Alongkoad Tanomtong

Flying lemurs – The 'flying tree shrews'? Molecular cytogenetic evidence for a Scandentia-Dermoptera sister clade

BackgroundFlying lemurs or Colugos (order Dermoptera) represent an ancient mammalian lineage that contains only two extant species. Although molecular evidence strongly supports that the orders Dermoptera, Scandentia, Lagomorpha, Rodentia and Primates form a superordinal clade called Supraprimates (or Euarchontoglires), the phylogenetic placement of Dermoptera within Supraprimates remains ambiguous.ResultsTo search for cytogenetic signatures that could help to clarify the evolutionary affinities within this superordinal group, we have established a genome-wide comparative map between human and the Malayan flying lemur (Galeopterus variegatus) by reciprocal chromosome painting using both human and G. variegatus chromosome-specific probes. The 22 human autosomal paints and the X chromosome paint defined 44 homologous segments in the G. variegatus genome. A putative inversion on GVA 11 was revealed by the hybridization patterns of human chromosome probes 16 and 19. Fifteen associations of human chromosome segments (HSA) were detected in the G. variegatus genome: HSA1/3, 1/10, 2/21, 3/21, 4/8, 4/18, 7/15, 7/16, 7/19, 10/16, 12/22 (twice), 14/15, 16/19 (twice). Reverse painting of G. variegatus chromosome-specific paints onto human chromosomes confirmed the above results, and defined the origin of the homologous human chromosomal segments in these associations. In total, G. variegatus paints revealed 49 homologous chromosomal segments in the HSA genome.ConclusionComparative analysis of our map with published maps from representative species of other placental orders, including Scandentia, Primates, Lagomorpha and Rodentia, suggests a signature rearrangement (HSA2q/21 association) that links Scandentia and Dermoptera to one sister clade. Our results thus provide new evidence for the hypothesis that Scandentia and Dermoptera have a closer phylogenetic relationship to each other than either of them has to Primates.

Chromosomal rearrangements and karyotype evolution in carnivores revealed by chromosome painting

Chromosomal evolution in carnivores has been revisited extensively using cross-species chromosome painting. Painting probes derived from flow-sorted chromosomes of the domestic dog, which has one of the most rearranged karyotypes in mammals and the highest dipoid number (2n=78) in carnivores, are a powerful tool in detecting both evolutionary intra- and inter-chromosomal rearrangements. However, only a few comparative maps have been established between dog and other non-Canidae species. Here, we extended cross-species painting with dog probes to seven more species representing six carnivore families: Eurasian lynx (Lynx lynx), the stone marten (Martes foina), the small Indian civet (Viverricula indica), the Asian palm civet (Paradoxurus hermaphrodites), Javan mongoose (Hepestes javanicas), the raccoon (Procyon lotor) and the giant panda (Ailuropoda melanoleuca). The numbers and positions of intra-chromosomal rearrangements were found to differ among these carnivore species. A comparative map between human and stone marten, and a map among the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis), stone marten and human were also established to facilitate outgroup comparison and to integrate comparative maps between stone marten and other carnivores with such maps between human and other species. These comparative maps give further insight into genome evolution and karyotype phylogenetic relationships among carnivores, and will facilitate the transfer of gene mapping data from human, domestic dog and cat to other species.

First detailed reconstruction of the karyotype of Trachypithecus cristatus (Mammalia: Cercopithecidae)

BackgroundThe chromosomal homologies of human (Homo sapiens = HSA) and silvered leaf monkey (Trachypithecus cristatus = TCR) have been previously studied by classical chromosome staining and by fluorescence in situ hybridization (FISH) applying chromosome-specific DNA probes of all human chromosomes in the 1980s and 1990s, respectively.ResultsHowever, as the resolution of these techniques is limited we used multicolor banding (MCB) at an ~250-band level, and other selected human DNA probes to establish a detailed chromosomal map of TCR. Therefore it was possible to precisely determine evolutionary conserved breakpoints, orientation of segments and distribution of specific regions in TCR compared to HSA. Overall, 69 evolutionary conserved breakpoints including chromosomal segments, which failed to be resolved in previous reports, were exactly identified and characterized.ConclusionsThis work also represents the first molecular cytogenetic one characterizing a multiple sex chromosome system with a male karyotype 44,XY1Y2. The obtained results are compared to other available data for old world monkeys and drawbacks in hominoid evolution are discussed.

Comprehensive characterization of evolutionary conserved breakpoints in four New World Monkey karyotypes compared to Chlorocebus aethiops and Homo sapiens.

Comparative cytogenetic analysis in New World Monkeys (NWMs) using human multicolor banding (MCB) probe sets were not previously done. Here we report on an MCB based FISH-banding study complemented with selected locus-specific and heterochromatin specific probes in four NWMs and one Old World Monkey (OWM) species, i.e. in Alouatta caraya (ACA), Callithrix jacchus (CJA), Cebus apella (CAP), Saimiri sciureus (SSC), and Chlorocebus aethiops (CAE), respectively. 107 individual evolutionary conserved breakpoints (ECBs) among those species were identified and compared with those of other species in previous reports. Especially for chromosomal regions being syntenic to human chromosomes 6, 8, 9, 10, 11, 12 and 16 previously cryptic rearrangements could be observed. 50.4% (54/107) NWM-ECBs were colocalized with those of OWMs, 62.6% (62/99) NWM-ECBs were related with those of Hylobates lar (HLA) and 66.3% (71/107) NWM-ECBs corresponded with those known from other mammalians. Furthermore, human fragile sites were aligned with the ECBs found in the five studied species and interestingly 66.3% ECBs colocalized with those fragile sites (FS). Overall, this study presents detailed chromosomal maps of one OWM and four NWM species. This data will be helpful to further investigation on chromosome evolution in NWM and hominoids in general and is prerequisite for correct interpretation of future sequencing based genomic studies in those species.

Molecular Cytogenetic Analysis of One African and Five Asian Macaque Species Reveals Identical Karyotypes as in Mandrill

Background: The question how evolution and speciation work is one of the major interests of biology. Especially, genetic including karyotypic evolution within primates is of special interest due to the close phylogenetic position of Macaca and Homo sapiens and the role as in vivo models in medical research, neuroscience, behavior, pharmacology, reproduction and Acquired Immune Deficiency Syndrome (AIDS). Materials & Methods: Karyotypes of five macaque species from South East Asia and of one macaque species as well as mandrill from Africa were analyzed by high resolution molecular cytogenetics to obtain new insights into karyotypic evolution of old world monkeys. Molecular cytogenetics applying human probes and probe sets was applied in chromosomes of Macaca arctoides, M. fascicularis, M. nemestrina, M. assamensis, M. sylvanus, M. mulatta and Mandrillus sphinx. Established two- to multicolor-fluorescence in situ hybridization (FISH) approaches were applied. Locus-specific probes, whole and partial chromosome paint probes were hybridized. Especially the FISH-banding approach multicolor-banding (MCB) as well as probes oriented towards heterochromatin turned out to be highly efficient for interspecies comparison. Conclusion: Karyotypes of all seven studied species could be characterized in detail. Surprisingly, no evolutionary conserved differences were found among macaques, including mandrill. Between the seven here studied and phenotypically so different species we expected several via FISH detectable karyoypic and submicroscopic changes and were surprised to find none of them on a molecular cytogenetic level. Spatial separation, may explain the speciation and different evolution for some of them, like African M. sylvanus, Mandrillus sphinx and the South Asian macaques. However, for the partially or completely overlapping habitats of the five studied South Asian macaques the species separation process can also not be deduced to karyotypic separation.