No abstract

Failure to properly establish the left–right (L/R) axis is a major cause of congenital heart defects in humans, but how L/R patterning of the embryo leads to asymmetric cardiac morphogenesis is still unclear. We find that asymmetric Nodal signaling on the left and Bmp signaling act in parallel to establish zebrafish cardiac laterality by modulating cell migration velocities across the L/R axis. Moreover, we demonstrate that Nodal plays the crucial role in generating asymmetry in the heart and that Bmp signaling via Bmp4 is dispensable in the presence of asymmetric Nodal signaling. In addition, we identify a previously unappreciated role for the Nodal-transcription factor FoxH1 in mediating cell responsiveness to Bmp, further linking the control of these two pathways in the heart. The interplay between these TGFβ pathways is complex, with Nodal signaling potentially acting to limit the response to Bmp pathway activation and the dosage of Bmp signals being critical to limit migration rates. These findings have implications for understanding the complex genetic interactions that lead to congenital heart disease in humans.

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The cytoskeleton is the hallmark of eukaryotic evolution. The molecular and architectural aspects of the cytoskeleton have been playing a prominent role in our understanding of the origin and evolution of eukaryotes. In this study, we seek to investigate the cytoskeleton architecture and its evolutionary significance in understudied amoeboid lineages belonging to Amoebozoa. These amoebae primarily use cytoplasmic extensions supported by the cytoskeleton to perform important cellular processes such as movement and feeding. Amoeboid structure has important taxonomic significance, but, owing to techniques used, its potential significance in understanding diversity of the group has been seriously compromised, leading to an under-appreciation of its value. Here, we used immunocytochemistry and confocal microscopy to study the architecture of microtubules (MTs) and F-actin in diverse groups of amoebae. Our results demonstrate that all Amoebozoa examined are characterized by a complex cytoskeletal array, unlike what has been previously thought to exist. Our results not only conclusively demonstrate that all amoebozoans possess complex cytoplasmic MTs, but also provide, for the first time, a potential synapomorphy for the molecularly defined Amoebozoa clade. Based on this evidence, the last common ancestor of amoebozoans is hypothesized to have had a complex interwoven MT architecture limited within the granular cell body. We also generate several cytoskeleton characters related to MT and F-actin, which are found to be robust for defining groups in deep and shallow nodes of Amoebozoa.

Teen dating violence (TDV) affects millions of youth in the United States and globally each year. A systematic review was conducted to examine the help-seeking intentions and behaviors of youth between the ages of 12 and 19 based on racial and ethnic differences. Considering the high prevalence of TDV among racially and ethnically diverse youth, previous systematic reviews have recommended that future scholarship address help-seeking intentions and behaviors among racially and ethnically diverse youth. The methodologies and results of TDV and help-seeking studies published since 2000 were reviewed and analyzed. A systematic search of peer-reviewed journal articles published in English was conducted using an electronic search. The rigorous search identified 10 studies that addressed help-seeking intentions and behaviors and racial and ethnic differences in youth meeting eligibility requirements. The search yielded few studies, indicating a need to conduct future research in this area. The strength of the studies’ methodologies limited generalizability and external validity. The studies primarily addressed differences among African American and Latino youth. Youth relied on informal sources of support, with youth from both groups preferring to seek help from parents and friends. Mistrust, lack of closeness, and feelings of mistrust, shame, and embarrassment informed youths’ help-seeking intentions and behaviors. Racially and ethnically specific factors such as negative perceptions of father figures, familism, acculturation, and traditional gender role notions were identified as barriers to help-seeking. As part of appraising and synthesizing the evidence, recommendations for research, practice, and policy are presented.