Genetic aspects in hominid evolution

Genomic comparison between apes and humans have made important contributions to our understanding of human evolution. The modern period of karyological comparisons between humans and other primates began about forty years ago and has been marked by a series of technical revolutions. In the 1960s pioneering genetic and chromosomal comparisons of human and great apes suggested, as had Darwin a century before, that our closest relative were the African apes. Early immunological analyses placed human/apes divergence at about five million year ago. Acceptance of man’s late divergence from the African apes was delayed by the scarcity of paleontological evidence coupled with a fallacious Asiatic o…

Phylogenomics of species from four genera of New World monkeys by flow sorting and reciprocal chromosome painting

Abstract Background The taxonomic and phylogenetic relationships of New World monkeys (Platyrrhini) are difficult to distinguish on the basis of morphology and because diagnostic fossils are rare. Recently, molecular data have led to a radical revision of the traditional taxonomy and phylogeny of these primates. Here we examine new hypotheses of platyrrhine evolutionary relationships by reciprocal chromosome painting after chromosome flow sorting of species belonging to four genera of platyrrhines included in the Cebidae family: Callithrix argentata (silvered-marmoset), Cebuella pygmaea (pygmy marmoset), Callimico goeldii (Goeldi's marmoset) and Saimiri sciureus (squirrel monkey). This is t…

Exploring Evolution in Ceboidea (Platyrrhini, Primates) by Williams-Beuren Probe (HSA 7q11.23) Chromosome Mapping

The ancestral platyrrhine karyotype was characterised by a syntenic association of human 5 and a small segment of human 7 orthologues. This large syntenic association has undergone numerous rearrangements in various phylogenetic lines. We used a locus-specific molecular cytogenetic approach to study the chromosomal evolution of the human 7q11.23 orthologous sequences (William-Beuren syndrome, WS) in various Ceboidea (Platyrrhini) species. The fluorescent in situ hybridisation of the WS probe revealed a two-way pattern of chromosomal organisation that suggests various evolutionary scenarios. The first pattern (seen in Callimico and Saimiri ) includes a fairly simple disruption of the 7/5 syn…

Mapping genomic rearrangements in titi monkeys by chromosome flow sorting and multidirectional in-situ hybridization.

We developed chromosome painting probes for Callicebus pallescens from flow-sorted chromosomes and used multidirectional chromosome painting to investigate the genomic rearrangements in C. cupreus and C. pallescens. Multidirectional painting provides information about chromosomal homologies at the subchromosomal level and rearrangement break points, allowing chromosomes to be used as cladistic markers. Chromosome paints of C. pallescens were hybridized to human metaphases and 43 signals were detected. Then, both human and C. pallescens probes were hybridized to the chromosomes of another titi monkey, C. cupreus. The human chromosome paints detected 45 segments in the haploid karyotype of C.…

Multi-directional painting in loriform prosimians

Primate Cytogenetics and Comparative Genomics

This volume is a collection of contributions of a Florentine post congress symposium on "Primate Cytogenetics and Comparative Genomics" held on occasion of the XX International Primatological Congress (Turin in 2004). Comparative Molecular Cytogenetics and Genomics are two rapidly expanding fields. Researchers from Italy, Germany, Spain, United States and Japan meet in Florence to discuss over a two day period recent advances and summarize the current state of the science.

Eight million years of maintained heterozygosity in chromosome homologs of cercopithecine monkeys

In the Cercopithecini ancestor two chromosomes, homologous to human chromosomes 20 and 21, fused to form the Cercopithecini specific 20/21 association. In some individuals from the genus Cercopithecus, this association was shown to be polymorphic for the position of the centromere, suggesting centromere repositioning events. We set out to test this hypothesis by defining the evolutionary history of the 20/21 association in four Cercopithecini species from three different genera. The marker order of the various 20/21 associations was established using molecular cytogenetic techniques, including an array of more than 100 BACs. We discovered that five different forms of the 20/21 association w…

Chromosome painting of the pygmy tree shrew shows that no derived cytogenetic traits link primates and scandentia.

We hybridized human chromosome paints on metaphases of the pygmy tree shrew (<i>Tupaia minor</i>, Scandentia). The lack of the ancestral mammalian 4/8 association in both Primates and Scandentia was long considered a cytogenetic landmark that phylogenetically linked these mammalian orders. However, our results show that the association 4/8 is present in <i>Tupaia </i>along with not previously reported associations for 1/18 and 7/10. Altogether there are 11 syntenic associations of human chromosome segments in the pygmy tree shrew karyotype: 1/18, 2/21, 3/21, 4/8, 7/10, 7/16, 11/20, 12/22 (twice), 14/15 and 16/19. Our data remove any cytogenetic evidence that Scandent…

Multidirectional chromosome painting reveals a remarkable syntenic homology between the greater galagos and the slow loris.

We report on the first reciprocal chromosome painting of lorisoids and humans. The chromosome painting showed a remarkable syntenic homology between Otolemur and Nycticebus. Eight derived syntenic associations of human segments are common to both Otolemur and Nycticebus, indicative of a considerable period of common evolution between the greater galago and the slow loris. Five additional Robertsonian translocations form the slow loris karyotype, while the remaining chromosomes are syntenically equivalent, although some differ in terms of centromere position and heterochromatin additions. Strikingly, the breakpoints of the human chromosomes found fragmented in these two species are apparentl…

WILLIAMS-BEUREN MAPPING IN CALLITHRIX ARGENTATA, CALLICEBUS CUPREUS AND ALOUATTA CARAYA INDICATES DIFFERENT PATTERNS OF CHROMOSOMAL REARRANGEMENTS IN NEOTROPICAL PRIMATES

Human chromosome 7 has a complex syntenic origin. It was divided into two segments in both the ancestral primate karyotype and in Platyrrhini. Apparently, a small segment in the ancestral platyrrhine karyotype was associated with HSA5 and the remainder formed a middle-sized submetacentric. We tested the dynamics of platyrrhine chromosomes by hybridizing the locus specific Willams-Beuren probe (7q 11.23, 450 kb) to chromosomes of representative species from the three families of the New World monkeys recently proposed by molecular genomics: Cebidae, Callithrix argentata (bare ear marmoset or silvery marmoset, 2n = 44); Pitheciidae, Callicebus cupreus [red titi monkey, or coppery monkey, 2n =…

Reciprocal painting and Fission Breakpoints to analyse the phylogenetic relationshi among Titi monkeys.