Abstract
The metallothionein (MT) gene superfamily consists of metal-binding proteins involved in various metal detoxification and storage mechanisms. The evolution of this gene family in vertebrates has mostly been studied in mammals using sparse taxon or gene sampling. Genomic databases and available data on MT protein function and expression allow a better understanding of the evolution and functional divergence of the different MT types. We recovered 77 MT coding sequences from 20 representative vertebrates with annotated complete genomes. We found multiple MT genes, also in reptiles, which were thought to have only one MT type. Phylogenetic and synteny analyses indicate the existence of a eutherian MT1 and MT2, a tetrapod MT3, an amniote MT4, and fish MT. The optimal gene-tree/species-tree reconciliation analyses identified the best root in the fish clade. Functional analyses reveal variation in hydropathic index among protein domains, likely correlated with their distinct flexibility and metal affinity. Analyses of functional divergence identified amino acid sites correlated with functional divergence among MT types. Uncovering the number of genes and sites possibly correlated with functional divergence will help to design cost-effective MT functional and gene expression studies. This will permit further understanding of the distinct roles and specificity of these proteins and to properly target specific MT for different types of functional studies. Therefore, this work presents a critical background on the molecular evolution and functional divergence of vertebrate MTs to carry out further detailed studies on the relationship between heavy metal metabolism and tolerances among vertebrates.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Andreani G, Santoro M, Cottignoli S, Fabbri M, Carpenè E, Isani G (2007) Metal distribution and metallothionein in loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtles. Sci Total Environ 390:287–294. doi:10.1016/j.scitotenv.2007.09.014
Anisimova M, Gascuel O (2006) Approximate likelihood-ratio test for branches: a fast, accurate, and powerful alternative. Syst Biol 55:539–552
Bargelloni L, Scudiero R, Parisi E, Carginale V, Capasso C, Patarnello T (1999) Metallothioneins in antarctic fish: evidence for independent duplication and gene conversion. Mol Biol Evol 16:885–897
Binz P-A, Kägi JHR (1999) Classification of metallothionein. http://www.bioc.uzh.ch/mtpage/classif.html. Accessed 6 Feb 2013
Blindauer CA, Leszczyszyn OI (2010) Metallothioneins: unparalleled diversity in structures and functions for metal ion homeostasis and more. Nat Prod Rep 27:720–741. doi:10.1039/B906685N
Braun W, Vašák M, Robbins AH, Stout CD, Wagner G, Kägi JHR, Wüthrich K (1992) Comparison of the NMR solution structure and the X-ray crystal structure of rat metallothionein-2. Proc Natl Acad Sci USA 89:10124–10128
Brown CJ, Todd KM, Rosenzweig RF (1998) Multiple duplications of yeast hexose transport genes in response to selection in a glucose-limited environment. Mol Biol Evol 15:931–942
Capasso C, Carginale V, Scudiero R, Crescenzi O, Spadaccini R, Temussi PA, Parisi E (2003) Phylogenetic divergence of fish and mammalian metallothionein: relationships with structural diversification and organismal temperature. J Mol Evol 57:S250–S257. doi:10.1007/s00239-003-0034-z
Capasso C, Carginale V, Crescenzi O, Di Maro D, Spadaccini R, Temussi PA, Parisi E (2005) Structural and functional studies of vertebrate metallothioneins: cross-talk between domains in the absence of physical contact. Biochem J 391:95–103. doi:10.1042/BJ20050335
Capdevila M, Atrian S (2011) Metallothionein protein evolution: a miniassay. J Biol Inorg Chem 16:977–989. doi:10.1007/s00775-011-0798-3
Carpenè E, Andreani G, Isani G (2007) Metallothionein functions and structural characteristics. J Trace Elem Med Biol 21:35–39. doi:10.1016/j.jtemb.2007.09.011
Chang D, Duda TF (2012) Extensive and continuous duplication facilitates rapid evolution and diversification of gene families. Mol Biol Evol 29:2019–2029. doi:10.1093/molbev/mss068
Chen K, Durand D, Farach-Colton M (2000) NOTUNG: a program for dating gene duplications and optimizing gene family trees. J Comput Biol 7:429–447. doi:10.1089/106652700750050871
Chiari Y, Cahais V, Galtier N, Delsuc F (2012) Phylogenomic analyses support the position of turtles as the sister group of birds and crocodiles (Archosauria). BMC Biol 10:65. doi:10.1186/1741-7007-10-65
Dallinger R, Höckner M (2013) Evolutionary concepts in ecotoxicology: tracing the genetic background of differential cadmium sensitivities in invertebrate lineages. Ecotoxicology 22:767–778. doi:10.1007/s10646-013-1071-z
Dallinger R, Berger B, Hunziker P, Kagi JH (1997) Metallothionein in snail Cd and Cu metabolism. Nature 388:237–238
Darriba D, Taboada GL, Doallo R, Posada D (2011) ProtTest 3: fast selection of best-fit models of protein evolution. Bioinformatics 27:1164–1165. doi:10.1093/bioinformatics/btr088
Darriba D, Taboada GL, Doallo R, Posada D (2012) jModelTest 2: more models, new heuristics and parallel computing. Nat Methods 9:772. doi:10.1038/nmeth.2109
Davis SR, Cousins RJ (2000) Recent advances in nutritional sciences metallothionein expression in animals: a physiological perspective on function. J Nutr 1:1085–1088
Demuth JP, De Bie T, Stajich JE, Cristianini N, Hahn MW (2006) The evolution of mammalian gene families. PLoS ONE 1(1):e85. doi:10.1371/journal.pone.0000085
Doyon J-P, Ranwez V, Daubin V, Berry V (2011) Models, algorithms and programs for phylogeny reconciliation. Brief Bioinf 12:392–400. doi:10.1093/bib/bbr045
Durand D, Halldórsson BV, Vernot B (2006) A hybrid micro-macroevolutionary approach to gene tree reconstruction. J Comput Biol 13:320–335. doi:10.1089/cmb.2006.13.320
Ensembl database (2013) www.ensembl.org. Accessed 2 May 2013
Flicek P, Amode MR, Barrell D, Beal K, Brent S, Chen Y, Claphan P, Coates G, Fairley S, Fitzgerald S, Gordon L et al (2011) Ensembl 2011. Nucleic Acids Res 39:D800–D806. doi:10.1093/nar/gkq1064
Force A, Lynch M, Pickett FB, Amores A, Yan YL, Postlethwait J (1999) Preservation of duplicate genes by complementary, degenerative mutations. Genetics 151:1531–1545
Fowler BA, Hildebrand CE, Kojima Y, Webb M (1987) Nomenclature of metallothionein. Exp Suppl 52:19–22
Garrett SH, Somji S, Todd JH, Sens MA, Sens DA (1998) Differential expression of human metallothionein isoform I mRNA in human proximal tubule cells exposed to metals. Environ Health Perspect 106:825–831
GRAVY Calculator (2013) www.gravy-calculator.de. Accessed 11 Oct 2013
Gu X (1999) Statistical methods for testing functional divergence after gene duplication. Mol Biol Evol 16:1664–1674
Gu X (2001) Maximum-likelihood approach for gene family evolution under functional divergence. Mol Biol Evol 18:453–464
Gu X (2006) A simple statistical method for estimating type-II (cluster-specific) functional divergence of protein sequences. Mol Biol Evol 23:1937–1945. doi:10.1093/molbev/msl056
Gu X, Vander Velden K (2002) DIVERGE: phylogeny-based analysis for functional-structural divergence of a protein family. Bioinformatics 18:500–501. doi:10.1093/bioinformatics/18.3.50
Guindon S, Gascuel O (2003) A simple, fast, and accurate algorithm to estimate large phylogenies by maximum likelihood. Syst Biol 52:696–704. doi:10.1080/10635150390235520
Guindon S, Dufayard J-F, Lefort V, Anisimova M, Hordijk W, Gascuel O (2010) New algorithms and methods to estimate maximum-likelihood phylogenies: assessing the performance of PhyML 3.0. Syst Biol 59:307–321. doi:10.1093/sysbio/syq010
Guirola M, Pérez-Rafael S, Capdevila M, Palacios O, Atrian S (2012) Metal dealing at the origin of the Chordata phylum: the metallothionein system and metal overload response in Amphioxus. PLoS ONE 7(8):e43299. doi:10.1371/journal.pone.0043299
Hidalgo J, Chung R, Penkowa M, Vašák M (2009) Structure and function of vertebrate metallothioneins. Met Ions Life Sci 5:279–317
Howe K, Clark MD, Torroja CF, Torrance J, Berthelot C, Muffatto M, Collins JE, Humphray S, McLaren K, Matthews L et al (2013) The zebrafish reference genome sequence and its relationship to the human genome. Nature 496:498–503. doi:10.1038/nature12111
Huelsenbeck JP, Ronquist F (2001) MRBAYES: Bayesian inference of phylogenetic trees. Bioinformatics 17:754–755
Junqueira-de-Azevedo IDLM, Ho PL (2002) A survey of gene expression and diversity in the venom glands of the pitviper snake Bothrops insularis through the generation of expressed1 sequence tags (ESTs). Gene 299:279–291. doi:10.1016/S0378-1119(02)01080-6
Kent WJ (2002) BLAT—The BLAST-like alignment tool. Genome Res 12:656–664. doi:10.1101/gr.229202
Kim M, Park K, Park JY, Kwak I-S (2013) Heavy metal contamination and metallothionein mRNA in blood and feathers of black-tailed gulls (Larus crassirostris) from South Korea. Environ Monit Assess 185:2221–2230. doi:10.1007/s10661-012-2703-0
Kondrashov FA (2012) Gene duplication as a mechanism of genomic adaptation to a changing environment. Proc R Soc 279:5048–5057. doi:10.1098/rspb 2012.1108
Kondrashov FA, Rogozin IB, Wolf YI, Koonin EV (2002) Selection in the evolution of gene duplications. Genome Biol 3:1–0008. doi:10.1186/gb-2002-3-2-research0008
Koonin EV (2009) Darwinian evolution in the light of genomics. Nucleic Acids Res 37:1011–1034. doi:10.1093/nar/gkp089
Kyte J, Doolittle RF (1982) A simple method for displaying the hydropathic character of a protein. J Mol Biol 157:105–132
Lenormand T, Guillemaud T, Bourguet D, Raymond M (1998) Appearance and sweep of a gene duplication: adaptive response and potential for new functions in the mosquito Culex pipiens. Evolution 52:1705–1712
Li W, Luo C, Wu C (1985) A new method for estimating synonymous and nonsynonymous rates of nucleotide substitution considering the relative likelihood of nucleotide and codon changes. Mol Biol Evol 2:150–174
Li C, Ortí G, Zhang G, Lu G (2007) A practical approach to phylogenomics: the phylogeny of ray-finned fish (Actinopterygii) as a case study. BMC Evol Biol 7:44. doi:10.1186/1471-2148-7-44
Lichtarge O, Bourne HR, Cohen FE (1996) An evolutionary trace method defines binding surfaces common to protein families. J Mol Biol 257:342–358
Louis A, Muffato M, Roest Crollius H (2012) Genomicus: five genome browsers for comparative genomics in eukaryota. Nucleic Acids Res 41(D1):D700–D705. doi:10.1093/nar/gks1156
McEwen GK, Woolfe A, Goode D, Vavouri T, Callaway H, Elgar G (2006) Ancient duplicated conserved noncoding elements in vertebrates: a genomic and functional analysis. Genome Res 16:451–465. doi:10.1101/gr.4143406
Miles AT, Hawksworth GM, Beattie JH, Rodilla V (2000) Induction, regulation, degradation, and biological significance of mammalian metallothioneins. Crit Ver Biochem Mol Biol 35:35–70
Moleirinho A, Carneiro J, Matthiesen R, Silva RM, Amorim A, Azevedo L (2011) Gains, losses and changes of function after gene duplication: study of the metallothionein family. PLoS ONE 6(4):e18487. doi:10.1371/journal.pone.0018487
Muffato M, Louis A, Poisnel C-E, Roest Crollius H (2010) Genomicus: a database and a browser to study gene synteny in modern and ancestral genomes. Bioinformatics 26(8):1119–1121. doi:10.1093/bioinformatics/btq079
Nam D-H, Kim E-Y, Iwata H, Tanabe S (2007) Molecular characterization of two metallothionein isoforms in avian species: evolutionary history, tissue distribution profile, and expression associated with metal accumulation. Comp Biochem Physiol 145:295–305. doi:10.1016/j.cbpc.2006.10.012
NCBI database (2013). www.ncbi.nlm.nih.gov. Accessed 5 June 2013
Nordberg GF (1989) Modulation of metal toxicity by metallothionein. Biol Trace Elem Res 21:131–135
Nordberg M, Kojima Y (1979) Metallothionein. In: Kägi JWR, Nordberg M (eds) Proceedings of the first international meeting on metallotionein and other low molecular weight metal-binding proteins. Birkhäuser, Switzerland, pp 41–117
Nordberg M, Nordberg GF (2009) Metallothioneins: historical development and overview. In: Sigel A, Sigel H, Sigel RKO (eds) Metal ions in life sciences. The Royal Society of Chemistry, Cambridge, UK, pp 1–29
Nylander J, Ronquist F, Huelsenbeck J, Nieves-Aldrey J (2004) Bayesian phylogenetic analysis of combined data. Syst Biol 53:47–67. doi:10.1080/10635150490264699
Ohno S (1970) Evolution by gene duplication. Springer, London
Palacios O, Atrian S, Capdevila M (2011) Zn- and Cu-thioneins: a functional classification for metallothioneins? J Biol Inorg Chem 16:991–1009. doi:10.1007/s00775-011-0827-2
Palmiter RD (1998) The elusive function of metallothioneins. Proc Natl Acad Sci 95:8428–8430
Prince VE, Pickett FB (2002) Splitting pairs: the diverging fates of duplicated genes. Nat Rev Gen 3:827–837
Protein Hydrophobicity Plots Generator (2013) www.vivo.colostate.edu/molkit/hydropathy. Accessed 2 May 2013
Pruitt KD, Harrow J, Harte RA, Wallin C, Diekhans M, Maglott DR, Searle S, Farrell CM, Loveland JE, Ruef BJ et al (2009) The consensus coding sequence (CCDS) project: identifying a common protein-coding gene set for the human and mouse genomes. Genome Res 19:1316–1323. doi:10.1101/gr.080531.108
Rambaut A, Drummond AJ (2009) Tracer, MCMC Trace Analysis Tool, v1.5.0. http://beast.bio.ed.ac.uk/Tracer. Acessed in November 2012
Riggio M, Trinchella F, Filosa S, Parisi E, Scudiero R (2003) Accumulation of zinc, copper, and metallothionein mRNA in lizard ovary proceeds without a concomitant increase in metallothionein content. Mol Reprod Dev 66:374–382. doi:10.1002/mrd.10365
Romero-Isart N, Cols N, Termansen MK, Gelpí JL, González-Duarte R, Atrian S, Capdevila M, González-Duarte P (1999) Replacement of terminal cysteine with histidine in the metallothionein alpha and beta domains maintains its binding capacity. Eur J Biochem 259:519–527
Ronquist F, Huelsenbeck JP (2003) MrBayes 3: Bayesian phylogenetic inference under mixed models. Bioinformatics 19:1572–1574. doi:10.1093/bioinformatics/btg180
Saint-Jacques E, April MJ, Séguin C (1995) Structure and metal-regulated expression of the gene encoding Xenopus laevis metallothionein-A. Gene 160:201–206
Schmidt CJ, Hamer DH (1986) Cell specificity and an effect of ras on human metallothionein gene expression. Proc Natl Acad Sci USA 83:3346–3350
Shaw JR, Coulbourne JK, Davey JC, Glaholt SP, Hampton TH, Chen CY, Folt CL, Hamilton JW (2007) Gene response profiles for Daphnia pulex exposed to the environmental stressor cadmium reveals novel crustacean metallothioneins. BMC Genomics 8:477. doi:10.1186/1471-2164-8-477
Tamura K, Peterson D, Peterson N, Stecher G, Nei M, Kumar S (2011) MEGA5: molecular evolutionary genetics analysis using maximum likelihood, evolutionary distance, and maximum parsimony methods. Mol Biol Evol 28:2731–2739. doi:10.1093/molbev/msr121
Tío L, Villarreal L, Atrian S, Capdevila M (2004) Functional differentiation in the mammalian metallothionein gene family: metal binding features of mouse MT4 and comparison with its paralog MT1. J Biol Chem 279:24403–24413. doi:10.1074/jbc.M401346200
Tree of Life Web Project (2012) http://tolweb.org/tree/. Accessed 9 Oct 2012
Trinchella F, Riggio M, Filosa S, Volpe MG, Parisi E, Scudiero R (2006) Cadmium distribution and metallothionein expression in lizard tissues following acute and chronic cadmium intoxication. Comp Biochem Physiol C 144:272–278. doi:10.1016/j.cbpc.2006.09.004
Trinchella F, Riggio M, Filosa S, Parisi E, Scudiero R (2008) Molecular cloning and sequencing of metallothionein in squamates: new insights into the evolution of the metallothionein genes in vertebrates. Gene 423:48–56. doi:10.1016/j.gene.2008.06.027
Trinchella F, Esposito MG, Scudiero R (2012) Metallothionein primary structure in amphibians: insights from comparative evolutionary analysis in vertebrates. C R Biol 335:480–487. doi:10.1016/j.crvi.2012.05.003
Uniprot protein database (2013) www.uniprot.org/uniprot. Accessed 22 April 2013
Valls M, Bofill R, Gonzalez-Duarte R, Gonzalez-Duarte P, Capdevila M, Atrian S (2001) A new insight into metallothionein (MT) classification and evolution. The in vivo and in vitro metal binding features of Homarus americanus recombinant MT. J Biol Chem 276:32835–32843. doi:10.1074/jbc.M102151200
Vašák M, Armitage I (1986) Nomenclature and possible evolutionary pathways of metallothionein and related proteins. Environ Health Perspect 65:215–216
Vašák M, Meloni G (2011) Chemistry and biology of mammalian metallothioneins. J Biol Inorg Chem 16:1067–1078. doi:10.1007/s00775-011-0799-2
Vernot B, Stolzer M, Goldman A, Durand D (2008) Reconciliation with non-binary species trees. J Comput Biol 15:981–1006. doi:10.1089/cmb 2008.0092
Villarreal L, Tío L, Capdevila M, Atrian S (2006) Comparative metal binding and genomic analysis of the avian (chicken) and mammalian metallothionein. FEBS J 273:523–535. doi:10.1111/j.1742-4658.2005.05086.x
Wang Y, Gu X (2001) Functional divergence in the caspase gene family and altered functional constraints: statistical analysis and prediction. Genetics 158:1311–1320
Xia X (2013) DAMBE5: a comprehensive software package for data analysis in molecular biology and evolution. Mol Biol Evol 1–9. doi:10.1093/molbev/mst064
Xia X, Xie Z, Salemi M, Chen L, Wang Y (2003) An index of substitution saturation and its application. Mol Phylogenetic Evol 26:1–7. doi:10.1016/S1055-7903(02)00326-3
Yanai I, Camacho CJ, DeLisi C (2000) Predictions of gene family distributions in microbial genomes: evolution by gene duplication and modification. Phys Rev Lett 85:2641–2644. doi:10.1103/PhysRevLett.85.2641
Yang Z (2007) PAML 4: phylogenetic analysis by maximum likelihood. Mol Biol Evol 24:1586–1591. doi:10.1093/molbev/msm088
Zhang J (2003) Evolution by gene duplication: an update. Trends Ecol Evol 18:292–298. doi:10.1016/S0169-5347(03)00033-8
Zhang J, Rosenberg HF, Nei M (1998) Positive Darwinian selection after gene duplication in primate ribonuclease genes. Proc Natl Acad Sci USA 95:3708–3713
Acknowledgments
We are thankful to M Fonseca, N. Galtier, JM Lourenço, B Nabholz, S Rocha, D Salvi, and Z Yang for feedback on this work. We are grateful to J-P Doyon for his help with the reconciliation analysis and his comments on this part. We are thankful to an anonymous reviewer for comments on an early version of this manuscript. YC was partially financially supported by a FCT (Fundação para Ciência e Tecnologia, Portugal) postdoctoral fellowship SFRH/BDP/73515/2010.
Disclaimer
This study was not sponsored by the U.S. EPA, and the views expressed by the authors in this publication do not necessarily represent the views of the U.S. EPA or the United States.
Author information
Authors and Affiliations
Corresponding author
Additional information
Scott Glaberman—See Disclaimer.
Electronic supplementary material
Below is the link to the electronic supplementary material.
239_2014_9612_MOESM1_ESM.xls
Online Resource 1 Vertebrate metallothionein CDS dataset used in this work (see Materials and Methods for further details). “Annotation” reflects names according to the database used to retrieve this sequence. “Sequence Code” refers to names used for this work. “Length (bp-aa)” refers to length of the full exon when known (CDS+UTR or CDS) in number of base pairs (bp) and the number of amino acids; “Gene Type – Ensembl” with the classification “known” if there is a sequence match to the CDS or protein for the same species, “novel” if there is no match and “known by projection” classification if the transcript is a match for another species. “RefSeq Status – NCBI” as defined according to www.ncbi.nlm.nih.gov/RefSeq/key.html#status; “Location” indicates the interval of basepairs where the CDS is located in the chromosome; “Direction” means the direction of expression of the CDS in the double stranded DNA chromosome. Acession numbers of the sequences are indicated as full gene in Ensembl and NCBI (Gene Acess No and NCBI annotation) and as CDS in Ensembl (Transcript Acess No.). (XLS 73 kb)
239_2014_9612_MOESM2_ESM.pdf
Online Resource 2 List of sequences removed, edited or replaced after checking them on the Ensembl and NCBI genomic databases. (PDF 148 kb)
239_2014_9612_MOESM3_ESM.pdf
Online Resource 3 Bootstrap and posterior probability support values for all phylogenetic analyses represented on the unrooted Bayesian consensus tree (50% majority-rule, one model of evolution) topology obtained with nucleotide data. Numbers on the tree refer to nodes. Bootstrap for ML (in % and only when above 60%) and Posterior Probability (pp only for values above 0.70) values are given for each node (indicated here by the numbers in bold) in the following order: ML nucleotide/ML amino acid/Bayesian nucleotide no partition/Bayesian nucleotide partition/Bayesian amino acid. Values replaced by “-” when below 60% bootstrap or 0.70 pp. Values not shown when clade is not recovered by a specific analysis are indicated with “#”. 1. 96/81/1/1/0.97; 2. 100/65/1/1/1; 3. -/#/-/0.75/#; 4. 75/-/0.88/-/#; 5. -/-/-/#/0.71; 6. 89/-/0.99/1/-; 7. -/-/0.97/0.97/1; 8. 68/74/0.98/0.96/1; 9. 71/-/0.88/0.99/#; 10. -/#/0.73/0.86/#; 11. #/76/-/0.71/#; 12. -/-/0.91/0.99/#; 13. 100/75/0.98/1/0.95; 14. #/#/1/1/#; 15. #/#/0.74/-/#; 16. 87/89/1/1/0.97; 17. -/-/0.97/0.99/0.75; 18. -/-/0.74/0.82/1; 19. 100/98/1/1/0.97; 20. 100/98/1/1/1; 21. 100/98/1/1/1; 22. #/#/-/0.91/#; 23. 100/97/1/1/1; 24. 95/-/1/1/99; 25. #/#/0.75/0.72/#; 26. 95/99/1/1/1; 27. 99/-/0.99/0.96/#; 28. 78/#/0.90/0.85/#; 29. 100/94/1/1/1; 30. -/-/-/0.95/0.96; 31. 78/-/0.79/1/-; 32. -/-/-/-/#; 33. #/#/0.85/#/#; 34. 83/79/0.94/1/1; 35. #/#/0.85/0.96/#; 36. 74/#/0.94/-/#; 37. 76/#/0.94/0.79/#; 38. #/#/-/#/#; 39. 98/96/1/1/1; 40. 99/94/1/1/1; 41. 98/92/0.89/0.99/0.99; 42. 79/-/1/1/0.96; 43. 91/#/1/#/#; 44. -/#/0.66/#/#; 45. 98/92/1/1/0.85; 46. 99/100/1/1/1; 47. 99/79/1/1/0.92; 48. 39/#/-/-/#; 49. 62/#/0.85/0.71/0.99; 50. -/-/-/-/#; 51. 81/84/0.98/0.96/1; 52. 87/84/0.98/1/1; 53. 93/99/1/1/1; 54. 65/-/1/#/#; 55. -/-/0.99/0.88/#; 56. -/#/-/#/#. (PDF 146 kb)
239_2014_9612_MOESM4_ESM.pdf
Online Resource 4 Rooted gene trees resulting from the optimal reconciliation. Gene duplication is indicated with (D), while gene loss is indicated by a dashed line. a) and b) indicate the reconciliation results obtained using the Baysian amino acid and nucletotide gene trees, respectively, as input. (PDF 1895 kb)
239_2014_9612_MOESM5_ESM.pdf
Online Resource 5 Functional divergence alignments (Type I divergence). Vertical bar represents amino acid sites indicated as functionally divergent among the indicated clades for a cut-off value = 0.9. (PDF 375 kb)
Rights and permissions
About this article
Cite this article
Serén, N., Glaberman, S., Carretero, M.A. et al. Molecular Evolution and Functional Divergence of the Metallothionein Gene Family in Vertebrates. J Mol Evol 78, 217–233 (2014). https://doi.org/10.1007/s00239-014-9612-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00239-014-9612-5