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At least 793 records · Page 44Linked to original sources
PubMed2005

Analysis of calcium-inducible genes in keratinocytes using suppression subtractive hybridization and cDNA microarray.

Terminal differentiation of skin keratinocytes is a vertically directed multistep process that is tightly controlled by the sequential expression of a variety of genes. To gain further insight into the molecular events involved in this process, we used suppression subtraction hybridization (SSH) and cDNA microarray analysis. Messenger RNAs were isolated from primary skin keratinocytes cultured in vitro after treatment with calcium and then SSH was performed. A total of 840 cDNA clones were obtained from subtracted libraries, and these cDNA clones were used to make the microarray slides. Time-course cDNA microarray analysis (1, 3, 7, and 14 days after calcium treatment) revealed the global gene expression profile during keratinocyte differentiation. Of the 840 genes tested, 290 showed a greater than twofold change in expression level at least once over four time points. The genes were clustered into six groups according to their expression pattern using self-organizing map analysis and showed the global feature of function-related regulation. The genes related to keratinocyte differentiation were markedly up-regulated by calcium treatment. In addition, a unique pattern of increase was seen in the expression of genes related to ribosomal proteins. On the other hand, transcripts involved in metabolism, DNA repair, transcription, and translation were generally down-regulated. These results demonstrate the complexity of the gene expression profile that contributes to the spatiotemporal regulation of keratinocyte differentiation.

Calcium↗
PubMed2006

Spatiotemporal expression of duplicate AGAMOUS orthologues during floral development in Phalaenopsis.

The AGAMOUS (AG) family of MADS-box genes plays important roles in controlling the development of the reproductive organs of flowering plants. To understand the molecular mechanisms behind the floral development in the orchid, we isolated and characterized two AG-like genes from Phalaenopsis that we denoted PhalAG1 and PhalAG2. Phylogenetic analysis indicated that PhalAG1 and PhalAG2 fall into different phylogenetic positions in the AG gene family as they belong to the C- and D-lineages, respectively. Reverse transcription-polymerase chair reaction (RT-PCR) analyses showed that PhalAG1 and PhalAG2 transcripts were detected in flower buds but not in vegetative organs. Moreover, in situ hybridization experiments revealed that PhalAG1 and PhalAG2 hybridization signals were observed in the lip, column, and ovule during the floral development of Phalaenopsis, with little difference between the expression patterns of the two genes. These results suggest that both AG-like genes in Phalaenopsis act redundantly with each other in floral development.

Amino Acid Motifs↗
PubMed1995

Genetic analysis of embryonic cis-acting regulatory elements of the Drosophila homeotic gene sex combs reduced.

The homeotic gene Sex combs reduced (Scr) of Drosophila melanogaster is expressed in the labial and prothoracic segments of the ectoderm, in parasegments two and three of the CNS, and in the visceral mesoderm of the anterior and posterior midgut. The mutationally defined function of Scr is to specify the identity of the labial and prothoracic segments and to control the development of the gastric caeca. The Scr locus occupies a chromosomal region of approximately 80 kb within the Antennapedia complex (ANT-C). To understand how Scr's spatiotemporal expression pattern is generated in the embryo, we have mapped its transcriptional regulatory elements using three approaches. First, we examined the expression pattern of Scr in embryos containing chromosomal rearrangements that remove potential Scr regulatory elements. Second, we made and analyzed a set of Scr minigene transformants. Third, we analyzed a set of Scr-lacZ enhancer tester constructs. Using more sensitive anti-SCR antisera, we discovered that Scr is expressed in tissues that were not previously thought to accumulate SCR: a stripe of ectodermal cells in the parasegment 2 region of stage 5 embryos, the embryonic salivary glands, and the dorsal ridge. Four DNA fragments that had previously been shown in an analysis of Scr-lacZ reporter constructs to contain putative Scr enhancer elements were found to have functional enhancers; similarly, another Scr fragment was found to contain a functional repressor. Our results suggest that regulation of Scr in the labial segment and the CNS requires the apparently synergistic action of multiple, widely spaced enhancer elements. Regulation in the prothorax also appears to be controlled by multiple enhancers:one complete pattern element and one subpattern element. In contrast, Scr regulation in the visceral mesoderm is controlled by an enhancer(s) located in only one DNA fragment.

Animals↗
PubMed1994

Event-related desynchronization evoked by auditory stimuli.

Event-Related Desynchronization (ERD) and Synchronization (ERS) of several EEG alpha frequencies was studied in 19 subjects during the presentation of linguistic and/or melodic auditory stimuli. The stimulus length was 1300 msec (+/-100 msec) and the interstimulus interval was 2000 msec. A significant ERD was found during auditory stimulation in the 8-10 Hz and 10-12 Hz alpha frequency bands, and there were also significant differences in the spatiotemporal pattern of the ERD between these frequency bands. Significant ERD was elicited also in the 10-11 and 11-12 Hz frequency bands by auditory stimulation. There were no significant differences between these one-hertz frequency bands. The subjects were assigned to two analysis groups according to their individual alpha peak frequency (10-11 or 11-12 Hz) at rest. The ERD in these groups reached statistical significance and there were significant differences between the groups. The ERD of the two groups differed significantly also when their EEG data was studied in the 10-12 Hz frequency band. The results from this study show that ERD is not modality-specific, i.e., it can be elicited also by auditory stimuli. Moreover, they indicate that it is important to control over interindividual variation in the EEG when studying the ERD phenomenon.

Acoustic Stimulation↗
PubMed2005

Concomitant translocation of Puralpha with its binding proteins (PurBPs) from nuclei to cytoplasm during neuronal development.

Two Puralpha-binding proteins (PurBPs) were found in nuclear extract from mouse brain during P4-P10 by the overlay assay. At P14, they were decreased significantly in nuclear extract and increased in the S3 fraction, indicating their dynamic translocation during development. Western blot analysis also demonstrated concomitant translocation of Puralpha with the PurBPs during P7-P14, when neuronal circuit proceeds. Immunocytochemical study with cultured hippocampal neurons from rat E18 confirmed that nuclear Puralpha was translocated to cytoplasm after plating for 7-14 days. These results suggest that spatiotemporal translocation of Puralpha with the PurBPs from nuclei to cytoplasm has a crucial role in neuronal development.

Age Factors↗
PubMed2004

Additive effects of emotional content and spatial selective attention on electrocortical facilitation.

Affectively arousing visual stimuli have been suggested to automatically attract attentional resources in order to optimize sensory processing. The present study crosses the factors of spatial selective attention and affective content, and examines the relationship between instructed (spatial) and automatic attention to affective stimuli. In addition to response times and error rate, electroencephalographic data from 129 electrodes were recorded during a covert spatial attention task. This task required silent counting of random-dot targets embedded in a 10 Hz flicker of colored pictures presented to both hemifields. Steady-state visual evoked potentials (ssVEPs) were obtained to determine amplitude and phase of electrocortical responses to pictures. An increase of ssVEP amplitude was observed as an additive function of spatial attention and emotional content. Statistical parametric mapping of this effect indicated occipito-temporal and parietal cortex activation contralateral to the attended visual hemifield in ssVEP amplitude modulation. This difference was most pronounced during selection of the left visual hemifield, at right temporal electrodes. In line with this finding, phase information revealed accelerated processing of aversive arousing, compared to affectively neutral pictures. The data suggest that affective stimulus properties modulate the spatiotemporal process along the ventral stream, encompassing amplitude amplification and timing changes of posterior and temporal cortex.

Adult↗
PubMed2003

Gentle dragging of reaction waves.

Using a recently realized "addressable catalyst surface" [Science 294, 134 (2001)]] we study the interaction of chemical reaction waves with prescribed spatiotemporal fields. In particular, we study how a traveling chemical pulse is "dragged" by a localized, moving temperature heterogeneity as a function of its intensity and speed. The acceleration and eventual "detachment" of the wave from the heterogeneity is also explored through simulation and stability analysis.

Journal Article↗
PubMed2000

Neuroglycan C, a neural tissue-specific transmembrane chondroitin sulfate proteoglycan, in retinal neural network formation.

PURPOSE: Neuroglycan C (NGC) is a transmembrane chondroitin sulfate proteoglycan present exclusively in central nervous system tissues. In the current study the expression pattern and characterization of NGC during the development of the retina were investigated. METHODS: Expressional changes of NGC mRNAs during rat retinal development were examined by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). The localization and characterization of NGC core proteins were investigated by immunoblot analysis and immunohistochemistry using an anti-NGC antibody. RESULTS: Immunohistochemical analysis revealed that NGC was highly expressed in the nerve fiber layer (NFL) and inner plexiform layer (IPL) in rat postnatal developing retina. At embryonal stages, NGC immunoreactivities were faint. In contrast, at postnatal developmental stages (approximately postnatal day [P]7), intense immunoreactivity was observed in the NFL and IPL, where active dendrite branching was observed, and conventional synapses began to be formed. As retinal layer differentiation proceeded (from P14 to P42), immunoreactivities in the inner retinal layers gradually became fainter. Immunoblot and semiquantitative RT-PCR analyses showed that the peak level of NGC expression occurred on approximately P7 and P14. Glycosylation of the NGC core protein changed as the retinal layers matured. In immunoelectron microscopic analysis, NGC immunoreactivity was located on the axonal membranes of neuronal cells in the postnatal retina, whereas immunoreactivity was reduced on membranes at the adult stage. In retinal ganglion cells in vitro, NGC was highly localized in their spiny budding neurites. CONCLUSIONS: The results show spatiotemporal expression patterns of NGC, and suggest that it plays a role in the formation of neural networks in retinal development.

Animals↗
PubMed2001

Comparative analysis of the expression patterns of Wnts and Frizzleds during early myogenesis in chick embryos.

During embryogenesis, the transduction of Wnt signals through Frizzled receptors is thought to play integral roles in myogenesis and somite patterning. However, little is known about which Wnt-Frizzled interactions are required for skeletal myogenesis. Thus, we sought to determine which Wnts and Frizzled exhibit expression patterns that are spatiotemporally consistent with the expression of two myogenic determination factors: Myf-5 and MyoD. To accomplish this, we first isolated partial cDNAs for six chick Frizzled orthologues and then compared the expression patterns of chick Frizzleds and Wnts to myogenic and somite patterning factors, such as Myf-5, MyoD, Sonic Hedgehog (Shh), Pax-1 and Pax-3 in Hamburger and Hamilton stage 10 chick. We used these data to generate a schematic composite of expression patterns at the level of the segmental plate and developing somites (stage V) that shows multiple Frizzled and Wnt transcripts expressed in tissues that are overlapping and adjacent to Myf-5 and MyoD expressing tissues.

Animals↗
PubMed2001

Functional dependence and quasiperiodicity in the spatiotemporal dynamics of yttrium iron garnet films.

When thin films of yttrium iron garnet (YIG) are placed in a magnetic field and driven at microwave (rf) frequencies, nonlinear interactions within the material cause the normal microwave spin precession to be modulated at lower frequencies. We measure these lower frequency (kHz) signals at two spatially separated locations on the YIG film and use linear and nonlinear analysis to study the functional dependence of the spin dynamics at one location on the spin dynamics at the other location. We see dynamical states where nonlinear analysis can detect a functional dependence that the linear analysis fails to reveal.

Journal Article↗
PubMed2006

Spatiotemporal pattern of macrophage recruitment after chronic nerve compression injury.

The contribution of macrophages to the pathogenesis of chronic nerve compression (CNC) injuries is presently unclear. We examined the time course and spatial localization of macrophage invasion from 24 hours to 28 days post-CNC injury with immunohistochemistry (IHC) and electron microscopy (EM). To clarify the differences in macrophage activity between different peripheral nerve injuries, we compared CNC injury to a nerve crush (CR) injury at similar time points. Entire counts of macrophages with ED1-immunoreactivity (IR) showed a slow, gradual increase in macrophage number from 24 hours to 28 days post-operatively in compressed sections. ED1-IR was greatest at the site of compression and in distal nerve segments with minimal immunostaining in proximal and normal sections. Quantitative analysis of ED1-IR after crush injury demonstrated a rapid time course of macrophage recruitment with ED1-IR peaking at 48 hours and declining to normal values as early as 21 days post-CR injury. Ultrastructural analysis with EM 14 days post-CNC injury revealed greater macrophage localization in the inner one-third region of normal nerves relative to the outer region. Differences in macrophage localization within inner and outer regions of compressed sections were negligible, as macrophages were found diffusely throughout the endoneurium by day 14. Our findings suggest that macrophage recruitment is dependent upon proximity to neural vasculature with relative macrophage density highest specifically around endoneurial blood vessels in both normal and compressed sections. Taken together, our results detail the unique spatiotemporal dynamics of macrophage recruitment early after CNC injury as distinct from a crush injury.

Animals↗
PubMed2004

Analysis for space-time clustering of CJD cases, Kentucky, 1988-1997.

Creutzfeldt-Jakob Disease (CJD) is a transmissible spongiform encephalopathy of humans. It can be transmitted iatrogenically or inherited as an autosomal dominant trait. However, most cases (85%) of the disease are sporadic, occurring stochastically in approximately one person per million population. In 1996, a new, neuropathologically distinct variant of CJD was recognized in a group of unusually young patients who had apparently been infected by exposure to the agent of bovine spongiform encephalopathy (BSE) via contaminated beef products. This prompted many countries, including the United States, to renew their surveillance for CJD to assess the possibility of other variant cases. Spatiotemporal aggregation of cases may indicate a common source of infection or some other shared risk factor. In order to assess the possibility of variant cases, death certificate data was used to examine the spatiotemporal patterns of CJD mortality in Kentucky over a ten-year period. Space-by-time clustering was assessed using Cluster 3.1 software. The findings of this study produced some evidence for a cluster of six cases in central Kentucky. Overall, however, there was little or no evidence to suggest the occurrence of variant or unconventionally acquired cases.

Age Distribution↗
PubMed2005

Spatiotemporal distribution of insects and mites in horizontally stored wheat.

Samples were taken from a flat storage facility located in central Greece, filled with approximately 45 tons of hard wheat, to assess the spatiotemporal distribution of stored-product insects and mites. The wheat was stored in a 1.5-m-deep bulk from June 2001 until March 2002. The samples were taken with a partitioned grain trier during the entire storage period, at 10-d intervals. The trier samples were examined separately for the upper, medial, and lower 0.5 m of the bulk. The spatial distribution of the insect and mite species found was examined by contour analysis based on the numbers of individuals in the trier samples. Nine insect and 20 mite taxa were found during the sampling period. The most abundant insect species were Tribolium castaneum (Herbst), Cryptolestes ferrugineus (Stephens), and Rhyzopertha dominica (F.); the most abundant mite species were Lepidoglyphus destructor (Schrank), Acarus siro L., and the predator Cheyletus malaccensis Oudemans. The highest population densities for the majority of the insect and mite species were recorded during autumn. The majority of the individuals of the most abundant insect and mite species were found in the upper 0.5 m of the bulk, with the exception of C. malaccensis, which was equally distributed in the upper and medial 0.5 m of the bulk. The spatiotemporal distribution during the entire experimental period was notably varied according to the insect and mite species.

Animals↗
PubMed2002

Repeatability of back kinematics in horses during treadmill locomotion.

We tested the hypothesis that repeatability of a standardised protocol for quantifying back kinematics is sufficiently high not to prevent its use in the clinical evaluation of horses with back problems. We investigated the extent to which differences between laboratories may affect the results when a standardised protocol is used. As a clinical tool, movement analysis techniques are helpful for the objective and quantitative assessment of kinematics. Knowledge about the repeatability of the kinematic data is very important. The present study investigates the repeatability of back kinematics in 10 sound horses over 5 successive days and in 2 laboratories (5 horses at each location). Measurements were performed on the treadmill during the walk and the trot. The between-stride, between-day and between-horse repeatability were determined. A high degree of between-stride and between-day repeatability was observed in the spatiotemporal parameters and in the time-angle diagrams of thoracic and lumbar vertebrae, the sacrum and the hindlimb during both the walk and trot. Much more variability was found between horses, with the highest degree of dissimilarity in the lateral bending rotation of the L1 vertebra. For range of motion values, the between-day coefficient of variability was <14% and the between-horse coefficient of variability was up to 4 times higher. Small differences were found in range of motion values between the 2 laboratories. It is concluded that an analysis of back kinematics in the horse can provide highly repeatable data, warranting clinical use.

Animals↗
PubMed2006

Synchronization and propagation of bursts in networks of coupled map neurons.

The present paper studies regular and complex spatiotemporal behaviors in networks of coupled map-based bursting oscillators. In-phase and antiphase synchronization of bursts are studied, explaining their underlying mechanisms in order to determine how network parameters separate them. Conditions for emergent bursting in the coupled system are derived from our analysis. In the region of emergence, patterns of chaotic transitions between synchronization and propagation of bursts are found. We show that they consist of transient standing and rotating waves induced by symmetry-breaking bifurcations, and can be viewed as a manifestation of the phenomenon of chaotic itinerancy.

Action Potentials↗
PubMed1999

Spatiotemporal activity patterns of rat cortical neurons predict responses in a conditioned task.

Precise and repeated spike-train timings within and across neurons define spatiotemporal patterns of activity. Although the existence of these patterns in the brain is well established in several species, there has been no direct evidence of their influence on behavioral output. To address this question, up to 15 neurons were recorded simultaneously in the auditory cortex of freely moving rats while animals waited for acoustic cues in a Go/NoGo task. A total of 235 significant patterns were detected during this interval from an analysis of 13 hr of recording involving over 1 million spikes. Of particular interest were 129 (55%) patterns that were significantly associated with the type of response the animal made later, independent of whether the response was that prompted by the cue because the response occurred later and the cue was chosen randomly. Of these behavior-predicting patterns, half (59/129) were associated with an enhanced tendency to go in response to the stimulus, and for 11 patterns of this subset, trials including the pattern were followed by significantly faster reaction time than those lacking the pattern. The remaining behavior-predicting patterns were associated with an enhanced NoGo tendency. Overall mean discharge rates did not vary across trials. Hence, these data demonstrate that particular spatiotemporal patterns predict future behavioral responses. Such presignal activity could form templates for extracting specific sensory information, motor programs prespecifying preference for a particular act, and/or some intermediate, associative brain process.

Acoustic Stimulation↗
PubMedDate not supplied

Spatiotemporal dynamics of epidemics: synchrony in metapopulation models.

Multi-patch models - also known as metapopulation models - provide a simple framework within which the role of spatial processes in disease transmission can be examined. An n-patch model which distinguishes between k different classes of individuals is considered. The linear stability of spatially homogeneous solutions of such models is studied using an extension of an analysis technique previously described for a population setting in which individuals migrate between patches according to a simple linear term. The technique considerably simplifies the analysis as it decouples the nk dimensional linearized system into n distinct k-dimensional systems. An important feature of the spatial epidemiological model is that the spatial coupling may involve non-linear terms. As an example of the use of this technique, the dynamical behavior in the vicinity of the endemic equilibrium of a symmetric SIR model is decomposed into spatial modes. For parameter values appropriate for childhood diseases, expressions for the eigenvalues corresponding to in-phase and out-of-phase modes are obtained, and it is shown that the dominant mode of the system is an in-phase mode. Furthermore, the out-of-phase modes are shown to decay much more rapidly than the in-phase mode for a broad range of coupling strengths.

Communicable Diseases↗
PubMed1994

Spatiotemporal pattern of expression of tenascin-like molecules in a developing insect olfactory system.

During the development of the olfactory (antennal) lobe of the moth Manduca sexta, olfactory sensory axons induce glomerular branching patterns in their target neurons. Glial cells, by surrounding the developing glomerular template, are thought to mediate the developmental influence of olfactory axons on these branching patterns. Previous studies have demonstrated that, in the absence of glia, neurons in the antennal lobe branch in an aglomerular fashion, even in the presence of competent antennal axons (Oland and Tolbert, 1988, J. Comp. Neurol. 278:377-387; Oland et al., 1988, J. Neurosci. 8:353-367). We have begun to explore the molecular basis by which glial cells could influence patterns of neurite branching. For this work, we have utilized immunocytochemical techniques and a partial biochemical analysis to demonstrate that molecules antigenically similar and comparable in size to mammalian tenascin are localized on the neuropil-associated glial cells that form borders around glomeruli in the developing antennal lobe. These tenascin-like molecules associated with neuropilar glia are present at critical stages of glomerulus development; tenascin-like immunoreactivity declines after glomeruli form and become stabilized. Neither the arrival nor the absence of antennal axons in the lobe induces changes in either the molecular forms or the amounts of tenascin-like molecules. The spatiotemporal pattern of expression of tenascin-like molecules suggests that they are in a position to participate in the formation of a glomerular neuropil and could form a molecular barrier that constrains neurite outgrowth strictly to glomeruli.

Animals↗