Manuel Alejandro Merlo

• PhD
• Researcher at Universidad de Cádiz

Pleuronectiformes are flatfishes with high commercial value and a prominent example of successful marine adaptation through chromosomal evolution. Hence, the aim of this study was to analyze the 14 relative abundance of repetitive elements (satellite DNA and transposable elements (TE)) in the 15 genome of 10 fish species (8 flatfish) delving into t...

Simple Summary The Senegalese sole (Solea senegalensis, Kaup 1858), a marine flatfish species, is of commercial interest for both fisheries and aquaculture. In aquaculture, currently there are several production bottlenecks, mainly in larvae culture and rearing. The hox genes participate in cell differentiation and structuring of the anterior–poste...

The Pleuronectiformes order, which includes several commercially-important species, has undergone extensive chromosome evolution. One of these species is Solea senegalensis, a flatfish with 2n = 42 chromosomes. In this study, a cytogenomics approach and integration with previous maps was applied to characterize the karyotype of the species. Synteny...

Cytogenomics, the integration of cytogenetic and genomic data, has been used here to reconstruct the evolution of chromosomes 2 and 4 of Solea senegalensis. S. senegalensis is a flat fish with a karyotype comprising 2n = 42 chromosomes: 6 metacentric + 4 submetacentric + 8 subtelocentric + 24 telocentric. The Fluorescence in situ Hybridization with...

Solea senegalensis aquaculture production has experienced a great increase in the last decade and, consequently, the genome knowledge of the species is gaining attention. In this sense, obtaining a high-density genome mapping of the species could offer clues to the aquaculture improvement in those aspects not resolved so far. In the present article...

Knowing the factors responsible for sex determination in a species has significant theoretical and practical implications; the dmrt1 gene (Doublesex and Mab-3 (DM)-related Transcription factor 1) plays this role in diverse animal species. Solea senegalensis is a commercially important flat fish in which females grow 30% faster than males. It has 2n...

The flatfish, Solea senegalensis has considerable scientific interest and commercial value. The metamorphosis in this species occurs between 12 and 19 days after hatching and it takes about 1 week to complete. Eleven Bacterial Artificial Chromosomes (BAC) clones containing the various candidate genes involved in the process of metamorphosis: thyrox...

Triportheus (Characiformes, Triportheidae) is a freshwater fish genus with 18 valid species. These fishes are widely distributed in the major river drainages of South America, having commercial importance in the fishing market, mainly in the Amazon basin. This genus has diverged recently in a complex process of speciation carried out in different r...

Solea senegalensis is a flatfish belonging to the Soleidae family within the Pleuronectiformes order. It has a karyotype of 2n = 42 (FN = 60; 6M + 4 SM + 8 St + 24 T) and a XX/XY system. The first pair of metacentric chromosomes has been proposed as a proto sex-chromosome originated by a Robertsonian fusion between acrocentric chromosomes. In order...

Global aquaculture production continues to increase rapidly. One of the most important species of marine fish currently cultivated in Southern Europe is Solea senegalensis, reaching more than 300 Tn in 2017. In the present work, 14 Bacterial Artificial Chromosome (BAC) clones containing candidate genes involved in the immune system (b2m, il10, tlr3...

Background The re-sequencing of C. angulata has revealed many polymorphisms in candidate genes related to adaptation to abiotic stress that are not present in C. gigas; these genes, therefore, are probably related to the ability of this oyster to retain high concentrations of toxic heavy metals. There is, in addition, an unresolved controversy as t...

Background Solea senegalensis (Kaup, 1858) is a commercially important flatfish species, belonging to the Pleuronectiformes order. The taxonomy of this group has long been controversial, and the karyotype of the order presents a high degree of variability in diploid number, derived from chromosomal rearrangements such as Robertsonian fusions. Previ...

The 5S rDNA array is composed of multiple copies of a conserved transcriptional unit and a variable non-transcribed spacer (NTS). The NTS may include other multigene families, such as small nuclear RNAs (snRNAs) and transposable elements (TEs). Here, we integrated genetic and cytogenetic analyses to better understand the evolutionary patterns of 5S...

The evolution of genes related to sex and reproduction in fish shows high plasticity and, to date, the sex determination system has only been identified in a few species. Solea senegalensis has 42 chromosomes and an XX/XY chromosome system for sex determination, while related species show the ZZ/ZW system. Next-generation sequencing (NGS), multi-co...

Multigene families correspond to a group of genes tandemly repeated, showing enormous diversity in both number of units and genomic organization. In fishes, unlike rDNAs that have been well explored in cytogenetic studies, U2 small nuclear RNA (snRNA) genes are poorly investigated concerning their chromosomal localization. All Triportheus species (...

The Senegalese sole (Solea senegalensis) is commercially very important, and is a priority species for aquaculture product diversification. The main histone cluster was found in two BAC clones. However, two replacement histones (H1.0 and H3.3) were found in another BAC clone. Different types of canonical H2A and H2B have been found in one species f...

BACKGROUND: Senegalese sole (Solea senegalensis) and common sole (S. solea) are two economically and evolutionary important flatfish species both in fisheries and aquaculture. Although some genomic resources and tools were recently described in these species, further sequencing efforts are required to establish a complete transcriptome, and to ide...

Here we describe the whole genome re-sequencing of the Portuguese oyster C. angulata, an edible cupped oyster of major commercial importance with an important role as biosensor of coastal water pollution. We sequenced the genome of the C. angulata to 29.3-fold coverage using ABI SOLID system. Comparisons of the sequences with the reference assembly...

Doublesex and mab-3 related transcription factor 1 (Dmrt1) gene is a widely conserved gene involved in sex determination and differentiation across phyla. To gain insights on Dmrt1 implication for fish gonad cell differentiation and gametogenesis development, its mRNA was isolated from testis and ovary from the Lusitanian toadfish (Halobatrachus di...

This article presents the first physical mapping carried out in the Senegalese sole (Solea senegalensis), an important marine fish species of Southern Europe. Eight probes were designated to pick up genes of interest in aquaculture (candidate genes) from a bacterial artificial chromosome (BAC) library using a method of rapid screening based on a 4-...

The 5S ribosomal DNA (rDNA) consists of one transcriptional unit of about 120 base pairs, which is separated from the next unit by a non-transcribed spacer (NTS). The coding sequence and the NTS together form a repeat unit which can be found in hundreds to thousands of copies tandemly repeated in the genomes. The NTS regions seem to be subject to r...

The meagre (Argyrosomus regius) is a commercially important species for fisheries, and aquaculture production has been increasing in recent years. However, this growing importance has not been matched by increased genetic knowledge of the species. For this reason, an initial approach has been made to understanding the genetics of the meagre, using...

There has been considerable discussion in recent years on the evolution of the tandemly repeated multigene families, since some organisms show a concerted model whereas others show a birth-and-death model. This controversial subject extends to several species of fish. In this study, three species of the Sparidae family (Pagrus pagrus, P. auriga and...

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 thi...

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Molecular and cytogenetic markers are of great use for to fish characterization, identification, phylogenetics and evolution. Multigene families have proven to be good markers for a better understanding of the variability, organization and evolution of fish species. Three different tandemly-repeated gene families (45S rDNA, 5S rDNA and U2 snDNA) ha...

Halobatrachus didactylus (Schneider, 1801) has a chromosome number of 2n = 46 (8 metacentrics, 12 submetacentrics and 26 acrocentrics). Specimens studied were collected from waters of the Bay of Cadiz. Chromosome preparations were made from the cephalic portion of the kidney. The telomeric probe hybridized on the terminal position of all toadfish c...

By analyzing three multigene families, two closely related and commercially important species, Dicentrarchus labrax and Dicentrarchus punctatus, were characterized by cytogenetic and molecular methods. The interspecies hybrid Dicentrarchus labrax (♀) × Dicentrarchus punctatus (♂) was also analyzed. The multigene families studied were the 5S rDNA, 4...

5S ribosomal DNA (rDNA) sequences were analyzed in four species belonging to different genera of the fish family Batrachoididae. Several 5S rDNA variants differing in their non-transcribed spacers (NTSs) were found and were grouped into two main types. Two species showed both types of 5S rDNA, whereas the other two species showed only one type. One...

In the present study dual-colour fluorescence in situ hybridization (FISH) was performed to study the chromosomal distribution of 18S and 5S rDNAs, (GATA)n and 5S rDNA, and U2 snRNA and 18S rDNA in four species of Batrachoididae family: Amphichthys cryptocentrus, Batrachoides manglae, Porichthys plectrodon and Thalassophryne maculosa. The 18S rDNA...