Genetic aspects of equids with particular reference to their hybrids

Benirschke, Kurt; Ryder, Oliver A.

doi:10.1111/j.2042-3306.1985.tb04583.x

Cited by 9 publications

(5 citation statements)

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“…Mules have been used by humans since ancient times, and while usually sterile, there are reported cases of fertile individuals . Besides reports of recent hybrids between equid species like zebra and horse, there is evidence for admixture events within domesticated equids that lie further back in time: For instance, all present‐day domesticated horses carry around 13% of ancestry from a now extinct horse lineage, which is absent in Prezwalski's horses . Ancient gene flow between equid species has been observed, despite divergent karyotypes (16–33 chromosome pairs), involving kiangs, donkeys, asses, and zebra species .…”

Section: Domesticated Speciesmentioning

confidence: 99%

Admixture in Mammals and How to Understand Its Functional Implications

2019

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Admixture, the genetic exchange between differentiated populations appears to be common in the history of species, but has not yet been comparatively studied across mammals. This limits the understanding of its mechanisms and potential role in mammalian evolution. The authors want to summarize the current knowledge on admixture in non-human primates, and suggest that it is important to establish a comparative framework for this phenomenon in humans. Genetic observations in domesticated mammals and their wild counterparts are discussed, and a brief global overview on other clades is presented. Based on this, some of the consequences of gene flow, including incompatibilities and their genomic footprint, as well as adaptive introgression are discussed, and suggestions for a functional genomics approach are made. It is proposed that the field is moving beyond descriptive observations in single species, to a comprehensive analysis of admixture and its impact. Admixture is becoming an integral part of mammalian evolution.

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Section: Domesticated Speciesmentioning

confidence: 99%

Admixture in Mammals and How to Understand Its Functional Implications

2019

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“…The mammalian family Equidae is unusual in that interbreeding and production of viable, though usually infertile offspring is possible between nearly every pair of its member species. A considerable range of hybrid foals have been born in captivity, despite significant chromosomal differences between the parent species (Benirschke & Ryder 1985;Allen & Short 1997). The number of chromosomes in the genus Equus ranges from a high of 66 in Przewalski's Horse to 32 in the Mountain Zebra.…”

Section: Equine Hybridsmentioning

confidence: 99%

Caught between two worlds: genes and environment influence behaviour of plains × Grevy's zebra hybrids in central Kenya

Schieltz

Rubenstein

2015

Animal Behaviour

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Purpose/Objective: New definitions for some dosimetric parameters for use in quality assurance of flattening filter free (FFF) beams generated by medical linear accelerators have been suggested. The present study aims to validate these suggestions and to propose possible reference levels. Materials and Methods:The main characteristics of FFF photon beams were described in terms of: field size, penumbra, unflatness, slope and peak-position parameters. Data were collected for 6 and 10 MV-FFF beams from three different Varian TrueBeam linacs, and a Varian Clinac iX upgraded to FFF capability for its 6 MV. Measurements were performed with a 2D-array (Starcheck system from PTW-Freiburg), with a linear array (LA48 system from PTW-Freiburg) and with the portal dosimetry method GLAaS utilizing the build-in portal imager of TrueBeam.Results: All the parameters suggested to characterize the FFF beams were measured and evaluated Little variation was observed among the different linacs. Referring to two reference field sizes of 10x10 and 20x20cm 2 , at SDD=100cm and d=d max , from the portal imaging data converted into dose map with the GLAaS method, the following results were obtained, averaged on X and Y profiles. Field size: 9.95±0.02 cm and 19.98±0.03 cm (including allenergies. Penumbra: 2.7±0.3 mm and 2.9±0.3 mm for 6MV-FFF; 3.1±0.2 mmand 3.3±0.3 for 10MV-FFF. Unflatness: 1.11±0.01 and 1.25±0.01 for 6MV-FFF; 1.21±0.01 and1.50±0.01 for 10MV-FFF. Slope: 0.320±0.020 %/mm and 0.43±0.015 %/mm for 6MV-FFF; 0.657±0.023%/mm and 0.795±0.017 %/mm for 10MV-FFF. Peak Position: -0.2±0.2 mm and -0.4±0.2 mm for 6MV-FFF; -0.3±0.2 mm and 0.7±0.3 mmfor 10MV-FFF. Results would depend upon measurement depth. With thresholds set to at least 95% confidence level from the measured data, and to account for possible variations between detectors and methods and experimental settings, a tolerance set of: 1 mm for field size and penumbra, 0.04 for unflatness, 0.1 %/mm for slope and 1 mm for peak position could be proposed from our data. Conclusions:The parameters proposed to characterize the FFF profiles (in particular the unflatness, the slope and the peak position) appear to be a viable solution for routine checks, also presenting strong similarity to the conventional parameters used for flattened beams. The results from three different TrueBeams and a Clinac-iX suggested the robustness of the methods and the possibility to use general tolerances for the parameters. The data suggested also the reproducibility of beam characteristics among different systems (of the same vendor) and could therefore be possibly generalized.Purpose/Objective: A new method for IMRT verification with EBT3 has been developed, avoiding the need of a previous calibration. Performing a single scan gives the possibility to obtain results in less than one hour and avoids environmental and interscan variability. We have developed a method to evaluate measurements of two-dimensional dose distributions following the protocol described by Lewis et al, without the need of a prev...

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“…In general, interspecies gestation is less successful than intraspecies gestation (Bernirschke and Ryder 1985;Skidmore et al 1999). For this reason, the aim of this study was to clarify the importance of MRP in this phenomenon, which is reported for in vitro derived hybrid Bighorn sheep embryos for the first time.…”

Section: Discussionmentioning

confidence: 95%

Identification of novel variants of interferon-tau gene in Bighorn sheep (Ovis canadensis mexicana), Pelibuey sheep (Ovis aries) and its expression in hybrid blastocysts (Ovis canadensis × Ovis aries)

et al. 2012

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Palma-Irizarry, M., Damian-Matsumura, P., Betancourt, M., Romo, S., Perales, G., Lagunas-Martínez, A., Madrid-Marina, M. V., Mejía, O. and Ducolomb, Y. 2012. Identification of novel variants of interferon-tau gene in Bighorn sheep ( Ovis canadensis mexicana ), Pelibuey sheep ( Ovis aries ) and its expression in hybrid blastocysts ( Ovis canadensis×Ovis aries ). Can. J. Anim. Sci. 92: 275–283. The major signal for maternal recognition of pregnancy (MRP) in ruminants is interferon-tau (IFNT). Four novel sequences of the IFNT gene were isolated from genomic DNA obtained from blood samples of Bighorn, Pelibuey or the hybrid ewes. The deduced amino acid sequence of the hybrid ewe showed 100% identity with one Bighorn sheep IFNT sequence, suggesting that this sequence was inherited from Bighorn sheep. The high degree of identity between Pelibuey and Bighorn sheep sequences could be a possible explanation for the successful MRP in some Bighorn hybrid pregnancies. In vivo and in vitro domestic sheep (Ovis aries) and hybrid sheep (Ovis aries×Ovis canadensis) blastocysts were obtained, and IFNT expression was measured by semiquantitative RT-PCR. In vivo and in vitro hybrid blastocysts showed lower expression of IFNT when compared with domestic blastocysts. In conclusion this study showed that there exists an effect of hybridization on IFNT expression and this can affect the MRP.

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Genetic aspects of equids with particular reference to their hybrids

Abstract: Summary This paper gives a brief review of the cytogenetic knowlege of equine species, the chromosomal errors currently known to exist, and an account of the interspecific hybrids that have served man during the 4500 years of domestication of horse and donkey.

Cited by 9 publications

References 50 publications

Admixture in Mammals and How to Understand Its Functional Implications

Admixture in Mammals and How to Understand Its Functional Implications

Caught between two worlds: genes and environment influence behaviour of plains × Grevy's zebra hybrids in central Kenya

Identification of novel variants of interferon-tau gene in Bighorn sheep (Ovis canadensis mexicana), Pelibuey sheep (Ovis aries) and its expression in hybrid blastocysts (Ovis canadensis × Ovis aries)

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