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At least 541 records · Page 30Linked to original sources
PubMed1993

The gene encoding the late nonstructural 36K protein of vaccinia virus is essential for virus reproduction.

Two genetic markers--the thymidine kinase gene of herpes simplex virus, and the beta-galactosidase gene of Escherichia coli--were incorporated into the 36K protein gene (IL1 gene according to the nomenclature of the Copenhagen strain of vaccinia virus; Goebel et al., 1990) from the HindIII-P DNA fragment of the LIVP strain (variant of Lister strain) of vaccinia virus (VV). After recombination of the obtained integration plasmid pVZ64-TK with the VV genome (tk-), it was found that the resultant TK+ viruses were unstable with respect to the Lac+ phenotype. On the basis of hybridization of DNA fragments of selected clones, a scheme for the formation of hybrid viruses is proposed, and an approach to a simple phenotypical discrimination between essential and non-essential genes for VV viability is described.

Animals↗
PubMed2006

The genetic basis of prezygotic reproductive isolation between Drosophila santomea and D. yakuba due to mating preference.

Sexual isolating mechanisms that act before fertilization are often considered the most important genetic barriers leading to speciation in animals. While progress has been made toward understanding the genetic basis of the postzygotic isolating mechanisms of hybrid sterility and inviability, little is known about the genetic basis of prezygotic sexual isolation. Here, we map quantitative trait loci (QTL) contributing to prezygotic reproductive isolation between the sibling species Drosophila santomea and D. yakuba. We mapped at least three QTL affecting discrimination of D. santomea females against D. yakuba males: one X-linked and one autosomal QTL affected the likelihood of copulation, and a second X chromosome QTL affected copulation latency. Three autosomal QTL also affected mating success of D. yakuba males with D. santomea. No epistasis was detected between QTL affecting sexual isolation. The QTL do not overlap between males and females and are not disproportionately concentrated on the X chromosome. There was some overlap in map locations of QTL affecting sexual isolation between D. santomea and D. yakuba with QTL affecting sexual isolation between D. simulans and D. mauritiana and with QTL affecting differences in pigmentation between D. santomea and D. yakuba. Future high-resolution mapping and, ultimately, positional cloning, will reveal whether these traits do indeed have a common genetic basis.

Animals↗
PubMed1987

Reproduction trends and the emergence of moral panic.

Are we witnessing a moral panic or a moral evaluation in the responses to the new reproductive technologies? Locating women in reproductive technology is a particularly powerful way into a discussion of values and consequences, intended or unintended. Twelve areas are isolated for discussion beginning with issues of definition and location: What is reproductive and genetic engineering? and How does human reproduction fit into bio-technological developments generally? Next issues are raised about how the new developments are being shaped ideologically and how they are being promoted by the state. A series of legal issues affecting women, men, children, embryos and fetuses follow. The focus then shifts to the way women are ideologically constructed: Why is there an assumption that woman = mother, and mother = heterosexual married or stable cohabiting woman?--and socially controlled: Why assume technological change in human reproductive processes means the basic subordination of women to men will not alter? The usefulness of the new technologies in relieving involuntary childlessness is then queried which leads on to a questioning of whether these developments are qualitatively different from other technologies used in human reproduction. Futuristic concerns such as the importance of the male pregnancy and the social consequences of fully medicalising human reproduction are raised. The last area to be considered is protest by women and suggested alternative approaches to increase the social visibility and recognition of the needs and interest of women in the current and potential use of the new medical and scientific developments.

Female↗
PubMed1999

Genetic benefits enhance the reproductive success of polyandrous females.

Although it is generally accepted that females can gain material benefits by mating with more than one male, the proposal that polyandry provides genetic benefits remains controversial, largely because direct experimental support is lacking. Here, we report the results of a study testing for genetic benefits to polyandry in the pseudoscorpion Cordylochernes scorpioides. In an experiment that controlled for male mating experience and the number of spermatophores accepted by a female, twice-mated females received either one sperm-packet from each of two different males (the "DM" treatment) or two sperm-packets from a single male (the same male or "SM" treatment). Over their lifetime, DM females gave birth to 32% more offspring than did SM females, primarily because of a significantly reduced rate of spontaneous abortion. This result could not be attributed to male infertility nor to lack of sexual receptivity in males paired with previous mates. Spermatophore and sperm numbers did not differ between males presented with a previous mate and males paired with a new female. Because SM and DM females received the same quantity of ejaculate, it was possible to eliminate material benefits as a contributor to the enhanced reproductive success of DM females. The reduction in embryo failure rate achieved by DM females is most consistent with the genetic incompatibility avoidance hypothesis, i.e., that polyandry enables females to exploit postcopulatory mechanisms for reducing the risk and/or cost of fertilization by genetically incompatible sperm. This study, which rigorously controlled for material benefits and excluded inbreeding effects, demonstrates that polyandry provides genetic benefits that significantly enhance female lifetime reproductive success.

Animals↗
PubMed1982

Genetic polymorphisms and human reproduction: a study of phosphoglucomutase in spontaneous abortion.

Theoretical arguments suggest that variation of metabolic parameters due to genetically determined enzyme polymorphisms may exert important effects on implantation and zygote development. The polymorphic enzyme phosphoglucomutase controlled by locus 1 (PGM1) is a phosphotransferase which plays a key role in carbohydrate metabolism and it is present in high concentrations in placental tissue. The enzyme has been studied in 47 couples with habitual abortion, in 36 women with single episodes of spontaneous abortion, in 48 women with induced abortion, and in control samples of normal individuals from the same population. Among couples with habitual abortion a significant increase of mean survival time of fetuses was observed in PGM1-heterozygote mothers as compared to homozygotes. An increased proportion of couples which may produce the hypothetical PGM1-null phenotype was also observed in habitual abortion, which suggests that homozygosity for PGM10 allele may contribute to fetal loss. Investigations on polymorphic enzymes involved in placental and fetal metabolism may contribute significantly to the problem of genetic etiology of spontaneous abortion.

Abortion, Habitual↗
PubMed2004

Prognostic role of preimplantation genetic diagnosis for aneuploidy in assisted reproductive technology outcome.

BACKGROUND: Preimplantation genetic diagnosis (PGD) for aneuploidy is recommended to couples at risk of generating chromosomally abnormal embryos. The aim of this study was to demonstrate that PGD for aneuploidy has an important role in the prognosis of subsequent treatments. METHODS: A total of 389 couples underwent their first PGD for aneuploidy due to either female age >or=38 years (n = 266) or >or=3 previous unsuccessful cycles (n = 123). After the first PGD followed by an unsuccessful treatment cycle, 141 couples underwent 175 subsequent PGD cycles. These patients were divided into three groups depending on the number of euploid embryos available for transfer in their first PGD cycle: group A included patients where no euploid embryos were diagnosed; group B included patients who had only one euploid embryo; and group C included patients with at least two normal embryos resulting from chromosomal analysis. RESULTS: In subsequent cycles, group A patients underwent significantly fewer transfers (45%) compared with group B (69%, P < 0.05) and group C patients (85%, P < 0.001). The pregnancy rate per transfer was significantly decreased in group A (15%) compared with group B (36%; P < 0.02) and group C (30%; P < 0.03). Accordingly, the live birth rate per patient was significantly lower in group A compared with group C (8.5% versus 30%; P < 0.005). CONCLUSIONS: The outcome of the first PGD for aneuploidy may have a predictive role for subsequent attempts.

Adult↗
PubMed1987

Immunological and genetic factors influencing development and susceptibility to cancer.

The results of a variety of studies on the genetic and immunological aspects of reproduction can be integrated into a hypothesis about the factors that regulate implantation and development and that may also cause an increased susceptibility to cancer. The primary condition for successful reproduction is genetic compatibility between the mating partners: there must be no recessive lethal genes that could act alone or epistatically to cause embryonic or fetal death. Such recessive lethal genes have been identified in the mouse (t-haplotypes) and in the rat (grc), and there is some evidence that they also exist in humans. Immunological factors may modulate the implantation of the fertilized ovum under some circumstances after the genetic condition has been met. The same genetic factors that affect development may also affect susceptibility to cancer. This part of the hypothesis is supported by a number of clinical correlations between congenital defects and a higher incidence of cancer and by the demonstration of an increased susceptibility to the effects of chemical carcinogens in rats carrying the grc.

Animals↗
PubMed2003

A case for the extreme antiquity of recombination.

Recombination is usually assumed to be a mode of reproduction that evolved long after asexual reproduction in response to specific genetic and environmental circumstances. Here the argument is made that recombination was an evolutionary development as ancient as the origins of life. To support this proposition four lines of evidence are given, in particular, the need for primordial genomes to acquire substantial length and to escape from Muller's Ratchet.

Genome↗
PubMed1987

East African cheetahs: evidence for two population bottlenecks?

A combined population genetic and reproductive analysis was undertaken to compare free-ranging cheetahs from east Africa (Acinonyx jubatus raineyi) with the genetically impoverished and reproductively impaired south African subspecies (Acinonyx jubatus jubatus). Like that of their south African counterparts, the quality of semen specimens from east African cheetahs was poor, with a low concentration of spermatozoa (25.3 X 10(6) per ejaculate) and a high incidence of morphological abnormalities (79%). From an electrophoretic survey of the products of 49 genetic loci in A. jubatus raineyi, two allozyme polymorphisms were detected; one of these, for a nonspecific esterase, shows an allele that is rare (less than 1% incidence) in south African specimens. Estimates of polymorphism (2-4%) and average heterozygosity (0.0004-0.014) affirm the cheetah as the least genetically variable felid species. The genetic distance between south and east African cheetahs was low (0.004), suggesting that the development of genetic uniformity preceded the recent geographic isolation of the subspecies. We propose that at least two population bottlenecks followed by inbreeding produced the modern cheetah species. The first and most extreme was ancient, possibly late Pleistocene (circa 10,000 years ago); the second was more recent (within the last century) and led to the south African populations.

Africa, Eastern↗
PubMed1987

A systems analysis approach for studying the effect of reproduction-enhancing biotechnologies on the genetic improvement of beef cattle.

A function is presented to which nonlinear programming techniques could be applied to quantify the potential of super-ovulation, embryo transfer, sexed semen, in vitro fertilization and in vitro maturation of oocytes used singularly or in combination to improve genetically beef cattle growth and(or) reproductive efficiency. The function to be maximized adds genetic gain times the sale price of the additional product brought about by the genetic selection program, and any income change due to change from the normal replacement rate of females, and subtracts the additional costs of the breeding program over a random breeding program. All this is expressed on a per-calf-sold basis to arrive at the economic return of the breeding program per calf raised to market age. The rate of increase in inbreeding can be restricted as desired. It is assumed that a progeny testing procedure is practiced for the selection of sires. The power of nonlinear programming to find maximums of functions with many variables and to measure how sensitive the genetic and economic returns are to various success rates for the biotechnologies mentioned above is discussed.

Animals↗
PubMedDate not supplied

Embryonic stem cells and the bigger reprogenetic picture.

In this country, public policy conversations about reproductive and genetic technologies have been conducted separately. This makes it difficult for policy makers and the public to notice the extent to which reproductive and genetic technologies are converging, and thus the extent to which we are approaching the possibility of reprogenetically shaping our children. Embryonic stem cell research offers a superb opportunity to identify that convergence, and thus to begin considering the creation of a public institution that would be devoted to contemplating the bigger picture of reprogenetically shaping children.

Animals↗