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Transgenerational Effects (transgenerational + effects)
Selected AbstractsEcological selection maintains cytonuclear incompatibilities in hybridizing sunflowersECOLOGY LETTERS, Issue 10 2008Julianno B. M. Sambatti Abstract Despite the recent renaissance in studies of ecological speciation, the connection between ecological selection and the evolution of reproductive isolation remains tenuous. We tested whether habitat adaptation of cytoplasmic genomes contributes to the maintenance of reproductive barriers in hybridizing sunflower species, Helianthus annuus and Helianthus petiolaris. We transplanted genotypes of the parental species, reciprocal F1 hybrids and all eight possible backcross combinations of nuclear and cytoplasmic genomes into the contrasting xeric and mesic habitats of the parental species. Analysis of survivorship across two growing seasons revealed that the parental species' cytoplasms were strongly locally adapted and that cytonuclear interactions (CNIs) significantly affected the fitness and architecture of hybrid plants. A significant fraction of the CNIs have transgenerational effects, perhaps due to divergence in imprinting patterns. Our results suggest a common means by which ecological selection may contribute to speciation and have significant implications for the persistence of hybridizing species. [source] Assessing human germ-cell mutagenesis in the Postgenome Era: A celebration of the legacy of William Lawson (Bill) Russell,ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2007Andrew J. Wyrobek Abstract Birth defects, de novo genetic diseases, and chromosomal abnormality syndromes occur in ,5% of all live births, and affected children suffer from a broad range of lifelong health consequences. Despite the social and medical impact of these defects, and the 8 decades of research in animal systems that have identified numerous germ-cell mutagens, no human germ-cell mutagen has been confirmed to date. There is now a growing consensus that the inability to detect human germ-cell mutagens is due to technological limitations in the detection of random mutations rather than biological differences between animal and human susceptibility. A multidisciplinary workshop responding to this challenge convened at The Jackson Laboratory in Bar Harbor, Maine. The purpose of the workshop was to assess the applicability of an emerging repertoire of genomic technologies to studies of human germ-cell mutagenesis. Workshop participants recommended large-scale human germ-cell mutation studies be conducted using samples from donors with high-dose exposures, such as cancer survivors. Within this high-risk cohort, parents and children could be evaluated for heritable changes in (a) DNA sequence and chromosomal structure, (b) repeat sequences and minisatellites, and (c) global gene expression profiles and pathways. Participants also advocated the establishment of a bio-bank of human tissue samples from donors with well-characterized exposure, including medical and reproductive histories. This mutational resource could support large-scale, multiple-endpoint studies. Additional studies could involve the examination of transgenerational effects associated with changes in imprinting and methylation patterns, nucleotide repeats, and mitochondrial DNA mutations. The further development of animal models and the integration of these with human studies are necessary to provide molecular insights into the mechanisms of germ-cell mutations and to identify prevention strategies. Furthermore, scientific specialty groups should be convened to review and prioritize the evidence for germ-cell mutagenicity from common environmental, occupational, medical, and lifestyle exposures. Workshop attendees agreed on the need for a full-scale assault to address key fundamental questions in human germ-cell environmental mutagenesis. These include, but are not limited to, the following: Do human germ-cell mutagens exist? What are the risks to future generations? Are some parents at higher risk than others for acquiring and transmitting germ-cell mutations? Obtaining answers to these, and other critical questions, will require strong support from relevant funding agencies, in addition to the engagement of scientists outside the fields of genomics and germ-cell mutagenesis. Environ. Mol. Mutagen., 2007. Published 2007 Wiley-Liss, Inc. [source] Reproductive and transgenerational effects of methylmercury or Aroclor 1268 on Fundulus heteroclitusENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2001Mary Baker Matta Abstract This research determined the potential for methylmercury or Aroclor 1268 to disrupt reproduction and sexual differentiation in Fundulus heteroclitus. The research determined whether fish that are exposed to mercury or Aroclor 1268 survive and successfully reproduce; whether offspring of exposed fish hatch, survive, produce eggs, and fertilize them; and whether the secondgeneration offspring of exposed fish hatch and survive. Fundulus heteroclitus were exposed to mercury or Aroclor 1268 via contaminated food. Endpoints evaluated included survival, growth, fecundity, fertilization success, hatch success, larval survival, sex ratios, and the prevalence of gonadal abnormalities. In general, polychlorinated biphenyls were highly bioavailable and accumulated well through feeding. The only statistically significant effect observed as a result of treatment with Aroclor 1268 was an increase in growth in the offspring of exposed fish. Mercury was accumulated in a dose-dependent fashion via food exposures. Exposure to mercury in food increased mortality in male F. heteroclitus, which possibly occurred as a result of behavioral alterations. Increased mortality was observed at body burdens of 0.2 to 0.47 ,g/g. Offspring of F. heteroclitus fed mercury-contaminated food were less able to successfully reproduce, with reduced fertilization success observed at egg concentrations of 0.01 to 0.63 ,g/g, which corresponds with parent whole-body concentrations of 1.1 to 1.2 ,g/g. Offspring of exposed fish also had altered sex ratios, with treatment at moderate concentrations producing fewer females and treatment at the highest concentration producing more females than expected. Alterations in sex ratios were observed at concentrations of less than 0.01 ,g/g in eggs or between 0.44 and 1.1 ,g/g in parents. Offspring of mercury-exposed fish also had increased growth in moderate treatments, when egg concentrations were less than 0.02 ,g/g, or when parent whole bodies contained 0.2 to 0.47 ,g/g. In summary, exposure to mercury reduced male survival, reduced the ability of offspring to successfully reproduce, and altered sex ratios in offspring. Both direct effects on exposed fish and transgenerational effects were observed. [source] Elsewhere and Otherwise: Lévinasian Eros and Ethics in Le Clézio's La quarantaineORBIS LITERARUM, Issue 4 2001Karen D. Levy Beginning in the 1930s, Emmanuel Lévinas called into question the totalizing priorities of the Western metaphysical tradition and developed a dramatically original description of how subjectivity is constructed in the context of what he terms a face to face encounter with an absolute Other. This destabilizing experience is presented in terms of a summons that demands an ethical response in the form of unqualified moral responsibility for the well being of the Other, without any expectation of reciprocity. In a series of profoundly challenging works, Lévinas analyzes the different stages in the development of this relationship, expressed in masculine oriented terms, and he contrasts the nobility and generosity of ethics with the intimacy of eros and the welcome of the feminine in a protected domestic site. Lévinas insists on the impossibility of fusion and possession in both the ethical and the erotic relationships and seeks to disengage his discourse from essentialist, gender based interpretations. Nevertheless, he privileges terms associated with masculine subjects and likewise seems to endorse stereotypical interpretations of the feminine as fragile and frail, inviting either pity or tenderness. The fact that eros is based on an equivocation between need and the desire for something absolutely Other, which does not depend on any lack, prevents it from attaining the same stature as ethics. And by leaving the feminine out of his discussion of ethics, Lévinas at least downplays the possibility for feminine subjects to respond to the summons of the face to face encounter and accept the risk of living other than in the metaphysical dwelling of Being. The questions raised in Lévinas' works concerning eros, ethics, and the feminine assume different configurations and lead elsewhere when explored in proximity to J.M.G. Le Clézio's emblematic saga La quarantaine. Similar in many ways to Lévinas' philosophical trajectory, Le Clézio's literary undertaking details the disjointed stages of a journey from the self-contained solitude of Being to an exposed elsewhere in what Lévinas calls the "au-delà de l'être." The multi-layered text of La quarantaine fictionalizes the crisis that caused Le Clézio's great-uncle to be erased from family history and depicts the transgenerational effects of that disappearance. The originality of Le Clézio's work stems from the double inscription of the alterity of both eros and ethics in an Other who is gendered female. His text explores the process of rupture and exposure that Lévinas valorizes, but it does so in a way that reveals how a female subject, who both welcomes discreetly and imposes herself indiscreetly, challenges what Lévinas calls the "égoïté tragique" of the other protagonists. Le Clézio's arrestingly beautiful prose serves as a kind of textual face that expresses concretely the complexity of Lévinas' preoccupations and summons us as readers to exceed our capacities and live otherwise. [source] Sex-specific transgenerational effects of early developmental conditions in a passerineBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2007CARLOS ALONSO-ALVAREZ Most studies dealing with the trade-off between offspring number and quality have overlooked the long-term consequences for the progeny. High investment in offspring number usually results in an increased competition among nest mates. The deterioration of the early developmental conditions, due to this increased competition, can impair individual quality over the long term, and subsequently affect survival and lifetime fecundity. Moreover, the consequences of the allocation rule to offspring number vs. quality can extend across generations and give raise to grandparental effects. These transgenerational trade-offs have been explored rarely. In the present study, we manipulated the breeding effort of captive zebra finches (Taeniopygia guttata) by offering them enlarged or reduced broods. Offspring reared under these conditions were allowed to breed freely in an outdoor aviary, during their entire lifespan. Second-generation fledglings whose mother was raised in enlarged broods were in lower body condition than offspring whose mother was raised in reduced broods. However, second-generation fledglings were not affected by the brood size experienced by the father. These results show that the solution of parental dilemma, whether producing a small number of high quality offspring or a large number of poor quality descendants, must take into account the long-term transgenerational effects acting on grandchildren. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 469,474. [source] | ||||||||||