PMID- 23039906 OWN - NLM STAT- MEDLINE DCOM- 20130603 LR - 20211021 IS - 1471-2148 (Electronic) IS - 1471-2148 (Linking) VI - 12 DP - 2012 Oct 7 TI - Evidence for 5S rDNA horizontal transfer in the toadfish Halobatrachus didactylus (Schneider, 1801) based on the analysis of three multigene families. PG - 201 LID - 10.1186/1471-2148-12-201 [doi] AB - BACKGROUND: The Batrachoididae family is a group of marine teleosts that includes several species with more complicated physiological characteristics, such as their excretory, reproductive, cardiovascular and respiratory systems. Previous studies of the 5S rDNA gene family carried out in four species from the Western Atlantic showed two types of this gene in two species but only one in the other two, under processes of concerted evolution and birth-and-death evolution with purifying selection. Here we present results of the 5S rDNA and another two gene families in Halobatrachus didactylus, an Eastern Atlantic species, and draw evolutionary inferences regarding the gene families. In addition we have also mapped the genes on the chromosomes by two-colour fluorescence in situ hybridization (FISH). RESULTS: Two types of 5S rDNA were observed, named type alpha and type beta. Molecular analysis of the 5S rDNA indicates that H. didactylus does not share the non-transcribed spacer (NTS) sequences with four other species of the family; therefore, it must have evolved in isolation. Amplification with the type beta specific primers amplified a specific band in 9 specimens of H. didactylus and two of Sparus aurata. Both types showed regulatory regions and a secondary structure which mark them as functional genes. However, the U2 snRNA gene and the ITS-1 sequence showed one electrophoretic band and with one type of sequence. The U2 snRNA sequence was the most variable of the three multigene families studied. Results from two-colour FISH showed no co-localization of the gene coding from three multigene families and provided the first map of the chromosomes of the species. CONCLUSIONS: A highly significant finding was observed in the analysis of the 5S rDNA, since two such distant species as H. didactylus and Sparus aurata share a 5S rDNA type. This 5S rDNA type has been detected in other species belonging to the Batrachoidiformes and Perciformes orders, but not in the Pleuronectiformes and Clupeiformes orders. Two hypotheses have been outlined: one is the possible vertical permanence of the shared type in some fish lineages, and the other is the possibility of a horizontal transference event between ancient species of the Perciformes and Batrachoidiformes orders. This finding opens a new perspective in fish evolution and in the knowledge of the dynamism of the 5S rDNA. Cytogenetic analysis allowed some evolutionary trends to be roughed out, such as the progressive change in the U2 snDNA and the organization of (GATA)n repeats, from dispersed to localized in one locus. The accumulation of (GATA)n repeats in one chromosome pair could be implicated in the evolution of a pair of proto-sex chromosomes. This possibility could situate H. didactylus as the most highly evolved of the Batrachoididae family in terms of sex chromosome biology. FAU - Merlo, Manuel A AU - Merlo MA AD - Laboratorio Genetica, Facultad de Ciencias del Mar y Ambientales, CACYTMAR, Universidad de Cadiz, Puerto Real (Cadiz), 11510, Spain. FAU - Cross, Ismael AU - Cross I FAU - Palazon, Jose L AU - Palazon JL FAU - Ubeda-Manzanaro, Maria AU - Ubeda-Manzanaro M FAU - Sarasquete, Carmen AU - Sarasquete C FAU - Rebordinos, Laureana AU - Rebordinos L LA - eng SI - GENBANK/JN406320 SI - GENBANK/JN406321 SI - GENBANK/JN406322 SI - GENBANK/JN406323 SI - GENBANK/JN406324 SI - GENBANK/JN406325 SI - GENBANK/JN406326 SI - GENBANK/JN406327 SI - GENBANK/JN406328 SI - GENBANK/JN406329 SI - GENBANK/JN406330 SI - GENBANK/JN406331 SI - GENBANK/JN406332 SI - GENBANK/JN406333 SI - GENBANK/JN406334 SI - GENBANK/JN406335 SI - GENBANK/JN406336 SI - GENBANK/JN406337 SI - GENBANK/JN406338 SI - GENBANK/JN406339 SI - GENBANK/JN406340 SI - GENBANK/JN406341 SI - GENBANK/JN406342 SI - GENBANK/JN406343 SI - GENBANK/JN406344 SI - GENBANK/JN406345 SI - GENBANK/JN406346 SI - GENBANK/JN406347 SI - GENBANK/JN406348 SI - GENBANK/JN406349 SI - GENBANK/JN406350 SI - GENBANK/JN406351 SI - GENBANK/JN406352 SI - GENBANK/JN406353 SI - GENBANK/JN406354 SI - GENBANK/JN406355 SI - GENBANK/JN406356 SI - GENBANK/JN406357 SI - GENBANK/JN406358 SI - GENBANK/JN406359 SI - GENBANK/JN406360 SI - GENBANK/JN406361 SI - GENBANK/JN406362 SI - GENBANK/JN406363 SI - GENBANK/JN406364 SI - GENBANK/JN406365 SI - GENBANK/JN406366 SI - GENBANK/JN406367 SI - GENBANK/JN406368 SI - GENBANK/JN406369 SI - GENBANK/JN406370 PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20121007 PL - England TA - BMC Evol Biol JT - BMC evolutionary biology JID - 100966975 RN - 0 (DNA, Ribosomal) RN - 0 (DNA, Ribosomal Spacer) RN - 0 (RNA, Ribosomal, 5S) RN - 0 (RNA, Small Nuclear) RN - 0 (U2 small nuclear RNA) SB - IM MH - Animals MH - Base Sequence MH - Batrachoidiformes/*genetics MH - DNA, Ribosomal/chemistry/classification/*genetics MH - DNA, Ribosomal Spacer/chemistry/classification/genetics MH - Electrophoresis, Agar Gel MH - *Gene Transfer, Horizontal MH - In Situ Hybridization, Fluorescence MH - Molecular Sequence Data MH - *Multigene Family MH - Perciformes/genetics MH - Phylogeny MH - RNA, Ribosomal, 5S/*genetics MH - RNA, Small Nuclear/genetics MH - Sequence Analysis, DNA MH - Sequence Homology, Nucleic Acid PMC - PMC3544641 EDAT- 2012/10/09 06:00 MHDA- 2013/06/05 06:00 PMCR- 2012/10/07 CRDT- 2012/10/09 06:00 PHST- 2012/03/29 00:00 [received] PHST- 2012/10/03 00:00 [accepted] PHST- 2012/10/09 06:00 [entrez] PHST- 2012/10/09 06:00 [pubmed] PHST- 2013/06/05 06:00 [medline] PHST- 2012/10/07 00:00 [pmc-release] AID - 1471-2148-12-201 [pii] AID - 10.1186/1471-2148-12-201 [doi] PST - epublish SO - BMC Evol Biol. 2012 Oct 7;12:201. doi: 10.1186/1471-2148-12-201.