Analysis of chromosome movement in crane fly spermatocytes by ultraviolet microbeam irradiation of individual chromosomal spindle fibres. II. Action spectra for stopping chromosome movement and for blocking ciliary beating and myofibril contractions

1981 ◽  
Vol 59 (9) ◽  
pp. 777-792 ◽  
Author(s):  
Peggy J. Sillers ◽  
Arthur Forer
Keyword(s):  
Absorption Spectra ◽  
Ultraviolet Light ◽  
Action Spectrum ◽  
Chromosome Movement ◽  
Ciliary Beating ◽  
Action Spectra ◽  
Light Passing ◽  
Block Movement ◽  
Two Peaks ◽  
Spindle Fibres

Chromosome-to-pole movement in crane fly spermatocytes was temporarily blocked by ultraviolet light focussed to a 4-μm-diameter spot on single chromosomal spindle fibres. Since similar irradiation of the interzonal region did not alter chromosome-to-pole movement, this effect was specific to spindle fibres. The action spectrum for blocking chromosome movement in this specific way had two peaks, one at 270 nm and one at 290 nm. To block movement, irradiations with 280-nm-wavelength light required two to four times more energy than irradiations with 270- or 290-nm-wavelength light.Action spectra were obtained for blocking ciliary beating and for blocking myofibril contraction. The action spectrum for blocking ciliary beating had a broad peak, between 260 nm and 280 nm, whilst that for blocking myofibril contraction had two peaks, at 270 and 290 nm, just like that for blocking chromosome movement. We discuss the similarities and differences in the various action spectra, and we compare the action spectra to absorption spectra of spindle components and to other action spectra (e.g., that for depolymerizing actin-containing filaments).Absorption spectra were obtained for ultraviolet light passing through spindle fibres as well as for ultraviolet light passing through the interzone.

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.

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 PHOTOSYNTHETIC ACTION SPECTRA OF MARINE ALGAE

1950 ◽  
Vol 33 (4) ◽  
pp. 389-422 ◽  
Author(s):  
F. T. Haxo ◽  
L. R. Blinks
Keyword(s):  
Absorption Spectra ◽  
Green Algae ◽  
Red Algae ◽  
Marine Algae ◽  
Monochromatic Light ◽  
Action Spectrum ◽  
Water Soluble ◽  
Good Correspondence ◽  
Oxygen Determination ◽  
Action Spectra

A polarographic oxygen determination, with tissue in direct contact with a stationary platinum electrode, has been used to measure the photosynthetic response of marine algae. These were exposed to monochromatic light, of equal energy, at some 35 points through the visible spectrum (derived from a monochromator). Ulva and Monostroma (green algae) show action spectra which correspond very closely to their absorption spectra. Coilodesme (a brown alga) shows almost as good correspondence, including the spectral region absorbed by the carotenoid, fucoxanthin. In green and brown algae, light absorbed by both chlorophyll and carotenoids seems photosynthetically effective, although some inactive absorption by carotenoids is indicated. Action spectra for a wide variety of red algae, however, show marked deviations from their corresponding absorption spectra. The photosynthetic rates are high in the spectral regions absorbed by the water-soluble "phycobilin" pigments (phycoerythrin and phycocyanin), while the light absorbed by chlorophyll and carotenoids is poorly utilized for oxygen production. In red algae containing chiefly phycoerythrin, the action spectrum closely resembles that of the water-extracted pigment, with peaks corresponding to its absorption maxima (495, 540, and 565 mµ). Such algae include Delesseria, Schizymenia, and Porphyrella. In the genus Porphyra, there is a series P. nereocystis, P. naiadum, and P. perforata, with increasingly more phycocyanin and less phycoerythrin: the action spectra reflect this, with increasing activity in the orange-red region (600 to 640 mµ) where phycocyanin absorbs. In all these red algae, photosynthesis is almost minimal at 435 mµ and 675 mµ, where chlorophyll shows maximum absorption. Although the chlorophylls (and carotenoids) are present in quantities comparable to the green algae, their function is apparently not that of a primary light absorber; this role is taken over by the phycobilins. In this respect the red algae (Rhodophyta) appear unique among photosynthetic plants.

scholarly journals Electronic Spectroscopy of Isolated DNA Polyanions

2018 ◽  
Author(s):  
Steven Daly ◽  
Massimiliano Porrini ◽  
Frédéric Rosu ◽  
Valerie Gabelica
Keyword(s):  
Gas Phase ◽  
Charge State ◽  
Absorption Spectra ◽  
Action Spectrum ◽  
Binding Energies ◽  
Action Spectroscopy ◽  
Action Spectra ◽  
Vis Spectroscopy ◽  
Electron Binding Energies ◽  
Electron Binding

In solution, UV-vis spectroscopy is often used to investigate structural changes in biomolecules (i.e., nucleic acids), owing to changes in the environment of their chromophores (i.e., the nucleobases). Here we address whether action spectroscopy could achieve the same for gas-phase ions, while taking the advantage of additional spectrometric separation of complex mixtures. We therefore systematically studied the action spectroscopy of homo-base 6-mer DNA strands (dG6, dA6, dC6, dT6) and discuss the results in light of gas-phase structures validated by ion mobility spectrometry and infrared ion spectroscopy, of electron binding energies measured by photoelectron spectroscopy, and of calculated electronic photo-absorption spectra. When UV photons interact with oligonucleotide polyanions, two main actions may take place: (1) fragmentation and (2) electron detachment. The action spectra reconstructed from fragmentation follow the absorption spectra well, and result from multiple cycles of absorption and internal conversion. The action spectra reconstructed from the electron photodetachment (ePD) efficiency reveal interesting phenomena: ePD depends on the charge state because it depends on electron binding energies. We illustrate with the G-quadruplex [dTG4T]4 that the ePD action spectrum shifts with the charge state, pointing to possible caveats when comparing the spectra of systems having different charge densities to deduce structural parameters. Moreover, ePD is particularly efficient for purines but not pyrimidines. ePD thus reflects not only absorption, but also particular relaxation pathways of the electronic excited states. As these pathways lead to photo-oxidation, their investigation on model gas-phase systems may prove useful to elucidate mechanisms of photo-oxidative damages, which are linked to mutations and cancers.

scholarly journals Electronic Spectroscopy of Isolated DNA Polyanions

2018 ◽  
Author(s):  
Steven Daly ◽  
Massimiliano Porrini ◽  
Frédéric Rosu ◽  
Valerie Gabelica
Keyword(s):  
Gas Phase ◽  
Charge State ◽  
Absorption Spectra ◽  
Action Spectrum ◽  
Binding Energies ◽  
Action Spectroscopy ◽  
Action Spectra ◽  
Vis Spectroscopy ◽  
Electron Binding Energies ◽  
Electron Binding

In solution, UV-vis spectroscopy is often used to investigate structural changes in biomolecules (i.e., nucleic acids), owing to changes in the environment of their chromophores (i.e., the nucleobases). Here we address whether action spectroscopy could achieve the same for gas-phase ions, while taking the advantage of additional spectrometric separation of complex mixtures. We therefore systematically studied the action spectroscopy of homo-base 6-mer DNA strands (dG6, dA6, dC6, dT6) and discuss the results in light of gas-phase structures validated by ion mobility spectrometry and infrared ion spectroscopy, of electron binding energies measured by photoelectron spectroscopy, and of calculated electronic photo-absorption spectra. When UV photons interact with oligonucleotide polyanions, two main actions may take place: (1) fragmentation and (2) electron detachment. The action spectra reconstructed from fragmentation follow the absorption spectra well, and result from multiple cycles of absorption and internal conversion. The action spectra reconstructed from the electron photodetachment (ePD) efficiency reveal interesting phenomena: ePD depends on the charge state because it depends on electron binding energies. We illustrate with the G-quadruplex [dTG4T]4 that the ePD action spectrum shifts with the charge state, pointing to possible caveats when comparing the spectra of systems having different charge densities to deduce structural parameters. Moreover, ePD is particularly efficient for purines but not pyrimidines. ePD thus reflects not only absorption, but also particular relaxation pathways of the electronic excited states. As these pathways lead to photo-oxidation, their investigation on model gas-phase systems may prove useful to elucidate mechanisms of photo-oxidative damages, which are linked to mutations and cancers.

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 Electronic Spectroscopy of Isolated DNA Polyanions

2018 ◽  
Author(s):  
Steven Daly ◽  
Massimiliano Porrini ◽  
Frédéric Rosu ◽  
Valerie Gabelica
Keyword(s):  
Gas Phase ◽  
Absorption Spectra ◽  
Ion Mobility ◽  
Photoelectron Spectroscopy ◽  
Binding Energies ◽  
Action Spectroscopy ◽  
Action Spectra ◽  
Vis Spectroscopy ◽  
Electron Binding Energies ◽  
Electron Binding

In solution, UV-vis spectroscopy is often used to investigate structural changes in biomolecules (i.e., nucleic acids), owing to changes in the environment of their chromophores (i.e., the nucleobases). Here we address whether action spectroscopy could achieve the same for gas-phase ions, while taking the advantage of additional mass spectrometry and ion mobility separation of complex mixtures. We therefore systematically studied the action spectroscopy of homo-base 6-mer DNA strands (dG6, dA6, dC6, dT6), and discuss the results in light of gas-phase structures validated by ion mobility spectrometry and infrared ion spectroscopy, and in light of electron binding energies measured by photoelectron spectroscopy, and calculated electronic photo-absorption spectra. When UV photons interact with oligonucleotide polyanions, two main actions may take place: (1) fragmentation and (2) electron detachment. The action spectra reconstructed from fragmentation follow the absorption spectra well, and result from multiple cycles of absorption and internal conversion. The action spectra reconstructed from the electron photodetachment (EPD) efficiency reveal interesting phenomena: EPD depends on the charge state in a manner depending on electron binding energies, and is particularly efficient for purines but not pyrimidines. EPD thus reflects not only absorption, but also particular relaxation pathways of the electronic excited states. As these pathways lead to photo-oxidation, their investigation on model gas-phase systems may prove useful to elucidate mechanisms of photo-oxidative damages, which are linked to mutations and cancers.

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