Dissecting the First Transcriptional Divergence During Human Embryonic Development

The trophoblast cell lineage is specified early at the blastocyst stage, leading to the emergence of the trophectoderm and the pluripotent cells of the inner cell mass. Using a double mRNA amplification technique and a comparison with transcriptome data on pluripotent stem cells, placenta, germinal and adult tissues, we report here some essential molecular features of the human mural trophectoderm. In addition to genes known for their role in placenta (CGA, PGF, ALPPL2 and ABCG2), human trophectoderm also strongly expressed Laminins, such as LAMA1, and the GAGE Cancer/Testis genes. The very high level of ABCG2 expression in trophectoderm, 7.9-fold higher than in placenta, suggests a major role of this gene in shielding the very early embryo from xenobiotics. Several genes, including CCKBR and DNMT3L, were specifically up-regulated only in trophectoderm, indicating that the trophoblast cell lineage shares with the germinal lineage a transient burst of DNMT3L expression. A trophectoderm core transcriptional regulatory circuitry formed by 13 tightly interconnected transcription factors (CEBPA, GATA2, GATA3, GCM1, KLF5, MAFK, MSX2, MXD1, PPARD, PPARG, PPP1R13L, TFAP2C and TP63), was found to be induced in trophectoderm and maintained in placenta. The induction of this network could be recapitulated in an in vitro trophoblast differentiation model

Pooled biological specimens for human biomonitoring of environmental chemicals: Opportunities and limitations

Biomonitoring has become the ‘gold standard’ in assessing chemical exposures, and plays an important role in risk assessment. The pooling of biological specimens – combining multiple individual specimens into a single sample – can be used in biomonitoring studies to monitor levels of exposure and identify exposure trends, or to identify susceptible populations in a cost-effective manner. Pooled samples provide an estimate of central tendency, and may also reveal information about variation within the population. The development of a pooling strategy requires careful consideration of the type and number of samples collected, the number of pools required, and the number of specimens to combine per pool in order to maximize the type and robustness of the data. Creative pooling strategies can be used to explore exposure-outcome associations, and extrapolation from other larger studies can be useful in identifying elevated exposures in specific individuals. The use of pooled specimens is advantageous as it saves significantly on analytical costs, may reduce the time and resources required for recruitment, and in certain circumstances, allows quantification of samples approaching the limit of detection. In addition, use of pooled samples can provide population estimates while avoiding ethical difficulties that may be associated with reporting individual results

Embrace Chattering Students: They May Be Building Community and Interest in Your Class

When students chatter in class it can be disruptive, but could that chatter also have some redeeming qualities? We asked students to keep track of their social interactions in a particular class. On days when students had more social interactions than usual, they reported a greater sense of belonging, which was, in turn, related to greater class enjoyment (i.e., a within-person effect). Further, students who tended to have more social interactions than others reported a greater sense of belonging, which was, in turn, related to greater class enjoyment (i.e., a between-person effect). These results held when examining daily ratings of social interactions, belonging, and class enjoyment, and when examining overall end-of-semester ratings. Critically, higher average daily feelings of belonging mediated the effect of the number of average daily classroom interactions on students? end-of-semester class enjoyment and marginally on grades. For educators, promoting peer-to-peer conversation may create a positive effect by which students judge the overall class experience positively

Taking stock of self-control: A meta-analysis of how self-control affects a wide range of behaviors

Given assertions of the theoretical, empirical, and practical importance of self-control, this meta-analytic study sought to review evidence concerning the relationship between dispositional self-control and behavior. The authors provide a brief overview over prominent theories of self-control, identifying implicit assumptions surrounding the effects of self-control that warrant empirical testing. They report the results of a meta-analysis of 102 studies (total N = 32,648) investigating the behavioral effects of self-control using the Self-Control Scale, the Barratt Impulsiveness Scale, and the Low Self-Control Scale. A small to medium positive effect of self-control on behavior was found for the three scales. Only the Self-Control Scale allowed for a fine-grained analysis of conceptual moderators of the self-control behavior relation. Specifically, self-control (measured by the Self-Control Scale) related similarly to the performance of desired behaviors and the inhibition of undesired behaviors, but its effects varied dramatically across life domains (e.g., achievement, adjustment). In addition, the associations between self-control and behavior were significantly stronger for automatic (as compared to controlled) behavior and for imagined (as compared to actual) behavior. © 2012 Society for Personality and Social Psychology, Inc