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At least 145 records · Page 8Linked to original sources
PubMed1985

Odor-related bulbar EEG spatial pattern analysis during appetitive conditioning in rabbits.

Mildly thirsty rabbits were classically conditioned by reinforcement with water to give a discriminative licking response to the presentation of odors. The jaw movement component of the licking conditioned response (JM CR) was elicited only by the reinforced odor; an increase in the relative frequency of sniffing (RR CR) occurred to both reinforced (CS+) and nonreinforced (CS-) odors. Oscillatory electroencephalographic bursts of high-frequency (40-80 Hz) potentials were recorded epidurally from the lateral olfactory bulb with 64-electrode arrays (8 X 8, 3.5 X 3.5 mm) chronically implanted. Emphasis was on comparing bursts during odor presentation with bursts preceding odor arrival on each trial. A "detection" burst was characterized as occurring immediately after odor arrival and before the sniff response. "Discrimination" bursts occurred during the RR CR and before the JM CR onset. Significant air-odor burst differences (together with sniffing) occurred through up to six sessions for both CS+ and CS- odors for "discrimination" bursts but not for "detection" bursts.

Animals↗
PubMed1988

Two-tiered regulation of spatially patterned engrailed gene expression during Drosophila embryogenesis.

A regulatory cascade, initiated during the syncytial stage of embryogenesis, culminates in the striped pattern of engrailed gene expression at the cellular blastoderm stage. The early regulatory genes, for example the pair-rule genes, are expressed transiently and as their products decay a distinct regulatory programme involving segment polarity genes takes over. This late programme maintains and perhaps modifies the striped pattern of engrailed expression through interactions that may involve cell communication.

Animals↗
PubMed1987

Spatial patterns in electoral wards with high lymphoma incidence in Yorkshire health region.

The possibilities of clustering between those electoral wards which display higher than expected incidences of cases of the lymphomas occurring between 1978 and 1982 are examined. Clusters are defined as being those wards with cases in excess (at a probability of less than 10%) which are geographically adjacent to each other. A separate analysis extends the definition of cluster to include high incidence wards that are adjacent or separated by one other ward. The results indicate that many high incidence lymphoma wards do occur close together and when computer simulations are used to compute expected results, many of the observed results are shown to be highly improbable both in the overall number of clustering wards and in the largest number of wards comprising a 'cluster'.

Computer Simulation↗
PubMed1993

Combinatorial interactions between positive and negative cis-acting elements control spatial patterns of 4CL-1 expression in transgenic tobacco.

The phenylpropanoid enzyme 4-coumarate:coenzyme A ligase (4CL) plays a key role in linking general phenylpropanoid metabolism to end-product specific biosynthetic pathways. During vascular system and floral organ differentiation, the parsley 4CL-1 gene is expressed in a restricted set of tissues and cell types where 4CL activity is required to supply precursors for the synthesis of diverse phenylpropanoid-derived products such as lignin and flavonoids. In order to localize cis-acting elements which specify complex patterns of 4CL-1 expression, we analyzed the expression of internally deleted promoter fragment-GUS fusions in tobacco plants and parsley protoplasts. Elements located between -244 and -78 were required for most aspects of developmentally regulated expression. Within this region, three separate promotor domains containing partially redundant cis-elements directed vascular-specific expression when combined with a TATA-proximal domain. A negative cis-acting element which represses phloem expression was revealed in one of the domains and appears to be responsible for restricting vascular expression to the xylem. Distinct but overlapping promoter domain combinations were required for expression in floral organs, suggesting that different combinations of cis-acting elements may direct expression in different organs. Gel retardation assays were used to demonstrate the formation of DNA-protein complexes between factors present in nuclear extracts of parsley tissue culture cells and various tobacco organs and a 4CL-1 promoter fragment. Competition experiments showed that complex formation required the presence of a 42 bp promoter domain shown to be critical for 4CL-1 expression in vascular and floral tissues. The results are discussed in light of the coordinate expression of 4CL and other phenylpropanoid genes.

Base Sequence↗
PubMed1992

Spatial pattern of cdc2 expression in relation to meristem activity and cell proliferation during plant development.

The p34 protein kinase encoded by the cdc2 gene is a key component of the eukaryotic cell cycle required for the G1- to S-phase transition and entry into mitosis. To study the regulation of plant meristem activity and cell proliferation, we have examined the tissue-specific accumulation of cdc2 transcripts in Arabidopsis thaliana and the related crucifer radish (Raphanus sativus) by in situ hybridization using A. thaliana cdc2 cDNA sequences as a probe. cdc2 transcripts accumulated in leaf primordia and within the vegetative shoot apical meristem. During flower development, high levels of expression were observed in meristems, in the basal regions of developing organs, in the developing vasculature, and associated with rib meristems elaborated late in the development of some floral organs. In root tips, cdc2 transcripts accumulated in the meristematic region and adjacent daughter cells but were not detected in the quiescent center. There was strong hybridization throughout the pericycle, and a further localized accumulation of cdc2 transcripts was observed in the initial stages of the activation of a new meristem at sites of lateral root development. We conclude that cdc2 expression is a critical factor in the regulation of meristem activity and establishment of proliferative competence.

Base Sequence↗
PubMed1992

Spatial pattern of receptor expression in the olfactory epithelium.

A PCR-based strategy for amplifying putative receptors involved in murine olfaction was employed to isolate a member (OR3) of the seven-transmembrane-domain receptor superfamily. During development, the first cells that express OR3 appear adjacent to the wall of the telencephalic vesicle at embryonic day 10. The OR3 receptor is uniquely expressed in a subset of olfactory cells that have a characteristic bilateral symmetry in the adult olfactory epithelium. This receptor and its specific pattern of expression may serve a functional role in odor coding or, alternatively, may play a role in the development of the olfactory system.

Amino Acid Sequence↗
PubMed1994

Experimental specification of cell sorting, tissue spreading, and specific spatial patterning by quantitative differences in cadherin expression.

The sorting-out of embryonic cells from a cell mixture and the selective spreading of one cell population over the surface of another have been attributed to various causes. These include differentials in chemotaxis, in cellular adhesiveness, in cell surface contractility, in speed of cell movement, and in the timing of postulated changes in cellular adhesive and motile properties. One of us earlier predicted on mathematical grounds that two motile cell types differing only in the level of expression of a single cell adhesion system should not only segregate from one another but also arrange themselves with the less cohesive cells enveloping a core of the more cohesive ones. To test these predictions, we combined two populations of L cells transfected with P-cadherin cDNA and expressing this homophilic adhesion molecule in substantially differing amounts. When the two cell populations were intermixed, they segregated to approach a sphere-within-a-sphere configuration, the cell population expressing more P-cadherin forming islands which fused to become an internal "medulla." When the two cell populations were first formed into separate aggregates which were subsequently allowed to fuse, the cell population expressing more P-cadherin was enveloped by its partner, which formed an external "cortex." These observations confirm the early prediction and support the conclusion that both morphogenetic movements and the specific anatomical configurations to which they lead can be determined by particular sets of intercellular adhesive intensities, regardless of how these are generated and in the absence of differentials in other parameters.

Animals↗
PubMed1988

Spatial pattern of myosin phosphorylation in contracting smooth muscle cells: evidence for contractile zones.

We have purified a polyclonal antibody by affinity chromatography which binds specifically to the phosphorylated form of the regulatory light chain (Mr = 20,000) of smooth muscle myosin. This antibody does not stain relaxed, permeabilized smooth muscle cells isolated from guinea pig taenia coli. However, when these cells were stimulated to contract with CaCl2 (100 microM) and ATP (1 mM), the immunofluorescence staining was localized in a series of transverse bands. This distribution of activated myosin appears to reflect an underlying structural organization of the smooth muscle cell cytoskeleton into mechanically coupled contractile zones.

Animals↗
PubMed1969

Spatial patterns of threadlike elements in the axoplasm of the giant nerve fiber of the squid (Loligo pealii L.) as disclosed by differential interference microscopy and by electron microscopy.

The giant nerve fiber of the squid (Loligo pealii L.) has been investigated in situ, and in fresh and fixed preparations, by differential interference microscopy and electron microscopy. A continuous, three-dimensional network, composed of threadlike elements, was disclosed in the axoplasm. The threadlike elements in the axoplasm are twisted as a whole into a steep, right-handed helix. In a peripheral ectoplasmic region, the elements are more parallel to one another and more densely packed than in a central endoplasmic core. The threadlike elements can be resolved into a hierarchy of decreasing order of size. Successive levels of the hierarchy are formed by the association of smaller elements into larger ones. The following levels in the hierarchy of network elements have been distinguished: 1-3-micro-wide threads, 0.1-0.35-micro-wide strands, and 70-250-A-wide unit-filament strands. The differential interference microscope selects, from the network, threads oriented at a specific angle to the long axis of the axon. The specific angle depends upon the orientation of the long axis of the axon relative to the direction of shear. It is postulated that the network configuration is expressed in the solid-state properties of the axoplasm essential for the normal functioning of the nerve fiber.

Animals↗
PubMed1988

Spatial patterns in the fruiting bodies of the cellular slime mold Polysphondylium pallidum.

During morphogenesis in the slime mold Polysphondylium pallidum cell masses are periodically pinched off from the base of the developing sorogen. These masses round up and differentiate into secondary sorogens, which become radially ordered arrays of secondary fruiting bodies called whorls. Here we describe the morphogenesis of P. pallidum and characterize the spacing of whorls along the central stalk of the fruiting body and the spacing of sorocarps within whorls. We find both are highly regular. We propose that the linear spacing of whorls can be accounted for satisfactorily by a model that views the periodic release of cell masses from the base of the developing sorogen as the consequence of an imbalance between forces that orient amoebae toward the tip of the culminating sorogen, and cohesive forces between randomly moving cells in the basal region of the sorogen, which act as a retarding force. The orderly arrangement of fruiting bodies within whorls can be explained most easily by models that employ short-range activation and lateral inhibition.

Cell Differentiation↗
PubMed1991

[Spatial pattern and microvascularization of the ductuli efferentes testis of bulls (Bos taurus)].

The arrangement, origin, course and opening of the ductuli efferents testis of the bull (Bos taurus) were visualized using scanning electron microscopy. The corresponding capillary structure was also described and documented with the help of corrosive microanatomical casts. The number of the ductuli efferents testis of the bull varies narrowly between 12 to 13. Ductuli removed from the surrounding tissue have a length of up to 78 cm. The duct system is composed of linear as well as tortuous parts, permitting division into three distinct segments. Blind ending ductules are very short. We therefore do not see these structures as being associated with spermiostasis. The capillary density as well as the capillary architecture show regional peculiarities. All segments of the ductuli efferents testis are composed of capillaries of the continuous type. The findings indicate that the increased capillary density in the voluminous initial section of the ductuli efferents testis represents the basis for resorptive as well as secretory activities in the bull.

Animals↗
PubMedDate not supplied

Relationship between spatial pattern of basal bodies and membrane skeleton (epiplasm) during the cell cycle of Tetrahymena: cdaA mutant and anti-membrane skeleton immunostaining.

Microtubular basal bodies and epiplasm (membrane skeleton) are the main components of the cortical skeleton of Tetrahymena. The aim of this report was to study functional interactions of basal bodies and epiplasm during the cell cycle. The cortex of Tetrahymena cells was stained with anti-epiplasm antibody. This staining produced a bright epiplasmic layer with a dark pattern of unstained microtubular structures. The fluorescence of the anti-epiplasm antibody disappeared at sites of newly formed microtubular structures, so the new basal body domains and epiplasmic layer could be followed throughout the cell cycle. Different patterns of deployment of new basal bodies were observed in early and advanced dividers. In advanced dividers the fluorescence of the epiplasmic layer diminished locally within the forming fission line where the polymerization of new basal bodies largely extincted. In wild type Tetrahymena, the completion of the micronuclear metaphase/anaphase transition was associated with a transition from the pattern of new basal body deployment and epiplasm staining of the early divider to the pattern of the advanced dividers. The signal for the fission line formation in Tetrahymena (absent in cdaA1 Tetrahymena mutationally arrested in cytokinesis) brings about 1) transition of patterns of deployment of basal bodies and epiplasmic layer on both sides of the fission line; and 2) coordination of cortical divisional morphogenesis with the micronuclear mitotic cycle.

Animals↗