Developmental Changes Research Articles

노년의 지능과 창의력의 변화

This study explored the developmental changes of intelligence and creativity in ageing process of the late adulthood. The intelligence declined generally in ageing once subjects passed the age of around sixty or more, but the pattern of its changes was differential. Fluid intelligence could be surely affected by ageing and the basic reflex skills such as the response time and response accuracy deteriorated steadily. But crystallized intelligence, which had been based on the pre-learned knowledge, could be relatively fixed and so unaffected by the ageing process and, further, it could compensate for some of the effects of fluid intelligence loss. These group data on intellectual skills decline might not be uniformly true of all ageing people and inter-individual variability increased significantly with age. There were two theoretical models explaining the aging-related changes of creative thought. The peak and decline model insisted that there should be creativity peak at the age of around 30 - 40 and thereafter creativity declined. But the life-span developmental model of creativity proposed that creativity would reveal no decline, though the creative activities could be decreased. With development of an old age style of dialectical mode, the creativity of the aged people were seemed to evolve to be more incremental than revolutionary and to be more experimental than conceptual. Finally the study noted several implications of the ageing studies employing subjects of the young-olds.

Neural correlates of lexical-tone and vowel-quality processing in 6- and 9-month-old German-learning infants and adults.

We examined the neurophysiological underpinnings of lexical-tone and vowel-quality perception in learners of a non-tonal language. We tested 25 6- and 25 9-month-old German-learning infants, as well as 24 German adults and expected developmental differences for the two linguistic properties, as they are both carried by vowels, but have a different status in German. In adults, both lexical-tone and vowel-quality contrasts elicited mismatch negativities, with a stronger response to the vowel-quality contrast. Six-month-olds showed positive mismatch responses for lexical-tone and vowel-quality contrasts, with an emerging negative mismatch response for vowel-quality only. The negative mismatch responses became more pronounced for the vowel-quality contrast at 9 months, while the lexical-tone contrast elicited mainly positive mismatch responses. Our data reveal differential developmental changes in the processing of vowel properties that differ in their lexical relevance in the ambient language.

The role of intrinsic reward in adolescent word learning.

Relatively little work has focused on why we are motivated to learn words. In adults, recent experiments have shown that intrinsic reward signals accompany successful word learning from context. In addition, the experience of reward facilitated long-term memory for words. In adolescence, developmental changes are seen in reward and motivation systems as well as in reading and language systems. Here, in the face of this developmental change, we ask whether adolescents experience reward from word learning, and how the reward and memory benefit seen in adults is modulated by age. We used a naturalistic reading paradigm, which involved extracting novel word meanings from sentence context without the need for explicit feedback. By exploring ratings of enjoyment during the learning phase, as well as recognition memory for words a day later, we assessed whether adolescents show the same reward and learning patterns as adults. We tested 345 children between the ages of 10-18 (N>84 in each 2-year age-band) using this paradigm. We found evidence for our first prediction: children aged 10-18 report greater enjoyment for successful word learning. However, we did not find evidence for age-related change in this developmental period, or memory benefits. This work gives us greater insight into the process of language acquisition and sets the stage for further investigations of intrinsic reward in typical and atypical development. RESEARCH HIGHLIGHTS: We constantly learn words from context, even in the absence of explicit rewards or feedback. In adults, intrinsic reward experienced during word learning is linked to a dopaminergic circuit in the brain, which also fuels enhancements in memory for words. We find adolescents also report enhanced reward or enjoyment when they successfully learn words from sentence context. The relationship between reward and learning is maintained between the ages of 10 and 18. Unlike in adults, we did not observe ensuing memory benefits.

Developmental differences in children and adults' enforcement of explore versus exploit search strategies in the United States and Turkey.

Across development, as children acquire a deeper understanding of their environment, they explore less and take advantage, or "exploit," what they already know. Here, we test whether children also enforce exploration-oriented search behaviors onto others. Specifically, we ask whether children are more likely to encourage a search agent to explore versus exploit their environment, and whether this pattern varies across childhood (between 3 and 6 years). We also ask whether this pattern differs between children and adults, and generalizes across two different sociocultural contexts-Turkey and the United States-that differ on dimensions that might relate to children's decisions about exploration (e.g., curiosity-focused educational practices, attitudes toward uncertainty avoidance). Participants (N=358) watched an agent search for rewards and were asked at various points whether the agent should "stay" (exploit) in their current location, or "go" (explore) to a new location. At all points in the experiment, children enforced exploration significantly more often than adults. Early in the agent's search, children in the US enforced exploration more often than children in Turkey; later in the search, younger children (from both sociocultural contexts) were more likely to continue enforcing exploration compared to older children. These findings highlight that children are not only highly exploratory themselves, but also enforce exploration onto others-underscoring the central role that exploration plays in driving early cognitive development across diverse sociocultural contexts. RESEARCH HIGHLIGHTS: The current study examined developmental and cross-cultural differences in children and adults' enforcement of explore-exploit search strategies. Children in the US and Turkey enforced exploration more than adults, who enforced exploitation more often; results were generally consistent across cultures with small differences. Mirroring developmental changes in children's own search behavior; the tendency to enforce exploration decreased between 3- to 6-years of age. Findings underscore the central role of an "exploration mindset" in children's early decision-making-even when exploration has no direct benefits to the child themselves.

Location analysis of presynaptically active and silent synapses in single-cultured hippocampal neurons.

A morphologically present but non-functioning synapse is termed a silent synapse. Silent synapses are categorized into "postsynaptically silent synapses," where AMPA receptors are either absent or non-functional, and "presynaptically silent synapses," where neurotransmitters cannot be released from nerve terminals. The presence of presynaptically silent synapses remains enigmatic, and their physiological significance is highly intriguing. In this study, we examined the distribution and developmental changes of presynaptically active and silent synapses in individual neurons. Our findings show a gradual increase in the number of excitatory synapses, along with a corresponding decrease in the percentage of presynaptically silent synapses during neuronal development. To pinpoint the distribution of presynaptically active and silent synapses, i.e., their positional information, we employed Sholl analysis. Our results indicate that the distribution of presynaptically silent synapses within a single neuron does not exhibit a distinct pattern during synapse development in different distance from the cell body. However, irrespective of neuronal development, the proportion of presynaptically silent synapses tends to rise as the projection site moves farther from the cell body, suggesting that synapses near the cell body may exhibit higher synaptic transmission efficiency. This study represents the first observation of changes in the distribution of presynaptically active and silent synapses within a single neuron.

ULTRAPETALA 1 regulates the growth and development of rice plants to promote resilience to salinity stress

Rice, one of the most important agronomically crops, when challenged by high salinity affects its growth at the seedling stage and reproductive phase. Thus, investigating the intricate molecular mechanisms that regulate its developmental process throughout its life cycle is essential for better stress resilience. We have investigated the role of rice trithorax group factor ULTRAPETALA1 (OsULT1) that orchestrates rice development and stress response. A genome-wide chromatin immunoprecipitation analysis revealed OsULT1 enrichment at transcription regulators, oxidative stress signaling, ROS scavengers, and K+ uptake transporters, during salinity stress. Interestingly, loci associated with root development, plant height, inflorescence development, panicles, spikelet numbers, and seed development showed OsULT1 occupancy under control and salt stress. Expression of these genes was regulated by chromatin modifications such as H3K4me3 and H3K27me3. Further, DNA binding analysis showed OsULT1 binding at AP2/ERF core motif A/GCCGAC during salinity stress. OsULT1 overexpression causes developmental changes with enhanced plant height, increase in basal internode length, robust root architecture, and increase in tiller and panicle numbers. Moreover, OsULT1OE showed salinity tolerance with enhanced seed germination, reduced ROS content, low Na+/K+ ratio in shoot and root tissue, and improved post-stress recovery. Collectively, our results indicate that ULT1 regulates different plant developmental pathways for better protection and adaptation against environmental stress.

The influence of anterior cingulateGABA+ and glutamateon emotion regulation and reactivity in adolescents and adults.

During adolescence, emotion regulation and reactivity are still developing and are in many ways qualitatively different from adulthood. However, the neurobiological processes underpinning these differences remain poorly understood, including the role of maturing neurotransmitter systems. We combined magnetic resonance spectroscopy in the dorsal anterior cingulate cortex (dACC) and self-reported emotion regulation and reactivity in a sample of typically developed adolescents (n=37; 13-16 years) and adults (n=39; 30-40 years), and found that adolescents had higher levels of glutamate to total creatine (tCr) ratio in the dACC than adults. A glutamate Í age group interaction indicated a differential relation between dACC glutamate levels and emotion regulation in adolescents and adults, and within-group follow-up analyses showed that higher levels of glutamate/tCr were related to worse emotion regulation skills in adolescents. We found no age-group differences in gamma-aminobutyric acid+macromolecules (GABA+) levels; however, emotion reactivity was positively related to GABA+/tCr in the adult group, but not in the adolescent group. The results demonstrate that there are developmental changes in the concentration of glutamate, but not GABA+, within the dACC from adolescence to adulthood, in accordance with previous findings indicating earlier maturation of the GABA-ergic than the glutamatergic system. Functionally, glutamate and GABA+ are positively related to emotion regulation and reactivity, respectively, in the mature brain. In the adolescent brain, however, glutamate is negatively related to emotion regulation, and GABA+ is not related to emotion reactivity. The findings are consistent with synaptic pruning of glutamatergic synapses from adolescence to adulthood and highlight the importance of brain maturational processes underlying age-related differences in emotion processing.

Developmental trajectory of social reward motivation from early adolescence into adulthood in female and male Long-Evans rats.

Most studies of adolescent and adult behavior involved one age group of each, whereas the dynamic changes in brain development suggest that there may be behavioral flux in adolescence. In two studies, we investigated developmental changes in social reward motivation in female and male Long-Evans rats from prepuberty to early adulthood in a social operant conditioning task. Given the earlier onset of puberty in females than in males, we predicted the course of social reward development would differ between the sexes. Overall, the pattern of results from both studies suggests that the trajectory of social motivation across adolescence is characterized by upward and downward shifts that do not depend on the sex of the rats. During training, in both studies, the mean number of social gate openings and percentage of social gate openings was higher at P30 (prepubertal, early adolescence) and P50 (late adolescence) than at P40 (mid adolescence) and P70 (adulthood) irrespective of sex. Nevertheless, the specific age comparisons that were significant depended on the study. In both studies, P30 rats had greater levels of social motivation than did adults in accessing a social reward when increased effort was required (progressive ratio tests). In an extinction test, only P30 and P50 rats continued to show more nose-pokes at the previously social gate than at the nonsocial gate, suggesting resistance to extinction. The results highlight the importance of characterizing behavior at several timepoints in adolescence to understand the neural mechanisms, many of which show similar discontinuities as they develop across adolescence.

Pre-eclamptic foetal programming predisposes offspring to hepatic steatosis via DNA methylation

ObjectivesGamete and embryo–foetal origins of adult diseases hypothesis proposes that adulthood chronic disorders are associated with adverse foetal and early life traits. Our study aimed to characterise developmental changes and underlying mechanisms of metabolic disorders in offspring of pre-eclampsia (PE) programmed pregnancy. MethodsNω-Nitro-l-arginine methyl ester hydrochloride (L-NAME) induced pre-eclampsia-like C57BL/6J mouse model was used. Lipid profiling, histological morphology, indirect calorimetry, mRNA sequencing, and pyrosequencing were performed on PE offspring of both young and elderly ages. ResultsPE offspring exhibited increased postnatal weight gain, hepatic lipid accumulation, enlarged adipocytes, and impaired energy balance that continued to adulthood. Integrated RNA sequencing of foetal and 52-week-old livers revealed that the differentially expressed genes were mainly enriched in lipid metabolism, including glycerol-3-phosphate acyl-transferase 3 (Gpat3), a key enzyme for de novo synthesis of triglycerides (TG), and carnitine palmitoyltransferase-1a (Cpt1a), a key transmembrane enzyme that mediates fatty acid degradation. Pyrosequencing of livers from PE offspring identified hypomethylated and hypermethylated regions in Gpat3 and Cpt1a promoters, which were associated with upregulated and downregulated expressions of Gpat3 and Cpt1a, respectively. These epigenetic alterations are persistent and consistent from the foetal stage to adulthood in PE offspring. ConclusionThese findings suggest a methylation-mediated epigenetic mechanism for PE-induced intergenerational lipid accumulation, impaired energy balance and obesity in offspring, and indicate the potential benefits of early interventions in offspring exposed to maternal PE to reduce their susceptibility to metabolic disorder in their later life.

Redox regulation of epigenetic and epitranscriptomic gene regulatory pathways in plants.

Developmental and environmental constraints influence genome expression through complex networks of regulatory mechanisms. Epigenetic modifications and remodelling of chromatin are some of the major actors regulating the dynamic of gene expression. Unravelling the factors relaying environmental signals that induce gene expression reprogramming under stress conditions is an important and fundamental question. Indeed, many enzymes involved in epigenetic and chromatin modifications are regulated by redox pathways, through post-translational modifications of proteins or by modifications of the flux of metabolic intermediates. Such modifications are potential hubs to relay developmental and environmental changes for gene expression reprogramming. In this review, we provide an update on the interaction between major redox mediators, such as reactive oxygen and nitrogen species and antioxidants, and epigenetic changes in plants. We detail how redox status alters post-translational modifications of proteins, intracellular epigenetic and epitranscriptional modifications, and how redox regulation interplays with DNA methylation, histone acetylation and methylation, miRNA biogenesis, and chromatin structure and remodelling to reprogram genome expression under environmental constraints.

EXPRESS: The Development of Lexical Processing: Real-Time Phonological Competition and Semantic Activation in School Age Children.

Prior research suggests that real-time phonological competition processes are stabilized in early childhood (Fernald et al., 2006). However, recent work suggests that development of these processes continues throughout adolescence (Huang & Snedeker, 2011; Rigler et al., 2015). This study aimed to investigate whether these developmental changes are based solely within the lexical system or are due to domain general changes. This study also aimed to investigate the development of real-time lexical-semantic activation. We captured semantic activation phonological competition and non-linguistic domain general processing skills using two Visual World Paradigm experiments in 43 7-9-year-olds, 42 10-13-year-olds, and 30 16-17-year-olds. Older children were quicker to fixate the target word and exhibited earlier onset and offset of fixations to both semantic and phonological competitors. Visual/cognitive skills explained significant, but not all, variance in the development of these effects. Developmental changes in semantic activation were largely attributable to changes in phonological processing. These results suggest that the concurrent development of linguistic processes and broader visual/cognitive skills lead to developmental changes in real-time phonological competition, while semantic activation is stable across these ages.

Gender diversity among adolescents with obesity in a weight management programme.

Gender dysphoria (GD) and obesity share commonalities, including associations with mental health comorbidities, disordered eating, body dissatisfaction and may intensify with physical and developmental changes during adolescence. While associations of obesity and gender diversity have been identified, rates of gender diversity among adolescents with obesity remain unclear. The aim was to examine gender diversity among adolescents with obesity in a weight management programme. A single-centre cross-sectional questionnaire study was conducted. Eligible adolescents received the Gender Identity/GD Questionnaire for Adolescents and Adults (GIDYQ-AA), a validated instrument measuring gender diversity and GD. Gender identities, sexual orientations, questionnaire scores, and frequency of GD (GIDYQ-AA score <3) were determined. The relationship of GIDYQ-AA scores and BMI Z-score (BMIz) was assessed. Of 72 consenting youth, 29 assigned females (AF) and 17 assigned males (AM) completed GIDYQ-AA and demographic questions. Seventeen (59%) AF reported non-heterosexual orientations, and 6 (21%) reported non-cisgender identities. One (6%) AM reported non-cisgender identity. Two (4%) AF individuals had GD based on GIDYQ-AA scores. GIDYQ-AA scores did not correlate with BMIz. In conclusion, adolescents with obesity, particularly AF with non-heterosexual orientation, reported high rates of non-cisgender identity and GD. Routine screening for gender-related concerns in weight management settings may be warranted.

Human Brain Magnetic Resonance Imaging Studies for Psychiatric Disorders: The Current Progress and Future Directions.

With the prevalence of psychiatric disorders and the limitations of the diagnostic scheme and treatment options of these disorders, magnetic resonance imaging (MRI) studies play a significant role in uncovering the pathological basis of psychiatric disorders and potentially using biological markers in clinical settings. The use of MRI in clinical research has grown over the past three decades, and current MRI research continues to provide an avenue to guide the development of diagnostic approaches and therapeutic solutions. However, the current shortcomings of MRI studies derive not only from technical limitations (i.e., the range of contrasts that MRI probes or sensors can create) but also from confounding factors in the current methodological approaches of case-control studies for psychiatric disorders. Thus, by reviewing the recent literature on MRI research on psychiatric disorders, we explain the current progress and limitations of brain MRI methodologies used to study psychiatric disorders. We consider the growing use of cross-disorder methods to identify shared and disease-specific pathological features across psychiatric disorders. In addition, we need to outline healthy developmental and aging changes of the brain and investigate the disorder difference as a deviation of the trajectory. Although these methods have provided us with new insights, the demarcation between psychiatric disorders based on a definitive set of pathologies remains limited. This challenge of disease stratification is further complicated by the presence of multiple different sets of disorder pathologies within a single disorder and the different progressive timelines of different disorders. As such, we introduce the ongoing research projects in Japan, namely, the Brain Mapping by Integrated Neurotechnologies for Disease Studies (Brain/MINDS) and the Strategic International Brain Science Research Promotion Program (Brain/MINDS Beyond). These collaborative research initiatives across Japan use neuroimaging and travel-subject harmonization to conduct nationwide MRI studies capable of providing large-scale coherent results, which may address the current limitations of MRI psychiatric disorder research.

Postnatal Development of Synaptic Plasticity at Hippocampal CA1 Synapses: Correlation of Learning Performance with Pathway-Specific Plasticity.

To determine the critical timing for learning and the associated synaptic plasticity, we analyzed developmental changes in learning together with training-induced plasticity. Rats were subjected to an inhibitory avoidance (IA) task prior to weaning. While IA training did not alter latency at postnatal day (PN) 16, there was a significant increase in latency from PN 17, indicating a critical day for IA learning between PN 16 and 17. One hour after training, acute hippocampal slices were prepared for whole-cell patch clamp analysis following the retrieval test. In the presence of tetrodotoxin (0.5 µM), miniature excitatory postsynaptic currents (mEPSCs) and inhibitory postsynaptic currents (mIPSCs) were sequentially recorded from the same CA1 neuron. Although no changes in the amplitude of mEPSCs or mIPSCs were observed at PN 16 and 21, significant increases in both excitatory and inhibitory currents were observed at PN 23, suggesting a specific critical day for training-induced plasticity between PN 21 and 23. Training also increased the diversity of postsynaptic currents at PN 23 but not at PN 16 and 21, demonstrating a critical day for training-induced increase in the information entropy of CA1 neurons. Finally, we analyzed the plasticity at entorhinal cortex layer III (ECIII)-CA1 or CA3-CA1 synapses for each individual rat. At either ECIII-CA1 or CA3-CA1 synapses, a significant correlation between mean α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid/N-methyl-D-aspartic acid (AMPA/NMDA) ratio and learning outcomes emerged at PN 23 at both synapses, demonstrating a critical timing for the direct link between AMPA receptor-mediated synaptic plasticity and learning efficacy. Here, we identified multiple critical periods with respect to training-induced synaptic plasticity and delineated developmental trajectories of learning mechanisms at hippocampal CA1 synapses.

How maternal and paternal parenting behaviors predict developmental changes in self-control and deviance during early adolescence

PurposeThe present study tested the pattern of developmental changes in self-control during early adolescence, and whether maternal and paternal closeness, support, monitoring, and disciplinary inconsistency were associated with developmental changes in deviance, indirectly through developmental changes in self-control. MethodsFive assessments part of the Brno Longitudinal Study of Youth on 582 early adolescents (58.4% female; Mage = 12.34 years, SD = 0.89 at baseline) were used for the study. A latent growth model tested the growth of self-control over two years in early adolescence. Associations between parenting and developmental changes in self-control as well as deviance were tested using structural equation modeling with latent constructs. ResultsSelf-control declined over time; individuals varied both in initial levels and rates of change. Full mediation through developmental changes in self-control were found; more specifically, more maternal monitoring at age 12 was associated with increases in self-control at age 13, which, in turn, was associated with less deviance at age 14. Results also provided evidence of direct effects, where more maternal closeness at age 12 was associated with less deviance at age 14. ConclusionsSelf-control decreased during early adolescence, thus supporting continued malleability. Both maternal closeness and monitoring were associated with less deviance, where the effect of monitoring was mediated through self-control.

Trajectories of digital flourishing in adolescence: The predictive roles of developmental changes and digital divide factors.

Digital flourishing refers to the positive perceptions of digital communication use in five dimensions: connectedness, positive social comparison, authentic self-presentation, civil participation, and self-control. This three-wave panel study among 1081 Slovenian adolescents (Mage = 15.34 years, 53.8% boys, 80.7% ethnic majority) explored the trajectories of their digital flourishing dimensions over 1 year (2021-2022). Latent class growth analysis identified two classes. Adolescents in the first class reported high levels of digital flourishing, which remained stable over time, whereas those in the second class reported low levels of digital flourishing with decreased self-control over time. Autonomy-supportive restrictive, autonomy-supportive active, and controlling active parental mediation styles, together with high parental digital skills, predicted adolescents' belongingness to the (more digitally flourishing) first class.

The Role of Sleep for Age-Related Differences in Neurobehavioral Performance.

This study investigated developmental changes from childhood to adulthood in neurobehavioral performance and sleep measures. While many studies have examined age-related changes between childhood and adolescence and from mid-to-late adulthood, young adulthood has been overlooked. The main aim of this study was to investigate the effects of sleep loss on developmental changes in neurobehavioral performance and sleepiness in a natural setting. A total of 119 children, adolescents, and young adults (38 children aged 6-9; 38 adolescents aged 13-19; and 43 young adults aged 20-27) wore an actigraph for a continuous five-weekday night. Subjective sleepiness (Karolinska Sleepiness Scale) and neurobehavioral performance (using the psychomotor vigilance test and the digit symbol substitution test) were measured on five school days. The results showed that adolescents and young adults outperformed children on both the digit symbol substitution test and the psychomotor vigilance test measures. However, adolescents committed more errors of commission on the psychomotor vigilance test and reported higher levels of subjective sleepiness. The results are discussed in relation to brain maturation in various cognitive functions.

Fossil-calibrated molecular clock data enable reconstruction of steps leading to differentiated multicellularity and anisogamy in the Volvocine algae.

Throughout its nearly four-billion-year history, life has undergone evolutionary transitions in which simpler subunits have become integrated to form a more complex whole. Many of these transitions opened the door to innovations that resulted in increased biodiversity and/or organismal efficiency. The evolution of multicellularity from unicellular forms represents one such transition, one that paved the way for cellular differentiation, including differentiation of male and female gametes. A useful model for studying the evolution of multicellularity and cellular differentiation is the volvocine algae, a clade of freshwater green algae whose members range from unicellular to colonial, from undifferentiated to completely differentiated, and whose gamete types can be isogamous, anisogamous, or oogamous. To better understand how multicellularity, differentiation, and gametes evolved in this group, we used comparative genomics and fossil data to establish a geologically calibrated roadmap of when these innovations occurred. Our ancestral-state reconstructions, show that multicellularity arose independently twice in the volvocine algae. Our chronograms indicate multicellularity evolved during the Carboniferous-Triassic periods in Goniaceae + Volvocaceae, and possibly as early as the Cretaceous in Tetrabaenaceae. Using divergence time estimates we inferred when, and in what order, specific developmental changes occurred that led to differentiated multicellularity and oogamy. We find that in the volvocine algae the temporal sequence of developmental changes leading to differentiated multicellularity is much as proposed by David Kirk, and that multicellularity is correlated with the acquisition of anisogamy and oogamy. Lastly, morphological, molecular, and divergence time data suggest the possibility of cryptic species in Tetrabaenaceae. Large molecular datasets and robust phylogenetic methods are bringing the evolutionary history of the volvocine algae more sharply into focus. Mounting evidence suggests that extant species in this group are the result of two independent origins of multicellularity and multiple independent origins of cell differentiation. Also, the origin of the Tetrabaenaceae-Goniaceae-Volvocaceae clade may be much older than previously thought. Finally, the possibility of cryptic species in the Tetrabaenaceae provides an exciting opportunity to study the recent divergence of lineages adapted to live in very different thermal environments.

Developmental changes in nuclear lamina components during germ cell differentiation

ABSTRACT The nuclear lamina (NL) changes composition for regulation of nuclear events. We investigated changes that occur in Drosophila oogenesis, revealing switches in NL composition during germ cell differentiation. Germline stem cells (GSCs) express only LamB and predominantly emerin, whereas differentiating nurse cells predominantly express LamC and emerin2. A change in LamC-specific localization also occurs, wherein phosphorylated LamC redistributes to the nuclear interior only in the oocyte, prior to transcriptional reactivation of the meiotic genome. These changes support existing concepts that LamC promotes differentiation, a premise that was tested. Remarkably ectopic LamC production in GSCs did not promote premature differentiation. Increased LamC levels in differentiating germ cells altered internal nuclear structure, increased RNA production, and reduced female fertility due to defects in eggshell formation. These studies suggest differences between Drosophila lamins are regulatory, not functional, and reveal an unexpected robustness to level changes of a major scaffolding component of the NL.

Academic writing and identity: evaluative discourse in academic papers across cohorts of 20th century linguists

Abstract Using a cohort sequential quantitative design and evaluative features drawn from Systemic Functional Grammar, this study investigates diachronic variation in linguists’ use of evaluation to perform scholarly identities in English academic writing. More specifically, it focuses on the use of statements, commands, modality, comment assessment, and positive and negative lexis, in early and late career papers from 30 linguists born between 1905 and 1960. These linguists were grouped into three cohorts based on year of birth and studied in terms of variation along developmental and cross-generational timescales. Within the developmental timescale, scholars were found to use more evaluation in early career writing than in late career writing. Cohort-specific developmental changes are identified in the frequency of modality and comment assessment. Developmental and cohort-specific trends are found to occur within the backdrop of an overall decrease in the use of evaluative language within the discipline. Results point to a complex diachronic model of academic identity enactment in writing, whereby evaluative features pattern in similar or different ways depending on the timescale considered.