Developmental failure of hybrid embryos originated after fertilization of bovine oocytes with ram spermatozoa

Abstract

The developmental ability of hybrid zygotes, produced by in vitro fertilization of in vitro matured bovine oocytes with ram sperm, was evaluated by gross morphology, autoradiographic detection of (5‐3H) uridine incorporation, and fine structure morphology. Fertilization was successful in 83% of bovine oocytes inseminated with bull sperm (control embryos) compared with 67% of bovine oocytes inseminated with ram sperm (hybrid embryos) and in both cases appeared two regularly developed pronuclei. Two‐cell embryos were transferred to ewe oviducts and allowed to develop to the 8‐cell stage. Although the ability of hybrid embryos to reach 8‐cell stage was similar to that of control embryos, in nuclei of hybrid embryos the transition from maternal to embryonic genome control assessed according to the onset of RNA synthesis indicated the differences in the frequency of labelled nuclei and intensity of their labelling. In hybrid embryos these parameters were remarkably lower and may reflect the developmental failure of hybrid embryos. These observations are consistent with delay or inefficient reactivation of the embryonic genome in the hybrid embryos. Mol. Reprod. Dev. 48:344–349, 1997. © 1997 Wiley‐Liss, Inc.

In vitro production of cattle-water buffalo (Bos taurus - Bubalus bubalis) hybrid embryos

“…In all these cases the hybrid status of the zygotes and embryos was confirmed at the pronuclear stage by virtue of a sperm tail attached to one of the pronuclei, and at later stages of development by the presence of 3 to 5 bi-armed chromosomes in hybrid blastocysts (bi-armed chromosomes in excess of one in the embryo spreads serve as unequivocal proof of their status as hybrids). Developmental arrest at specific post-fertilisation stages has been detected as a consistent feature of cattle-sheep hybrid embryos (Kelk, 1997;Slavik et al, 1997). In the present study, 40.5% of B × C embryos were arrested at the morula stage while the proportion of other embryos arrested at this stage was lower (20.3%, 22.8% and 26.2%, respectively, for C × B, C × C and B × B embryos).…”

“…However, serum and calcium lactate supplementation did not improve the reciprocal scheme (Kelk, 1997). Similarly, Slavik et al (1997) found that in vivo culture of 2-cell stage cattle-sheep hybrid embryos was not able to overcome the developmental block in such embryos. These observations would suggest that the large proportion of B × C embryos blocked at the morula stage probably reflects their inherent inability to overcome this developmental block rather than an in vitro induced developmental failure.…”

“…When cattle are inseminated with semen from sheep, or sheep inseminated with semen from cattle, fertilisation does not occur. Yet, cattle and sheep gametes undergo fertilisation and the resulting hybrid embryos develop to the 8-cell stage (Kelk, 1997;Slavik et al, 1997).…”

Faster Fertilization Rate in Conspecific Versus Heterospecific Matings in House Mice

“…When females mate with both conspecific and heterospecific males, the resulting progeny are often biased towards conspecific sires (Hewitt et al 1989;Gregory and Howard 1994;Robinson et al 1994;Wade et al 1994;Price 1997;Howard et al 1998;Howard 1999;Dixon et al 2003;Chang 2004;Fricke and Arnqvist 2004;Rugman-Jones and Eady 2007). Faster conspecific fertilization has been observed in many vertebrates (Gray 1958;Lopyrin and Loginova 1963;Gray 1972;Hanada and Chang 1972;Maddock and Dawson 1974;West et al 1977;Fukuda et al 1979;Lambert 1984;Roldan et al 1985;Roldan and Yanagimachi 1989;Slavík et al 1997;Kouba et al 2001;Kochhar et al 2002;Birkhead and Brillard 2007), but never in species pairs known to hybridize in nature. In fact, copulation is mechanically impossible in most vertebrate studies, so the potential for differences in fertilization rate to contribute to reproductive isolation in nature remains unknown.…”

Postmating sexual conflict and female control over fertilization during gamete interaction

“…However, one limitation of these comparative studies on marine invertebrates is that speciation is largely complete for many of the species, with little to no hybridization occurring in the wild . Faster conspecific (versus heterospecific) fertilization rates have been documented in vertebrates (e.g., mammals; birds), but only a single account exists for species that hybridize in nature, that is, M. m. musculus and M. m. domesticus . IVF in internal fertilizers can be useful in isolating mechanisms that specifically influence fertilization as it excludes the FRT and seminal proteins, which affect sperm function and influence how females respond to sperm .…”