Mouse Gestation Length Is Genetically Determined

Background: Preterm birth is an enormous public health problem, affecting over 12 % of live births and costing over $26 billion in the United States alone. The causes are complex, but twin studies support the role of genetics in determining gestation length. Despite widespread use of the mouse in studies of the genetics of preterm birth, there have been few studies that actually address the precise natural gestation length of the mouse, and to what degree the timing of labor and birth is genetically determined. Methodology/Principal Findings: To further develop the mouse as a genetic model of preterm birth, we developed a highthroughput monitoring system and measured the gestation length in 15 inbred strains. Our results show an unexpectedly wide variation in overall gestation length between strains that approaches two full days, while intra-strain variation is quite low. Although litter size shows a strong inverse correlation with gestation length, genetic difference alone accounts for a significant portion of the variation. In addition, ovarian transplant experiments support a primary role of maternal genetics in the determination of gestation length. Preliminary analysis of gestation length in the C57BL/6J-Chr # A/J /NaJ chromosome substitution strain (B.A CSS) panel suggests complex genetic control of gestation length. Conclusions/Significance: Together, these data support the role of genetics in regulating gestation length and present th

TMEM161B modulates radial glial scaffolding in neocortical development.

TMEM161B encodes an evolutionarily conserved widely expressed novel 8-pass trans- membrane protein of unknown function in human. Here we identify TMEM161B homozygous hypomorphic missense variants in our recessive polymicrogyria (PMG) cohort. Patients carrying TMEM161B mutations exhibit striking neocortical PMG and intellectual disability. Tmem161b knockout mice fail to develop midline hem- ispheric cleavage, whereas knock-in of patient mutations and patient-derived brain organoids show defects in apical cell polarity and radial glial scaffolding. We found that TMEM161B modulates actin filopodia, functioning upstream of the Rho-GTPase CDC42. Our data link TMEM161B with human PMG, likely regulating radial glia apical polarity during neocortical development

Crowdsourcing hypothesis tests: Making transparent how design choices shape research results

To what extent are research results influenced by subjective decisions that scientists make as they design studies? Fifteen research teams independently designed studies to answer fiveoriginal research questions related to moral judgments, negotiations, and implicit cognition. Participants from two separate large samples (total N > 15,000) were then randomly assigned to complete one version of each study. Effect sizes varied dramatically across different sets of materials designed to test the same hypothesis: materials from different teams renderedstatistically significant effects in opposite directions for four out of five hypotheses, with the narrowest range in estimates being d = -0.37 to +0.26. Meta-analysis and a Bayesian perspective on the results revealed overall support for two hypotheses, and a lack of support for three hypotheses. Overall, practically none of the variability in effect sizes was attributable to the skill of the research team in designing materials, while considerable variability was attributable to the hypothesis being tested. In a forecasting survey, predictions of other scientists were significantly correlated with study results, both across and within hypotheses. Crowdsourced testing of research hypotheses helps reveal the true consistency of empirical support for a scientific claim.</div

A novel allele of Alx4 results in reduced Fgf10 expression and failure of eyelid fusion in mice.

Normal fusion of developing eyelids requires coordination of inductive signals from the eyelid mesenchyme with migration of the periderm cell layer and constriction of the eyelids across the eye. Failure of this process results in an eyelids open at birth (EOB) phenotype in mice. We have identified a novel spontaneous allele of Alx4 that displays EOB, in addition to polydactyly and cranial malformations. Alx4 is expressed in the eyelid mesenchyme prior to and during eyelid fusion in a domain overlapping the expression of genes that also play a role in normal eyelid development. We show that Alx4 mutant mice have reduced expression of Fgf10, a key factor expressed in the mesenchyme that is required for initiation of eyelid fusion by the periderm. This is accompanied by a reduced number of periderm cells expressing phosphorylated c-Jun, consistent with the incomplete ablation of Fgf10 expression. Together, these data demonstrate that eyelid fusion in mice requires the expression of Alx4, accompanied by the loss of normal expression of essential components of the eyelid fusion pathway. Mamm Genome 2015 Apr; 26(3-4):173-8

Supporting conditional mouse mutagenesis with a comprehensive cre characterization resource.

Full realization of the value of the loxP-flanked alleles generated by the International Knockout Mouse Consortium will require a large set of well-characterized cre-driver lines. However, many cre driver lines display excision activity beyond the intended tissue or cell type, and these data are frequently unavailable to the potential user. Here we describe a high-throughput pipeline to extend characterization of cre driver lines to document excision activity in a wide range of tissues at multiple time points and disseminate these data to the scientific community. Our results show that the majority of cre strains exhibit some degree of unreported recombinase activity. In addition, we observe frequent mosaicism, inconsistent activity and parent-of-origin effects. Together, these results highlight the importance of deep characterization of cre strains, and provide the scientific community with a critical resource for cre strain information

Complex, polygenic regulation of gestation length is revealed by the B.A CSS panel.

<p>(A) Mean gestation time in total hours for each of 20 CSS. The total number of pregnancies monitored is indicated for each strain and data are presented as the mean +/− S.E.M. (B) Graphical representation of individual CSS with significantly different GLs independent of all other factors. Strains that are not associated by a letter are significantly different from each other (p<0.05).</p

Data summary from individual strain measurements.

<p>Total litter size includes all (live and dead) pups identified. Weight per live pup is the average of all surviving pups for each individual strain. Dead pups were often found desiccated and partially cannibalized and are thus excluded. Survival rate is the percentage of total pups identified that survived until at least postnatal day 3. Maternal weight was measured and recorded following the identification of a copulation plug and at E14.5 to calculate weight gain. At this time point, females were housed in front of the cameras and not disturbed until a birth was recorded. Pregnancy load is the maternal weight gained as a percentage of initial weight following a successful mating.</p

Gestation length is primarily dependent upon maternal genotype.

<p>(A) Gestation length presented in hours of C57BL/6J, A/J, B6.CB17-<i>Prkdc^scid</i>/SzJ (B6-<i>scid</i>), and B6-scid with transplanted A/J ovaries (AJ-ov-B6-<i>scid</i>). In order to directly compare the effect of pure B6 and A/J pups in a B6 maternal background, B6-<i>scid</i> mice were sham manipulated and mated to B6-scid males, while AJ-ov-B6-<i>scid</i> females were mated to A/J males following recovery from ovary transplant (see materials and methods for details). (B) Graphical representation of strains with significantly different GLs independent of all other factors. Strains that are not associated by a letter are significantly different from each other (p<0.05), demonstrating that B6 females show no statistical difference in gestation time, regardless of the genotype of the pups.</p

Highly significant differences in gestation length among inbred mouse strains.

<p>(A) Gestational length presented in total hours, measured from the midpoint of the dark cycle prior to the appearance of a copulation plug to the recorded appearance of the first pup. The total number of pregnancies monitored is indicated for each strain and data are presented as the mean +/− S.E.M. A detailed description of the animal husbandry and measurement procedures is provided in the supplementary methods (6). (B) Live litter size (number of pups), maternal weight gain (at E14.5) and maternal load (% weight gain) for each of the 15 inbred strains measured in (A). Complete data are presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0012418#pone-0012418-t001" target="_blank">Table 1</a>. (C) Effects test (analysis of covariance) demonstrating significant differences in GL among inbred strains independent of the effect of total litter size and maternal load. Litter size is also significantly different among strains and is strongly correlated with GL. (D) Graphical representation of strains with significantly different GLs independent of all other factors. Strains that are not associated by a letter are significantly different from each other (p<0.05).</p

TMEM161B modulates radial glial scaffolding in neocortical development

TMEM161B encodes an evolutionarily conserved widely expressed novel 8-pass transmembrane protein of unknown function in human. Here we identify TMEM161B homozygous hypomorphic missense variants in our recessive polymicrogyria&nbsp;(PMG) cohort. Patients carrying TMEM161B mutations exhibit striking neocortical PMG and intellectual disability. Tmem161b knockout mice fail to develop midline hemispheric cleavage, whereas knock-in of patient mutations and patient-derived brain organoids show defects in apical cell polarity and radial glial scaffolding. We found that TMEM161B modulates actin filopodia, functioning upstream of the Rho-GTPase CDC42. Our data link TMEM161B with human PMG, likely regulating radial glia apical polarity during neocortical development