553 research outputs found
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Troubled sleep: Night waking, breastfeeding and parentâoffspring conflict
Disrupted sleep is probably the most common complaint of parents with a new baby. Night waking increases in the second half of the first year of infant life and is more pronounced for breastfed infants. Sleep-related phenotypes of infants with Prader-Willi and Angelman syndromes suggest that imprinted genes of paternal origin promote greater wakefulness whereas imprinted genes of maternal origin favor more consolidated sleep. All these observations are consistent with a hypothesis that waking at night to suckle is an adaptation of infants to extend their mothersâ lactational amenorrhea, thus delaying the birth of a younger sib and enhancing infant survival
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Frugal fat or munificent muscle: genomic imprinting and metabolism
Variation in body composition is a popular obsession. The culturally âidealâ body type is light on fat and heavy on muscle but the human population is collectively laying on fat. A new study finds antagonistic effects of two imprinted genes, Grb10 and Dlk1, on body composition in mice. These findings pose the question whether there is an evolutionary conflict between genes of maternal and paternal origin over the optimal proportions of body fat and lean muscle mass. See research article: http://www.biomedcentral.com/1741-7007/12/9
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Interbirth intervals: Intrafamilial, intragenomic and intrasomatic conflict
Background and objectives: Interbirth intervals (IBIs) mediate a trade-off between child number and child survival. Life history theory predicts that the evolutionarily optimal IBI differs for different individuals whose fitness is affected by how closely a mother spaces her children. The objective of the article is to clarify these conflicts and explore their implications for public health. Methodology: Simple models of inclusive fitness and kin conflict address the evolution of human birth-spacing. Results:: Genes of infants generally favor longer intervals than genes of mothers, and infant genes of paternal origin generally favor longer IBIs than genes of maternal origin. Conclusions and implications: The colonization of maternal bodies by offspring cells (fetal microchimerism) raises the possibility that cells of older offspring could extend IBIs by interfering with the implantation of subsequent embryos
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The Epidemiology of Epigenetics
Organismic and Evolutionary Biolog
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Sarah and Constant Broyer, Pharmacist and Physician, of Carlton
Constant Broyer (1833â1911) trained as a herbalist in Victoria during the 1850s and practised as a medical botanist in Carlton in the 1860s. He obtained medical degrees from the Eclectic Medical College of Cincinnati (1875) and Harvard University (1879). He is perhaps the first Australian to have studied at Harvard. He was twice found guilty of manslaughter by a coronerâs jury in 1874 and 1896. Both cases were much publicised but Broyer was not prosecuted on either charge. His wife, Sarah Broyer (1829â1877), ran the family pharmacy during her husbandâs absence in America in the 1870s. She was the first woman to apply for registration as a pharmacist in Victoria in 1877 under the new Pharmacy Act and was represented in her negotiations before the Pharmacy Board by a young barrister, Alfred Deakin. This article traces the chronology and major events shaping the personal, professional and public lives of Constant and Sarah Broyer (and their extended family) from the mid-nineteenth century to the 1940s.Organismic and Evolutionary Biolog
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Kinship Asymmetries and the Divided Self
Imprinted genes are predicted to affect interactions among relatives. Therefore, variant alleles at imprinted loci are promising candidates for playing a causal role in disorders of social behavior. The effects of imprinted genes evolved in the context of patterns of asymmetric relatedness that existed within social groups of our ancestors.Organismic and Evolutionary Biolog
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Games in Tetrads: Segregation, Recombination, and Meiotic Drive
The two alleles at a heterozygous locus segregate during meiosis, sometimes at meiosis I and sometimes at meiosis II. The timing of segregation is determined by the pattern of crossingâover between a locus and its attached centromeres. Genes near centromeres can exploit this process by driving against spores from which the genes separated at meiosis I. Other genes, located distal to centromeres, can benefit from driving against spores from which they separated at meiosis II. Asymmetric female meiosis is particularly susceptible to such forms of drive. Selection on modifiers of recombination favors changes in the location of chiasmata that increase the proportion of tetrads of high average fitness by changing the timing of segregation. Such changes increase the frequency of driving alleles. This source of selection on recombination does not depend on effects on linkage disequilibrium. Recombinational responses to meiotic drive may contribute to sex differences in overall recombination and sex differences in the localization of chiasmata.Organismic and Evolutionary Biolog
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The Strategic Gene
Gene-selectionists define fundamental terms in non-standard ways. Genes are determinants of difference. Phenotypes are defined as a geneâs effects relative to some alternative whereas the environment is defined as all parts of the world that are shared by the alternatives being compared. Environments choose among phenotypes and thereby choose among genes. By this process, successful gene sequences become stores of information about what works in the environment. The strategic gene is defined as a set of gene tokens that combines âactorâ tokens responsible for an effect with ârecipientâ tokens whose replication is thereby enhanced. This set of tokens can extend across the boundaries of individual organisms, or other levels of selection, as these are traditionally defined.Organismic and Evolutionary Biolog
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Retroviruses and the Placenta
Retroviruses are often expressed in the placenta. Placental expression probably evolved to facilitate retroviral transmission from mother to offspring and from offspring to mother. In the process, the placenta became a site where retroviral genes were âdomesticatedâ to serve adaptive functions in the host, including the manipulation of maternal physiology for the benefit of the fetus. The evolutionary interplay between retroviruses and host defenses may have contributed to the remarkable diversity of form among mammalian placentas and to mechanisms of genomic imprinting.Organismic and Evolutionary Biolog
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