Mechanism and developmental program of immunoglobulin gene rearrangement in mammals.
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Animals↗
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Results for “Developmental programming”
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Developmental programming for retinotectal patterns.
Programming events at stages 28-31 in Xenopus specify the cellular positional information that individual retinal ganglion cells will use to derive theri appropriate locus specificity for assembly of the retinotectal map. The 'programme' that emerges in the stage 31 retina affects the entire ganglion cell population (99 percent of which is generated later) and refers positional information to intraretinal axes (AP and DV) and zero-points. Its expression in intact retinae was not modified by repeated reintroduction into pre-stage 28 orbits, prolonged eye culture in vitro, or severe disruption of the timing and sequence of ganglion cell births or of optic fibre arrivals in the tectum. In contrase, intraretinal reorganizations did not produce major modifications (e.g. after transection, partial ablation, fragment fusion etc.) in the set of locus specificities arising in various retinal regions and, in some instances, in the reference axes themselves. The modified programmes were characteristic of the components undergoing reorganization, but were convergent (many sets of reorganizing components gave a few final patterns); they appeared to involve a stable and rapid reprogramming of certain components by others, in a hierarchical fashion. The remaining experiments focus on the problem of localizing the 'trigger' for the transition from the unspecified to the specified state in the retina at stages 28-31. Specification can occur in vitro, based on reversible AP and DV orientational markers which are present in the pre-stage 28 eye primordium; in heterochromically grafted eyes, specification was neither precipitated nor delayed by altering the stage of the host. Finally, chemical dissection of the differentiating eye primordium confirmed the inference (from Jacobson's [3-H] thymidine labelling kinetics) that a specific gangliogenic precursor cell type exists in the stage 28 retinal neuroepithelium, and suggested that differentiative events in these cells trigger the specification process.
Animals↗
Developmental programs and remediation strategies in schools of nursing.
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Education, Nursing↗
Neural dynamics of speech and language coding: developmental programs, perceptual grouping, and competition for short-term memory.
A computational theory of how an observer parses a speech stream into context-sensitive language representations is described. It is shown how temporal lists of events can be chunked into unitized representations, how perceptual groupings of past item sublists can be reorganized due to information carried by newly occurring items, and how item information and temporal order information are bound together into context-sensitive codes. These language units are emergent properties due to intercellular interactions among large numbers of nerve cells. The controlling neural networks can arise through simple rules of neuronal development: random growth of connections along spatial gradients, activity-dependent self-similar cell growth, and competition for conserved synaptic sites. Within these networks, a spatial frequency analysis of temporally evolving activity patterns leads to competitive masking of inappropriate list encodings in short term memory. The neurons obey membrane equations undergoing shunting recurrent on-center off-surround interactions. Several design principles are embodied by the networks, such as the sequence masking principle, the long-term memory invariance principle, and the principle of self-similar growth.
Auditory Pathways↗
Self-learning packages in staff development.
Potential uses for self-learning packages in the nursing staff development setting include orientation programs, mandatory education programs, developmental programs, and review of infrequently used skills. The staff development educator can use pretest and posttest results obtained from the use of self-learning packages to document intervention with the learner. Benefits for both learners and staff development educators when this teaching strategy is used are described.
Education, Nursing, Continuing↗
Individual program plan goal content in developmental disabilities programs.
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Education of Persons with Intellectual Disabilitie↗
Interdisciplinary early intervention program.
Developmental data were obtained on 40 children with Down's syndrome by an interdisciplinary team during an ongoing early intervention program. Interventive methods are described. Results are compared with available data on children with Down's syndrome who were not in early intervention programs. Comparisons of developmental progress are also made of children begun in the early intervention program before six months of age with those begun after six months of age. Conclusions from the study indicate that early intervention helps the child in earlier attainment of many developmental tasks and enhances functioning of the family unit.
Counseling↗
Effects of Syosset's developmental learning program on self-concept: some preliminary data.
This study investigated the effects of a Developmental Learning Program upon self-concept of 40 children having trouble in school. While preliminary in nature, the results suggest that such a program may have a beneficial effect.
Child↗
A new model of developmental constraints as applied to the Drosophila system.
Von Baer's laws of development observe that an embryo, in the course of its ontogeny, progresses through a series of forms which diverge increasingly from the embryonic forms of related species, and in an evolutionary interpretation, from those of its phylogenetic ancestors. This observation on the relation of phylogeny to ontogeny is explained by Wimsatt's (1986) "Developmental Lock" model of complex generative systems, which proposes that evolution is constrained to alter developmental programs in a manner that usually modifies or adds new complexity to pre-existent developmental functions at positions relatively "downstream" in the causal structure. If the Developmental Lock model is correct, (1) evolution should have resulted in hierarchically ordered developmental programs, and (2) the most important developmental functions in the hierarchy should be ancient. Wimsatt also suggests that developmental functions be analyzed according to a degree property called "generative entrenchment", which replaces the temporal analysis in the traditional formulation of von Baer's laws. Herein, a substantial body of data on Drosophila ontogeny is analyzed according to generative entrenchment, in order to try the effectiveness of this form of analysis, and also to empirically test these two main predictions of the Developmental Lock model. The novel analytic approach proves to be fruitful, both in generating experimental hypotheses and in ordering existing data. Moreover, data concerning the developmental functions discussed here indicate that the order of the Drosophila developmental program conforms to the predictions of Wimsatt's model with few deviations. Explanations of the anomalies are offered, along with proposals for experiments to test some of those explanations.
Animals↗
Developmental intervention program for high-risk premature infants: effects on development and parent-infant interactions.
Developmental follow-up studies have documented that low birth weight infants are at high risk for mental and physical disabilities, despite recent advances in neonatal intensive care. Moreover, parent-infant bonding is hampered by the barriers created by technical equipment. This study evaluated a program of hospital and home-based developmental interventions designed to enhance the development of high-risk, preterm infants and the quality of communication between infants and their caregivers. Treatment and contrast groups consisted of 41 premature infants weighing less than 1800 g at birth. Treatment took a preventive approach, consisting of daily multimodal interventions in-hospital and twice-monthly interventions by child development specialists in the child's home, through 12 months adjusted age. Infants in the contrast group received traditional, remedially oriented care. The Bayley Scales of Infant Development were used to measure mental and psychomotor development, and the Greenspan-Lieberman Observations System (GLOS) was used to analyze the behavioral characteristics of infant-caregiver interactions. Developmental interventions had positive, significant effects on mental development and on the quality of caregiver-infant interactions. Changes in mental development were not independent of changes in the GLOS.
Cognition↗
Aging. Programmed change.
Is aging due to random change or to a developmental program? This fundamental question motivates much research in gerontology and focuses clinical geriatrics research in different directions, as well. If aging changes are random, the prevalence and natural history of disease in the elderly might be unpredictable. Alternatively, if a developmental program continues to operate in late life, physiologic changes could predispose to certain disease or influence therapy in predictable ways. This article argues that the physiology of aging does result from a genetic program that continues to operate in late life.
Aging↗
Granulocyte functions during maturation of human promyelocytic leukemia cells.
Human promyelocytic leukemia cells (HL-60) mature into functional granulocytes in response to in vitro treatment with several classes of chemical agents. Compounds that increase intracellular adenosine 3':5' -cyclic monophosphate induce a modified program of maturation in which the cells demonstrate functional properties characteristic of mature phagocytic cells while remaining morphologically immature. We compared the developmental programs initiated by two well-studied inducers, retinoic acid and dimethyl sulfoxide, with the programs initiated by two inducers known to raise intracellular adenosine 3':5' -cyclic monophosphate; N6, O2-dibutyryl adenosine 3':5' -cyclic monophosphate and the combination of prostaglandin E2 and theophylline. In response to the increase in intracellular adenosine 3':5' -cyclic monophosphate, the cells ceased proliferation, expressed chemotactic receptors and demonstrated stimulated enzyme release within 24 h. Chemotaxis, adherence, NBT reduction and superoxide production appeared by 72 h, although the cells remained unchanged morphologically. A similar developmental program was induced by dimethylsulfoxide, but appearance of the markers was delayed by 48 h. Expression of these markers was delayed and incomplete in response to retinoic acid.
Bucladesine↗
Multivariate analyses of cognitive and cognitive style variables based on hemisphere specialization theory predictive of success in a college developmental studies program.
Right and left cerebral hemisphere and limbic scores derived from the Herrmann Brain Dominance Profile, Scholastic Aptitude Test Verbal and Mathematics scores, and High School Grade Point Average were correlated with grades in college developmental courses in reading, English, and mathematics for 146 students. Pearson correlations ranged from -.27 to .42. Multiple correlations with seven predictors ranged from .45 to .55, and from .14 to .37 for the profile scores alone. Discriminant analyses yielded hit-rates (predictive of classification of success and failure/actual classification) of 69%/72% in Reading, 76%/75% in English, and 66%/71% in Mathematics.
Achievement↗
Children at risk: perinatal events, developmental delays and the effects of a developmental stimulation program.
This paper reports the findings of two studies done between 1977 and 1981 in the Philippines. The first study examined the performance of 911 children, with histories of perinatal risk events, on a restandardized Philippine (Metro-Manila) version of the Denver Developmental Screening Test (DDST) which was developed in 1980. This study established that the children performed significantly below Philippine norms. A second study, cognizant of the findings of the first, introduced nursing interventions designed to address some needs of preterm infants and their mothers. Findings suggest that development stimulation can significantly improve the developmental status of preterm infants.
Child↗
Parasite regulation of host insect metamorphosis: a new form of regulation in pseudoparasitized larvae of Trichoplusia ni.
When eggs of Trichoplusia ni (lepidoptera) are stung by a parasitic wasp, Chelonus sp., the developing host larvae precociously initiate metamorphosis ten days later. Precocious initiation of metamorphosis occurs even in 'pseudoparasitized' stung hosts which contain no living parasites at the time of symptoms of host regulation by the parasite. In feeding, penultimate instar, pseudoparasitized hosts, the corpora allata activity, hemolymph juvenile hormone esterase activity, in vivo rates of juvenile hormone metabolism and changes in hemolymph protein composition all follow the pattern of the normal last instar. This and other evidence suggests the entire developmental pattern of the last larval instar is precociously expressed in penultimate instar, pseudoparasitized hosts. The cause of precocious expression of the developmental program leading to metamorphosis is a significant decrease in the critical size parameter that, in normal larvae, signals attainment of the last instar. The induction, in preultimate instar larvae, of the entire feeding stage developmental program leading to metamorphic commitment, using either biochemical, surgical or parasitic experimental probes, has not been previously reported. The results have important implications for the study of host-parasite endocrine interaction, of normal insect metamorphosis and even of human puberty.
Animals↗
Positioning of gene products during Caulobacter cell differentiation.
Caulobacter crescentus has one of the simplest known developmental programs that exhibits both temporal and spatial organization. A hallmark of the Caulobacter cell cycle is that the progeny cells that result from each cell division differ from one another with respect to structure and developmental program. The process of establishing asymmetry prior to cell division requires that a number of gene products be targeted to a pole of the predivisional cell and consequently segregated to one of the two progeny. Several products involved in flagellar biogenesis and the chemotaxis machinery are segregated to the swarmer cell. Evidence suggests that the protein product of some fla and che genes is targeted to the incipient swarmer cell pole. In the case of other flagellar genes, it is the mRNA that is apparently segregated to the swarmer cell. Two heat shock proteins, DnaK and Lon are specifically segregated to the progeny stalked cell.
Bacterial Proteins↗
Characterization of genes which are deactivated upon the onset of development in Dictyostelium discoideum.
We have identified and begun characterizations of the differential expression of 15 genes whose corresponding mRNA levels decrease during the preaggregative period of the developmental program of Dictyostelium discoideum. Upon the onset of development, the mRNAs decrease from 5- to 1000-fold over the first 8 hr. The rates of loss of each mRNA were similar to one another but distinct, and the decreases were dependent on progress through the developmental program. One exception to this dependency was observed, and the decrease in this mRNA was dependent on the absolute time after initiation of development instead of progress through development. With two exceptions, the decreases in mRNA levels were dependent on developmental conditions and were not seen when cells were shaken in starvation buffer. When the polysomal distributions of each species were examined, three classes were found: most showed no significant shifts off of polysomes upon initiation of development, two were characterized by a 20% shift to nonpolysomal RNA fractions upon development, and two gave a 40-50% shift. Collectively, these characterizations reveal differences in behavior which suggest that deactivation of genes upon initiation of development in Dictyostelium involves more than one regulatory pathway.
Cloning, Molecular↗
A detailed developmental and structural study of the transcriptional effects of insertion of the Copia transposon into the white locus of Drosophila melanogaster.
The copia insertion responsible for the wa mutation is 3' to the white promotor and in the same transcriptional orientation as white. First, we have analyzed the effects of the wa copia insertion on levels of polyadenylated white transcripts and find large, developmentally programmed effects. Second, we have isolated and sequenced an LTR-excision event involving the copia insertion at wa. This represents the first documented case of an LTR-excision event in Drosophila. This single copia LTR has developmentally programmed effects on white transcript levels qualitatively similar to the intact copia element. Third, we have characterized the structures of white transcripts from wa. We find polyadenylated white transcripts apparently having 3' termini in or near the 3' LTR of the wa copia insertion, as has been reported in limited studies of wa transcription in adults by others. These earlier studies also revealed wa transcripts apparently corresponding to polyadenylated terminus formation in the 5' LTR of the copia transposon; however, our more detailed studies reveal that these transcripts probably have other origins and that little, if any, polyadenylated terminus formation for white transcripts occurs in the 5' LTR of the wa copia insertion. Moreover, we find no polyadenylated terminus formation for white transcripts occurring in the single LTR of the wa LTR-excision product. Fourth, we find that each of three mutant alleles at su(wa) produces elevated levels of several classes of RNAs apparently corresponding to transcriptional readthrough of the wa copia transposon. Elevated levels of one presumptive readthrough transcript were observed previously in one su(wa) mutant strain. Fifth, we have confirmed the existence of a transcript initiated in the 3' LTR of the wa copia insertion and find the levels of this transcript to be strongly influenced by developmental stage and genetic background. Lastly, we have analyzed white transcripts produced by the whd81b11 allele, which carries an insertion of copia in the opposite transcriptional orientation and in a different position than the wa copia insertion. In contrast to the wa copia insertion allele, the whd81b11 allele produces polyadenylated white transcript levels very similar to the w+ case at the stages examined. Moreover, the whd81b11 copia element apparently produced polyadenylated terminus formation in white transcripts and we observe no effect of the allelic state of su(wa) on apparent readthrough of this stop site.(ABSTRACT TRUNCATED AT 400 WORDS)
Alleles↗