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Results for “developmental dynamics”

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PubMed1997

Self-organized huddles of rat pups modeled by simple rules of individual behavior.

Starting at infancy and continuing throughout adult life, huddling is a major component of the behavioral repertoire of Norway rats (Rattus norvegicus). Huddling behavior maintains the cohesion of litters throughout early life, and in adulthood, it remains a consistent feature of social behavior of R. norvegicus. During infancy, rats have severely limited sensorimotor capabilities, and yet they are capable of aggregating and display a form of group regulatory behavior that conserves metabolic effort and augments body temperature regulation. The functions of huddling are generally understood as group adaptations, which are beyond the capabilities of the individual infant rat. We show, however, that huddling as aggregative or cohesive behavior can emerge as a self-organizing process from autonomous individuals following simple sensorimotor rules. In our model, two sets of sensorimotor parameters characterize the topotaxic responses and the dynamics of contact in 7-day-old rats. The first set of parameters are conditional probabilities of activity and inactivity given prior activity or inactivity and the second set are preferences for objects in the infant rat's environment. We found that the behavior of the model and of actual rat pups compare very favorably, demonstrating that the aggregative feature of huddling can emerge from the local sensorimotor interactions of individuals, and that complex group regulatory behaviors in infant rats may also emerge from self-organizing processes. We discuss the model and the underlying approach as a paradigm for investigating the dynamics of social interactions, group behavior, and developmental change.

Animals↗
PubMed2004

What drives children's limb selection for reaching in hemispace?

Arguably, the act of reaching constitutes one of the most devoted lines of contemporary developmental research. In addition to the underlying dynamical characteristics of motor coordination, a key element in programming is limb selection, a phenomenon (handedness) that has so far resisted any reasonable unified explanation. From a more contemporary view, two factors appear to have the most influence on hand selection for a given task: motor dominance and attentional information related to task demands. This study was designed to determine what factor(s) influence choice of limb for reaching in hemispace in reference to motor dominance, object proximity, and a hemispheric bias favoring use of the hand on the same side as the stimulus. Strong right-handed children were asked to reach and retrieve a small object across right and left hemispace locations beginning with the arms uncrossed and arms-crossed. With the arms-crossed condition, an imagined and actual movement execution was administered. Results from the uncrossed condition supported previous reported findings for adults and children. That is, participants responded ipsilaterally using the hand on the same side as the stimulus, thus supporting the case for object proximity and hemispheric bias. However, in the arms-crossed condition the vast majority of participants preferred keeping the limbs crossed in response to right and left hemispace stimuli, which leads to the suggestion that object proximity rather than hemispheric bias was the driving factor in this context. The behavioral pattern for imagined and actual movement was not significantly different. Overall, the findings add to the growing acceptance that limb selection is task and context dependent, rather than a biologically based invariant feature of motor behavior.

Arm↗
PubMed1976

Differentiation of Bergmann glia cells in the cerebellum: a golgi study.

The migration of Bergmann glia cells from the external granular layer to the Purkinje cell layer and the differentiation of their processes were analyzed in Golgi-Cox preparations of the cerebellum of the rat. During their migration they showed numerous cytoplasmic excrescences and long thick processes, which suggested that they may follow ameboid form of movement for their migration. The differentiation of their processes was observed to involve a series of complex events related to retraction of the thick apical processes from the tips of which sheaves of filiform processes emerged, growth in the number and the thickness of the filiform processes, resorption of some of these filiform processes, cyclic changes in the appearance, resorption and reappearance of excrescences on the filiform processes, and changes in size and shape of the growth cones. These findings are discussed in the context of the role played by the Bergmann glia cells in the postnatal developmental events in the cerebellum, and the dynamic nature of differentiation of their processes.

Age Factors↗
PubMed1979

Management of acute psychologic problems in pediatric oncology.

Several psychologic issues in pediatric oncology are addressed and case illustrations of psychologic intervention for selected problems are offered. Psychologic intervention must take into account the patient's perception of his illness, the patient's developmental level, the parents' coping mechanisms, the dynamics of the child's emotional and behavioral responses, the staff's perception of the problems, and the community's capacity for reintegration of the patient. Each of these issues is addressed by use of case examples to demonstrate important aspects of psychosocial intervention.

Acting Out↗
PubMed2005

Development of the norepinephrine transporter in the rat CNS.

The norepinephrine transporter (NET) plays a major role in regulating the actions of norepinephrine by removing norepinephrine from the synapse. Many studies suggest norepinephrine plays an important role in regulating development of the CNS, pointing to NET as an important factor in this process. We examined the ontogeny of NET expression in rat brain at 5, 10, 15, 20 and 25 days postnatally (PND) and in adults, using quantitative autoradiography with [3H]nisoxetine as ligand. At PND 5 and 10 most forebrain areas had low NET expression (1-2 fmol/mg tissue). By PND 15 most forebrain areas increased NET expression approximately five-fold compared with PND 10, levels generally similar to those found in the adult brain. In contrast, NET development in the brainstem exhibited elevated densities at PND 5, 10 and 20 that decreased in the adult. The locus coeruleus, in particular, had very high NET expression in the early postnatal period that decreased dramatically in the adult brain. These data illustrate a dynamic ontogenic profile for NET, characterized by developmental increases in forebrain structures and contrasting decreases in the brainstem. The early postnatal expression of NET in brainstem and the subsequent decrease or loss of NET expression with maturation suggest an important role for this transporter and for norepinephrine in the development of many brain regions. These studies also have important implications for use of drugs targeting the noradrenergic system in children and adolescents, such as antidepressants and drugs of abuse.

Animals↗
PubMed2005

Auxin and embryo axis formation: the ends in sight?

The major axis of polarity of the plant embryo serves as a reference for the formation of meristems and, thus, for all subsequent development. Mechanisms underlying the establishment of the embryo axis itself have remained elusive. This is now changing with recent reports documenting a role for auxin in embryo axis formation. Auxin accumulates dynamically at specific positions that correlate with developmental decisions in early embryogenesis, and this ties developmental decisions to both transport regulators and components of the response machinery. A major challenge for the future is to determine how auxin-dependent processes interact with other as yet unknown factors to mediate differential gene expression patterns in early embryogenesis.

Embryonic Development↗
PubMedDate not supplied

Pathophysiology of cervical myelopathy.

BACKGROUND CONTENT: Cervical myelopathy is a group of closely related disorders usually caused by spondylosis or by ossification of the posterior longitudinal ligament and is characterized by compression of the cervical spinal cord or nerve roots by varying degrees and number of levels. The decrease in diameter of the vertebral canal secondary to disc degeneration and osteophytic spurs compresses the spinal cord and nerve roots at one or several levels, producing direct damage and often secondary ischemic changes. PURPOSE: Clinicians who treat cervical myelopathy cord injuries should have a basic understanding of the pathophysiology and the processes that are initiated after the spinal cord has been injured. STUDY DESIGN/SETTING: Literature review. METHODS: Literature review of human cervical myelopathy and clinically relevant animal models to further our understanding of the pathological mechanisms involved. RESULTS: The pathophysiology of cervical myelopathy involves static factors, which result in acquired or developmental stenosis of the cervical canal and dynamic factors, which involve repetitive injury to the cervical cord. These mechanical factors in turn result in direct injury to neurons and glia as well as a secondary cascade of events including ischemia, excitotoxicity, and apoptosis; a pathobiology similar to that occurring in traumatic spinal cord injury. CONCLUSIONS: This review summarizes some of the significant pathophysiological processes involved in cervical myelopathy.

Apoptosis↗
PubMed2026

Shared candidate genes associated with variation in egg size in cold-adapted and artificially selected Drosophila melanogaster.

The development of most multicellular organisms begins with oogenesis, the production of the egg. In D. melanogaster, egg size is a highly polygenic trait closely related to fitness. Elements of shifts in egg size have been widely studied and modeled, but the genes underlying this variation are still poorly understood. This study aimed to identify candidate genes associated with processes underlying egg-size variation using D. melanogaster as a model. In selection experiments, we generated large-egg populations from a shared ancestral population using both cold-adaptation and artificial selection, and identified candidate genes for the large-egg phenotype. Using whole-genome DNA sequencing and strict computational filtering, we uncovered single-nucleotide polymorphisms in 10 genes. Characterization of these candidates revealed functions in cytoskeletal dynamics, DNA replication and repair, intracellular signaling, and stem cell maintenance and differentiation. RT-PCR and qPCR were used to validate gene expression differences between cold-adapted lines and the Oregon R control (OrR) in a subset of the candidates. In RT-PCR, stathmin demonstrated a modified expression pattern in all cold-adapted lines relative to OrR controls. In qPCR experiments, Pde1c had significantly higher expression (p&#x202f;<&#x202f;0.05) in the cold-adapted flies compared to OrR controls for all three fly cages tested. For Ino80, significantly higher expression was observed for one of three cages while one cage showed lower expression. We have assembled a candidate list we hope will be a useful resource for researchers across specialties, from germ cells to cytoskeletal dynamics, to further investigate the genetic and developmental aspects of variation in egg size in D. melanogaster.

Animals↗
PubMed1995

The play approach to learning in the context of families and schools: an alternative paradigm for nutrition and fitness education in the 21st century.

An alternative paradigm for nutrition and fitness education centers on understanding and developing skill in implementing a play approach to learning about healthful eating and promoting active play in the context of the child, the family, and the school. The play approach is defined as a process for learning that is intrinsically motivated, enjoyable, freely chosen, nonliteral, safe, and actively engaged in by young learners. Making choices, assuming responsibility for one's decisions and actions, and having fun are inherent components of the play approach to learning. In this approach, internal cognitive transactions and intrinsic motivation are the primary forces that ultimately determine healthful choices and life habits. Theoretical models of children's learning--the dynamic systems theory and the cognitive-developmental theory of Jean Piaget--provide a theoretical basis for nutrition and fitness education in the 21st century. The ultimate goal is to develop partnerships of children, families, and schools in ways that promote the well-being of children and translate into healthful life habits. The play approach is an ongoing process of learning that is applicable to learners of all ages.

Adult↗
PubMedDate not supplied

Management of encopresis in early adolescence in a medical-psychiatric unit.

The aim of this work is to present the role of a medical-psychiatric unit in the treatment of chronic resistant encopresis in adolescence as an effective alternative to the standard approach. Four case reports are presented. The integrative program is based on full patient cooperation and involves separating the patient from the family environment and the use of medical intervention combined with modified behavioral therapy and parental education and guidance. The patient is given full responsibility for the cure. The median full hospital stay for our patients was 2 weeks, and outcome in all cases was complete remission. This experience suggests that chronic resistant encopresis in adolescents requires a different approach from the standard because of the patient's developmental stage and the often hostile family dynamics. A medical-psychiatric setting provides an excellent management milieu and can lead to a dramatic improvement in this chronic disabling condition.

Adolescent↗
PubMed2002

Cloning and developmental expression of a novel, secreted frizzled-related protein from the sea urchin, Strongylocentrotus purpuratus.

Wnt proteins and their receptors, members of the frizzled protein family, play a key role in regulating a wide range of developmental processes. Recently, putative regulators of Wnt signaling known as secreted frizzled-related proteins (SFRPs) have been identified in several vertebrates. Here, we describe the cloning of a novel SFRP (suSFRP1) from the sea urchin, Strongylocentrotus purpuratus. SuSFRP1 contains a putative signal sequence, four cysteine-rich domains and a single Ig domain. The developmental expression of suSFRP1 mRNA is highly dynamic and can be separated into three phases: (1) abrupt accumulation in most or all cells of the embryo at the early blastula stage; (2) restriction of expression to the prospective endoderm and animal pole region of the gastrula; and (3) expression in prospective muscle cells of the coelomic pouches during late embryogenesis.

Amino Acid Sequence↗
PubMed2003

Nuclear choreography: interpretations from living cells.

The advent of green fluorescent protein technology, its use in photobleaching experiments and the development of methods to rapidly acquire images and analyze complex datasets have opened the door to unraveling the mechanisms of nuclear functions in living cells. Studies over the past few years have characterized the movement of chromatin, nuclear proteins and nuclear bodies and, in some cases, correlated their dynamics with energy dependence, cell cycle progression, developmental changes, factor targeting and nuclear position. The mechanisms by which nuclear components move or are restrained have important implications for understanding not only the efficacy of nuclear functions but also the regulation of developmental programs and cellular growth.

Animals↗
PubMed2001

Stochastic WNT signaling between nonequivalent cells regulates adhesion but not fate in the two-cell leech embryo.

BACKGROUND: In the leech Helobdella robusta, an annelid worm, the early pattern of cell divisions is stereotyped. The unequal first cleavage yields cells AB and CD, which differ in size, cytoplasmic inheritance, normal fate, and developmental potential. RESULTS: Here we report a dynamic and transcription-independent pattern of WNT signaling in the two-cell stage of H. robusta. Surprisingly, HRO-WNT-A is first expressed in a stochastic manner, such that either AB or CD secretes the protein in each embryo. This stochastic phase is followed by a deterministic phase during which first AB, then CD expresses HRO-WNT-A. When contact between the cells is reduced or eliminated, both AB and CD express HRO-WNT-A simultaneously. Finally, bathing embryos in anti-HRO-WNT-A antibody during first cleavage reduces the adhesion between cells AB and CD. CONCLUSIONS: Our findings show that the stochastic phase of HRO-WNT-A signaling in the two-cell stage of Helobdella is negatively regulated by cell-cell contact and that this early signaling affects cell adhesion without affecting cell fate. We speculate that the primordial function of wnt class genes may have been to regulate cell-cell adhesion and that the nuclear signaling components of the wnt pathway arose later in association with the evolution of diverse cell types.

Animals↗
PubMed2002

Contemporary developmental theory and adolescence: developmental systems and applied developmental science.

PURPOSE: To discuss developmental systems models of human development and explain how they offer a productive frame for research, policies, and programs aimed at understanding adolescents' development and enhancing their health and positive development. Contemporary developmental theory stresses that the multiple levels of organization involved in human life (ranging from biology through culture, the natural and designed ecology, and history) are systemically integrated across ontogeny. Relations within this developmental system are the focus of developmental analysis and application. METHODS: The key features of developmental systems theories are reviewed, and their use for framing scholarship about and applications for improving adolescent development are assessed. RESULTS: We demonstrate the potential of contemporary developmental theory for understanding the character and dynamics of adolescent development and for using this knowledge for the design of effective policies and programs that promote positive youth development. CONCLUSIONS: An adequate and sufficient science of adolescent development, and one that is able to help in the development of successful policies and programs for youth, must integratively study the relations between individuals and contexts in an integrated, systemic, and temporal manner.

Adolescent↗
PubMed1997

Cloning and characterization of a cDNA encoding a protein synthesis initiation factor-2alpha (eIF-2alpha) kinase from Drosophila melanogaster. Homology To yeast GCN2 protein kinase.

Phosphorylation of the alpha subunit of the eukaryotic initiation factor 2 (eIF-2alpha) is one of the best-characterized mechanisms for downregulating protein synthesis in mammalian cells in response to various stress conditions. In Drosophila, such a regulatory mechanism has not been elucidated. We report the molecular cloning and characterization of DGCN2, a Drosophila eIF-2alpha kinase related to yeast GCN2 protein kinase. DGCN2 contains all of the 12 catalytic subdomains characteristic of eukaryotic Ser/Thr protein kinases and the conserved sequence of eIF-2alpha kinases in subdomain V. A large insert of 94 amino acids, which is characteristic of eIF-2alpha kinases, is also present between subdomains IV and V. It is particularly notable that DGCN2 possesses an amino acid sequence related to class II aminoacyl-tRNA synthetases, a unique feature of yeast GCN2 protein kinase. DGCN2 expression is developmentally regulated. During embryogenesis, DGCN2 mRNA is dynamically expressed in several tissues. Interestingly, at later stages this expression becomes restricted to a few cells of the central nervous system. Affinity-purified antibodies, raised against a synthetic peptide based on the predicted DGCN2 sequence, specifically immunoprecipitated an eIF-2alpha kinase activity and recognized an approximately 175 kDa phosphoprotein in Western blots of Drosophila embryo extracts.

Amino Acid Sequence↗
PubMed2001

Thin filaments elongate from their pointed ends during myofibril assembly in Drosophila indirect flight muscle.

Tropomodulin (Tmod) is an actin pointed-end capping protein that regulates actin dynamics at thin filament pointed ends in striated muscle. Although pointed-end capping by Tmod controls thin filament lengths in assembled myofibrils, its role in length specification during de novo myofibril assembly is not established. We used the Drosophila Tmod homologue, sanpodo (spdo), to investigate Tmod's function during muscle development in the indirect flight muscle. SPDO was associated with the pointed ends of elongating thin filaments throughout myofibril assembly. Transient overexpression of SPDO during myofibril assembly irreversibly arrested elongation of preexisting thin filaments. However, the lengths of thin filaments assembled after SPDO levels had declined were normal. Flies with a preponderance of abnormally short thin filaments were unable to fly. We conclude that: (a) thin filaments elongate from their pointed ends during myofibril assembly; (b) pointed ends are dynamically capped at endogenous levels of SPDO so as to allow elongation; (c) a transient increase in SPDO levels during myofibril assembly converts SPDO from a dynamic to a permanent cap; and (d) developmental regulation of pointed-end capping during myofibril assembly is crucial for specification of final thin filament lengths, myofibril structure, and muscle function.

Actin Cytoskeleton↗
PubMed2026

The potential of considering photosynthesis parameters in crop yield breeding by genomic prediction.

To meet the growing demand for agricultural products, optimizing photosynthesis is a promising strategy to improve crop yields. Phenotypic variance in photosynthesis has been observed within or between species. To explore the potential of integrating photosynthetic parameters into crop breeding programs, we explored the genetic variation in photosynthesis by assessing photosynthesis-related parameters across plant development in 631 barley recombinant inbred lines (RILs) from eight HvDRR subpopulations under field conditions. The genetic complexity of these parameters was resolved by analyses of bi-parental and multi-parental quantitative trait loci (QTLs). Finally, we examined the merit of integrating photosynthesis-related parameters in genomic prediction of yield and its components. Significant genotypic variations of the photosynthesis-related parameters were found among the RILs, with their heritability ranging from 0.38 to 0.54. The multiple QTLs and dynamic QTLs for photosynthesis observed across different developmental stages underlined the complexity of the genetics of photosynthesis in barley. The considerably higher percentage of phenotypic variance explained for genomic prediction than multi-parental QTL analysis illustrates that the photosynthesis-related parameters are inherited in a more complex way than classical agronomic traits. Notably, the prediction ability for yield was increased by integrating the photosynthesis-related parameters of some developmental stages into genomic prediction models. Thus, our results suggest a novel perspective on increasing the efficiency of crop breeding programs by integrating photosynthesis-related parameters into prediction models.

Photosynthesis↗