[Proceedings of the IV National Population Workshop: Ontogenesis and Population. Moscow, May 18-19, 2001].
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Animals↗
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Results for “developmental dynamics”
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Maturation of EPSCs and intrinsic membrane properties enhances precision at a cerebellar synapse.
The timing of action potentials is an important determinant of information coding in the brain. The shape of the EPSP has a key influence on the temporal precision of spike generation. Here we use dynamic clamp recording and passive neuronal models to study how developmental changes in synaptic conductance waveform and intrinsic membrane properties combine to affect the EPSP and action potential generation in cerebellar granule cells. We recorded EPSCs at newly formed and mature mossy fiber-granule cell synapses. Both quantal and evoked currents showed a marked speeding of the AMPA receptor-mediated component. We also found evidence for age- and activity-dependent changes in the involvement of NMDA receptors. Although AMPA and NMDA receptors contributed to quantal EPSCs at immature synapses, multiquantal release was required to activate NMDA receptors at mature synapses, suggesting a developmental redistribution of NMDA receptors. These changes in the synaptic conductance waveform result in a faster rising EPSP and reduced spike latency in mature granule cells. Mature granule cells also have a significantly decreased input resistance, contributing to a faster decaying EPSP and a reduced spike jitter. We suggest that these concurrent developmental changes, which increase the temporal precision of EPSP-spike coupling, will increase the fidelity with which sensory information is processed within the input layer of the cerebellar cortex.
Action Potentials↗
Environmental origins of sexually selected variation and a critique of the fluctuating asymmetry-sexual selection hypothesis.
Identifying sources of phenotypic variability in secondary sexual traits is critical for understanding their signaling properties, role in sexual selection, and for predicting their evolutionary dynamics. The present study tests for the effects of genotype, developmental temperature, and their interaction, on size and fluctuating asymmetry of the male sex comb, a secondary sexual character, in Drosophila bipectinata Duda. Both the size and symmetry of elements of the sex comb have been shown previously to be under sexual selection in a natural population in northeastern Australia. Two independent reciprocal crosses were conducted at 25 degrees and 29 degrees C between genetic lines extracted from this population that differed in the size of the first (TC1) and third (TC3) comb segments. These temperatures are within the documented range experienced by the species in nature. Additive and dominance genetic effects were detected for TC1, whereas additive genetic, and Y-chromosomal effects were detected for TC3. TC2 and TC3 decreased sharply with increasing temperature, by 10% and 22%, respectively. In contrast, positional fluctuating asymmetry (PFA) significantly increased with temperature, by up to 38%. The results (1) document an important source of environmental variance in a sexual ornament expected to reduce trait heritability in field populations, and thus act to attenuate response to sexual selection, (2) suggest that variation in ornament size reflects differences in male condition; and (3) support the general hypothesis that asymmetry in a sexual ornament is indicative of developmental instability arising from environmental stress. The "environmental heterogeneity" (EH) hypothesis is proposed, and supportive evidence for it presented, to explain negative size-FA correlations in natural populations. Data and theory challenge the use of negative size-FA correlations observed in nature to support the FA-sexual selection hypothesis, which posits that such correlations are driven by differences in genetic quality among individuals.
Analysis of Variance↗
Tetralogy of Fallot.
This article has discussed TOF, its occurrence, physiology, medical interventions and nursing implications. In its classic form, TOF consists of four anatomical aberrations: a large VSD, pulmonic stenosis, dextroposition of the aorta, and right ventricular hypertrophy. Surgical palliation versus primary intracardiac repair is a continuing discussion in medical literature. Children who have undergone intracardiac repair for TOF have an excellent prognosis for late survival, near 90% 10 years after repair. Nursing responsibilities in the care of the newborn diagnosed as having TOF encompass the well-being of the newborn as well as the family. Palliation increases pulmonary arterial flow, thus decreasing cyanosis and promoting measurable clinical improvement in the infant. Preparation of the family and child for surgery involves completing a baseline assessment of family dynamics, diagnosing stressors, composing objectives, carrying out interventions focused on developmental ability, and evaluating the effectiveness of the nursing process. Maintaining the physical and emotional integrity of a child just out of the operating room is a challenge. Parental support is important to the young child's feelings of security while hospitalized.
Arteriovenous Shunt, Surgical↗
[Dynamics of the development of the bronchi in childhood and radiographic analysis of the number and the site of their origin with particular consideration of developmental variations. I].
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Adolescent↗
Morphing: a new graphics tool for animating confocal images.
The application of morphing to the display of developmental processes is described. This new graphics tool imparts the dynamic aspects of time-lapse microscopy to a series of fixed and stained images of a developing system. The technique is illustrated using confocal images of wing imaginal discs of Drosophila. It is anticipated that morphing can be applied not only to the display and analysis of developing systems but also to the elucidation of evolutionary relationships between species and to comparative anatomy.
Animals↗
The effect of fasting at different ages on growth and tissue dynamics in the small intestine of the young chick.
The small intestines of hatching chicks undergo rapid developmental changes in the immediate post-hatch period when the birds are making the transition from endogenous nutrient supply from yolk to dependence on exogenous feed. This transition usually only begins 48 h or more after hatching, owing to logistical considerations of production. The effects of fasting for 48 h at different times during this critical period on small intestinal development and enterocyte dynamics were examined by morphometric determinations and use of staining for proliferative-cell nuclear antigen and 5-bromo-2-deoxyuridine. The effects of fasting were specific to both time of fasting and the intestinal segment examined. Decreased development was found in the duodenum and jejunum, but was less apparent in the ileum. Fasting between 0 and 48 h decreased crypt size in the duodenum and jejunum, the number of crypts per villus, crypt proliferation, villus area and the rate of enterocyte migration. Fasting at later times resulted in smaller effects, although the jejunum appeared to be the most sensitive of the intestinal segments. Growth was correlated with the number of cells in the crypts, the number of cells along the villus and the segment surface area. The common practice whereby feed is first available to chicks more than 48 h post-hatch may depress subsequent development.
Animals↗
Fantasy or structural defect? The borderline dilemma as viewed from analysis of an experience of nonhumanness.
The experience of nonhumanness, a crucial aspect of the phenomenal self of borderline states, is studied in two cases to test assumptions concerning the application of the classic ego-psychological or object-relations and self-psychological models. Are these experiences to be seen as fantasy and treated as manifest content, with dynamically active unconscious conflict and meaning, requiring interpretation, or as a developmental arrest in which structural disturbances are ameliorated through clarifying and empathic interventions? The first case is of a patient with a neurotic depression and hysterical and obsessional character traits, treated in a classic psychoanalysis. Even though dyadic oral and anal fantasies were strongly in evidence, the ego was well integrated. The second case is of a severe borderline patient who showed depressive panic and agoraphobia. Her major ego disturbances, poorly integrated and differentiated self- and object representations, and primitive defenses prevented effective psychoanalytically oriented treatment. Interventions were used to consolidate self-representations, internalize tension-regulating structures, promote adaptive ego functions and reality testing. These clarifications were necessary to move the patient to where she could tolerate facing unconscious dynamic conflicts. Only at that point could repression be lifted, memory emerge, and interpretation be utilized.
Adult↗
[The importance of the phenomenom "imagination" in the scientific work of Werner Janzarik].
This paper in three parts and conclusion begins with the description of Janzarik's progression of thought, which originates in the narrowing of the gap between Jasper's descriptive phenomenology and anthropological phenomenology with its interpretive elements. Janzarik's structural-dynamic psychopathological approach has grown and differentiated from originally relatively narrow psychopathological questions to become an anthropology which aims to describe human assumptions concerning individual development/growth. The experience dimension is the focus, without suppressing interdisciplinary, objective findings, such as the inclusion of ethology. The mere clinical reconstruction of mental processes with all its heuristic risk was characterised by Janzarik as 'pure psychopathology'. In the section concerning structure and representation and their dependence on affect dynamic, we will emphasise the procedural nature of Janzarik's anthropology regarding developmental processes and its relationship to the philosopher Plessner's work in philosophy. The significance of the imagination in Janzarik's work contrasts to other philosophers who regard the imagination as ontological weakness, a deficiency, non-real, Janzarik, like Kant, sees the imagination as a constituent of reality. This will be exemplified in the characterisation of the mental field concerning the structural-dynamic model, the psychopathology of delusion as well as the oneiroid psychopathology. Finally the connection between autopraxis, Janzarik's core concept for the spontaneity of incidences and memory functions, and imagination will be described, which to a certain extent emphasises the working character of imagination for the flow of controlled mental activity. We will finish with the observation that Janzarik's work especially stresses experience and thus also the patient's individuality.
Anthropology↗
A connectionist model of development.
We present a phenomenological modeling framework for development. Our purpose is to provide a systematic method for discovering and expressing correlations in experimental data on gene expression and other developmental processes. The modeling framework is based on a connectionist or "neural net" dynamics for biochemical regulators, coupled to "grammatical rules" which describe certain features of the birth, growth, and death of cells, synapses and other biological entities. We outline how spatial geometry can be included, although this part of the model is not complete. As an example of the application of our results to a specific biological system, we show in detail how to derive a rigorously testable model of the network of segmentation genes operating in the blastoderm of Drosophila. To further illustrate our methods, we sketch how they could be applied to two other important developmental processes: cell cycle control and cell-cell induction. We also present a simple biochemical model leading to our assumed connectionist dynamics which shows that the dynamics used is at least compatible with known chemical mechanisms.
Animals↗
Qualitative changes in dynamic tripod grip between seven and 14 years of age.
The dynamic tripod grip during handwriting was examined among seven- to 14-year-old children. Four components were measured: (a) degree of index-finger flexion; (b) degree of forearm pronation/supination; (c) number of fingers used on the pencil shaft; and (d) thumb and forefinger opposition. Developmental trends were identified for measures (a) and (b), suggesting refinement of the dynamic tripod grip with age.
Adolescent↗
Community dynamics: what happens when we rerun the tape?
The role of historical events, such as disturbances, in producing alternative developmental outcomes in forest structure has long been debated. Diversity in the assemblages of coexisting species is one measure of alternative outcomes of succession. The intermediate disturbance hypothesis proposes that a moderate disturbance level produces the highest levels of species diversity. Here, we use an agent-based model of forest development under a gradient of lightning strike frequency to analyse long-term dynamics of species coexistence in a multi-species forest. The configurations of species that result from disturbance dynamics reflect the interactions between life-history characteristics of the species and disturbance characteristics. Model results suggest that low levels of disturbance lead to highly ordered landscapes which exclude fire and are captured by late successional species. High levels of disturbance lead to oscillation between domination by early successional species and large disturbances. At intermediate levels of disturbance, the forest displays the broadest array of developmental pathways, highest entropy as measured by Shannon's index of diversity, and critical slowing near steady states. Long transients at intermediate regimes may reflect the working out of closely balanced constraints of competition between species with varying strategic adaptations to disturbance. Intermediate disturbance levels also result in the greatest number of alternative diversity configurations as outcomes of succession, reflecting an unpredictable and nonequilibrium forest dynamic.
Animals↗
NADPH diaphorase is developmentally regulated in rat olfactory epithelium.
In vertebrate olfactory receptor neurons, NO synthase (NOS) has been detected in embryonic and early postnatal stages. However, expression of the enzyme in the mature epithelium is still controversial. We analyzed the developmental expression pattern of the histochemical NOS-marker NADPH diaphorase (NADPHd) in the olfactory epithelium of young rats. NADPHd was expressed in a small subset of olfactory receptor neurons as early as P0. Between P0 and P24 the number of labeled neurons increased 10-fold, stabilizing thereafter. Whereas NADPHd was generally found in the somata, a transitory dendritic expression was observed between P2 and P5. This dynamic postnatal regulation of the cellular distribution of NADPHd appears to reflect developmental processes within the olfactory epithelium.
Animals↗
Artificial indoor streams as a method to investigate the impact of chemicals on lotic communities.
The potential hazard of chemicals on aquatic communities are generally evaluated by standardised single-species bioassays. Safety assessment is based on results gained from organisms adapted to lentic systems and biological interactions in ecosystems are neglected. While lotic communities are often at first in contact with chemicals, it is astonishing that microcosms with lentic communities are mainly used as a bridge between laboratory bioassays and outdoor aquatic systems. Hence, we established five artificial indoor streams to simulate abiotic factors of small rivers. The closed-circuit system was filled with nutrients added to tap water. Washed pebbles were used as sediment. The dynamics of a simple biocoenoses consisting of aufwuchs, Lumbriculus variegatus Asellus aquaticus and Gammarus fossarum was investigated. The dynamic of aufwuchs and periphyton was determined as dry weight and chlorophyll-a, respectively and qualitatively by pigment pattern. The abundance of different developmental stages of L. variegatus was determined at the end of the experiment as well as the population dynamics of G. fossarum and A. aquaticus. Survival rates of gammarids and juveniles per female were investigated and data were used for modelling the population dynamics. The experiment was carried out to investigate the performance of the established artificial streams and the developed approaches to investigate effects of chemicals on a basic lotic community. The prime reason to establish this approach was to close a gap between complex artificial stream systems and laboratory single species tests to assess the impact of chemicals on the aquatic environment.
Animals↗
A change in conformational dynamics underlies the activation of Eph receptor tyrosine kinases.
Eph receptor tyrosine kinases (RTKs) mediate numerous developmental processes. Their activity is regulated by auto-phosphorylation on two tyrosines within the juxtamembrane segment (JMS) immediately N-terminal to the kinase domain (KD). Here, we probe the molecular details of Eph kinase activation through mutational analysis, X-ray crystallography and NMR spectroscopy on auto-inhibited and active EphB2 and EphA4 fragments. We show that a Tyr750Ala gain-of-function mutation in the KD and JMS phosphorylation independently induce disorder of the JMS and its dissociation from the KD. Our X-ray analyses demonstrate that this occurs without major conformational changes to the KD and with only partial ordering of the KD activation segment. However, conformational exchange for helix alphaC in the N-terminal KD lobe and for the activation segment, coupled with increased inter-lobe dynamics, is observed upon kinase activation in our NMR analyses. Overall, our results suggest that a change in inter-lobe dynamics and the sampling of catalytically competent conformations for helix alphaC and the activation segment rather than a transition to a static active conformation underlies Eph RTK activation.
Amino Acid Substitution↗
Comparison of molecular mechanisms mediating cell contact phenomena in model developmental systems: an exploration of universality.
Are there universal molecular mechanisms associated with cell contact phenomena during metazoan ontogenesis? Comparison of adhesion systems in disparate model systems indicates the existence of unifying principles. Requirements for multicellularity are (a) the construction of three-dimensional structures involving a crucial balance between adhesiveness and motility; and (b) the establishment of integration at molecular, cellular, tissue, and organismal levels of organization. Mechanisms for (i) cell-cell and cell-substrate adhesion, (ii) cell movement, (iii) cell-cell communication, (iv) cellular responses, (v) regulation of these processes, and (vi) their integration with patterning, growth, and other developmental processes are all crucial to metazoan development, and must have been present for the emergence and radiation of Metazoa. The principal unifying themes of this review are the dynamics and regulation of cell contact phenomena. Our knowledge of the dynamic molecular mechanisms underlying cell contact phenomena remains fragmentary. Here we examine the molecular bases of cell contact phenomena using extant model developmental systems (representing a wide range of phyla) including the simplest i.e. sponges, and the eukaryotic protist Dictyostelium discoideum, the more complex Drosophila melanogaster, and vertebrate systems. We discuss cell contact phenomena in a broad developmental context. The molecular language of cell contact phenomena is complex; it involves a plethora of structurally and functionally diverse molecules, and diverse modes of intermolecular interactions mediated by protein and/or carbohydrate moieties. Reasons for this are presumably the necessity for a high degree of specificity of intermolecular interactions, the requirement for a multitude of different signals, and the apparent requirement for an increasingly large repertoire of cell contact molecules in more complex developmental systems, such as the developing vertebrate nervous system. However, comparison of molecular models for dynamic adhesion in sponges and in vertebrates indicates that, in spite of significant differences in the details of the way specific cell-cell adhesion is mediated, similar principles are involved in the mechanisms employed by members of disparate phyla. Universal requirements are likely to include (a) rapidly reversible intermolecular interactions; (b) low-affinity intermolecular interactions with fast on-off rates; (c) the compounding of multiple intermolecular interactions; (d) associated regulatory signalling systems. The apparent widespread employment of molecular mechanisms involving cadherin-like cell adhesion molecules suggests the fundamental importance of cadherin function during development, particularly in epithelial morphogenesis, cell sorting, and segregation of cells.
Animals↗
Developmental regulation of action potential-induced Ca2+ entry in neocortical neurons.
Intracellular calcium plays a critical role in the regulation of membrane excitability, synaptic integration and synaptic plasticity. Using whole-cell recording and calcium imaging, we investigated intracellular calcium dynamics in apical dendrites of layer V pyramidal cells in the immature rat neocortex. Dendritic calcium increases induced by action potentials were only small on postnatal days 4-6 (P4-6), then underwent a gradual enhancement during the second post-natal week and were 2- to 3-fold larger on P16-18 than on P4-6. At P15-18 there were no significant differences in the calcium increases among the three subclasses of layer V pyramidal neurons: adapting regular spiking (RS), non-adapting RS and intrinsically bursting (IB) neurons. Developmental regulation of dendritic calcium dynamics may be crucial for functional maturation of the neocortex.
Action Potentials↗
The diagnostic value of the Bene-Anthony Family Relations Test.
The aim of this study was to assess whether interning psychologists, who used the Bene-Anthony as an evaluation technique in the psychotherapeutic treatment of their clients, were of the opinion that the test results deepened their insight into the nature of their clients' family dynamics. Subjects were 32 children, ages 4 to 16 years, who were referred for evaluation for the presence of emotional or specific developmental disorders. The interns were of the opinion the Bene-Anthony significantly contributed to their understanding of the family dynamics. Family relationships appeared to be more complex after the application of the test than they seemed before, and the test also clarified the negative nature of the family relationships. The Bene-Anthony may be effectively used for evaluation of family systems in which dysfunctionality occurs.
Adolescent↗