Intraspecific crosses resulting in the first occurrence of eight and nine B chromosomes in Prochilodus lineatus (Characiformes, Prochilodontidae)

Abstract

B chromosomes are supernumerary elements present in about 15% of eukaryotic species and are most frequently heterochromatic, behave parasitically, show a transmission rate higher than standard (A) chromosomes, and can provoke harmful effects on carriers. In the current work, Prochilodus lineatus individuals carrying eight and nine B chromosomes were obtained by induced crossing performed involving breeders with different B chromosome numbers in their cells. The high B chromosome numbers found in the offspring were recorded for the first time in this species. The use of cytogenetic techniques applied in the present study revealed that regardless of the increase in number of B chromosomes in the genome of these individuals, those elements did not presented active genes, and showed their normal heterochromatic characteristic.

Repetitive sequences: the hidden diversity of heterochromatin in prochilodontid fish

“…Cross-FISH using Semaprochilodus insignis and Semaprochilodus taeniurus Cot-1 DNA probes revealed hybridization signals in the subterminal regions of Prochilodus lineatus , in contrast to the heterochromatic pattern revealed by the C-banding technique with heterochromatin blocks being primarily observed in the centromeric region ( Pauls and Bertollo 1990 , Venere et al 1990, Cavallaro et al 2000 , Artoni et al 2006 , Vicari et al 2006 , Voltolin et al 2011 ). These data indicate that the repetitive fraction of centromeric heterochromatin of Prochilodus lineatus is different from the other two species examined ( Semaprochilodus insignis and Semaprochilodus taeniurus ) and that shared repetitive sequences are located on the subtelomeric portions of their chromosomes.…”

“…Large heterochromatic blocks can be observed, however, in the supernumerary chromosomes (i.e., the B chromosomes) of Prochilodus spp. ( Vicari et al 2006 , Voltolin et al 2011 ) and in the W sex chromosome of Semaprochilodus taeniurus ( Feldberg et al 1987 , Terencio et al 2012 a). Fluorescence in situ hybridization using species-specific probes of the repetitive fractions of the genomes partially confirmed the heterochromatic pattern demonstrated with the C-banding technique in both Semaprochilodus insignis and Semaprochilodus taeniurus – and positive signals were detected in the centromeric regions of all of their chromosomes.…”

Transmission Behavior of B Chromosomes in <b><i>Prochilodus lineatus </i></b>(Characiformes, Prochilodontidae)

“…These B chromosomes were easily identified as heterochromatic microchromosomes with a variable frequency of 0-9 elements [Voltolin et al, 2011]. Furthermore, Artoni et al [2006] reported polymorphisms among the supernumerary chromosomes in the population of P. lineatus from the Mogi-Guaçu River, representing 3 morphotypes identified as meta-, submeta-, and acrocentric B chromosomes.…”

B chromosomes in the species Prochilodus argenteus (Characiformes, Prochilodontidae): morphologicalidentity and dispersion

“…A higher frequency of variation is found in Prochilodus lineatus , which includes individuals without B chromosomes as well as others with up to nine supernumerary elements (Voltolin et al 2011). In other carrier species the frequency of occurrence is less wide-ranging, with zero to three in Prochilodus mariae (Oliveira et al 2003) and from zero to two in Prochilodus brevis and Prochilodus nigricans (Pauls and Bertollo 1990, Venere et al 1999).…”