Mechanism of Translational Control by the Fragile X Mental Retardation Protein and Creation of the FMRP CTAG Mouse

The Fragile X Mental Retardation Protein (FMRP) is a neuronal RNA-binding protein that is predominantly associated with polyribosomes. Loss of FMRP results in Fragile X Syndrome, characterized by mental retardation, autism and epilepsy. FMRP was recently found to be associated with a specific set of mRNAs with key roles in neuronal function and to physically interact with targeted mRNAs along their entire coding sequences (Darnell 2011). Here, we find that FMRP inhibits translation on these target transcripts by stalling ribosomes, both in vivo and in rabbit reticulocyte lysate programmed with endogenous brain polyribosomes. In these systems, loss of FMRP function resulted in increased ribosome runoff after treatment with puromycin, a drug that acts specifically on translocating ribosomes. In addition to genetic loss-of-function models, FMRPdependent relief of ribosome stalling could be induced by acute biochemical removal of FMRP from polysomes, indicating reversibility of stalling. FMRP was also directly visualized on stalled polysomes by immunoelectron microscopy. Together, these results suggest a model in which FMRP actively regulates translation of target mRNAs by stalling ribosomes. To further advance our understanding of FMRP function, we have created the FMRP cTAG mouse, a knock-in model in which FMRP can be conditionally tagged with AcGFP in a Cre-dependent manner while maintaining wt FMRP expression in all Cre-negative cells. The cTAG mouse will be a valuable tool in the study of cell type-specific FMRP function

The role of mental models in citizen science

An increasing number of citizen science projects involve citizens on levels of participation that go beyond data collection and entail the co-creation of research questions and methods as well as the project pathway. The success of such projects depends on the establishment of shared knowledge, a task that can be especially challenging in citizen science that focuses on complex societal issues and the so-called wicked problems. We suggest that this challenge can be addressed through a deeper engagement with research on mental models—cognitive representations of external reality that largely define human thinking, decision-making and behaviour. Moreover, particular emphasis should be placed on the effective co-creation of shared mental models, whereby design thinking could provide valuable methodologies and tools. The objective of the workshop “Mental Models in Citizen Science” was to dive into mental model theory and design thinking toolbox and explore their potential for citizen science. This paper provides an overview of the workshop activities and insights and proposes a research agenda shaped around mental models and their role in citizen science

Biological Control of Fenusa pusilla (Hymenoptera: Tenthredinidae) in the Northeastern United States: A Thirty-four Year Perspective on Efficacy

Parasitoid releases against the birch leafminer Fenusa pusilla (Lepeletier) (Hymenoptera: Tenthredinidae) in eastern North America began in 1974, with releases in eastern Canada, followed by others in the Middle Atlantic States and New England. Of 4 parasitoids released, only 1, the ichneumonid Lathrolestes nigricollis (Thompson), established and spread widely. Studies of its preliminary impacts were made in several locations in the 1980s and 1990s, but full impact of the parasitoid on host density was not yet achieved in that period. Here we report results of surveys in 7 states (MA, CT, RI, NY, PA, NJ, DE) in 2007 documenting the current birch leaf miner levels (as % of leaves mined in spring) and parasitism. Survey results show that the pest has declined dramatically to barely detectable levels in 5 states (MA, CT, RI, NY, PA) but that in southern NJ, the pest remains abundant (ca 50% leaves mined) despite significant parasitism levels. Survey results, in context with previous evaluations made when populations were still declining, show that the project has been completely successful in much of the northeastern USA, but that there is a southern limit to efficacy in mid-New Jersey. Possible reasons for lack of control in this area, in contrast to high levels of control elsewhere, are discussed

In utero exposure to cigarette smoke dysregulates human fetal ovarian developmental signalling

STUDY QUESTION How does maternal cigarette smoking disturb development of the human fetal ovary?<p></p> SUMMARY ANSWER Maternal smoking increases fetal estrogen titres and dysregulates several developmental processes in the fetal ovary.<p></p> WHAT IS KNOWN ALREADY Exposure to maternal cigarette smoking during gestation reduces human fetal ovarian cell numbers, germ cell proliferation and subsequent adult fecundity.<p></p> STUDY DESIGN, SIZE, DURATION The effects of maternal cigarette smoking on the second trimester human fetal ovary, fetal endocrine signalling and fetal chemical burden were studied. A total of 105 fetuses were studied, 56 from mothers who smoked during pregnancy and 49 from those who did not.<p></p> PARTICIPANTS/MATERIALS, SETTING METHODS Ovary, liver and plasma samples were collected from electively terminated, normally progressing, second trimester human fetuses. Circulating fetal hormones, levels of 73 fetal ovarian transcripts, protein localization, density of oocytes/primordial follicles and levels of 16 polycyclic aromatic hydrocarbons (PAHs) in the fetal liver were determined.<p></p> MAIN RESULTS AND THE ROLE OF CHANCE Circulating fetal estrogen levels were very high and were increased by maternal smoking (ANOVA, P = 0.055–0.004 versus control). Smoke exposure also dysregulated (two-way ANOVA, smoking versus gestation weeks interaction, P = 0.046–0.023) four fetal ovarian genes (cytochrome P450 scc [CYP11A1], NOBOX oogenesis homeobox [NOBOX], activator of apoptosis harakiri [HRK], nuclear receptor subfamily 2, group E, member 1 [NR2E1]), shifted the ovarian Inhibin βA/inhibin α ratio (NHBA/INHA) transcript ratio in favour of activin (ANOVA, P = 0.049 versus control) and reduced the proportion of dominant-negative estrogen receptor 2 (ERβ: ESR2) isoforms in half the exposed fetuses. PAHs, ligands for the aryl hydrocarbon receptor (AHR), were increased nearly 6-fold by maternal smoking (ANOVA, P = 0.011 versus control). A fifth transcript, COUP transcription factor 1 (nuclear receptor subfamily 2, group F, member 1: NR2F1, which contains multiple AHR-binding sites), was both significantly increased (ANOVA, P = 0.026 versus control) and dysregulated by (two-way ANOVA, smoking versus gestation weeks interaction, P = 0.021) maternal smoking. NR2F1 is associated with repression of FSHR expression and smoke-exposed ovaries failed to show the normal increase in FSHR expression during the second trimester. There was a significantly higher number of DEAD (Asp-Glu-Ala-Asp) box polypeptide 4 (DDX4) VASA-positive (ANOVA, P = 0.016 versus control), but not POU domain, class 1, transcription factor 1 (POU5F1) OCT3/4-positive, oocytes in smoke-exposed fetuses and this matched with a significantly higher number of primordial follicles (ANOVA, P = 0.024 versus control).<p></p> LIMITATIONS, REASONS FOR CAUTION The effects of maternal smoking on establishment of the maximum fetal primordial follicle pool cannot be reliably studied in our population since the process is not completed until 28 weeks of gestation and normal fetuses older than 21 weeks of gestation are not available for study. Our data suggest that some fetal ovaries are affected by smoke exposure while others are not, indicating that additional studies, with larger numbers, may show more significant effects.<p></p> WIDER IMPLICATIONS OF THE FINDINGS Fetal exposure to chemicals in cigarette smoke is known to lead to reduced fecundity in women. Our study suggests, for the first time, that this occurs via mechanisms involving activation of AHR, disruption of inhibin/activin and estrogen signalling, increased exposure to estrogen and dysregulation of multiple molecular pathways in the exposed human fetal ovary. Our data also suggest that alterations in the ESR2 positive and dominant negative isoforms may be associated with reduced sensitivity of some fetuses to increased estrogens and maternal smoking