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Journal articles on the topic 'Metaphase arrangement'
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1
Beçak, Maria Luiza, Willy Beçak, and Alexandre Pereira. "Somatic pairing, endomitosis and chromosome aberrations in snakes (Viperidae and Colubridae)." Anais da Academia Brasileira de Ciências 75, no. 3 (2003): 285–300. http://dx.doi.org/10.1590/s0001-37652003000300004.
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The positioning of macrochromosomes of Bothrops jararaca and Bothrops insularis (Viperidae) was studied in undistorted radial metaphases of uncultured cells (spermatogonia and oogonia) not subjected to spindle inhibitors. Colchicinized metaphases from uncultured (spleen and intestine) and cultured tissues (blood) were also analyzed. We report two antagonic non-random chromosome arrangements in untreated premeiotic cells: the parallel configuration with homologue chromosomes associated side by side in the metaphase plate and the antiparallel configuration having homologue chromosomes with antipolar distribution in the metaphase ring. The antiparallel aspect also appeared in colchicinized cells. The spatial chromosome arrangement in both configurations is groupal size-dependent and maintained through meiosis. We also describe, in untreated gonia cells, endomitosis followed by reductional mitosis which restores the diploid number. In B. jararaca males we observed that some gonad regions present changes in the meiotic mechanism. In this case, endoreduplicated cells segregate the diplochromosomes to opposite poles forming directly endoreduplicated second metaphases of meiosis with the suppression of first meiosis. By a successive division, these cells form nuclei with one set of chromosomes. Chromosome doubling in oogonia is known in hybrid species and in parthenogenetic salamanders and lizards. This species also presented chromosome rearrangements leading to aneuploidies in mitosis and meiosis. It is suggested that somatic pairing, endomitosis, meiotic alterations, and chromosomal aberrations can be correlated processes. Similar aspects of nuclei configurations, endomitosis and reductional mitosis were found in other Viperidae and Colubridae species.
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Goicoechea, P. G., A. Roca, A. R. Linde, T. Naranjo, and R. Giraldez. "Independent arrangement of bivalents and (or) quadrivalents in linear meiotic metaphase plates of rye." Genome 34, no. 3 (1991): 421–29. http://dx.doi.org/10.1139/g91-064.
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The relative positioning of bivalents and (or) quadrivalents in flattened lateral views of metaphase I (linear metaphase plates) has been analyzed in three different plant types of rye: normal plants (type 1); heterozygotes for translocation T305W (type 2); and double heterozygotes for translocations T305W and TR01 (type 3). In all plant types all bivalents and (or) quadrivalents were identified using C-banding. The results indicate that quadrivalents show a preference towards being located in marginal positions of the linear plate, and there are also differences in position preferences between specific bivalents. Adjacently oriented quadrivalents and rod bivalents show a stronger preference for marginal positions than alternate quadrivalents and ring bivalents, respectively, but this does not indicate the existence of a fixed or ordered arrangement of chromosomes in the spindle since bivalents and (or) quadrivalents are independently located relative to each other.Key words: Secale, meiosis, metaphase, arrangement, multivalents, bivalents.
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Kaur, Harbhajan, and Vikas Suman. "Chromosomes and their meiotic behaviour in two species of Dieuches Dohrn, 1860 (Heteroptera: Lygaeidae: Rhyparochromini)." Comparative Cytogenetics 3, no. (1) (2009): 43–50. https://doi.org/10.3897/compcytogen.v3i1.7.
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The Lygaeidae (Heteroptera) are a large and diverse family in which the male diploid chromosomal complement ranges from 10 to 30. Diploid numbers of 14 and 16 are taken as two modal numbers of the family. The Rhyparochrominae, one of the largest subfamilies of the Lygaeidae, are known to be heterogeneous both cytologically and morphologically. Available data on the tribe Rhyparochromini reveal that all species are characterized by the presence of a pair of microchromosomes (m-chromosomes) and have an XY/XX (♂/♀) sex chromosome determining system.<em> Dieuches</em> <em>coloratus</em> (Distant, 1909) and <em>D. insignis </em>(Distant, 1918) belonging to Rhyparochromini, have 2n=14=10A+2m+XY and<em> </em>2n=12=8A+2m+XY respectively. Both the species are similar inone pair of distinctly large autosomes in their chromosome complements. The metaphase plate arrangement of autosomes, sex chromosomes and m-chromosomes in <em>D. coloratus</em> is similar to the common condition observed in the tribe Rhyparochromini. In <em>D. insignis,</em> however, the arrangement is different. Here<em>, </em>metaphase I<em> </em>is usual in showing peripheral position of autosomes and central position of sex chromosomes and m-chromosomes. At metaphase II, however, autosomes, sex chromosomes and m-chromosomes are peripherally placed, an arrangement, which is not reported earlier in the tribe Rhyparochromini.
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Schubert, Veit, Mateusz Zelkowski, Sonja Klemme, and Andreas Houben. "Similar Sister Chromatid Arrangement in Mono- and Holocentric Plant Chromosomes." Cytogenetic and Genome Research 149, no. 3 (2016): 218–25. http://dx.doi.org/10.1159/000447681.
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Due to the X-shape formation at somatic metaphase, the arrangement of the sister chromatids is obvious in monocentric chromosomes. In contrast, the sister chromatids of holocentric chromosomes cannot be distinguished even at mitotic metaphase. To clarify their organization, we differentially labelled the sister chromatids of holocentric Luzula and monocentric rye chromosomes by incorporating the base analogue EdU during replication. Using super-resolution structured illumination microscopy (SIM) and 3D rendering, we found that holocentric sister chromatids attach to each other at their contact surfaces similar to those of monocentrics in prometaphase. We found that sister chromatid exchanges (SCEs) are distributed homogeneously along the whole holocentric chromosomes of Luzula, and that their occurrence is increased compared to monocentric rye chromosomes. The SCE frequency of supernumerary B chromosomes, present additionally to the essential A chromosome complement of rye, does not differ from that of A chromosomes. Based on these results, models of the sister chromatid arrangement in mono- and holocentric plant chromosomes are presented.
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Zhao, Jian, Shaobo Jin, and Shui Hao. "The substructural organization of the chromosome core (scaffold) in meiotic chromosomes of Trilophidia annulata." Genetical Research 64, no. 3 (1994): 209–15. http://dx.doi.org/10.1017/s0016672300032869.
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SummaryThe substructural organization of chromosome cores or nonhistone proteins was studied within intact metaphase chromosomes at the second meiotic division in the grasshopper Trilophidia annulata by silver staining as well as light microscopy and whole mount electron microscopy of squash chromosomes. Our results revealed that the metaphase II chromosome contains a longitudinal, helical coiling core structure. Probably the two last organizational levels of the core packaging are achieved by helical coiling. The core structure retains the morphological characteristics of the original metaphase chromosome, surrounded by a halo of dispersed materials, which may be composed mainly of nonhistone proteins. The kinetochore is found to be connected with the chromosome core. The present findings combined with our previous observations on the helical structure of metaphase II chromosomes suggest that the folding path of the internal core structure in metaphase chromosomes is consistent with the final helical arrangement of the chromosome itself. These observations also imply that in condensed metaphase chromosomes nonhistone protein may form a compact network structure with helical appearance, which extends throughout the entire chromosome.
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Harrison, C. J., E. M. Jack, T. D. Allen, and R. Harris. "Light and scanning electron microscopy of the same human metaphase chromosomes." Journal of Cell Science 77, no. 1 (1985): 143–53. http://dx.doi.org/10.1242/jcs.77.1.143.
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A technique has been developed to examine the same G-banded human metaphase chromosomes, first in the light microscope and then in the scanning electron microscope (SEM). A structural involvement in chromosome banding was confirmed by a positional correlation between the G-positive bands observed in the light microscope and the circumferential grooves between the quaternary coils of the metaphase chromosomes, observed in the SEM. In further support of this the regions between the grooves showed a positional relationship with the G-negative or reverse (R) bands. The examination of slightly extended metaphase chromosomes in the light microscope demonstrated that the G-banding pattern corresponded to that described by the Paris nomenclature for metaphase chromosomes. The arrangement of the circumferential grooves of the same chromosomes, observed in the SEM, was shown to relate to that described by the Paris nomenclature for prometaphase chromosomes. Therefore, using the SEM it is possible to demonstrate the details of prometaphase banding in metaphase chromosomes.
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Lukhtanov, Vladimir A. "Two types of highly ordered micro- and macrochromosome arrangement in metaphase plates of butterflies (Lepidoptera)." Comparative Cytogenetics 13, no. 1 (2019): 19–25. http://dx.doi.org/10.3897/compcytogen.v13i1.32614.
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In karyotype of many organisms, chromosomes form two distinct size groups: macrochromosomes and microchromosomes. During cell divisions, the position of the macro- and microchromosomes is often ordered within metaphase plate. In many reptiles, amphibians, birds, insects of the orthopteran family Tettigoniidae and in some plants, a so called “reptilian” type organization is found, with microchromosomes situated in the center of metaphase plate and with macrochromosomes situated at the periphery. An opposite, “lepidopteran” type is known in butterflies and moths (i.e. in the order Lepidoptera) and is characterized by macrochromosomes situated in the center and by microchromosomes situated at the periphery. The anomalous arrangement found in Lepidoptera was previously explained by holocentric organization of their chromosomes. Here I analyse the structure of meiotic metaphase I plates in ithomiine butterfly, Forbestraolivencia (H. Bates, 1862) (Nymphalidae, Danainae, Ithomiini) which has a clear “reptilian” organization, contrary to previous observations in Lepidoptera. In this species large bivalents (i.e. macrochromosomes) form a regular peripheral circle, whereas the minute bivalents (i.e. microchromosomes) occupy the center of this circle. The reasons and possible mechanisms resulting in two drastically different spatial chromosome organization in butterflies are discussed.
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Lukhtanov, Vladimir A. "Two types of highly ordered micro- and macrochromosome arrangement in metaphase plates of butterflies (Lepidoptera)." Comparative Cytogenetics 13, no. (1) (2019): 19–25. https://doi.org/10.3897/CompCytogen.v13i1.32614.
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In karyotype of many organisms, chromosomes form two distinct size groups: macrochromosomes and microchromosomes. During cell divisions, the position of the macro- and microchromosomes is often ordered within metaphase plate. In many reptiles, amphibians, birds, insects of the orthopteran family Tettigoniidae and in some plants, a so called "reptilian" type organization is found, with microchromosomes situated in the center of metaphase plate and with macrochromosomes situated at the periphery. An opposite, "lepidopteran" type is known in butterflies and moths (i.e. in the order Lepidoptera) and is characterized by macrochromosomes situated in the center and by microchromosomes situated at the periphery. The anomalous arrangement found in Lepidoptera was previously explained by holocentric organization of their chromosomes. Here I analyse the structure of meiotic metaphase I plates in ithomiine butterfly, Forbestra olivencia (H. Bates, 1862) (Nymphalidae, Danainae, Ithomiini) which has a clear "reptilian" organization, contrary to previous observations in Lepidoptera. In this species large bivalents (i.e. macrochromosomes) form a regular peripheral circle, whereas the minute bivalents (i.e. microchromosomes) occupy the center of this circle. The reasons and possible mechanisms resulting in two drastically different spatial chromosome organization in butterflies are discussed.
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Yacobi, Y. Z., H. Levanony, and M. Feldman. "An ordered arrangement of bivalents at first meiotic metaphase of wheat." Chromosoma 91, no. 5 (1985): 347–54. http://dx.doi.org/10.1007/bf00291006.
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Yacobi, Y. Z., H. Levanony, and M. Feldman. "An ordered arrangement of bivalents at first meiotic metaphase of wheat." Chromosoma 91, no. 5 (1985): 355–58. http://dx.doi.org/10.1007/bf00291007.
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Hamkalo, B. A., and Elizabeth R. Unger. "Histochemical aspects of nucleic acid detection." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 746–47. http://dx.doi.org/10.1017/s0424820100140105.
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This symposium brings together several approaches for the detection of specific nucleic acid sequences that have potential applications at the histochemical level.Trask et al. report on the use of fluorescence in situ hybridization (FISH) techniques to study the arrangement of DNA sequences in normal and diseaserelated chromosomes. The sites of specific DNA sequences can be fluorescently tagged. Different sequences can be labeled with different fluorochromes so that their arrangement can be studied using fluorescence microscopy. The distances between points on the same or different chromosomes can be determined in a large number of interphase nuclei or metaphase chromosomes. A variety of probe types, ranging from single-copy sequences to highly repeated sequences can be employed.Hamkalo and co-workers have used non-radioactive methods at the EM level for the detection of nucleic acid sequences by in situ hybridization. Analysis of metaphase chromosomes by electron microscopy allows for high resolution mapping of chromosomes. A variety of labelling procedures have been employed to illustrate the utility of high resolution nucleic acid sequence mapping in these preparations.
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Kaur, Harbhajan, and B. Semahagn. "Meiotic behaviour of chromosomes in three predator species of the subfamily Asopinae (Heteroptera: Pentatomidae)." Comparative Cytogenetics 4, no. (2) (2010): 133–39. https://doi.org/10.3897/compcytogen.v4i2.47.
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The study of chromosome behaviour has been carried out on males of three species of the Asopinae (Pentatomidae) bugs <em>Andrallus spinidens</em> (Fabricius, 1787), <em>Canthecona furcellata</em> Wolff, 1801 and <em>Perillus bioculatus</em> (Fabricius, 1775) collected in India. All the species have XY sex chromosome system and 12 autosomes (2n=14=12A+XY). The general course of meiosis is fairly uniform and is typical for heteropteran species. However, the species differ in the extent of decondensation of the autosomes during the diffuse stage and the number of ring bivalents at diplotene/diakinesis. Also, a metaphase I arrangement of chromosomes which is different from the typical Pentatomidae type has been observed in <em>C. furcellata</em> and <em>P. bioculatus.</em>
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MOSS, JANET M., and BRIAN G. MURRAY. "The three-dimensional arrangement of chromosomes at meiotic metaphase I in normal and interchange heterozygotes of Briza humilis." Journal of Cell Science 97, no. 3 (1990): 565–70. http://dx.doi.org/10.1242/jcs.97.3.565.
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Pollen mother cells at metaphase I have been reconstructed from serial sections in normal and interchange heterozygotes of Briza humilis. The pollen mother cells have an irregular shape with a prominent projection from the tangential face into the anther loculus. The seven bivalents of the normal plant are usually arranged with one bivalent in a central position surrounded by a ring of the remaining six or as a ring of all seven bivalents. The central:peripheral distribution of quadrivalents is different in two different interchange plants; in a sector analysis, where cells are divided into four quarters relative to the tangential face of the pollen mother cell, the two plants also show differences in quadrivalent distribution, indicating that individual chromosomes occupy different positions in the cell. The relevance of these results to the positioning of quadrivalents in lateral squashes of meiotic metaphase I are discussed.
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Mullinger, A. M., and R. T. Johnson. "Disassembly of the mammalian metaphase chromosome into its subunits: studies with ultraviolet light and repair synthesis inhibitors." Journal of Cell Science 87, no. 1 (1987): 55–69. http://dx.doi.org/10.1242/jcs.87.1.55.
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Metaphase chromosomes of a simian virus-transformed Indian muntjac cell line have been examined by scanning electron microscopy of material in which the fully packed metaphase structure is progressively relaxed. Such chromosomes are seen in standard, spread preparations of ultraviolet light-irradiated, metaphase-arrested cells, which have been incubated in the presence of inhibitors of DNA synthesis; they are processed for electron microscopy by trypsinization, further fixation and osmium impregnation. Decondensation is initially associated with a gradual elongation and loosening of the chromosome axis and, as loosening proceeds, the appearance of unexpected higher order structures—clusters of 20–40 nm diameter fibres. The arrangement of the clusters shows much variation between spreads. In the most fully extended chromosomes clusters are arranged in two longitudinal series with pairing between sister chromatids; the diameter of the majority of clusters in such chromosomes is in the range 0.4-0.6 micron. In the final stages of decondensation, clusters separate and individual chromosomes are no longer recognizable. Similar fibre clusters are found in interphase nuclei prepared by the same method. We suggest that the clusters of chromatin fibres may assemble as intermediates in the construction of an axial structure, which is further compacted in the fully condensed metaphase chromosome.
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Angus, Robert. "Unusual arrangement and behaviour of the sex chromosomes of Aphodius (Agolius) abdominalis Bonelli, 1812, and comparison with A. (A.) bonvouloiri Harold, 1860 (Coleoptera: Aphodiidae)." Comparative Cytogenetics 3, no. (2) (2009): 91–96. https://doi.org/10.3897/compcytogen.v3i2.15.
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<em>Aphodius abdominalis</em> Bonelli, 1812 is shown to have a karyotype comprising nine pairs of autosomes and sex chromosomes which are X0 (male), XX (female). At first metaphase of meiosis the X chromosome is linked to an autosomal bivalent by a darkly staining area of the cytoplasm, resembling the Xy p arrangement typical of <em>Aphodius</em> species, but giving nine, rather than 10, elements in the nucleus. C-banding, which shows the centromeres, confirms this unusual arrangement. <em>A. bonvouloiri</em>, the only other known species of subgenus <em>Agolius</em> Mulsant et Rey, 1869, has a male karyotype with nine pairs of autosomes and Xy sex chromosomes. No preparations of its meiosis are available.
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Kazimierski, T., and E. M. Kazimierska. "Iivestigations on hybrids in the genus Trifolium L. V. Fertility and cytogenetics of the hybrid Trifolium nigrescences Viv. x T. isthomocarpum Brot." Acta Societatis Botanicorum Poloniae 42, no. 4 (2015): 567–89. http://dx.doi.org/10.5586/asbp.1973.044.
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<i>T.nigrescens</i> (2n = 16) crosses with <i>T .isthomocarpum</i> (2n = 16) reciprocally. The viability of hybrid seedlings depend from the direction of the cross. At the time of diakinesis and metaphase I the average chromosome figures per PMC's was 7.014<sub>II</sub>, 0.005<sub>III</sub>, 0.435<sub>IV</sub> and 0.209<sub>I</sub>. For one half of the PMC's in the metaphase I the typical chromosome arrangement was 8<sub>II</sub>. The F<sub>1</sub> plants was almost completly sterile. The causes of viability of hybrid seedlings depending on the direction of the cross, and the sterility of hybrid plants, are discussed.
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Luetjens, Craig Marc, and Adriaan W. C. Dorresteijn. "Dynamic changes of the microtubule system corresponding to the unequal and spiral cleavage modes in the embryo of the zebra mussel, Dreissena polymorpha (Mollusca, Bivalvia)." Zygote 6, no. 3 (1998): 239–48. http://dx.doi.org/10.1017/s0967199498000185.
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Unequal cleavage requires a highly organised cytoskeleton. We investigated the localisation of both tubulins and microtubular arrays in Dreissena eggs during and after fertilisation using confocal laser scanning microscopy. Freshly spawned eggs are arrested in metaphase I. A maternal pool of γ-tubulin is found mainly in the centre of the asters of the meiotic spindle. The paternal pool of γ-tubulin, present in the fertilising sperm, could not be traced within the egg, but a microtubule-organising centre forms near the male pronucleus at anaphase II. Male and female pronuclei grow as they migrate in the wake of their aster and rendezvous. First cleavage is unequal and starts without pronuclear fusion. At metaphase the two equal-sized asters span the entire egg in a symmetrical arrangement. At late metaphase the spindle shifts along its longitudinal axis into an eccentric position and the peripheral aster takes on an umbrella-like appearance, whereas the central aster remains spherical. The cleavage furrow becomes determined in the circumferential overlap of the asters. The inequality at second cleavage, however, is due to the unequal size of the asters. The third cleavage spindle also has asymmetrical asters and spindle shift was only observed in the D-cell. The spiral character is a result of an asymmetrical organisation of the larger, vegetal aster. Our results show that the arrangement of the γ-tubulin clusters and of microtubules changes and develops during early development of Dreissena in a way that can explain the axis-generating asymmetries in cell pattern and the spiral sense of cleavage. The major cytological characters expected to direct pattern formation in this phase of development are: size, position, and symmetry or asymmetry of both spindle and asters.
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Plaja, A., R. Miro, E. Lloveras, E. Sarret, B. Fernandez, and J. Egozcue. "Intranuclear arrangement of human chromosome 12 is reflected in metaphase chromosomes as non-random bending." Annales de Génétique 47, no. 4 (2004): 429–32. http://dx.doi.org/10.1016/j.anngen.2004.07.002.
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Oud, J. L., and G. K. Rickards. "The spatial arrangement ofAllium triquetrum chain quadrivalents at metaphase I as viewed by confocal microscopy." Chromosoma 102, no. 10 (1993): 728–33. http://dx.doi.org/10.1007/bf00650900.
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Rizzi, E., M. Falconi, R. Rizzoli, et al. "High-resolution FEISEM detection of DNA centromeric probes in HeLa metaphase chromosomes." Journal of Histochemistry & Cytochemistry 43, no. 4 (1995): 413–19. http://dx.doi.org/10.1177/43.4.7897182.
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HeLa metaphase chromosome spreads were hybridized with centromeric biotinylated DNA probes and detected with gold-conjugated anti-biotin antibodies. Chromosomes were observed by an in-lens field emission scanning electron microscope (FEISEM), which permits detection of biological samples without any coating. DNA probes were well localized in the centromeric region of chromosomes and there was clear discrimination between 10 nm fibers that hybridized to DNA probes and those that did not hybridize. This approach shows that in situ hybridization can be directly visualized at the FEISEM level by evaluating only secondary electron emission, which allows physical localization of the hybridized probe with high resolution so that backscatter detection represents only a control. Because chromosomes maintain the 10-nm fiber organization after in situ hybridization procedures, our data suggest that this fiber represents the lowest order of chromatin arrangement that permits transitory DNA denaturation.
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CESAR PIRES BIONE, NILTON, MARIA SUELY PAGLIARINI, and LEONES ALVES DE ALMEIDA. "A male-sterile mutation in soybean (Glycine max) affecting chromosome arrangement in metaphase plate and cytokinesis." BIOCELL 29, no. 2 (2005): 177–81. http://dx.doi.org/10.32604/biocell.2005.29.177.
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Nakajima, Yuko, Anthony Cormier, Randall G. Tyers, et al. "Ipl1/Aurora-dependent phosphorylation of Sli15/INCENP regulates CPC–spindle interaction to ensure proper microtubule dynamics." Journal of Cell Biology 194, no. 1 (2011): 137–53. http://dx.doi.org/10.1083/jcb.201009137.
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Dynamic microtubules facilitate chromosome arrangement before anaphase, whereas during anaphase microtubule stability assists chromosome separation. Changes in microtubule dynamics at the metaphase–anaphase transition are regulated by Cdk1. Cdk1-mediated phosphorylation of Sli15/INCENP promotes preanaphase microtubule dynamics by preventing chromosomal passenger complex (CPC; Sli15/INCENP, Bir1/Survivin, Nbl1/Borealin, Ipl1/Aurora) association with spindles. However, whether Cdk1 has sole control over microtubule dynamics, and how CPC–microtubule association influences microtubule behavior, are unclear. Here, we show that Ipl1/Aurora-dependent phosphorylation of Sli15/INCENP modulates microtubule dynamics by preventing CPC binding to the preanaphase spindle and to the central spindle until late anaphase, facilitating spatiotemporal control of microtubule dynamics required for proper metaphase centromere positioning and anaphase spindle elongation. Decreased Ipl1-dependent Sli15 phosphorylation drives direct CPC binding to microtubules, revealing how the CPC influences microtubule dynamics. We propose that Cdk1 and Ipl1/Aurora cooperatively modulate microtubule dynamics and that Ipl1/Aurora-dependent phosphorylation of Sli15 controls spindle function by excluding the CPC from spindle regions engaged in microtubule polymerization.
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Wolf, Klaus Werner. "The spindle apparatus in early embryonic divisions of Ephestia Kuehniella Z. (Pyralidae, Lepidoptera) is formed by alignment of minispindles." Zygote 2, no. 1 (1994): 87–95. http://dx.doi.org/10.1017/s0967199400001805.
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SummarySpindles were isolated from deposited eggs of the Mediterranean mealmoth, Ephestia Kuehniella. Their structure and development were studied using anti-tubulin immunofluorescence. The microtubules were labelled with three different monoclonal antibodies. These were directed against β-tubulin, tyrosinated α-tubulin and acetylated α-tubulin. Significant differences in the staining behaviour were not detected with the three antibodies. An unusual mode of spindle formation was observed during the first mitotic division after fusion of the pronuclei. Several of the ensuing embryonic divisions may show the same phenomenon. Prophase of these divisions was characterised by an irregular arrangement of microtubules in the nuclear area. The microtubule mass in the nuclear area increased concomitantly with chromosome condensation. Microtubular foci, comparable to the forming asters of canonical spindles, were not detected. The formation of an orderly pattern in the microtubule mass was signalled by the appearance of minispindles apparently developing around individual chromosomes. Several minispindles subsequently aligned and formed metaphase-like entities within the nuclear area. The metaphase-like entities, in turn, aligned with one another and gave rise to a conventional bipolar metaphase spindle with small asters. The further development of the spindle was conventional. The chromosomes migrated towards the spindle poles and finally daughter nuclei formed. The anaphase and telophase spindles possessed both a prominent array of interzone microtubules and asters. The events in prophase of early embryonic mitosis of E. kuehniella may represent a rare case of chromosomeinduced spindle formation.
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Pandey, Archana, and Shyam R. Sakya. "Effect of triazophos on mitotic activity and chromosomal behavior in root meristems of Allium cepa L." Botanica Orientalis: Journal of Plant Science 6 (March 15, 2010): 4–7. http://dx.doi.org/10.3126/botor.v6i0.2903.
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Effect of triazophos (an organophosphorous insecticide) on mitotic activity and chromosomal behavior in the meristematic region of root tip cells of Allium cepa L. was assessed. The insecticide showed mitotic depression and positive chromo-toxic effects. Abnormalities, such as stickiness, plasmolysed cells, equatorial plate shifting, polar shifting, irregular chromosome arrangement, precocious arms formation, bridge formation, C-metaphase, fragmentation of chromosomes, unequal cytokinesis, diagonal cytokinesis, delayed cytokinesis and formation of binucleated cells, were recorded in the chemically pretreated root meristem. Key-words: chromosomal and cellular abnormalities; cytotoxic effect; mitotic index; phase indices.DOI: 10.3126/botor.v6i0.2903 Botanica Orientalis - Journal of Plant Science (2009) 6: 4-7
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Klein, Christophe, Thierry Cheutin, Marie-Françoise O’Donohue, et al. "The Three-dimensional Study of Chromosomes and Upstream Binding Factor-immunolabeled Nucleolar Organizer Regions Demonstrates Their Nonrandom Spatial Arrangement during Mitosis." Molecular Biology of the Cell 9, no. 11 (1998): 3147–59. http://dx.doi.org/10.1091/mbc.9.11.3147.
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The volumic rearrangement of both chromosomes and immunolabeled upstream binding factor in entire well-preserved mitotic cells was studied by confocal microscopy. By using high-quality three-dimensional visualization and tomography, it was possible to investigate interactively the volumic organization of chromosome sets and to focus on their internal characteristics. More particularly, this study demonstrates the nonrandom positioning of metaphase chromosomes bearing nucleolar organizer regions as revealed by their positive upstream binding factor immunolabeling. During the complex morphogenesis of the progeny nuclei from anaphase to late telophase, the equal partitioning of the nucleolar organizer regions is demonstrated by quantification, and their typical nonrandom central positioning within the chromosome sets is revealed.
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Gao, X. P., and J. Y. Li. "Nuclear division in the marine dinoflagellate Oxyrrhis marina." Journal of Cell Science 85, no. 1 (1986): 161–75. http://dx.doi.org/10.1242/jcs.85.1.161.
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The nuclear division of Oxyrrhis marina is a very distinct one among the mitoses of dinoflagellates that have been studies. Using synchronized populations, we have investigated the ultrastructural changes in this nuclear division. In interphase, nuclei can be classified into two groups on the basis of the shapes of the chromosomes. Y- and U-shaped chromosomes have been observed in both types of interphase nuclei. By prophase the nucleus becomes oval, many nuclear plaques appear on the nuclear envelope, and many microtubules radiate from these nuclear plaques within the nucleus. Metaphase can be identified by the characteristic arrangement of the chromosomes; an equatorial metaphase plate is absent. As in many higher organisms, anaphase includes two stages: anaphase A and anaphase B. During anaphase A the nucleus does not apparently elongate and the chromosomes migrate towards the poles by a combination of the shortening of the chromosome-associated microtubules and the elongation of those located between daughter chromosomes. During anaphase B the nucleus elongates to about twice its former length. This elongation may result from growth of the interzonal nuclear envelope. Dividing nucleoli are associated with microtubules, which suggests that microtubules may play an active role in the division of the nucleolus. The evolution of mitosis and the phylogenetic relationships between Oxyrrhis, typical dinoflagellates and Syndinium are discussed.
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Hiraoka, Y., D. A. Agard, and J. W. Sedat. "Temporal and spatial coordination of chromosome movement, spindle formation, and nuclear envelope breakdown during prometaphase in Drosophila melanogaster embryos." Journal of Cell Biology 111, no. 6 (1990): 2815–28. http://dx.doi.org/10.1083/jcb.111.6.2815.
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The spatial and temporal dynamics of diploid chromosome organization, microtubule arrangement, and the state of the nuclear envelope have been analyzed in syncytial blastoderm embryos of Drosophila melanogaster during the transition from prophase to metaphase, by three-dimensional optical sectioning microscopy. Time-lapse, three-dimensional data recorded in living embryos revealed that congression of chromosomes (the process whereby chromosomes move to form the metaphase plate) at prometaphase occurs as a wave, starting at the top of the nucleus near the embryo surface and proceeding through the nucleus to the bottom. The time-lapse analysis was augmented by a high-resolution analysis of fixed embryos where it was possible to unambiguously trace the three-dimensional paths of individual chromosomes. In prophase, the centromeres were found to be clustered at the top of the nucleus while the telomeres were situated at the bottom of the nucleus or towards the embryo interior. This polarized centromere-telomere orientation, perpendicular to the embryo surface, was preserved during the process of prometaphase chromosome congression. Correspondingly, breakdown of the nuclear envelope started at the top of the nucleus with the mitotic spindle being formed at the positions of the partial breakdown of the nuclear envelope. Our observation provide an example in which nuclear structures are spatially organized and their functions are locally and coordinately controlled in three dimensions.
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Tarkowska, J. A. "Endoplasmic reticulum hypertrophy and nuclear envelope formation - a. postulate." Acta Societatis Botanicorum Poloniae 48, no. 3 (2015): 381–89. http://dx.doi.org/10.5586/asbp.1979.032.
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Dividing endosperm cells of <i>Haemanthus katherinae</i> Bak., treated with 0.025 per cent aqueous solution of a mixture of glycosides from <i>Nerium oleander</i> were examined in vitro in the light and in the electron microscope. A high hypertrophy of endoplasmic reticulum was noted. In prometaphase and metaphase, after treatment for about l h 45 min there appeared very narrow cisternae forming various configurations, frequently in parallel and concentric arrangement. On the membranes of these cisternae there are formed dark areas interpreted as pores characteristic for nuclear envelopes, this indicating that at least part of the two-membrane structures transforms to the nuclear envelope. The formation of the new nuclear envelope pre-maturely and apparently in excess is discussed.
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Trask, Barbara J. F., Hillary Massa, Cynthia Friedman, Richard Esposito, Ger van den Engh, and Hiroki Yokota. "Use of fluorescence in situ hybridization to study the arrangement of DNA sequences in normal and disease-related chromosomes." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 748–49. http://dx.doi.org/10.1017/s0424820100140117.
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The sites of specific DNA sequences can be fluorescently tagged by fluorescence in situ hybridization (FISH). Different sequences can be labeled with different fluorochromes so that their arrangement can be studied using epifluorescence microscopy. The distances between points on the same or different chromosomes can be determined easily in a large number of interphase nuclei or metaphase chromosomes. A variety of probe types, ranging from single-copy sequences to highly repeated sequences can be employed. Our work has focussed on the analysis of hybridization patterns in two dimensions using conventional fluorescence microscopy.We have used FISH to study various aspects of genome organization that are difficult to study using other techniques. Examples of these applications will be presented.FISH is now the method of choice for determining the chromosomal location of DNA sequences. DNA sequences can be positioned in the genome with <1:1000 accuracy (to a 3-Mbp region within a 3000-Mbp genome). Through FISH, the cytogenetic, physical and genetic maps of chromosomes can be linked.
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Figueiras, Ana M., Maria T. Gonzalez-Jaen, Julio Salinas, and Cesar Benito. "ASSOCIATION OF ISOZYMES WITH A RECIPROCAL TRANSLOCATION IN CULTIVATED RYE (SECALE CEREALE L.)." Genetics 109, no. 1 (1985): 177–93. http://dx.doi.org/10.1093/genetics/109.1.177.
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ABSTRACT In rye (Secale cereale L. cv. "Ailés") the progeny of a cross between a structural heterozygote for a reciprocal translocation (involving the 1R chromosome) and a homozygote for the standard chromosome arrangement were analyzed for the electrophoretic patterns of eight different leaf isozymes and also for their meiotic configuration at metaphase I.—The Got-3 and Mdh-2b loci are linked to each other and also to the reciprocal translocation. The Mdh-2b locus is located in the interstitial segment of the 3Rq chromosome arm, with an estimated distance of 8 cM to the breakpoint. Therefore, the reciprocal translocation involves the 1R and 3R chromosomes.—Also, the Mdh-1 and 6-Pgd-2 loci are linked (16 ± 3 cM) and have been located on the 2Rq arm. Finally, the Per-3 and Per-4 loci are located on the 2Rp chromosome arm at an estimated distance of 26 ± 4 cM.
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Dobson, M. J., R. E. Pearlman, A. Karaiskakis, B. Spyropoulos, and P. B. Moens. "Synaptonemal complex proteins: occurrence, epitope mapping and chromosome disjunction." Journal of Cell Science 107, no. 10 (1994): 2749–60. http://dx.doi.org/10.1242/jcs.107.10.2749.
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We have used polyclonal antibodies against fusion proteins produced from cDNA fragments of a meiotic chromosome core protein, Cor1, and a protein present only in the synapsed portions of the cores, Syn1, to detect the occurrence and the locations of these proteins in rodent meiotic prophase chromosomes. The 234 amino acid Cor1 protein is present in early unpaired cores, in the lateral domains of the synaptonemal complex and in the chromosome cores when they separate at diplotene. A novel observation showed the presence of Cor1 axial to the metaphase I chromosomes and substantial amounts of Cor1 in association with pairs of sister centromeres. The centromere-associated Cor1 protein becomes dissociated from the centromeres at anaphase II and it is not found in mitotic metaphase centromeres. The extended presence of Cor1 suggests that it may have a role in chromosome disjunction by fastening chiasmata at metaphase I and by joining sister kinetochores, which ensures co-segregation at anaphase I. Two-colour immunofluorescence of Cor1 and Syn1 demonstrates that synapsis between homologous cores is initiated at few sites but advances rapidly relative to the establishment of new initiation sites. If the rapid advance of synapsis deters additional initiation sites between pairs of homologues, it may provide a mechanism for positive recombination interference. Immunogold epitope mapping of antibodies to four Syn1 fusion proteins places the amino terminus of Syn1 towards the centre of the synaptonemal complex while the carboxyl terminus extends well into the lateral domain of the synaptonemal complex. The Syn1 fusion proteins have a non-specific DNA binding capacity. Immunogold labelling of Cor1 antigens indicates that the lateral domain of the synaptonemal complex is about twice as wide as the apparent width of lateral elements when stained with electron-dense metal ions. Electron microscopy of shadow-cast surface-spread SCs confirms the greater width of the lateral domain. The implication of these dimensions is that the proteins that comprise the synaptic domain overlap with the protein constituents of the lateral domains of the synaptonemal complex more than was apparent from earlier observations. This arrangement suggests that direct interactions might be expected between some of the synaptonemal complex proteins.
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Girka, E., and K. R. Bondioli. "25 Effect of taxol and epothilone B on meiotic spindle stabilization in vitrified bovine oocytes." Reproduction, Fertility and Development 33, no. 2 (2021): 120. http://dx.doi.org/10.1071/rdv33n2ab25.
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Vitrification has the potential to be a valuable technique for preservation of bovine oocytes; however, this method often results in abnormal microtubule and chromosome arrangement. The aim of this experiment was to evaluate taxol and epothilone B as meiotic spindle stabilising pretreatments in a vitrification protocol. Bovine oocytes were purchased and matured invitro during shipment. At 18h of maturation, oocytes were divided randomly into control, taxol, and epothilone B treatments (Table 1). All treatments were prepared in invitro maturation (IVM) medium (IVF Biosciences). Partially denuded oocytes were incubated in either control or treatment medium for 15min at 38.5°C before vitrification. Oocytes were incubated in an equilibration solution (10% dimethyl sulfoxide, 10% ethylene glycol) for 5min, transferred to a vitrification solution (20% dimethyl sulfoxide, 20% ethylene glycol, 0.5M sucrose), loaded onto a Cryolock, and plunged into liquid nitrogen within 45s. For warming, a Cryolock was placed directly into a 0.5M sucrose solution and incubated for 3min. Oocytes were transferred to a 0.25M solution for 3min and washed in the basal solution used for vitrification and warming media (Dulbecco’s phosphate-buffered saline, 20% fetal bovine serum). Once warmed, oocytes were transferred to IVM medium for a 4-h recovery period and completely denuded before staining. Staining to evaluate spindle morphology was performed with anti α-tubulin primary antibody and secondary antibody Alexa Fluor 488. Oocytes were also stained with Hoechst to evaluate chromosome arrangement. Both spindle morphology and chromosome arrangement data were analysed using a logistic regression with a binomial response variable (normal/abnormal). Both 0.5μM and 1.0μM Taxol treatments had no effect on either meiotic spindle or chromosome arrangement compared with the control group (P&gt;0.05). The 2.0μM taxol treatment improved chromosome configuration (P&lt;0.05) with no effect on microtubule distribution compared with the control group (P&gt;0.05). All epothilone B treatments resulted in disruption of microtubule distribution and chromosome arrangement compared with control (P&lt;0.001) and resulted in a consistent abnormality hypothesised to be tubulin polymerization. These results indicate that taxol is capable of increasing the occurrence of normal chromosome arrangement in vitrified bovine oocytes and that epothilone B may cause additional harm to the oocyte that is not associated with the metaphase plate. Table 1. Effect of stabilisation agents on meiotic spindle of invitro-matured bovine oocytes Treatment n Normal microtubule distribution (%) Normal chromosome arrangement (%) Control 100 44 47 0.5μM Taxol 104 44 37 1.0μM Taxol 98 43 56 2.0μM Taxol 102 49 62a 0.5μM Epothilone B 103 11b 11b 1.0μM Epothilone B 97 6b 8b 2.0μM Epothilone B 100 2b 1b aP&lt;0.05;. bP&lt;0.001: Different superscripts within a column indicate a significant difference.
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Girka, E., and K. R. Bondioli. "25 Effect of taxol and epothilone B on meiotic spindle stabilization in vitrified bovine oocytes." Reproduction, Fertility and Development 33, no. 2 (2021): 120. http://dx.doi.org/10.1071/rdv33n2ab25.
Full textAbstract:
Vitrification has the potential to be a valuable technique for preservation of bovine oocytes; however, this method often results in abnormal microtubule and chromosome arrangement. The aim of this experiment was to evaluate taxol and epothilone B as meiotic spindle stabilising pretreatments in a vitrification protocol. Bovine oocytes were purchased and matured invitro during shipment. At 18h of maturation, oocytes were divided randomly into control, taxol, and epothilone B treatments (Table 1). All treatments were prepared in invitro maturation (IVM) medium (IVF Biosciences). Partially denuded oocytes were incubated in either control or treatment medium for 15min at 38.5°C before vitrification. Oocytes were incubated in an equilibration solution (10% dimethyl sulfoxide, 10% ethylene glycol) for 5min, transferred to a vitrification solution (20% dimethyl sulfoxide, 20% ethylene glycol, 0.5M sucrose), loaded onto a Cryolock, and plunged into liquid nitrogen within 45s. For warming, a Cryolock was placed directly into a 0.5M sucrose solution and incubated for 3min. Oocytes were transferred to a 0.25M solution for 3min and washed in the basal solution used for vitrification and warming media (Dulbecco’s phosphate-buffered saline, 20% fetal bovine serum). Once warmed, oocytes were transferred to IVM medium for a 4-h recovery period and completely denuded before staining. Staining to evaluate spindle morphology was performed with anti α-tubulin primary antibody and secondary antibody Alexa Fluor 488. Oocytes were also stained with Hoechst to evaluate chromosome arrangement. Both spindle morphology and chromosome arrangement data were analysed using a logistic regression with a binomial response variable (normal/abnormal). Both 0.5μM and 1.0μM Taxol treatments had no effect on either meiotic spindle or chromosome arrangement compared with the control group (P&gt;0.05). The 2.0μM taxol treatment improved chromosome configuration (P&lt;0.05) with no effect on microtubule distribution compared with the control group (P&gt;0.05). All epothilone B treatments resulted in disruption of microtubule distribution and chromosome arrangement compared with control (P&lt;0.001) and resulted in a consistent abnormality hypothesised to be tubulin polymerization. These results indicate that taxol is capable of increasing the occurrence of normal chromosome arrangement in vitrified bovine oocytes and that epothilone B may cause additional harm to the oocyte that is not associated with the metaphase plate. Table 1. Effect of stabilisation agents on meiotic spindle of invitro-matured bovine oocytes Treatment n Normal microtubule distribution (%) Normal chromosome arrangement (%) Control 100 44 47 0.5μM Taxol 104 44 37 1.0μM Taxol 98 43 56 2.0μM Taxol 102 49 62a 0.5μM Epothilone B 103 11b 11b 1.0μM Epothilone B 97 6b 8b 2.0μM Epothilone B 100 2b 1b aP&lt;0.05;. bP&lt;0.001: Different superscripts within a column indicate a significant difference.
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Somfai, T., K. Kikuchi, J. Noguchi, et al. "318 INHIBITION OF FIRST POLAR BODY EXTRUSION BY CYTOCHALASIN B DURING IN VITRO MATURATION OF PORCINE OOCYTES LEADS TO RE-ARRANGEMENT OF THE SEGREGATED CHROMOSOMES AND IMPROVEMENT IN THE QUALITY OF THE PARTHENOGENETIC BLASTOCYSTS." Reproduction, Fertility and Development 18, no. 2 (2006): 266. http://dx.doi.org/10.1071/rdv18n2ab318.
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Diploid parthenotes are usually obtained by the inhibition of second polar body (PB2) extrusion after activation of metaphase II (MII) oocytes. However, diploid embryos can be generated by the inhibition of the first polar body (PB1) extrusion as well, using cytochalasin B (CB) during in vitro maturation prior the activation procedure. A higher percentage of mouse embryos generated by the activation of MII oocytes and the inhibition of PB2 extrusion were proven to be homozygous than for parthenotes obtained by the latter method (Kubiak et al. 1991 Development 111, 763-769). The aim of the present study was to examine if such difference has any effect on the development of parthenogenetic embryos in vitro. Nuclear progression and in vitro embryonic development after parthenogenetic activation of porcine oocytes exposed to CB during in vitro maturation (IVM) was investigated in the present study. The tendency of nuclear maturation was similar in oocytes matured in the presence of 1 �g/mL CB (IVM-CB group) and control oocytes matured without CB after 37 h of IVM; at this time the frequency of oocytes that had reached/or passed through anaphase-I stage did not differ significantly (P < 0.05) between the IVM-CB and the control groups (61.3% and 69.9%, respectively), however, no polar body extrusion was observed in the IVM-CB group and the two lumps of homologue chromosomes remained in the oocyte and turned into two irregular sets of condensed chromosomes. By 41 h of IVM, the double sets of chromosomes re-united in 89.5% of IVM-CB oocytes and formed a single large metaphase plate, whereas 68.8% of the control oocytes had reached metaphase-II stage (MII) by this time. When IVM-CB oocytes were electrically (1.5 kV/cm for 100 �s) activated and subsequently cultured without CB, 39% of the oocytes extruded a polar body (PB) and 82.9% of them had a female pronucleus. When those oocytes with PB were cultured, the blastocyst rate of the cleaved embryos did not differ (P < 0.05) from those of the control that were stimulated at MII and subsequently treated with CB (43.3% and 48.2%, respectively). The number of blastomeres in Day 6 blastocysts was significantly higher (P < 0.05) in the IVM-CB derived embryos than in those in the control group (47.8 and 40.7, respectively); moreover, the ratio of dead blastomeres (dead cells : live cells) was higher (P < 0.05) in the control than in the IVM-CB blastocysts (0.047 and 0.031, respectively). A possible explanation for this result might be a lower frequency of homozygous genes in IVM-CB parthenotes, in which segregation of sister chromatids were promoted instead of segregation of homologous chromosomes to obtain diploid embryos. In such embryos the expression of recessive lethal, sublethal and subvital genes might have a lower probability. This work was supported by the Japanese-Hungarian bilateral scientific and technological cooperation (TET JAP-11/02).
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Oud, J. L., A. Mans, G. J. Brakenhoff, H. T. van Der Voort, E. A. van Spronsen, and N. Nanninga. "Three-dimensional chromosome arrangement of Crepis capillaris in mitotic prophase and anaphase as studied by confocal scanning laser microscopy." Journal of Cell Science 92, no. 3 (1989): 329–39. http://dx.doi.org/10.1242/jcs.92.3.329.
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To estimate the extent of ordering of chromosomes, confocal scanning laser microscopy was used to make three-dimensional images from optical sections. For Crepis capillaris, which has 2n = 6 easily recognizable chromosomes, a statistically significant sample of 75 Feulgen-stained root tip anaphases was analysed. A comparison of the observed chromosome ordering and the expected random distribution showed a significant surplus of one of the arrangements with a juxtaposition of the two chromosomes with a nucleolus organizer region. Two of the arrangements with these chromosomes in opposite positions were never observed in our material. Another analysis of 30 mithramycin A-stained prophases and 30 meta- and anaphases showed partly different patterns of non-random chromosome distribution in the two stages of mitosis. A preference for an association of the homologues was observed for all pairs of chromosomes in prophase cells, whereas in meta- and anaphase the association only persisted for the nucleolus organizer chromosomes. This indicates that there may be some relocation of the chromosome positions during the transition from prophase to metaphase. In meta- and anaphase one of the arrangements with juxtaposed NOR chromosomes was preferred, i.e. the ordering in which chromosomes 1 and 3 occupied alternate positions. Probably, the nucleolus is an important factor in producing a non-random distribution, but there could be other factors that influence chromosome ordering as well. A comparison of the anaphase chromosome ordering in C. capillaris plants from very different localities, indicated that the observed non-random distribution was independent of the origin of the material. Existing models of chromosome disposition are not sufficient to explain the observed non-random chromosome ordering in C. capillaris.
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Idowu, A. B., and O. A. Akinnusi. "The structure of the ovotestis of the common African land snails found in Abeokuta, South Western Nigeria." Nigerian Journal of Animal Production 33, no. 2 (2021): 286–93. http://dx.doi.org/10.51791/njap.v33i2.938.
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A comparative study of the structure of the ovotestis of African land snails found in Abeokuta was investigated. Of all the five snails species found and dissected, Archachatina marginata, Achatina achatina, A. fulica, Helix pomatia and Limcolaria aurora, only the ovotestis of H. pomatia could not be observed. The positioning, shape and arrangement of the ovotestis was the same for all the other four species. The ovotestis is embedded in the digestive gland at the anterior region of the coiled posterior end of the visceral mass. It is cream coloured and made up of sac-like lobes arranged on a single plane. It is differentiated into an ovariaon and testicular region. The number and size of the ovotestis differ significantly (P<0.05) in all the snails. Each lobe is made of several follicles and the number of which varied in the four species. Statistical analysis showed that live weight, shell length, shell width and shell circumference of the snails had no significant influence on the size on their ovotestis. Meiotic metaphase spreads of the ovotestis tissues revealed chromosome numbers 2n=56, 2n=44, 2n=54 and 2n=28 for A. marginata, A. achatina, A. fulica and L. aurora
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Buchenau, P., H. Saumweber, and D. J. Arndt-Jovin. "Consequences of topoisomerase II inhibition in early embryogenesis of Drosophila revealed by in vivo confocal laser scanning microscopy." Journal of Cell Science 104, no. 4 (1993): 1175–85. http://dx.doi.org/10.1242/jcs.104.4.1175.
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The regulation of DNA topology by topoisomerase II from Drosophila melanogaster has been studied extensively by biochemical methods but little is known about its roles in vivo. We have performed experiments on the inhibition of topoisomerase II in living Drosophila blastoderm embryos. We show that the enzymatic activity can be specifically disrupted by microinjection of antitopoisomerase II antibodies as well as the epipodophyllotoxin VM26, a known inhibitor of topoisomerase II in vitro. By labeling the chromatin of live embryos with tetramethylrhodamine-coupled histones, the effects of inhibition on nuclear morphology and behaviour was followed in vivo using confocal laser scanning microscopy. Both the antibodies and the drug prevented or hindered the segregation of chromatin daughter sets at the anaphase stage of mitosis. In addition, high concentrations of inhibitor interfered with the condensation of chromatin and its proper arrangement into the metaphase plate. The observed effects yielded non-functional nuclei, which were drawn into the inner yolk mass of the embryo. Concurrently, undamaged nuclei surrounding the affected region underwent compensatory division, leading to the restoration of the nuclear population, and thereby demonstrating the regulative capacity of Drosophila blastoderm embryos.
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Kuhn, S., C. E. Vorgias, and P. Traub. "Interaction in vitro of non-epithelial intermediate filament proteins with supercoiled plasmid DNA." Journal of Cell Science 87, no. 4 (1987): 543–54. http://dx.doi.org/10.1242/jcs.87.4.543.
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Sucrose gradient analysis of reaction products obtained from non-epithelial intermediate filament (IF) subunit proteins and a mixture of supercoiled, relaxed and linearized plasmid pBR322 DNA at low ionic strength revealed that limited amounts of these polypeptides interacted exclusively with the supercoiled form of the plasmid DNA. These results were corroborated by electron-microscopic analysis of the reaction products, which showed that only circles of supercoiled pBR322 DNA were completely and smoothly covered with vimentin. IFs reconstituted from pure vimentin reacted with supercoiled pBR322 DNA only through their physical ends. The reaction of an aged preparation of vimentin with supercoiled pBR322 DNA produced large aggregates consisting of a central, axially oriented protein scaffold to which individual loops of DNA were attached at their bases in a halo-like arrangement. The electron-microscopic appearance of such complexes was very reminiscent of that of histone-depleted metaphase chromosomes. Together with the previous observations that non-epithelial IF proteins have high affinities for single-stranded DNA and core histones and that they are structurally and functionally closely related to the nuclear lamins, these results were used to advance a novel hypothesis on the biological role of IF proteins in eukaryotic cells.
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Kolarov, A. "Prostaglandin F2A Disturbs Oogenesis by Causing Meiotic Spindle Damage." Acta Medica Bulgarica 51, no. 4 (2024): 47–51. http://dx.doi.org/10.2478/amb-2024-0077.
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Abstract According to recent data, prostaglandin F2 alpha can have a negative influence on meiosis during oogenesis. Previously, we have found that this prostaglandin may accelerate in a dosage-dependent way the postovulatory aging in ovulated mature oocytes, compromising the integrity of their meiotic spindles. Aim. The study aimed to investigate the effects of prostaglandin F2α on the course and outcome of oocyte meiosis in a mouse model. Materials and Methods. Mouse oocytes were matured in vitro in the presence of prostaglandin F2α in a concentration of 100 ng/ml. Their meiotic stage, spindle morphology and chromosome arrangement were assessed by immunofluorescent labeling of tubulin and fluorescent staining of DNA. Results. We obtained a higher percentage of immature oocytes in metaphase I after the treatment than in untreated control oocytes. In addition, there were specific morphological changes in the meiotic spindles of oocytes exposed to prostaglandin F2α associated with a reduced number of fibers. Conclusion. It is probable that prostaglandin F2α has an impact on the microtubule dynamics of the meiotic spindle that can prevent the transition of maturing oocytes to the second meiotic division, most likely by triggering the spindle assembly checkpoint.
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Howard-Till, Rachel, and Josef Loidl. "Condensins promote chromosome individualization and segregation during mitosis, meiosis, and amitosis in Tetrahymena thermophila." Molecular Biology of the Cell 29, no. 4 (2018): 466–78. http://dx.doi.org/10.1091/mbc.e17-07-0451.
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Condensin is a protein complex with diverse functions in chromatin packaging and chromosome condensation and segregation. We studied condensin in the evolutionarily distant protist model Tetrahymena, which features noncanonical nuclear organization and divisions. In Tetrahymena, the germline and soma are partitioned into two different nuclei within a single cell. Consistent with their functional specializations in sexual reproduction and gene expression, condensins of the germline nucleus and the polyploid somatic nucleus are composed of different subunits. Mitosis and meiosis of the germline nucleus and amitotic division of the somatic nucleus are all dependent on condensins. In condensin-depleted cells, a chromosome condensation defect was most striking at meiotic metaphase, when Tetrahymena chromosomes are normally most densely packaged. Live imaging of meiotic divisions in condensin-depleted cells showed repeated nuclear stretching and contraction as the chromosomes failed to separate. Condensin depletion also fundamentally altered chromosome arrangement in the polyploid somatic nucleus: multiple copies of homologous chromosomes tended to cluster, consistent with a previous model of condensin suppressing default somatic pairing. We propose that failure to form discrete chromosome territories is the common cause of the defects observed in the absence of condensins.
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Singh, R. J., and T. Tsuchiya. "Cytogenetics of two novel compensating diploids in barley (Hordeum vulgare)." Genome 36, no. 2 (1993): 343–49. http://dx.doi.org/10.1139/g93-047.
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Novel compensating diploid plants are very rare in diploid species. The objective of this study was to describe the origin, identification, and meiotic and breeding behaviors of two compensating diploids of barley (Hordeum vulgare L.), isolated in a spring-type two-rowed cultivar, 'Shin Ebisu 16' (SE 16). A plant with 2n = 13 + 1 acro3L3S + 1 telo3S was identified cytologically in an F2 population from the cross 2n = 14 + 1 acro3L3S × yst 2 (yellow streak 2). In this plant, 1 acro3L3S and 1 telo3S compensated for one normal chromosome 3. The selfed population from this plant usually segregated three chromosomal types in a ratio of 1 (2n = 14): 2 (2n = 13 + 1 acro3L3S + 1 telo3S): (2n = 12 + 2 acro3L3S + 2 telo3S). A 1 (2n = 14): 1 (2n = 13 + 1 acro3L3S + 1 telo3S) ratio was observed when the plants with 2n = 13 + 1 acro3L3S + 1 telo3S were crossed with a diploid either as a male or female. At metaphase I, plants with 2n = 13 + 1 acro3L3S + 1 telo3S showed a 1 III + 6 II configuration in 84% of the sporotypes and the remaining (16%) sporocytes had a 6 II + I 11 (heteromorphic) + 1 I configuration. The chromosome arrangement in a trivalent was ∙3S–3S∙3L–3L3S. At anaphase I, a 7–8 (6 + 1 acro3L3S + 1 telo3S) chromosome separation was observed in 87.9% sporocytes. The second compensating diploid (2n = 12 + 2 acro3L3S + 2 telo3S) bred true and only produced plants with 2n = 13 + 1 acro3L3S + 1 telo3S when crossed with a diploid either as a male or female. At metaphase I, 97% of the sporocytes showed 8 II (6 II + I acro3L3S II + 1 telo3SII) and an 8–8 chromosome separation was recorded in 90% of the sporocytes at anaphase I. Morphologically, plants with 2n = 14, 2n = 13 + 1 acro3L3s + 1 telo3S, and 2n = 12 + 2 acro3L3S + 2 telo3S were indistinguishable.Key words: acrotrisomics, telotrisomics, heterochromatin.
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Gilbert, N., L. Lucas, C. Klein, M. Menager, N. Bonnet, and D. Ploton. "Three-dimensional co-location of RNA polymerase I and DNA during interphase and mitosis by confocal microscopy." Journal of Cell Science 108, no. 1 (1995): 115–25. http://dx.doi.org/10.1242/jcs.108.1.115.
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The relative three-dimensional co-location of RNA polymerase I (RPI) and DNA was studied using confocal laser scanning microscopy during interphase and all the steps of mitosis in human cancerous cells. For each step of the cell cycle, immunolabeled RPI molecules and DNA specifically stained with chromomycin A3 were simultaneously imaged at high resolution through numerous optical sections. Then, all the data obtained were used to generate transverse sections, anaglyphs and volumic representations, which are all prerequisite approaches to a representative study of the three-dimensional organization of the nucleolus and the mitotic chromosomes. Our results indicated that in the interphasic nuclei, in which DNA is organized as a regular 3-D network, RPI was present within numerous irregular spheres arranged as several twisted necklaces. During metaphase, RPI labeling was segregated into pairs of spheres and typical crescent-shaped structures; both were centrally located within the set of chromosomes. During anaphase and telophase, a typical central and symmetric arrangement of labeled structures was systematically seen among the decondensing chromosomes, arranged as a regular cylinder and as a hollow half-sphere, respectively. This typical 3-D organization of structures containing RPI relative to DNA is another strong example of the non-random organization of the genome during interphase and mitosis.
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Andreassen, P. R., and R. L. Margolis. "Induction of partial mitosis in BHK cells by 2-aminopurine." Journal of Cell Science 100, no. 2 (1991): 299–310. http://dx.doi.org/10.1242/jcs.100.2.299.
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The protein kinase inhibitor 2-aminopurine (2-AP) inhibits a subset of mitotic events in BHK cells. In the presence of the drug, these cells form a bipolar spindle in mitosis, but chromatin fails to generate functioning chromosomes. Cells in 2-AP progress through a partial mitosis, in which there is no observable metaphase, anaphase or telophase events. After 12 h of exposure to 2-AP the chromatin in mitotic cells fails to condense into discrete chromosomes, and is displaced by the spindle to form ‘binucleate’ cells and cells containing abnormally shaped nuclei in the subsequent interphase. Other mitotic modifications of nuclei, such as nucleolar and nuclear lamina disassembly, occur normally. Centromeres in these nuclei do not become engaged in the spindle, but instead show either no association or a lateral arrangement around the spindle. Cells treated with 2-AP are not arrested in mitosis. Therefore, mitotic exit is not inhibited by the failure of these cells to progress through the latter stages of mitosis. Further, nocodazole-arrested cells quickly exit mitotic arrest when 2-AP is added. We conclude that 2-AP interferes with a specific subset of mitotic events, and that it allows cells to overcome check-points that require spindle function for mitotic progression.
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Abdelkader, A. G., W. H. Mohamed, M. Abou-Ellail, and K. A. Amein. "Reproductive and genotoxic effects of dinotefuran in male Sprague Dawley rats." BULGARIAN JOURNAL OF VETERINARY MEDICINE 28, no. 1 (2025): 42–54. https://doi.org/10.15547/bjvm.2023-0062.
Full textAbstract:
The objective of the current study was the evaluation of the genotoxic and reproductive effects of dinotefuran (DIN) insecticide in male Sprague Dawley rats. To achieve these objectives, forty male 10–12 weeks old Sprague Dawley rats were randomly divided into four equal groups; the first group was used as a control group; the other three groups were exposed to 40, 61, and 122 mg/kg body weight DIN by oral gavage for 8 weeks. Relative testicular weight, testosterone, follicle stimulating hormone (FSH), luteinizing hormone (LH), malondialdehyde (MDA) and glutathione peroxidase (GPx) levels, sperm viability, sperm morphology, chromosomal aberrations assay, expression of interleukin 6 (IL-6) and cluster of differentiation 68 (CD68), and histopathological changes in testes of these rats were examined after 8 weeks. The results showed that DIN exposure resulted in a significant increase in testosterone, the percentage of dead and abnormal sperms, the percentage of metaphase cells with chromosomal aberrations, and expression of IL-6 and CD-68 but decreased GPx levels. Histopathological examination of the testes revealed hypertrophied seminiferous tubules of testes with a disrupted arrangement of germinal epithelial cells accompanied by many necrotic areas. It was concluded that exposure to DIN for 8 weeks induced hazardous impacts on the reproductive system and caused genotoxicity.
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McDonald, K. L., E. T. O'Toole, D. N. Mastronarde, and J. R. McIntosh. "Kinetochore microtubules in PTK cells." Journal of Cell Biology 118, no. 2 (1992): 369–83. http://dx.doi.org/10.1083/jcb.118.2.369.
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We have analyzed the fine structure of 10 chromosomal fibers from mitotic spindles of PtK1 cells in metaphase and anaphase, using electron microscopy of serial thin sections and computer image processing to follow the trajectories of the component microtubules (MTs) in three dimensions. Most of the kinetochore MTs ran from their kinetochore to the vicinity of the pole, retaining a clustered arrangement over their entire length. This MT bundle was invaded by large numbers of other MTs that were not associated with kinetochores. The invading MTs frequently came close to the kinetochore MTs, but a two-dimensional analysis of neighbor density failed to identify any characteristic spacing between the two MT classes. Unlike the results from neighbor density analyses of interzone MTs, the distributions of spacings between kinetochore MTs and other spindle MTs revealed no evidence for strong MT-MT interactions. A three-dimensional analysis of distances of closest approach between kinetochore MTs and other spindle MTs has, however, shown that the most common distances of closest approach were 30-50 nm, suggesting a weak interaction between kinetochore MTs and their neighbors. The data support the ideas that kinetochore MTs form a mechanical connection between the kinetochore and the pericentriolar material that defines the pole, but that the mechanical interactions between kinetochore MTs and other spindle MTs are weak.
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McIntosh, J. R., U. P. Roos, B. Neighbors, and K. L. McDonald. "Architecture of the microtubule component of mitotic spindles from Dictyostelium discoideum." Journal of Cell Science 75, no. 1 (1985): 93–129. http://dx.doi.org/10.1242/jcs.75.1.93.
Full textAbstract:
Ten mitotic spindles from Dictyostelium discoideum have been studied by electron microscopy of serial sections. We have used computer graphics to track individual microtubules (MTs) in three dimensions and to compare seven spindles at different stages of anaphase and telophase. The central spindle of early anaphase is formed by the interdigitation of two sets of pole-associated MTs. The distribution of MT lengths at this stage is hetero-disperse. During anaphase total MT length decreases by a factor of about 2 as a result of two opposing changes in MT length: the longer MTs that interdigitate become even longer, while the short MTs, including those attached to kinetochores, become shorter still and decrease in number. The extent of MT interdigitation is less in longer spindles than in short ones. In metaphase and early anaphase, the MTs are not in an ordered arrangement as seen in spindle cross-sections, but as anaphase proceeds the MTs cluster into a square-packed, paracrystalline bundle in which most of the nearest neighbours come from opposite poles. This arrangement and the condensation-like increase in order suggest the existence of specific interactions between antiparallel MTs. A quantitative analysis of MT positions supports this interpretation, but direct evidence for convincing bridges between MTs is lacking. The pole-distal ends of the MTs that interdigitate show an irregular termination (C-shaped ends in transverse view), as is characteristic of MTs that are either adding or losing subunits. Since it is these interdigitating MTs that elongate, and since the shortening MTs show the customary blunt endings, we conclude that subunits add to the interdigitating MTs at their pole-distal ends. This inference, combined with other structural data, suggests that the interdigitating MTs of Dictyostelium are sliding over one another as they polymerize in anaphase. It also suggests a simple model for why the spindle becomes thinner as it elongates. We propose that MT interdigitation defines a region where MTs bind a factor that will associate only with antiparallel MTs. This factor biases the MT assembly equilibrium toward polymer. As the shorter MTs slide out of this region, they lose their polymerization advantage and depolymerize, releasing subunits to contribute to the further elongation of the already longer MTs. The properties of the Dictyostelium spindle are compared with those of both higher and lower eukaryotes.
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Sánchez-Toranzo, G., J. Zapata-Martínez, C. Catalán, and M. I. Bühler. "Effect of different types of sesquiterpene lactones on the maturation of Rhinella arenarum oocytes." Zygote 23, no. 3 (2014): 406–11. http://dx.doi.org/10.1017/s0967199413000695.
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SummaryThe sesquiterpene lactones (STLs) are a large class of plant secondary metabolites that are generally found in the Asteraceae family and that have high diversity with respect to chemical structure as well as biological activity. STLs have been classified into different groups, such as guaianolides, germacranolides, and melampolides etc., based on their carboxylic skeleton. In amphibians, fully grown ovarian oocytes are arrested at the beginning of meiosis I. Under the stimulus of progesterone, this meiotic arrest is released and meiosis progresses to metaphase II, a process known as oocyte maturation. The purpose of this work was to determine whether sesquiterpene lactones from the germacranolide and melampolide groups act as inhibitor agents on the meiosis of amphibian oocytes in vitro. Results for germacranolides indicated that the addition of deoxyelephantopins caused a high degree of inhibition and that minimolide showed a moderate inhibitory effect, whereas glaucolide A was inactive. Furthermore, the addition of melampolides (uvedalin, enhydrin, polymatin A and polymatin B) showed inhibitory effects. For enhydrin and uvedalin, inhibitory effects were observed at the higher concentrations assayed. The results of this study suggest that the inhibitory activity of the tested sesquiterpene lactones on the meiosis of Rhinella arenarum oocytes is not dependent on the group to which they belong, i.e. not on the carboxylic skeleton, but probably due to the arrangement and type of function groups present in the molecules. All assayed lactones in the germacranolide group showed low toxicity. In contrast, important differences in toxicity were observed for lactones from the melampolide group: enhydrin and uvedalin showed low toxicity, but polymatin A and B were highly toxic.
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Gutierrez, E. J., F. A. Diaz, B. A. Foster, and K. R. Bondioli. "48 Effect of Dimethyl Sulfoxide- or Glycerol-Based Vitrification Protocols on Meiotic Spindle of In Vitro-Matured Bovine Oocytes." Reproduction, Fertility and Development 30, no. 1 (2018): 163. http://dx.doi.org/10.1071/rdv30n1ab48.
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There is evidence suggesting that high concentrations of cryoprotectants (CPA) and very low temperatures during vitrification cause disruption of the meiotic spindle, resulting in poor post-warming meiotic resumption and other abnormalities at fertilization. This study sought to determine the damage caused by CPA and freezing upon the meiotic spindle of bovine oocytes vitrified at the metaphase II stage, and whether a subsequent incubation could promote recovery from this damage. Bovine cumulus–oocyte complexes were purchased from a commercial vendor (n = 154). Oocytes were removed from in vitro maturation media at 22 h, denuded by vortexing in hyaluronidase, and divided into 4 groups according to CPA exposure and whether they were incubated or not. The resulting groups were DMSO I (n = 36), DMSO NI (n = 41), GLY I (n = 39), GLY NI (n = 38). Two repetitions were carried out for each protocol evaluated, which included a combination of ethylene glycol (EG) with either dimethyl sulfoxide (DMSO) or glycerol (GLY). Oocytes were exposed to equilibration solution consisting of 7.5% EG and 7.5% DMSO or GLY for 9 min at room temperature (RT) and then placed into vitrification solution (VS) that contained 15% EG, 15% DMSO or GLY, and 0.5 M sucrose. While in VS, 3 to 4 denuded oocytes were loaded onto a Cryolock® (Biotech Inc., Alpharetta, GA, USA) and plunged into liquid nitrogen within 1 min. For warming, oocytes were exposed to previously warmed (37°C) dilution solution 1 (DS1) consisting of 0.5 M sucrose for 1 and 2 min at RT, for a total of 3 min in DS1, and then placed in dilution solution 2 containing 0.25 M sucrose for 3 min. Finally, oocytes were washed in base media. Base media for all solutions was PBS supplemented with 20% fetal bovine serum. After warming, half of the oocytes were fixed and the rest were submitted to a 2-h incubation period in maturation media at 37°C and 5.5% CO2, and then fixed. To examine microtubule distribution and chromosome arrangement, fixed oocytes were submitted to an immunofluorescence protocol using α-tubulin antibody (1:100) as primary antibody, Alexa Fluor 488 (1:1000) as secondary antibody, and counterstained with propidium iodide (10 mg mL−1). Oocytes were observed under a fluorescence microscope. The effects of CPA and incubation on the incidence of abnormal spindles measured with both microtubules distribution and chromosome arrangement were evaluated using logistic regression with a binomial response variable (normal/abnormal). For microtubule distribution, results showed that oocytes treated with DMSO presented significantly lower normality (31.17%) than those treated with glycerol (54.55%; P < 0.003). The most common abnormality observed in oocytes treated with DMSO was that the spindle was smaller and more faintly stained than those treated with glycerol. For chromosome arrangement, there was no significant difference between treatments (P = 0.7093). Additionally, there was no sign of improvement when submitting the oocytes to an incubation period for any of the components examined.
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Yi, Zi-Yun, Qiu-Xia Liang, Qian Zhou, et al. "Maternal total sleep deprivation causes oxidative stress and mitochondrial dysfunction in oocytes associated with fertility decline in mice." PLOS ONE 19, no. 10 (2024): e0306152. http://dx.doi.org/10.1371/journal.pone.0306152.
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Previous studies have shown sleep deprivation is increasingly reported as one of the causes of female infertility. However, how and by what relevant mechanisms it affects female fertility remains unclear. In this study, female mice underwent 72 hours of total sleep deprivation (TSD) caused by rotating wheel or 2 different controls: a stationary wheel, or forced movement at night. Even though, there was no significant difference in the number of eggs ovulated by the TSD mice compared to the control groups. Overall levels of estrogen and FSH were lower throughout the estrus cycle. A total of 42 genes showed significant differential expression in GV oocytes after TSD by RNA sequencing (RNA-Seq). These included genes were enriched in gene ontology terms of mitochondrial protein complex, oxidoreductase activity, cell division, cell cycle G1/S phase transition, as well as others. The increased concentrations of reactive oxygen species (ROS) in germinal vesicle (GV) and metaphase II (MII) oocytes from TSD mice were observed, which might be induced by impaired mitochondrial function caused by TSD. The GV oocytes displayed increased mitochondrial DNA (mtDNA) copy number and a significant transient increase in inner mitochondrial membrane potential (Δψm) from the TSD mice probably due to compensatory effect. In contrast, MII oocytes in the TSD group showed a decrease in the mtDNA copy number and a lower Δψm compared with the controls. Furthermore, abnormal distribution of mitochondria in the GV and MII oocytes was also observed in TSD mice, suggesting mitochondrial dysfunction. In addition, abnormal spindle and abnormal arrangement of chromosomes in MII oocytes were markedly increased in the TSD mice compared with the control mice. In conclusion, our results suggest that TSD significantly alters the oocyte transcriptome, contributing to oxidative stress and disrupted mitochondrial function, which then resulted in oocyte defects and impaired early embryo development in female mice.
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Marciano, Tal, Shay Levi, and Zeev Bomzon. "NIMG-58. THE EFFECT OF CELL CONFLUENCE ON THE DISTRIBUTION OF TUMOR TREATING FIELDS." Neuro-Oncology 22, Supplement_2 (2020): ii161. http://dx.doi.org/10.1093/neuonc/noaa215.671.
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Abstract BACKGROUND Tumor Treating Fields (TTFields) are known to exert anti-mitotic effects on cells. Numerical simulations investigating the electric field distribution within isolated cells have been reported. These studies have shown that during metaphase a uniform electric field forms within the rounded cells. This field is thought to disrupt spindle formation through alignment of the tubulin dimers with the field. Simulations also show that during cytokinesis, a non-uniform electric field forms at the furrow, leading to strong dielectrophoretic forces that further disrupt cell division. Cells in the tumor are densely packed. We used numerical simulations to investigate how the clustering of cells influences TTFields distribution. METHODS COMSOL was used to numerically simulate delivery of TTFields to clusters of round cells placed in a hexagonal arrangement. The influence of the distance between the cells on field distribution was investigated. The effect of pores in the cell membrane on field distribution was also investigated. RESULTS Placing round cells in clusters resulted in regions of highly non-uniform fields within the cells. Strong gradients in the electric field were also observed around pores placed in the membrane. Non-uniformity and gradients in the field could result in strong dielectrophoretic forces capable of disrupting key cellular structures such as the cytoskeleton and mitotic spindle, as well as cell membrane integrity. CONCLUSIONS The placement of cells in close proximity to one another creates gradients in the electric field, which could be associated with very strong dielectrophoretic forces that enhance the effects of TTFields on cells. Strong dielectrophoretic forces were also observed around the membrane pores. Previous studies have reported that TTFields increases membrane permeability [Chang et al Cell Death Discovery. 2018]. The strong dielectrophoretic forces in the membrane may provide a physical mechanism by which TTFields enhance membrane permeability.