Neural ectoderm-secreted FGF initiates the expression of Nkx2.5 in cardiac progenitors via a p38 MAPK/CREB pathway

AbstractVertebrate heart development is derived from paired primordia of anterior dorsolateral mesoderm expressing Nkx2.5 and GATA4 transcription factors. Yet growth factors and intracellular pathways specifying heart precursor gene expression are poorly understood. In the present work, we investigated the signaling events initiating Nkx2.5 expression in Xenopus laevis. We describe here that fibroblast growth factor (FGF) initiates the expression of Nkx2.5 without affecting GATA4. At gastrula, FGF3 is expressed in anterior neural ectoderm, and results presented here indicate that this tissue is involved in the induction of Nkx2.5 expression in neighboring lateral tissues. Further studies indicate that the intracellular p38 MAPK and the CREB transcription factor function downstream of FGF to initiate Nkx2.5 expression. Activation of the p38 MAPK pathway and of the CREB protein is both necessary and sufficient for the initial expression of Nkx2.5. Therefore, we would like to suggest that FGF expressed in anterior neural ectoderm is a major inducer of Nkx2.5 expression in neighboring cells. In these cells, FGF activates an intracellular p38 MAPK signaling pathway and its downstream target, the CREB transcription factor, all participating in the expression of Nkx2.5 in cardiac progenitors

The Psychology of Marathon Television Viewing: Antecedents and Viewer Involvement

This study focuses on the expanding trend of marathon (“binge”) television viewing. It examines the personality antecedents of such media consumption (attachment style, depression, and self-regulation deficiency) as well as the psychological experiences of marathon viewers relative to the narrative (transportation, enjoyment) and its characters (parasocial relationship, identification). In a two-study design, theoretical models of media use and involvement, on one hand, and models of media addiction, on the other hand, are applied to predict the extent of marathon viewing and to compare it with “traditional” viewing. Results advance understanding of enjoyment and involvement theory and support cognitive theories of media addiction. At the same time, the study’s findings reveal that marathon television viewers are active both cognitively and emotionally during and after the media exposure, thus alleviating some concerns about the “problematic” nature of the “binge” viewing phenomenon

“But She Notices”: Parent-Child Communication About Anti-Latino Discrimination

Objective: In recent years, discrimination directed toward Hispanic/Latino Americans has escalated, threatening the health of North Carolina’s Hispanic/Latino children. While previous research in African American families demonstrates the ability of parent-child communication to interrupt the pathway between childhood experiences of discrimination and various poor health outcomes, this topic has not been well-studied in Hispanic/Latino families. The present study is the initial phase of a larger investigation addressing this knowledge gap by exploring how Hispanic/Latino parents discuss issues of anti-Latino and anti-immigrant discrimination, bias, and unfair treatment with their children. Methods: I developed a semi-structured interview guide based on a model of minority child development, and conducted in-depth interviews with Hispanic/Latino parent participants (N=4). Interview data were analyzed using a phenomenological approach to identify key themes, and the interconnections between themes were mapped. Results: The preliminary results illustrate 8 major strategies employed by Hispanic/Latino parents to manage and discuss anti-Latino discrimination with their children, as well as several major factors influencing parents’ facility with conducting these conversations. Conclusion: This initial phase demonstrates the feasibility of the larger investigation, which will be conducted with changes to the study protocol as determined by the present study.Master of Public Healt

p38 MAP kinase regulates the expression of XMyf5 and affects distinct myogenic programs during Xenopus development

AbstractThe p38 MAPK signaling pathway is essential for skeletal muscle differentiation in tissue culture models. We demonstrate a novel role for p38 MAPK in myogenesis during early Xenopus laevis development. Interfering with p38 MAPK causes distinct defects in myogenesis. The initial expression of Myf5 is selectively blocked, while expression of MyoD is unaffected. Expression of a subset of muscle structural genes is reduced. Convergent extension movements are prevented and segmentation of the paraxial mesoderm is delayed, probably due to the failure of cells to withdraw from the cell cycle. Myotubes are properly formed; however, at later stages, they begin to degenerate, and the boundaries between somites disappear. Significant apoptotic cell death occurs in most parts of the somites. The ventral body wall muscle derived from migratory progenitor cells of the ventral somite region is poorly formed. Our data indicate that the developmental defects caused by p38α-knockdown were mediated by the loss of XMyf5 expression. Thus, this study identifies a specific intracellular pathway in which p38 MAPK and Myf5 proteins regulate a distinct myogenic program

Sex on TV 3

Part of a series that examines the nature and extent of sexual messages conveyed on TV. Tracks changes that occur over time in the treatment of sexual topics, including references to possible risks or responsibilities. Based on a 2001-2002 program sampl

Balancing photosynthetic electron flow is critical for cyanobacterial acclimation to nitrogen limitation

AbstractNitrogen limitation forces photosynthetic organisms to reallocate available nitrogen to essential functions. At the same time, it increases the probability of photo-damage by limiting the rate of energy-demanding metabolic processes, downstream of the photosynthetic apparatus. Non-diazotrophic cyanobacteria cope with this situation by decreasing the size of their phycobilisome antenna and by modifying their photosynthetic apparatus. These changes can serve two purposes: to provide extra amino-acids and to decrease excitation pressure. We examined the effects of nitrogen limitation on the form and function of the photosynthetic apparatus. Our aim was to study which of the two demands serve as the driving force for the remodeling of the photosynthetic apparatus, under different growth conditions. We found that a drastic reduction in light intensity allowed cells to maintain a more functional photosynthetic apparatus: the phycobilisome antenna was bigger, the activity of both photosystems was higher and the levels of photosystem (PS) proteins were higher. Pre-acclimating cells to Mn limitation, under which the activity of both PSI and PSII is diminished, results in a very similar response. The rate of PSII photoinhibition, in nitrogen limited cells, was found to be directly related to the activity of the photosynthetic apparatus. These data indicate that, under our experimental conditions, photo-damage avoidance was the more prominent determinant during the acclimation process. The combinations of limiting factors tested here is by no means artificial. Similar scenarios can take place under environmental conditions and should be taken into account when estimating nutrient limitations in nature

Sex on TV 4

Part of a series that examines the nature and extent of sexual messages conveyed on TV. Tracks changes that occur over time in the treatment of sexual topics, including references to possible risks or responsibilities. Based on a 2003-2004 program sample