ABSTRACT
The present study was carried out in four genetic groups of cattle, viz. Kangayam, Pulikulam, crossbred Jersey and crossbred Holstein Friesian, to compare the karyomorphological pattern between Bos indicus and Bos taurus x indicus bull calves. Metaphase chromosomal spreads obtained by short term lymphocyte culture technique revealed chromosomal complement (2n) of 60, with 29 pairs of autosomes and one pair of sex chromosomes in four groups. All the autosomes were acrocentric, X-chromosome was sub-metacentric and Y-chromosome was acrocentric in Bos indicus and metacentric in crossbred bulls. There was no significant difference in relative length, arm ratio, centromeric index and morphological index of autosomes and X-chromosome between indicine and taurine groups; but Y-chromosome differed significantly (P˂0.01) in relative length between Bos indicus and Bos taurus x indicus crosses. Y-chromosome polymorphism could help in the determination of breed origin and male lines used in the breeding programmes in order to prevent the possible interferences in the process of reproduction
ABSTRACT
Objective To explore the effect of chromosomal polymorphic variations on the outcome of in vitro fertilization/intracytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET) treatment for infertile couples. Methods In this retrospective study, 1 108 infertile couples, who received their first IVF/ICSI-ET treatment cycles in Reproductive Medicine Center of Changhai Hospital of Second Military Medical University from Mar. 2015 to Jun. 2016, were included and divided into two groups:normal chromosomal group (the infertile couples with normal chromosome) and chromosomal polymorphic group (with chromosomal polymorphic variations). The embryo implantation rate, clinical pregnancy rate (CPR), early abortion rate and live birth rate (LBR) after IVF/ICSI-ET treatment were compared and analyzed. Results A total of 1 108 infertile couples received IVF/ICSI-ET treatment were enrolled, with 69 in the chromosomal polymorphic group, and 1 039 in the normal chromosomal group. There were no significant differences between the two groups in embryo implantation rate (34.91% vs 34.62%, P>0.05), CPR (49.09% vs 50.72%, P>0.05), early abortion rate (11.37% vs 8.57%, P>0.05) or LBR (41.67% vs 43.47%, P>0.05). Conclusion Chromosomal polymorphisms appear to have no effect on the outcome of IVF/ICSI-ET treatment for infertile couples.
ABSTRACT
This study aimed to define the karyotype of the recently described Iberian endemic Iberochondrostoma almacai, to revisit the previously documented chromosome polymorphisms of its sister species I. lusitanicum using C-, Ag-/CMA3 and RE-banding, and to compare the two species genome sizes. A 2n = 50 karyotype (with the exception of a triploid I. lusitanicum specimen) and a corresponding haploid chromosome formula of 7M:15SM:3A (FN = 94) were found. Multiple NORs were observed in both species (in two submetacentric chromosome pairs, one of them clearly homologous) and a higher intra and interpopulational variability was evidenced in I. lusitanicum. Flow cytometry measurements of nuclear DNA content showed some significant differences in genome size both between and within species: the genome of I. almacai was smaller than that of I. lusitanicum (mean values 2.61 and 2.93 pg, respectively), which presented a clear interpopulational variability (mean values ranging from 2.72 to 3.00 pg). These data allowed the distinction of both taxa and confirmed the existence of two well differentiated groups within I. lusitanicum: one that includes the populations from the right bank of the Tejo and Samarra drainages, and another that reunites the southern populations. The peculiar differences between the two species, presently listed as "Critically Endangered", reinforced the importance of this study for future conservation plans.
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Cytogenetic analyses performed in populations of the Neotropical freshwater fish Leporinus elongatus of the Upper Paraná River basin showed a chromosome polymorphism involving heterochromatic segments of the nucleolar organizing pair in this species. The NOR-bearing chromosome pair was characterized by two phenotypes identified by the absence (CÕ) or presence (C²) of a heterochromatic segment located in an interstitial position of the long arm in this pair. The meiotic segregation of these variations results in three distinct cytotypes, CÕCÕ, CÕC² and C²C². Both populations were in Hardy-Weinberg equilibrium. Sex-related cytotype divergence was identified and multivariate analyses revealed that the C²C² individuals presented morphometric differentiation relative to body height in relation to the other cytotypes. A chromosome differentiation and a cytotype proportion difference observed between both populations suggest the occurrence of population subdivision within this species along the Upper Paraná River basin. These findings might contribute to the knowledge of the population biology of this fish and for its conservation.
Subject(s)
Animals , Cytogenetic Analysis , Genetics, Population , Fishes/genetics , Genetic Variation , Nucleolus Organizer Region , Polymorphism, GeneticABSTRACT
The Brazilian dwarf brocket deer (Mazama nana) is the smallest deer species in Brazil and is considered threatened due to the reduction and alteration of its habitat, the Atlantic Rainforest. Moreover, previous work suggested the presence of intraspecific chromosome polymorphisms which may contribute to further population instability because of the reduced fertility arising from the deleterious effects of chromosome rearrangements during meiosis. We used G- and C-banding, and nucleolus organizer regions localization by silver-nitrate staining (Ag-NOR) to investigate the causes of this variation. Mazama nana exhibited eight different karyotypes (2n = 36 through 39 and FN = 58) resulting from centric fusions and from inter and intraindividual variation in the number of B chromosomes (one to six). Most of the animals were heterozygous for a single fusion, suggesting one or several of the following: a) genetic instability in a species that has not reached its optimal karyotypic evolutionary state yet; b) negative selective pressure acting on accumulated rearrangements; and c) probable positive selection pressure for heterozygous individuals which maintains the polymorphism in the population (in contrast with the negative selection for many rearrangements within a single individual).
Subject(s)
Animals , Chromosome Banding , Deer/genetics , Polymorphism, Genetic , Brazil , Cytogenetic Analysis , Karyotyping , Nucleolus Organizer RegionABSTRACT
Euchroma gigantea was karyotypically studied using conventional staining, C-banding, silver nitrate staining and ribosomal fluorescent in situ hybridization (rDNA FISH). Broad wide autosomal polymorphism and a complex sex determination system were found in this beetle. Karyotype complements ranging from 2n = 32, X1X2X3Y1Y2Y3 to 2n = 36,X1X2X3Y1Y2Y3 were detected in the sample analyzed. Punctiform supernumerary chromosomes were present in the different karyotypes. The karyotypic evolution of Brazilian E. gigantea may have taken two directions, reduction in the diploid number of 2n = 36 to 24 through centric fusions or 2n = 24 to 36 due to chromosomal fissions. In addition, pericentric inversions were also involved. The complex multiple sex mechanism of this species seems to be old and well established since it is found in specimens from different populations. Small pericentromeric blocks of constitutive heterochromatin were located on the autosomes and terminal blocks were also found on some small pairs. The sex chromosomes showed larger constitutive heterochromatin blocks. Silver nitrate staining during prophase I of meiosis showed labeling of the sex chromosome chain. However, the rDNA sites could only be precisely determined by FISH, which permitted the identification of these ribosomal sites on chromosomes X1 and X2 of this species.