Developmental Questions Research Articles

Jak-Stat pathway induces Drosophila follicle elongation by a gradient of apical contractility.

Tissue elongation and its control by spatiotemporal signals is a major developmental question. Currently, it is thought that Drosophila ovarian follicular epithelium elongation requires the planar polarization of the basal domain cytoskeleton and of the extra-cellular matrix, associated with a dynamic process of rotation around the anteroposterior axis. Here we show, by careful kinetic analysis of fat2 mutants, that neither basal planar polarization nor rotation is required during a first phase of follicle elongation. Conversely, a JAK-STAT signaling gradient from each follicle pole orients early elongation. JAK-STAT controls apical pulsatile contractions, and Myosin II activity inhibition affects both pulses and early elongation. Early elongation is associated with apical constriction at the poles and with oriented cell rearrangements, but without any visible planar cell polarization of the apical domain. Thus, a morphogen gradient can trigger tissue elongation through a control of cell pulsing and without a planar cell polarity requirement.

The effect of age on vigilance: a longitudinal study with a precocial species

AbstractVigilance allows prey species to detect predators before it is too late to escape. While the adaptive value of vigilance has become clearer over the years, developmental questions have attracted little attention. I explored the effect of age and group size on vigilance in a precocial species, the domestic fowl (Gallus gallus domesticus). I recorded vigilance in groups of various sizes in juveniles and one year later in adults. Vigilance decreased with group size in juveniles and to a lesser extent in adults. Juveniles tested alone showed longer feeding and vigilance bouts than adults reflecting their inexperience with predation threats and more rapid satiation, respectively. Adults in larger groups were more vigilant reflecting the need to monitor aggressive conspecifics in addition to predators. Gradual acquisition of information about risk posed by predators and conspecifics and feeding constraints influenced the expression of vigilance as a function of age in this species.

Reflections on and Future Directions in Humility and Forgiveness Research

Research on humility and forgiveness has reached an important milestone. Scholars are transitioning from largely studying these character strengths in convenience samples (typically university undergraduates) to conducting studies in diverse samples that more accurately reflect the overall adult population in the United States. At important junctures like these, the field needs to both look back and learn from the work to date, as well as to look forward at the new questions that can now bed addressed with these expanded samples. In looking back, previous scholarship demonstrates a strong synthesis between forgiveness and humility, indicating the value of examining these characteristics together. Noel Card (this issue)’s meta-analyses of previous studies’ use of forgiveness and humility measures is also quite timely as it highlights the strengths of various measures, as well as where future measurement work is still needed. In looking forward, the remaining four articles within this issue (Krause, this issue; Hill, this issue; Webster, Ajrouch, & Antonucci, this issue; Antonucci, Ajrouch, Webster, & Birditt, this issue) raise, and begin to address, important developmental questions surrounding forgiveness and humility, such as between group differences, the role of social context, the impact of life stage, and adversity’s possible influence. Cumulatively, these papers point towards the critical questions the field of forgiveness and humility scholars need to address, especially as interest grows in application and intervention development.

Small molecule screen in embryonic zebrafish using modular variations to target segmentation

Small molecule in vivo phenotypic screening is used to identify drugs or biological activities by directly assessing effects in intact organisms. However, current screening designs may not exploit the full potential of chemical libraries due to false negatives. Here, we demonstrate a modular small molecule screen in embryonic zebrafish that varies concentration, genotype and timing to target segmentation disorders, birth defects that affect the spinal column. By testing each small molecule in multiple interrelated ways, this screen recovers compounds that a standard screening design would have missed, increasing the hit frequency from the chemical library three-fold. We identify molecular pathways and segmentation phenotypes, which we share in an open-access annotated database. These hits provide insight into human vertebral segmentation disorders and myopathies. This modular screening strategy is applicable to other developmental questions and disease models, highlighting the power of relatively small chemical libraries to accelerate gene discovery and disease study.

Current methods and limitations for longitudinal fMRI analysis across development

The human brain is remarkably plastic. The brain changes dramatically across development, with ongoing functional development continuing well into the third decade of life and substantial changes occurring again in older age. Dynamic changes in brain function are thought to underlie the innumerable changes in cognition, emotion, and behavior that occur across development. The brain also changes in response to experience, which raises important questions about how the environment influences the developing brain. Longitudinal functional magnetic resonance imaging (fMRI) studies are an essential means of understanding these developmental changes and their cognitive, emotional, and behavioral correlates. This paper provides an overview of common statistical models of longitudinal change applicable to developmental cognitive neuroscience, and a review of the functionality provided by major software packages for longitudinal fMRI analysis. We demonstrate that there are important developmental questions that cannot be answered using available software. We propose alternative approaches for addressing problems that are commonly faced in modeling developmental change with fMRI data.

What infant-directed speech tells us about the development of compensation for assimilation

In speech addressed to adults, words are seldom realized in their canonical, or citation, form. For example, the word ‘green’ in the phrase ‘green beans’ can often be realized as ‘greem’ due to English place assimilation, where word-final coronals take on the place of articulation of neighboring velars. In such a situation, adult listeners readily ‘undo’ the assimilatory process and perceive the underlying intended lexical form of ‘greem’ (i.e. they access the lexical representation ‘green’). An interesting developmental question is how children, with their limited lexical knowledge, come to cope with phonologically conditioned connected speech processes such as place assimilation. Here, we begin to address this issue by examining the occurrence of place assimilation in the input to English-learning 18-month-olds. Perceptual and acoustic analyses of elicited speech, as well asanalysis of a corpus of spontaneous speech, all converge on the finding that caregivers do not spoon-feed their children canonical tokens of words. Rather, infant-directed speech contains just as many non-canonical realizations of words in place assimilation contexts asadult-directed speech. Implications for models of developmental speech perception are discussed.

Making muscle: skeletal myogenesis in vivo and in vitro.

Skeletal muscle is the largest tissue in the body and loss of its function or its regenerative properties results in debilitating musculoskeletal disorders. Understanding the mechanisms that drive skeletal muscle formation will not only help to unravel the molecular basis of skeletal muscle diseases, but also provide a roadmap for recapitulating skeletal myogenesis in vitro from pluripotent stem cells (PSCs). PSCs have become an important tool for probing developmental questions, while differentiated cell types allow the development of novel therapeutic strategies. In this Review, we provide a comprehensive overview of skeletal myogenesis from the earliest premyogenic progenitor stage to terminally differentiated myofibers, and discuss how this knowledge has been applied to differentiate PSCs into muscle fibers and their progenitors in vitro.

Children benefit differently from night- and day-time sleep in motor learning

Motor skill acquisition occurs while practicing (on-line) and when asleep or awake (off-line). However, developmental questions still remain about whether children of various ages benefit similarly or differentially from night- and day-time sleeping. The likely circadian effects (time-of-day) and the possible between-test-interference (order effects) associated with children's off-line motor learning are currently unknown. Therefore, this study examines the contributions of over-night sleeping and mid-day napping to procedural skill learning. One hundred and eight children were instructed to practice a finger sequence task using computer keyboards. After an equivalent 11-h interval in one of the three states (sleep, nap, wakefulness), children performed the same sequence in retention tests and a novel sequence in transfer tests. Changes in the movement time and sequence accuracy were evaluated between ages (6–7, 8–9, 10–11years) during practice, and from skill training to retrievals across three states. Results suggest that night-time sleeping and day-time napping improved the tapping speed, especially for the 6-year-olds. The circadian factor did not affect off-line motor learning in children. The interference between the two counter-balanced retrieval tests was not found for the off-line motor learning. This research offers possible evidence about the age-related motor learning characteristics in children and a potential means for enhancing developmental motor skills. The dynamics between age, experience, memory formation, and the theoretical implications of motor skill acquisition are discussed.

II. MORE THAN JUST CONVENIENT: THE SCIENTIFIC MERITS OF HOMOGENEOUS CONVENIENCE SAMPLES.

Despite their disadvantaged generalizability relative to probability samples, nonprobability convenience samples are the standard within developmental science, and likely will remain so because probability samples are cost-prohibitive and most available probability samples are ill-suited to examine developmental questions. In lieu of focusing on how to eliminate or sharply reduce reliance on convenience samples within developmental science, here we propose how to augment their advantages when it comes to understanding population effects as well as subpopulation differences. Although all convenience samples have less clear generalizability than probability samples, we argue that homogeneous convenience samples have clearer generalizability relative to conventional convenience samples. Therefore, when researchers are limited to convenience samples, they should consider homogeneous convenience samples as a positive alternative to conventional (or heterogeneous) convenience samples. We discuss future directions as well as potential obstacles to expanding the use of homogeneous convenience samples in developmental science.

Tokindo S. Okada.

Tokindo S. Okada.

Social Buffering of Stress in Development: A Career Perspective

This review provides a broad overview of my research group’s work on social buffering in human development in the context of the field. Much of the focus is on social buffering of the hypothalamic-pituitary-adrenocortical (HPA) system, one of the two major arms of the mammalian stress system. This focus reflects the centrality of the HPA system in research on social buffering in the fields of developmental psychobiology and developmental science. However, buffering of the cardiovascular and autonomic nervous system is also discussed. The central developmental question in this area derives from attachment theory, which argues that the infant’s experience of stress and arousal regulation in the context of her early attachment relationships is not an immature form of social buffering experienced in adulthood but rather the foundation out of which individual differences in the capacity to gain stress relief from social partners emerges. The emergence of social buffering in infancy, changes in social buffering throughout childhood and adolescence, the influence of early experience on later individual differences in social buffering, and critical gaps in our knowledge are described.

Public–Private Partnerships in Developing Countries

First used in developed markets, public–private partnerships (or PPPs) are being increasingly used to deliver critical infrastructure projects within developing countries. The success in developed markets is, however, unlikely to be easily transferrable to developing markets, and the usefulness of the contractual framework unpinning PPPs in such countries is worth questioning. In particular, a number of important developmental questions need to be answered. Are developing countries’ economic objectives best achieved through PPPs? Can developing country’s institutions support successful PPP procurement? Does a pipeline of PPP projects in a developing country ensure the growth of high-skilled jobs in the country? By exploring the experiences of PPP procurement in Chile, this article draws the conclusion that it would be in the best interest of developing countries to require domestic or local involvement within PPP consortiums, either through domestic ownership or in domestic/foreign construction partnering. Such local involvement is most likely to ensure the development of domestic engineering and construction companies and mitigate the potentially negative effects of an infrastructure market dominated by foreign influence. PPPs have been lauded for providing the ‘best of both worlds’ of private and public involvement. But the complex contractual structuring, sophisticated financing and robust institutional support involved, make PPPs an inaccessible tool for many developing countries. Outside of Australasia, Europe and North America, Chile has enjoyed some of the greatest success in promoting infrastructure development through PPPs. Since 1991, Chile has completed more than 50 PPPs, totalling over US$12 billion in capital investment in its roads, hospitals, ports and electricity system, and has been held out as a model for other less developed nations to follow (Hill, 2011, p. 189). What institutional prerequisites do developing countries need before PPPs become a viable option for infrastructure procurement? What can developing countries learn from Chile’s experiences with PPPs? From a developmental perspective, what could Chile have improved in designing its PPP programme? Split into three parts, this article seeks to answer each of these questions. ‘PPP Overview’ outlines relevant definitions, the various PPP contractual structures, which prerequisites make PPPs most effective and how PPPs encourage competition. ‘The Chilean PPP Case Study’ explores in greater detail the history of PPPs in Chile, the country’s institutional framework and some of the key outcomes from its concessions programme. Finally, ‘The Case for Domestic Involvement’ focuses on a noteworthy omission from the Chilean PPP model, requirements for local involvement. It is the author’s view that other developing countries will enjoy longer term benefits from PPPs by establishing a stance supporting the meaningful involvement of domestic companies and should, therefore, encourage PPPs not only for the public–private collaboration but also for the domestic–foreign cooperation they can foster.

Comparing within-person effects from multivariate longitudinal models.

Several multivariate models are motivated to answer similar developmental questions regarding within-person (intraindividual) effects between 2 or more constructs over time, yet the within-person effects tested by each model are distinct. In this article, the authors clarify the types of within-person inferences that can be made from each model. Whereas previous research has focused on detecting whether within-person effects exist over development, the present work can be used to understand the nature of these relationships. The authors compare each modeling approach using an example investigating the concurrent development of mother-child closeness and mother-child conflict. The findings demonstrate that fundamentally different conclusions about developmental processes may be reached depending on which model is used, and a framework is demonstrated for making sense of seemingly contradictory findings. (PsycINFO Database Record

Application of Impermeable Barriers Combined with Candidate Factor Soaked Beads to Study Inductive Signals in the Chick.

The chick embryo provides a superb vertebrate model that can be used to dissect developmental questions in a direct way. Its accessibility and robustness following surgical intervention are key experimental strengths. Mica plates were the first barriers used to prevent chick limb bud initiation1. Protocols that use aluminum foil as an impermeable barrier to wing bud or leg bud induction and or initiation are described. We combine this technique with bead placement lateral to the barrier to exogenously supply candidate endogenous factors that have been blocked by the barrier. The results are analyzed using in situ hybridization of subsequent gene expression. Our main focus is on the role of retinoic acid signaling in the induction and later initiation of the chick embryo fore and hindlimb. We use BMS 493 (an inverse agonist of retinoic acid receptors (RAR)) soaked beads implanted in the lateral plate mesoderm (LPM) to mimic the effect of a barrier placed between the somites (a source of retinoic acid (RA)) and the LPM from which limb buds grow. Modified versions of these protocols could also be used to address other questions on the origin and timing of inductive cues. Provided the region of the chick embryo is accessible at the relevant developmental stage, a barrier could be placed between the two tissues and consequent changes in development studied. Examples may be found in the developing brain, axis extension and in organ development, such as liver or kidney induction.

Application of Impermeable Barriers Combined with Candidate Factor Soaked Beads to Study Inductive Signals in the Chick

The chick embryo provides a superb vertebrate model that can be used to dissect developmental questions in a direct way. Its accessibility and robustness following surgical intervention are key experimental strengths. Mica plates were the first barriers used to prevent chick limb bud initiation1. Protocols that use aluminum foil as an impermeable barrier to wing bud or leg bud induction and or initiation are described. We combine this technique with bead placement lateral to the barrier to exogenously supply candidate endogenous factors that have been blocked by the barrier. The results are analyzed using in situ hybridization of subsequent gene expression. Our main focus is on the role of retinoic acid signaling in the induction and later initiation of the chick embryo fore and hindlimb. We use BMS 493 (an inverse agonist of retinoic acid receptors (RAR)) soaked beads implanted in the lateral plate mesoderm (LPM) to mimic the effect of a barrier placed between the somites (a source of retinoic acid (RA)) and the LPM from which limb buds grow. Modified versions of these protocols could also be used to address other questions on the origin and timing of inductive cues. Provided the region of the chick embryo is accessible at the relevant developmental stage, a barrier could be placed between the two tissues and consequent changes in development studied. Examples may be found in the developing brain, axis extension and in organ development, such as liver or kidney induction.

Building media history from fragments: a material history of Philip Carpenter’s manufacturing practice

This article will present methods for a material analysis of historical objects. I reflect on my own research practice and show how I use close study of objects and material fragments to reveal the manufacturing and retail infrastructures surrounding the instruments of early nineteenth-century optician, Philip Carpenter. I consider the methodologies of different media historians and suggest ways of expanding a focused material study into a broader historical framework. Finally, I use the work of historian Fernand Braudel to suggest methods for developing big histories that can answer larger structural and developmental questions beyond the focus of micro-historical frameworks.

Embryonic Development of the Deer Mouse, Peromyscus maniculatus.

Deer mice, or Peromyscus maniculatus, are an emerging model system for use in biomedicine. P. maniculatus are similar in appearance to laboratory mice, Mus musculus, but are more closely related to hamsters than to Mus. The laboratory strains of Peromyscus have captured a high degree of the genetic variability observed in wild populations, and are more similar to the genetic variability observed in humans than are laboratory strains of Mus. The Peromyscus Genetic Stock Center at the University of South Carolina maintains several lines of Peromyscus harboring mutations that result in developmental defects. We present here a description of P. maniculatus development from gastrulation to late gestation to serve as a guide for researchers interested in pursuing developmental questions in Peromyscus.

Comparing the stability of psychopathy scores in adolescents versus adults: How often is “fledgling psychopathy” misdiagnosed?

Author(s): Cauffman, E; Skeem, J; Dmitrieva, J; Cavanagh, C | Abstract: Can psychopathy be identified as accurately during adolescence as adulthood? To address this developmental question, this study compared the stability of scores on the leading measure of psychopathy, the Psychopathy Checklist (PCL), among 202 adolescent (M = 15.8 years, SD = 0.89) and 134 adult (M = 27.5, SD = 1.08) offenders. Over a 2-year period, adolescents' total scores on the PCL (r =.33) were less stable than those of adults (r =.71). Adolescents' baseline PCL scores also weakly predicted psychopathy classifications 2 years later (AUC =.62), particularly compared with those of adults (AUC =.85). Finally, increases in psychosocial maturity over time predicted decreases in PCL scores for adolescents, but not adults. These results raise questions about reliance upon psychopathy measures to inform decisions about youthful offenders that will have long-term consequences.

Gli epistolari cristiani dei primi cinque secoli e il trasformarsi delle lettere

The immense wealth of Greek and Latin Christian epistolography shows that in the first five centuries, the type of the letter reflects particularly the numerous topics in which theological and doctrinal issues, ecclesial and liturgical matters, and moral and social developmental questions are addressed. The epistolary genre increasingly becomes richer and more diversified as each letter bears witness to the faith and culture of its author. The pedagogical purpose remains dominant while the contents reflect the many issues and problems that concern both the sender and receiver in matters of doctrine, the Church, and the reality of social life. The line of argument and style indicate at the same time the author’s culture and heritage as received from the classical tradition.

Calling for a developmental perspective on action-based consciousness.

Human newborns can resolve some response conflicts in order to adapt their behaviour, suggesting that the newborn has consciousness according to Morsella et al.'s framework. However, we pose a range of developmental questions regarding Morsella et al.'s account, especially concerning the role of consciousness in the development of action.