Chromosomal Dynamics in Cercopithecini Studied by Williams-Beuren probe mapping

Abstract

Chromosomal evolution in the tribe Cercopithecini and in related taxa is highly debated. Uncertainty in reconstruction is mainly related to the great genetic variability and polymorphism of the taxa. Recent molecular and karyological efforts individuate a split between genetically conservative, arbitrarily defi ned, "terrestrial" guenons and vervets, and genetically variable and derived "arboreal" guenons. We performed the mapping of WS loci probe (7q11.23) in order to verify the chromosomal dynamics of the genomes of three tree-dwelling species of the tribe: C. neglectus, C. mitis mitis, C. albogularis labiatus. Data from literature for the "ground-dwelling" Chlorocebus aethiops sabaeus has been compared with our results. The distribution of the WS probe showed a high genomic dynamics in the different species, with three different pattern of rearrangements. Starting from the ancestral synteny 7 found in Pongo pygmaeus (PPY), the present mapping demonstrates different location of the hybridizations signals. A parsimonious interpretation lead to the hypothesis that a pericentric inversion transformed the PPY orthologous in C. neglectus. The C. mitis and the strictly related C. a. labiatus demonstrate more complex, and derivative, rearrangements. According to the position of the WS signal, and to banding pattern analysis, C. mitis and C. albogoularis, underwent to the pericentric inversion, followed by a paracentric inversion and a successive interstitial fi ssion that fragmented the synteny. Starting from the PPY like orthologous a single and independent event, a centric fi ssion, that did not affect the WS position, occurred in Ch. aethiops producing a Gorilla gorilla like chromosome. Our results confi rm the hypothesis that chromosomal dynamics in Cercopithecini proceed by fi ssions and inversions and indicate the usefulness of the locus specifi c mapping approach for the identifi cation of intrachromosome rearrangements.

Chromosome Painting in Cercopithecus petaurista (Schreber, 1774) Compared to Other Monkeys of the Cercopithecini Tribe (Catarrhini, Primates)

“…The human probes showed from one to three fragments, with bright signals (Figures 1 and 2). Twelve human paints (4,7,9,10,13,15,16,17,18,19,20,21,22, and X) were hybridized completely with a single C. petaurista chromosome. Nine human paints were found fragmented, either into two (paints 5, 6, 8, 11, 12, and 14) or three segments (paints 1, 2, and 3) (Figures 1 and 2).…”

“…Cytogenetic and molecular approaches have supported clustering the tribe into two groups: primarily terrestrial and more chromosomally conservative monkeys, and arboreal and chromosomally non-conservative guenons. However, the composition of these species groups, and the relationships between the arboreal species are still unclear [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. In order to acquire further information regarding the complex phylogenomics of this tribe, we utilized the painting approach, using the complete set of human probes on C. petaurista .…”

“…Chromosomal analysis [ 5 , 6 , 7 ] and data from different molecular approaches [ 8 , 9 , 10 ] have led researchers to propose subdividing the tribe into two primary clades of terrestrial and strictly arboreal monkeys. However, other morphological and chromosomal evidence does not support a phylogenetically significant separation of the tribe into two subgroups [ 11 , 12 , 13 ]; for this reason, their phylogeny remains the subject of debate [ 14 ].…”