Positioning adolescence in the developmental timeline.

Adolescence, the second decade of life, bridges childhood and adulthood, but also represents a host of unique experiences that impact health and well-being. Lifespan theories often emphasize the continuity of individual characteristics and their contexts from childhood to adolescence, underscoring the distal influence of childhood experiences. Yet, adolescence is marked by transitions that may provoke discontinuities, particularly within individuals, their contexts, and their interactions within those contexts. These discontinuities occur at varied times, orders, and intensities for individual youth, suggesting that adolescence may be a developmental turning point where earlier life experiences may be mediated, reversed, or transformed by proximal events. This perspective piece emphasizes the importance of considering transitions, discontinuities, and developmental turning points in adolescence as well as their potential to explain heterogeneity in adolescent and adult outcomes. We explore one biological and one contextual transition in adolescence and highlight innovative theories and methods for investigating continuity and discontinuity dynamics across development, which could lead to new insights related to the adolescent period and its importance in shaping future life trajectories.

Plant domestication: setting biological clocks.

Through domestication of wild species, humans have induced large changes in the developmental and circadian clocks of plants. As a result of these changes, modern crops are more productive and adaptive to contrasting environments from the center of origin of their wild ancestors, albeit with low genetic variability and abiotic stress tolerance. Likewise, a complete restructuring of plant metabolic timekeeping probably occurred during crop domestication. Here, we highlight that contrasting timings among organs in wild relatives of crops allowed them to recognize environmental adversities faster. We further propose that connections among biological clocks, which were established during plant domestication, may represent a fundamental source of genetic variation to improve crop resilience and yield.

Developmental Trajectories of Self-, Other-, and Dual-Harm across Adolescence: The Role of Relationships with Peers and Teachers.

INTRODUCTION: We investigated the longitudinal course of self-, other-, and dual-harm in adolescents, focusing on the infliction of physical injury on oneself, another person, or both parties, respectively. We examined the within-person transitions between these types of harm and whether relationships with peers and teachers predict individual harm trajectories. METHODS: We used community-representative longitudinal data (N = 1,482; 52% male; 50% both parents born abroad). The participants self-reported self- and other-harm at 13, 15, 17, and 20 years. We assigned them to groups with self-, other-, dual- or no harm at specific assessments. Bullying victimization and relationship quality with classmates and teachers were assessed at 13 and 17. We estimated transition probabilities between the harm groups using latent Markov chain models. RESULTS: At age 13, 3% of the sample engaged in dual-harm, 10% in self-harm only, and 7% in other-harm only. These percentages decreased in late adolescence. Initial dual-harm was often followed by sex-specific single-harm: most of the female participants transitioned to self-harm, and male participants to other-harm. Those in the initial dual-harm group were less likely to stop harming than those in the initial single-harm groups (p < 0.05). Adverse relationship experiences generally predicted harm. A positive teacher-student bond was associated with the cessation of single-harm. CONCLUSION: Single- and dual-harm in the form of physical injury typically emerge by mid-adolescence. After this point, adolescents commonly maintain harm, especially those who have presented with dual-harm. Helping adolescents cope with adverse relationship experiences and creating opportunities for positive relationship experiences could address these harmful behaviors.

The developmentally timed decay of an essential microRNA family is seed-sequence dependent.

MicroRNA (miRNA) abundance is tightly controlled by regulation of biogenesis and decay. Here, we show that the mir-35 miRNA family undergoes selective decay at the transition from embryonic to larval development in C. elegans. The seed sequence of the miRNA is necessary and largely sufficient for this regulation. Sequences outside the seed (3' end) regulate mir-35 abundance in the embryo but are not necessary for sharp decay at the transition to larval development. Enzymatic modifications of the miRNA 3' end are neither prevalent nor correlated with changes in decay, suggesting that miRNA 3' end display is not a core feature of this mechanism and further supporting a seed-driven decay model. Our findings demonstrate that seed-sequence-specific decay can selectively and coherently regulate all redundant members of a miRNA seed family, a class of mechanism that has great biological and therapeutic potential for dynamic regulation of a miRNA family's target repertoire.

Deposition and eviction of histone variants define functional chromatin states in plants.

The organization of DNA with histone proteins into chromatin is fundamental for the regulation of gene expression. Incorporation of different histone variants into the nucleosome together with post-translational modifications of these histone variants allows modulating chromatin accessibility and contributes to the establishment of functional chromatin states either permissive or repressive for transcription. This review highlights emerging mechanisms required to deposit or evict histone variants in a timely and locus-specific manner. This review further discusses how assembly of specific histone variants permits to reinforce transmission of chromatin states during replication, to maintain heterochromatin organization and stability and to reprogram existing epigenetic information.

The hidden half comes into the spotlight: Peeking inside the black box of root developmental phases.

Efficient use of natural resources (e.g., light, water, and nutrients) can be improved with a tailored developmental program that maximizes the lifetime and fitness of plants. In plant shoots, a developmental phase represents a time window in which the meristem triggers the development of unique morphological and physiological traits, leading to the emergence of leaves, flowers, and fruits. Whereas developmental phases in plant shoots have been shown to enhance food production in crops, this phenomenon has remained poorly investigated in roots. In light of recent advances, we suggest that root development occurs in three main phases: root apical meristem appearance, foraging, and senescence. We provide compelling evidence suggesting that these phases are regulated by at least four developmental pathways: autonomous, non-autonomous, hormonal, and periodic. Root developmental pathways differentially coordinate organ plasticity, promoting morphological alterations, tissue regeneration, and cell death regulation. Furthermore, we suggest how nutritional checkpoints may allow progression through the developmental phases, thus completing the root life cycle. These insights highlight novel and exciting advances in root biology that may help maximize the productivity of crops through more sustainable agriculture and the reduced use of chemical fertilizers.

Evaluated interventions addressing developmental transitions for youth with mental health disorders: a meta-analysis.

PURPOSE: The objective of this meta-analysis was to provide a quantitative synthesis of the effects of studies evaluating developmentally appropriate programs or interventions for transition-age youth with mental health disorders. METHODS: Studies, between January 1992 and March 2021, were included if they contained a sample population with a median age between 12 and 25 years and with a mental health disorder and described the results of health interventions addressing aspects of developmental transitions. Independent reviewers screened study texts and assessed the risk of bias. Random effects meta-analysis was used to pool data on standardized mean differences. RESULTS: Under neurodevelopmental studies (6), the effect size of interventions measuring social outcomes was 1.00 (95% CI: -0.01 to 2.00), parental stress levels was -0.10 (95% CI:-0.74 to 0.55), autism symptoms was -0.40 (95% CI: -1.58 to 0.78), and self-determination was 0.16 (95% CI:-0.38 to 0.70). Under mental illness studies (3), the effect size of interventions measuring adolescent depressive symptoms was 0.48 (95% CI: 0.01 to 0.96) and parental depressive symptoms was 1.09 (95% CI: 0.20 to 1.97). CONCLUSIONS: There is no effect of interventions except on parental depressive symptoms under mental illness studies. Further research with comparable outcomes and assessments is needed.Implications for rehabilitation:Interventions for youth with mental health disorders should be developmentally appropriate and incorporate elements to assist youth in multiple aspects of their lives.The following approaches should be considered in interventions: skills training, prevocational/vocational guidance, a client-centered approach, and/or an ecological/experiential approach.Intervention researchers and practitioners should incorporate similar outcome assessment tools and measures in order to allow for valid comparisons between intervention effectiveness.

The Leishmania donovani LDBPK_220120.1 Gene Encodes for an Atypical Dual Specificity Lipid-Like Phosphatase Expressed in Promastigotes and Amastigotes; Substrate Specificity, Intracellular Localizations, and Putative Role(s).

The intracellular protozoan parasites of the Leishmania genus are responsible for Leishmaniases, vector borne diseases with a wide range of clinical manifestations. Leishmania (L.) donovani causes visceral leishmaniasis (kala azar), the most severe of these diseases. Along their biological cycle, Leishmania parasites undergo distinct developmental transitions including metacyclogenesis and differentiation of metacyclic promastigotes (MPs) to amastigotes. Metacyclogenesis inside the phlebotomine sandfly host's midgut converts the procyclic dividing promastigotes to non-dividing infective MPs eventually injected into the skin of mammalian hosts and phagocytosed by macrophages where the MPs are converted inside modified phagolysosomes to the intracellular amastigotes. These developmental transitions involve dramatic changes in cell size and shape and reformatting of the flagellum requiring thus membrane and cytoskeleton remodeling in which phosphoinositide (PI) signaling and metabolism must play central roles. This study reports on the LDBPK_220120.1 gene, the L. donovani ortholog of LmjF.22.0250 from L. major that encodes a phosphatase from the "Atypical Lipid Phosphatases" (ALPs) enzyme family. We confirmed the expression of the LDBPK_220120.1 gene product in both L. donovani promastigotes and axenic amastigotes and showed that it behaves in vitro as a Dual Specificity P-Tyr and monophosphorylated [PI(3)P and PI(4)P] PI phosphatase and therefore named it LdTyrPIP_22 (Leishmaniad onovani Tyrosine PI Phosphatase, gene locus at chromosome 22). By immunofluorescence confocal microscopy we localized the LdTyrPIP_22 in several intracellular sites in the cell body of L. donovani promastigotes and amastigotes and in the flagellum. A temperature and pH shift from 25°C to 37°C and from pH 7 to 5.5, induced a pronounced recruitment of LdTyrPIP_22 epitopes to the flagellar pocket and a redistribution around the nucleus. These results suggest possible role(s) for this P-Tyr/PI phosphatase in the regulation of processes initiated or upregulated by this temperature/pH shift that contribute to the developmental transition from MPs to amastigotes inside the mammalian host macrophages.

The Cytokinin Status of the Epidermis Regulates Aspects of Vegetative and Reproductive Development in Arabidopsis thaliana.

The epidermal cell layer of plants has important functions in regulating plant growth and development. We have studied the impact of an altered epidermal cytokinin metabolism on Arabidopsis shoot development. Increased epidermal cytokinin synthesis or breakdown was achieved through expression of the cytokinin synthesis gene LOG4 and the cytokinin-degrading CKX1 gene, respectively, under the control of the epidermis-specific AtML1 promoter. During vegetative growth, increased epidermal cytokinin production caused an increased size of the shoot apical meristem and promoted earlier flowering. Leaves became larger and the shoots showed an earlier juvenile-to-adult transition. An increased cytokinin breakdown had the opposite effect on these phenotypic traits indicating that epidermal cytokinin metabolism can be a factor regulating these aspects of shoot development. The phenotypic consequences of abbreviated cytokinin signaling in the epidermis achieved through expression of the ARR1-SRDX repressor were generally milder or even absent indicating that the epidermal cytokinin acts, at least in part, cell non-autonomously. Enhanced epidermal cytokinin synthesis delayed cell differentiation during leaf development leading to an increased cell proliferation and leaf growth. Genetic analysis showed that this cytokinin activity was mediated mainly by the AHK3 receptor and the transcription factor ARR1. We also demonstrate that epidermal cytokinin promotes leaf growth in a largely cell-autonomous fashion. Increased cytokinin synthesis in the outer layer of reproductive tissues and in the placenta enhanced ovule formation by the placenta and caused the formation of larger siliques. This led to a higher number of seeds in larger pods resulting in an increased seed yield per plant. Collectively, the results provide evidence that the cytokinin metabolism in the epidermis is a relevant parameter determining vegetative and reproductive plant growth and development.

Identification and profiling of Bactrocera dorsalis microRNAs and their potential roles in regulating the developmental transitions of egg hatching, molting, pupation and adult eclosion.

MicroRNAs (miRNAs) are endogenous small noncoding RNAs (18-25 nt) that are involved in many physiological processes including development, cancer, immunity, apoptosis and host-microbe interactions through post-transcriptional regulation of gene expression. In this study, we measured the profile of small RNAs over the developmental transitions of the oriental fruit fly Bactrocera dorsalis from egg hatching, molting, and pupation to adult eclosion. We identified 250 miRNAs, including 83 known and 167 novel miRNAs, and 47 isomiRNAs. In addition, we identified the miRNAs differentially expressed over the developmental transitions. Interestingly, the miR-309 cluster, the miR-2 cluster/family and the let-7 cluster were among these differentially expressed miRNAs, suggesting a role in the regulation of egg hatching, molting and pupation/adult eclosion, respectively. Moreover, a detailed analysis of the temporal expression patterns of 14 highly expressed miRNAs in the pupal stage revealed three types of expression profiles. Furthermore, injection of a miR-100 mimic in the 3rd instar larvae resulted in a significant decrease in pupation and adult eclosion rates, whereas injection of a miR-317 antagomir resulted in a significant decrease in the pupation rate and a decrease in the pupation time, indicating that miR-100 and miR-317 are involved in the process of pupation. Finally, injection of a miR-100/miR-285 mimic or antagomir in pupae resulted in a significant decrease in the eclosion rate and a significant increase in the prevalence of a partial eclosion phenotype, implying the involvement of miR-100 and miR-285 in the process of adult eclosion. This study identified critical miRNAs involved in the transitions of this important holometabolic model and pest insect B. dorsalis from egg hatching to adult eclosion, thus providing a useful resource for exploring the regulatory role of miRNAs during insect post-embryonic development.

Size-Regulated Symmetry Breaking in Reaction-Diffusion Models of Developmental Transitions.

The development of multicellular organisms proceeds through a series of morphogenetic and cell-state transitions, transforming homogeneous zygotes into complex adults by a process of self-organisation. Many of these transitions are achieved by spontaneous symmetry breaking mechanisms, allowing cells and tissues to acquire pattern and polarity by virtue of local interactions without an upstream supply of information. The combined work of theory and experiment has elucidated how these systems break symmetry during developmental transitions. Given that such transitions are multiple and their temporal ordering is crucial, an equally important question is how these developmental transitions are coordinated in time. Using a minimal mass-conserved substrate-depletion model for symmetry breaking as our case study, we elucidate mechanisms by which cells and tissues can couple reaction-diffusion-driven symmetry breaking to the timing of developmental transitions, arguing that the dependence of patterning mode on system size may be a generic principle by which developing organisms measure time. By analysing different regimes of our model, simulated on growing domains, we elaborate three distinct behaviours, allowing for clock-, timer- or switch-like dynamics. Relating these behaviours to experimentally documented case studies of developmental timing, we provide a minimal conceptual framework to interrogate how developing organisms coordinate developmental transitions.

Developmental transitions during adulthood and neighborliness: A multilevel cluster analysis.

Neighborliness plays a critical role in promoting social integration, and is known to positively influence health and psychosocial adjustment. We examined variation in neighborliness based on developmental transitions as well as on the neighborhood context. We examined the direct and moderating role of neighborhood factors, to determine whether the neighborhood context modified the influence of developmental transitions on neighborliness. We analyzed data from a longitudinal study of Australian communities, in addition to census data. First, we analyzed developmental transition clusters. Next, we employed multilevel modeling to assess the impact of clusters and other key factors on neighborliness. We tested interactions to determine whether the influence of cluster membership on neighborliness was modified by the neighborhood. We found evidence for direct effects of cluster membership and structural factors on neighborliness. In addition, the neighborhood context modified the influence of cluster membership on neighborliness. Our findings underscore the importance of promoting neighborhood social engagement throughout the life course.

E2FA and E2FB transcription factors coordinate cell proliferation with seed maturation.

The E2F transcription factors and the RETINOBLASTOMA-RELATED repressor protein are principal regulators coordinating cell proliferation with differentiation, but their role during seed development is little understood. We show that in fully developed Arabidopsis thaliana embryos, cell number was not affected either in single or double mutants for the activator-type E2FA and E2FB Accordingly, these E2Fs are only partially required for the expression of cell cycle genes. In contrast, the expression of key seed maturation genes LEAFY COTYLEDON 1/2 (LEC1/2), ABSCISIC ACID INSENSITIVE 3, FUSCA 3 and WRINKLED 1 is upregulated in the e2fab double mutant embryo. In accordance, E2FA directly regulates LEC2, and mutation at the consensus E2F-binding site in the LEC2 promoter de-represses its activity during the proliferative stage of seed development. In addition, the major seed storage reserve proteins, 12S globulin and 2S albumin, became prematurely accumulated at the proliferating phase of seed development in the e2fab double mutant. Our findings reveal a repressor function of the activator E2Fs to restrict the seed maturation programme until the cell proliferation phase is completed.

Linker histones are fine-scale chromatin architects modulating developmental decisions in Arabidopsis.

BACKGROUND: Chromatin provides a tunable platform for gene expression control. Besides the well-studied core nucleosome, H1 linker histones are abundant chromatin components with intrinsic potential to influence chromatin function. Well studied in animals, little is known about the evolution of H1 function in other eukaryotic lineages for instance plants. Notably, in the model plant Arabidopsis, while H1 is known to influence heterochromatin and DNA methylation, its contribution to transcription, molecular, and cytological chromatin organization remains elusive. RESULTS: We provide a multi-scale functional study of Arabidopsis linker histones. We show that H1-deficient plants are viable yet show phenotypes in seed dormancy, flowering time, lateral root, and stomata formation-complemented by either or both of the major variants. H1 depletion also impairs pluripotent callus formation. Fine-scale chromatin analyses combined with transcriptome and nucleosome profiling reveal distinct roles of H1 on hetero- and euchromatin: H1 is necessary to form heterochromatic domains yet dispensable for silencing of most transposable elements; H1 depletion affects nucleosome density distribution and mobility in euchromatin, spatial arrangement of nanodomains, histone acetylation, and methylation. These drastic changes affect moderately the transcription but reveal a subset of H1-sensitive genes. CONCLUSIONS: H1 variants have a profound impact on the molecular and spatial (nuclear) chromatin organization in Arabidopsis with distinct roles in euchromatin and heterochromatin and a dual causality on gene expression. Phenotypical analyses further suggest the novel possibility that H1-mediated chromatin organization may contribute to the epigenetic control of developmental and cellular transitions.

On the role of mindfulness and compassion skills in students' coping, well-being, and development across the transition to college: A conceptual analysis.

In this paper, we aim to integrate the current conceptual approaches to stress and coping processes during the college transition with the potential role of mindfulness and compassion (MC) skills on students' well-being and development. First, we provide an overview of the issues and challenges emerging adults are facing during the transition to college, drawing on the revised version of the transactional stress model by Lazarus and Folkman (1984). Second, we introduce a conceptual model of adaptive stress and coping processes enhanced by MC skills to positively impact the appraisal and coping resources and emerging adults' mental health. Specifically, MC skills may play an important role in promoting a healthy stress response by strengthening emerging adults' socioemotional competencies and supporting the development of adaptive appraisal and coping resources, including processes antecedent and consequent to a coping encounter. In particular, MC skills were hypothesized to enhance (a) preparedness to cope, (b) productive stress response through adaptive appraisals and skillful deployment of coping resources, and (c) healthy postcoping reflections. Therefore, MC skills may be a useful preventive tool to strengthen emerging adults' ability to adjust to a new academic environment and fulfil the developmental tasks of this period.

A role for Lin-28 in growth and metamorphosis in Drosophila melanogaster.

Insect metamorphosis has been a classic model to understand the role of hormones in growth and timing of developmental transitions. In addition to hormones, transitions in some species are regulated by genetic programs, such as the heterochronic gene network discovered in C. elegans. However, the functional link between hormones and heterochronic genes is not clear. The heterochronic gene lin-28 is involved in the maintenance of stem cells, growth and developmental timing in vertebrates. In this work, we used gain-of-function and loss-of-function experiments to study the role of Lin-28 in larval growth and the timing of metamorphosis of Drosophila melanogaster. During the late third instar stage, Lin-28 is mainly expressed in neurons of the central nervous system and in the intestine. Loss-of-function lin-28 mutant larvae are smaller and the larval-to-pupal transition is accelerated. This faster transition correlates with increased levels of ecdysone direct target genes such as Broad-Complex (BR-C) and Ecdysone Receptor (EcR). Overexpression of Lin-28 does not affect the timing of pupariation but most animals are not able to eclose, suggesting defects in metamorphosis. Overexpression of human Lin-28 results in delayed pupariation and the death of animals during metamorphosis. Altogether, these results suggest that Lin-28 is involved in the control of growth during larval development and in the timing and progression of metamorphosis.

Launching Anxious Young Adults: A Specialized Cognitive-Behavioral Intervention for Transitional Aged Youth.

PURPOSE OF REVIEW: There has been growing clinical and research attention to the unique developmental stage of emerging adulthood. This stage is a time of significant change and growth for all individuals, as it includes identity exploration, emotional, behavioral, and financial independence from caregivers, and completion of educational or vocational requirements. RECENT FINDINGS: Anxiety disorders are the most common mental health diagnoses among emerging adults, and individuals suffering from these disorders often experience compounding functional impairments across health, financial, and social domains. While evidence-based treatments exist for both child/adolescent anxiety disorders and adult anxiety disorders, no specialized assessment or treatment methods have been established for the unique period of emerging adulthood. Our review examines literature pertinent to anxiety disorders in emerging adulthood and describes a novel, specialized intervention to address the unique challenges faced by anxious emerging adults. The Launching Emerging Adults Program (LEAP) is a developmentally informed cognitive-behavioral treatment model that aims to simultaneously reduce anxiety symptoms and promote independence. We conclude with a discussion of lessons learned and future directions.

Age Differences in Age Perceptions and Developmental Transitions.

Is 50 considered "old"? When do we stop being considered "young"? If individuals could choose to be any age, what would it be? In a sample of 502,548 internet respondents ranging in age from 10 to 89, we examined age differences in aging perceptions (e.g., how old do you feel?) and estimates of the timing of developmental transitions (e.g., when does someone become an older adult?). We found that older adults reported older perceptions of aging (e.g., choosing to be older, feeling older, being perceived as older), but that these perceptions were increasingly younger than their current age. The age to which individuals hope to live dramatically increased after age 40. We also found that older adults placed the age at which developmental transitions occurred later in the life course. This latter effect was stronger for transitions involving middle-age and older adulthood compared to transitions involving young adulthood. The current study constitutes the largest study to date of age differences in age perceptions and developmental timing estimates and yielded novel insights into how the aging process may affect judgments about the self and others.

Genetic Regulation of the 2D to 3D Growth Transition in the Moss Physcomitrella patens.

One of the most important events in the history of life on earth was the colonization of land by plants; this transition coincided with and was most likely enabled by the evolution of 3-dimensional (3D) growth. Today, the diverse morphologies exhibited across the terrestrial biosphere arise from the differential regulation of 3D growth processes during development. In many plants, 3D growth is initiated during the first few divisions of the zygote, and therefore, the genetic basis cannot be dissected because mutants do not survive. However, in mosses, which are representatives of the earliest land plants, 3D shoot growth is preceded by a 2D filamentous phase that can be maintained indefinitely. Here, we used the moss Physcomitrella patens to identify genetic regulators of the 2D to 3D transition. Mutant screens yielded individuals that could only grow in 2D, and through an innovative strategy that combined somatic hybridization with bulk segregant analysis and genome sequencing, the causative mutation was identified in one of them. The NO GAMETOPHORES 1 (NOG1) gene, which encodes a ubiquitin-associated protein, is present only in land plant genomes. In mutants that lack PpNOG1 function, transcripts encoding 3D-promoting PpAPB transcription factors [1] are significantly reduced, and apical initial cells specified for 3D growth are not formed. PpNOG1 acts at the earliest identified stage of the 2D to 3D transition, possibly through degradation of proteins that suppress 3D growth. The acquisition of NOG1 function in land plants could thus have enabled the evolution and development of 3D morphology.