Maternal control of early patterning in sea urchin embryos

Sea urchin development has been studied extensively for more than a century and considered regulative since the first experimental evidence. Further investigations have repeatedly supported this standpoint by revealing the presence of inductive mechanisms that alter cell fate decisions at early cleavage stages and flexibility of development in response to environmental conditions. Some features indicate that sea urchin development is not completely regulative, but actually includes determinative events. In 16-cell embryos, mesomeres and macromeres represent multipotency, while the cell fate of most vegetal micromeres is restricted. It is known that the mature sea urchin eggs are polarized by the asymmetrical distribution of some maternal mRNAs and proteins. Spatially-distributed maternal factors are necessary for the orientation of the primary animal-vegetal axis, which is established by both maternal and zygotic mechanisms later in development. The secondary dorsal-ventral axis is conditionally specified later in development. Dorsal-ventral polarity is very liable during the early cleavages, though more recent data argue that its direction may be oriented by maternal asymmetry. In this review, we focus on the role of maternal factors in initial embryonic patterning during the first cleavages of sea urchin embryos before activation of the embryonic genome.

Maternal determinants of optimal breastfeeding and complementary feeding and their association with child undernutrition in Malawi (2015-2016)

BACKGROUND

Optimal breastfeeding and complementary feeding practices are critical to prevent child undernutrition. Despite the occurrence of child undernutrition and widespread suboptimal feeding practices in Malawi, the association of breastfeeding and complementary feeding practices and undernutrition among Malawian children remains unclear. The purpose of the study was to determine the current breastfeeding and complementary feeding practices, to identify maternal determinants of each practice, and to analyze the associations between breastfeeding and complementary feeding practices with stunting, underweight, and wasting.

METHODS

The most recent Malawi Demographic Health Survey (2015-2016) was used and data for 2294 children aged 0-23 months were included. A conceptual framework of five maternal domains: sociodemographic, health status, health behaviors, women's empowerment, and media exposure was used. Each domain contained exposure variables and the WHO Infant and Young Child Feeding indicators were used as outcome variables. All analyses were adjusted for clustering, and variables that reached a p-value of < 0.05 were considered significant in the final model.

RESULTS

Among children, 30.8% were stunted, 9.9% were underweight, and 3.7% were wasted. Many (78%) were breastfed within the first hour of birth, 89% were breastfed until their first birthday, yet 40% were not exclusively breastfed to 6 months. Only 32% met minimum dietary diversity, 23% met minimum meal frequency, 12% met minimum acceptable diet and 12% consumed iron-rich foods. Children whose mothers lived in urban areas were less likely to be breastfed within 1 hour of birth but more likely to meet minimum dietary diversity. Children whose mothers listened to radio were more likely to meet minimum meal frequency. Children (13-23 months) who met minimum meal frequency and minimum acceptable diet were less likely to be underweight.

CONCLUSIONS

Optimal breastfeeding and complementary feeding practices in Malawi remain suboptimal and child undernutrition remains problematic. Maternal characteristics from the five domains were significantly associated with optimal breastfeeding and complementary feeding indicators. Knowledge of these maternal determinants can assist in improving nutrition policies and interventions that aim to impact breastfeeding and complementary feeding practices and child growth in Malawi.

Regulation and evolution of muscle development in tunicates

For more than a century, studies on tunicate muscle formation have revealed many principles of cell fate specification, gene regulation, morphogenesis, and evolution. Here, we review the key studies that have probed the development of all the various muscle cell types in a wide variety of tunicate species. We seize this occasion to explore the implications and questions raised by these findings in the broader context of muscle evolution in chordates.

Maternal determinants of low birth weight and neonatal asphyxia in the Upper West region of Ghana

BACKGROUND

Adverse birth outcomes continue to be a global public health challenge, particularly in low resource settings. Therefore, the present study aimed at assessing maternal determinants of low birth weight and neonatal asphyxia in the Upper West region of Ghana.

METHODS

An analytical cross sectional survey was conducted among mothers who attended child welfare clinics (CWC) in six sub-districts. Pregnancy outcome data and maternal nutritional, health service and socio-demographics were obtained using a pre-tested questionnaire. Determinants of low birth weight (LBW) and neonatal asphyxia were analyzed using chi-square and multivariable logistic regression modelling.

RESULTS

The results showed that the prevalence of low birth weight and neonatal asphyxia were 8.2% and 9.3% respectively. Multiple logistic regression showed that the risk of giving birth to a LBW baby was high among mothers who consumed alcoholic beverages [AOR = 5.93; 95% CI (1.22-28.84); p = 0.03], those who had food taboos during pregnancy [AOR = 3.31; 95% CI (1.02-10.77); p = 0.047] and not having additional meals [AOR = 3.16; 95% CI (1.0-10.0); p = 0.05] during pregnancy. Neonatal asphyxia was higher among new born babies whose mothers did not receive nutritional counselling in pregnancy [AOR = 5.64; 95% CI (1.48-21.60); p = 0.01] and those who had anaemia at 36 weeks gestation [AOR = 2.69; 95% CI (0.95-7.65); p = 0.06].

CONCLUSION

Maternal dietary practices during pregnancy could positively affect birth outcome in the Upper West Region of Ghana.

Gametic synapses, nanotubes and sperm RNAs - Redefining the origin of maternal determinants

The female germline cells, i.e., the oocytes/eggs, contain a subpopulation of unique organelles and molecules (RNA and proteins) collectively called "the maternal determinants" that are indispensable for the determination of cell fate in the developing embryo. Although it has been known for some time that somatic cells deliver low-molecular-weight molecules to the oocyte/egg, the paradigm has been that the larger molecules and organelles are synthesized by the female germline cells without input from the surrounding somatic cells. However, recent discoveries of novel types of intercellular connections such as gametic synapses and tunneling nanotubes, allowing the transfer of large, externally derived molecules to the oocyte/egg, may dismantle the paradigm of the transcriptional/translational self-containment of the female gamete and add novel and unexpected aspects to the origin and identity of maternal determinants. In addition, the discovery that sperm delivers various RNAs to the egg suggests that sperm may not only epigenetically modify the egg genome but also influence or modify information contained in the maternal determinants.

When Family History Matters: The Importance of Lineage Analyses and Fate Maps for Explaining Animal Development

Initial interest in understanding how the fertilized egg becomes a multicellular animal suggested two possible answers: either the embryo came from preformed components or it arose through epigenetic processes. Extensive research during the past few decades has identified aspects of development that depend on preformed elements, such as cytoplasmic components and a cell's lineage; it also has identified aspects that depend on epigenetic processes, such as cell interactions and morphogen gradients. These advances have depended on understanding embryonic cell lineage and cell fate. This essay explains how lineage analysis and fate mapping have contributed to our current understanding of embryonic development.

Maternal determinants of timely vaccination coverage among infants in rural Bangladesh

BACKGROUND

Timely vaccination, i.e., the receipt of all scheduled vaccinations in an age-appropriate fashion, is critical for the prevention of deadly diseases in infants and achievement of the UN Millennium Development Goal to reduce infant mortality. Infants, especially in rural or underprivileged settings often receive delayed vaccinations leaving them susceptible to vaccine-preventable illnesses early in the first year of life. In this study, we examined rates of timely vaccination among 24,435 infants born in Gaibandha and Rangpur rural districts of Bangladesh from 2001 to 2007.

METHODS

Vaccinations due by 14 weeks of age and administered through routine government immunization services were assessed using interviews with enrolled mothers between 11 and 18 weeks postpartum. We created a Timely Vaccination (TV) score to classify infants as vaccinated fully and on schedule (TV=1) or not (TV=0), and used multivariable logistic regression to identify maternal characteristics associated with infant's timely vaccination status.

RESULTS

Our results suggest that only 19% of infants in this cohort received scheduled vaccinations on time by 11-18 weeks postpartum. Mothers' engagement in paid employment [OR=1.13, 95% CI: 1.03-1.23], receipt of tetanus toxoid vaccination [OR=1.24, 95% CI: 1.11-1.38], history of antenatal care [OR=1.22, 95% CI: 1.12-1.32], or higher socioeconomic status [OR=1.07, 95% CI: 1.03-1.11] were positively associated with timely vaccination of their infants. Mother's perception of small infant size at birth was negatively associated with timely vaccination [OR=0.89, 95% CI: 0.82-0.97].

CONCLUSION

Timely vaccination coverage of infants in rural Gaibandha and Rangpur districts is extremely low. This analysis identifies important shortcomings associated with the 1-year vaccination benchmark of routine immunization performance and suggests the need for specific interventions based on potential maternal determinants as well as known system and programmatic barriers of timely vaccination among infants in rural Bangladesh.