1
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Vigneau J, Martinho C, Godfroy O, Zheng M, Haas FB, Borg M, Coelho SM. Interactions between U and V sex chromosomes during the life cycle of Ectocarpus. Development 2024; 151:dev202677. [PMID: 38512707 PMCID: PMC11057875 DOI: 10.1242/dev.202677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 03/01/2024] [Indexed: 03/23/2024]
Abstract
In many animals and flowering plants, sex determination occurs in the diploid phase of the life cycle with XX/XY or ZW/ZZ sex chromosomes. However, in early diverging plants and most macroalgae, sex is determined by female (U) or male (V) sex chromosomes in a haploid phase called the gametophyte. Once the U and V chromosomes unite at fertilization to produce a diploid sporophyte, sex determination no longer occurs, raising key questions about the fate of the U and V sex chromosomes in the sporophyte phase. Here, we investigate genetic and molecular interactions of the UV sex chromosomes in both the haploid and diploid phases of the brown alga Ectocarpus. We reveal extensive developmental regulation of sex chromosome genes across its life cycle and implicate the TALE-HD transcription factor OUROBOROS in suppressing sex determination in the diploid phase. Small RNAs may also play a role in the repression of a female sex-linked gene, and transition to the diploid sporophyte coincides with major reconfiguration of histone H3K79me2, suggesting a more intricate role for this histone mark in Ectocarpus development than previously appreciated.
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Affiliation(s)
| | | | - Olivier Godfroy
- Roscoff Biological Station, CNRS-Sorbonne University, Place Georges Teissier, Roscoff 29680, France
| | - Min Zheng
- Max Planck Institute for Biology, 72076 Tübingen, Germany
| | - Fabian B. Haas
- Max Planck Institute for Biology, 72076 Tübingen, Germany
| | - Michael Borg
- Max Planck Institute for Biology, 72076 Tübingen, Germany
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2
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Jay P, Jeffries D, Hartmann FE, Véber A, Giraud T. Why do sex chromosomes progressively lose recombination? Trends Genet 2024; 40:564-579. [PMID: 38677904 DOI: 10.1016/j.tig.2024.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 03/18/2024] [Accepted: 03/19/2024] [Indexed: 04/29/2024]
Abstract
Progressive recombination loss is a common feature of sex chromosomes. Yet, the evolutionary drivers of this phenomenon remain a mystery. For decades, differences in trait optima between sexes (sexual antagonism) have been the favoured hypothesis, but convincing evidence is lacking. Recent years have seen a surge of alternative hypotheses to explain progressive extensions and maintenance of recombination suppression: neutral accumulation of sequence divergence, selection of nonrecombining fragments with fewer deleterious mutations than average, sheltering of recessive deleterious mutations by linkage to heterozygous alleles, early evolution of dosage compensation, and constraints on recombination restoration. Here, we explain these recent hypotheses and dissect their assumptions, mechanisms, and predictions. We also review empirical studies that have brought support to the various hypotheses.
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Affiliation(s)
- Paul Jay
- Center for GeoGenetics, University of Copenhagen, Copenhagen, Denmark; Université Paris-Saclay, CNRS, AgroParisTech, Laboratoire Ecologie Systématique et Evolution, UMR 8079, Bâtiment 680, 12 route RD128, 91190 Gif-sur-Yvette, France.
| | - Daniel Jeffries
- Division of Evolutionary Ecology, Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
| | - Fanny E Hartmann
- Université Paris-Saclay, CNRS, AgroParisTech, Laboratoire Ecologie Systématique et Evolution, UMR 8079, Bâtiment 680, 12 route RD128, 91190 Gif-sur-Yvette, France
| | - Amandine Véber
- Université Paris Cité, CNRS, MAP5, F-75006 Paris, France
| | - Tatiana Giraud
- Université Paris-Saclay, CNRS, AgroParisTech, Laboratoire Ecologie Systématique et Evolution, UMR 8079, Bâtiment 680, 12 route RD128, 91190 Gif-sur-Yvette, France
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3
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Luthringer R, Raphalen M, Guerra C, Colin S, Martinho C, Zheng M, Hoshino M, Badis Y, Lipinska AP, Haas FB, Barrera-Redondo J, Alva V, Coelho SM. Repeated co-option of HMG-box genes for sex determination in brown algae and animals. Science 2024; 383:eadk5466. [PMID: 38513029 DOI: 10.1126/science.adk5466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 01/31/2024] [Indexed: 03/23/2024]
Abstract
In many eukaryotes, genetic sex determination is not governed by XX/XY or ZW/ZZ systems but by a specialized region on the poorly studied U (female) or V (male) sex chromosomes. Previous studies have hinted at the existence of a dominant male-sex factor on the V chromosome in brown algae, a group of multicellular eukaryotes distantly related to animals and plants. The nature of this factor has remained elusive. Here, we demonstrate that an HMG-box gene acts as the male-determining factor in brown algae, mirroring the role HMG-box genes play in sex determination in animals. Over a billion-year evolutionary timeline, these lineages have independently co-opted the HMG box for male determination, representing a paradigm for evolution's ability to recurrently use the same genetic "toolkit" to accomplish similar tasks.
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Affiliation(s)
- Rémy Luthringer
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Morgane Raphalen
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Carla Guerra
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Sébastien Colin
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Claudia Martinho
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Min Zheng
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Masakazu Hoshino
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
- Research Center for Inland Seas, Kobe University, Kobe 658-0022, Japan
| | - Yacine Badis
- Roscoff Biological Station, CNRS-Sorbonne University, Place Georges Teissier, 29680 Roscoff, France
| | - Agnieszka P Lipinska
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Fabian B Haas
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Josué Barrera-Redondo
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Vikram Alva
- Department of Protein Evolution, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Susana M Coelho
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
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4
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Jia K, Duan J, Cheng G, Li H, Li S, Hu M. DNA Methylation is Involved in Sex Determination in Spinach. Biochem Genet 2023:10.1007/s10528-023-10524-4. [PMID: 37950843 DOI: 10.1007/s10528-023-10524-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Accepted: 09/07/2023] [Indexed: 11/13/2023]
Abstract
DNA methylation plays a critical role in the modulation of gene expression. The role of DNA methylation in sex determination was investigated in spinach. The differentiated cytosine CpG methylation profiles of CCGG motifs were assessed with methylation sensitivity amplification polymorphism (MSAP) in spinach. Among 442 DNA fragments from four plants, 134 methylated fragments were found. Relative proportions of methylation sites were 28.8% in male plants and 31.8% in female plants. At the same time, cytosine methylation levels were higher in females than in males in CCGG motifs of genomes in the spinach. These findings suggest that methylation of CG islands is involved in sex determination and differentiation in spinach.
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Affiliation(s)
- Keli Jia
- School of Medical Laboratory, Sanquan College of Xinxiang Medical University, Xinxiang, China
| | - Jiaming Duan
- School of Medical Laboratory, Sanquan College of Xinxiang Medical University, Xinxiang, China
| | | | - Heng Li
- School of Medical Laboratory, Sanquan College of Xinxiang Medical University, Xinxiang, China
| | - Shufen Li
- College of Life Sciences, Henan Normal University, Xinxiang, 453007, China.
| | - Miao Hu
- School of Medical Laboratory, Sanquan College of Xinxiang Medical University, Xinxiang, China.
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5
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Krasovec M, Hoshino M, Zheng M, Lipinska AP, Coelho SM. Low Spontaneous Mutation Rate in Complex Multicellular Eukaryotes with a Haploid-Diploid Life Cycle. Mol Biol Evol 2023; 40:msad105. [PMID: 37140022 PMCID: PMC10254074 DOI: 10.1093/molbev/msad105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/22/2023] [Accepted: 05/01/2023] [Indexed: 05/05/2023] Open
Abstract
The spontaneous mutation rate µ is a crucial parameter to understand evolution and biodiversity. Mutation rates are highly variable across species, suggesting that µ is susceptible to selection and drift and that species life cycle and life history may impact its evolution. In particular, asexual reproduction and haploid selection are expected to affect the mutation rate, but very little empirical data are available to test this expectation. Here, we sequence 30 genomes of a parent-offspring pedigree in the model brown alga Ectocarpus sp.7, and 137 genomes of an interspecific cross of the closely related brown alga Scytosiphon to have access to the spontaneous mutation rate of representative organisms of a complex multicellular eukaryotic lineage outside animals and plants, and to evaluate the potential impact of life cycle on the mutation rate. Brown algae alternate between a haploid and a diploid stage, both multicellular and free living, and utilize both sexual and asexual reproduction. They are, therefore, excellent models to empirically test expectations of the effect of asexual reproduction and haploid selection on mutation rate evolution. We estimate that Ectocarpus has a base substitution rate of µbs = 4.07 × 10-10 per site per generation, whereas the Scytosiphon interspecific cross had µbs = 1.22 × 10-9. Overall, our estimations suggest that these brown algae, despite being multicellular complex eukaryotes, have unusually low mutation rates. In Ectocarpus, effective population size (Ne) could not entirely explain the low µbs. We propose that the haploid-diploid life cycle, combined with extensive asexual reproduction, may be additional key drivers of the mutation rate in these organisms.
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Affiliation(s)
- Marc Krasovec
- Sorbonne Université, CNRS, UMR 7232 Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, Banyuls-sur-Mer, France
| | - Masakazu Hoshino
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Min Zheng
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Agnieszka P Lipinska
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Susana M Coelho
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
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6
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Geng X, Jia X, Liu L, Ma S, Liu H, Liu T. Gametophyte phase of commercial kelps, the potential food supplements for essential fatty acids and n-3 polyunsaturated fatty acids. J Food Sci 2023; 88:2411-2424. [PMID: 37167001 DOI: 10.1111/1750-3841.16596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 03/07/2023] [Accepted: 04/14/2023] [Indexed: 05/12/2023]
Abstract
For heteromorphic algae with alternating generations, the thallus and gametophyte phases are different morphologies in free-living life history. The thalli are popular used as traditional vegetables and herbal drugs, whereas the gametophyte phases are little involved. To better understand the functional lipids in the gametophyte phase of three commercial kelps, Saccharina japonica, Undaria pinnatifida, and Costaria costata, the contents of total lipids (TLs), fatty acid (FA) profiles, and transcriptomic analysis were performed. For the studied kelps, the TL contents in gametophyte phase were always almost twice more than those in the thallus, and the kelp species, their life stage, and the gender were critical factors affecting lipid accumulation. The gametophyte phases of U. pinnatifida and C. costata were rich in essential FA C18:2 n - 6 and C18:3 n - 3. The S. japonica gametophyte phase contained abundant C20:5 n - 3 and C18:4 n - 3, possessed an ideal ratio of n - 6/n - 3 polyunsaturated fatty acid below 1.0, and was supported by the transcriptome data which showed that the key sjD12/15 (n - 3) gene of gametophyte partially upregulated than sporophyte. The results suggested that S. japonica gametophyte phase was the worthiest of further development and utilization as a functional food. PRACTICAL APPLICATION: It is the first report on the fatty acid characteristics of three gametophyte phases of Saccharina japonica, Undaria pinnatifida, and Costaria costata and find that the S. japonica was worthy of further development and utilization as a functional food owing to its satisfactory fatty acid composition.
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Affiliation(s)
- Xicheng Geng
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, P. R. China
| | - Xuli Jia
- College of Marine Life Science, Ocean University of China, Qingdao, P. R. China
| | - Lanqing Liu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, P. R. China
| | - Shanpeng Ma
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, P. R. China
| | - Hongbing Liu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, P. R. China
- NMPA Key Laboratory for Quality Research and Evaluation of Marine Traditional Chinese Medicine, Qingdao, P. R. China
| | - Tao Liu
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, P.R. China
- Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, P.R. China
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7
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Hatchett WJ, Jueterbock AO, Kopp M, Coyer JA, Coelho SM, Hoarau G, Lipinska AP. Evolutionary dynamics of sex-biased gene expression in a young XY system: insights from the brown alga genus Fucus. THE NEW PHYTOLOGIST 2023; 238:422-437. [PMID: 36597732 DOI: 10.1111/nph.18710] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 12/16/2022] [Indexed: 06/17/2023]
Abstract
Sex-biased gene expression is considered to be an underlying cause of sexually dimorphic traits. Although the nature and degree of sex-biased expression have been well documented in several animal and plant systems, far less is known about the evolution of sex-biased genes in more distant eukaryotic groups. Here, we investigate sex-biased gene expression in two brown algal dioecious species, Fucus serratus and Fucus vesiculosus, where male heterogamety (XX/XY) has recently emerged. We find that in contrast to evolutionary distant plant and animal lineages, male-biased genes do not experience high turnover rates, but instead reveal remarkable conservation of bias and expression levels between the two species, suggesting their importance in sexual differentiation. Genes with consistent male bias were enriched in functions related to gamete production, along with sperm competition and include three flagellar proteins under positive selection. We present one of the first reports, outside of the animal kingdom, showing that male-biased genes display accelerated rates of coding sequence evolution compared with female-biased or unbiased genes. Our results imply that evolutionary forces affect male and female sex-biased genes differently on structural and regulatory levels, resulting in unique properties of differentially expressed transcripts during reproductive development in Fucus algae.
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Affiliation(s)
- William J Hatchett
- Faculty of Biosciences and Aquaculture, Nord University, 8026, Bodø, Norway
| | | | - Martina Kopp
- Faculty of Biosciences and Aquaculture, Nord University, 8026, Bodø, Norway
| | - James A Coyer
- Shoals Marine Laboratory, University of New Hampshire, Durham, NH, 03824, USA
| | - Susana M Coelho
- CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Sorbonne Université, Station Biologique de Roscoff, 29680, Roscoff, France
- Department of Algal Development and Evolution, Max Planck Institute for Biology, 72076, Tuebingen, Germany
| | - Galice Hoarau
- Faculty of Biosciences and Aquaculture, Nord University, 8026, Bodø, Norway
| | - Agnieszka P Lipinska
- CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Sorbonne Université, Station Biologique de Roscoff, 29680, Roscoff, France
- Department of Algal Development and Evolution, Max Planck Institute for Biology, 72076, Tuebingen, Germany
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8
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Cīrulis A, Hansson B, Abbott JK. Sex-limited chromosomes and non-reproductive traits. BMC Biol 2022; 20:156. [PMID: 35794589 PMCID: PMC9261002 DOI: 10.1186/s12915-022-01357-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 06/22/2022] [Indexed: 12/03/2022] Open
Abstract
Sex chromosomes are typically viewed as having originated from a pair of autosomes, and differentiated as the sex-limited chromosome (e.g. Y) has degenerated by losing most genes through cessation of recombination. While often thought that degenerated sex-limited chromosomes primarily affect traits involved in sex determination and sex cell production, accumulating evidence suggests they also influence traits not sex-limited or directly involved in reproduction. Here, we provide an overview of the effects of sex-limited chromosomes on non-reproductive traits in XY, ZW or UV sex determination systems, and discuss evolutionary processes maintaining variation at sex-limited chromosomes and molecular mechanisms affecting non-reproductive traits.
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Affiliation(s)
- Aivars Cīrulis
- Department of Biology, Lund University, 223 62, Lund, Sweden.
| | - Bengt Hansson
- Department of Biology, Lund University, 223 62, Lund, Sweden
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9
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Gueno J, Borg M, Bourdareau S, Cossard G, Godfroy O, Lipinska A, Tirichine L, Cock J, Coelho S. Chromatin landscape associated with sexual differentiation in a UV sex determination system. Nucleic Acids Res 2022; 50:3307-3322. [PMID: 35253891 PMCID: PMC8989524 DOI: 10.1093/nar/gkac145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 02/15/2022] [Accepted: 03/04/2022] [Indexed: 12/12/2022] Open
Abstract
In many eukaryotes, such as dioicous mosses and many algae, sex is determined by UV sex chromosomes and is expressed during the haploid phase of the life cycle. In these species, the male and female developmental programs are initiated by the presence of the U- or V-specific regions of the sex chromosomes but, as in XY and ZW systems, sexual differentiation is largely driven by autosomal sex-biased gene expression. The mechanisms underlying the regulation of sex-biased expression of genes during sexual differentiation remain elusive. Here, we investigated the extent and nature of epigenomic changes associated with UV sexual differentiation in the brown alga Ectocarpus, a model UV system. Six histone modifications were quantified in near-isogenic lines, leading to the identification of 16 chromatin signatures across the genome. Chromatin signatures correlated with levels of gene expression and histone PTMs changes in males versus females occurred preferentially at genes involved in sex-specific pathways. Despite the absence of chromosome scale dosage compensation and the fact that UV sex chromosomes recombine across most of their length, the chromatin landscape of these chromosomes was remarkably different to that of autosomes. Hotspots of evolutionary young genes in the pseudoautosomal regions appear to drive the exceptional chromatin features of UV sex chromosomes.
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Affiliation(s)
- Josselin Gueno
- Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff, France
| | - Michael Borg
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen72076, Tübingen, Germany
| | - Simon Bourdareau
- Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff, France
| | - Guillaume Cossard
- Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff, France
| | - Olivier Godfroy
- Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff, France
| | - Agnieszka Lipinska
- Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff, France
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen72076, Tübingen, Germany
| | - Leila Tirichine
- Nantes Universite, CNRS, US2B, UMR 6286, F-44000, Nantes, France
| | - J Mark Cock
- Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff, France
| | - Susana M Coelho
- Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff, France
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen72076, Tübingen, Germany
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10
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Foe VE. Does the Pachytene Checkpoint, a Feature of Meiosis, Filter Out Mistakes in Double-Strand DNA Break Repair and as a side-Effect Strongly Promote Adaptive Speciation? Integr Org Biol 2022; 4:obac008. [PMID: 36827645 PMCID: PMC8998493 DOI: 10.1093/iob/obac008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
This essay aims to explain two biological puzzles: why eukaryotic transcription units are composed of short segments of coding DNA interspersed with long stretches of non-coding (intron) DNA, and the near ubiquity of sexual reproduction. As is well known, alternative splicing of its coding sequences enables one transcription unit to produce multiple variants of each encoded protein. Additionally, padding transcription units with non-coding DNA (often many thousands of base pairs long) provides a readily evolvable way to set how soon in a cell cycle the various mRNAs will begin being expressed and the total amount of mRNA that each transcription unit can make during a cell cycle. This regulation complements control via the transcriptional promoter and facilitates the creation of complex eukaryotic cell types, tissues, and organisms. However, it also makes eukaryotes exceedingly vulnerable to double-strand DNA breaks, which end-joining break repair pathways can repair incorrectly. Transcription units cover such a large fraction of the genome that any mis-repair producing a reorganized chromosome has a high probability of destroying a gene. During meiosis, the synaptonemal complex aligns homologous chromosome pairs and the pachytene checkpoint detects, selectively arrests, and in many organisms actively destroys gamete-producing cells with chromosomes that cannot adequately synapse; this creates a filter favoring transmission to the next generation of chromosomes that retain the parental organization, while selectively culling those with interrupted transcription units. This same meiotic checkpoint, reacting to accidental chromosomal reorganizations inflicted by error-prone break repair, can, as a side effect, provide a mechanism for the formation of new species in sympatry. It has been a long-standing puzzle how something as seemingly maladaptive as hybrid sterility between such new species can arise. I suggest that this paradox is resolved by understanding the adaptive importance of the pachytene checkpoint, as outlined above.
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11
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Iwasaki M, Kajiwara T, Yasui Y, Yoshitake Y, Miyazaki M, Kawamura S, Suetsugu N, Nishihama R, Yamaoka S, Wanke D, Hashimoto K, Kuchitsu K, Montgomery SA, Singh S, Tanizawa Y, Yagura M, Mochizuki T, Sakamoto M, Nakamura Y, Liu C, Berger F, Yamato KT, Bowman JL, Kohchi T. Identification of the sex-determining factor in the liverwort Marchantia polymorpha reveals unique evolution of sex chromosomes in a haploid system. Curr Biol 2021; 31:5522-5532.e7. [PMID: 34735792 PMCID: PMC8699743 DOI: 10.1016/j.cub.2021.10.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 08/02/2021] [Accepted: 10/08/2021] [Indexed: 12/18/2022]
Abstract
Sex determination is a central process for sexual reproduction and is often regulated by a sex determinant encoded on a sex chromosome. Rules that govern the evolution of sex chromosomes via specialization and degeneration following the evolution of a sex determinant have been well studied in diploid organisms. However, distinct predictions apply to sex chromosomes in organisms where sex is determined in the haploid phase of the life cycle: both sex chromosomes, female U and male V, are expected to maintain their gene functions, even though both are non-recombining. This is in contrast to the X-Y (or Z-W) asymmetry and Y (W) chromosome degeneration in XY (ZW) systems of diploids. Here, we provide evidence that sex chromosomes diverged early during the evolution of haploid liverworts and identify the sex determinant on the Marchantia polymorpha U chromosome. This gene, Feminizer, encodes a member of the plant-specific BASIC PENTACYSTEINE transcription factor family. It triggers female differentiation via regulation of the autosomal sex-determining locus of FEMALE GAMETOPHYTE MYB and SUPPRESSOR OF FEMINIZATION. Phylogenetic analyses of Feminizer and other sex chromosome genes indicate dimorphic sex chromosomes had already been established 430 mya in the ancestral liverwort. Feminizer also plays a role in reproductive induction that is shared with its gametolog on the V chromosome, suggesting an ancestral function, distinct from sex determination, was retained by the gametologs. This implies ancestral functions can be preserved after the acquisition of a sex determination mechanism during the evolution of a dominant haploid sex chromosome system.
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Affiliation(s)
- Miyuki Iwasaki
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Tomoaki Kajiwara
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Yukiko Yasui
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | | | - Motoki Miyazaki
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Shogo Kawamura
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Noriyuki Suetsugu
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Ryuichi Nishihama
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan; Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan
| | - Shohei Yamaoka
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Dierk Wanke
- Department Biologie I, Ludwig-Maximilians-University (LMU), München 80638, Germany
| | - Kenji Hashimoto
- Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan
| | - Kazuyuki Kuchitsu
- Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan
| | - Sean A Montgomery
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Shilpi Singh
- School of Biological Sciences, Monash University, Melbourne, VIC 3800, Australia
| | - Yasuhiro Tanizawa
- National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka 411-8540, Japan
| | - Masaru Yagura
- National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka 411-8540, Japan
| | - Takako Mochizuki
- National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka 411-8540, Japan
| | - Mika Sakamoto
- National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka 411-8540, Japan
| | - Yasukazu Nakamura
- National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka 411-8540, Japan
| | - Chang Liu
- Institute of Biology, University of Hohenheim, Stuttgart 70599, Germany
| | - Frédéric Berger
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Katsuyuki T Yamato
- Faculty of Biology-Oriented Science and Technology (BOST), Kindai University, Kinokawa, Wakayama 649-6493, Japan
| | - John L Bowman
- School of Biological Sciences, Monash University, Melbourne, VIC 3800, Australia.
| | - Takayuki Kohchi
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
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12
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Constable GWA, Kokko H. Parthenogenesis and the Evolution of Anisogamy. Cells 2021; 10:2467. [PMID: 34572116 PMCID: PMC8467976 DOI: 10.3390/cells10092467] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 01/10/2023] Open
Abstract
Recently, it was pointed out that classic models for the evolution of anisogamy do not take into account the possibility of parthenogenetic reproduction, even though sex is facultative in many relevant taxa (e.g., algae) that harbour both anisogamous and isogamous species. Here, we complement this recent analysis with an approach where we assume that the relationship between progeny size and its survival may differ between parthenogenetically and sexually produced progeny, favouring either the former or the latter. We show that previous findings that parthenogenesis can stabilise isogamy relative to the obligate sex case, extend to our scenarios. We additionally investigate two different ways for one mating type to take over the entire population. First, parthenogenesis can lead to biased sex ratios that are sufficiently extreme that one type can displace the other, leading to de facto asexuality for the remaining type that now lacks partners to fuse with. This process involves positive feedback: microgametes, being numerous, lack opportunities for syngamy, and should they proliferate parthenogenetically, the next generation makes this asexual route even more prominent for microgametes. Second, we consider mutations to strict asexuality in producers of micro- or macrogametes, and show that the prospects of asexual invasion depend strongly on the mating type in which the mutation arises. Perhaps most interestingly, we also find scenarios in which parthenogens have an intrinsic survival advantage yet facultatively sexual isogamous populations are robust to the invasion of asexuals, despite us assuming no genetic benefits of recombination. Here, equal contribution from both mating types to zygotes that are sufficiently well provisioned can outweigh the additional costs associated with syngamy.
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Affiliation(s)
| | - Hanna Kokko
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, CH-8057 Zurich, Switzerland
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13
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Zhang J, Li Y, Luo S, Cao M, Zhang L, Li X. Differential gene expression patterns during gametophyte development provide insights into sex differentiation in the dioicous kelp Saccharina japonica. BMC PLANT BIOLOGY 2021; 21:335. [PMID: 34261451 PMCID: PMC8278619 DOI: 10.1186/s12870-021-03117-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 06/23/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND In brown algae, dioicy is the prevalent sexual system, and phenotypic differences between male and female gametophytes have been found in many dioicous species. Saccharina japonica show remarkable sexual dimorphism in gametophytes before gametogenesis. A higher level of phenotypic differentiation was also found in female and male gametes after gametogenesis. However, the patterns of differential gene expression throughout gametophyte development and how these changes might relate to sex-specific fitness at the gamete stage in S. japonica are not well known. RESULTS In this study, differences in gene expression between male and female gametophytes in different developmental stages were investigated using comparative transcriptome analysis. Among the 20,151 genes expressed in the haploid gametophyte generation, 37.53% were sex-biased. The abundance of sex-biased genes in mature gametophytes was much higher than that in immature gametophytes, and more male-biased than female-biased genes were observed in the mature stage. The predicted functions of most sex-biased genes were closely related to the sex-specific characteristics of gametes, including cell wall biosynthesis, sperm motility, and sperm and egg recognition. In addition, 51 genes were specifically expressed in males in both stages, showing great potential as candidate male sex-determining region (SDR) genes. CONCLUSIONS This study describes a thorough investigation into differential gene expression between male and female gametophytes in the dioicous kelp S. japonica. A large number of sex-biased genes in mature gametophytes may be associated with the divergence of phenotypic traits and physiological functions between female gametes (eggs) and male gametes (sperm) during sexual differentiation. These genes may mainly come from new sex-biased genes that have recently evolved in the S. japonica lineage. The duplication of sex-biased genes was detected, which may increase the number of sex-biased genes after gametogenesis in S. japonica to some extent. The excess of male-biased genes over female-biased genes in the mature stage may reflect the different levels of sexual selection across sexes. This study deepens our understanding of the regulation of sex development and differentiation in the dioicous kelp S. japonica.
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Affiliation(s)
- Jiaxun Zhang
- School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, 266109, China
| | - Yan Li
- National Engineering Science Research & Development Center of Algae and Sea Cucumbers of China, Provincial Key Laboratory of Genetic Improvement & Efficient Culture of Marine Algae of Shandong, Shandong Oriental Ocean Sci-Tech Co., Ltd., Yantai, 264003, China
| | - Shiju Luo
- National Engineering Science Research & Development Center of Algae and Sea Cucumbers of China, Provincial Key Laboratory of Genetic Improvement & Efficient Culture of Marine Algae of Shandong, Shandong Oriental Ocean Sci-Tech Co., Ltd., Yantai, 264003, China
| | - Min Cao
- School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, 266109, China
| | - Linan Zhang
- School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, 266109, China.
| | - Xiaojie Li
- National Engineering Science Research & Development Center of Algae and Sea Cucumbers of China, Provincial Key Laboratory of Genetic Improvement & Efficient Culture of Marine Algae of Shandong, Shandong Oriental Ocean Sci-Tech Co., Ltd., Yantai, 264003, China
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14
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Drakard VF, Brooks P, Crowe TP, Earp HS, Thompson B, Bourke N, George R, Piper C, Moore PJ. Fucus vesiculosus populations on artificial structures have potentially reduced fecundity and are dislodged at greater rates than on natural shores. MARINE ENVIRONMENTAL RESEARCH 2021; 168:105324. [PMID: 33845257 DOI: 10.1016/j.marenvres.2021.105324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 03/24/2021] [Accepted: 03/25/2021] [Indexed: 06/12/2023]
Abstract
Artificial structures are widespread features of coastal marine environments. These structures, however, are poor surrogates of natural rocky shores, meaning they generally support depauperate assemblages with reduced population sizes. Little is known about sub-lethal effects of such structures, for example, in terms of demographic properties and reproductive potential that may affect the dynamics and long-term viability of populations. Such understanding is particularly important for ecosystem engineer species, such as the intertidal seaweed Fucus vesiculosus. In this study, F. vesiculosus was sampled on eight artificial structures and eight natural shores along the east coast of Ireland and the west coast of Wales. Algal percentage cover, biomass, density of individuals, and growth rate did not differ between artificial and natural shores. Growth and reproductive cycles were consistent with previous studies for this species. While there was considerable variation from site to site, on average, populations on natural shores produced a higher number of mature receptacles during the peak reproductive period in April, and lower rates of dislodgement than on artificial structures. As F. vesiculosus reach peak reproductive output after 24 months, this suggests that individuals may be removed from populations on artificial structures before reaching their full reproductive potential. In this case, this did not influence density, percentage cover, or biomass, which suggests that F. vesiculosus populations on artificial structures may function similarly to those on natural shores if supported by suitable source populations, but potentially may not persist otherwise.
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Affiliation(s)
- Veronica Farrugia Drakard
- UCD Earth Institute and School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland.
| | - Paul Brooks
- UCD Earth Institute and School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - Tasman P Crowe
- UCD Earth Institute and School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - Hannah S Earp
- Institute of Biological, Environmental & Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, SY23 3DA, UK
| | - Bryan Thompson
- UCD Earth Institute and School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - Nathan Bourke
- UCD Earth Institute and School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - Ruby George
- Institute of Biological, Environmental & Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, SY23 3DA, UK
| | - Chloe Piper
- Institute of Biological, Environmental & Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, SY23 3DA, UK
| | - Pippa J Moore
- Institute of Biological, Environmental & Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, SY23 3DA, UK; School of Natural and Environmental Sciences, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK
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15
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Hartmann FE, Rodríguez de la Vega RC, Gladieux P, Ma WJ, Hood ME, Giraud T. Higher Gene Flow in Sex-Related Chromosomes than in Autosomes during Fungal Divergence. Mol Biol Evol 2020; 37:668-682. [PMID: 31651949 PMCID: PMC7038665 DOI: 10.1093/molbev/msz252] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Nonrecombining sex chromosomes are widely found to be more differentiated than autosomes among closely related species, due to smaller effective population size and/or to a disproportionally large-X effect in reproductive isolation. Although fungal mating-type chromosomes can also display large nonrecombining regions, their levels of differentiation compared with autosomes have been little studied. Anther-smut fungi from the Microbotryum genus are castrating pathogens of Caryophyllaceae plants with largely nonrecombining mating-type chromosomes. Using whole genome sequences of 40 fungal strains, we quantified genetic differentiation among strains isolated from the geographically overlapping North American species and subspecies of Silene virginica and S. caroliniana. We inferred that gene flow likely occurred at the early stages of divergence and then completely stopped. We identified large autosomal genomic regions with chromosomal inversions, with higher genetic divergence than the rest of the genomes and highly enriched in selective sweeps, supporting a role of rearrangements in preventing gene flow in genomic regions involved in ecological divergence. Unexpectedly, the nonrecombining mating-type chromosomes showed lower divergence than autosomes due to higher gene flow, which may be promoted by adaptive introgressions of less degenerated mating-type chromosomes. The fact that both mating-type chromosomes are always heterozygous and nonrecombining may explain such patterns that oppose to those found for XY or ZW sex chromosomes. The specific features of mating-type chromosomes may also apply to the UV sex chromosomes determining sexes at the haploid stage in algae and bryophytes and may help test general hypotheses on the evolutionary specificities of sex-related chromosomes.
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Affiliation(s)
- Fanny E Hartmann
- Ecologie Systematique Evolution, Batiment 360, Univ. Paris-Sud, AgroParisTech, CNRS, Université Paris-Saclay, Orsay, France
| | - Ricardo C Rodríguez de la Vega
- Ecologie Systematique Evolution, Batiment 360, Univ. Paris-Sud, AgroParisTech, CNRS, Université Paris-Saclay, Orsay, France
| | - Pierre Gladieux
- UMR BGPI, Univ Montpellier, INRA, CIRAD, Montpellier SupAgro, Montpellier, France
| | - Wen-Juan Ma
- Biology Department, Science Centre, Amherst College, Amherst, MA
| | - Michael E Hood
- Biology Department, Science Centre, Amherst College, Amherst, MA
| | - Tatiana Giraud
- Ecologie Systematique Evolution, Batiment 360, Univ. Paris-Sud, AgroParisTech, CNRS, Université Paris-Saclay, Orsay, France
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16
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Trenkel VM, Boudry P, Verrez-Bagnis V, Lorance P. Methods for identifying and interpreting sex-linked SNP markers and carrying out sex assignment: application to thornback ray (Raja clavata). Mol Ecol Resour 2020; 20:1610-1619. [PMID: 32657500 DOI: 10.1111/1755-0998.13225] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 06/18/2020] [Accepted: 07/08/2020] [Indexed: 11/28/2022]
Abstract
Sex-determining modes remain unknown in numerous species, notably in fishes, in which a variety of modalities have been reported. Additionally, noninvasive individual sexing is problematic for species without external sex attributes or for early life stages, requiring cytogenetic or molecular analyses when sex chromosomes or sex-linked markers have been characterized. Genomics now provide a means to achieve this. Here, we review common sex-determination systems and corresponding statistical methods for identifying sex-linked genetic markers and their use for sex assignment, focusing on single nucleotide polymorphism (SNP) markers derived from reduced representation sequencing methods. We demonstrate the dependence of expected sex assignment error on the number of sex-linked SNPs and minor allele frequency. The application of three methods was made here: (a) identification of heterozygote excess in one sex, (b) FST outlier analysis between the two sexes and (c) neuronal net modelling. These methods were applied to a large SNP data set (4604 SNPs) for 1680 thornback rays (Raja clavata). Using method (a), nineteen putative sex-linked SNPs were identified. Comparison with the reference genome of a related species (Amblyraja radiata) indicated that all 19 SNPs are probably located on the same chromosome. These results suggest that thornback ray has a XX/XY sex-determination system. Method (b) identified eight SNPs probably located on different chromosomes. Method (a) led to the lowest sex assignment error among the three methods (4.2% error for females and 3.7% for males).
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Affiliation(s)
| | - Pierre Boudry
- CNRS, IRD, LEMAR, Ifremer, Univ Brest, Plouzané, France
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17
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Pearson GA, Martins N, Madeira P, Serrão EA, Bartsch I. Sex-dependent and -independent transcriptional changes during haploid phase gametogenesis in the sugar kelp Saccharina latissima. PLoS One 2019; 14:e0219723. [PMID: 31513596 PMCID: PMC6742357 DOI: 10.1371/journal.pone.0219723] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 08/27/2019] [Indexed: 11/26/2022] Open
Abstract
In haplodiplontic lineages, sexual reproduction occurs in haploid parents without meiosis. Although widespread in multicellular lineages such as brown algae (Phaeophyceae), haplodiplontic gametogenesis has been little studied at the molecular level. We addressed this by generating an annotated reference transcriptome for the gametophytic phase of the sugar kelp, Saccharina latissima. Transcriptional profiles of microscopic male and female gametophytes were analysed at four time points during the transition from vegetative growth to gametogenesis. Gametogenic signals resulting from a switch in culture irradiance from red to white light activated a core set of genes in a sex-independent manner, involving rapid activation of ribosome biogenesis, transcription and translation related pathways, with several acting at the post-transcriptional or post-translational level. Additional genes regulating nutrient acquisition and key carbohydrate-energy pathways were also identified. Candidate sex-biased genes under gametogenic conditions had potentially key roles in controlling female- and male-specific gametogenesis. Among these were several sex-biased or -specific E3 ubiquitin-protein ligases that may have important regulatory roles. Females specifically expressed several genes that coordinate gene expression and/or protein degradation, and the synthesis of inositol-containing compounds. Other female-biased genes supported parallels with oogenesis in divergent multicellular lineages, in particular reactive oxygen signalling via an NADPH-oxidase. Males specifically expressed the hypothesised brown algal sex-determining factor. Male-biased expression mainly involved upregulation of genes that control mitotic cell proliferation and spermatogenesis in other systems, as well as multiple flagella-related genes. Our data and results enhance genome-level understanding of gametogenesis in this ecologically and economically important multicellular lineage.
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Affiliation(s)
- Gareth A. Pearson
- Centre for Marine Sciences (CCMAR)-CIMAR, University of Algarve, Portugal
| | - Neusa Martins
- Centre for Marine Sciences (CCMAR)-CIMAR, University of Algarve, Portugal
| | - Pedro Madeira
- Centre for Marine Sciences (CCMAR)-CIMAR, University of Algarve, Portugal
| | - Ester A. Serrão
- Centre for Marine Sciences (CCMAR)-CIMAR, University of Algarve, Portugal
| | - Inka Bartsch
- Alfred-Wegener-Institute, Helmholtz Center for Polar and Marine Research, Am Handelshafen, Germany
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18
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Abstract
Algae are photosynthetic eukaryotes whose taxonomic breadth covers a range of life histories, degrees of cellular and developmental complexity, and diverse patterns of sexual reproduction. These patterns include haploid- and diploid-phase sex determination, isogamous mating systems, and dimorphic sexes. Despite the ubiquity of sexual reproduction in algae, their mating-type-determination and sex-determination mechanisms have been investigated in only a limited number of representatives. These include volvocine green algae, where sexual cycles and sex-determining mechanisms have shed light on the transition from mating types to sexes, and brown algae, which are a model for UV sex chromosome evolution in the context of a complex haplodiplontic life cycle. Recent advances in genomics have aided progress in understanding sexual cycles in less-studied taxa including ulvophyte, charophyte, and prasinophyte green algae, as well as in diatoms.
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Affiliation(s)
- James Umen
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA;
| | - Susana Coelho
- Algal Genetics Group, Integrative Biology of Marine Models, Station Biologique de Roscoff, Sorbonne Université, UPMC Université Paris 06, CNRS, CS 90074, F-29688 Roscoff, France;
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