A decrease in dkk1, a Wnt inhibitor, contributes to placental and fetal lipid accumulation in an obesity-prone rat model

Placenta, as the sole transport mechanism between mother and fetus, links the maternal physical state and the immediate and life-long outcomes of the offspring. The present study examined the mechanisms behind the effect of maternal obesity on placental lipid accumulation and metabolism. Pregnant Obese Prone (OP) and Obese Resistant (OR) rat strains were fed a control diet throughout gestation. Placentas were collected on gestational d21 for analysis and frozen placental sections were analyzed for fat accumulation as well as β-Catenin and Dkk1 localization. Additionally, DKK1 was overexpressed in JEG3 trophoblast cells, followed by treatment with NEFA and Oil Red O stain quantification and mRNA analysis to determine the relationship between placental DKK1 and lipid accumulation. Maternal plasma and placental NEFA and TG were elevated in OP dams, and offspring of OP dams were smaller than OR. Placental Dkk1 mRNA content was 4-fold lower in OP placentas, and there was a significant increase in β-Catenin accumulation as well as mRNA content of fat transport and TG synthesis enzymes, including Ppar-delta, Fatp1, Fat/Cd36, Lipin1, and Lipin3. There was significant lipid accumulation within the decidual zones in OP but not OR placentas, and the thickness of the decidual and junctional zones was significantly smaller in OP than OR placentas. Overexpression of DKK1 in JEG3 cells decreased lipid accumulation and the mRNA content of PPAR-Delta, FATP1, FAT/CD36, LIPIN1, and LIPIN3. Our results indicate that Dkk1 may be regulating placental lipid metabolism through Wnt-mediated mechanisms. Additionally, recent studies have suggested that maternal obesity may also program early development of non-alcoholic fatty liver disease (NAFLD), rates of which have correlated with the increase in the obesity epidemic. In the current study, livers of OP offspring had significantly increased TG content (P<0.05) and lipid accumulation when compared to offspring of OR dams. Additionally, hepatic Dkk1 mRNA content was significantly decreased in OP livers when compared to OR (P<0.05), and treating H4IIECR rat hepatocyte cells with NEFA showed that Dkk1 mRNA was also decreased in NEFA-treated cells (P<0.05) that also had lipid accumulation. Chromatin Immunoprecipitation (ChIP) analysis of the Dkk1 promoter in fetal livers showed a pattern of histone modifications associated with decreased gene transcription in OP offspring, which agrees with our gene expression data. These results demonstrate that the hepatic Dkk1 gene is epigenetically regulated via histone modification in neonatal offspring in the current model of gestational obesity, and future studies will be needed to determine whether these changes contribute to excessive hepatic lipid accumulation in offspring of obese dams.

Children's mental representations of attachment: associations with attachment security and parent-child narrative quality

The goal of this study was to examine the antecedents and correlates of children’s mental representations of attachment at 5 years (Attachment Story Completion Task, Bretherton, Ridgeway, & Cassidy, 1990; MacArthur Story Stem Battery, Bretherton, Oppenheim, Buchsbaum, Emde, & the MacArthur Narrative Group, 1990). Predictors included children’s attachment security with mothers and fathers assessed via the Attachment Q-Set (AQS, Waters, 1987) at 3 years, and parent-child narrative quality regarding positive and negative events at 5 years. Participants included 71 children and their mothers and fathers. Structural equation models (SEM) indicated that children’s attachment security exerted a significant indirect effect on children’s mental representations through parent-child narrative quality. Specifically, children’s attachment security with fathers was related to their mental representations via father-child reminiscing about positive events, and children’s attachment security with mothers was related to their mental representations via mother-child reminiscing about negative events. Results are discussed in terms of the development and implications of attachment relationships within the family context.

Searching for knowledge in the belly of the beast: diversity, social equity and the African graduate student mother's experience in US higher education

Diversity has become a buzz word in public discourse and in educational circles. Higher education institutions in the US have increasingly used this word as a cornerstone of their mission statements and have made increasing efforts to attract students from different backgrounds. As part of the increase in diversity efforts among US colleges, is a significant rise in the number of international students. Attracting international students has become a priority for U.S. universities regardless of size or location. This study examines the intersection between the structure of American educational environment and the blended identities of African Graduate Student Mothers. Within the context of contemporary diversity efforts in US educational institutions, this study examines both the structural environments and the socio-cultural constructs that affect the experiences of African graduate student mothers. Based on a qualitative research interview design, a total of nineteen African graduate student mothers at a Mid-Western University in the US were interviewed individually and in groups over a six weeks period. Results from this study show that apart from the difficult and often dehumanizing treatment African student mothers endure from immigration and consular officials in their various countries and ports of entry, they often find themselves at the margins of their various programs and departments with very little support if any. This is because most of them enroll into graduate programs after arriving as dependants of their spouses; a process that does not allow them to negotiate for departmental commitments and support prior to their arrival. Not only do these women face racial discrimination from white professors, staff and fellow students, but they also experience discrimination and hostilities from African Americans and other minority groups who see them as threats to the limited resources that are often set aside for minority groups in such institutions.