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Results for “developmental dynamics”

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PubMed1998

Morphology and development of the postdiaphragmatic part of the sympathetic trunk in the pig (Sus scrofa L.) during its prenatal period.

The experiment was conducted on 36 swine fetuses divided into the three developmental groups described by Marrable (1971). In the postdiaphragmatic part, 10 to 20 primary ganglia were found in the sympathetic trunk. They had fused with the secondary structures, and hence the sympathetic trunks studied finally consisted of 6-16 ganglia. It is remarkable that the higher number of primary ganglia did not correspond with the higher number of secondary ones. The variation in the number of secondary ganglia was mainly connected with the interganglionic fusion occurring in the section studied. The standard variation in the length of the sympathetic ganglia increased considerably with the age of the fetuses as well as the analogous coefficient of variation. The analysis of the statistical parameters referring to the ganglia of the investigated section of the sympathetic trunk investigated indicated the growth of its developmental dynamics, which did not occur until the terminal period of gestation.

Animals↗
PubMed2001

Distinct mechanisms control RNA polymerase II recruitment to a tissue-specific locus control region and a downstream promoter.

Histone acetylation precedes activation of many genes. However, the establishment and consequences of long-range acetylation patterns are poorly understood. To define molecular determinants of the developmentally dynamic histone acetylation pattern of the beta-globin locus, we compared acetylation of the locus in MEL and CB3 erythroleukemia cells. CB3 cells lack the beta-globin locus control region (LCR) binding protein p45/NF-E2. We found that p45/NF-E2 was required for histone hyperacetylation at adult beta-globin promoters approximately 50 kilobases downstream of the LCR, but not at the LCR. Surprisingly, RNA polymerase II associated with the LCR in a p45/NF-E2-independent manner, while its recruitment to the promoter required p45/NF-E2. We propose that polymerase accesses the LCR and p45/NF-E2 induces long-range transfer of polymerase to the promoter, resulting in transcriptional activation.

Acetylation↗
PubMedDate not supplied

Shifting relationships between photoreceptors and pigment epithelial cells in monkey retina: implications for the development of retinal topography.

This study examines the spatiotemporal relationships between retinal pigment epithelium (RPE) and photoreceptors (PR) during development of Macaca nemestrina retina. Our aim was to learn more about the developmental dynamics of these two important cell populations, particularly whether development changes in RPE cell densities mimic those of PR at selected retinal points. Twelve eyes ranging in age from 100 fetal days (Fd) to adulthood were flatmounted; the retinal perimeters were traced; and then sample punches were taken of the RPE and neural retina at the fovea, optic disc, mid- and far-nasal periphery, and far temporal, inferior and superior periphery. The two tissues were gently separated and the RPE cells and photoreceptors from the same region of the punch were counted using Nomarski contrast interference optics. We found that the total number of cones remains stable around 4 million between Fd100 and adulthood, but RPE number increases from 1.6 million at Fd100 to 2.56 million in adulthood. At the fovea, the core:RPE ratio increases from 5.4:1 at Fd100 to 28:1 by adulthood. In the temporal periphery by contrast, the cone:RPE ratio declines from 2.2:1 at Fd100-110 to less than 1:1 in the adult. In the vicinity of the optic disc, the ratio of (cones+rods); RPE remains around 35:1 throughout development, but in the retinal periphery it decreases to the adult value of 22:1. These changing ratios indicate that photoreceptors and RPE cells are redistributed independently during development, and that these two cellular sheets slide over one another to achieve their final distribution. This situation suggests that the forces or factors causing foveation are intrinsic to the neural retina.

Aging↗
PubMed1999

Stability and change in mothers' representations of their relationship with their toddlers.

This study examined several issues in the developmental dynamics of parents' representations of their relationship with their toddlers. The authors studied 125 mothers and their firstborn toddler sons over a 13-month period. Mothers took the Parent Development Interview twice, when children were 15 and 28 months of age. Home observations of parent-child interactions and maternal ratings of daily hassles were collected when children were 21 and 27 months of age. The 3 factors that characterized mothers' representations of their 15-month-old firstborn sons (Joy-Pleasure/Coherence, Anger, Guilt-Separation Distress) also fit the data very well for their 28-month-old sons. Although there were no changes in average levels of mothers' (a) joy, pleasure, and coherence and (b) guilt and separation distress from 15 to 28 months, there was a significant increase in mothers' levels of anger. Stability analyses suggested a dynamic relationship between mothers' representations of joy, pleasure, and coherence and of anger over the 13-month period. Finally, changes in mothers' representations were predictable by positive mothering (which led to increased joy, pleasure, and coherence) and by parenting daily hassles (which led to more anger).

Adult↗
PubMed2003

A prolegomenon for a viable evolutionary psychology--the myth and the reality: comment on Lickliter and Honeycutt (2003).

R. Lickliter and H. Honeycutt (2003) attempted to create a dynamic developmental systems theory of evolutionary psychology. In this commentary, the author argues that the quality of their reasoning, their conflation of evolution and evolution by natural selection, their failure to explain the relative importance of multilevel, epigenetic interactions, their lack of population thinking, and their failure to define adaptation undermines their endeavor.

Biological Evolution↗
PubMed2002

The presumption of sociality: social learning in diverse contexts in brown-headed cowbirds (Molothrus ater).

Data are presented on social and vocal learning in cowbirds (Molothrus ater) housed in large aviaries and given more degrees of freedom than in conventional experimental studies. The studies show that social and vocal outcomes are facultative responses to social contexts. Several findings are reviewed: First, cowbirds quickly self-organize into groups by age and sex; second, opportunities to interact across age and sex do exist and affect courtship competence; third, female cowbirds organize themselves differently in the presence and absence of male competition; and fourth, young, naive cowbirds show rapid and differential sensitivity to group dynamics. Taken as a whole, the data show that social Umwelten are dynamic, developmental ecologies.

Age Factors↗
PubMed2003

Disability in the family: a life span perspective.

This article provides an overview of disability in families. The goal of the article is to raise awareness of the status of people with disabilities and their families to develop culturally relevant psychological support. Families have widely varying perspectives on disability; those perspectives influence responses to disability from the preconception and prenatal developmental stages through old age. An international literature review is provided with consideration of cultural meanings of disability, preparation for dealing with disability, coping strategies, support, developmental dynamics, competing needs of family members, and ethics. Voices of people with disabilities and their families are included.

Adaptation, Psychological↗
PubMed1996

Semaphorin III is needed for normal patterning and growth of nerves, bones and heart.

The expression patterns of the recently discovered family of semaphorin genes suggests that they have widespread roles in embryonic development. Some seem to guide neuronal growth cones, but otherwise their functions are unknown. Semaphorin III is a membrane-associated secreted protein with a developmentally dynamic pattern of expression, including particular domains of the nervous system, the borders of developing bones, and the heart. In vitro, semaphorin III causes growth-cone collapse, and repels cutaneous sensory axons from the ventral spinal cord. Mutants in the Drosophila gene semaII, which encodes a related semaphorin, die after eclosion, but no responsible abnormality is evident. We have generated mice mutant in the semaIII gene by homologous recombination. Here we show that in the mutants, some sensory axons project into inappropriate regions of the spinal cord where semaIII is normally expressed. The cerebral cortex of homozygous mutant mice shows a paucity of neuropil and abnormally oriented neuronal processes, especially of the large pyramidal neurons. Certain embryonic bones and cartilaginous structures develop abnormally, with vertebral fusions and partial rib duplications. The few mice that survive more than a few days postnatally manifest pronounced and selective hypertrophy of the right ventricle of the heart and dilation of the right atrium. Thus, semaphorin III might serve as a signal that restrains growth in several developing organs.

Animals↗
PubMed2006

Identification of the death zone: a spatially restricted region for programmed cell death that sculpts the fly eye.

Programmed cell death (PCD) sculpts many developing tissues. The final patterning step of the Drosophila retina is the elimination, through PCD, of a subset of interommatidial lattice cells during pupation. It is not understood how this process is spatially regulated to ensure that cells die in the proper positions. To address this, we observed PCD of lattice cells in the pupal retina in real time. This live-visualization method demonstrates that lattice cell apoptosis is a highly specific process. In all, 85% of lattice cells die in exclusive 'death zone' positions between adjacent ommatidia. In contrast, cells that make specific contacts with primary pigment cells are protected from death. Two signaling pathways, Drosophila epidermal growth factor receptor (dEgfr) and Notch, that are thought to be central to the regulation of lattice cell survival and death, are not sufficient to establish the death zone. Thus, application of live visualization to the fly eye gives new insight into a dynamic developmental process.

Animals↗
PubMed2001

Effects of the curly tail genotype on neuroepithelial integrity and cell proliferation during late stages of primary neurulation.

The curly tail (ct/ct) mouse mutant shows a high frequency of delay or failure of neural tube closure, and is a good model for human neural tube defects, particularly spina bifida. In a previous study we defined distinct domains of gene expression in the caudal region of non-mutant embryos during posterior (caudal) neuropore closure (Gofflot et al. Developmental Dynamics 210, 431-445, 1997). Here we use BrdU incorporation into S-phase nuclei to investigate the relationship between cell proliferation and the previously described gene expression domains in ct/ct mutant embryos. The BrdU-immunostained sections were also examined for abnormalities of tissue structure; immunohistochemical detection of perlecan (an extracellular heparan sulphate proteoglycan) was used as an indicator of neuroepithelial basement membrane structure and function. Quantitation of BrdU uptake revealed that at early stages of neurulation, cell proliferation was specifically reduced in the paraxial mesoderm of all ct/ct embryos compared with wild type controls, but at later stages (more cranial levels) it was increased. Those ct/ct embryos with enlarged posterior neuropore (indicating delay of closure) additionally showed an increased BrdU labelling index within the open neuroepithelium at all axial levels; however, this tissue was highly abnormal with respect to cell and nuclear morphology. It showed cell death and loss of cells from the apical surface, basement membrane defects including increased perlecan immunoreactivity, and increased separation from the underlying mesenchyme and notochord. These observations suggest that the mechanism of delay or failure of neuroepithelial curvature that leads to neural tube defects in curly tail embryos involves abnormalities of neuroepithelial-mesenchymal interactions that may be initiated by abnormal cellular function within the neuroepithelium. Minor histological and proliferation abnormalities are present in all ct/ct embryos, regardless of phenotype.

Animals↗
PubMed2003

An ancestral secretory apparatus in the protozoan parasite Giardia intestinalis.

The protozoan parasite Giardia intestinalis belongs to one of the earliest diverged eukaryotic lineages. This is also reflected in a simple intracellular organization, as Giardia lacks common subcellular compartments such as mitochondria, peroxisomes, and apparently also a Golgi apparatus. During encystation, developmentally regulated formation of large secretory compartments containing cyst wall material occurs. Despite the lack of any morphological similarities, these encystation-specific vesicles (ESVs) show several biochemical characteristics of maturing Golgi cisternae. Previous studies suggested that Golgi structure and function are induced only during encystation in Giardia, giving rise to the hypothesis that ESVs, as a Giardia Golgi equivalent, are generated de novo. Alternatively, ESV compartments could be built on the template structure of a cryptic Golgi in trophozoites in response to ER export of cyst wall material during encystation. We addressed this question by defining the molecular framework of the Giardia secretory apparatus using a comparative genomic approach. Analysis of the corresponding transcriptome during growth and encystation revealed surprisingly little stage-specific regulation. A panel of antibodies was generated against selected marker proteins to investigate the developmental dynamics of the endomembrane system. We show evidence that Giardia accommodates the export of large amounts of cyst wall material through re-organization of membrane compartment(s) in trophozoites with biochemical similarities to ESVs. This suggests that ESVs are selectively stabilized Golgi-like compartments in a unique and archetypical secretory system, which arise from a structural template in trophozoites rather than being generated de novo.

Animals↗
PubMed2006

Comparison of environmental and mutational variation in flowering time in Arabidopsis.

Developmental dynamics can be influenced by external and endogenous factors in a more or less analogous manner. To compare the phenotypic effects of (i) environmental [i.e. standard (stPhP) and extended (exPhP) photoperiods] changes in Arabidopsis wild types and (ii) endogenous genetic variation in eav1-eav61 early flowering mutants, two temporal indicators were analysed, the time to bolting (DtB) and the number of leaves (TLN). It was found that DtB and TLN are differentially affected in different environmental and genetic contexts, and some factors of dynamic convergence were identified. The quantitative response to photoperiod is markedly contingent on the phototrophic input for DtB, but less so for TLN. To discriminate the light quantity and period components in DtB, two novel temporal indicators were determined, LtB (photosynthetic time to bolting) and PChron (DtB h(-1) of photoperiod), respectively. The use of PChron results in a coincidence of the variation profiles across stPhP and exPhP, interpreted as a buffering of the trophic response. Unlike natural accessions and later flowering mutants, the variation profiles across stPhP and eav mutants are significantly divergent, pointing to differences in environmental and genetic variation in flowering time. Yet, phenocopy effects and dynamic convergence between wild-type and mutant profiles are detected by using exPhP and the LtB indicator. Additional analyses of the cauline leaf number (CLN) show that the apical and basal boundaries of the primary inflorescence vary co-ordinately. The finding that the correlativity between CLN and TLN changes across photoperiods suggests that different states of intra-connectedness are involved in ontogenetic specification of flowering time and embodied in the primary inflorescence.

Arabidopsis↗
PubMed2026

Transcriptional and phytohormonal regulation of positional ear development reveals yield strategies in maize.

Maize (Zea mays L.) is a vital global crop, contributing ∼37% of annual grain production. Enhancing yield per unit area is crucial for food security, yet research has primarily focused on single-ear traits, overlooking the regulation of double ears-a key determinant of prolificacy. While secondary ears drive yield variability under prolificacy-favoring conditions, the mechanisms governing ear formation across shoot positions remain poorly understood. Here, we performed high-resolution transcriptomic analysis of 66 samples from three ear types (primary, secondary and third) in maize inbred B73. We uncovered distinct hormonal developmental dynamics: strigolactone (SL) signaling genes, particularly SBP transcription factors, dominated in primary (I) ears, whereas ethylene-related genes (e.g., ZmEREB131, ZmACCO35) were enriched in third (III) ears. Functional validation confirmed that knockout of ZmEREB131 and ZmACCO35 accelerated development and elongated ears compared to wild-type, implicating ethylene (ETH) signaling in ear maturation arrest. Notably, SL inhibitor application synchronized primary and secondary ear development, boosting total yield by >20% without compromising primary ear performance. Our study elucidates the transcriptional networks underlying differential ear development and provides actionable strategies for yield improvement through targeted hormonal modulation. These findings advance the understanding of maize inflorescence biology and offer molecular tools for breeding high-yielding varieties.

RNA-seq↗
PubMed2003

2,3,7,8-tetrachlorodibenzo-p-dioxin inhibits zebrafish caudal fin regeneration.

Adult zebrafish completely regenerate their caudal fins following partial amputation. Fin regrowth can easily be monitored in vivo and regenerating tissues can be used to study this dynamic developmental process. In this study we determined that fin regeneration is significantly affected by exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Zebrafish caudal fins were partially amputated, and the fish received intraperitoneal (ip) injection of 2.8, 14, or 70 ng/g weight TCDD or vehicle control. By 7 days postamputation, fish exposed to the highest concentration of TCDD regenerated 15% of their fin compared to 65% regrowth in control fish. To determine if this effect was stage specific, zebrafish were exposed to 70 ng/g TCDD on 1, 2, 3, or 4 days postamputation. Fin regeneration was significantly inhibited at all time points following TCDD exposure. TCDD exposure also induced hyperpigmentation in de novo tissue. Zebrafish were dosed with BrdU, following fin amputation and TCDD exposure, to study changes in cell proliferation. By 4 days postamputation, cell proliferation rates were significantly lower in TCDD-exposed fish. TCDD toxicity is mediated through the aryl hydrocarbon receptor (AHR), and RT-PCR experiments confirmed AHR2, ARNT2b, and TCDD-dependent CYP1A expression in the regenerating tissue. These results demonstrate that zebrafish caudal fin regeneration is a unique model to investigate molecular mechanism(s) of TCDD toxicity.

Animals↗
PubMed1989

Focal inpatient treatment planning.

Focal Inpatient Treatment Planning (FITP) is a new method of organizing and choosing among the many data available to the inpatient clinician. FITP emphasizes one Focal Problem, provides criteria for defining it, makes it possible to formulate the problem in operational language, channels free-ranging case discussion into workaday terms, invites the clinician to make explicit a sophisticated view of pathogenesis; including developmental, dynamic, and contextual factors, and ties formulation to intervention through explicit objectives. By requiring language that is jargon-free and accessible to patients and parents, FITP fosters empathy and alliance between the treatment community and the domain of the patient. This paper describes and illustrates FITP and provides guidelines for its implementation by an inpatient child and adolescent psychiatry service.

Adolescent↗
PubMed2002

Reaction-diffusion models of within-feather pigmentation patterning.

Feathers are complex, branched keratin structures that exhibit a diversity of pigmentation patterns. Feather pigments are transferred into developing feather keratinocytes from pigment cells that migrate into the tubular feather germ from the dermis. Within-feather pigment patterns are determined by differential pigmentation of keratinocytes within independent barb ridges during feather development. Little is known about the molecular mechanisms that determine which keratinocytes receive pigment. We apply reaction-diffusion models to the growth of within-feather pigment patterns based on a realistic model of feather growth. These models accurately simulate the growth of a diversity of the within-feather pigmentation patterns found in real feathers, including a central patch, a 'hollow' central patch, concentric central patches, bars, chevrons, a central circular spot, rows of paired spots, and arrays of offset dots. The models can also simulate the complex transitions between distinct pigmentation patterns among feathers observed in real avian plumages, including transitions from bars to chevrons, bars to paired dots, and bars to arrays of dots. The congruence between the developmental dynamics of the simulated and observed feather patterns indicates that the reaction-diffusion models provide a realistic and accurate description of the determination of pigment pattern within avian feather follicles. The models support the hypothesis that within-feather pigmentation patterning is determined by antagonistic interactions among molecular expression gradients within the tubular follicle and feather germ.

Animals↗
PubMed2005

Genome-wide HP1 binding in Drosophila: developmental plasticity and genomic targeting signals.

Heterochromatin protein 1 (HP1) is a major component of heterochromatin. It was reported to bind to a large number of genes and to many, but not all, transposable elements (TEs). The genomic signals responsible for targeting of HP1 have remained elusive. Here, we use whole-genome and computational approaches to identify genomic features that are predictive of HP1 binding in Drosophila melanogaster. We show that genes in repeat-dense regions are more likely to be bound by HP1, particularly in pericentric chromosomal regions. We also demonstrate that TEs are only bound by HP1 if they are flanked by other repeats, suggesting a cooperative mechanism of binding. Genome-wide DamID mapping of HP1 in larvae and adult flies reveals that repeat-flanked genes typically bind HP1 throughout development, whereas repeat-free genes display developmentally dynamic HP1 association. Furthermore, computational analysis shows that HP1 preferentially binds to transcribed regions of long genes. Finally, we detect low but significant amounts of HP1 along the entire X chromosome in male, but not female, flies, suggesting a link between HP1 and the dosage compensation complex. These results provide insights into the mechanisms of HP1 targeting in the natural genomic context.

Animals↗
PubMed2004

Cerebral cortex three-dimensional profiling in human fetuses by magnetic resonance imaging.

Seven human fetuses of crown/rump length corresponding to gestational ages ranging from the 12th to the 16th week were studied using a paradigm based on three-dimensional reconstruction of the brain obtained by magnetic resonance imaging (MRI). The aim of the study was to evaluate brain morphology in situ and to describe developmental dynamics during an important period of fetal morphogenesis. Three-dimensional MRI showed the increasing degree of maturation of the brains; fronto-occipital distance, bitemporal distance and occipital angle were examined in all the fetuses. The data were interpreted by correlation with the internal structure as visualized using high-spatial-resolution MRI, acquired using a 4.7-T field intensity magnet with a gradient power of 20 G cm(-1). The spatial resolution was sufficient for a detailed detection of five layers, and the contrast was optimized using sequences with different degrees of T1 and T2 weighting. Using the latter, it was possible to visualize the subplate and marginal zones. The cortical thickness was mapped on to the hemispheric surface, describing the thickness gradient from the insular cortex to the periphery of the hemispheres. The study demonstrates the utility of MRI for studying brain development. The method provides a quantitative profiling of the brain, which allows the calculation of important morphological parameters, and it provides informative regarding transient features of the developing brain.

Cerebral Cortex↗