Genetics: reproduction rights.
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Bioethics↗
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Results for “Genetics and Reproduction”
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[Symposium on intrauterine genetics. Reproductive failures in relation to chromosome abnormalities].
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Abortion, Spontaneous↗
Genetic reproductive loss in the developing embryo/fetus.
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Animals↗
Women as body parts in the era of reproductive and genetic engineering.
Reproductive and genetic engineering are presented by their promoters as miracle cures for people with infertility problems or who are at genetic risk in having their desired healthy child. Focusing on the test-tube baby method (in vitro fertilization), in this article I investigate the medical reality of these technologies and their impact on women's lives as individuals and as members of a social group, women. Specifically, I discuss these developments in a global context and suggest that, in connection with fertility-control methods, they could be used as the ultimate means of population control. I contend that reproductive and genetic engineering dismember, fragment, and dissect women into their body parts and that, in the interests of women with a right to bodily integrity and dignity, they need to be stopped.
Female↗
Genetic factors in reproduction and their evolutionary significance.
PROBLEM: The reproductive process is a major driving force in human evolution. An evolutionary perspective was brought to bear on some aspects of reproduction and its aberrations, and, conversely, some of the insights of modern reproductive genetics were used to investigate problems in evolution. METHOD: The data used were obtained from the literature in evolution, anthropology, archeology, linguistics, and genetics. RESULTS: The evolutionary line leading to modern humans diverged from that leading to the chimpanzees approximately 5-7 million years ago (Mya). Archaic Homo sapiens emerged ca. 0.3 Mya, and modern Homo sapiens and the development of language ca. 0.1 Mya; thus, modern humans occupy approximately 2% of the evolutionary history of the hominid line. During all of this time, the ancestors of modern humans were migratory hunter-gatherers. It was only during the Neolithic transition ca. 0.01 Mya (approximately 0.2% of hominid evolutionary history) that agriculture was developed, and with it a settled lifestyle that allowed a more stable existence and the development of a different reproductive pattern. Various estimates indicate that the human population increased from 0.05 million at the time of the emergence of modern Homo sapiens to 6,000 million at the present time (120,000-fold increase). CONCLUSIONS: These evolutionary considerations were used to explore three areas: (1) the extinction of the Neanderthals, who coexisted for ca. 65,000 years with modern humans; (2) the relatively low and stable rate of human conceptions (20-35% of ova fertilized naturally or fertilized in vitro); and (3) the long postnatal period required for the full maturation of the immune response. From these considerations, a broad view of the human reproductive process was obtained that may provide some insight into the rationale for the development of effective reproductive technologies.
Animals↗
Can alcohol retain the reproductive and genetic potential of sperm nuclei? Chromosome analysis of mouse spermatozoa stored in alcohol.
Alcohol is known to preserve genomic DNA and the primary structure of sperm protamines. To determine whether alcohol can retain the genetic and reproductive potential of mammalian sperm nuclei, mature mouse spermatozoa were stored in 70% ethanol or propanol for up to 2 months before injection into oocytes. Live offspring were obtained after injection of spermatozoa stored in 70% ethanol for 1 day at -20 degrees C. About 20% of the spermatozoa stored under this condition had normal chromosomes. The remaining 80% of spermatozoa and all the spermatozoa stored in 70% ethanol for 2 months had structurally aberrant chromosomes, and none could support the development of normal embryos. High concentrations of alcohol do not alter the primary structure of either DNA or small-molecular-weight protamines. However, alcohol may modify protamine-protamine or protamine-DNA interactions in a manner that results in the induction of DNA strand breaks during sperm chromatin decondensation within the oocyte. The limited success in obtaining normal offspring with ethanol-stored spermatozoa is encouraging. It may be possible to overcome these problems and develop a simple method for preserving mammalian spermatozoa without freezing.
Animals↗
Comparison of Henderson's Method I and restricted maximum likelihood estimation of genetic parameters of reproductive traits.
Genetic parameters of simulated reproductive traits were estimated with Henderson's Method I or restricted maximum likelihood (REML). Each of the 25 samples consisted of 2,667 birds from 50 sires. When reproductive traits were measured on all birds, the means of both sets of estimates were equal to the true value; however, precision was higher with REML. When they were only measured on the 60 (20%) heaviest birds, Henderson's Method I was severely biased by selection (up to 40% for estimates of heritability of reproductive traits and up to 45% for estimates of genetic correlation between reproductive traits and body weight). This bias, as well as the variance of estimates, increased with selection rate and absolute value of genetic correlation between body weight and reproductive traits (or another criterion of selection). Conversely, REML was not biased by selection. It should therefore be preferred when sequential selection occurs.
Analysis of Variance↗
Genome mapping in ruminants and map locations for genes influencing reproduction.
Genetic maps provide a critical link between genes and phenotypes and are essential tools in the search for the genetic basis of variation in reproductive traits. Genes coding for hormones, growth factors, receptors, binding proteins, transcription factors and enzymes that influence the development and function of the reproductive axis have been assigned to genetic maps of ruminants and locations can be found in the respective genome databases. In addition, comparative information on gene structure and map location will help define the functions of essential genes. Gene locations from other species can be used because of extensive comparative links among mammalian gene maps. Large-scale projects to sequence genes and the ability to map these genes in parallel in radiation hybrid panels of different species will greatly improve the maps and our ability to translate between them. Cloning the genes responsible for genetic differences in fertility and fecundity in ruminants is likely to provide valuable clues to understanding ovarian function and germ cell development.
Animals↗
Assisted reproductive technologies: genetic and nursing implications.
The convergence of the fields of clinical genetics and assisted reproductive technologies is providing couples at risk for transmitting a genetic disorder to their children with new reproductive alternatives. The ability to test the preimplantation embryo for genetic anomalies, sort for X- and Y-bearing sperm, and improve genetic screening of gamete donors and couples at risk for a genetic disorder, are examples of these alternatives. The scope of nursing practice will be affected by the integration of these technologies into the health care offered to consumers. Opportunities also will exist for nurses to assist in the redefinition of health and illness that will be the serendipitous outcome of these scientific advances.
Genetic Testing↗
Sex and death in the mouse: genetically delayed reproduction and senescence.
A mammalian model of genetically postponed aging would be an important tool to test not only different mechanisms of aging but also the predictive value of various biomarkers of the aging process. Under conventional conditions, the historical strains of the laboratory mouse produce their first litter between 9 and 13 weeks of age and have a median time of death in their 2nd year. Our POSCH-2 strain, which was derived from wild-caught Mus musculus domesticus, produces its first litter in the current breeding generations at approximately 47 weeks of age and continues to breed throughout its 2nd and into its 3rd year of life. The aging curve of POSCH-2 has not yet been determined for economic reasons. Late onset of breeding is a characteristic of both females and males, but sexual maturity is more reliably assessed in females. The later breeding phenotype of POSCH-2 is genetically recessive to early breeding of the C57BL/6J historical laboratory strain and, since POSCH-2 females can be induced to ovulate at 8 weeks of age (but pregnancy does not result), the signal rather than the ovarian receptor to ovulate may be delayed. The genetically delayed reproduction and potentially longer life of the POSCH-2 strain appears to be a new trait in the mouse. The strain may be a useful mammalian model for aging studies and for the evaluation of antagonistic pleiotropy as a genetic model for the evolution of aging.
Aging↗
Advances in the genetics of reproductive isolation in Drosophila.
Speciation genetics is defined as the study of genetic events and processes that differentiate the probabilities that genetic material from individual members of a population will co-occur in individuals of some future generation. It follows that phenotypic attributes that contribute to this differentiation of probabilities (e.g., mating preferences, sterility, or infertility of individuals from certain types of matings) constitute the phenotype of speciation, and genetic loci that may affect these phenotypic attributes can be considered as speciation genes. The literature on genetic differences between hybridizable species of Drosophila that are responsible for morphological differences, mating preferences, hybrid inviability, and hybrid sterility are reviewed with special reference to the species pair D. mojavensis - D. arizonensis. The case for the involvement of karyotypic changes in speciation in rodents is briefly discussed. It is concluded that no major advance has been made in the speciation genetics of Drosophila since Dobzhansky initiated the field 40 years ago. Yet, the identification of several gene loci that cause hybrid inviability or sterility may open the way to the understanding of reproductive isolation at the molecular level. It is not clear whether this approach will lead to general molecular mechanisms underlying the speciation process.
Animals↗
Genetics and reproduction in fish culture.
Fish genetics has made major strides during the past 20 yr due both to improvements in the ability of fish culturists to manage reproduction and to deliberate experimentation and application. The general finding has been that the quantitative genetics of fish differ little from those of other animals and that the applications of animal improvement techniques are similar for fish and other animals. In addition, a number of novel techniques, such as ploidy manipulation and sex reversal, are relatively easy to achieve with a number of fish species. As a result, some very specialized approaches to research have been possible, and applications to fish production seem to be limited only to the imagination of the breeder. However, only limited application has occurred over a major portion of the industry, and genetic improvement of stocks has been achieved in very few instances. The reason for this apparent dichotomy between opportunity and reality seems to be related to the industry's lack of emphasis on genetic improvement.
Agriculture↗
Wnt genes and endocrine disruption of the female reproductive tract: a genetic approach.
Reproductive tract development and function is regulated by circulating steroid hormones. In the mammalian female reproductive tract, estrogenic compounds direct many aspects of cytodifferentiation including uterine gland formation, smooth muscle morphology, and epithelial differentiation. While it is clear that these hormones act through their cognate nuclear receptors, it is less clear what signaling events follow hormonal stimulation that govern cytodifferentiation. Recent advances in molecular embryology and cancer cell biology have identified the Wnt family of secreted signaling molecules. Discussed here are recent advances that point to a definitive role during uterine development and adult function for one member of the Wnt gene family, Wnt-7a. In addition, recent data is reviewed that implicates Wnt-7a deregulation in response to pre-natal exposure to the synthetic estrogenic compound, DES. These advances point to an important role for the Wnt gene family in various reproductive tract pathologies including cancer.
Animals↗
Genetics of reproduction in primiparous Holsteins.
Effects of genetics and relationships between yield and days from parturition to first service, first service conception rate, number of services, and a reproductive performance code based on several reproductive components were investigated in primiparous Holsteins. Recorded breedings and DHI production records were from 3393 daughters of 174 bulls in six experimental herds. Subsets included progeny of 78 sires, with greater than or equal to 5 daughters calving in April through July (n = 817) and August through March (n = 1162). Daughter-dam regressions (n = 2593 pairs) and paternal half-sibs were used to estimate heritabilities of fertility traits and associations between yield and reproduction. Results showed increased FCM was associated with lowered fertility. For paternal half-sibs, the greatest antagonism was between conception rates and FCM (rG = -.65 +/- .10). Daughter-dam regressions estimated a favorable genetic correlation of .43 +/- .32 between conception rates and yield. Heritabilities were highest for April through July calvings and ranged from .08 +/- .10 for first service conception to .24 +/- .12 for reproductive code. Correlations between sire least squares constants from warmer and cooler calving seasons were lower than heritabilities of traits would suggest.
Animals↗
Spinocerebellar ataxia in a large kindred: age at onset, reproduction, and genetic linkage studies.
We studied a large kindred with autosomal dominant spinocerebellar ataxia (SCA) to assess reproductive performance, the impact of genetic counseling, and linkage relationships of the SCA locus. Reproduction was not lower in those with SCA than in unaffected sibs or first cousins. Genetic counseling reduced reproduction during the risk period for development of SCA. Given autosomal dominant transmission of a single gene, we found strong evidence that the locus for SCA in this kindred is linked to the HLA loci.
Adolescent↗
Interactions between genetic and reproductive factors in breast cancer risk in a French family sample.
Considerable progress has been made in the characterization of the genetic component of breast cancer (BC). However, BC still remains a complex disease involving a genetic component and many other risk factors essentially linked to reproductive-life factors. To search for interactions between genetic and reproductive-life factors in the etiology of BC, a systematic family study was performed in two French hospitals from December 1987 to January 1990 and led to recruitment of 288 families, the IGRC data ("IGRC" refers to the Institut Gustave Roussy and Institut Curie, where the data were obtained). Detailed information on reproductive factors was recorded for probands and female first-degree relatives. Segregation analysis of BC was conducted by taking into account a variable age at onset of disease, by use of the class D regressive logistic model, as implemented in the REGRESS computer program. Segregation analyses of BC in IGRC data showed evidence for the segregation of a dominant gene and additional sister-sister dependence, both when reproductive factors were ignored and when they were included. A significant interaction was detected between the dominant gene and age when reproductive factors were taken into account. Among the reproductive factors included in segregation analysis, parity was found to interact with the dominant-gene effect, and there was an indication of an interaction, albeit not significant, between the dominant gene and age at menarche. Whereas the usual protective effect conferred on breast-cancer risk by high parity remained in nonsusceptible women, it disappeared in susceptible women. The increased BC risk associated with a late age at menarche was higher in susceptible women than in nonsusceptible women. Interactions between inherited predisposition to BC and reproductive factors were detected here for the first time by segregation analysis. It would be of major interest to confirm these results by family studies in other populations.
Abortion, Spontaneous↗
Are both genetic and reproductive associations with rheumatoid arthritis linked to prolactin?
The risk of rheumatoid arthritis (RA) seems to be associated with reduced fecundity and with breastfeeding; these apparently contradictory risk factors can be explained by their association with high prolactin concentrations. The only consistent genetic association with RA is for genes encoded in the HLA complex, particularly HLA DR4. We have identified some data indicating that the effects of breastfeeding and nulliparity are modified by HLA DR4 status, suggesting an interaction between genetic and reproductive risk factors in the aetiology of RA. The prolactin gene is in close proximity to the HLA region on the short arm of chromosome six. We therefore propose the hypothesis that the associations between DR4 and reproductive risk factors in RA are due to linkage disequilibrium between DR4 and an abnormally regulated prolactin gene polymorphism.
Arthritis, Rheumatoid↗
The genetics of reproductive isolation in the Drosophila simulans clade: X vs. autosomal effects and male vs. female effects.
A strong effect of homozygous autosomal regions on reproductive isolation was found for crosses between the species in the Drosophila simulans clade. Second chromosome regions were introgressed from D. mauritiana and D. sechellia into D. simulans and tested for their homozygous effects on hybrid male and hybrid female sterility and inviability. Most introgressions are fertile as heterozygotes, yet produce sterile male offspring when made homozygous. The density of homozygous autosomal factors contributing to hybrid male sterility is comparable to the density of X chromosome factors for this level of resolution. Female sterility was also revealed, yet the disparity between male and female levels of sterility was great, with male sterility being up to 23 times greater than female sterility. Complete hybrid inviability was also associated with some regions of the second chromosome, yet there were no strong sex differences. In conclusion, we find no evidence to support a strong X chromosome bias in the evolution of hybrid sterility or inviability but do find a very strong sex bias in the evolution of hybrid sterility. In light of these findings, we reevaluate the current models proposed to explain the genetic pattern of reproductive isolation.
Alleles↗