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PubMed1991

Expression of two members of the Wnt family during mouse development--restricted temporal and spatial patterns in the developing neural tube.

The Wnt gene family encodes a group of cysteine-rich proteins implicated in intercellular signaling during several stages of vertebrate development. This family includes Wnt-1 and Wnt-3, both discovered as activated oncogenes in mouse mammary tumors. Here we describe the molecular cloning of an additional member of the Wnt family, called Wnt-3A, and the spatial and temporal expression pattern of this gene as well as that of its close relative Wnt-3. The putative amino acid sequences of both proteins are almost 90% identical, but in situ hybridization to mouse embryo sections showed highly restricted patterns of expression of Wnt-3 and Wnt-3A, largely in separate areas in the developing nervous system. In the spinal cord Wnt-3 was expressed at low levels in the alar laminae and in the ventral horns, whereas Wnt-3A expression was confined to the roof plate. In the developing brain Wnt-3 was expressed broadly across the dorsal portion of the neural tube with a rostral boundary of expression at the diencephalon. In contrast, Wnt-3A was expressed in a narrow region very close to the midline; expression extended into the bifurcating telencephalon, in a highly localized fashion. Both Wnt-3 and Wnt-3A were expressed in the ectoderm, and Wnt-3A was also expressed in the periumbilical mesenchyme. Characteristic expression patterns of these two closely related genes suggest that Wnt-3 and Wnt-3A play distinct roles in cell-cell signaling during morphogenesis of the developing neural tube.

Amino Acid Sequence↗
PubMed1991

Temporal and spatial patterns of transin/stromelysin RNA expression following toxic injury in rat liver.

We have examined the expression of the extracellular matrix-degrading metalloprotease transin/stromelysin during the early phases of rat liver regeneration following toxic injury by a single dose of carbon tetrachloride (CCl4). In situ hybridization displayed cell type-specific spatial and temporal RNA expression patterns with high transcript levels in small proportions of hepatocytes and non-parenchymal cells, peaking at 24 and 48 h after intoxication, respectively. In agreement with the presence of c-fos and c-jun recognition sites on the transin gene, expression of these oncogenes preceded transin expression. Transin-expressing hepatocytes were largely localized in areas subsequently eliminated by necrosis due to CCl4 intoxication. As a consequence of these expression patterns and the key function of transin as an activator of interstitial collagenase, it seems that the hepatic fibrosis observed after CCl4 administration may be related to fibrogenesis unbalanced by fibrolysis due to altered transin expression.

Animals↗
PubMed1990

Regulatory elements from the related spec genes of Strongylocentrotus purpuratus yield different spatial patterns with a lacZ reporter gene.

The Spec1 and Spec2 genes of Strongylocentrotus purpuratus are closely associated with the differentiation of aboral ectoderm. To examine cis-regulatory elements involved in the spatial expression of the Spec genes, we fused the Escherichia coli lacZ gene containing a nuclear targeting signal to 5'flanking DNA plus 5' untranslated leader sequences from Spec1, Spec2a, and Spec2c. All three genes contain 700 bp of highly conserved DNA in their upstream regions, but in Spec1 and Spec2c large insertions interrupt the conserved regions. The Spec-lacZ reporter gene plasmids were microinjected into eggs of S. purpuratus, Lytechinus variegatus, and L. pictus, and beta-galactosidase activity was determined in situ by X-gal staining. The Spec2a-lacZ fusion gene, which contained 1516 bp of 5' flanking DNA and 18 bp of 5' untranslated leader sequence, was preferentially expressed in aboral ectoderm cells in all three species. The Spec1-lacZ fusion gene was expressed in a strikingly different fashion--preferentially in primary and secondary mesenchyme cells, occasionally in aboral ectoderm cells, and less often in oral ectoderm and endoderm cells. The staining pattern was the same in either homologous or heterologous embryos. The Spec2c-lacZ fusion gene, like Spec2a-lacZ, was preferentially expressed in aboral ectoderm, but staining of other cell types was frequently observed. To further delineate sequences required for correct spatial expression, we deleted 800 bp of 5' flanking DNA from the Spec2a-lacZ fusion gene, resulting in a delta Spec2a-lacZ fusion gene that contained only the conserved DNA region. This gene fusion showed preferential expression in aboral ectoderm cells. However, the cell type specificity was not as great as with the parental Spec2a-lacZ plasmid. These experiments implied that the conserved DNA region, associated with all Spec genes examined, was insufficient for complete aboral ectoderm specificity, and suggested that a spatial repressor element existed between -1516 and -697 bp in the 5' flanking DNA of Spec2a.

Animals↗
PubMed1991

Temporal and spatial patterns of transgene expression in aging adult mice provide insights about the origins, organization, and differentiation of the intestinal epithelium.

We have used liver fatty acid-binding protein/human growth hormone (L-FABP/hGH) fusion genes to explore the temporal and spatial differentiation of intestinal epithelial cells in 1- to 12-month-old transgenic mice. The intact, endogenous L-FABP gene (Fabpl) was not expressed in the colon at any time. Young adult transgenic mice containing nucleotides -596 to +21 of the rat L-FABP gene linked to the hGH gene (minus its 5' nontranscribed domain) demonstrated inappropriate expression of hGH in enterocytes and many enteroendocrine cells of most proximal and mid-colonic crypts (glands). Rare patches of hGH-negative crypts were present. With increasing age, a wave of "extinction" of L-FABP (-596 to +21)/hGH expression occurred, first in the distal colon and then in successively more proximal regions, leaving by 10 months of age only rare hGH-positive multicrypt patches. At no time during this progressive silencing of transgene expression were crypts observed that contained a mixture of hGH-positive and -negative cells at a particular cell stratum. Young (5-7 weeks) mice containing a L-FABP (-4000 to +21)/hGH transgene also demonstrated inappropriate expression of the transgene in most proximal colonic crypts. However, the additional 3.3 kilobases of upstream sequence resulted in much more rapid extinction of reporter expression, leaving by 5 months of age only scattered single crypts with detectable levels of hGH. This age-related extinction of L-FABP/hGH expression did not involve enterocytes and enteroendocrine cells in the (proximal) small intestine. These results indicate that cis-acting elements outside of nucleotides -4000 to +21 are necessary to fully modulate suppression of colonic L-FABP expression. They also define fundamental changes in colonic epithelial cell populations during adult life. Our data suggest that (i) a single stem cell gives rise to all cells that populate a given colonic crypt, (ii) stem cells represented in several adjacent crypts may be derived from a common progenitor, and (iii) such a progenitor cell may repopulate colonic crypts with stem cells during adult life. Since each colonic crypt contains the amplified descendants of its stem cell, transgenes may be powerful tools for characterizing the spatial and biological features of gut stem cells and their progenitors during life.

Aging↗
PubMed1990

Spatial patterns of attendance at general practitioner services.

Geographical theory suggests that consumers will travel to the centre nearest to their residence which offers a particular service. This is a weak indicator of surgery attendance patterns in Gisborne, New Zealand. Nearby surgeries were attended, rather than the nearest available. Various attributes of the practices and the patients were examined to discover their influence on attendance patterns. The distribution of the practices themselves had a significant effect upon relative surgery attendance. Prior knowledge of services was particularly important in determining surgery selection and continued attendance. This accounted for the spatially unconstrained attendance of many Maori. Greater personal mobility enabled higher income households to travel further to attend. Conversely, the less mobile were spatially bounded.

Catchment Area, Health↗
PubMed1990

Double dissociation between temporal and spatial pattern processing in patients with frontal and parietal damage.

One hundred and twenty nine patients affected by a cerebral lesion confined to a single lobe, underwent a battery of tests including the "Temporal Rule Induction" (TRI) and the Raven's "Coloured Progressive Matrices" (CPM). Frontal patients scored lower than any other group on TRI and parietal patients on CPM. This contrasting pattern of performance provides strong empirical support to the hypothesis that the frontal lobe is specifically involved in tasks that require a control on temporally ordered information whereas the parietal lobe is concerned with cognitive activities that imply visuo-spatial analysis.

Adult↗
PubMed1992

Development of the spatial pattern of retinoic acid receptor-beta transcripts in embryonic chick facial primordia.

Retinoic acid causes a range of embryonic defects, including craniofacial abnormalities, in both birds and mammals and is believed to have a number of roles in normal development. We have previously shown that the distribution of retinoic acid receptor-beta (RAR-beta) transcripts is spatially restricted within the neural-crest-derived upper beak primordia of the chick embryo. We have now used in situ hybridisation to trace the distribution of RAR-beta transcripts during the migration of cranial neural crest cells and during formation of these primordia. RAR-beta transcripts were present in a subset of migrating neural-crest-derived cells in the head of the stage 10 embryo. These cells were situated in pathways followed by cells that migrate from the neural crest overlying the posterior prosencephalic/anterior mesencephalic region of the developing brain. Cells containing RAR-beta transcripts accumulated around the developing eyes and in the regions of the ventral head from which the upper beak primordia later develop. We mapped the distribution of RAR-beta transcripts as the facial primordia were forming, with particular reference to the development of the maxillary primordia. We found that these form in a region of the ventral head that includes the boundary between regions of high and low levels of RAR-beta transcripts. The boundary between these two groups of cells persisted as the maxillary primordia developed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Cell lineages, developmental timing, and spatial pattern formation in embryos of free-living soil nematodes.

From soils of various origins we have isolated a number of nematode strains and cultured them on agar plates. We have analyzed their anatomy, reproduction, and particularly their pattern of embryogenesis. With respect to early cleavage we can define six different classes. The basic scheme of embryogenesis is similar in all strains but considerable differences were observed in detail. Embryogenesis is more than five times longer in the slowest strain than in the fastest. The following general correlation was found: The slower embryogenesis proceeds in a strain, the relatively earlier the cleavage of germline cells occurs. In the fastest strain the primordial germ cell P4 is present at the 24-cell stage, while in the slowest strain it is already generated in the 5-cell stage. We hypothesize that germline cleavages have to occur within a certain time limit to preserve germline quality. The typical reversal of cleavage polarity in the division of the germline cell P2 is absent in the slowest, on other grounds apparently more primitive strain. This results in an unusual spatial arrangement of cells transiently. However, prior to gastrulation as a consequence of compensatory cell migrations (which may indicate the necessity for cell interactions), the pattern becomes very similar to that in the other strains. We propose that a standard cellular configuration is required at the beginning of gastrulation to ensure normal further development. Early cell interactions might be necessary to achieve this standard pattern. In about half of the analyzed strains cellular structures can be marked with an antibody raised against germline-specific granules of Caenorhabditis elegans. Our results do not support the notion that the staining pattern for P granules is a useful indicator for phylogenetic relationship.

Animals↗
PubMed1990

Developmental regulation and spatial pattern of expression of the structural genes for nitrogenase in the cyanobacterium Anabaena.

Depriving the cyanobacterium Anabaena of fixed nitrogen induces the differentiation of heterocysts at intervals along its filaments. To test whether the oxygen-deficient conditions believed to prevail within mature heterocysts are sufficient, in the absence of fixed nitrogen, to elicit the expression of nitrogenase, PnifHDK was fused transcriptionally to luxAB (encoding luciferase). Expression, monitored from individual cells as light emission, was localized (with a resolution of approximately 1 micron) to differentiated cells, whether or not oxygen was present. Anabaena PCC 7118 is a heterocystless mutant strain that is known to fix nitrogen when deprived of combined nitrogen under anaerobic conditions. Three lines of evidence indicate that the mutant has retained the ability to develop a pattern despite its inability to make heterocysts. First, morphologically distinct cells appear at nonrandom intervals when filaments are starved of nitrogen. Second, these cells, like heterocysts, have little or no phycocyanin-dependent fluorescence. Third, nitrogen-starved filaments fragment, with fragment lengths similar to the spacing normally seen between heterocysts. Expression of PnifHDK-luxAB was largely confined to differentiated cells in the mutant as in the wild-type strain. These results provide evidence for a causal relationship between development and transcriptional events in Anabaena.

Aerobiosis↗
PubMed1979

Spatial patterns for an interaction-diffusion equation in morphogenesis.

A certain interaction-diffusion equation occurring in morphogenesis is considered. This equation is proposed by Gierer and Meinhardt, which is introduced by Child's gradient theory and Turing's idea about diffusion driven instability. It is shown that slightly asymmetric gradients in the tissue produce stable striking patterns depending on its asymmetry, starting from uniform distribution of morphogens. The tool is the perturbed bifurcation theory. Moreover, from a mathematical point of view, the global existence of steady state solutions with respect to some parameters is discussed.

Cell Differentiation↗
PubMed1990

Temporal and spatial patterns of transforming growth factor-beta 1 expression in developing rat molars.

Regulatory peptides of the TGF-beta family affect various aspects of embryonic development. Recent immunolocalization and in situ hybridization studies have demonstrated a specific time- and tissue-dependent expression of TGF-beta 1 in the developing mouse embryo. The purpose of this study was to evaluate the distribution of TGF-beta 1 within rat molars at different stages of development, using a well-characterized antibody, highly specific for TGF-beta 1, and immunohistochemical methods of detection. TGF-beta 1 was immunolocalized intensely within the ectodermally derived stellate reticulum and the mesenchyme of the dental papilla at the bell stage of development. Marked immunostaining was also evident in the papillary layer and the reduced dental organ subjacent to ameloblasts in the differentiation and secretory phases of amelogenesis. During the formation of coronal tissues and in the pre-eruptive phase, immunoreactive TGF-beta 1 was localized conspicuously within the dental follicle overlying the tooth germ. This temporospatial pattern of expression of TGF-beta 1 appears to correlate with specific events in morphogenesis, histogenesis and cytodifferentiation during tooth development.

Ameloblasts↗
PubMed1991

Changes in temporal and spatial patterns of Gi protein expression in postimplantation mouse embryos.

We previously demonstrated the presence of GTP-binding proteins, G proteins, in the preimplantation mouse embryo (Jones and Schultz, 1990. Dev. Biol. 139, 250-262). These studies have been extended to the Day 6.5, 7.5, and 8.5 gestation embryo by employing PT-catalyzed ADP-ribosylation and immunoblotting techniques. We report here that the amount of embryonic alpha i increases from Day 6.5 to Day 7.5 of gestation, and remains at about the same level at Day 8.5. In contrast, the extent of PT-catalyzed ADP-ribosylation of Gi alpha protein(s) decreases between Days 6.5 and 7.5--this decrease is global and not restricted to a particular germ layer of the Day 7.5 embryo--and then dramatically increases by Day 8.5 of gestation. In the Day 8.5 gestation embryo, the extent of PT-catalyzed ADP-ribosylation of Gi alpha proteins increases along the anterior-posterior axis, whereas the amount of immunoreactive alpha i subunit decreases along this axis. By using a combination of PT-catalyzed ADP-ribosylation and immunoprecipitation with antisera specific for alpha i1, alpha i2, or alpha i3, we report that all three alpha i subtypes are present in the Day 8.5 gestation mouse embryo. Results of these experiments suggest that an activation of Gi proteins occurs between Days 6.5 and 7.5 of gestation in the postimplantation embryo, a time during which the embryo is gastrulating, and that a decreasing gradient of activation exists along the anterior to posterior axis in the Day 8.5 gestation embryo. Last, we report that oocytes, eggs, and preimplantation embryos possess all three subtypes of alpha i.

Amino Acid Sequence↗
PubMed1977

Temporo-spatial pattern of subcortical spike activity in kindling epilepsy. A statistical approach.

Recording electrodes were implanted stereotaxically in limbic and thalamic structures and the mesencephalic reticular formation in twelve cats. The animals were submitted to daily stimulation of the left amygdaloid nucleus following the technique for the kindling procedure, always combined with 5 h 30 min post-stimulation monitoring. After about 18 days, generalized convulsive activity was established. The following results concerning the quantitative evolution of spontaneously occurring interictal spikes were obtained. Amygdaloid nuclei, the hippocampus and the thalamic nucleus ventralis lateralis (VL) demonstrated an increase of discharge activity during the kindling procedure, following by a significant decrease after convulsions had been elicited. Thalamic nucleus centrum medianum (CM) was the only recording site investigated where the amount of interictal discharge increased and remained at a high level even after generalized convulsions had been established. Fourier analysis of slow oscillations in discharge generation yielded two main types of significant periodicity. A 165 min oscillation could be detected in all structures tested except reticular formation, which developed a 110 min cycle shared only with the thalamic CM. Significant correlations in spike activity were obtained from various structures. Stimulated amygdala seemed to have alternating relations with thalamic CM and VL, whereas stimultaneous oscillations excisted between MRF and CM. The occurrence of high voltage spikes in both contralateral and ipsilateral amygdalae was shown to be significantly correlated.

Action Potentials↗