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.

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.

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 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.

Lonely at the top? Regulation of shoot apical meristem activity by intrinsic and extrinsic factors

All the above-ground organs of a plant are derived from stem cells that reside in shoot apical meristems (SAM). Over the past 25 years, the genetic pathways that control the proliferation of stem cells within the SAM, and the differentiation of their progenitors into lateral organs, have been described in great detail. However, longstanding questions regarding the importance of communication between cells within the SAM and lateral organs have, until recently, remained unanswered. In this review, we describe recent investigations into the extent, nature and significance of signaling both to and from the SAM.

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.

Sexual victimization histories and substance use trajectories during the transition out of college

The college years are a period of peak vulnerability for sexual victimization (SV) and substance misuse. During college, students with SV histories report riskier substance use patterns, yet little is known about the influence of SV on substance use behaviors as students begin to transition away from the college environment. This was the purpose of the present study. College seniors (N = 480; 61% female) reported on their alcohol and drug use behaviors across 5 time points spanning 1 calendar year. For many, this year included the transition out of college. Latent growth curve analysis was used to determine whether trajectories for alcohol and drug use as well as alcohol and drug consequences differed based on SV histories (no SV, precollege SV, college SV, precollege + college SV). Results revealed that at the start of senior year, young adults with SV histories reported greater substance use and consequences relative to nonvictimized peers. Over the year, SV histories were associated with steeper declines in substance use and consequences. Despite the declines, those who were revictimized across developmental time periods (precollege + college SV) consistently reported higher alcohol use and consequences across the transitional year, although this did not replicate for other drugs. In sum, although alcohol and other drug involvement among those with SV histories decreased over time, precollege + college SV histories continued to be a persistent risk factor for heavier alcohol use behaviors. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

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.

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NO GAMETOPHORES 1 (PpNOG1) regulates the 2D to 3D growth transition in P. patens

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PpNOG1 acts upstream of 3D-promoting PpAPB transcription factors

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PpNOG1 is required for the formation of apical initial cells specified for 3D growth

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NOG1 genes are found only in land plants and thus evolved coincident with 3D growth

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.

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.

Developmental transitions in Arabidopsis are regulated by antisense RNAs resulting from bidirectionally transcribed genes

Transcription terminators are DNA elements located at the 3' end of genes that ensure efficient cleavage of nascent RNA generating the 3' end of mRNA, as well as facilitating disengagement of elongating DNA-dependent RNA polymerase II. Surprisingly, terminators are also a potent source of antisense transcription. We have recently described an Arabidopsis antisense transcript originating from the 3' end of a master regulator of Arabidopsis thaliana seed dormancy DOG1. In this review, we discuss the broader implications of our discovery in light of recent developments in yeast and Arabidopsis. We show that, surprisingly, the key features of terminators that give rise to antisense transcription are preserved between Arabidopsis and yeast, suggesting a conserved mechanism. We also compare our discovery to known antisense-based regulatory mechanisms, highlighting the link between antisense-based gene expression regulation and major developmental transitions in plants.

A scoping review of evaluated interventions addressing developmental transitions for youth with mental health disorders

BACKGROUND

Youth with mental health disorders often experience challenges when transitioning into adult roles (e.g. independent living, work and community engagement). Health interventions that address the needs of youth with mental health disorders during these challenges in their development (i.e. developmental transitions) have not been reviewed in the literature. This scoping review examines the peer-reviewed research that describes evaluated interventions addressing developmental transitions for youth with mental health disorders.

METHODS

A search of four prominent health literature databases (CINAHL, Embase, MEDLINE and PsycINFO) was conducted to identify evaluated developmental transition interventions for adolescents and youth (12-25 years) with mental health disorders. Study selection and analysis were guided by a methodological framework for conducting scoping reviews. Selected studies were described, assessed for quality and collated based on ten dimensions from two notable conceptual frameworks in developmental transitions and disability.

RESULTS

Nine studies met the inclusion criteria. The interventions within these studies demonstrated five specialized and four multi-faceted programmes (i.e. multiple domains). All domains from the two conceptual frameworks were represented differently across studies. The sub-domains from these studies were most frequently related to vocational-focused interventions, least frequently related to social activities and living situation and did not explicitly map onto the sexuality sub-domain. Three multi-faceted interventions incorporated all domains and utilized each intervention approach. Study quality was rated for seven of the nine studies. Quantitative methodology for five of the seven studies was rated as higher quality.

CONCLUSIONS

Evaluated interventions described in the transitions literature for youth with mental health disorders predominantly focus on vocational needs. The least studied areas were the personal and interpersonal domains. These domains were only incorporated within interventions addressing multiple domains of developmental transitions. These insights can be helpful in guiding evidence-based practice and policy development, as well as informing gaps for future research programmes.

Functional Evolution in the Plant SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) Gene Family

The SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) family of transcription factors is functionally diverse, controlling a number of fundamental aspects of plant growth and development, including vegetative phase change, flowering time, branching, and leaf initiation rate. In natural plant populations, variation in flowering time and shoot architecture have major consequences for fitness. Likewise, in crop species, variation in branching and developmental rate impact biomass and yield. Thus, studies aimed at dissecting how the various functions are partitioned among different SPL genes in diverse plant lineages are key to providing insight into the genetic basis of local adaptation and have already garnered attention by crop breeders. Here we use phylogenetic reconstruction to reveal nine major SPL gene lineages, each of which is described in terms of function and diversification. To assess evidence for ancestral and derived functions within each SPL gene lineage, we use ancestral character state reconstructions. Our analyses suggest an emerging pattern of sub-functionalization, neo-functionalization, and possible convergent evolution following both ancient and recent gene duplication. Based on these analyses we suggest future avenues of research that may prove fruitful for elucidating the importance of SPL gene evolution in plant growth and development.

The role of age and social motivation in developmental transitions in young and old adulthood

Two diary studies investigated the role of social approach and avoidance motivation in important developmental transitions in young and old adulthood. Study 1 comprised a sample of young adults (N = 93, M = 21.5 years) who moved out of their parental homes. The sample of Study 2 consisted of older adults (N = 69, M = 76.95 years) who moved into senior housing. In both studies, participants reported their habitual social approach and avoidance motives as well as their daily social experience and subjective well-being over the course of 2 weeks. In line with the literature, social approach motives and age were related to higher subjective well-being, whereas social avoidance motives were negatively associated with subjective well-being. Time since the transition was an important moderator of the association between social avoidance motives and negative outcomes. With increasing time from the transition, the negative effects of social avoidance motives decreased. The positive effects of social approach motives remained fairly stable over time. Importantly, age did not moderate any of the associations between social motivation and outcomes. Results are discussed in terms of transition-related instability and age-related stability.

Behavioral risks during the transition from high school to college

The transition from high school to college is an important developmental milestone that holds the potential for personal growth and behavioral change. A cohort of 2,245 students was recruited during the summer before they matriculated into college and completed Internet-based surveys about their participation in a variety of behavioral risks during the last 3 months of high school and throughout the 1st year of college. Alcohol use, marijuana use, and sex with multiple partners increased during the transition from high school to college, whereas driving after drinking, aggression, and property crimes decreased. Those from rural high schools and those who elected to live in private dormitories in college were at highest risk for heavy drinking and driving after drinking.