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At least 1,729 records · Page 96Linked to original sources
PubMed1998

Control of gene expression in Xenopus early development.

We examine the control of gene expression before and through the MBT in Xenopus laevis. The generalized repression of transcription that occurs before the midblastula transition (MBT) is regulated by a dynamic competition between chromatin and transcription complex assembly. Conditions favoring the access of basal factors (TBP) or transactivators can overcome this transcriptional repression. Changes in DNase I hypersensitivity patterns of the chromatin during early development show that it is more accessible to DNase I before the MBT (and by extension to other DNA interacting proteins) than after the MBT. We also show that at the level of genomic domains, organization of the chromatin matrix attachment sites is random before MBT. We propose that these three components, chromatin domain structure, DNA accessibility, and the transcription complex-chromatin dynamic competition, combine to regulate transcription in the embryo before and through the MBT.

Animals↗
PubMed2006

Eph receptors and their ephrin ligands are expressed in developing mouse pancreas.

Pancreas development involves branching morphogenesis concomitantly to differentiation of endocrine, exocrine and ductal cell types from a single population of pancreatic precursors. These processes depend on many signals and factors that also control development of the central nervous system. In the latter, Eph receptors and their class-A (GPI-anchored) and class-B (transmembrane) ephrin ligands control cell migration and axon-pathfinding, help establish regional patterns and act as labels for cell positioning. This raised the question as to whether and where Ephs and ephrins are expressed during pancreas development. Here we have identified the Eph and ephrin genes that are expressed in mouse embryonic pancreas, as detected by RT-PCR analysis. In situ hybridization experiments showed that Ephs and ephrins are mainly expressed in the burgeoning structures of the epithelium which differentiate into exocrine acini. Binding experiments on whole pancreas demonstrated the presence of functional Eph receptors. They showed that EphBs are expressed by the pancreatic epithelium at embryonic day (e) 12.5 and that, from e14.5 on, Ephs of both classes are expressed by the pancreatic epithelium and then become restricted to developing acini. We conclude that specific members of the Eph/ephrin family are expressed in embryonic pancreas according to a dynamic temporal and regional pattern.

Animals↗
PubMed2000

Vasa protein expression and localization in the zebrafish.

Primordial germ cell (PGC) development in the zebrafish is poorly understood. The expression of vasa RNA, the only molecular marker so far found to be expressed in fish PGCs, suggests its function in the establishment of the germline. The protein product of vasa is present throughout the life cycle in the germline of Drosophila, Caenorhabditis and Xenopus. The expression pattern of the Vasa protein in zebrafish, is still unresolved. We generated an anti-Vasa polyclonal antibody and show that it is maternally expressed initially throughout the embryo. Interestingly, from the two-cell- to the 1000-cell stage the protein is highly concentrated in two 'dots' near the center of the blastomeres and as such remains longest detectable in the animal pole blastomeres. The first distinct cell-specific expression occurs at 60% epiboly on one side of the blastoderm margin. The Vasa protein in the PGCs is organized in a subcellular granular-like conformation which is dynamic throughout development.

Animals↗
PubMed1999

The psychoanalytic treatment of a child with deviational development.

This paper presents the analysis of Peter, a five-year-old boy with compromised ego functions including difficulties in maintaining stable internalized object representations. Despite these serious problems, which are often seen as contraindicating analysis, a predominantly traditional psychoanalytic position emphasizing dynamic interpretations was utilized. Detailed clinical material is presented to demonstrate the effectiveness of this approach in facilitating therapeutic changes in Peter.

Child, Preschool↗
PubMed1990

Health and social antecedents of relocation in rural elderly persons.

Sociodemographic, health, and psychobehavioral correlates of anticipated and actual relocation were examined in a geographically-defined rural elderly population (N = 3097). Intent to move was associated with higher levels of depressive symptoms. Of those responding, 4.8 percent moved between the baseline and one-year follow-up interviews. Disproportionally high numbers of women, persons over 84 years of age, those who lived alone, persons with lower incomes, and the less educated made noninstitutional moves. Actual noninstitutional relocation was associated with poorer physical functional status, poorer self-perceived health status, higher levels of depressive symptomatology and anxiety, and poorer life satisfaction at baseline. Death of spouse, marriage of offspring, and having someone move in with the respondent were associated with noninstitutional relocation, but retirement was not. The outcomes are generally consistent with Litwak and Longino's (1987) developmental model of relocation among elderly persons.

Aged↗
PubMed1998

Commissureless endocytosis is correlated with initiation of neuromuscular synaptogenesis.

We show that the Commissureless (COMM) transmembrane protein is required at neuromuscular synaptogenesis. All muscles in the Drosophila embryo express COMM during the period of motoneuron-muscle interaction. It is endocytosed into muscles before synaptogenesis. In comm loss-of-function mutants, motoneuron growth cones fail to initiate synaptogenesis at target muscles. This stall phenotype is rescued by supplying wild-type COMM to the muscles. Cytoplasmically truncated COMM protein fails to internalize. Expressing this mutant protein in muscles phenocopies the synaptogenesis defects of comm mutants. Thus, synaptogenesis initiation is positively correlated with endocytosis of COMM in postsynaptic muscle cells. We propose that COMM is an essential part of the dynamic cell surface remodeling needed by postsynaptic cells in coordinating synaptogenesis initiation.

Animals↗
PubMed1994

[Molecular cloning and expression of homeobox-containing genes during hard tissue development].

Although much is known about the hormonal regulation of hard tissue development, much less is known about the nuclear regulatory molecules that affect the process. Homeobox-containing genes are thought to encode DNA-binding transcriptional factors which control the expression of other genes. In this study, molecular cloning of Msx homeobox-containing genes from a bovine odontoblast library and a human dental pulp-derived cells library was performed, and also the expression of mRNAs for Hox and Msx homeobox-containing genes during ectopic bone formation induced by BMP was investigated. Screening of a bovine odontoblast cDNA library and a human dental pulp-derived cells library with murine Msx-1 and Msx-2 cDNA probes led to the isolation of several positive clones. All of the clones from a bovine odontoblast library encoded the bovine counterpart for human MSX-1. All of the clones from a human dental pulp-derived cells library encoded the human counterpart for murine Msx-2. Northern blot analysis probed with a human MSX-2 cDNA indicated the expression of 2.2kb and 1.2kb mRNA in human dental pulp-derived cells. Polymerase chain reaction (PCR)-based analysis in the BMP-implanted tissue revealed that nine rat homologues of Hox homeobox-containing genes were expressed in the early cell migration stage and that two Msx genes were expressed in the cartilage and bone differentiation stages. The PCR study provided evidence of dynamic changes in the BMP-induced homeobox gene expression.

Amino Acid Sequence↗
PubMed1999

Molecular cloning and developmental expression of a zebrafish axonal glycoprotein similar to TAG-1.

TAG-1 is a mammalian cell adhesion molecule of the immunoglobulin superfamily that is expressed transiently by a subset of neurons and serves as a fertile substrate for neurite outgrowth in vitro (Furley, A.H., Morton, S.B., Manalo, D., Karagogeos, S., Dodd, H., Jessell, T.M., 1990 The axonal glycoprotein TAG-1 is an immunoglobulin superfamily member with neurite outgrowth promoting activity. Cell 61, 157-170). In order to examine the in vivo function of this molecule, we have cloned a zebrafish tag1-like cDNA and analyzed its expression patterns. tag1 Is expressed transiently by specific subsets of neurons when they are projecting their axons or when they are migrating. The specific and dynamic pattern of expression of zebrafish tag1 is consistent with its proposed role in axon guidance and cell migration.

Animals↗
PubMed2000

Neuronal degeneration and reorganization: a mutual principle in pathological and in healthy interactions of limbic and prefrontal circuits.

Based on developmental principles and insights from animal research about neuroplasticity in cell assemblies, this article is to propose a view of plasticity that promotes a link between hippocampal and prefrontal structure and function. Both the mitotic activity (counting of BrdU-labeled cells) in hippocampal dentatus and the maturation of dopamine fibres (quantitative immunochemistry of mesoprefrontal projection) in the prefrontal cortex proved to be a measurable combination for investigating the complex chain of events that relate activity dependent neuroplasticity to normal as well as to pathological maturational processes. With our animal model we demonstrate that both rearing conditions and neuroactive substances can effectively interfere with developmental plasticity and induce a malfunctional adaptation of prefrontal structures and neurotransmitter systems (dopamine, GABA). In the hippocampal dentatus, where ontogenetic plasticity proved to be preserved by continued neuro- and synaptogenesis, serious damage can be internalized without simultaneous disruption of neural dynamics offering an approach to reverse dysfunctional reorganization in the prefrontal cortex.

Animals↗
PubMed2006

Protein-protein interactions and nuclear trafficking of coat protein and betaC1 protein associated with Bhendi yellow vein mosaic disease.

Bhendi yellow vein mosaic disease (BYVMD) is caused by a complex consisting of a monopartite begomovirus BYVMV and a satellite DNA beta component. BYVMV represents a new member of the emerging group of monopartite begomoviruses requiring a satellite component for symptom induction. Here we report the results of the transient expression of green fluorescent protein (GFP) fused with the betaC1 and coat protein (CP) coding regions, in the epidermal cells of Nicotiana benthamiana. GFPCP was found to be targeted into the nucleus whereas GFPbetaC1 was localized towards the periphery of the cell. The sub-cellular localization of the betaC1 protein has been compared with that of the CP in yeast cells using a genetic system for detection of protein nuclear import and export. Expression of betaC1 ORF in transgenic N. benthamiana under the control of the Cauliflower mosaic virus 35S promoter produced severe developmental abnormalities in the plant, like distorted stem, leaves and stunting of the plant. We also present the results on the interaction of CP and betaC1 proteins using yeast two hybrid analysis, suggesting a collaborative role in the inter- and intracellular dynamics of BYVMD.

Active Transport, Cell Nucleus↗
PubMed2006

Inhibition of kinesin motor proteins by adociasulfate-2.

Kinesin motor proteins are involved in cell division and intracellular transport of vesicles and organelles, and as such, they play a role in neurological disease, cancer, and developmental disorders. Inhibitors of kinesin would be valuable as probes of cell physiology and as potential therapeutics. Adociasulfate-2 (AS-2) is the only known natural product inhibitor of kinesins, but its mechanism of action is unknown. We utilized kinetic studies, dynamic light scattering, and transmission electron microscopy to investigate the inhibitory action of AS-2. Our data suggest that AS-2 is not a classical 1:1 inhibitor. Instead, a rodlike aggregate that mimics microtubules is complexed with kinesin and inhibits its ATPase activity. An intriguing implication of this hypothesis is that aggregates of a chiral natural product can have interesting and biologically relevant properties. This mode of action might represent one way in which a small molecule can disrupt a protein-protein interaction.

Kinesins↗
PubMed1982

Cell adhesion molecules in early chicken embryogenesis.

N-CAM, the neural cell adhesion molecule, has been found at a number of regions in the early (1-5 days) chicken embryo by fluorescent antibody techniques. These regions appear to be those concerned with induction of the primary developmental axis (neural plate, neural tube, notochord, somites) or those in which later inductive events occur (neural crest cells, optic, otic, and pharyngeal placodes, cardiac mesoderm, mesonephric primordium, limb buds). The staining patterns in the latter group of regions are highly dynamic and transient and are limited to the epithelial components of the placodes and to the precursors of mesonephric tubules. In neural crest cells, N-CAM appears early, disappears during migration of the cells on fibronectin, and reappears at sites where ganglia are formed. In other regions of the nervous system, particularly those related directly to the neural tube, the N-CAM molecule is stained at all stages. The results raise the possibility that adhesion mediated by N-CAM plays a primary role in early embryogenesis as well as in later histogenesis.

Brain↗
PubMed2000

Transmission of the human mitochondrial genome.

The segregation and transmission of mitochondrial genomes in humans are complicated processes, but are particularly important for understanding the inheritance and clinical abnormalities of mitochondrial disorders. This review describes three aspects of mitochondrial genetics. First, that the segregation and transmission of mitochondrial (mt)DNA molecules are likely to be determined by their physical association within the organelles and by the dynamics of mitochondrial structure and subcellular organization. Second, that the transmission of heteroplasmic mtDNA sequence changes from one generation to the next often involves rapid shifts in allele frequency. For >20 years, the standard explanation has been that there is a developmental bottleneck in which, at some stage of oogenesis, there is a reduction in the effective number of mitochondrial units of inheritance. The third aspect is that ongoing analyses of the segregation and transmission of pathogenic mtDNA mutations indicate the operation of multiple genetic processes. Thus, the segregation and transmission of mtDNA mutations occurs predominantly, but not exclusively, under conditions of random genetic drift. However, there is also evidence for bias due to incomplete ascertainment of pedigrees and for negative selection of pathogenic mutations in rapidly dividing somatic tissues such as the white blood cell population.

Chromosome Segregation↗
PubMed2025

The functional organization of chromosome territories in single nuclei during zygotic genome activation.

Chromosome territories (CTs) are intricately organized and regulated within the nucleus. Despite remarkable advances in our understanding of genome packaging and gene expression, the interplay among CTs, pairing of parental homologous chromosomes, and genome function during development remains elusive. Here, we employ an Oligopaints-based high-resolution imaging approach to examine variable CT organization in single nuclei during the developmental process of zygotic genome activation. We reveal large-scale chromosome changes with extensive homolog pairing at the whole-chromosome level that decreases locally due to spatial variability in chromosome conformations. In the absence of one homolog copy, the dynamics of CT compaction and RNA polymerase II recruitment are supported by transcriptional changes in haploid embryos. Finally, global inhibition of transcription results in decreased CT opening and no significant impact on CT pairing levels. These findings enhance our understanding of parental genome folding and regulation, which may inform strategies for chromosome-based diseases.

RNA polymerase II↗
PubMed1994

Oedipal sibling triangles.

Sibling triangles exist independent of parent-child triangles and undergo parallel development into constellations bearing significant formal and dynamic similarities to the standard parent-child oedipal relationships. They may exert definitive effects on the individual's identifications, adult object choices, and patterns of relating. Recognition of such constellations and their outcomes is often crucial to successful therapy. A developmental line is delineated with emphasis on the recapitulation throughout development of oedipal sibling issues. Speculations are offered about the possible factors responsible for pathological outcomes of oedipal sibling triangles, and about why, in many cases, oedipal sibling experience may be more influential in development than oedipal parental experience.

Adolescent↗
PubMed2001

Apical accumulation of MARCKS in neural plate cells during neurulation in the chick embryo.

BACKGROUND: The neural tube is formed by morphogenetic movements largely dependent on cytoskeletal dynamics. Actin and many of its associated proteins have been proposed as important mediators of neurulation. For instance, mice deficient in MARCKS, an actin cross-linking membrane-associated protein that is regulated by PKC and other kinases, present severe developmental defects, including failure of cranial neural tube closure. RESULTS: To determine the distribution of MARCKS, and its possible relationships with actin during neurulation, chick embryos were transversely sectioned and double labeled with an anti-MARCKS polyclonal antibody and phalloidin. In the neural plate, MARCKS was found ubiquitously distributed at the periphery of the cells, being conspicuously accumulated in the apical cell region, in close proximity to the apical actin meshwork. This asymmetric distribution was particularly noticeable during the bending process. After the closure of the neural tube, the apically accumulated MARCKS disappeared, and this cell region became analogous to the other peripheral cell zones in its MARCKS content. Actin did not display analogous variations, remaining highly concentrated at the cell subapical territory. The transient apical accumulation of MARCKS was found throughout the neural tube axis. The analysis of another epithelial bending movement, during the formation of the lens vesicle, revealed an identical phenomenon. CONCLUSIONS: MARCKS is transiently accumulated at the apical region of neural plate and lens placode cells during processes of bending. This asymmetric subcellular distribution of MARCKS starts before the onset of neural plate bending. These results suggest possible upstream regulatory actions of MARCKS on some functions of the actin subapical meshwork.

Actins↗
PubMed2000

Identification and characterization of Caenorhabditis elegans gamma-tubulin in dividing cells and differentiated tissues.

gamma-Tubulin is an essential component of the microtubule-nucleation machinery and therefore plays a crucial role during mitosis. To gain further insights into the function of this protein in the events that take place during embryogenesis and differentiation, we carried out detailed studies on gamma-tubulin during all the developmental stages of Caenorhabditis elegans. We identified the gamma-tubulin gene from this organism and analyzed the localization of the protein by both immunofluorescence and GFP reporter construct. We show that gamma-tubulin association with the centrosome is highly dynamic in mitotic cells, being massively recruited at prophase and released at anatelophase. This accumulation in mitotic centrosomes is dramatic during the first embryonic divisions. We provide the first description of the morphological changes at the centrosome level during the orientation of the mitotic spindle and the flattening of the posterior aster. Loss of function of the gamma-tubulin gene by RNAi induces a strong polyploidization of mitotic germ cells and embryos, but does not affect meiosis and pronuclear migration. In addition, we demonstrate the prominent redistribution of gamma-tubulin in adults at basal bodies of amphid and phasmid neurons, and at the apical membrane of polarized intestinal cells.

Amino Acid Sequence↗
PubMed1990

[Parallels in drug utilization--II].

The author analyzes indicators of drug consumption at the regional level in the CSSR and the main towns. The analysis covers the period from 1971-1985 and pertains to the following indicators: A. Expenditure on drugs per day of treatment by functional types of health institutions. B. per capita expenditure on drugs and C. expenditure on drugs. From the indicators dynamic time series are elaborated and the analysis is focused on the development in the past. The author presents basic indices, mean coefficients of growth and parameters characterizing the development in a multiple way. Statistical testing of parallelisms between the obtained developmental parameters reveals factors which influence drug consumption in the investigated territories.

Czechoslovakia↗