GDF5 reduces MMP13 expression in human chondrocytes via DKK1 mediated canonical Wnt signaling inhibition.

OBJECTIVE: Growth differentiation factor 5 (GDF5) is important for joint formation and associated with osteoarthritis (OA). Its role for the homeostasis of cartilage extracellular matrix (ECM) is, however, unknown. The canonical Wnt signaling pathway is also implemented in OA and activation of the pathway has detrimental effects on the cartilage ECM. The objective of this study was to investigate the effect of GDF5 stimulation on the Wnt signaling pathway and on the expression of known modulators of cartilage ECM. DESIGN: Human chondrocytes were cultured in the pellet mass system and stimulated with increasing concentrations of GDF5. Expression of matrix modulating enzymes and canonical Wnt inhibitors dickkopf 1 (DKK1) and frizzled related protein (FRZB) were measured with quantitative PCR (qPCR). Protein levels of matrix metalloprotease 13 (MMP13), DKK1 and ß-catenin were measured with enzyme-linked immunosorbent assay (ELISA). Canonical Wnt signaling was stimulated with Wnt3a and small molecule CHIR-99021 and DKK1 was blocked with small molecule WAY-262611. RESULTS: In this study, we show that GDF5 stimulation of human chondrocytes inhibits expression of the cartilage ECM degrading enzymes MMP13 and ADAMTS4 and stimulates the expression of cartilage anabolic genes ACAN and SOX9. We further show that the stimulation inhibits the canonical Wnt signaling pathway through expression of the canonical Wnt inhibitors DKK1 and FRZB. Finally we show that inhibition of MMP13 expression through GDF5 stimulation is mediated by DKK1. CONCLUSION: Herein, we provide evidence of a previously unknown link between GDF5 signaling and canonical Wnt signaling that may contribute to the understanding of the molecular mechanisms of OA.

Targeted resequencing of candidate genes using selector probes.

Targeted genome enrichment is a powerful tool for making use of the massive throughput of novel DNA-sequencing instruments. We herein present a simple and scalable protocol for multiplex amplification of target regions based on the Selector technique. The updated version exhibits improved coverage and compatibility with next-generation-sequencing (NGS) library-construction procedures for shotgun sequencing with NGS platforms. To demonstrate the performance of the technique, all 501 exons from 28 genes frequently involved in cancer were enriched for and sequenced in specimens derived from cell lines and tumor biopsies. DNA from both fresh frozen and formalin-fixed paraffin-embedded biopsies were analyzed and 94% specificity and 98% coverage of the targeted region was achieved. Reproducibility between replicates was high (R(2) = 0, 98) and readily enabled detection of copy-number variations. The procedure can be carried out in <24 h and does not require any dedicated instrumentation.

Host species critical for offspring fitness and sex ratio for an oligophagous parasitoid: implications for host coexistence.

In theory, inferior apparent competitors sharing a natural enemy with superior apparent competitors should be excluded in the absence of stabilising factors. Nevertheless, plentiful examples of coexisting apparent competitors exist. In this paper, we show that parasitoid resource competition within hosts affects both parasitoid sex ratio and female body size, with implication for population growth and apparent competition between the two closely related hosts experiencing a strong asymmetry in their interaction. While the superior competitor delivers parasitoids with higher fitness to the shared parasitoid pool, the inferior competitor delivers a higher proportion of female parasitoids. Hence, the inferior host experience an inflow of fit parasitoids from the superior competitor, which should increase the risk of exclusion, but also an outflow of parasitoid females, which should reduce the risk of exclusion and increase stability. We conclude that differential outcomes of parasitoid resource competition in different host species may have profound effects on shared parasitoid populations and should be included in future studies of apparent competition between hosts.

Disperse--a software system for design of selector probes for exon resequencing applications.

SUMMARY: Selector probes enable the amplification of many selected regions of the genome in multiplex. Disperse is a software pipeline that automates the procedure of designing selector probes for exon resequencing applications. AVAILABILITY: Software and documentation is available at http://bioinformatics.org/disperse

Assessing state-wide biodiversity in the Florida Gap analysis project.

The Florida Gap (Fl-Gap) project provides an assessment of the degree to which native animal species and natural communities are or are not represented in existing conservation lands. Those species and communities not adequately represented in areas being managed for native species constitute 'gaps' in the existing network of conservation lands. The United States Geological Survey Gap Analysis Program is a national effort and so, eventually, all 50 states will have completed it. The objective of Fl-Gap was to provide broad geographic information on the status of terrestrial vertebrates, butterflies, skippers and ants and their respective habitats to address the loss of biological diversity. To model the distributions and potential habitat of all terrestrial species of mammals, breeding birds, reptiles, amphibians, butterflies, skippers and ants in Florida, natural land cover was mapped to the level of dominant or co-dominant plant species. Land cover was classified from Landsat Thematic Mapper (TM) satellite imagery and auxiliary data such as the national wetlands inventory (NWI), soils maps, aerial imagery, existing land use/land cover maps, and on-the-ground surveys. Wildlife distribution models were produced by identifying suitable habitat for each species within that species' range. Mammalian models also assessed a minimum critical area required for sustainability of the species' population. Wildlife species richness was summarized against land stewardship ranked by an area's mandates for conservation protection.

Pyrometric measurement of the temperature and size of individual combusting fuel particles.

A two-color pyrometric technique was developed for the in situ simultaneous measurement of individual fuel-particle temperatures and sizes in a pressurized entrained flow reactor (PEFR). A method that requires only a single optical port was developed, and a specially designed optical probe was manufactured for the measurements at the PEFR. The fuel-particle temperature was obtained by applying two-color pyrometry. The particle size was determined from the same pyrometric signals. A discrimination method was developed to confirm that the detected particle was valid for particle sizing. Several series of measurements were made at a PEFR at different process conditions, and some typical results are shown.

Analysis of pollutant chemistry in combustion by in situ pulsed photoacoustic laser diagnostics.

A technique for gas analysis based on pulsed-laser-induced photoacoustic spectroscopy in the UV and the visible is presented. The laser-based technique and the associated analysis probe have been developed for the analysis of pollutant chemistry in fluidized beds and other combustion environments with limited or no optical access. The photoacoustic-absorption spectrum of the analyzed gas is measured in a test cell located at the end of a tubular probe. This test cell is subject to the prevailing temperature and pressure in the combustion process. The instrument response has been calibrated for N(2)O, NO, NO(2), NH(3), SO(2), and H(2)S at atmospheric pressure between 20 and 910 °C. The response of the probe was found to increase with pressure for N(2)O, NO, NH(3), and NO(2) up to 1.2 MPa pressure. The method and the probe have been used for detection and ranging of gas concentrations in a premixed methane flame. Some preliminary tests in a large 12-MW circulating bed boiler have also been done.