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Cheng CHC, Rivera-Colón AG, Minhas BF, Wilson L, Rayamajhi N, Vargas-Chacoff L, Catchen JM. Chromosome-Level Genome Assembly and Circadian Gene Repertoire of the Patagonia Blennie Eleginops maclovinus-The Closest Ancestral Proxy of Antarctic Cryonotothenioids. Genes (Basel) 2023; 14:1196. [PMID: 37372376 DOI: 10.3390/genes14061196] [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: 04/18/2023] [Revised: 05/26/2023] [Accepted: 05/26/2023] [Indexed: 06/29/2023] Open
Abstract
The basal South American notothenioid Eleginops maclovinus (Patagonia blennie or róbalo) occupies a uniquely important phylogenetic position in Notothenioidei as the singular closest sister species to the Antarctic cryonotothenioid fishes. Its genome and the traits encoded therein would be the nearest representatives of the temperate ancestor from which the Antarctic clade arose, providing an ancestral reference for deducing polar derived changes. In this study, we generated a gene- and chromosome-complete assembly of the E. maclovinus genome using long read sequencing and HiC scaffolding. We compared its genome architecture with the more basally divergent Cottoperca gobio and the derived genomes of nine cryonotothenioids representing all five Antarctic families. We also reconstructed a notothenioid phylogeny using 2918 proteins of single-copy orthologous genes from these genomes that reaffirmed E. maclovinus' phylogenetic position. We additionally curated E. maclovinus' repertoire of circadian rhythm genes, ascertained their functionality by transcriptome sequencing, and compared its pattern of gene retention with C. gobio and the derived cryonotothenioids. Through reconstructing circadian gene trees, we also assessed the potential role of the retained genes in cryonotothenioids by referencing to the functions of the human orthologs. Our results found E. maclovinus to share greater conservation with the Antarctic clade, solidifying its evolutionary status as the direct sister and best suited ancestral proxy of cryonotothenioids. The high-quality genome of E. maclovinus will facilitate inquiries into cold derived traits in temperate to polar evolution, and conversely on the paths of readaptation to non-freezing habitats in various secondarily temperate cryonotothenioids through comparative genomic analyses.
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Affiliation(s)
- Chi-Hing Christina Cheng
- Department of Evolution, Ecology and Behavior, University of Illinois, Urbana-Champaign, IL 61801, USA
| | - Angel G Rivera-Colón
- Department of Evolution, Ecology and Behavior, University of Illinois, Urbana-Champaign, IL 61801, USA
| | - Bushra Fazal Minhas
- Informatics Program, University of Illinois, Urbana-Champaign, IL 61801, USA
| | - Loralee Wilson
- Department of Evolution, Ecology and Behavior, University of Illinois, Urbana-Champaign, IL 61801, USA
| | - Niraj Rayamajhi
- Department of Evolution, Ecology and Behavior, University of Illinois, Urbana-Champaign, IL 61801, USA
| | - Luis Vargas-Chacoff
- Laboratorio de Fisiología de Peces, Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia 5090000, Chile
- Centro Fondap de Investigación de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia 5090000, Chile
- Millennium Institute Biodiversity of Antarctic and Subantarctic Ecosystems (BASE), Universidad Austral de Chile, Valdivia 5090000, Chile
| | - Julian M Catchen
- Department of Evolution, Ecology and Behavior, University of Illinois, Urbana-Champaign, IL 61801, USA
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Stanton D, Justin HS, Reitzel AM. Step in Time: Conservation of Circadian Clock Genes in Animal Evolution. Integr Comp Biol 2022; 62:1503-1518. [PMID: 36073444 DOI: 10.1093/icb/icac140] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 09/01/2022] [Accepted: 09/02/2022] [Indexed: 01/05/2023] Open
Abstract
Over the past few decades, the molecular mechanisms responsible for circadian phenotypes of animals have been studied in increasing detail in mammals, some insects, and other invertebrates. Particular circadian proteins and their interactions are shared across evolutionary distant animals, resulting in a hypothesis for the canonical circadian clock of animals. As the number of species for which the circadian clockwork has been described increases, the circadian clock in animals driving cyclical phenotypes becomes less similar. Our focus in this review is to develop and synthesize the current literature to better understand the antiquity and evolution of the animal circadian clockwork. Here, we provide an updated understanding of circadian clock evolution in animals, largely through the lens of conserved genes characterized in the circadian clock identified in bilaterian species. These comparisons reveal extensive variation within the likely composition of the core clock mechanism, including losses of many genes, and that the ancestral clock of animals does not equate to the bilaterian clock. Despite the loss of these core genes, these species retain circadian behaviors and physiology, suggesting novel clocks have evolved repeatedly. Additionally, we highlight highly conserved cellular processes (e.g., cell division, nutrition) that intersect with the circadian clock of some animals. The conservation of these processes throughout the animal tree remains essentially unknown, but understanding their role in the evolution and maintenance of the circadian clock will provide important areas for future study.
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Affiliation(s)
- Daniel Stanton
- Department of Animal Sciences, University of Florida, Gainesville, FL 32608, USA
| | - Hannah S Justin
- Department of Biological Sciences, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte NC 28223, USA
| | - Adam M Reitzel
- Department of Biological Sciences, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte NC 28223, USA
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3
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Bolton CM, Bekaert M, Eilertsen M, Helvik JV, Migaud H. Rhythmic Clock Gene Expression in Atlantic Salmon Parr Brain. Front Physiol 2021; 12:761109. [PMID: 34925060 PMCID: PMC8674837 DOI: 10.3389/fphys.2021.761109] [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: 08/19/2021] [Accepted: 11/09/2021] [Indexed: 12/28/2022] Open
Abstract
To better understand the complexity of clock genes in salmonids, a taxon with an additional whole genome duplication, an analysis was performed to identify and classify gene family members (clock, arntl, period, cryptochrome, nr1d, ror, and csnk1). The majority of clock genes, in zebrafish and Northern pike, appeared to be duplicated. In comparison to the 29 clock genes described in zebrafish, 48 clock genes were discovered in salmonid species. There was also evidence of species-specific reciprocal gene losses conserved to the Oncorhynchus sister clade. From the six period genes identified three were highly significantly rhythmic, and circadian in their expression patterns (per1a.1, per1a.2, per1b) and two was significantly rhythmically expressed (per2a, per2b). The transcriptomic study of juvenile Atlantic salmon (parr) brain tissues confirmed gene identification and revealed that there were 2,864 rhythmically expressed genes (p < 0.001), including 1,215 genes with a circadian expression pattern, of which 11 were clock genes. The majority of circadian expressed genes peaked 2 h before and after daylight. These findings provide a foundation for further research into the function of clock genes circadian rhythmicity and the role of an enriched number of clock genes relating to seasonal driven life history in salmonids.
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Affiliation(s)
- Charlotte M Bolton
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | - Michaël Bekaert
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | - Mariann Eilertsen
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Jon Vidar Helvik
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Herve Migaud
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
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Garcia-Concejo A, Larhammar D. Protein kinase C family evolution in jawed vertebrates. Dev Biol 2021; 479:77-90. [PMID: 34329618 DOI: 10.1016/j.ydbio.2021.07.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 07/02/2021] [Accepted: 07/22/2021] [Indexed: 11/18/2022]
Abstract
Protein kinase C (PKC) was one of the first kinases identified in human cells. It is now known to constitute a family of kinases that respond to diacylglycerol, phosphatidylserine and for some family members, Ca2+. They have a plethora of different functions, such as cell cycle regulation, immune response and memory formation. In mammals, 12 PKC family members have been described, usually divided into 4 different subfamilies. We present here a comprehensive evolutionary analysis of the PKC genes in jawed vertebrates with special focus on the impact of the two tetraploidizations (1R and 2R) before the radiation of jawed vertebrates and the teleost tetraploidization (3R), as illuminated by synteny and paralogon analysis including many neighboring gene families. We conclude that the vertebrate predecessor had five PKC genes, as tunicates and lancelets still do, and that the PKC family should therefore ideally be organized into five subfamilies. The 1R and 2R events led to a total of 12 genes distributed among these five subfamilies. All 12 genes are still present in some of the major lineages of jawed vertebrates, including mammals, whereas birds and cartilaginous fishes have lost one member. The 3R event added another nine genes in teleosts, bringing the total to 21 genes. The zebrafish, a common experimental model animal, has retained 19. We have found no independent gene duplications. Thus, the genome doublings completely account for the complexity of this gene family in jawed vertebrates and have thereby had a huge impact on their evolution.
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Affiliation(s)
- Adrian Garcia-Concejo
- Department of Neuroscience, Unit of Pharmacology, Science for Life Laboratory, Uppsala University, Box 593, SE-751 24, Uppsala, Sweden.
| | - Dan Larhammar
- Department of Neuroscience, Unit of Pharmacology, Science for Life Laboratory, Uppsala University, Box 593, SE-751 24, Uppsala, Sweden
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Mao Y, Shao F, Zhao Q, Peng Z. Molecular Evolution of clock Genes in Vertebrates. J Mol Evol 2021; 89:494-512. [PMID: 34297154 DOI: 10.1007/s00239-021-10020-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 06/27/2021] [Indexed: 11/24/2022]
Abstract
Circadian rhythms not only influence the overall daily routine of organisms but also directly affect life activities to varying degrees. Circadian locomotor output cycle kaput (Clock), the most critical gene in the circadian rhythm feedback system, plays an important role in the regulation of biological rhythms. Here, we aimed to elucidate the evolutionary history of the clock gene family in a taxonomically diverse set of vertebrates, providing novel insights into the evolution of the clock gene family based on 102 vertebrate genomes. Using genome-wide analysis, we extracted 264 clock sequences. In lobe-finned fishes and some basal non-teleost ray-finned fishes, only two clock isotypes were found (clock1 and clock2). However, the majority of teleosts possess three clock genes (two clock1 genes and one clock2 gene) owing to extra whole-genome duplication. The following syntenic analysis confirmed that clock1a, clock1b, and clock2 are conserved in teleost species. Interestingly, we discovered that osteoglossomorph fishes possess two clock2 genes. Moreover, protein sequence comparisons indicate that CLOCK protein changes among vertebrates were concentrated at the N-terminal and poly Q regions. We also performed a dN/dS analysis, and the results suggest that clock1 and clock2 may show distinct fates for duplicated genes between the lobe-finned and ray-finned fish clades. Collectively, these results provide a genome-wide insight into clock gene evolution in vertebrates.
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Affiliation(s)
- Yang Mao
- Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Southwest University School of Life Sciences, Chongqing, 400715, China
| | - Feng Shao
- Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Southwest University School of Life Sciences, Chongqing, 400715, China
| | - Qingyuan Zhao
- Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Southwest University School of Life Sciences, Chongqing, 400715, China
| | - Zuogang Peng
- Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Southwest University School of Life Sciences, Chongqing, 400715, China.
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6
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Zheng X, Zhang K, Zhao Y, Fent K. Environmental chemicals affect circadian rhythms: An underexplored effect influencing health and fitness in animals and humans. ENVIRONMENT INTERNATIONAL 2021; 149:106159. [PMID: 33508534 DOI: 10.1016/j.envint.2020.106159] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 09/21/2020] [Accepted: 09/21/2020] [Indexed: 06/12/2023]
Abstract
Circadian rhythms control the life of virtually all organisms. They regulate numerous aspects ranging from cellular processes to reproduction and behavior. Besides the light-dark cycle, there are additional environmental factors that regulate the circadian rhythms in animals as well as humans. Here, we outline the circadian rhythm system and considers zebrafish (Danio rerio) as a representative vertebrate organism. We characterize multiple physiological processes, which are affected by circadian rhythm disrupting compounds (circadian disrupters). We focus on and summarize 40 natural and anthropogenic environmental circadian disrupters in fish. They can be divided into six major categories: steroid hormones, metals, pesticides and biocides, polychlorinated biphenyls, neuroactive drugs and other compounds such as cyanobacterial toxins and bisphenol A. Steroid hormones as well as metals are most studied. Especially for progestins and glucocorticoids, circadian dysregulation was demonstrated in zebrafish on the molecular and physiological level, which comprise mainly behavioral alterations. Our review summarizes the current state of knowledge on circadian disrupters, highlights their risks to fish and identifies knowledge gaps in animals and humans. While most studies focus on transcriptional and behavioral alterations, additional effects and consequences are underexplored. Forthcoming studies should explore, which additional environmental circadian disrupters exist. They should clarify the underlying molecular mechanisms and aim to better understand the consequences for physiological processes.
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Affiliation(s)
- Xuehan Zheng
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Kun Zhang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Yanbin Zhao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
| | - Karl Fent
- University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Hofackerstrasse 30, CH-4132 Muttenz, Switzerland; ETH Zürich, Institute of Biogeochemistry and Pollution Dynamics, Department of Environmental Systems Science, CH-8092 Zürich, Switzerland.
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Moreno JM, Jesus TF, Coelho MM, Sousa VC. Adaptation and convergence in circadian-related genes in Iberian freshwater fish. BMC Ecol Evol 2021; 21:38. [PMID: 33685402 PMCID: PMC7941933 DOI: 10.1186/s12862-021-01767-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 02/16/2021] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND The circadian clock is a biological timing system that improves the ability of organisms to deal with environmental fluctuations. At the molecular level it consists of a network of transcription-translation feedback loops, involving genes that activate (bmal and clock - positive loop) and repress expression (cryptochrome (cry) and period (per) - negative loop). This is regulated by daily alternations of light but can also be affected by temperature. Fish, as ectothermic, depend on the environmental temperature and thus are good models to study its integration within the circadian system. Here, we studied the molecular evolution of circadian genes in four Squalius freshwater fish species, distributed across Western Iberian rivers affected by two climatic types with different environmental conditions (e.g., light and temperature). S. carolitertii and S. pyrenaicus inhabit the colder northern region under Atlantic climate type, while S. torgalensis, S. aradensis and some populations of S. pyrenaicus inhabit the warmer southern region affected by summer droughts, under Mediterranean climate type. RESULTS We identified 16 circadian-core genes in the Squalius species using a comparative transcriptomics approach. We detected evidence of positive selection in 12 of these genes using methods based on dN/dS. Positive selection was mainly found in cry and per genes of the negative loop, with 55 putatively adaptive substitutions, 16 located on protein domains. Evidence for positive selection is predominant in southern populations affected by the Mediterranean climate type. By predicting protein features we found that changes at sites under positive selection can impact protein thermostability by changing their aliphatic index and isoelectric point. Additionally, in nine genes, the phylogenetic clustering of species that belong to different clades but inhabit southern basins with similar environmental conditions indicated evolutionary convergence. We found evidence for increased nonsynonymous substitution rate in convergent lineages, likely due to positive selection at 27 sites, mostly in cry genes. CONCLUSIONS Our results support that temperature may be a selective pressure driving the evolution of genes involved in the circadian system. By integrating sequence-based functional protein prediction with dN/dS-based methods to detect selection we uncovered adaptive convergence in the southern populations, probably related to their similar thermal conditions.
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Affiliation(s)
- João M Moreno
- cE3c - Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016, Lisboa, Portugal
| | - Tiago F Jesus
- cE3c - Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016, Lisboa, Portugal
| | - Maria M Coelho
- cE3c - Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016, Lisboa, Portugal
| | - Vitor C Sousa
- cE3c - Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016, Lisboa, Portugal.
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8
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Bottalico LN, Weljie AM. Cross-species physiological interactions of endocrine disrupting chemicals with the circadian clock. Gen Comp Endocrinol 2021; 301:113650. [PMID: 33166531 PMCID: PMC7993548 DOI: 10.1016/j.ygcen.2020.113650] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 10/09/2020] [Accepted: 10/17/2020] [Indexed: 02/06/2023]
Abstract
Endocrine disrupting chemicals (EDCs) are endocrine-active chemical pollutants that disrupt reproductive, neuroendocrine, cardiovascular and metabolic health across species. The circadian clock is a transcriptional oscillator responsible for entraining 24-hour rhythms of physiology, behavior and metabolism. Extensive bidirectional cross talk exists between circadian and endocrine systems and circadian rhythmicity is present at all levels of endocrine control, from synthesis and release of hormones, to sensitivity of target tissues to hormone action. In mammals, a range of hormones directly alter clock gene expression and circadian physiology via nuclear receptor (NR) binding and subsequent genomic action, modulating physiological processes such as nutrient and energy metabolism, stress response, reproductive physiology and circadian behavioral rhythms. The potential for EDCs to perturb circadian clocks or circadian-driven physiology is not well characterized. For this reason, we explore evidence for parallel endocrine and circadian disruption following EDC exposure across species. In the reviewed studies, EDCs dysregulated core clock and circadian rhythm network gene expression in brain and peripheral organs, and altered circadian reproductive, behavioral and metabolic rhythms. Circadian impacts occurred in parallel to endocrine and metabolic alterations such as impaired fertility and dysregulated metabolic and energetic homeostasis. Further research is warranted to understand the nature of interaction between circadian and endocrine systems in mediating physiological effects of EDC exposure at environmental levels.
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Affiliation(s)
- Lisa N Bottalico
- Department of Systems Pharmacology and Translational Therapeutics, Institute for Translational Medicine and Therapeutics, Center of Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Aalim M Weljie
- Department of Systems Pharmacology and Translational Therapeutics, Institute for Translational Medicine and Therapeutics, Center of Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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Lu Y, Boswell M, Boswell W, Salinas RY, Savage M, Reyes J, Walter S, Marks R, Gonzalez T, Medrano G, Warren WC, Schartl M, Walter RB. Global assessment of organ specific basal gene expression over a diurnal cycle with analyses of gene copies exhibiting cyclic expression patterns. BMC Genomics 2020; 21:787. [PMID: 33176680 PMCID: PMC7659085 DOI: 10.1186/s12864-020-07202-9] [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: 01/27/2020] [Accepted: 10/28/2020] [Indexed: 11/25/2022] Open
Abstract
Background Studying functional divergences between paralogs that originated from genome duplication is a significant topic in investigating molecular evolution. Genes that exhibit basal level cyclic expression patterns including circadian and light responsive genes are important physiological regulators. Temporal shifts in basal gene expression patterns are important factors to be considered when studying genetic functions. However, adequate efforts have not been applied to studying basal gene expression variation on a global scale to establish transcriptional activity baselines for each organ. Furthermore, the investigation of cyclic expression pattern comparisons between genome duplication created paralogs, and potential functional divergence between them has been neglected. To address these questions, we utilized a teleost fish species, Xiphophorus maculatus, and profiled gene expression within 9 organs at 3-h intervals throughout a 24-h diurnal period. Results Our results showed 1.3–21.9% of genes in different organs exhibited cyclic expression patterns, with eye showing the highest fraction of cycling genes while gonads yielded the lowest. A majority of the duplicated gene pairs exhibited divergences in their basal level expression patterns wherein only one paralog exhibited an oscillating expression pattern, or both paralogs exhibit oscillating expression patterns, but each gene duplicate showed a different peak expression time, and/or in different organs. Conclusions These observations suggest cyclic genes experienced significant sub-, neo-, or non-functionalization following the teleost genome duplication event. In addition, we developed a customized, web-accessible, gene expression browser to facilitate data mining and data visualization for the scientific community.
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Affiliation(s)
- Yuan Lu
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA.
| | - Mikki Boswell
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA
| | - William Boswell
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA
| | - Raquel Ybanez Salinas
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA.,The University of Texas MD Anderson Cancer Center, Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Markita Savage
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA
| | - Jose Reyes
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA
| | - Sean Walter
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA
| | - Rebecca Marks
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA
| | - Trevor Gonzalez
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA
| | - Geraldo Medrano
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA
| | - Wesley C Warren
- Bond Life Sciences Center, University of Missouri, Columbia, MO, USA
| | - Manfred Schartl
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA.,Developmental Biochemistry, Theodor-Boveri-Institute, Biozentrum, University of Würzburg, Würzburg, Germany
| | - Ronald B Walter
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA
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Sun Y, Liu C, Huang M, Huang J, Liu C, Zhang J, Postlethwait JH, Wang H. The Molecular Evolution of Circadian Clock Genes in Spotted Gar ( Lepisosteus oculatus). Genes (Basel) 2019; 10:genes10080622. [PMID: 31426485 PMCID: PMC6723592 DOI: 10.3390/genes10080622] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/09/2019] [Accepted: 08/14/2019] [Indexed: 12/22/2022] Open
Abstract
Circadian rhythms are biological rhythms with a period of approximately 24 h. While canonical circadian clock genes and their regulatory mechanisms appear highly conserved, the evolution of clock gene families is still unclear due to several rounds of whole genome duplication in vertebrates. The spotted gar (Lepisosteus oculatus), as a non-teleost ray-finned fish, represents a fish lineage that diverged before the teleost genome duplication (TGD), providing an outgroup for exploring the evolutionary mechanisms of circadian clocks after whole-genome duplication. In this study, we interrogated the spotted gar draft genome sequences and found that spotted gar contains 26 circadian clock genes from 11 families. Phylogenetic analysis showed that 9 of these 11 spotted gar circadian clock gene families have the same number of genes as humans, while the members of the nfil3 and cry families are different between spotted gar and humans. Using phylogenetic and syntenic analyses, we found that nfil3-1 is conserved in vertebrates, while nfil3-2 and nfil3-3 are maintained in spotted gar, teleost fish, amphibians, and reptiles, but not in mammals. Following the two-round vertebrate genome duplication (VGD), spotted gar retained cry1a, cry1b, and cry2, and cry3 is retained in spotted gar, teleost fish, turtles, and birds, but not in mammals. We hypothesize that duplication of core clock genes, such as (nfil3 and cry), likely facilitated diversification of circadian regulatory mechanisms in teleost fish. We also found that the transcription factor binding element (Ahr::Arnt) is retained only in one of the per1 or per2 duplicated paralogs derived from the TGD in the teleost fish, implicating possible subfuctionalization cases. Together, these findings help decipher the repertoires of the spotted gar’s circadian system and shed light on how the vertebrate circadian clock systems have evolved.
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Affiliation(s)
- Yi Sun
- School of Biology & Basic Medical Sciences, Medical College of Soochow University, Suzhou 215123, China.
| | - Chao Liu
- School of Biology & Basic Medical Sciences, Medical College of Soochow University, Suzhou 215123, China
- Center for Circadian Clocks, Soochow University, Suzhou 215123, China
| | - Moli Huang
- School of Biology & Basic Medical Sciences, Medical College of Soochow University, Suzhou 215123, China
| | - Jian Huang
- School of Biology & Basic Medical Sciences, Medical College of Soochow University, Suzhou 215123, China
| | - Changhong Liu
- School of Biology & Basic Medical Sciences, Medical College of Soochow University, Suzhou 215123, China
| | - Jiguang Zhang
- School of Biology & Basic Medical Sciences, Medical College of Soochow University, Suzhou 215123, China
- Center for Circadian Clocks, Soochow University, Suzhou 215123, China
| | | | - Han Wang
- School of Biology & Basic Medical Sciences, Medical College of Soochow University, Suzhou 215123, China.
- Center for Circadian Clocks, Soochow University, Suzhou 215123, China.
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11
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Prokkola JM, Nikinmaa M. Circadian rhythms and environmental disturbances – underexplored interactions. J Exp Biol 2018; 221:221/16/jeb179267. [DOI: 10.1242/jeb.179267] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
ABSTRACT
Biological rhythms control the life of virtually all organisms, impacting numerous aspects ranging from subcellular processes to behaviour. Many studies have shown that changes in abiotic environmental conditions can disturb or entrain circadian (∼24 h) rhythms. These expected changes are so large that they could impose risks to the long-term viability of populations. Climate change is a major global stressor affecting the fitness of animals, partially because it challenges the adaptive associations between endogenous clocks and temperature – consequently, one can posit that a large-scale natural experiment on the plasticity of rhythm–temperature interactions is underway. Further risks are posed by chemical pollution and the depletion of oxygen levels in aquatic environments. Here, we focused our attention on fish, which are at heightened risk of being affected by human influence and are adapted to diverse environments showing predictable changes in light conditions, oxygen saturation and temperature. The examined literature to date suggests an abundance of mechanisms that can lead to interactions between responses to hypoxia, pollutants or pathogens and regulation of endogenous rhythms, but also reveals gaps in our understanding of the plasticity of endogenous rhythms in fish and in how these interactions may be disturbed by human influence and affect natural populations. Here, we summarize research on the molecular mechanisms behind environment–clock interactions as they relate to oxygen variability, temperature and responses to pollutants, and propose ways to address these interactions more conclusively in future studies.
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Affiliation(s)
- Jenni M. Prokkola
- Department of Biology, University of Turku, FI-20014 Turku, Finland
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Mikko Nikinmaa
- Department of Biology, University of Turku, FI-20014 Turku, Finland
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12
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Moonlight controls lunar-phase-dependency and regular oscillation of clock gene expressions in a lunar-synchronized spawner fish, Goldlined spinefoot. Sci Rep 2018; 8:6208. [PMID: 29670140 PMCID: PMC5906463 DOI: 10.1038/s41598-018-24538-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 04/06/2018] [Indexed: 12/25/2022] Open
Abstract
Goldlined spinefoot, Siganus guttatus, inhabits tropical and subtropical waters and synchronizes its spawning around the first quarter moon likely using an hourglass-like lunar timer. In previous studies, we have found that clock genes (Cryptochrome3 and Period1) could play the role of state variable in the diencephalon when determining the lunar phase for spawning. Here, we identified three Cry, two Per, two Clock, and two Bmal genes in S. guttatus and investigated their expression patterns in the diencephalon and pituitary gland. We further evaluated the effect on their expression patterns by daily interruptions of moonlight stimuli for 1 lunar cycle beginning at the new moon. It significantly modified the expression patterns in many of the examined clock(-related) genes including Cry3 in the diencephalon and/or pituitary gland. Acute interruptions of moonlight around the waxing gibbous moon upregulated nocturnal expressions of Cry1b and Cry2 in the diencephalon and pituitary gland, respectively, but did not affect expression levels of the other clock genes. These results highlighted the importance of repetitive moonlight illumination for stable or lunar-phase-specific daily expression of clock genes in the next lunar cycle that may be important for the lunar-phase-synchronized spawning on the next first quarter moon.
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13
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Light- and circadian-controlled genes respond to a broad light spectrum in Puffer Fish-derived Fugu eye cells. Sci Rep 2017; 7:46150. [PMID: 28418034 PMCID: PMC5394683 DOI: 10.1038/srep46150] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 03/10/2017] [Indexed: 11/08/2022] Open
Abstract
Some cell lines retain intrinsic phototransduction pathways to control the expression of light-regulated genes such as the circadian clock gene. Here we investigated the photosensitivity of a Fugu eye, a cell line established from the eye of Takifugu rubripes, to examine whether such a photosensitive nature is present. Microarray analysis identified 15 genes that showed blue light-dependent change at the transcript level. We investigated temporal profiles of the light-induced genes, as well as Cry and Per, under light-dark, constant light (LL), and constant dark (DD) conditions by quantitative RT-PCR. Transcript levels of Per1a and Per3 genes showed circadian rhythmic changes under both LL and DD conditions, while those of Cry genes were controlled by light. All genes examined, including DNA-damage response genes and photolyase genes, were upregulated not only by blue light but also green and red light, implying the contribution of multiple photopigments. The present study is the first to identify a photosensitive clock cell line originating from a marine fish. These findings may help to characterize the molecular mechanisms underlying photic synchronization of the physiological states of fishes to not only daily light-dark cycles but also to various marine environmental cycles such as the lunar or semi-lunar cycle.
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14
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Braasch I, Gehrke AR, Smith JJ, Kawasaki K, Manousaki T, Pasquier J, Amores A, Desvignes T, Batzel P, Catchen J, Berlin AM, Campbell MS, Barrell D, Martin KJ, Mulley JF, Ravi V, Lee AP, Nakamura T, Chalopin D, Fan S, Wcisel D, Cañestro C, Sydes J, Beaudry FEG, Sun Y, Hertel J, Beam MJ, Fasold M, Ishiyama M, Johnson J, Kehr S, Lara M, Letaw JH, Litman GW, Litman RT, Mikami M, Ota T, Saha NR, Williams L, Stadler PF, Wang H, Taylor JS, Fontenot Q, Ferrara A, Searle SMJ, Aken B, Yandell M, Schneider I, Yoder JA, Volff JN, Meyer A, Amemiya CT, Venkatesh B, Holland PWH, Guiguen Y, Bobe J, Shubin NH, Di Palma F, Alföldi J, Lindblad-Toh K, Postlethwait JH. The spotted gar genome illuminates vertebrate evolution and facilitates human-teleost comparisons. Nat Genet 2016; 48:427-37. [PMID: 26950095 PMCID: PMC4817229 DOI: 10.1038/ng.3526] [Citation(s) in RCA: 400] [Impact Index Per Article: 50.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Accepted: 02/12/2016] [Indexed: 12/16/2022]
Abstract
To connect human biology to fish biomedical models, we sequenced the genome of spotted gar (Lepisosteus oculatus), whose lineage diverged from teleosts before teleost genome duplication (TGD). The slowly evolving gar genome has conserved in content and size many entire chromosomes from bony vertebrate ancestors. Gar bridges teleosts to tetrapods by illuminating the evolution of immunity, mineralization and development (mediated, for example, by Hox, ParaHox and microRNA genes). Numerous conserved noncoding elements (CNEs; often cis regulatory) undetectable in direct human-teleost comparisons become apparent using gar: functional studies uncovered conserved roles for such cryptic CNEs, facilitating annotation of sequences identified in human genome-wide association studies. Transcriptomic analyses showed that the sums of expression domains and expression levels for duplicated teleost genes often approximate the patterns and levels of expression for gar genes, consistent with subfunctionalization. The gar genome provides a resource for understanding evolution after genome duplication, the origin of vertebrate genomes and the function of human regulatory sequences.
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Affiliation(s)
- Ingo Braasch
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, USA
| | - Andrew R Gehrke
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois, USA
| | - Jeramiah J Smith
- Department of Biology, University of Kentucky, Lexington, Kentucky, USA
| | - Kazuhiko Kawasaki
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Tereza Manousaki
- Institute of Marine Biology, Biotechnology and Aquaculture, Hellenic Centre for Marine Research, Heraklion, Greece
| | - Jeremy Pasquier
- Institut National de la Recherche Agronomique (INRA), UR1037 Laboratoire de Physiologie et Génomique des Poissons (LPGP), Campus de Beaulieu, Rennes, France
| | - Angel Amores
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, USA
| | - Thomas Desvignes
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, USA
| | - Peter Batzel
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, USA
| | - Julian Catchen
- Department of Animal Biology, University of Illinois, Urbana-Champaign, Illinois, USA
| | - Aaron M Berlin
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Michael S Campbell
- Eccles Institute of Human Genetics, University of Utah, Salt Lake City, Utah, USA
| | - Daniel Barrell
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, UK
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, UK
| | - Kyle J Martin
- Department of Zoology, University of Oxford, Oxford, UK
| | - John F Mulley
- School of Biological Sciences, Bangor University, Bangor, UK
| | - Vydianathan Ravi
- Comparative Genomics Laboratory, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Alison P Lee
- Comparative Genomics Laboratory, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Tetsuya Nakamura
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois, USA
| | - Domitille Chalopin
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Shaohua Fan
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Dustin Wcisel
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, North Carolina, USA
- Center for Comparative Medicine and Translational Research, North Carolina State University, Raleigh, North Carolina, USA
| | - Cristian Cañestro
- Departament de Genètica, Universitat de Barcelona, Barcelona, Spain
- Institut de Recerca de la Biodiversitat, Universitat de Barcelona, Barcelona, Spain
| | - Jason Sydes
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, USA
| | - Felix E G Beaudry
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
| | - Yi Sun
- Center for Circadian Clocks, Soochow University, Suzhou, China
- School of Biology and Basic Medical Sciences, Medical College, Soochow University, Suzhou, China
| | - Jana Hertel
- Bioinformatics Group, Department of Computer Science, Universität Leipzig, Leipzig, Germany
| | - Michael J Beam
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, USA
| | - Mario Fasold
- Bioinformatics Group, Department of Computer Science, Universität Leipzig, Leipzig, Germany
| | - Mikio Ishiyama
- Department of Dental Hygiene, Nippon Dental University College at Niigata, Niigata, Japan
| | - Jeremy Johnson
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Steffi Kehr
- Bioinformatics Group, Department of Computer Science, Universität Leipzig, Leipzig, Germany
| | - Marcia Lara
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - John H Letaw
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, USA
| | - Gary W Litman
- Department of Pediatrics, University of South Florida Morsani College of Medicine, St. Petersburg, Florida, USA
| | - Ronda T Litman
- Department of Pediatrics, University of South Florida Morsani College of Medicine, St. Petersburg, Florida, USA
| | - Masato Mikami
- Department of Microbiology, Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan
| | - Tatsuya Ota
- Department of Evolutionary Studies of Biosystems, SOKENDAI (Graduate University for Advanced Studies), Hayama, Japan
| | - Nil Ratan Saha
- Molecular Genetics Program, Benaroya Research Institute, Seattle, Washington, USA
| | - Louise Williams
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Peter F Stadler
- Bioinformatics Group, Department of Computer Science, Universität Leipzig, Leipzig, Germany
| | - Han Wang
- Center for Circadian Clocks, Soochow University, Suzhou, China
- School of Biology and Basic Medical Sciences, Medical College, Soochow University, Suzhou, China
| | - John S Taylor
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
| | - Quenton Fontenot
- Department of Biological Sciences, Nicholls State University, Thibodaux, Louisiana, USA
| | - Allyse Ferrara
- Department of Biological Sciences, Nicholls State University, Thibodaux, Louisiana, USA
| | - Stephen M J Searle
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, UK
| | - Bronwen Aken
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, UK
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, UK
| | - Mark Yandell
- Eccles Institute of Human Genetics, University of Utah, Salt Lake City, Utah, USA
| | - Igor Schneider
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Belem, Brazil
| | - Jeffrey A Yoder
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, North Carolina, USA
- Center for Comparative Medicine and Translational Research, North Carolina State University, Raleigh, North Carolina, USA
| | - Jean-Nicolas Volff
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Axel Meyer
- Department of Biology, University of Konstanz, Konstanz, Germany
- International Max Planck Research School for Organismal Biology, University of Konstanz, Konstanz, Germany
| | - Chris T Amemiya
- Molecular Genetics Program, Benaroya Research Institute, Seattle, Washington, USA
| | - Byrappa Venkatesh
- Comparative Genomics Laboratory, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore
| | | | - Yann Guiguen
- Institut National de la Recherche Agronomique (INRA), UR1037 Laboratoire de Physiologie et Génomique des Poissons (LPGP), Campus de Beaulieu, Rennes, France
| | - Julien Bobe
- Institut National de la Recherche Agronomique (INRA), UR1037 Laboratoire de Physiologie et Génomique des Poissons (LPGP), Campus de Beaulieu, Rennes, France
| | - Neil H Shubin
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois, USA
| | | | - Jessica Alföldi
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Kerstin Lindblad-Toh
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
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15
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Mei Q, Sadovy Y, Dvornyk V. Molecular evolution of cryptochromes in fishes. Gene 2015; 574:112-20. [PMID: 26238701 DOI: 10.1016/j.gene.2015.07.086] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 07/03/2015] [Accepted: 07/30/2015] [Indexed: 11/18/2022]
Abstract
Circadian rhythmicity is an endogenous biological cycle of about 24h, which exists in cyanobacteria and fungi, plants and animals. Circadian rhythms improve the adaptability of organisms in both constant and changing environments. The cryptochrome (CRY) is a key element of the circadian system in various animal groups including fishes. We studied evolution of cryptochromes in the phylogenetically and ecologically diverse fish taxa. The phylogenetic tree of fish Cry features two major clades: Cry1 and Cry2. Teleosts possess extra copies of Cry1 due to the genome duplication, which resulted in 3 main paralogous subfamilies (1A, 1B and 1C). Cry1 experienced further diversification through additional duplications in some taxa. 1A of Cry1 is more conserved than the other paralogs (dN=0.010 ± 0.003, π=0.119 ± 0.058). The analysis of selection indicated that, while the Cry homologs in fish evolved under the different levels of selection pressure, strong purifying selection (average ω=0.017) dominated in their evolution.
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Affiliation(s)
- Qiming Mei
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, People's Republic of China
| | - Yvonne Sadovy
- School of Biological Sciences, University of Hong Kong, Pokfulam Rd., Hong Kong, SAR, People's Republic of China
| | - Volodymyr Dvornyk
- School of Biological Sciences, University of Hong Kong, Pokfulam Rd., Hong Kong, SAR, People's Republic of China; Department of Life Sciences, College of Science and General Studies, Alfaisal University, Riyadh, Saudi Arabia.
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16
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Grone BP, Maruska KP. Divergent evolution of two corticotropin-releasing hormone (CRH) genes in teleost fishes. Front Neurosci 2015; 9:365. [PMID: 26528116 PMCID: PMC4602089 DOI: 10.3389/fnins.2015.00365] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 09/22/2015] [Indexed: 11/13/2022] Open
Abstract
Genome duplication, thought to have happened twice early in vertebrate evolution and a third time in teleost fishes, gives rise to gene paralogs that can evolve subfunctions or neofunctions via sequence and regulatory changes. To explore the evolution and functions of corticotropin-releasing hormone (CRH), we searched sequenced teleost genomes for CRH paralogs. Our phylogenetic and synteny analyses indicate that two CRH genes, crha and crhb, evolved via duplication of crh1 early in the teleost lineage. We examined the expression of crha and crhb in two teleost species from different orders: an African cichlid, Burton's mouthbrooder, (Astatotilapia burtoni; Order Perciformes) and zebrafish (Danio rerio; Order Cypriniformes). Furthermore, we compared expression of the teleost crha and crhb genes with the crh1 gene of an outgroup to the teleost clade: the spotted gar (Lepisosteus oculatus). In situ hybridization for crha and crhb mRNA in brains and eyes revealed distinct expression patterns for crha in different teleost species. In the cichlid, crha mRNA was found in the retina but not in the brain. In zebrafish, however, crha mRNA was not found in the retina, but was detected in the brain, restricted to the ventral hypothalamus. Spotted gar crh1 was found in the retina as well as the brain, suggesting that the ancestor of teleost fishes likely had a crh1 gene expressed in both retina and brain. Thus, genome duplication may have freed crha from constraints, allowing it to evolve distinct sequences, expression patterns, and likely unique functions in different lineages.
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Affiliation(s)
- Brian P Grone
- Department of Neurological Surgery, University of California, San Francisco San Francisco, CA, USA
| | - Karen P Maruska
- Department of Biological Sciences, Louisiana State University Baton Rouge, LA, USA
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