Occurrence of macro B chromosomes in Astyanax scabripinnis paranae (Pisces, Characiformes, Characidae)

Genetica ◽  
1992 ◽  
Vol 87 (2) ◽  
pp. 101-106 ◽  
Author(s):  
E. L. Maistro ◽  
F. Foresti ◽  
C. Oliveira ◽  
L. F. de Almeida Toledo
Keyword(s):  
B Chromosomes ◽  
Astyanax Scabripinnis

New insights on the origin of B chromosomes in Astyanax scabripinnis obtained by chromosome painting and FISH

Genetica ◽  
2011 ◽  
Vol 139 (8) ◽  
pp. 1073-1081 ◽  
Author(s):  
Marcelo Ricardo Vicari ◽  
Helena Flávia de Mello Pistune ◽  
Jonathan Pena Castro ◽  
Mara Cristina de Almeida ◽  
Luiz Antonio Carlos Bertollo ◽  
...  
Keyword(s):  
Chromosome Painting ◽  
B Chromosomes ◽  
Astyanax Scabripinnis

scholarly journals Differential Expression of Genes Related to Sexual Determination Can Modify the Reproductive Cycle of Astyanax scabripinnis (Characiformes: Characidae) in B Chromosome Carrier Individuals

Genes ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 909 ◽  
Author(s):  
Jonathan Pena Castro ◽  
Ricardo Shohei Hattori ◽  
Túlio Teruo Yoshinaga ◽  
Duílio Mazzoni Zerbinato de Andrade Silva ◽  
Francisco J. Ruiz-Ruano ◽  
...  
Keyword(s):  
Differential Expression ◽  
Reproductive Cycle ◽  
Model Organism ◽  
B Chromosome ◽  
B Chromosomes ◽  
Astyanax Scabripinnis ◽  
Expression Of Genes ◽  
Sexual Determination ◽  
The Difference ◽  
Differential Expression Of Genes

The species complex Astyanax scabripinnis is one of the most studied with respect to origin, distribution, and frequency of B chromosomes, and is considered a model organism for evolutionary studies. Research using population inferences about the occurrence and frequency of the B chromosome shows seasonal variation between sexes, which is associated with the presence of this supernumerary element. We hypothesized that the B chromosome could influence the sex ratio of these animals. Based on this assumption, the present work aimed to investigate if differences exist among levels of gene expression with qRT-PCR of the amh (associated with testicular differentiation) and foxl2a (associated with ovarian differentiation) genes between B-carrier and non-B-carrier individuals. The results showed that for the amh gene, the difference in expression between animals with B chromosomes was not accentuated compared to that in animals without this chromosome. Expression of foxl2a in B-carrier females, however, was reduced by 73.56% compared to females that lacked the B chromosome. Males had no difference in expression of the amh and foxl2a genes between carriers and non-carriers of the B chromosome. Results indicate that the presence of B chromosomes is correlated with the differential expression of sex-associated genes. An analysis of these results integrated with data from other studies on the reproductive cycle in the same species reveals that this difference in expression may be expanding the reproductive cycle of the species.

scholarly journals B chromosomes in Astyanax scabripinnis (Pisces, Characidae)

Heredity ◽  
1992 ◽  
Vol 69 (1) ◽  
pp. 50-56 ◽  
Author(s):  
Lara Bellintani Salvador ◽  
Orlando Moreira-Filho
Keyword(s):  
B Chromosomes ◽  
Astyanax Scabripinnis

scholarly journals Genetic variability in a population of Astyanax scabripinnis: recent bottleneck and the possible influence of individuals with B chromosomes

2019 ◽  
Vol 41 ◽  
pp. e47323
Author(s):  
Daniel Meneguello Limeira ◽  
Mateus Henrique Santos ◽  
Rogério Pincela Mateus ◽  
Mara Cristina de Almeida ◽  
Roberto Ferreira Artoni
Keyword(s):  
Genetic Variability ◽  
Microsatellite Markers ◽  
Allelic Diversity ◽  
B Chromosomes ◽  
Isolated Populations ◽  
Population Genetic Analysis ◽  
Genetic Studies ◽  
Astyanax Scabripinnis ◽  
Heterozygosity Excess ◽  
Recent Bottleneck

Access the genetic variability of endangered and isolated populations has become an important conservation tool. Astyanax scabripinnis is a well-known fish model for genetic studies, forming very isolated populations in headwaters. Besides that, this species frequently presents supernumerary chromosomes, which elevates the interest on genetic studies. Genetic diversity of an Astyanax scabripinnis population from the Atlantic Forest (Serra da Mantiqueira region, Brazil) was assessed with microsatellite markers for the first time. Since microsatellite markers are not described for this species, we tested markers described for a related species for transferability to A. scabripinnis. Six polymorphic loci were sufficiently reliable for population genetic analysis. We found that this population passed through a recent bottleneck because of the presence of an excess of heterozygotes, low allelic diversity, heterozygosity excess, and small effective population size. Individuals with and without B chromosomes were previously identified in this population and our study found private alleles in the individuals without B chromosomes. Furthermore, when individuals without B chromosomes were removed from the analysis, the population did not present heterozygosity excess, suggesting that the bottleneck event was driven by individuals with B chromosomes. Our results provide an insight into the value of microsatellite markers as molecular tools and is the first genetic study using molecular data of A. scabripinnis from this area.

scholarly journals Estimated frequency of B-chromosomes and population density of Astyanax scabripinnis paranae in a small stream

1997 ◽  
Vol 20 (3) ◽  
pp. 377-380 ◽  
Author(s):  
Fábio Porto-Foresti ◽  
Claudio Oliveira ◽  
Edson Luis Maistro ◽  
Fausto Foresti
Keyword(s):  
Population Density ◽  
B Chromosome ◽  
B Chromosomes ◽  
Small Stream ◽  
The Third ◽  
Astyanax Scabripinnis ◽  
Significant Difference ◽  
Adaptive Effect

A study was made of the frequency of B-chromosomes and the population density of Astyanax scabripinnis paranae (Pisces, Characidae, Tetragonopterinae) from three stretches of the Cascatinha stream (Botucatu, SP). In the first stretch the population was estimated to be about 212 individuals and among 35 karyotyped specimens, 23 carried one macro B-chromosome; in the second stretch the population was estimated to be about 650 individuals and among 20 specimens karyotyped, two possessed one macro B-chromosome; in the third stretch the population was estimated to be about 107 individuals and among 10 specimens karyotyped, one carried one macro B-chromosome. A significant difference was observed in the frequency of macro B-chromosomes in females (57%) and males (8.7%) (P = 0.0001). These data suggest that the B-chromosome frequency and the populational density are not directly related. The hypothesis of the existence of some adaptive effect conferred by the B-chromosomes to the specimens from the first stretch of the Cascatinha stream is presented and discussed

scholarly journals Chromosomal Instability at Fragile Sites in Blue Foxes, Silver Foxes, and Their Interspecific Hybrids

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1743
Author(s):  
Marta Kuchta-Gładysz ◽  
Ewa Wójcik ◽  
Anna Grzesiakowska ◽  
Katarzyna Rymuza ◽  
Olga Szeleszczuk
Keyword(s):  
Interspecific Hybrids ◽  
Genome Stability ◽  
Diploid Number ◽  
Fragile Sites ◽  
B Chromosomes ◽  
Silver Fox ◽  
Chromosomal Breaks ◽  
Blue Fox ◽  
Chromosomal Fragile Sites ◽  
Karyotypic Variation

A cytogenetic assay based on fragile sites (FS) enables the identification of breaks, chromatid gaps, and deletions. In healthy individuals, the number of these instabilities remains low. Genome stability in these species is affected by Robertsonian translocations in the karyotype of the blue fox and by B chromosomes in the silver fox. The aims of the study were to characterise the karyotype of blue foxes, silver foxes, and their hybrids and to identify chromosomal fragile sites used to evaluate genome stability. The diploid number of A chromosomes in blue foxes ranged from 48 to 50, while the number of B chromosomes in silver foxes varied from one to four, with a constant number of A chromosomes (2n = 34). In interspecific hybrids, both types of karyotypic variation were identified, with the diploid number of A chromosomes ranging from 40 to 44 and the number of B chromosomes varying from 0 to 3. The mean frequency of FS in foxes was 4.06 ± 0.19: 4.61 ± 0.37 in blue foxes, 3.46 ± 0.28 in silver foxes, and 4.12 ± 0.22 in hybrids. A relationship was identified between an increased number of A chromosomes in the karyotype of the hybrids and the frequency of chromosomal breaks. The FS assay was used as a biomarker for the evaluation of genomic stability in the animals in the study.

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