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Sacchi B, Humphries Z, Kružlicová J, Bodláková M, Pyne C, Choudhury BI, Gong Y, Bačovský V, Hobza R, Barrett SCH, Wright SI. Phased Assembly of Neo-Sex Chromosomes Reveals Extensive Y Degeneration and Rapid Genome Evolution in Rumex hastatulus. Mol Biol Evol 2024; 41:msae074. [PMID: 38606901 DOI: 10.1093/molbev/msae074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 01/31/2024] [Accepted: 04/05/2024] [Indexed: 04/13/2024] Open
Abstract
Y chromosomes are thought to undergo progressive degeneration due to stepwise loss of recombination and subsequent reduction in selection efficiency. However, the timescales and evolutionary forces driving degeneration remain unclear. To investigate the evolution of sex chromosomes on multiple timescales, we generated a high-quality phased genome assembly of the massive older (<10 MYA) and neo (<200,000 yr) sex chromosomes in the XYY cytotype of the dioecious plant Rumex hastatulus and a hermaphroditic outgroup Rumex salicifolius. Our assemblies, supported by fluorescence in situ hybridization, confirmed that the neo-sex chromosomes were formed by two key events: an X-autosome fusion and a reciprocal translocation between the homologous autosome and the Y chromosome. The enormous sex-linked regions of the X (296 Mb) and two Y chromosomes (503 Mb) both evolved from large repeat-rich genomic regions with low recombination; however, the complete loss of recombination on the Y still led to over 30% gene loss and major rearrangements. In the older sex-linked region, there has been a significant increase in transposable element abundance, even into and near genes. In the neo-sex-linked regions, we observed evidence of extensive rearrangements without gene degeneration and loss. Overall, we inferred significant degeneration during the first 10 million years of Y chromosome evolution but not on very short timescales. Our results indicate that even when sex chromosomes emerge from repetitive regions of already-low recombination, the complete loss of recombination on the Y chromosome still leads to a substantial increase in repetitive element content and gene degeneration.
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Affiliation(s)
- Bianca Sacchi
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
| | - Zoë Humphries
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
| | - Jana Kružlicová
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Markéta Bodláková
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | - Cassandre Pyne
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
| | - Baharul I Choudhury
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
- Department of Biology, Queen's University, Kingston, Canada
| | - Yunchen Gong
- Centre for Analysis of Genome Evolution and Function, University of Toronto, Toronto, Canada
| | - Václav Bačovský
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | - Roman Hobza
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
| | - Stephen I Wright
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
- Centre for Analysis of Genome Evolution and Function, University of Toronto, Toronto, Canada
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Guex LG, Sacchi B, Peuvot KF, Andersson RL, Pourrahimi AM, Ström V, Farris S, Olsson RT. Experimental review: chemical reduction of graphene oxide (GO) to reduced graphene oxide (rGO) by aqueous chemistry. Nanoscale 2017; 9:9562-9571. [PMID: 28664948 DOI: 10.1039/c7nr02943h] [Citation(s) in RCA: 174] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The electrical conductivity of reduced graphene oxide (rGO) obtained from graphene oxide (GO) using sodium borohydride (NaBH4) as a reducing agent has been investigated as a function of time (2 min to 24 h) and temperature (20 °C to 80 °C). Using a 300 mM aqueous NaBH4 solution at 80 °C, reduction of GO occurred to a large extent during the first 10 min, which yielded a conductivity increase of 5 orders of magnitude to 10 S m-1. During the residual 1400 min of reaction, the reduction rate decreased significantly, eventually resulting in a rGO conductivity of 1500 S m-1. High resolution XPS measurements showed that C/O increased from 2.2 for the GO to 6.9 for the rGO at the longest reaction times, due to the elimination of oxygen. The steep increase in conductivity recorded during the first 8-12 min of reaction was mainly due to the reduction of C-O (e.g., hydroxyl and epoxy) groups, suggesting the preferential attack of the reducing agent on C-O rather than C[double bond, length as m-dash]O groups. In addition, the specular variation of the percentage content of C-O bond functionalities with the sum of Csp2 and Csp3 indicated that the reduction of epoxy or hydroxyl groups had a greater impact on the restoration of the conductive nature of the graphite structure in rGO. These findings were reflected in the dramatic change in the structural stability of the rGO nanofoams produced by freeze-drying. The reduction protocol in this study allowed to achieve the highest conductivity values reported so far for the aqueous reduction of graphene oxide mediated by sodium borohydride. The 4-probe sheet resistivity approach used to measure the electrical conductivity is also, for the first time, presented in detail for filtrate sheet assemblies' of stacked GO/rGO sheets.
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Affiliation(s)
- L G Guex
- Department of Fibre and Polymer Technology, School of Chemical Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
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Cristini SI, Sacchi B, Guerrini E, Trasatti S, Trasatti SP. Detection of sigma phase in 22% Cr duplex stainless steel by electrochemical methods. RUSS J ELECTROCHEM+ 2010. [DOI: 10.1134/s1023193510100034] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Batani D, Morelli A, Tomasini M, Benuzzi-Mounaix A, Philippe F, Koenig M, Marchet B, Masclet I, Rabec M, Reverdin C, Cauble R, Celliers P, Collins G, Da Silva L, Hall T, Moret M, Sacchi B, Baclet P, Cathala B. Equation of state data for iron at pressures beyond 10 Mbar. Phys Rev Lett 2002; 88:235502. [PMID: 12059374 DOI: 10.1103/physrevlett.88.235502] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2001] [Indexed: 05/23/2023]
Abstract
We present equation of state points for iron, in the pressure range 10-45 Mbar, the first obtained with laser-driven shock waves. The experiment has been performed with the high energy laser Phebus, optically smoothed with Kinoform phase plates. Our results double the set of existing experimental data at very high pressures showing good agreement with the predictions of the quotidian equation of state model and with previous results.
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Affiliation(s)
- D Batani
- Dipartimento di Fisica "G. Occhialini," Università di Milano-Bicocca and INFM, Piazza della Scienza 3, 20126 Milano, Italy
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Ottaviani MF, Sacchi B, Turro NJ, Chen W, Jockusch S, Tomalia DA. An EPR Study of the Interactions between Starburst Dendrimers and Polynucleotides. Macromolecules 1999. [DOI: 10.1021/ma9815859] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
| | | | | | | | | | - D. A. Tomalia
- Michigan Molecular Institute, Midland, Michigan 48640
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