Cortisol and DHEA in development and psychopathology

Dehydroepiandrosterone (DHEA) and cortisol are the most abundant hormones of the human fetal and adult adrenals released as end products of a tightly coordinated endocrine response to stress. Together, they mediate short- and long-term stress responses and enable physiological and behavioral adjustments necessary for maintaining homeostasis. Detrimental effects of chronic or repeated elevations in cortisol on behavioral and emotional health are well documented. Evidence for actions of DHEA that offset or oppose those of cortisol has stimulated interest in examining their levels as a ratio, as an alternate index of adrenocortical activity and the net effects of cortisol. Such research necessitates a thorough understanding of the co-actions of these hormones on physiological functioning and in association with developmental outcomes. This review addresses the state of the science in understanding the role of DHEA, cortisol, and their ratio in typical development and developmental psychopathology. A rationale for studying DHEA and cortisol in concert is supported by physiological data on the coordinated synthesis and release of these hormones in the adrenal and by their opposing physiological actions. We then present evidence that researching cortisol and DHEA necessitates a developmental perspective. Age-related changes in DHEA and cortisol are described from the perinatal period through adolescence, along with observed associations of these hormones with developmental psychopathology. Along the way, we identify several major knowledge gaps in the role of DHEA in modulating cortisol in typical development and developmental psychopathology with implications for future research.     

Malleability,plasticity, and individuality: How children learn and develop in context1

ABSTRACT

This article synthesizes foundational knowledge from multiple scientific disciplines regarding how humans develop in context. Major constructs that define human development are integrated into a developmental system framework, this includes—epigenetics, neural malleability and plasticity, integrated complex skill development and learning, human variability, relationships and attachment, self-regulation, science of learning, and dynamics of stress, adversity and resilience. Specific attention is given to relational patterns, attunement, cognitive flexibility, executive function, working memory, sociocultural context, constructive development, self-organization, dynamic skill development, neural integration, relational pattern making, and adverse childhood experiences. A companion article focuses on individual-context relations, including the role of human relationships as key drivers of development, how social and cultural contexts support and/or undermine individual development, and the dynamic, idiographic developmental pathways that result from mutually influential individual-context relations across the life span. An understanding of the holistic, self-constructive character of development and interconnectedness between individuals and their physical, social, and cultural contexts offers a transformational opportunity to study and influence the children’s trajectories. Woven throughout is the convergence of the science of learning – constructive developmental web, foundational skills, mindsets (sense of belonging, self-efficacy, and growth mindset), prior knowledge and experience, motivational systems (intrinsic motivation, achievement motivation, and the Belief-Control-Expectancy Framework), metacognition, conditions for learning , cultural responsiveness and competence, and instructional and curricular design- and its importance in supporting in integrative framework for children’s development. This scientific understanding of development opens pathways for new, creative approaches that have the potential to solve seemingly intractable learning and social problems.     

Without it no music: cognition,biology and evolution of musicality

Musicality can be defined as a natural, spontaneously developing trait based on and constrained by biology and cognition. Music, by contrast, can be defined as a social and cultural construct based on that very musicality. One critical challenge is to delineate the constituent elements of musicality. What biological and cognitive mechanisms are essential for perceiving, appreciating and making music? Progress in understanding the evolution of music cognition depends upon adequate characterization of the constituent mechanisms of musicality and the extent to which they are present in non-human species. We argue for the importance of identifying these mechanisms and delineating their functions and developmental course, as well as suggesting effective means of studying them in human and non-human animals. It is virtually impossible to underpin the evolutionary role of musicality as a whole, but a multicomponent perspective on musicality that emphasizes its constituent capacities, development and neural cognitive specificity is an excellent starting point for a research programme aimed at illuminating the origins and evolution of musical behaviour as an autonomous trait.     

The Development of Logical Memorization Techniques in the Preschool and Young School Child

The role of organizational factors in memory is currently a major concern of American cognitive psychologists. The present paper replicates the generally obtained trend toward increasing recall and categorization as a direct function of age. The authors' suggestions for accelerating the development of organizational skills offer interesting hypotheses for educational psychologists.     

The crucial role and regulations of miRNAs in zebrafish development

To comprehend the events during developmental biology, fundamental knowledge about the basic machinery of regulation is a prerequisite. MicroRNA (miRNAs) act as regulators in most of the biological processes and recently, it has been concluded that miRNAs can act as modulatory factors even during developmental process from lower to higher animal. Zebrafish, because of its favorable attributes like tiny size, transparent embryo, and rapid external embryonic development, has gained a preferable status among all other available experimental animal models. Currently, zebrafish is being utilized for experimental studies related to stem cells, regenerative molecular medicine as well drug discovery. Therefore, it is important to understand precisely about the various miRNAs that controls developmental biology of this vertebrate model. In here, we have discussed about the miRNA-controlled zebrafish developmental stages with a special emphasis on different miRNA families such as miR-430, miR-200, and miR-133. Moreover, we have also reviewed the role of various miRNAs during embryonic and vascular development stages of zebrafish. In addition, efforts have been made to summarize the involvement of miRNAs in the development of different body parts such as the brain, eye, heart, muscle, and fin, etc. In each section, we have tried to fulfill the gaps of zebrafish developmental biology with the help of available knowledge of miRNA research. We hope that precise knowledge about the miRNA-regulated developmental stages of zebrafish may further help the researchers to efficiently utilize this vertebrate model for experimental purpose.     

Grist and mills: on the cultural origins of cultural learning

Cumulative cultural evolution is what 'makes us odd'; our capacity to learn facts and techniques from others, and to refine them over generations, plays a major role in making human minds and lives radically different from those of other animals. In this article, I discuss cognitive processes that are known collectively as 'cultural learning' because they enable cumulative cultural evolution. These cognitive processes include reading, social learning, imitation, teaching, social motivation and theory of mind. Taking the first of these three types of cultural learning as examples, I ask whether and to what extent these cognitive processes have been adapted genetically or culturally to enable cumulative cultural evolution. I find that recent empirical work in comparative psychology, developmental psychology and cognitive neuroscience provides surprisingly little evidence of genetic adaptation, and ample evidence of cultural adaptation. This raises the possibility that it is not only 'grist' but also 'mills' that are culturally inherited; through social interaction in the course of development, we not only acquire facts about the world and how to deal with it (grist), we also build the cognitive processes that make 'fact inheritance' possible (mills).     

Bridging epidemiology and model organisms to increase understanding of endocrine disrupting chemicals and human health effects

Concerning temporal trends in human reproductive health has prompted concern about the role of environmentally mediated risk factors. The population is exposed to chemicals present in air, water, food and in a variety of consumer and personal care products, subsequently multiple chemicals are found human populations around the globe. Recent reviews find that endocrine disrupting chemicals (EDCs) can adversely affect reproductive and developmental health. However, there are still many knowledge gaps. This paper reviews some of the key scientific concepts relevant to integrating information from human epidemiologic and model organisms to understand the relationship between EDC exposure and adverse human health effects. Additionally, areas of new insights which influence the interpretation of the science are briefly reviewed, including: enhanced understanding of toxicity pathways; importance of timing of exposure; contribution of multiple chemical exposures; and low dose effects. Two cases are presented, thyroid disrupting chemicals and anti-androgens chemicals, which illustrate how our knowledge of the relationship between EDCs and adverse human health effects is strengthened and data gaps reduced when we integrate findings from animal and human studies.     

Domestication as a model system for niche construction theory

Niche Construction Theory (NCT) provides a powerful conceptual framework for understanding how and why humans and target species entered into domesticatory relationships that have transformed Earth’s biota, landforms, and atmosphere, and shaped the trajectory of human cultural development. NCT provides fresh perspective on how niche-constructing behaviors of humans and plants and animals promote co-evolutionary interactions that alter selection pressures and foster genetic responses in domesticates. It illuminates the role of niche-altering activities in bequeathing an ecological inheritance that perpetuates the co-evolutionary relationships leading to domestication, especially as it pertains to traditional ecological knowledge and the transmission of learned behaviors aimed at enhancing returns from local environments. NCT also provides insights into the contexts and mechanisms that promote cooperative interactions in both humans and target species needed to sustain niche-constructing activities, ensuring that these activities produce an ecological inheritance in which domesticates play an increasing role. A NCT perspective contributes to on-going debates in the social sciences over explanatory frameworks for domestication, in particular as they pertain to issues of reciprocal causation, co-evolution, and the role of human intentionality. Reciprocally, domestication provides a model system for evaluating on-going debates in evolutionary biology concerning the impact of niche construction, phenotypic plasticity, extra-genetic inheritance, and developmental bias in shaping the direction and tempo of evolutionary change.     

Learning developmental biology has priority in the life sciences curriculum in Singapore

Singapore has embraced the life sciences as an important discipline to be emphasized in schools and universities. This is part of the nation's strategic move towards a knowledge-based economy, with the life sciences poised as a new engine for economic growth. In the life sciences, the area of developmental biology is of prime interest, since it is not just intriguing for students to know how a single cell can give rise to a complex, coordinated, functional life that is multicellular and multifaceted, but more importantly, there is much in developmental biology that can have biomedical implications. At different levels in the Singapore educational system, students are exposed to various aspects of developmental biology. The author has given many guest lectures to secondary (ages 12-16) and high school (ages 17-18) students to enthuse them about topics such as embryo cloning and stem cell biology. At the university level, some selected topics in developmental biology are part of a broader course which caters for students not majoring in the life sciences, so that they will learn to comprehend how development takes place and the significance of the knowledge and impacts of the technologies derived in the field. For students majoring in the life sciences, the subject is taught progressively in years two and three, so that students will gain specialist knowledge in developmental biology. As they learn, students are exposed to concepts, principles and mechanisms that underlie development. Different model organisms are studied to demonstrate the rapid advances in this field and to show the interconnectivity of developmental themes among living things. The course inevitably touches on life and death matters, and the social and ethical implications of recent technologies which enable scientists to manipulate life are discussed accordingly, either in class, in a discussion forum, or through essay writing.     

The thioredoxin-like fold: hidden domains in protein disulfide isomerases and other chaperone proteins

Although protein disulphide isomerase (PDI) has been known for nearly 40 years, several new PDIs have recently been described that reveal a remarkable diversity in both structure and function. This article reviews our current knowledge of the PDI family members and identifies four novel PDIs in the human genome. These include human transmembrane proteins that have C. elegans or Drosophila orthologues for which a developmental role has been proven. Their role in development, together with other functional roles for PDIs such as conferring resistance to apoptosis under hypoxia and a potential role in the oxygen-sensing apparatus are discussed.     

Understanding Human Lung Development through In Vitro Model Systems

An abundance of information about lung development in animal models exists; however, comparatively little is known about lung development in humans. Recent advances using primary human lung tissue combined with the use of human in vitro model systems, such as human pluripotent stem cell-derived tissue, have led to a growing understanding of the mechanisms governing human lung development. They have illuminated key differences between animal models and humans, underscoring the need for continued advancements in modeling human lung development and utilizing human tissue. This review discusses the use of human tissue and the use of human in vitro model systems that have been leveraged to better understand key regulators of human lung development and that have identified uniquely human features of development. This review also examines the implementation and challenges of human model systems and discusses how they can be applied to address knowledge gaps.     

Protein tyrosine phosphatases: dual-specificity phosphatases in health and disease

Dual-specificity phosphatases (DSPs) constitute a subfamily of protein tyrosine phosphatases (PTPs) that dephosphorylates phospho-Tyr, phospho-Ser and nonproteinaceous substrates. DSPs are involved in the regulation of both developmental and postnatal essential processes, such as early embryogenesis, placental development and immune responses. Several DSP genes are implicated in familial and sporadic human diseases, including tumor-related, neurological and muscle disorders, and cardiovascular and inflammatory diseases. This association ranges from disease-causative mutations to disease-risk-prone single-nucleotide polymorphisms, promoter methylation or gene duplication (most often in cancer). Deconvolution of the role of DSPs in disease is challenging. The enzymes' activities are regulated at many levels and they form part of extensive, intricate networks with other signaling components. Here, we review current knowledge of the role of cysteine-based PTP-domain DSPs in health and disease, and their suitability as putative therapeutic targets for drugs is discussed.     

MODELING PHENOTYPIC PLASTICITY IN GROWTH TRAJECTORIES: A STATISTICAL FRAMEWORK

Phenotypic plasticity, that is multiple phenotypes produced by a single genotype in response to environmental change, has been thought to play an important role in evolution and speciation. Historically, knowledge about phenotypic plasticity has resulted from the analysis of static traits measured at a single time point. New insight into the adaptive nature of plasticity can be gained by an understanding of how organisms alter their developmental processes in a range of environments. Recent advances in statistical modeling of functional data and developmental genetics allow us to construct a dynamic framework of plastic response in developmental form and pattern. Under this framework, development, genetics, and evolution can be synthesized through statistical bridges to better address how evolution results from phenotypic variation in the process of development via genetic alterations.     

Developmental toxicity screening in zebrafish

Given the ever-increasing toxic exposure ubiquitously present in our environment as well as emerging evidence that these exposures are hazardous to human health, the current rodent-based regulations are proving inadequate. In the process of overhauling risk assessment methodology, a nonrodent test organism, the zebrafish, is emerging as tractable for medium- and high-throughput assessments, which may help to accelerate the restructuring of standards. Zebrafish have high developmental similarity to mammals in most aspects of embryo development, including early embryonic processes, and on cardiovascular, somite, muscular, skeletal, and neuronal systems. Here, we briefly describe the development of these systems and then chronicle the toxic impacts assessed following chemical exposure. We also compare the available data in zebrafish toxicity assays with two databases containing mammalian toxicity data. Finally, we identify gaps in our collective knowledge that are ripe for future studies.