Comparative Chromosome Mapping of Musk Ox and the X Chromosome among Some Bovidae Species

Abstract

Bovidae, the largest family in Pecora infraorder, are characterized by a striking variability in diploid number of chromosomes between species and among individuals within a species. The bovid X chromosome is also remarkably variable, with several morphological types in the family. Here we built a detailed chromosome map of musk ox (Ovibos moschatus), a relic species originating from Pleistocene megafauna, with dromedary and human probes using chromosome painting. We trace chromosomal rearrangements during Bovidae evolution by comparing species already studied by chromosome painting. The musk ox karyotype differs from the ancestral pecoran karyotype by six fusions, one fission, and three inversions. We discuss changes in pecoran ancestral karyotype in the light of new painting data. Variations in the X chromosome structure of four bovid species nilgai bull (Boselaphus tragocamelus), saola (Pseudoryx nghetinhensis), gaur (Bos gaurus), and Kirk’s Dikdik (Madoqua kirkii) were further analyzed using 26 cattle BAC-clones. We found the duplication on the X in saola. We show main rearrangements leading to the formation of four types of bovid X: Bovinae type with derived cattle subtype formed by centromere reposition and Antilopinae type with Caprini subtype formed by inversion in XSB1.

Evolutionary rearrangements of X chromosomes in voles (Arvicolinae, Rodentia)

“…Although there was no indication of any prevailing type of rearrangements between groups, the results showed that X chromosomes of voles, not only of the genus Microtus, frequently undergo intrachromosomal rearrangements. Such high variability in X chromosome morphology generated by intrachromosomal rearrangements was previously documented only for some ruminants 11,12 . As for arvicoline rodents, ruminants are also characterized by an increased rate of karyotype evolution among mammals.…”

“…However, there are well known cases when the X chromosome, both with respect to gene content and marker order 10 , is not conserved. The X chromosomes of a significant number of mouse-like rodents (Myomorpha) and cetartiodactyls are clearly rearranged and subject to both intrachromosomal and interchromosomal rearrangements [11][12][13][14] . The reasons why some taxa escape X chromosome conservatism are not clear.…”

The Cytogenetics of the Water Buffalo: A Review

“…The Robertsonian translocation (rob) has been the most common chromosomal mechanism characterizing the evolutionary history of many autosome chromosomes from bovid species. Still, complex chromosome rearrangements are also followed by sex chromosomes [ 36 , 57 ].…”

“…These chromosome changes have been the result of karyotype evolution, determining several species. Furthermore, the study of chromosomes has been mainly used in animal cytogenetics to (1) verify the relationship between chromosome abnormalities and fertility [ 3 , 4 , 5 , 6 , 7 ]; (2) physically map both type I (expressed sequences) and type II (SSRs, microsatellite marker, STSs) loci, especially using fluorescence in situ hybridization (FISH) techniques [ 8 , 9 , 10 , 11 , 12 ]; (3) correctly identify the chromosomes involved in chromosomal abnormalities via chromosome banding techniques [ 13 , 14 ]; (4) reveal chromosome rearrangements occurring in some chromosomal abnormalities, especially using both FISH mapping [ 15 , 16 , 17 ] and comparative genome hybridization array (aCGH) techniques [ 18 , 19 ]; (5) compare related and unrelated genomes by using the Zoo-FISH technique [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ], centromeric SAT sequences by FISH mapping [ 29 ], or detailed FISH mapping along chromosomes [ 30 , 31 , 32 , 33 , 34 , 35 , 36 ]; and (6) test the genome stability of several bovids, including the river buffalo, with both in vitro and in vivo (natural) exposure to potential mutagens [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ], or affected by limb malformation...…”

The Plasticity of Genome Architecture

“…In their study, the authors provide a comprehensive view of this species combining conventional and molecular cytogenetic methods, single chromosome DNA sequencing, and breeding experiments, revealing the chromosome segregation pattern as well as the reproductive performance of different karyomorphs. Finally, Proskuryakova et al [28] illustrate how, by comparative chromosome mapping, it is possible to identify variations in the X chromosome structure of four bovid species: nilgai bull (Boselaphus tragocamelus), saola (Pseudoryx nghetinhensis), gaur (Bos gaurus), and Kirk's Dikdik (Madoqua kirkii).…”