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Janko K, Bartoš O, Kočí J, Roslein J, Drdová EJ, Kotusz J, Eisner J, Mokrejš M, Štefková-Kašparová E. Genome Fractionation and Loss of Heterozygosity in Hybrids and Polyploids: Mechanisms, Consequences for Selection, and Link to Gene Function. Mol Biol Evol 2021; 38:5255-5274. [PMID: 34410426 PMCID: PMC8662595 DOI: 10.1093/molbev/msab249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Hybridization and genome duplication have played crucial roles in the evolution of many animal and plant taxa. The subgenomes of parental species undergo considerable changes in hybrids and polyploids, which often selectively eliminate segments of one subgenome. However, the mechanisms underlying these changes are not well understood, particularly when the hybridization is linked with asexual reproduction that opens up unexpected evolutionary pathways. To elucidate this problem, we compared published cytogenetic and RNAseq data with exome sequences of asexual diploid and polyploid hybrids between three fish species; Cobitis elongatoides, C. taenia, and C. tanaitica. Clonal genomes remained generally static at chromosome-scale levels but their heterozygosity gradually deteriorated at the level of individual genes owing to allelic deletions and conversions. Interestingly, the impact of both processes varies among animals and genomic regions depending on ploidy level and the properties of affected genes. Namely, polyploids were more tolerant to deletions than diploid asexuals where conversions prevailed, and genomic restructuring events accumulated preferentially in genes characterized by high transcription levels and GC-content, strong purifying selection and specific functions like interacting with intracellular membranes. Although hybrids were phenotypically more similar to C. taenia, we found that they preferentially retained C. elongatoides alleles. This demonstrates that favored subgenome is not necessarily the transcriptionally dominant one. This study demonstrated that subgenomes in asexual hybrids and polyploids evolve under a complex interplay of selection and several molecular mechanisms whose efficiency depends on the organism's ploidy level, as well as functional properties and parental ancestry of the genomic region.
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Affiliation(s)
- Karel Janko
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Liběchov, Czech Republic
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Oldřich Bartoš
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Liběchov, Czech Republic
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jan Kočí
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Liběchov, Czech Republic
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Jan Roslein
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Liběchov, Czech Republic
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Edita Janková Drdová
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Jan Kotusz
- Museum of Natural History, University of Wroclaw, Wroclaw, Poland
| | - Jan Eisner
- Department of Mathematics, Faculty of Science, University of South Bohemia in České Budějovice, České Budějovice, Czech Republic
| | - Martin Mokrejš
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Liběchov, Czech Republic
- IT4Innovations, VŠB—Technical University of Ostrava, Ostrava-Poruba, Czech Republic
| | - Eva Štefková-Kašparová
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Liběchov, Czech Republic
- Department of Genetics and Breeding, FAFNR, Czech University of Life Sciences Prague, Czech Republic
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Brugler MR, Opresko DM, France SC. The evolutionary history of the order Antipatharia (Cnidaria: Anthozoa: Hexacorallia) as inferred from mitochondrial and nuclear DNA: implications for black coral taxonomy and systematics. Zool J Linn Soc 2013. [DOI: 10.1111/zoj.12060] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mercer R. Brugler
- Department of Biology; University of Louisiana at Lafayette; PO Box 42451 Lafayette LA USA
| | - Dennis M. Opresko
- Smithsonian Institution; National Museum of Natural History; Washington, DC USA
| | - Scott C. France
- Department of Biology; University of Louisiana at Lafayette; PO Box 42451 Lafayette LA USA
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Hu L, Huang X, Mao J, Wang C, Bao Z. Genomic characterization of interspecific hybrids between the scallops Argopecten purpuratus and A. irradians irradians. PLoS One 2013; 8:e62432. [PMID: 23620828 PMCID: PMC3631176 DOI: 10.1371/journal.pone.0062432] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 03/21/2013] [Indexed: 11/19/2022] Open
Abstract
The Peruvian scallop (Argopecten purpuratus) has been introduced to China and has successfully been hybridized with the bay scallop (A. irradians irradians). The F1 hybrids of these two scallops exhibited a large increase in production traits and some other interesting new characteristics. To understand the genetic basis of this heterosis, nuclear gene and partial mtDNA sequences, and genomic in situ hybridization (GISH) were employed to analyze the genomic organization of the hybrids. Amplification of the ribosomal DNA internal transcribed spacer (ITS) showed that the parental ITS sequences were present in all the hybrid individuals, illustrating that the hybrid offspring inherited nuclear DNA from both parents. Sequence analyses of the ITS region further confirmed that the hybrids harbored alleles from their parents; some recombinant variants were also detected, which revealed some alterations in the nuclear genetic material of the hybrids. The analysis of mitochondrial 16S rDNA showed that the hybrids possessed sequences that were identical to the 16S rDNA of the female parents, proving a matrilineal inheritance of mitochondrial genes in scallops. In addition, GISH clearly discriminated between the parental chromosomes and indicated a combination of haploid genomes of duplex parents in the hybrids. The genetic analyses in our study illustrated that the F1 hybrids inherited nuclear material from both parents and cytoplasmic genetic material maternally, and some variations occurred in the genome, which might contribute to a further understanding of crossbreeding and heterosis in scallop species.
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Affiliation(s)
- Liping Hu
- Key Laboratory of Marine Genetics and Breeding (MGB), Ministry of Education, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Xiaoting Huang
- Key Laboratory of Marine Genetics and Breeding (MGB), Ministry of Education, College of Marine Life Sciences, Ocean University of China, Qingdao, China
- * E-mail:
| | - Junxia Mao
- Key Laboratory of Marine Genetics and Breeding (MGB), Ministry of Education, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Chunde Wang
- College of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, China
| | - Zhenmin Bao
- Key Laboratory of Marine Genetics and Breeding (MGB), Ministry of Education, College of Marine Life Sciences, Ocean University of China, Qingdao, China
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Ling F, Mikawa T, Shibata T. Enlightenment of yeast mitochondrial homoplasmy: diversified roles of gene conversion. Genes (Basel) 2011; 2:169-90. [PMID: 24710143 PMCID: PMC3924846 DOI: 10.3390/genes2010169] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 01/18/2011] [Accepted: 01/25/2011] [Indexed: 11/29/2022] Open
Abstract
Mitochondria have their own genomic DNA. Unlike the nuclear genome, each cell contains hundreds to thousands of copies of mitochondrial DNA (mtDNA). The copies of mtDNA tend to have heterogeneous sequences, due to the high frequency of mutagenesis, but are quickly homogenized within a cell ("homoplasmy") during vegetative cell growth or through a few sexual generations. Heteroplasmy is strongly associated with mitochondrial diseases, diabetes and aging. Recent studies revealed that the yeast cell has the machinery to homogenize mtDNA, using a common DNA processing pathway with gene conversion; i.e., both genetic events are initiated by a double-stranded break, which is processed into 3' single-stranded tails. One of the tails is base-paired with the complementary sequence of the recipient double-stranded DNA to form a D-loop (homologous pairing), in which repair DNA synthesis is initiated to restore the sequence lost by the breakage. Gene conversion generates sequence diversity, depending on the divergence between the donor and recipient sequences, especially when it occurs among a number of copies of a DNA sequence family with some sequence variations, such as in immunoglobulin diversification in chicken. MtDNA can be regarded as a sequence family, in which the members tend to be diversified by a high frequency of spontaneous mutagenesis. Thus, it would be interesting to determine why and how double-stranded breakage and D-loop formation induce sequence homogenization in mitochondria and sequence diversification in nuclear DNA. We will review the mechanisms and roles of mtDNA homoplasmy, in contrast to nuclear gene conversion, which diversifies gene and genome sequences, to provide clues toward understanding how the common DNA processing pathway results in such divergent outcomes.
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Affiliation(s)
- Feng Ling
- Chemical Genetics Laboratory, RIKEN Advanced Science Institute/2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
| | - Tsutomu Mikawa
- Biometal Science Laboratory, RIKEN SPring-8 Center/Mikazuki cho, Hyogo 679-5148 Japan.
| | - Takehiko Shibata
- Division of Molecular and Cellular Physiology, Department of Supramolecular Biology, Graduate School of Nanobiosciences, Yokohama City University/1-7-29 Suehiro cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
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Alquezar DE, Hemmerter S, Cooper RD, Beebe NW. Incomplete concerted evolution and reproductive isolation at the rDNA locus uncovers nine cryptic species within Anopheles longirostris from Papua New Guinea. BMC Evol Biol 2010; 10:392. [PMID: 21184676 PMCID: PMC3022607 DOI: 10.1186/1471-2148-10-392] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2010] [Accepted: 12/24/2010] [Indexed: 11/20/2022] Open
Abstract
Background Nuclear ribosomal DNA (rDNA) genes and transcribed spacers are highly utilized as taxonomic markers in metazoans despite the lack of a cohesive understanding of their evolution. Here we follow the evolution of the rDNA second internal transcribed spacer (ITS2) and the mitochondrial DNA cytochrome oxidase I subunit in the malaria mosquito Anopheles longirostris from Papua New Guinea (PNG). This morphospecies inhabits a variety of ecological environments indicating that it may comprise a complex of morphologically indistinguishable species. Using collections from over 70 sites in PNG, the mtDNA was assessed via direct DNA sequencing while the ITS2 was assessed at three levels - crude sequence variation through restriction digest, intragenomic copy variant organisation (homogenisation) through heteroduplex analysis and DNA sequencing via cloning. Results Genetic evaluation of over 300 individuals revealed that A. longirostris comprises eight ITS2 PCR-RFLP genotypes and nine ITS2 heteroduplex genotypes showing distinct copy variant organization profiles after PCR amplification. Seven of these nine genotypes were found to be sympatric with other genotypes. Phylogenetic analysis of cloned ITS2 PCR products and mtDNA COI confirmed all nine clades with evidence of reproductive isolation at the rDNA locus. Compensatory base changes in the ITS2 secondary structure or in pseudoknots were absent when closely related species were assessed. Individuals from each ITS2 genotype showed the same copy variant heteroduplex profile suggesting that the rDNA array is fixed within each genotype. Conclusion The centromere-proximal position of the rDNA array in Anopheles mosquitoes has probably reduced interchromosomal recombination leaving intrachromosomal events responsible for the observed pattern of concerted evolution we see in these mosquitoes. The stability of these intragenomic ITS2 copy variants within individuals and interbreeding populations suggests that rDNA is moving as a single evolutionary unit through natural populations to fixation and has provided a complementary diagnostic tool to the restriction digest for studying genetic discontinuities and species boundaries. In this, the utility of the ITS2 as a universal taxonomic marker is probably contingent on several factors pertaining to spacer dimensions and the genomic location of the rDNA array with respect to recombination and proximity to regions potentially under selection.
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Affiliation(s)
- David E Alquezar
- Institute for the Biotechnology of Infectious Disease, University of Technology, Sydney. Australia
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