Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “developmental dynamics”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 919 records · Page 51Linked to original sources
PubMed2006

On the dynamic nature of positional information.

Morphogenetic fields are among the most fundamental concepts of embryology. However, they are also among the most ill-defined, since they consist of dynamic regulatory processes whose exact nature remains elusive. In order to achieve a more rigorous definition of a developmental field, Lewis Wolpert introduced the concept of positional information illustrated by his French Flag model. Here we argue that Wolpert's positional information - a static coordinate system defining a field - lacks essential properties of the original field concept. We show how data-driven mathematical modeling approaches now enable us to study regulatory processes in a way that is qualitatively different from our previous level of understanding. As an example, we review our recent analysis of segmentation gene expression in the blastoderm embryo of the fruit fly Drosophila melanogaster. Based on this analysis, we propose a revised French Flag, which incorporates the dynamic, feedback-driven nature of pattern formation in the Drosophila blastoderm.

Animals↗
PubMedDate not supplied

Dynamic three-dimensional visualization of collagen matrix remodeling and cytoskeletal organization in living corneal fibroblasts.

The remodeling of extracellular matrices by cells plays a defining role in developmental morphogenesis and wound healing, as well as in tissue engineering. Three-dimensional (3-D) type I collagen matrices have been used extensively as an in vitro model for studying cell-induced matrix reorganization at the macroscopic level. However, few studies have directly assessed the dynamic process of 3-D matrix remodeling at the cellular and subcellular level. We recently developed an experimental model for investigating cell-matrix mechanical interactions by plating green fluorescen protein (GFP)-zyxin transfected cells inside fibrillar collagen matrices and performing high-magnification time-lapse differential interference microscopy (DIC) and wide-field fluorescent imaging. In this study, we extend this experimental model by performing four-dimensional (4-D) reflected light and fluorescent confocal imaging (using either visible light or multiphoton excitation) of living corneal fibroblasts transfected to express GFP-zyxin or GFP-alpha-actinin, 18 h after plating inside 3-D collagen matrices. Reflected light confocal imaging allowed detailed visualization of the cells and the fibrillar collagen surrounding them. By overlaying maximum intensity projections of reflected light and GFP-zyxin or GFP-alpha-actinin images and generating stereo pair reconstructions, 3-D interactions between focal adhesions and collagen fibrils in living cells could be visualized directly. Focal adhesions were generally oriented parallel to the direction of collagen fibril alignment in front of the cell. Killing the cells induced relaxation of transient cell-induced tension on the matrix; however, significant permanent remodeling always remained. Time-lapse 3-D imaging demonstrated an active response to the Rho-kinase inhibitor Y-27632, as indicated by cell elongation, extracellular matrix relaxation, and extension of pseudopodial processes. It is interesting that, at higher cell densities, groups of collagen fibrils were compacted and aligned into straps between neighboring cells. Overall, the continued development and application of this new approach should provide important insights into the basic underlying biochemical and biomechanical regulatory mechanisms controlling matrix remodeling by corneal fibroblasts.

Animals↗
PubMed1999

Joining group psychotherapy: developmental considerations.

This article examines the experience of new members joining an ongoing psychotherapy group. The group's stage of development and the new member's personality development are suggested to be important variables in this significant event. The experience of joining is found to share some things in common with the beginning phase of group for the group as a whole, but also noted are some unique elements. The process of joining is viewed as a highly anxious event for the new member, with antecedents in the individual's life experience. The new member is compromised by not knowing the group members, nor their shared history, norms, and dynamics. Concurrently, the group may experience a range of fears, wishes, and anxieties about the new member. Developmental considerations for the new member and the stage of group help to inform intervention strategies.

Adaptation, Psychological↗
PubMed2000

The developmental emergence of coupled activity as cooperative aggregation in rat pups.

Rat pups (Rattus norvegicus) are born blind and deaf yet manage to wriggle about in a huddle, dynamically adjusting their positions and thereby displaying thermoregulation and energy conservation at the level of the group. As pups develop, their activity and mobility outpace the development of their visual and auditory systems making it increasingly difficult to aggregate and maintain aggregation while still blind and deaf. The developmental emergence of coupled activity may be one mechanism that facilitates aggregation. Our previous research has shown that the activity of a seven-day-old pup is independent of the activity of the litter mates it contacts. However, we hypothesized that, by day 10, more active and mobile pups will exhibit coupled activity, becoming increasingly quiescent when in contact with other behaviourally quiescent pups. In order to test this hypothesis, we used individual-based modelling. Because the structure of the model was complex, we used a Darwinian algorithm for evolving a model that behaved like ten-day-old pups aggregating in an arena. Sensitivity to quiescent individuals was manifested in some litters by the transitory spreading of quiescence across aggregates of both real and virtual pups (a contagion effect). As pups develop, individual behaviour becomes increasingly contingent on the behaviour of others revealing what may be a basic component in the development of cooperative behaviour.

Algorithms↗
PubMed2001

Twinfilin is required for actin-dependent developmental processes in Drosophila.

The actin cytoskeleton is essential for cellular remodeling and many developmental and morphological processes. Twinfilin is a ubiquitous actin monomer-binding protein whose biological function has remained unclear. We discovered and cloned the Drosophila twinfilin homologue, and show that this protein is ubiquitously expressed in different tissues and developmental stages. A mutation in the twf gene leads to a number of developmental defects, including aberrant bristle morphology. This results from uncontrolled polymerization of actin filaments and misorientation of actin bundles in developing bristles. In wild-type bristles, twinfilin localizes diffusively to cytoplasm and to the ends of actin bundles, and may therefore be involved in localization of actin monomers in cells. We also show that twinfilin and the ADF/cofilin encoding gene twinstar interact genetically in bristle morphogenesis. These results demonstrate that the accurate regulation of size and dynamics of the actin monomer pool by twinfilin is essential for a number of actin-dependent developmental processes in multicellular eukaryotes.

Actin Cytoskeleton↗
PubMed2026

Morphological changes and transcriptomic insights into skeletal development of embryos and larvae of the sea urchin Strongylocentrotus intermedius.

To explore morphological features and molecular dynamics underlying skeletogenesis in the sea urchin Strongylocentrotus intermedius, we conducted combined morphological observation and comparative transcriptome analyses across representative embryonic and larval developmental stages. Morphological results showed that triradiate spicules first emerged at the gastrula stage. The 8-arm pluteus stage was identified as a key phase for skeletal remodeling, during which new three-radiate crystals transformed into complex stereoscopic ossicles including tube feet, spines and test plates. Transcriptomic data indicated that most differentially expressed genes (DEGs) were downregulated from the blastula to gastrula. The altered expression of basal metabolic genes and extracellular matrix genes including Colp2α and calm may be correlated with the linear mineralization of early spicules, which potentially reflects an energy adjustment pattern in developing larvae. During the transition from 6-arm to 8-arm pluteus, expression changes of calmodulin-like, Colp2α and SISin18G001660 suggest potential associations with regional calcium deposition and modifications of skeletal matrix properties. This work systematically characterizes morphological traits and transcriptional dynamics of skeletogenesis in S. intermedius. Its early spiculogenesis follows the conserved developmental pattern of echinoderms, while massive formation of stereoscopic ossicles occurs at the 8-arm pluteus stage. Stage-specific transcriptional changes across key larval skeletogenic stages are uncovered, offering transcriptomic resources for functional verification of skeletal regulatory genes.

Animals↗
PubMed1983

Manifestations of consciousness and the developmental phenomenon of death.

Recent developments in nursing science include the development of theoretic structures that focus on the developmental nature of the human life process. According to Rogers, this life process represents a unitary phenomenon within which change is constant and evolutionary. Such change occurs through a dynamic, rhythmic interaction between the person and the environment. A theoretic framework derived from conceptualizations of the life process with its associated manifestation of consciousness and the developmental phenomenon of death is presented. The concepts and identified propositions are related to specific empiric indicators for testing or measurement. Implications of the proposed relationships between state of consciousness and resolution of death anxiety for nursing practice are also discussed.

Anxiety↗
PubMed2006

Helper T cell-regulated B cell immunity.

In this review, we will discuss the cascade of cellular and molecular events in the immune response to protein antigens that regulate the development of high-affinity B cell memory. The behavior of antigen-experienced pMHCII+ dendritic cells DCs and the dynamics of their interaction with specific T-helper (Th) cells define the first developmental checkpoint for adaptive immunity in vivo. Recent studies provide insight into the basis of Th cell clonal selection and the requirements and consequences of antigen priming in this responsive Th cell compartment. Antigen-specific Th cells expand to become the cognate regulators of effector B cell responses and initiators of the germinal center reaction and memory B cell development. We will discuss the development and role of these diverse mixtures of antigen-specific B cells in the control of B cell memory and long-term humoral immunity that underpin effective protein vaccination.

Animals↗
PubMed2006

Molecular signatures define myogenic stem cell populations.

Developmental and regenerative mechanisms are directed by stem cell populations. Skeletal muscle is a dynamic tissue that is capable of adapting to stress and severe injury due to a resident somatic stem cell population. In response to a severe injury that destroys upward of 90% of the tissue, skeletal muscle efficiently and reproducibly regenerates damaged tissue and restores the cellular architecture within a 2-wk period. Recent studies have localized and examined the molecular regulation of skeletal muscle stem cell populations using emerging molecular biological technologies. These studies enhance the understanding of the regulatory mechanisms that direct the somatic stem cell populations and the role they play in development and regeneration. Furthermore, these basic science studies will serve as a platform for future therapies directed toward patients with myopathic diseases.

Animals↗
PubMed1995

Relationships between complex Delta expression and the specification of retinal cell fates during Drosophila eye development.

Analysis of retinal development in Delta (Dl) temperature-sensitive mutants reveals requirements for Delta function in the specification of all retinal cells, including photoreceptors, cone cells, pigment cells and cells that make up interommatidial bristles. In situ hybridization and immunohistochemistry indicate that Delta is expressed dynamically during the specification of different cell types. Comparisons of Delta expression patterns with developmental defects in Dl mutants implies that Delta functions in a cell-nonautonomous manner in the specification of photoreceptors. Delta protein resides predominantly in subcellular vesicles located primarily at the apical ends of developing retinal cells. Localization of Delta protein in Dl and shibire tsl mutants implies that Delta is targeted to the cell surface, but is efficiently removed via endocytosis, resulting in vesicular accumulation.

Animals↗
PubMed2006

Chromatin structure and gene regulation in T cell development and function.

Transcription factors control gene expression programs in the context of the chromatin structure of their target genes. DNA methylation, post-translational histone modifications such as acetylation and methylation, and higher order chromatin organization allow the maintenance of gene expression patterns through mitosis, but how do they accommodate developmentally regulated changes in gene expression programs? Although histone acetylation and deacetylation are in dynamic equilibrium and mechanisms for the removal of methyl groups from histones are emerging, the extent to which there is active demethylation of DNA remains controversial. Looking at chromatin in the three-dimensional space of the nucleus, recent work demonstrates that gene regulation involves contacts between regulatory elements within genes or gene clusters on the same chromosome (in cis) and between different chromosomes (in trans). Finally, non-coding RNAs make a significant contribution to transcriptional and post-transcriptional gene silencing. Together, these advances contribute to an understanding of how gene expression programs are established, maintained and modified during development.

Animals↗
PubMed2005

The small GTPase ADP-ribosylation factor 6 negatively regulates dendritic spine formation.

Actin cytoskeletal reorganization and membrane trafficking are important for spine morphogenesis. Here we investigated whether the small GTPase, ADP-ribosylation factor 6 (ARF6), which regulates actin dynamics and peripheral vesicular trafficking, is involved in the regulation of spine formation. The developmental expression pattern of ARF6 in mouse hippocampus was similar to that of the post-synaptic density protein-95, and these molecules colocalized in mouse hippocampal neurons. Overexpression of a constitutively active ARF6 mutant in cultured hippocampal neurons decreased the spine density, whereas a dominant-negative ARF6 mutant increased the density. These results demonstrate a novel function for ARF6 as a key regulator of spine formation.

ADP-Ribosylation Factor 6↗
PubMed2026

Temporal DIA-MS proteomics reveals coordinated metabolic reprogramming associated with oil accumulation in oil palm mesocarp.

Oil palm (Elaeis guineensis Jacq.) is the most productive oil-bearing crop globally, yet the molecular basis of mesocarp development and lipid accumulation remains poorly understood. Ultra-deep data-independent acquisition mass spectrometry (DIA-MS) was applied to characterize proteome dynamics in two contrasting genotypes, seedless (KS) and thin-shelled (TS), across five developmental stages (P1-P5) spanning fruit development to mature oil accumulation. Phenotypic analysis revealed higher mesocarp proportion and oil content in KS during late maturation. A total of 137,615 peptides corresponding to 12,163 protein groups were identified, providing a temporal proteomic landscape of mesocarp development. Multivariate analysis indicated that developmental progression was the primary contributor to proteomic variation, whereas genotype-associated differences increased during lipid accumulation. Differentially abundant proteins were mainly associated with carbohydrate metabolism, photosynthesis, proteolysis, antioxidant responses, and lipid biosynthesis. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and KOG analyses suggested extensive remodeling of metabolic networks, including developmental changes in photosynthesis-associated proteins and increased representation of lipid-associated pathways during maturation. Weighted protein co-expression network analysis identified 17 modules associated with developmental progression and lipid accumulation, highlighting candidate proteins involved in carbon metabolism, energy production, and cellular protection. Genes encoding selected hub protein candidates were further examined by RT-qPCR. Biochemical analyses supported these proteomic patterns, showing increased acetyl-CoA availability, enhanced antioxidant enzyme activities (SOD, CAT, APX, and GR), improved GSH/GSSG balance, and reduced oxidative damage in KS. Together, these findings provide a temporal proteomic and biochemical framework for understanding genotype-associated differences in oil accumulation and identify candidate metabolic networks for functional studies.

Carbon metabolism↗
PubMed2000

Genetic evaluation and counseling in head and neck syndromes.

Genetic diagnosis and counseling are dynamic areas of clinical medicine that must keep pace with the rapid advances in developmental and molecular biology. Identification of developmental pathways in primitive organisms has often led to the recognition of similar programs for development in vertebrates. An understanding of the function of genes studied in mice through knock-out and targeted mutation studies provides animal models for human dysmorphogenetic syndromes and candidate genes for human syndromes. As soon as a gene is cloned for a human disorder and mutations are identified in affected individuals, clinical applications in diagnosis, prediction, and prevention rapidly develop. Understanding how a gene functions and the consequences of its mutation will aid in counseling and will help determine prognosis. Some mutations that interrupt pathways early in development will cause malformations that are static or nonprogressive, as seen in PAX6 and Shh mutations. Others, such as FGFR mutations, will continue to interfere with normal morphogenesis throughout the period of growth and development in the regions affected by the mutated gene. Clinical geneticists and genetic counselors, by assuming responsibility for identifying individuals with or at risk for genetic disorders, serve as interpreters and guides to the options presented by this new technology.

Animals↗
PubMed2001

Spontaneous discharge and response characteristics of central otolith neurons of rats during postnatal development.

To study the developmental profile of otolith-related vestibular nuclear neurons, their spontaneous activities and response dynamics were examined in decerebrate rats aged seven, 14, 21 and 84 (adult) days. Extracellular recordings were performed in the lateral and descending vestibular nucleus of animals held at the stationary position in the earth-horizontal or subjected to constant velocity off-vertical axis rotation, which selectively stimulates the otolith receptors. All neurons displayed sinusoidal position-dependent modulation in discharge rate, indicating their capability in coding spatial information during low-frequency head movement. Some neurons showed a full-cycle response to off-vertical axis rotation (non-clipped), while other neurons were silenced in discharge during parts of each rotary cycle (clipped). In seven-day-old rats, three-quarters of the responsive neurons sampled were clipped and the proportion progressively decreased to less than one-quarter in adult rats. In each age group, the clipped neurons discharged in approximately 60% of the stimulus cycle. Response gains of the neurons increased with age, reaching a plateau from 21 days of age for clipped neurons and 14 days for non-clipped neurons. The clipped neurons demonstrated higher response gains than the non-clipped neurons at or beyond 21 days of age. Spontaneous activities of the neurons at the stationary and earth-horizontal positions were analysed in relation to their response gains; a positive correlation was observed from 14 days of age onwards. Both types of neurons showed progressive increase in spontaneous activity as the rats matured, though the clipped neurons exhibited significantly lower resting rates than the non-clipped neurons at each of the age groups studied. Some neurons that responded to off-vertical axis rotation were not spontaneously active at the stationary position, but the proportion of these decreased significantly with age. The coefficient of variation of each age group showed a bimodal distribution, thereby allowing spontaneously active neurons to be assigned as regular or irregular. Though the vast majority of both the clipped and non-clipped neurons showed irregular discharge patterns at seven days of age, the overall population became more regular as the rats matured. Irregular neurons of young rats exhibited phase-stable and phase-shift responses, while those of older rats showed only the phase-stable response. This distinction was not observed amongst regular neurons over the ages studied. Our results reveal features of central otolith neurons that can be taken as signs of maturation during the first three postnatal weeks. These neuronal features provide the framework for the analysis of behaviours mediated by the otolith system during postnatal maturation.

Action Potentials↗
PubMedDate not supplied

Analysis of Fgf15 expression pattern in the mouse neural tube.

The dynamic process of neural tube regionalization in vertebrates is regulated by the expression of developmental genes which appear in characteristic patterns at neuroepithelial transversal domains, which are called secondary organizers. The molecular code present in these neuroepithelial organizers controls the generation of morphogenetic signals that induce and maintain regional characteristics in the surrounding neuroepithelium. The product of the Fgf8 gene is a secreted protein that has been demonstrated to be the key molecule for the isthmic organizer and is also expressed in two other organizer regions: the zona limitans and the anterior neural ridge. Here we analyze the expression of Fgf15 at different stages of mouse development in relation to Fgf8 and Otx2 expression patterns.

Animals↗
PubMedDate not supplied

Synaptic control of motoneuron excitability in rodents: from months to milliseconds.

1. Motoneurons (MN) shape motor patterns by transforming inputs into action potential output. This transformation, excitability, is determined by an interaction between synaptic inputs and intrinsic membrane properties. Excitability is not static, but changes over multiple time scales. The purpose of the present paper is to review our recent data on synaptic factors important in the dynamic control of MN excitability over time scales ranging from weeks to milliseconds. 2. Developmental changes in modulation of MN excitability are well established. Noradrenergic potentiation of hypoglossal (XII) MN inspiratory activity in rhythmically active medullary slice preparations from rodents increases during the first two postnatal weeks. This is due to increasing alpha 1- and beta-adrenoceptor excitatory mechanisms and to a decreasing inhibitory mechanism mediated by alpha 2-adrenoceptors. Over a similar period, ATP potentiation of XII inspiratory activity does not change. 3. Motoneuron excitability may also change on a faster time scale, such as between different behaviours or different phases of a behaviour. Examination of this has been confounded by the fact that excitatory synaptic drives underlying behaviour can obscure smaller concurrent changes in excitability. Using the rhythmically active neonatal rat brain-stem-spinal cord preparation, we blocked excitatory inspiratory drive to phrenic MN (PMN) to reveal a reduction in PMN excitability specific to the inspiratory phase that: (i) arises from an inhibitory GABAergic input; (ii) is not mediated by recurrent pathways; and (iii) is proportional to and synchronous with the excitatory inspiratory input. We propose that the proportionality of the concurrent inhibitory and excitatory drives provides a means for phase-specific modulation of PMN gain. 4. Modulation across such diverse time scales emphasizes the active role that synaptic factors play in controlling MN excitability and shaping behaviour.

Adenosine Triphosphate↗
PubMed2005

Dynamic transcriptional regulatory complexes, including E2F4, p107, p130, and Sp1, control fibroblast growth factor receptor 1 gene expression during myogenesis.

Developmentally controlled transcriptional regulation of myogenic cell proliferation and differentiation via expression of the fibroblast growth factor receptor 1 (FGFR1) gene is positively regulated by Sp1 and negatively regulated by E2F4-based transcriptional complexes. We report that p107 and p130 formed transcriptional complexes with E2F4 on the FGFR1 promoter and repressed FGFR1 gene transcription in myogenic cells. However, in Drosophila melanogaster SL2 cells, only p107 was able to repress Sp1-mediated transactivation of the FGFR1 promoter. Gel shift assays using transfected myoblast nuclear extracts showed that ectopic p107 reduced Sp1 occupancy of the proximal Sp binding site of the FGFR1 promoter, and coimmunoprecipitation studies indicated that Sp1 interacts with p107 but not with p130. Gel shift assays also demonstrated that Sp1 interacted with p107 in E2F4-p107 transcriptional complexes in myoblasts. The nature of the repressor transcriptional complex was altered in differentiated muscle fibers by the relative loss of the E2F4-p107-Sp1 transcription complex and replacement by the repressor E2F4-p130 complex. These findings demonstrate that activation and repression of FGFR1 gene transcription is governed by interplay between Sp1, p107, p130, and E2F4 in distinct transcriptional complexes during skeletal muscle development.

Animals↗