Conserved number of U2 snDNA sites in Piabina argentea, Piabarchus stramineus and two Bryconamericus species (Characidae, Stevardiinae)

Abstract

The chromosomal location of 5S rRNA and U2 snRNA genes of Piabina argentea, Piabarchus stramineus and two Bryconamericus species from two different Brazilian river basins were investigated, in order to contribute to the understanding of evolutionary characteristics of these repetitive DNAs in the subfamily Stevardiinae. The diploid chromosome number was 2n = 52 for Bryconamericus cf. iheringii, Bryconamericus turiuba, Piabarchus stramineus and Piabina argentea. The 5S rDNA clusters were located on one chromosome pair in P. stramineus and B. cf. iheringii, and on two pairs in B. turiuba and P. argentea. The U2 snDNA clusters were located on the one pair in all species. Two-color FISH experiments showed that the co-localization between 5S rDNA and U2 snDNA in P. stramineus can represent a marker for this species. Thus, the present study demonstrated that the number of U2 snDNA clusters observed for the four species was conserved, but particular characteristics can be found in the genome of each species.A localização cromossômica dos genes de RNAr 5S e RNAsn U2 de Piabina argentea, Piabarchus stramineus e duas espécies de Bryconamericus provenientes de duas bacias hidrográficas foi investigada, com a intenção de contribuir com o entendimento de características evolutivas destes DNAs repetitivos na subfamília Stevardiinae. O número cromossômico diploide foi 2n = 52 para Bryconamericus cf. iheringii, Bryconamericus turiuba, Piabarchus stramineus e Piabina argentea. Os sítios de DNAr 5S foram localizados em um par cromossômico em P. stramineus e B. cf. iheringii, e em dois pares em B. turiuba e P. argentea. Os sítios de DNAsn U2 foram localizados em um par em todas as espécies. Experimentos de FISH com duas sondas mostraram que a co-localização entre os DNAr 5S e DNAsn U2 em P. stramineus pode representar um marcador para esta espécie. Portanto, o presente estudo demonstrou que o número de sítios de DNAsn U2 observado para as quatro espécies foi conservado, porém características particulares podem ser encontradas no genoma de cada espécie.Palavras-chave: DNA repetitivo, DNAr 5S, Cromossomo, Número diploide. Splicing.

Molecular cytogenetic analysis and the establishment of a cell culture in the fish species Hollandichthys multifasciatus (Eigenmann & Norris, 1900) (Characiformes, Characidae)

“…The U snDNA genes (U1, U2, U4, and U6) are conserved in the eukaryotic genome, and are associated with essential mechanisms for the processing of mRNA by associated proteins (Marz et al, 2008). However, few studies are available on the chromosomal organization and dynamics of these genes in fishes (Silva et al, 2015;Santos et al, 2017;Yano et al, 2017;Nirchio et al, 2018;Piscor et al, 2018). The present study provides the first chromosomal mapping of the U genes in H. multifasciatus, although they indicated a similar configuration to that found in other characids (Silva et al, 2015).…”

“…The U1, U4 e U6 snDNA sequences occurred in a single chromosome pair, while U2 snDNA was mapped in two pairs. The presence of two chromosomal pairs with U2 snDNA sequences was described for species of Astyanax (Silva et al, 2015) and Triportheus (Yano et al, 2017) and in other groups a single pair was observed (Piscor et al, 2018;Nirchio et al, 2020).…”

Cytogenetic markers as tools in delimiting species of the highly diverse Neotropical fish Bryconamericus (Characiformes: Characidae)

“…ecai differed from other populations already studied (Santos et al, 2012(Santos et al, , 2017. This indicates a high degree of chromosomal rearrangements, common in other Stevardiinae genera such as Piabina (Fernandes et al, 2010;Pazian et al, 2012;Piscor et al, 2018) and Piabarchus (Fernandes et al, 2010, cited as Bryconamericus), and in other complex groups of Characidae, such as the Serrasalmus (Martins-Santos et al, 1994;Centofante et al, 2002), Cheirodon (Soto et al, 2018) and Astyanax (Yano et al, 2014;Paiz et al, 2015;Nishiyama et al, 2016, among others).…”

Evolutionary insights in Amazonian turtles (Testudines, Podocnemididae): co-location of 5S rDNA and U2 snRNA and wide distribution of Tc1/Mariner

“…Although the U2 snRNA genes show some sequence conservation, in situ mapping reveals that their distribution patterns can be widely diverse among the karyotypes of some groups. For example, the U2 snRNAs can be: i) organized into a single or small number of chromosomal clusters, as reported in fish (Araya-Jaime et al, 2017;Piscor et al, 2018) and some invertebrates (Almeida et al, 2017;Anjos et al, 2018); ii) arranged in multiple clusters, as observed in some fish (Xu et al, 2017); iii) dispersed in small copies throughout the genome, as in fish of the family Batrachoididae (Úbeda-Manzanaro et al, 2010); iv) allocated on supernumerary chromosomes, as noted in the grasshopper, Abracris flavolineata (Bueno et al, 2013); and v) or in sex chromosomes, as described in grasshoppers of the subfamily Melanoplinae (Palacios-Gimenez et al, 2013). This broad heterogeneity of chromosomal location observed for U2 snRNA genes may be related to the evolutionary history of the snRNA U family, whose Biology Open • Accepted manuscript by guest on September 16, 2020 http://bio.biologists.org/ Downloaded from members can behave as mobile elements and exhibit very little conserved synteny (Marz et al, 2008).…”

“…Most of the investigated karyotypes have relatively few (often just one) 5S rDNA loci (Sochorová et al, 2018;Frade et al, 2019). The 5S rDNA has been reported to co-localize with other multigenes, such as histones genes and small nuclear RNAs (snRNAs) of the U family (Novotná et al 2011;Piscor et al, 2018); these associations seem to indicate an old and linked organization of such sequences in the genomes of the relevant species (Cabral-de- Mello et al, 2011).…”