Comparative Chromosome Painting in Genets (Carnivora, Viverridae, Genetta), the Only Known Feliforms with a Highly Rearranged Karyotype

Mammalian carnivores have been extensively studied by cross-species chromosome painting, which indicated a high degree of karyotypic conservatism in the cat-like suborder Feliformia relative to the ancestral carnivore karyotype (ACK). The first exception to this high degree of karyotypic conservation in feliforms was recently confirmed in genets, mesocarnivores belonging to the basal family Viverridae. Here, we present a comparative analysis of the chromosome rearrangements among 2 subspecies of the small-spotted genet Genetta genetta (the Iberian nominate and the Arabian grantii) and the panther genet G. maculata, the 2 most common and widespread genets, using whole-chromosome paints from the domestic cat (Felis catus). The chromosome homology maps and the presence of numerous interstitial telomeric sites in both genet species strengthen the hypothesis that a highly rearranged karyotype compared to the ACK may occur throughout Genetta. The karyotype of G. maculata appears to have undergone more rearrangements than that of G. genetta, which is an older lineage. Notably, we identified a tandem fusion distinguishing G. g. genetta and G. g.grantii. As G. g. grantii is morphologically and genetically distinctive, and tandem fusions have been associated with substantial postzygotic isolation in mammals, this cytogenetic finding flags the subspecies for future taxonomic investigations.

Nonhomologous Chromosome Pairing in Aegilops-Secale Hybrids

Intergeneric hybrids and amphidiploid hybrids from crosses of Aegilopstauschii and Secale cereale were produced using young embryo rescue. The hybrids showed complete sets of both parental chromosomes. The dihaploid plants showed an average meiotic pairing configuration of 10.84 I + 1.57 II + 0.01 III. Genomic in situ staining revealed 3 types of bivalent associations, i.e. D-D, R-R and D-R at frequencies of 8.6, 8.2 and 83.3%, respectively. Trivalents consisted of D-R-D or R-D-R associations. These results suggested that both intra- and intergenomic chromosome homology were contributed to chromosome pairing. Derived amphidiploids with 2n = 28 paired at metaphase I of meiosis as 4.51 I + 11.70 II + 0.03 III. Chromosome pairing of amphidiploids appeared more or less regular, i.e. bivalent-like with some trivalent configurations.