole.

scholarly journals Seminal vesicle proteins SVS3 and SVS4 facilitate SVS2 effect on sperm capacitation

Reproduction ◽  
2016 ◽  
Vol 152 (4) ◽  
pp. 313-321 ◽  
Author(s):  
Naoya Araki ◽  
Natsuko Kawano ◽  
Woojin Kang ◽  
Kenji Miyado ◽  
Kaoru Yoshida ◽  
...  
Keyword(s):  
Seminal Vesicle ◽  
Reproductive Tract ◽  
Female Reproductive Tract ◽  
The Other ◽  
Sperm Capacitation ◽  
Other Hand ◽  
Sperm Membrane ◽  
Vesicle Secretion ◽  
Mammalian Spermatozoa

Mammalian spermatozoa acquire their fertilizing ability in the female reproductive tract (sperm capacitation). On the other hand, seminal vesicle secretion, which is a major component of seminal plasma, inhibits the initiation of sperm capacitation (capacitation inhibition) and reduces the fertility of the capacitated spermatozoa (decapacitation). There are seven major proteins involved in murine seminal vesicle secretion (SVS1-7), and we have previously shown that SVS2 acts as both a capacitation inhibitor and a decapacitation factor, and is indispensable forin vivofertilization. However, the effects of SVSs other than SVS2 on the sperm have not been elucidated. Since mouseSvs2–Svs6genes evolved by gene duplication belong to the same gene family, it is possible that SVSs other than SVS2 also have some effects on sperm capacitation. In this study, we examined the effects of SVS3 and SVS4 on sperm capacitation. Our results showed that both SVS3 and SVS4 are able to bind to spermatozoa, but SVS3 alone showed no effects on sperm capacitation. On the other hand, SVS4 acted as a capacitation inhibitor, although it did not show decapacitation abilities. Interestingly, SVS3 showed an affinity for SVS2 and it facilitated the effects of SVS2. Interaction of SVS2 and spermatozoa is mediated by the ganglioside GM1 in the sperm membrane; however, both SVS3 and SVS4 had weaker affinities for GM1 than SVS2. Therefore, we suggest that separate processes may cause capacitation inhibition and decapacitation, and SVS3 and SVS4 act on sperm capacitation cooperatively with SVS2.

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