Immunohistochemical localization of fibromodulin in the periodontium during cementogenesis and root formation in the rat molar

Background: Cementum is essential for periodontal regeneration, as it provides anchorage between the root surface and the periodontal ligament. A variety of macromolecules present in the extracellular matrix of the periodontium, including proteoglycans, are likely to play a regulatory role in cementogenesis. Recently, the small leucine-rich proteoglycan, fibromodulin, has been isolated from bovine periodontal ligament and localized in bovine cementum, as well as in human periodontal ligament. Objective: The aim of this study was to examine the distribution of fibromodulin during cementogenesis and root formation. Methods: A standard indirect immunoperoxidase technique was employed, using an antifibromodulin polyclonal antibody on sections of molar teeth from rats aged 3, 5 and 8 weeks. Results: Immunoreactivity to fibromodulin was evident in the periodontal ligament in all sections. An intense positive stain was observed in the extracellular matrix where the periodontal ligament fibers insert into the alveolar bone and where the Sharpey's fibers insert into the cementum. There was no staining evident in the mineralized cellular and acellular cementum. The intensity of immunoreactivity to the antifibromodulin antibody increased proportionally with increasing tissue maturation. Conclusion: The results from this study suggest that fibromodulin is a significant component of the extracellular matrix in the periodontal ligament during development, and may play a regulatory role in the mineralization process or maintaining homeostasis at the hard-soft tissue interface during cementogenesis.

Conspicuous males suffer higher predation risk: visual modelling and experimental evidence from lizards

Colour pattern variation is a striking and widespread phenomenon. Differential predation risk between individuals is often invoked to explain colour variation, but empirical support for this hypothesis is equivocal. We investigated differential conspicuousness and predation risk in two species of Australian rock dragons, Ctenophorus decresii and C. vadnappa. To humans, the coloration of males of these species varies between 'bright' and 'dull'. Visual modelling based on objective colour measurements and the spectral sensitivities of avian visual pigments showed that dragon colour variants are differentially conspicuous to the visual system of avian predators when viewed against the natural background. We conducted field experiments to test for differential predation risk, using plaster models of 'bright' and 'dull' males. 'Bright' models were attacked significantly more often than 'dull' models suggesting that differential conspicuousness translates to differential predation risk in the wild. We also examined the influence of natural geographical range on predation risk. Results from 22 localities suggest that predation rates vary according to whether predators are familiar with the prey species. This study is among the first to demonstrate both differential conspicuousness and differential predation risk in the wild using an experimental protocol. (C) 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.

Localization of a novel melanoma susceptibility locus to 1p22

Over the past 20 years, the incidence of cutaneous malignant melanoma (CMM) has increased dramatically worldwide. A positive family history of the disease is among the most established risk factors for CMM; it is estimated that 10% of CMM cases result from an inherited predisposition. Although mutations in two genes, CDKN2A and CDK4, have been shown to confer an increased risk of CMM, they account for only 20%-25% of families with multiple cases of CMM. Therefore, to localize additional loci involved in melanoma susceptibility, we have performed a genomewide scan for linkage in 49 Australian pedigrees containing at least three CMM cases, in which CDKN2A and CDK4 involvement has been excluded. The highest two-point parametric LOD score (1.82; recombination fraction [theta] 0.2) was obtained at D1S2726, which maps to the short arm of chromosome 1 (1p22). A parametric LOD score of 4.65 (theta = 0) and a nonparametric LOD score of 4.19 were found at D1S2779 in nine families selected for early age at onset. Additional typing yielded seven adjacent markers with LOD scores 13 in this subset, with the highest parametric LOD score, 4.95 (theta = 0) ( nonparametric LOD score 5.37), at D1S2776. Analysis of 33 additional multiplex families with CMM from several continents provided further evidence for linkage to the 1p22 region, again strongest in families with the earliest mean age at diagnosis. A nonparametric ordered sequential analysis was used, based on the average age at diagnosis in each family. The highest LOD score, 6.43, was obtained at D1S2779 and occurred when the 15 families with the earliest ages at onset were included. These data provide significant evidence of a novel susceptibility gene for CMM located within chromosome band 1p22.

Localization of the Epstein-Barr virus protein LMP 1 to exosomes

The Epstein-Barr virus latent membrane protein (LMP 1) functions as a constitutively active signalling molecule and associates in lipid rafts clustered with other signalling molecules. Using immunofluorescent confocal microscopy, LMP 1 was shown to have an heterogeneous distribution among individual cells which was not related to the cell cycle stage. LMP 1 was shown to localize to intracellular compartments in cells other than the plasma membrane, Co-labelling of cells with both an LIMP 1 antibody and an antibody to the Golgi protein GS15 revealed that the intracellular LMP 1 partly co-localized with the Golgi apparatus. Further confirmation of intracellular LMP 1 localization was obtained by immunoelectron microscopy with rabbit polyclonal LIMP 1 antibodies and cryosectioning. As well as being present in intracellular foci, LMP 1 co-localized in part with MHC-II and was present on exosomes derived from a lymphoblastoid cell line. Preparations of LMP 1 containing exosomes were shown to inhibit the proliferation of peripheral blood mononuclear cells, suggesting that LIMP 1 could be involved in immune regulation. This may be of particular relevance in EBV-associated tumours such as nasopharyngeal carcinoma and Hodgkin's disease, as LMP 1-containing exosomes may be taken up by infiltrating T-lymphocytes, where LMP 1 could exert an anti-proliferative effect, allowing the tumour cells to evade the immune system.

Visual Biology of Hawaiian Coral Reef Fishes. III. Environmental Light and an Integrated Approach to the Ecology of Reef Fish Vision

In the previous two papers in this three-part series, we have examined visual pigments, ocular media transmission, and colors of the coral reef fish of Hawaii. This paper first details aspects of the light field and background colors at the microhabitat level on Hawaiian reefs and does so from the perspective and scale of fish living on the reef. Second, information from all three papers is combined in an attempt to examine trends in the visual ecology of reef inhabitants. Our goal is to begin to see fish the way they appear to other fish. Observations resulting from the combination of results in all three papers include the following. Yellow and blue colors on their own are strikingly well matched to backgrounds on the reef such as coral and bodies of horizontally viewed water. These colors, therefore, depending on context, may be important in camouflage as well as conspicuousness. The spectral characteristics of fish colors are correlated to the known spectral sensitivities in reef fish single cones and are tuned for maximum signal reliability when viewed against known backgrounds. The optimal positions of spectral sensitivity in a modeled dichromatic visual system are generally close to the sensitivities known for reef fish. Models also predict that both UV-sensitive and red-sensitive cone types are advantageous for a variety of tasks. UV-sensitive cones are known in some reef fish, red-sensitive cones have yet to be found. Labroid colors, which appear green or blue to us, may he matched to the far-red component of chlorophyll reflectance for camouflage. Red cave/hole dwelling reef fish are relatively poorly matched to the background they are often viewed against but this may be visually irrelevant. The model predicts that the task of distinguishing green algae from coral is optimized with a relatively long wavelength visual pigment pair. Herbivorous grazers whose visual pigments are known possess the longest sensitivities so far found. Labroid complex colors are highly contrasting complementary colors close up but combine, because of the spatial addition, which results from low visual resolution, at distance, to match background water colors remarkably well. Therefore, they are effective for simultaneous communication and camouflage.

Visual Biology of Hawaiian Coral Reef Fishes. I. Ocular Transmission and Visual Pigments

The visual biology of Hawaiian reef fishes was explored by examining their eyes for spectral sensitivity of their visual pigments and for transmission of light through the ocular media to the retina. The spectral absorption curves for the visual pigments of 38 species of Hawaiian fish were recorded using microspectrophotometry. The peak absorption wavelength (lambda(max)) of the rods varied from 477-502 nm and the lambda(max) of individual species conformed closely to values for the same species previously reported using a whole retina extraction procedure. The visual pigments of single cone photoreceptors were categorized, dependent on their lambda(max)-values, as ultraviolet (347-376 nm), violet (398-431 nm) or blue (439-498 nm) sensitive cones. Eight species possessed ultraviolet-sensitive cones and 14 species violet-sensitive cones. Thus, 47% of the species examined displayed photosensitivity to the short-wavelength region of the spectrum. Both identical and nonidentical paired and double cones were found with blue sensitivity or green absorption peaks (> 500 nm). Spectrophotometry of the lens, cornea, and humors for 195 species from 49 families found that the spectral composition of the light transmitted to the retina was most often limited by the lens (73% of species examined). Except for two unusual species with humor-limited eyes, Acanthocybium solandri (Scombridae) and the priacanthid fish, Heteropriacanthus cruentatus, the remainder had corneal-limited eyes. The wavelength at which 50% of the light was blocked (T50) was classified according to a system modified from Douglas and McGuigan (1989) as Type I, T50 < = 355 nm, (32 species); Type IIa, 355 < T50 < = 380 nm (30 species); Type IIb, 380 < T50 405 nm (84 species). Possession of UV-transmitting ocular media follows both taxonomic and functional lines and, if the ecology of the species is considered, is correlated with the short-wavelength visual pigments found in the species. Three types of short-wavelength vision in fishes are hypothesized: UV-sensitive, UV-specialized, and violet-specialized. UV-sensitive eyes lack UV blockers (Type I and IIa) and can sense UV light with the secondary absorption peak or beta peak of their longer wavelength visual pigments but do not possess specialized UV receptor cells and, therefore, probably lack UV hue discrimination. UV-specialized eyes allow transmission of UV light to the retina (Type I and IIa) and also possess UV-sensitive cone receptors with peak absorption between 300 and 400 nm. Given the appropriate perceptual mechanisms, these species could possess true UV-color vision and hue discrimination. Violet-specialized eyes extend into Type IIb eyes and possess violet-sensitive cone cells. UV-sensitive eyes are found throughout the fishes from at least two species of sharks to modern bony fishes. Eyes with specialized short-wavelength sensitivity are common in tropical reef fishes and must be taken into consideration when performing research involving the visual perception systems of these fishes. Because most glass and plastics are UV-opaque, great care must be taken to ensure that aquarium dividers, specimen holding containers, etc., are UV-transparent or at least to report the types of materials in use.

14-3-3 acts as an intramolecular bridge to regulate cdc25B localization and activity

One of the major regulators of mitosis in somatic cells is cdc25B. cdc25B is tightly regulated at multiple levels. The final activation step involves the regulated binding of 14-3-3 proteins. Previous studies have demonstrated that Ser-323 is a primary 14-3-3 binding site in cdc25B, which influences its activity and cellular localization. 14-3-3 binding to this site appeared to interact with the N-terminal domain of cdc25B to regulate its activity. The presence of consensus 14-3-3 binding sites in the N-terminal domain suggested that the interaction is through direct binding of the 14-3-3 dimer to sites in the N-terminal domain. We have identified Ser-151 and Ser-230 in the N-terminal domain as functional 14-3-3 binding sites utilized by cdc25B in vivo. These low affinity sites cooperate to bind the 14-3-3 dimer bound to the high affinity Ser-323 site, thus forming an intramolecular bridge that constrains cdc25B structure to prevent access of the catalytic site. Loss of 14-3-3 binding to either N-terminal site relaxes cdc25B structure sufficiently to permit access to the catalytic site, and the nuclear export sequence located in the N-terminal domain. Mutation of the Ser-323 site was functionally equivalent to the mutation of all three sites, resulting in the complete loss of 14-3-3 binding, increased access of the catalytic site, and access to nuclear localization sequence.

Contextual binding of p120ctn to E-cadherin at the basolateral plasma membrane in polarized epithelia

E-cadherin-catenin complexes mediate cell-cell adhesion on the basolateral membrane of epithelial cells. The cytoplasmic tail of E-cadherin supports multiple protein interactions, including binding of beta-catenin at the C terminus and of p120(ctn) to the juxtamembrane domain. The temporal assembly and polarized trafficking of the complex or its individual components to the basolateral membrane are not fully understood. In Madin-Darby canine kidney cells at steady state and after treatment with cycloheximide or temperature blocks, E-cadherin and beta-catenin localized to the Golgi complex, but p120ctn was found only at the basolateral plasma membrane. We previously identified a dileucine sorting motif (Leu(586)-Leu(587), termed S1) in the juxtamembrane domain of E-cadherin and now show that it is required to target full-length E-cadherin to the basolateral membrane. Removal of S1 resulted in missorting of E-cadherin mutants (EcadDeltaS1) to the apical membrane; beta-catenin was simultaneously missorted and appeared at the apical membrane. p120(ctn) was not mistargeted with EcadDeltaS1, but could be recruited to the E-cadherin-catenin complex only at the basolateral membrane. These findings help define the temporal assembly and sorting of the E-cadherin-catenin complex and show that membrane recruitment of p120(ctn) in polarized cells is contextual and confined to the basolateral membrane.

Pyramidal cell heterogeneity in the visual cortex of the nocturnal new world owl monkey (aotus trivirgatus)

Recent studies have revealed marked variation in pyramidal cell structure in the visual cortex of macaque and marmoset monkeys. In particular, there is a systematic increase in the size of, and number of spines in, the arbours of pyramidal cells with progression through occipitotemporal (OT) visual areas. In the present study we extend the basis for comparison by investigating pyramidal cell structure in visual areas of the nocturnal owl monkey. As in the diurnal macaque and marmoset monkeys, pyramidal cells became progressively larger and more spinous with anterior progression through OT visual areas. These data suggest that: 1. the trend for more complex pyramidal cells with anterior progression through OT visual areas is a fundamental organizational principle in primate cortex; 2. areal specialization of the pyramidal cell phenotype provides an anatomical substrate for the reconstruction of the visual scene in OT areas; 3. evolutionary specialization of different aspects of visual processing may determine the extent of interareal variation in the pyramidal cell phenotype in different species; and 4. pyramidal cell structure is not necessarily related to brain size. Crown Copyright (C) 2003 Published by Elsevier Science Ltd on behalf of IBRO. All rights reserved.

Dendritic branching of pyramidal cells in the visual cortex of the nocturnal owl monkey: A fractal analysis

The branching structure of neurones is thought to influence patterns of connectivity and how inputs are integrated within the arbor. Recent studies have revealed a remarkable degree of variation in the branching structure of pyramidal cells in the cerebral cortex of diurnal primates, suggesting regional specialization in neuronal function. Such specialization in pyramidal cell structure may be important for various aspects of visual function, such as object recognition and color processing. To better understand the functional role of regional variation in the pyramidal cell phenotype in visual processing, we determined the complexity of the dendritic branching pattern of pyramidal cells in visual cortex of the nocturnal New World owl monkey. We used the fractal dilation method to quantify the branching structure of pyramidal cells in the primary visual area (V1), the second visual area (V2) and the caudal and rostral subdivisions of inferotemporal cortex (ITc and ITr, respectively), which are often associated with color processing. We found that, as in diurnal monkeys, there was a trend for cells of increasing fractal dimension with progression through these cortical areas. The increasing complexity paralleled a trend for increasing symmetry. That we found a similar trend in both diurnal and nocturnal monkeys suggests that it was a feature of a common anthropoid ancestor.

SICV: sistema integrado de comunica????o visual

A necessidade de identificar os blocos e os ambientes de forma que os usu??rios internos e externos n??o tenham dificuldade de encontrar o que precisa. De forma clara e bem especificada mesmo que em alguns casos sejam usadas apenas siglas e n??meros. Assim sendo a comunica????o visual atrav??s de placas ficou din??mica e de f??cil compreens??o