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Fegaras-Arch E, Berns M, Forer A. Evidence of Non-microtubule Spindle Forces in Mesostoma ehrenbergii Spermatocytes. Front Mol Biosci 2020; 7:557990. [PMID: 33330616 PMCID: PMC7711074 DOI: 10.3389/fmolb.2020.557990] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 10/19/2020] [Indexed: 01/04/2023] Open
Abstract
We tested conclusions reached in previous experiments in which Mesostoma spermatocyte chromosomes moved rapidly to a pole in the absence of microtubules: after 10 μM nocodazole (NOC) depolymerized metaphase spindle microtubules, kinetochores from each of the 3 bivalents detached from the same pole and rapidly moved to the other pole, at speeds averaging 37.7 μm/min. with some as high as 100 μm/min. We concluded that these very fast movements were due to non-microtubule forces arising from a spindle matrix. However, since the chromosomes stretch out before detaching, there is tension in the chromosomes from the stretch. Thus the movements of detached kinetochores conceivably might be due to recoil from the tension, though we argued against this possibility (Fegaras and Forer, 2018a). In this article we test whether recoil causes the movements. We cut bivalents into 2 pieces, using a femtosecond laser, before addition of NOC. When 1 bivalent was severed, all kinetochores moved to one pole in 12/15 cells; when 2 bivalents were severed, all kinetochores moved to one pole in 4/6 cells; and when all 3 bivalents were severed all kinetochores moved to one pole in 3/9 cells. The bivalent “halves” moved rapidly, with average speeds of 47 μm/min, velocities that are not significantly different from those in cells without any laser-cut bivalents (p > 0.05). Since kinetochores move at the same speeds whether they are part of bivalents or not, NOC-induced chromosome movements are not due to recoil from tension along the full-length bivalent, strongly supporting the idea that non-microtubule forces move chromosomes in Mesostoma spermatocytes.
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Affiliation(s)
| | - Michael Berns
- Departments of Biomedical Engineering and Cell Biology, Beckman Laser Institute, University of California, Irvine, Irvine, CA, United States.,Institute for Engineering in Medicine and Department of Bioengineering, University of California, San Diego, La Jolla, CA, United States
| | - Arthur Forer
- Department of Biology, York University, Toronto, ON, Canada
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Blázquez-Castro A, Fernández-Piqueras J, Santos J. Genetic Material Manipulation and Modification by Optical Trapping and Nanosurgery-A Perspective. Front Bioeng Biotechnol 2020; 8:580937. [PMID: 33072730 PMCID: PMC7530750 DOI: 10.3389/fbioe.2020.580937] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/01/2020] [Indexed: 11/13/2022] Open
Abstract
Light can be employed as a tool to alter and manipulate matter in many ways. An example has been the implementation of optical trapping, the so called optical tweezers, in which light can hold and move small objects with 3D control. Of interest for the Life Sciences and Biotechnology is the fact that biological objects in the size range from tens of nanometers to hundreds of microns can be precisely manipulated through this technology. In particular, it has been shown possible to optically trap and move genetic material (DNA and chromatin) using optical tweezers. Also, these biological entities can be severed, rearranged and reconstructed by the combined use of laser scissors and optical tweezers. In this review, the background, current state and future possibilities of optical tweezers and laser scissors to manipulate, rearrange and alter genetic material (DNA, chromatin and chromosomes) will be presented. Sources of undesirable effects by the optical procedure and measures to avoid them will be discussed. In addition, first tentative approaches at cellular-level genetic and organelle surgery, in which genetic material or DNA-carrying organelles are extracted out or introduced into cells, will be presented.
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Affiliation(s)
- Alfonso Blázquez-Castro
- Department of Biology, Faculty of Sciences, Autonomous University of Madrid, Madrid, Spain.,Genome Dynamics and Function Program, Genome Decoding Unit, Severo Ochoa Molecular Biology Center (CBMSO), CSIC-Autonomous University of Madrid, Madrid, Spain
| | - José Fernández-Piqueras
- Department of Biology, Faculty of Sciences, Autonomous University of Madrid, Madrid, Spain.,Genome Dynamics and Function Program, Genome Decoding Unit, Severo Ochoa Molecular Biology Center (CBMSO), CSIC-Autonomous University of Madrid, Madrid, Spain.,Institute of Health Research Jiménez Diaz Foundation, Madrid, Spain.,Consortium for Biomedical Research in Rare Diseases (CIBERER), Carlos III Institute of Health, Madrid, Spain
| | - Javier Santos
- Department of Biology, Faculty of Sciences, Autonomous University of Madrid, Madrid, Spain.,Genome Dynamics and Function Program, Genome Decoding Unit, Severo Ochoa Molecular Biology Center (CBMSO), CSIC-Autonomous University of Madrid, Madrid, Spain.,Institute of Health Research Jiménez Diaz Foundation, Madrid, Spain.,Consortium for Biomedical Research in Rare Diseases (CIBERER), Carlos III Institute of Health, Madrid, Spain
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Forer A, Berns MW. Elastic Tethers Between Separating Anaphase Chromosomes Regulate the Poleward Speeds of the Attached Chromosomes in Crane-Fly Spermatocytes. Front Mol Biosci 2020; 7:161. [PMID: 32850955 PMCID: PMC7405647 DOI: 10.3389/fmolb.2020.00161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 06/24/2020] [Indexed: 01/09/2023] Open
Abstract
Elastic "tethers" connect separating anaphase chromosomes in most (or all) animal cells. We tested whether tethers are involved in coordinating movements of separating anaphase chromosomes in crane-fly spermatocytes. In these cells the coupled movements of separating chromosomes become uncoupled after the tethers are severed by laser microbeam irradiation of the interzone region between the chromosomes (Sheykhani et al., 2017). While this strongly suggests that tethers are involved with coordinating the poleward chromosome movements, the experiments are open to another interpretation: laser irradiations that cut the tethers also might damage something else in the interzone, and those non-tether components might regulate chromosome movements. In the experiments reported herein we distinguish between those two possibilities by disabling the tethers without cutting the interzone. We cut the arms from individual chromosomes, thereby severing the mechanical connection between separating chromosomes, disconnecting them, without damaging components in the interzone. Disabling tethers in this way uncoupled the movements of the separating chromosomes. We thus conclude that tethers are involved in regulating the speeds of separating anaphase chromosomes in crane-fly spermatocytes.
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Affiliation(s)
- Arthur Forer
- Biology Department, York University, North York, ON, Canada
| | - Michael W. Berns
- Department of Surgery, Biomedical Engineering and Developmental and Cell Biology, Beckman Laser Institute, University of California, Irvine, Irvine, CA, United States
- Department of Bioengineering, Institute for Engineering in Medicine, University of California, San Diego, San Diego, CA, United States
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Qu P, Wang Y, Zhang C, Liu E. Insights into the roles of sperm in animal cloning. Stem Cell Res Ther 2020; 11:65. [PMID: 32070430 PMCID: PMC7027237 DOI: 10.1186/s13287-020-01599-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 02/05/2020] [Accepted: 02/11/2020] [Indexed: 12/24/2022] Open
Abstract
Somatic cell nuclear transfer (SCNT) has shown a wide application in the generation of transgenic animals, protection of endangered animals, and therapeutic cloning. However, the efficiency of SCNT remains very low due to some poorly characterized key factors. Compared with fertilized embryos, somatic donor cells lack some important components of sperm, such as sperm small noncoding RNA (sncRNA) and proteins. Loss of these factors is considered an important reason for the abnormal development of SCNT embryo. This study focused on recent advances of SCNT and the roles of sperm in development. Sperm-derived factors play an important role in nucleus reprogramming and cytoskeleton remodeling during SCNT embryo development. Hence, considering the role of sperm may provide a new strategy for improving cloning efficiency.
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Affiliation(s)
- Pengxiang Qu
- Laboratory Animal Center, Xi'an Jiaotong University Health Science Center, No.76, Yanta West Road, Xi'an, 710061, Shaanxi, China
| | - Yongsheng Wang
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Chengsheng Zhang
- Precision Medicine Center, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, China.,The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA
| | - Enqi Liu
- Laboratory Animal Center, Xi'an Jiaotong University Health Science Center, No.76, Yanta West Road, Xi'an, 710061, Shaanxi, China.
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Forer A, Sheykhani R, Berns MW. Anaphase Chromosomes in Crane-Fly Spermatocytes Treated With Taxol (Paclitaxel) Accelerate When Their Kinetochore Microtubules Are Cut: Evidence for Spindle Matrix Involvement With Spindle Forces. Front Cell Dev Biol 2018; 6:77. [PMID: 30087895 PMCID: PMC6066604 DOI: 10.3389/fcell.2018.00077] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 06/29/2018] [Indexed: 01/01/2023] Open
Abstract
Various experiments have indicated that anaphase chromosomes continue to move after their kinetochore microtubules are severed. The chromosomes move poleward at an accelerated rate after the microtubules are cut but they slow down 1-3 min later and move poleward at near the original speed. There are two published interpretations of chromosome movements with severed kinetochore microtubules. One interpretation is that dynein relocates to the severed microtubule ends and propels them poleward by pushing against non-kinetochore microtubules. The other interpretation is that components of a putative "spindle matrix" normally push kinetochore microtubules poleward and continue to do so after the microtubules are severed from the pole. In this study we distinguish between these interpretations by treating cells with taxol. Taxol eliminates microtubule dynamics, alters spindle microtubule arrangements, and inhibits dynein motor activity in vivo. If the dynein interpretation is correct, taxol should interfere with chromosome movements after kinetochore microtubules are severed because it alters the arrangements of spindle microtubules and because it blocks dynein activity. If the "spindle matrix" interpretation is correct, on the other hand, taxol should not interfere with the accelerated movements. Our results support the spindle matrix interpretation: anaphase chromosomes in taxol-treated crane-fly spermatocytes accelerated after their kinetochore microtubules were severed.
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Affiliation(s)
- Arthur Forer
- Biology Department, York University, North York, ON, Canada
| | | | - Michael W Berns
- Beckman Laser Institute and Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, United States.,Department of Bioengineering and Institute for Engineering in Medicine, University of California, San Diego, San Diego, CA, United States
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Fegaras E, Forer A. Chromosomes selectively detach at one pole and quickly move towards the opposite pole when kinetochore microtubules are depolymerized in Mesostoma ehrenbergii spermatocytes. PROTOPLASMA 2018; 255:1205-1224. [PMID: 29468300 DOI: 10.1007/s00709-018-1214-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 01/18/2018] [Indexed: 06/08/2023]
Abstract
In a typical cell division, chromosomes align at the metaphase plate before anaphase commences. This is not the case in Mesostoma spermatocytes. Throughout prometaphase, the three bivalents persistently oscillate towards and away from either pole, at average speeds of 5-6 μm/min, without ever aligning at a metaphase plate. In our experiments, nocodazole (NOC) was added to prometaphase spermatocytes to depolymerize the microtubules. Traditional theories state that microtubules are the producers of force in the spindle, either by tubulin depolymerizing at the kinetochore (PacMan) or at the pole (Flux). Accordingly, if microtubules are quickly depolymerized, the chromosomes should arrest at the metaphase plate and not move. However, in 57/59 cells, at least one chromosome moved to a pole after NOC treatment, and in 52 of these cells, all three bivalents moved to the same pole. Thus, the movements are not random to one pole or other. After treatment with NOC, chromosome movement followed a consistent pattern. Bivalents stretched out towards both poles, paused, detached at one pole, and then the detached kinetochores quickly moved towards the other pole, reaching initial speeds up to more than 200 μm/min, much greater than anything previously recorded in this cell. As the NOC concentration increased, the average speeds increased and the microtubules disappeared faster. As the kinetochores approached the pole, they slowed down and eventually stopped. Similar results were obtained with colcemid treatment. Confocal immunofluorescence microscopy confirms that microtubules are not associated with moving chromosomes. Thus, these rapid chromosome movements may be due to non-microtubule spindle components such as actin-myosin or the spindle matrix.
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Affiliation(s)
- Eleni Fegaras
- Department of Biology, York University, 4700 Keele St, Toronto, ON, M3J 1P3, Canada
| | - Arthur Forer
- Department of Biology, York University, 4700 Keele St, Toronto, ON, M3J 1P3, Canada.
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Sheykhani R, Berns M, Forer A. Elastic tethers between separating anaphase chromosomes in crane-fly spermatocytes coordinate chromosome movements to the two poles. Cytoskeleton (Hoboken) 2017; 74:91-103. [PMID: 27935262 DOI: 10.1002/cm.21347] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 11/28/2016] [Accepted: 12/02/2016] [Indexed: 12/12/2022]
Abstract
Separating anaphase chromosomes in crane-fly spermatocytes are connected by elastic tethers, as originally described by LaFountain et al. (2002): telomere-containing arm fragments severed from the arms move backwards to the partner telomeres. We have tested whether the tethers coordinate the movements of separating partner chromosomes. In other cell types anaphase chromosomes move faster, temporarily, when their kinetochore microtubules are severed. However, in crane-fly spermatocytes the chromosomes move at their usual speed when their kinetochore microtubules are severed. To test whether the absence of increased velocity is because tethers link the separating chromosomes and coordinate their movements, we cut tethers with a laser microbeam and then cut the kinetochore microtubules. After this procedure, the associated chromosome sped up, as in other cells. These results indicate that the movements of partner anaphase chromosomes in crane-fly spermatocytes are coordinated by elastic tethers connecting the two chromosomes and confirm that chromosomes speed up in anaphase when their kinetochore microtubules are severed. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Rozhan Sheykhani
- Biology Department, York University, Toronto, Ontario, M3J 1P3, Canada
| | - Michael Berns
- Beckman Laser Institute and Department of Biomedical Engineering, University of California, Irvine, CA, 92617.,Department of Bioengineering and Institute for Engineering in Medicine, University of California, San Diego 92093
| | - Arthur Forer
- Biology Department, York University, Toronto, Ontario, M3J 1P3, Canada
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