> ik heb dat misschien al, heb je het op file (of scan)? dan kan
> je het mailen,
> dan sparen we het milieu een beetje zonder info te verliezen
Ik zou best eens in jouw boekenkast willen neuzen, volgens mij is dat onwijs interessant. Ik ga even op zoek of ik het digitaal heb dan stuur ik het hier wel heen mischien vindt iemand anders het ook wel interessant. Het volgende onderzoek ken je mischien nog niet kwam al zoekend op de pc nog tegen. Voor andere mensen mischien ook een kleine les in het verschil tussen rassen en soorten in het Equus dierenrijk.
The Caspian horse karyotype has been done 2 times by Dr.Monazah & Pandit 1979, Mehrannezhad & me on 2003.On both of them there were some 65 Chromosome number Caspians.I shared this idea with Dr.Cothran and he was interested on it by as he always used the hair samples(and it is necessary to use white blood cells for karyoytyping) it was not possible for him to do it. So i prepared a project and shared it to some of the universities to do it.I have applied and searching for the fundings of this big project to start it by new year.
the summary and literature review of this project will help you to know what is going on now:
Caspian horse Karyotype project:
The horse (Equus caballus) is a member of the order Perissodactyla of odd toed mammals made up by the three families:
Equidae (two horse species, three hemione species, two donkey species and at least three zebra species), Rhinocerotidae (five species) and Tapiridae (four species). Among the Perissodactyla, only three species have been domesticated: the horse (Equus caballus) and the two donkeys (Equus asinus and Equus africanus somalicus).
Hybrids have been produced for most species pairs among the Equidae, however the hybrids are almost always infertile. The best known hybrid is the cross of the horse mare with a donkey jack to produce a mule. Mules were prized for their intelligence and vigor and played a major role in agriculture and industry. The reason for the infertility is probably differences in genome organization between the species of Equidae and failure of meiosis within hybrid animals.
Chromosome numbers range from 33 pairs for Equus przewalskii (Mongolian Wild Horse) to 16 pairs for the Equus zebra hartmannae (Hartmann’s zebra, a.k.a., Mountain zebra). These species diverged 3-5 million years ago, so chromosome evolution has been relatively rapid for this family. Comparative mapping studies indicate that chromosome evolution among the Equidae has probably been the result of chromosome fusion and centromere repositioning (Lear, 2005
The living wild horse species to day are found only in Asia and Africa. Chromosomal morphology and numbers in the living members of the genus Equus present a heterogeneous picture. As an illustration of this diversity, we can remind the Chromosome number of some species and some subspecies as:
Species Common name Chromosome
E.przewalskii Przewalski’s wild horse 66
E.caballus Domestic horse 64(Caspian horse 65)
E.asinus Domestic ass (donkey) 62-63
E.hemionus onager Persian wild ass (onager) 55-56
(Ryder et al.1987, Benirschke &Ryder 1985, Bowling&Million 1988)
Numerical as well as morphological chromosomal differences show that the specification process in equines involved exchanges of DNA sequence blocks in many chromosomes. Despite the array of numerical and structural differences, several prominent chromosomal similarities are found, particularly within the horses, the asses and the half-asses (hemiones).
As the genetic of all domestic breeds of horses is nearly identified. Horses of all breeds have the same number, size and shape of chromosomes (Except the Caspian miniature horse). The current standard karyotype for the horses was defined by Richer and colleagues (1990).It consists of 13 meta- and submetacentric (bi-armed) and 18 acrocentric pairs of autosomes, plus a large submetacentric X and a small acrocentric Y.
Przewalski’s horse has extensive chromosome homology with the domestic horse. Two acrocentric pairs in E przewalski appear to be combined in one metacentric chromosome (chromosome 5) in the E.caballus karyotype (E. Ahrens, G. Stranzinger 2005). A Robertsonian translocation event can explain the difference between the two species; either fusion or fission is possible, assuming one species is derived from the other, depending on which arrangement is ancestral.
Cytogenetic map: The equine gene mapping community has published extensively to rapidly expand the cytogenetic map in the horse (e.g., Breen et al. 1997; Goddard et al. 2000; Lear et al. 2001; Lindgren et al., 2001; Mariat et al. 2001; Raudsepp et al. 2001; Milenkovic et al. 2002; Chowdhary et al. 2002; Raudsepp et al. 2002; Chowdhary et al. 2003; Lee et al. 2004; Raudsepp et al. 2004; Raudsepp et al. 2004; Brinkmeyer-Langford et al. 2005; Gustafson-Seabury et al. 2005,).
All breeds within the domestic horse species have the same chromosome number (2n=64), with the exception that 2n=65 has been reported for some Caspian horses (Hatami-Monazah & Pandit 1979, Mehrannezhad & Dordari 2003). The extra chromosome could be explained as centric fission of a metacentric chromosome into two acrocentrics, although the authors suggested that the origin followed natural hybridization between domestic horses and Przewalski’s horse. In the cattle and pigs lowered fertility can occur through early embryonic loss from chromosomally unbalanced gametes .Phenotypically normal parents heterozygous for chromosomal fusion between acrocentric chromosomes have the potential for producing genetically unbalanced gametes during meiosis? Translocation heterozygotes are reported among the Caspian horses but have not been directly implicated in infertility problems in this breed (Hatami-Monazah & Pandit 1979).
Power (1991) described an 11 years old Thoroughbred mare with only two foals in eight years of breeding that had abnormal Karyotype consisting of heterozygosity for a balanced reciprocal translocation between two of the largest autosomes. Eight years old fertile Thoroughbred stallion with a balanced tandem translocation between chromosomes 1 and 30 was reported by Long (1994).Mares bred to this stallion would become pregnant, but lose the pregnancy in an early embryonic death. The karyotype of 10 mares which showed abnormal fertility due to anoestrus, repeat breeding, abortion or underdevelopment of internal reproductive organs showed: X chromosome monosomy was diagnosed in five mares; 63,X karyotype in pure form in one mare, and 63,X/64,XX karyotype in the form of mosaic cell lines in the other four mares with a low (3.5-9%) proportion of lines with an abnormal set of chromosomes by Bugno et al (2003).
Comparative chromosomal studies of E. caballus (ECA) and E. przewalskii (EPR) in a female F1 hybrid by Ahrens, E. & Stranzinger, G. (2005)showed that the karyotype of E. caballus and E. przewalskii differ solely by one Robertsonian translocation (ECA 5 =EPR 23 + EPR 24).
So the aim of this research could be to clear that if we join 2 Caspian horse with 65 chromosome number will join to each other and we can separate the semen of the stallion which will have the 33 chromosomes number and the ovum of the same chromosome (33) the next generation will be 66 ( like the E. przewalskii )or not and will be able to survive and if it will be sterile or not.
Ik ben er nog niet uit of we gaan meewerken of niet ik ben niet zo op het blootstellen van mijn paarden aan experimenten.
Warboel
