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Nagashima A, Torii K, Ota C, Kato A. slc26a12-A novel member of the slc26 family, is located in tandem with slc26a2 in coelacanths, amphibians, reptiles, and birds. Physiol Rep 2024; 12:e16089. [PMID: 38828713 PMCID: PMC11145369 DOI: 10.14814/phy2.16089] [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: 03/26/2024] [Revised: 05/16/2024] [Accepted: 05/16/2024] [Indexed: 06/05/2024] Open
Abstract
Solute carrier family 26 (Slc26) is a family of anion exchangers with 11 members in mammals (named Slc26a1-a11). Here, we identified a novel member of the slc26 family, slc26a12, located in tandem with slc26a2 in the genomes of several vertebrate lineages. BLAST and synteny analyses of various jawed vertebrate genome databases revealed that slc26a12 is present in coelacanths, amphibians, reptiles, and birds but not in cartilaginous fishes, lungfish, mammals, or ray-finned fishes. In some avian and reptilian lineages such as owls, penguins, egrets, and ducks, and most turtles examined, slc26a12 was lost or pseudogenized. Phylogenetic analysis showed that Slc26a12 formed an independent branch with the other Slc26 members and Slc26a12, Slc26a1 and Slc26a2 formed a single branch, suggesting that these three members formed a subfamily in Slc26. In jawless fish, hagfish have two genes homologous to slc26a2 and slc26a12, whereas lamprey has a single gene homologous to slc26a2. African clawed frogs express slc26a12 in larval gills, skin, and fins. These results show that slc26a12 was present at least before the separation of lobe-finned fish and tetrapods; the name slc26a12 is appropriate because the gene duplication occurred in the distant past.
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Affiliation(s)
- Ayumi Nagashima
- School of Life Science and TechnologyTokyo Institute of TechnologyYokohamaJapan
| | - Kota Torii
- School of Life Science and TechnologyTokyo Institute of TechnologyYokohamaJapan
| | - Chihiro Ota
- School of Life Science and TechnologyTokyo Institute of TechnologyYokohamaJapan
| | - Akira Kato
- School of Life Science and TechnologyTokyo Institute of TechnologyYokohamaJapan
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2
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Li Y, Liu Y, Zheng J, Wu B, Cui X, Xu W, Zhu C, Qiu Q, Wang K. A chromosome-level genome assembly of the pig-nosed turtle (Carettochelys insculpta). Sci Data 2024; 11:311. [PMID: 38521795 PMCID: PMC10960847 DOI: 10.1038/s41597-024-03157-8] [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: 11/28/2023] [Accepted: 03/15/2024] [Indexed: 03/25/2024] Open
Abstract
The pig-nosed turtle (Carettochelys insculpta) represents the only extant species within the Carettochelyidae family, is a unique Trionychia member fully adapted to aquatic life and currently facing endangerment. To enhance our understanding of this species and contribute to its conservation efforts, we employed high-fidelity (HiFi) and Hi-C sequencing technology to generate its genome assembly at the chromosome level. The assembly result spans 2.18 Gb, with a contig N50 of 126 Mb, encompassing 34 chromosomes that account for 99.6% of the genome. The assembly has a BUSCO score above 95% with different databases and strong collinearity with Yangtze giant softshell turtles (Rafetus swinhoei), indicating its completeness and continuity. A total of 19,175 genes and 46.86% repetitive sequences were annotated. The availability of this chromosome-scale genome represents a valuable resource for the pig-nosed turtle, providing insights into its aquatic adaptation and serving as a foundation for future turtle research.
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Affiliation(s)
- Ye Li
- Shaanxi Key Laboratory of Qinling Ecological Intelligent Monitoring and Protection, School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Yuxuan Liu
- Shaanxi Key Laboratory of Qinling Ecological Intelligent Monitoring and Protection, School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Jiangmin Zheng
- Shaanxi Key Laboratory of Qinling Ecological Intelligent Monitoring and Protection, School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Baosheng Wu
- Shaanxi Key Laboratory of Qinling Ecological Intelligent Monitoring and Protection, School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, 710072, China
- Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou, 510260, China
| | - Xinxin Cui
- Shaanxi Key Laboratory of Qinling Ecological Intelligent Monitoring and Protection, School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Wenjie Xu
- Shaanxi Key Laboratory of Qinling Ecological Intelligent Monitoring and Protection, School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Chenglong Zhu
- Shaanxi Key Laboratory of Qinling Ecological Intelligent Monitoring and Protection, School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Qiang Qiu
- Shaanxi Key Laboratory of Qinling Ecological Intelligent Monitoring and Protection, School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, 710072, China.
| | - Kun Wang
- Shaanxi Key Laboratory of Qinling Ecological Intelligent Monitoring and Protection, School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, 710072, China.
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3
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Breitenbach AT, Marroquín-Flores RA, Paitz RT, Bowden RM. Experiencing short heat waves early in development changes thermal responsiveness of turtle embryos to later heat waves. J Exp Biol 2023; 226:jeb246235. [PMID: 37661755 PMCID: PMC10560553 DOI: 10.1242/jeb.246235] [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: 06/02/2023] [Accepted: 08/17/2023] [Indexed: 09/05/2023]
Abstract
Although physiological responses to the thermal environment are most frequently investigated using constant temperatures, the incorporation of thermal variability can allow for a more accurate prediction of how thermally sensitive species respond to a rapidly changing climate. In species with temperature-dependent sex determination (TSD), developmental responses to incubation temperature are mediated by several genes involved in gonadal differentiation. Kdm6b and Dmrt1 respond to cool incubation temperatures and are associated with testis development, while FoxL2 and Cyp19A1 respond to warm incubation temperatures and are associated with ovary development. Using fluctuating incubation temperatures, we designed two studies, one investigating how conflicting thermal cues affect the timing of commitment to gonadal development, and another investigating the rapid molecular responses to conflicting thermal cues in the red-eared slider turtle (Trachemys scripta). Using gene expression as a proxy of timing of commitment to gonadal fate, results from the first study show that exposure to high amounts of conflicting thermal cues during development delays commitment to gonadal fate. Results from the second study show that Kdm6b splice variants exhibit differential responses to early heat wave exposure, but rapidly (within 2 days) recover to pre-exposure levels after the heat wave. Despite changes in the expression of Kdm6b splice variants, there was no effect on Dmrt1 expression. Collectively, these findings demonstrate how short exposures to heat early in development can change how embryos respond to heat later in development.
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Affiliation(s)
- Anthony T. Breitenbach
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
| | - Rosario A. Marroquín-Flores
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Ryan T. Paitz
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Rachel M. Bowden
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
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4
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Guo Y, Tang J, Zhuo Z, Huang J, Fu Z, Song J, Liu M, Dong Z, Wang Z. The first high-quality chromosome-level genome of Eretmochelys imbricata using HiFi and Hi-C data. Sci Data 2023; 10:604. [PMID: 37689728 PMCID: PMC10492850 DOI: 10.1038/s41597-023-02522-3] [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: 05/16/2023] [Accepted: 08/30/2023] [Indexed: 09/11/2023] Open
Abstract
Eretmochelys imbricata, a critically endangered sea turtle inhabiting tropical oceans and protected across the world, had an unknown genome sequence until now. In this study, we used HiFi reads and Hi-C technology to assemble a high-quality, chromosome-level genome of E. imbricata. The genome size was 2,138.26 Mb, with contig N50 length of 123.49 Mb and scaffold N50 of 137.21 Mb. Approximately 97.52% of the genome sequence was anchored to 28 chromosomes. A total of 20,206 protein-coding genes were predicted. We also analyzed the evolutionary relationships, gene family expansions, and positive selection of E. imbricata. Our results revealed that E. imbricata diverged from Chelonia mydas 38 million years ago and had enriched olfactory receptors and aging-related genes. Our genome will be useful for studying E. imbricata and its conservation.
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Affiliation(s)
- Yusong Guo
- Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Fisheries College, Guangdong Ocean University, Zhanjiang, 524088, China
| | - Jiao Tang
- Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Fisheries College, Guangdong Ocean University, Zhanjiang, 524088, China
| | - Zixuan Zhuo
- Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Fisheries College, Guangdong Ocean University, Zhanjiang, 524088, China
| | - Jingru Huang
- Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Fisheries College, Guangdong Ocean University, Zhanjiang, 524088, China
| | - Zhenli Fu
- Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Fisheries College, Guangdong Ocean University, Zhanjiang, 524088, China
| | - Jiahao Song
- State Key Laboratory of Marine Environmental Science and College of Ocean & Earth Sciences, Xiamen University, Xiamen, Fujian, China
| | - Min Liu
- State Key Laboratory of Marine Environmental Science and College of Ocean & Earth Sciences, Xiamen University, Xiamen, Fujian, China
| | - Zhongdian Dong
- Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Fisheries College, Guangdong Ocean University, Zhanjiang, 524088, China
| | - Zhongduo Wang
- Key Laboratory of Aquaculture in South China Sea for Aquatic Economic Animal of Guangdong Higher Education Institutes, Fisheries College, Guangdong Ocean University, Zhanjiang, 524088, China.
- Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy culture, Fisheries College, Guangdong Ocean University, Zhanjiang, 524088, China.
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5
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Genome Evolution and the Future of Phylogenomics of Non-Avian Reptiles. Animals (Basel) 2023; 13:ani13030471. [PMID: 36766360 PMCID: PMC9913427 DOI: 10.3390/ani13030471] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/13/2023] [Accepted: 01/15/2023] [Indexed: 02/01/2023] Open
Abstract
Non-avian reptiles comprise a large proportion of amniote vertebrate diversity, with squamate reptiles-lizards and snakes-recently overtaking birds as the most species-rich tetrapod radiation. Despite displaying an extraordinary diversity of phenotypic and genomic traits, genomic resources in non-avian reptiles have accumulated more slowly than they have in mammals and birds, the remaining amniotes. Here we review the remarkable natural history of non-avian reptiles, with a focus on the physical traits, genomic characteristics, and sequence compositional patterns that comprise key axes of variation across amniotes. We argue that the high evolutionary diversity of non-avian reptiles can fuel a new generation of whole-genome phylogenomic analyses. A survey of phylogenetic investigations in non-avian reptiles shows that sequence capture-based approaches are the most commonly used, with studies of markers known as ultraconserved elements (UCEs) especially well represented. However, many other types of markers exist and are increasingly being mined from genome assemblies in silico, including some with greater information potential than UCEs for certain investigations. We discuss the importance of high-quality genomic resources and methods for bioinformatically extracting a range of marker sets from genome assemblies. Finally, we encourage herpetologists working in genomics, genetics, evolutionary biology, and other fields to work collectively towards building genomic resources for non-avian reptiles, especially squamates, that rival those already in place for mammals and birds. Overall, the development of this cross-amniote phylogenomic tree of life will contribute to illuminate interesting dimensions of biodiversity across non-avian reptiles and broader amniotes.
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6
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Papa Y, Wellenreuther M, Morrison MA, Ritchie PA. Genome assembly and isoform analysis of a highly heterozygous New Zealand fisheries species, the tarakihi (Nemadactylus macropterus). G3 (BETHESDA, MD.) 2022; 13:6883520. [PMID: 36477875 PMCID: PMC9911067 DOI: 10.1093/g3journal/jkac315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 11/01/2022] [Accepted: 11/08/2022] [Indexed: 12/14/2022]
Abstract
Although being some of the most valuable and heavily exploited wild organisms, few fisheries species have been studied at the whole-genome level. This is especially the case in New Zealand, where genomics resources are urgently needed to assist fisheries management. Here, we generated 55 Gb of short Illumina reads (92× coverage) and 73 Gb of long Nanopore reads (122×) to produce the first genome assembly of the marine teleost tarakihi [Nemadactylus macropterus (Forster, 1801)], a highly valuable fisheries species in New Zealand. An additional 300 Mb of Iso-Seq reads were obtained to assist in gene annotation. The final genome assembly was 568 Mb long with an N50 of 3.37 Mb. The genome completeness was high, with 97.8% of complete Actinopterygii Benchmarking Universal Single-Copy Orthologs. Heterozygosity values estimated through k-mer counting (1.00%) and bi-allelic SNPs (0.64%) were high compared with the same values reported for other fishes. Iso-Seq analysis recovered 91,313 unique transcripts from 15,515 genes (mean ratio of 5.89 transcripts per gene), and the most common alternative splicing event was intron retention. This highly contiguous genome assembly and the isoform-resolved transcriptome will provide a useful resource to assist the study of population genomics and comparative eco-evolutionary studies in teleosts and related organisms.
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Affiliation(s)
- Yvan Papa
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Maren Wellenreuther
- Seafood Production Group, The New Zealand Institute for Plant and Food Research Limited, Nelson 7010, New Zealand,School of Biological Sciences, The University of Auckland, Auckland 1010, New Zealand
| | - Mark A Morrison
- National Institute of Water and Atmospheric Research, Auckland 1010, New Zealand
| | - Peter A Ritchie
- Corresponding author: Te Toki A Rata, Gate 7, Kelburn Parade, Wellington 6012, New Zealand.
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Çilingir FG, A'Bear L, Hansen D, Davis LR, Bunbury N, Ozgul A, Croll D, Grossen C. Chromosome-level genome assembly for the Aldabra giant tortoise enables insights into the genetic health of a threatened population. Gigascience 2022; 11:6756429. [PMID: 36251273 PMCID: PMC9553416 DOI: 10.1093/gigascience/giac090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/22/2022] [Accepted: 09/12/2022] [Indexed: 11/04/2022] Open
Abstract
Background The Aldabra giant tortoise (Aldabrachelys gigantea) is one of only two giant tortoise species left in the world. The species is endemic to Aldabra Atoll in Seychelles and is listed as Vulnerable on the International Union for Conservation of Nature Red List (v2.3) due to its limited distribution and threats posed by climate change. Genomic resources for A. gigantea are lacking, hampering conservation efforts for both wild and ex situpopulations. A high-quality genome would also open avenues to investigate the genetic basis of the species’ exceptionally long life span. Findings We produced the first chromosome-level de novo genome assembly of A. gigantea using PacBio High-Fidelity sequencing and high-throughput chromosome conformation capture. We produced a 2.37-Gbp assembly with a scaffold N50 of 148.6 Mbp and a resolution into 26 chromosomes. RNA sequencing–assisted gene model prediction identified 23,953 protein-coding genes and 1.1 Gbp of repetitive sequences. Synteny analyses among turtle genomes revealed high levels of chromosomal collinearity even among distantly related taxa. To assess the utility of the high-quality assembly for species conservation, we performed a low-coverage resequencing of 30 individuals from wild populations and two zoo individuals. Our genome-wide population structure analyses detected genetic population structure in the wild and identified the most likely origin of the zoo-housed individuals. We further identified putatively deleterious mutations to be monitored. Conclusions We establish a high-quality chromosome-level reference genome for A. gigantea and one of the most complete turtle genomes available. We show that low-coverage whole-genome resequencing, for which alignment to the reference genome is a necessity, is a powerful tool to assess the population structure of the wild population and reveal the geographic origins of ex situ individuals relevant for genetic diversity management and rewilding efforts.
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Affiliation(s)
- F Gözde Çilingir
- Correspondence address. F. Gözde Çilingir, Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland. E-mail:
| | - Luke A'Bear
- Seychelles Islands Foundation, Victoria, Republic of Seychelles
| | - Dennis Hansen
- Zoological Museum, University of Zurich, Zurich 8006, Switzerland,Indian Ocean Tortoise Alliance, Ile Cerf, Victoria, Republic of Seychelles
| | | | - Nancy Bunbury
- Seychelles Islands Foundation, Victoria, Republic of Seychelles,Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, Cornwall, TR10 9FE, UK
| | - Arpat Ozgul
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich 8057, Switzerland
| | - Daniel Croll
- Correspondence address. Christine Grossen, Eidg. Forschungsanstalt WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland. E-mail:
| | - Christine Grossen
- Correspondence address. Daniel Croll, Institute of Biology, University of Neuchâtel, Neuchâtel 2000, Switzerland. E-mail:
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Transcriptome Analyses Provide Insights into the Auditory Function in Trachemys scripta elegans. Animals (Basel) 2022; 12:ani12182410. [PMID: 36139269 PMCID: PMC9495000 DOI: 10.3390/ani12182410] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/05/2022] [Accepted: 09/09/2022] [Indexed: 11/17/2022] Open
Abstract
An auditory ability is essential for communication in vertebrates, and considerable attention has been paid to auditory sensitivity in mammals, birds, and frogs. Turtles were thought to be deaf for a long time; however, recent studies have confirmed the presence of an auditory ability in Trachemys scripta elegans as well as sex-related differences in hearing sensitivity. Earlier studies mainly focused on the morphological and physiological functions of the hearing organ in turtles; thus, the gene expression patterns remain unclear. In this study, 36 transcriptomes from six tissues (inner ear, tympanic membrane, brain, eye, lung, and muscle) were sequenced to explore the gene expression patterns of the hearing system in T. scripta elegans. A weighted gene co-expression network analysis revealed that hub genes related to the inner ear and tympanic membrane are involved in development and signal transduction. Moreover, we identified six differently expressed genes (GABRA1, GABRG2, GABBR2, GNAO1, SLC38A1, and SLC12A5) related to the GABAergic synapse pathway as candidate genes to explain the differences in sexually dimorphic hearing sensitivity. Collectively, this study provides a critical foundation for genetic research on auditory functions in turtles.
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Breitenbach AT, Bowden RM, Paitz RT. Effects of Constant and Fluctuating Temperatures on Gene Expression During Gonadal Development. Integr Comp Biol 2022; 62:21-29. [PMID: 35325145 DOI: 10.1093/icb/icac011] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
There is ample research demonstrating that temperature can have complex effects on biological processes, including the timing of when organisms respond to temperature; some responses occur rapidly while others require an extended exposure time. However, most of what we know about temperature effects comes from studies using constant temperature conditions, which are not reflective of natural, fluctuating temperatures. Species with temperature-dependent sex determination (TSD) present an ideal system to study the temporal aspects of the temperature response because prior research has established a number of temperature-responsive genes involved in TSD, albeit under constant temperatures. To investigate potential differences in timing of sexual development between constant and fluctuating incubation temperatures, we exposed Trachemys scripta embryos to two conditions that produce males (constant 26 °C and 26 ± 3 °C) and two that produce females (constant 31 °C and 31 ± 3 °C) and sampled embryonic gonads for gene expression analysis via qPCR. We analyzed three genes involved in testis differentiation (Kdm6b, Dmrt1, and Sox9) and two genes involved in ovary differentiation (Foxl2 and Cyp19A1). Results show that Kdm6b expression was significantly lower under fluctuating temperatures compared to constant temperatures. Foxl2 and Cyp19A1 expression were also lower under fluctuating temperatures, but not at all stages of development. These results suggest that constant temperatures caused increases in both Foxl2 and Cyp19A1 expression earlier (developmental stage 20) than fluctuating temperatures (stages 22-23). Dmrt1 and Sox9 expression did not differ between constant and fluctuating temperatures. These results highlight that not all genes in a temperature-dependent process respond to temperature in the same manner. Whether there are functional consequences of this variation remains to be determined.
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Affiliation(s)
| | - Rachel M Bowden
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Ryan T Paitz
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
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10
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Koochekian N, Ascanio A, Farleigh K, Card DC, Schield DR, Castoe TA, Jezkova T. A chromosome-level genome assembly and annotation of the desert horned lizard, Phrynosoma platyrhinos, provides insight into chromosomal rearrangements among reptiles. Gigascience 2022; 11:6521878. [PMID: 35134927 PMCID: PMC8848323 DOI: 10.1093/gigascience/giab098] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 09/27/2021] [Accepted: 12/15/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The increasing number of chromosome-level genome assemblies has advanced our knowledge and understanding of macroevolutionary processes. Here, we introduce the genome of the desert horned lizard, Phrynosoma platyrhinos, an iguanid lizard occupying extreme desert conditions of the American southwest. We conduct analysis of the chromosomal structure and composition of this species and compare these features across genomes of 12 other reptiles (5 species of lizards, 3 snakes, 3 turtles, and 1 bird). FINDINGS The desert horned lizard genome was sequenced using Illumina paired-end reads and assembled and scaffolded using Dovetail Genomics Hi-C and Chicago long-range contact data. The resulting genome assembly has a total length of 1,901.85 Mb, scaffold N50 length of 273.213 Mb, and includes 5,294 scaffolds. The chromosome-level assembly is composed of 6 macrochromosomes and 11 microchromosomes. A total of 20,764 genes were annotated in the assembly. GC content and gene density are higher for microchromosomes than macrochromosomes, while repeat element distributions show the opposite trend. Pathway analyses provide preliminary evidence that microchromosome and macrochromosome gene content are functionally distinct. Synteny analysis indicates that large microchromosome blocks are conserved among closely related species, whereas macrochromosomes show evidence of frequent fusion and fission events among reptiles, even between closely related species. CONCLUSIONS Our results demonstrate dynamic karyotypic evolution across Reptilia, with frequent inferred splits, fusions, and rearrangements that have resulted in shuffling of chromosomal blocks between macrochromosomes and microchromosomes. Our analyses also provide new evidence for distinct gene content and chromosomal structure between microchromosomes and macrochromosomes within reptiles.
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Affiliation(s)
| | - Alfredo Ascanio
- Department of Biology, Miami University, Oxford, OH 45056, USA
| | - Keaka Farleigh
- Department of Biology, Miami University, Oxford, OH 45056, USA
| | - Daren C Card
- Department of Organismic & Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.,Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, USA
| | - Drew R Schield
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA
| | - Todd A Castoe
- Department of Biology, University of Texas at Arlington, Arlington, TX 76019, USA
| | - Tereza Jezkova
- Department of Biology, Miami University, Oxford, OH 45056, USA
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11
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Liu J, Liu S, Zheng K, Tang M, Gu L, Young J, Wang Z, Qiu Y, Dong J, Gu S, Xiong L, Zhou R, Nie L. Chromosome-level genome assembly of the Chinese three-keeled pond turtle (Mauremys reevesii) provides insights into freshwater adaptation. Mol Ecol Resour 2021; 22:1596-1605. [PMID: 34845835 DOI: 10.1111/1755-0998.13563] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 11/19/2021] [Accepted: 11/23/2021] [Indexed: 11/27/2022]
Abstract
Mauremys reevesii is an endangered freshwater turtle that symbolizes longevity in Chinese culture. Despite its importance, genetic studies of this species remain limited, with no genomic sequence reported to date. Here, we report a high-quality, chromosome-level genomic sequence of M. reevesii obtained using a combination of Nanopore and Hi-C sequencing technologies. The 2.37 Gb M. reevesii genome was assembled from a total of ~226.80 Gb of Nanopore sequencing data. The M. reevesii genome contig N50 is 34.73 Mb, the highest value in published turtle genomes. In total, 18,238 genes were functionally annotated. The contigs were clustered and ordered onto 27 pseudochromosomes covering ~96.55% of the genome assembled with Hi-C data. To explore genome evolution, synteny analysis was performed between M. reevesii (freshwater turtle) and Gopherus evgoodei (terrestrial turtle) genomes. In general, each chromosome of M. reevesii corresponded to one chromosome of Gopherus evgoodei, but some interchromosomal rearrangements occurred between the two species based on the assembled genomes. These interchromosomal rearrangements were further confirmed by mapping of the long-read nanopore data to the assembly. The reconstructed demographic history showed varied effective population size among freshwater, marine and terrestrial turtles. We also discovered expansion of genes related to the innate immune system in M. reevesii that may provide defence against freshwater pathogens. The high-quality genomic sequence provides a valuable genetic resource for further studies of genetics and genome evolution in turtles.
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Affiliation(s)
- Jianjun Liu
- Provincial Key Laboratory of the Conservation and Exploitation Research of Biological Resources in Anhui, College of Life Science, Anhui Normal University, Wuhu, China.,Department of Biology and Microbiology, South Dakota State University, Brookings, South Dakota, USA
| | - Siqi Liu
- Provincial Key Laboratory of the Conservation and Exploitation Research of Biological Resources in Anhui, College of Life Science, Anhui Normal University, Wuhu, China
| | - Kai Zheng
- Provincial Key Laboratory of the Conservation and Exploitation Research of Biological Resources in Anhui, College of Life Science, Anhui Normal University, Wuhu, China
| | - Min Tang
- Provincial Key Laboratory of the Conservation and Exploitation Research of Biological Resources in Anhui, College of Life Science, Anhui Normal University, Wuhu, China
| | - Liping Gu
- Department of Biology and Microbiology, South Dakota State University, Brookings, South Dakota, USA
| | - James Young
- Department of Biology and Microbiology, South Dakota State University, Brookings, South Dakota, USA
| | - Ziming Wang
- Provincial Key Laboratory of the Conservation and Exploitation Research of Biological Resources in Anhui, College of Life Science, Anhui Normal University, Wuhu, China
| | - Yeyan Qiu
- Department of Biology and Microbiology, South Dakota State University, Brookings, South Dakota, USA
| | - Jinxiu Dong
- Provincial Key Laboratory of the Conservation and Exploitation Research of Biological Resources in Anhui, College of Life Science, Anhui Normal University, Wuhu, China
| | | | | | - Ruanbao Zhou
- Department of Biology and Microbiology, South Dakota State University, Brookings, South Dakota, USA
| | - Liuwang Nie
- Provincial Key Laboratory of the Conservation and Exploitation Research of Biological Resources in Anhui, College of Life Science, Anhui Normal University, Wuhu, China
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12
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Martin BT, Chafin TK, Douglas MR, Douglas ME. ClineHelpR: an R package for genomic cline outlier detection and visualization. BMC Bioinformatics 2021; 22:501. [PMID: 34656096 PMCID: PMC8520269 DOI: 10.1186/s12859-021-04423-x] [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: 07/27/2021] [Accepted: 10/04/2021] [Indexed: 11/30/2022] Open
Abstract
Background Patterns of multi-locus differentiation (i.e., genomic clines) often extend broadly across hybrid zones and their quantification can help diagnose how species boundaries are shaped by adaptive processes, both intrinsic and extrinsic. In this sense, the transitioning of loci across admixed individuals can be contrasted as a function of the genome-wide trend, in turn allowing an expansion of clinal theory across a much wider array of biodiversity. However, computational tools that serve to interpret and consequently visualize ‘genomic clines’ are limited, and users must often write custom, relatively complex code to do so. Results Here, we introduce the ClineHelpR R-package for visualizing genomic clines and detecting outlier loci using output generated by two popular software packages, bgc and Introgress. ClineHelpR bundles both input generation (i.e., filtering datasets and creating specialized file formats) and output processing (e.g., MCMC thinning and burn-in) with functions that directly facilitate interpretation and hypothesis testing. Tools are also provided for post-hoc analyses that interface with external packages such as ENMeval and RIdeogram. Conclusions Our package increases the reproducibility and accessibility of genomic cline methods, thus allowing an expanded user base and promoting these methods as mechanisms to address diverse evolutionary questions in both model and non-model organisms. Furthermore, the ClineHelpR extended functionality can evaluate genomic clines in the context of spatial and environmental features, allowing users to explore underlying processes potentially contributing to the observed patterns and helping facilitate effective conservation management strategies.
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Affiliation(s)
- Bradley T Martin
- Arkansas Conservation and Molecular Ecology Laboratory, Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA. .,University of Arkansas Global Campus, Fayetteville, AR, 72701, USA.
| | - Tyler K Chafin
- Arkansas Conservation and Molecular Ecology Laboratory, Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA.,Ecology and Evolutionary Biology Department, University of Colorado, Boulder, CO, USA
| | - Marlis R Douglas
- Arkansas Conservation and Molecular Ecology Laboratory, Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA
| | - Michael E Douglas
- Arkansas Conservation and Molecular Ecology Laboratory, Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA
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13
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Kratochvíl L, Gamble T, Rovatsos M. Sex chromosome evolution among amniotes: is the origin of sex chromosomes non-random? Philos Trans R Soc Lond B Biol Sci 2021; 376:20200108. [PMID: 34304592 PMCID: PMC8310715 DOI: 10.1098/rstb.2020.0108] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2021] [Indexed: 12/29/2022] Open
Abstract
Sex chromosomes are a great example of a convergent evolution at the genomic level, having evolved dozens of times just within amniotes. An intriguing question is whether this repeated evolution was random, or whether some ancestral syntenic blocks have significantly higher chance to be co-opted for the role of sex chromosomes owing to their gene content related to gonad development. Here, we summarize current knowledge on the evolutionary history of sex determination and sex chromosomes in amniotes and evaluate the hypothesis of non-random emergence of sex chromosomes. The current data on the origin of sex chromosomes in amniotes suggest that their evolution is indeed non-random. However, this non-random pattern is not very strong, and many syntenic blocks representing putatively independently evolved sex chromosomes are unique. Still, repeatedly co-opted chromosomes are an excellent model system, as independent co-option of the same genomic region for the role of sex chromosome offers a great opportunity for testing evolutionary scenarios on the sex chromosome evolution under the explicit control for the genomic background and gene identity. Future studies should use these systems more to explore the convergent/divergent evolution of sex chromosomes. This article is part of the theme issue 'Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part II)'.
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Affiliation(s)
- Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, Prague, Czech Republic
| | - Tony Gamble
- Department of Biological Sciences, Marquette University, Milwaukee, WI, USA
- Bell Museum of Natural History, University of Minnesota, Saint Paul, MN, USA
- Milwaukee Public Museum, Milwaukee, WI, USA
| | - Michail Rovatsos
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, Prague, Czech Republic
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14
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Van Dam MH, Cabras AA, Henderson JB, Rominger AJ, Pérez Estrada C, Omer AD, Dudchenko O, Lieberman Aiden E, Lam AW. The Easter Egg Weevil (Pachyrhynchus) genome reveals syntenic patterns in Coleoptera across 200 million years of evolution. PLoS Genet 2021; 17:e1009745. [PMID: 34460814 PMCID: PMC8432895 DOI: 10.1371/journal.pgen.1009745] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 09/10/2021] [Accepted: 07/27/2021] [Indexed: 01/01/2023] Open
Abstract
Patterns of genomic architecture across insects remain largely undocumented or decoupled from a broader phylogenetic context. For instance, it is unknown whether translocation rates differ between insect orders. We address broad scale patterns of genome architecture across Insecta by examining synteny in a phylogenetic framework from open-source insect genomes. To accomplish this, we add a chromosome level genome to a crucial lineage, Coleoptera. Our assembly of the Pachyrhynchus sulphureomaculatus genome is the first chromosome scale genome for the hyperdiverse Phytophaga lineage and currently the largest insect genome assembled to this scale. The genome is significantly larger than those of other weevils, and this increase in size is caused by repetitive elements. Our results also indicate that, among beetles, there are instances of long-lasting (>200 Ma) localization of genes to a particular chromosome with few translocation events. While some chromosomes have a paucity of translocations, intra-chromosomal synteny was almost absent, with gene order thoroughly shuffled along a chromosome. This large amount of reshuffling within chromosomes with few inter-chromosomal events contrasts with patterns seen in mammals in which the chromosomes tend to exchange larger blocks of material more readily. To place our findings in an evolutionary context, we compared syntenic patterns across Insecta in a phylogenetic framework. For the first time, we find that synteny decays at an exponential rate relative to phylogenetic distance. Additionally, there are significant differences in decay rates between insect orders, this pattern was not driven by Lepidoptera alone which has a substantially different rate.
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Affiliation(s)
- Matthew H. Van Dam
- Entomology Department, Institute for Biodiversity Science and Sustainability, California Academy of Sciences, San Francisco, California, United States of America
- Center for Comparative Genomics, Institute for Biodiversity Science and Sustainability, California Academy of Science, San Francisco, California, United States of America
| | - Analyn Anzano Cabras
- Coleoptera Research Center, Institute for Biodiversity and Environment, University of Mindanao, Matina, Davao City, Philippines
| | - James B. Henderson
- Center for Comparative Genomics, Institute for Biodiversity Science and Sustainability, California Academy of Science, San Francisco, California, United States of America
| | - Andrew J. Rominger
- School of Biology and Ecology, University of Maine, Orono, Maine, United States of America
| | - Cynthia Pérez Estrada
- The Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Arina D. Omer
- The Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Olga Dudchenko
- The Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Erez Lieberman Aiden
- The Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Athena W. Lam
- Center for Comparative Genomics, Institute for Biodiversity Science and Sustainability, California Academy of Science, San Francisco, California, United States of America
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15
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Marroquín-Flores RA, Bowden RM, Paitz RT. Brief exposure to warm temperatures reduces intron retention in Kdm6b in a species with temperature-dependent sex determination. Biol Lett 2021; 17:20210167. [PMID: 34102073 PMCID: PMC8187015 DOI: 10.1098/rsbl.2021.0167] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/13/2021] [Indexed: 12/14/2022] Open
Abstract
Animals with temperature-dependent sex determination (TSD) respond to thermal cues during early embryonic development to trigger gonadal differentiation. TSD has primarily been studied using constant temperature incubations, where embryos are exposed to constant male- or female-producing temperatures, and these studies have identified genes that display sex-specific expression in response to incubation temperature. Kdm6b, a histone demethylase gene, has received specific attention as it is among the initial genes to respond to incubation temperature and is necessary for testis development. Interestingly, Kdm6b retains an intron when eggs are incubated at a constant male-producing temperature, but the role of thermal variability in this developmental process is relatively understudied. Species with TSD regularly experience thermal cues that fluctuate between male- and female-producing temperatures throughout development but it is unclear how Kdm6b responds to such variable temperatures. In this study, we investigate temperature-sensitive splicing in Kdm6b by exposing embryos to male- and female-producing thermal conditions. We show a rapid decrease in levels of the intron retaining transcript of Kdm6b upon exposure to female-producing conditions. These results demonstrate that, under ecologically relevant conditions, temperature-sensitive splicing can differentially regulate genes critical to TSD.
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Affiliation(s)
| | - Rachel M. Bowden
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Ryan T. Paitz
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
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Abstract
Syntenies are genomic segments of consecutive genes identified by a certain conservation in gene content and order. The notion of conservation may vary from one definition to another, the more constrained requiring identical gene contents and gene orders, while more relaxed definitions just require a certain similarity in gene content, and not necessarily in the same order. Regardless of the way they are identified, the goal is to characterize homologous genomic regions, i.e., regions deriving from a common ancestral region, reflecting a certain gene co-evolution that can enlighten important functional properties. In addition of being able to identify them, it is also necessary to infer the evolutionary history that has led from the ancestral segment to the extant ones. In this field, most algorithmic studies address the problem of inferring rearrangement scenarios explaining the disruption in gene order between segments with the same gene content, some of them extending the evolutionary model to gene insertion and deletion. However, syntenies also evolve through other events modifying their content in genes, such as duplications, losses or horizontal gene transfers, i.e., the movement of genes from one species to another. Although the reconciliation approach between a gene tree and a species tree addresses the problem of inferring such events for single-gene families, little effort has been dedicated to the generalization to segmental events and to syntenies. This paper reviews some of the main algorithmic methods for inferring ancestral syntenies and focus on those integrating both gene orders and gene trees.
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Vassetzky NS, Kosushkin SA, Korchagin VI, Ryskov AP. New Ther1-derived SINE Squam3 in scaled reptiles. Mob DNA 2021; 12:10. [PMID: 33752750 PMCID: PMC7983390 DOI: 10.1186/s13100-021-00238-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/25/2021] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND SINEs comprise a significant part of animal genomes and are used to study the evolution of diverse taxa. Despite significant advances in SINE studies in vertebrates and higher eukaryotes in general, their own evolution is poorly understood. RESULTS We have discovered and described in detail a new Squam3 SINE specific for scaled reptiles (Squamata). The subfamilies of this SINE demonstrate different distribution in the genomes of squamates, which together with the data on similar SINEs in the tuatara allowed us to propose a scenario of their evolution in the context of reptilian evolution. CONCLUSIONS Ancestral SINEs preserved in small numbers in most genomes can give rise to taxa-specific SINE families. Analysis of this aspect of SINEs can shed light on the history and mechanisms of SINE variation in reptilian genomes.
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Affiliation(s)
- Nikita S Vassetzky
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334, Russia.
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia.
| | - Sergei A Kosushkin
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Vitaly I Korchagin
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334, Russia
| | - Alexey P Ryskov
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334, Russia
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18
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Cytogenetic Analysis of the Asian Box Turtles of the Genus Cuora (Testudines, Geoemydidae). Genes (Basel) 2021; 12:genes12020156. [PMID: 33503936 PMCID: PMC7911423 DOI: 10.3390/genes12020156] [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: 12/27/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 11/18/2022] Open
Abstract
The Asian box turtle genus Cuora currently comprises 13 species with a wide distribution in Southeast Asia, including China and the islands of Indonesia and Philippines. The populations of these species are rapidly declining due to human pressure, including pollution, habitat loss, and harvesting for food consumption. Notably, the IUCN Red List identifies almost all species of the genus Cuora as Endangered (EN) or Critically Endangered (CR). In this study, we explore the karyotypes of 10 Cuora species with conventional (Giemsa staining, C-banding, karyogram reconstruction) and molecular cytogenetic methods (in situ hybridization with probes for rDNA loci and telomeric repeats). Our study reveals a diploid chromosome number of 2n = 52 chromosomes in all studied species, with karyotypes of similar chromosomal morphology. In all examined species, rDNA loci are detected at a single medium-sized chromosome pair and the telomeric repeats are restricted to the expected terminal position across all chromosomes. In contrast to a previous report, sex chromosomes are neither detected in Cuoragalbinifrons nor in any other species. Therefore, we assume that these turtles have either environmental sex determination or genotypic sex determination with poorly differentiated sex chromosomes. The conservation of genome organization could explain the numerous observed cases of interspecific hybridization both within the genus Cuora and across geoemydid turtles.
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19
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Martin BT, Douglas MR, Chafin TK, Placyk JS, Birkhead RD, Phillips CA, Douglas ME. Contrasting signatures of introgression in North American box turtle (
Terrapene
spp.) contact zones. Mol Ecol 2020; 29:4186-4202. [DOI: 10.1111/mec.15622] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 08/19/2020] [Accepted: 08/24/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Bradley T. Martin
- Department of Biological Sciences University of Arkansas Fayetteville AR USA
| | - Marlis R. Douglas
- Department of Biological Sciences University of Arkansas Fayetteville AR USA
| | - Tyler K. Chafin
- Department of Biological Sciences University of Arkansas Fayetteville AR USA
| | - John S. Placyk
- Department of Biology University of Texas Tyler TX USA
- Science Division Trinity Valley Community College Athens TX USA
| | | | - Christopher A. Phillips
- Illinois Natural History Survey Prairie Research Institute University of Illinois Champaign IL USA
| | - Michael E. Douglas
- Department of Biological Sciences University of Arkansas Fayetteville AR USA
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20
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Karyotypic Evolution of Sauropsid Vertebrates Illuminated by Optical and Physical Mapping of the Painted Turtle and Slider Turtle Genomes. Genes (Basel) 2020; 11:genes11080928. [PMID: 32806747 PMCID: PMC7464131 DOI: 10.3390/genes11080928] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 07/25/2020] [Accepted: 07/31/2020] [Indexed: 02/07/2023] Open
Abstract
Recent sequencing and software enhancements have advanced our understanding of the evolution of genomic structure and function, especially addressing novel evolutionary biology questions. Yet fragmentary turtle genome assemblies remain a challenge to fully decipher the genetic architecture of adaptive evolution. Here, we use optical mapping to improve the contiguity of the painted turtle (Chrysemys picta) genome assembly and use de novo fluorescent in situ hybridization (FISH) of bacterial artificial chromosome (BAC) clones, BAC-FISH, to physically map the genomes of the painted and slider turtles (Trachemys scripta elegans). Optical mapping increased C. picta's N50 by ~242% compared to the previous assembly. Physical mapping permitted anchoring ~45% of the genome assembly, spanning 5544 genes (including 20 genes related to the sex determination network of turtles and vertebrates). BAC-FISH data revealed assembly errors in C. picta and T. s. elegans assemblies, highlighting the importance of molecular cytogenetic data to complement bioinformatic approaches. We also compared C. picta's anchored scaffolds to the genomes of other chelonians, chicken, lizards, and snake. Results revealed a mostly one-to-one correspondence between chromosomes of painted and slider turtles, and high homology among large syntenic blocks shared with other turtles and sauropsids. Yet, numerous chromosomal rearrangements were also evident across chelonians, between turtles and squamates, and between avian and non-avian reptiles.
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