Gender preselection in cattle with intracytoplasmically injected, flow cytometrically sorted sperm heads.
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We investigated the development to the blastocyst and subsequent live-offspring stages of in vitro-matured bovine oocytes intracytoplasmically injected with flow cytometrically sorted bull sperm heads. Bull sperm heads, prepared by ultrasound sonication, were distinguished and sorted on the basis of their relative DNA contents using a flow cytometer/cell sorter modified for sorting sperm. By fluorescence in situ hybridization, the proportion of sperm confirmed as having Y specific DNA in the fraction sorted for the Y sperm was 82%. Injection with single sorted sperm heads of in vitro-matured oocytes (cultured for 24 h) resulted in 46.6% cleavage and 6.9% blastocyst development rates. Embryo transfer of 48 blastocysts (Days 7-8) to recipients (one per recipient) resulted in 20.8% pregnancy and 20.8% normal live offspring production rates. The birth of 8 male and 2 female calves represents an 80% sex preselection accuracy rate. (+info)
Fertility rates in Denmark in relation to the sexes of preceding children in the family.
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Analysis of the effect of sex combination of previously born children in the family on fertility rates was performed for 363,373 Danish families comprising a total of 613,900 children, to address the questions of sex preference and combination preference. The fertility rates were stratified by parental age, period and latency time to the next child, and fertility rate ratios were estimated using multiplicative Poisson regression models. Our results demonstrate a strong preference for a balanced composition of sexes in Danish families. In families with two or three children the highest fertility rates were seen in families who had same-sexed children. The lowest fertility rates were in families with two children of identical sex followed by a child of the opposite sex. A moderate sex preference for girls was indicated by higher fertility rates in two-boy families than in two-girl families. (+info)
In vitro production of sexed embryos for gender preselection: high-speed sorting of X-chromosome-bearing sperm to produce pigs after embryo transfer.
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The objectives for the present experiments were to apply sperm sexing technology to an in vitro production system with porcine oocytes obtained from slaughterhouse material. On six experimental days, ovaries were obtained from an abattoir, and cumulus-oocyte-complexes were matured in vitro. Semen was collected from mature boars of proven fertility and was sorted for X-chromosome-bearing sperm, using the Beltsville Sperm Sexing Technology incorporating the use of high-speed sorting. A total of 5,378 oocytes were submitted for in vitro fertilization (IVF). Of these, 559 ova were stained for cytogenetic analysis 18 h after IVF. From the remaining 4,819 ova, 1,595 cleaved, and 1,300 of the cleaved embryos were transferred into 26 synchronized recipients (5 control gilts for unsorted sperm, 21 gilts for X-sorted sperm). In a test of two fertilization media (FERT-A vs FERT-B) higher cleavage rates (P<.05) were obtained when FERT-B was used as a fertilization medium for unsorted (43.4+/-5.1%) and sorted sperm (43.1+/-1.1%;), whereas in FERT-A unsorted sperm gave a cleavage rate of 17.9+/-4.4% and sorted sperm gave 30.4+/-1.4%. Additionally, cleavage rates were higher (P<.05) after fertilization with sorted sperm vs unsorted sperm, independent of fertilization medium. Cytogenetic analysis of ova revealed that more oocytes with unsorted than with sorted sperm remained in Metaphase 2 arrest (P<.05). This was also independent of the fertilization medium. Monospermic fertilization rates were the same for IVF with unsorted or sorted sperm, independent of the fertilization system, except FERT-A with unsorted sperm (P<.05). Polyspermic fertilization rates were highest in FERT-B (37.6+/-6.6). A total of 57 pigs were born from nine litters. Six litters from sexed sperm (X-sorted) produced 33 females (97%) and one male. Three litters from control transfers produced 23 pigs, 11 of which were female (48%). The sex ratio of the offspring was predicted based on the sort reanalysis of the sorted sperm for DNA content. (+info)
Sex selection and preimplantation diagnosis: a response to the Ethics Committee of the American Society of Reproductive Medicine.
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In its recent statement 'Sex Selection and Preimplantation Genetic Diagnosis', the Ethics Committee of the American Society of Reproductive Medicine concluded that preimplantation genetic diagnosis for sex selection for non-medical reasons should be discouraged because it poses a risk of unwarranted gender bias, social harm, and results in the diversion of medical resources from genuine medical need. We critically examine the arguments presented against sex selection using preimplantation genetic diagnosis. We argue that sex selection should be available, at least within privately funded health care. (+info)
The Brussels' experience of more than 5 years of clinical preimplantation genetic diagnosis.
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This paper describes the 5 years' experience of preimplantation genetic diagnosis (PGD) at the Brussels Free University. Our first PGD was carried out in February 1993. Up to October 1998, we carried out 183 PGD cycles on fresh cleavage embryos of 92 couples for 25 different conditions. Patients were treated for autosomal recessive (n = 39), autosomal dominant (n = 65) and X-linked recessive (n = 47) monogenic disorders as well as for autosomal structural aberrations (n = 10), sex chromosome numerical and structural aberrations (n = 21) and a combination of the two latter (n = 1). Specific diagnosis was carried out by polymerase chain reaction (n = 108). Fluorescence in-situ hybridization was used for sexing (n = 64) and structural aberrations (n = 11). We transferred 1.6 +/- 1.1 embryos per cycle, resulting in an implantation rate of 12.0% per replaced embryo. Ongoing pregnancies were achieved in 29 cycles, i.e. 23 singletons, five twins and one dichorionic triplet with an acardius acranius. The ongoing pregnancy rates per cycle, per transfer and per couple were 16.4, 19.9 and 31.5% respectively. While 28 ongoing pregnancies resulted in the births of 34 infants, one pregnancy was terminated after misdiagnosis. The results of 24 PGD were confirmed by prenatal diagnosis or after birth while no information was available in four pregnancies. Our series demonstrates that PGD is a feasible technique by which to avoid the birth of genetically affected children to couples at risk. (+info)
Disruptive sexual selection against hybrids contributes to speciation between Heliconius cydno and Heliconius melpomene.
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Understanding the fate of hybrids in wild populations is fundamental to understanding speciation. Here we provide evidence for disruptive sexual selection against hybrids between Heliconius cydno and Heliconius melpomene. The two species are sympatric across most of Central and Andean South America, and coexist despite a low level of hybridization. No-choice mating experiments show strong assortative mating between the species. Hybrids mate readily with one another, but both sexes show a reduction in mating success of over 50% with the parental species. Mating preference is associated with a shift in the adult colour pattern, which is involved in predator defence through Mullerian mimicry, but also strongly affects male courtship probability. The hybrids, which lie outside the curve of protection afforded by mimetic resemblance to the parental species, are also largely outside the curves of parental mating preference. Disruptive sexual selection against F(1) hybrids therefore forms an additional post-mating barrier to gene flow, blurring the distinction between pre-mating and post-mating isolation, and helping to maintain the distinctness of these hybridizing species. (+info)
Why sex selection should be legal.
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Reliable medically assisted sex selection which does not involve abortion or infanticide has recently become available, and has been used for non-medical reasons. This raises questions about the morality of sex selection for non-medical reasons. But reasonable people continue to disagree about the answers to these questions. So another set of questions is about what the law should be on medically assisted sex selection for non-medical reasons in the face of reasonable disagreement about the morality of sex selection. This paper sketches a way of thinking about what the law should be, and concludes, contrary to what the law is in many places, that medically assisted sex selection for non-medical reasons ought to be legal. (+info)
Preimplantation sex selection for family balancing in India.
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We describe our experience with the use of embryo biopsy and fluorescent in-situ hybridization (FISH) in order to sex embryos for the purpose of family balancing in a private IVF clinic in India from April 1999-April 2001. Embryos were biopsied and analysed on day 3, cultured in sequential media, and then transferred on day 4 or day 5 after morphological selection of the best embryos. From a total of 42 cycles started, we achieved 14 clinical pregnancies and have had nine live births so far with five ongoing pregnancies. This is the first report of the use of preimplantation sex selection for family balancing in India, where couples place a premium on having baby boys, and the social and ethical aspects of the use of this technology in this setting are discussed. (+info)