The Touch Dome Defines an Epidermal Niche Specialized for Mechanosensory Signaling

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Cytokine profiles in the joint depend on pathology,but are different between synovial fluid,cartilage tissue and cultured chondrocytes

Introduction

This study aimed to evaluate whether profiles of several soluble mediators in synovial fluid and cartilage tissue are pathology-dependent and how their production is related to in vitro tissue formation by chondrocytes from diseased and healthy tissue.

Methods

Samples were obtained from donors without joint pathology (n = 39), with focal defects (n = 65) and osteoarthritis (n = 61). A multiplex bead assay (Luminex) was performed measuring up to 21 cytokines: Interleukin (IL)-1α, IL-1β, IL-1RA, IL-4, IL-6, IL-6Rα, IL-7, IL-8, IL-10, IL-13, tumor necrosis factor (TNF)α, Interferon (IFN)γ, oncostatin M (OSM), leukemia inhibitory factor (LIF), adiponectin, leptin, monocyte chemotactic factor (MCP)1, RANTES, basic fibroblast growth factor (bFGF), hepatocyte growth factor (HGF), vascular growth factor (VEGF).

Results

In synovial fluid of patients with cartilage pathology, IL-6, IL-13, IFNγ and OSM levels were higher than in donors without joint pathology (P ≤0.001). IL-13, IFNγ and OSM were also different between donors with cartilage defects and OA (P <0.05). In cartilage tissue from debrided defects, VEGF was higher than in non-pathological or osteoarthritic joints (P ≤0.001). IL-1α, IL-6, TNFα and OSM concentrations (in ng/ml) were markedly higher in cartilage tissue than in synovial fluid (P <0.01). Culture of chondrocytes generally led to a massive induction of most cytokines (P <0.001). Although the release of inflammatory cytokines was also here dependent on the pathological condition (P <0.001) the actual profiles were different from tissue or synovial fluid and between non-expanded and expanded chondrocytes. Cartilage formation was lower by healthy unexpanded chondrocytes than by osteoarthritic or defect chondrocytes.

Conclusions

Several pro-inflammatory, pro-angiogenic and pro-repair cytokines were elevated in joints with symptomatic cartilage defects and/or osteoarthritis, although different cytokines were elevated in synovial fluid compared to tissue or cells. Hence a clear molecular profile was evident dependent on disease status of the joint, which however changed in composition depending on the biological sample analysed. These alterations did not affect in vitro tissue formation with these chondrocytes, as this was at least as effective or even better compared to healthy chondrocytes.     

Concordant evolution of plumage colour, feather microstructure and a melanocortin receptor gene between mainland and island populations of a fairy-wren

Studies of the patterns of diversification of birds on islands have contributed a great deal to the development of evolutionary theory. In white-winged fairy-wrens, Malurus leucopterus, mainland males develop a striking blue nuptial plumage whereas those on nearby islands develop black nuptial plumage. We explore the proximate basis for this divergence by combining microstructural feather analysis with an investigation of genetic variation at the melanocortin-1 receptor locus (MC1R). Fourier analysis revealed that the medullary keratin matrix (spongy layer) of the feather barbs of blue males was ordered at the appropriate nanoscale to produce the observed blue colour by coherent light scattering. Surprisingly, the feather barbs of black males also contained a spongy layer that could produce a similar blue colour. However, black males had more melanin in their barbs than blue males, and this melanin may effectively mask any structural colour produced by the spongy layer. Moreover, the presence of this spongy layer suggests that black island males evolved from a blue-plumaged ancestor. We also document concordant patterns of variation at the MC1R locus, as five amino acid substitutions were perfectly associated with the divergent blue and black plumage phenotypes. Thus, with the possible involvement of a melanocortin receptor locus, increased melanin density may mask the blue-producing microstructure in black island males, resulting in the divergence of plumage coloration between mainland and island white-winged fairy-wrens. Such mechanisms may also be responsible for plumage colour diversity across broader geographical and evolutionary scales.     

Carotenoid‐based plumage coloration in golden‐crowned kinglets Regulus satrapa: pigment characterization and relationships with migratory timing and condition

Carotenoid‐based ornamental coloration has long been proposed to honestly signal quality due to its dependence on individual condition. Because migration can be one of the most stressful periods of an animal's annual cycle, developing colourful plumage may be particularly challenging for species in which migration and moult periods overlap or occur sequentially. The purpose of this study was to investigate pigmentary and condition‐dependent bases of carotenoid colour variation in a small migratory passerine, the golden‐crowned kinglet Regulus satrapa (Family Regulidae). We captured 186 male and female kinglets of various ages during fall migration in southwestern Ontario, Canada and recorded arrival date, body condition index, fat and pectoral muscle scores, wing mite infestation, and feather growth rate as measures of condition. We quantified crown coloration using reflectance spectrometry and analyzed feather carotenoids using high‐performance liquid chromatography. Yellow crown feathers of female kinglets contained only yellow hydroxycarotenoids, whereas orange feathers of males harboured a suite of eight carotenoid pigments. Males with longer wavelength orange crown hues deposited greater concentrations of ketocarotenoids, especially canthaxanthin. Female kinglets with longer wavelength crown hues and males with longer wavelength crown hues and more saturated crown coloration left for migration earlier in the year. Females with longer wavelength crown hues had fewer feather mites and tended to be in better condition. However, male kinglets with more saturated coloration possessed smaller pectoral muscles. This is the first study to identify plumage carotenoids in this North American bird family and to determine the pigmentary basis for both inter‐ and intrasexual colour variation. Our results provide further support for the condition‐dependence of carotenoid coloration and suggest that ornamental elaboration in both sexes may encode information about fall condition and migratory performance.     

Identification of low molecular weight GTP-binding proteins and their sites of interaction in subcellular fractions from skeletal muscle

The presence of low molecular weight GTP-binding proteins was investigated in subcellular fractions from skeletal muscle. Skeletal muscle homogenate, transverse tubules, triads, sarcoplasmic reticulum membranes, and cytosol fractions were separated in sodium dodecyl sulfate-gel electrophoresis and blotted onto nitrocellulose. The presence of GTP-binding proteins was explored by incubation of these blots with [alpha-32P] GTP. GTP labeled two polypeptides of Mr = 23,000 and 29,000 in all the fractions examined. Binding of [alpha-32P]GTP was specific and dependent on Mg2+. The 23-kDa polypeptide was labeled to a higher extent with [alpha-32P]GTP than the 29-kDa polypeptide, although both were enriched in transverse tubule fractions. A GTP-binding polypeptide of 40 kDa was also enriched in transverse tubule preparations and identified as Gi alpha by immunostaining with anti-Gi alpha. Using a blot overlay approach and [alpha-32P]GTP-labeled cytosolic components, several polypeptides were identified that interact with the 23- and 29-kDa GTP-binding proteins. Among these components were polypeptides of Mr = 60,000, 47,000, 44,000, 42,000, and 38,000, which were mainly of cytosolic origin but also associated with triads and transverse tubule membranes. The 47-, 44-, 42-, and 38-kDa polypeptides were found to be structurally related to the glycolytic enzymes enolase, 3-phosphoglyceric phosphokinase, aldolase, and glycoeraldehyde-3-phosphate dehydrogenase, respectively. The purified glycolytic enzymes specifically bound the 23- and 29-kDa GTP-binding proteins under both denaturing and nondenaturing conditions. The association of the GTP-binding proteins with these polypeptides was resistant to detergents such as 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (CHAPS), Triton X-100, and Tween. A 23-kDa GTP-binding protein purified from chromaffin cells bound to a 157-kDa polypeptide in triads and chromaffin cell membranes. The 157-kDa polypeptide was a minor component in these membranes and not related to the subunits of the dihydropyridine receptor. In view of the proposed function of low molecular weight GTP-binding proteins in processes such as membrane communication and secretion coupling, the association of these proteins with transverse tubules and triads in skeletal muscle is discussed in terms of a role in signal transmission.