Inhibition of PTPs by H(2)O(2) regulates the activation of distinct MAPK pathways

It has been shown that endogenous production of reactive oxygen species (ROS) during T cell activation regulates signaling events including MAPK activation. Protein tyrosine phosphatases (PTPs) have been regarded as targets of ROS which modify the catalytic cysteine residues of the enzymes. We have analyzed the interplay between the inhibition of PTPs and the activation of MAPK by H(2)O(2). Stimulation of Jurkat T cells with H(2)O(2) induces the phosphorylation of ERK, p38, and JNK members of MAPK family. H(2)O(2) stimulation of T cells was found to inhibit the PTP activity of CD45, SHP-1, and HePTP. Transfection of cells with wtSHP-1 decreased H(2)O(2)-induced ERK and JNK phosphorylation without affecting p38 phosphorylation. Transfection with wtHePTP inhibited H(2)O(2)-induced ERK and p38 phosphorylation without inhibiting JNK phosphorylation. The Src-family kinase inhibitor, PP2, inhibited the H(2)O(2)-induced phosphorylation of ERK, p38, and JNK. The phospholipase C (PLC) inhibitor, U73122, or the protein kinase C (PKC) inhibitor, Ro-31-8425, blocked H(2)O(2)-induced ERK phosphorylation, whereas the same treatment did not inhibit p38 or JNK phosphorylation. Taken together, these results suggest that inhibition of PTPs by H(2)O(2) contributes to the induction of distinct MAPK activation profiles via differential signaling pathways.     

Microtubule plus-ends reveal essential links between intracellular polarization and localized modulation of endocytosis during division-plane establishment in plant cells

Background  

A key event in plant morphogenesis is the establishment of a division plane. A plant-specific microtubular preprophase band (PPB) accurately predicts the line of cell division, whereas the phragmoplast, another plant-specific array, executes cell division by maintaining this predicted line. Although establishment of these specific arrays apparently involves intracellular repolarization events that focus cellular resources to a division site, it still remains unclear how microtubules position the cell division planes. Here we study GFP-AtEB1 decorated microtubule plus-ends to dissect events at the division plane.     

Spatiotemporal dynamics of the spread of African tilapias (Pisces: Oreochromis spp.) into rivers of northeastern Mesoamerica

African tilapias (Oreochromis spp.) occur in more than 100 countries outside of their native ranges and research on their invasions is largely lacking. We investigated spatiotemporal patterns of tilapia spread into 29 drainage basins in Belize and parts of Guatemala and Mexico, drawing on field data and interviews with fishermen. Habitat-suitability models for tilapias were created from geospatial and species occurrence data, and fishermen interviews were used to reconstruct the chronology of tilapia spread into predicted suitable habitats. Tilapia (predominantly Nile tilapia, O. niloticus) presence was confirmed at 78 sites in 9 of 29 drainage basins. Our habitat-suitability model predicted that 7,510 linear km of river habitat in the study area were vulnerable to colonization by tilapias, predominately in mid- to low elevation main stem rivers, from sea level to 277 m above sea level. The reconstructed spatial chronology of spread showed that the invasion started in 1990 and progressed slowly (2 km yr^?1) through an establishment phase before rapid expansion (~30 km yr^?1) between 1996 and 2002, after which new detections slowed. Human movement of fish for aquaculture was identified as a primary cause of dispersal that interacted with flooding as an important secondary cause. The shortest paths across low elevation drainage divides between major basins revealed several potential corridors for future tilapia spread during flooding. Research into tilapia spatial metapopulation structure and economic fisheries status, more stringent regulation of aquaculture activities, pro-active fisheries management, and development of policies to screen potentially invasive species before importation are recommended to avoid additional releases of tilapia and further spread in the region.     

Polymorphisms in the glucocorticoid receptor gene that modulate glucocorticoid sensitivity are associated with rheumatoid arthritis

Introduction  

The glucocorticoid receptor (GR) plays an important regulatory role in the immune system. Four polymorphisms in the GR gene are associated with differences in glucocorticoid (GC) sensitivity; the minor alleles of the polymorphisms N363 S and BclI are associated with relative hypersensitivity to GCs, while those of the polymorphisms ER22/23EK and 9β are associated with relative GC resistance. Because differences in GC sensitivity may influence immune effector functions, we examined whether these polymorphisms are associated with the susceptibility to develop Rheumatoid Arthritis (RA) and RA disease severity.     

Aspects of early arthritis. Definition of disease states in early arthritis: remission versus minimal disease activity

With regard to rheumatoid arthritis, remission as currently used in the literature can have two meanings: either a state with persistent absence of clinical and radiological signs of disease activity without being treated for a specific time period, or it may point to a disease state with minimal disease activity during antirheumatic treatment. A risk factor for the first is absence of autoantibodies, with the anti-CCP-antibodies as best predictors, whereas risk factors for achieving a drug-induced state of minimal disease activity are not well defined. These definitions of remission refer to different disease states; therefore, we propose that the term remission is reserved for patients that are not treated with antirheumatic drugs.     

Gas--liquid chromatography--mass spectrophotometry of hydroxylated octadecanols derived from hydroxylated stearic acids

A gas-liquid chromatographic-mass spectrometric method of determining the position of oxygen atoms on polyfunctional fatty acids has been explored. The method consists of reduction of keto, hydroperoxy, epoxy, and carboxylic acid groups with LiAlH(4) to the corresponding alcohols; trimethylsilylation with bis(trimethylsilyl)acetamide; and analysis by means of the combined gas-liquid chromatograph-mass spectrometer. The following compounds were analyzed: 9-mono-, 9,10-di-, 9,10,12-tri-, and 9,10,12,13-tetrahydroxystearic acids and the corresponding derivatives of octadecan-1-ol. The reduction products of 9,10-epoxystearic acid and a mixture of linoleic acid 9- and 13-hydroperoxides were also analyzed. The position of the oxygen function in the original molecule can be deduced rapidly and accurately.     

Bioaccumulation of selected metals in the gill,liver and muscle tissue of rednose labeo Labeo rosae from two impoundments on the Olifants River,Limpopo river system,South Africa

Metal concentrations in the gill, muscle and liver tissues of Labeo rosae from two impoundments, Loskop and Flag Boshielo dams on the Olifants River, were evaluated in 2011 to detect patterns in metal associations between tissues and impoundments. Elevated concentrations of Ba, Zn, B, Al, Si and Fe, relative to a pristine site in the catchment, were found in the muscle, liver and gill tissues at both impoundments. Molybdenum concentrations were exceptionally high in all tissues at Loskop Dam and in liver at Flag Boshielo Dam. No definite pattern in the ratio metal concentrations within, or between, fish tissues was identified. The expected trend, liver > gills > muscle, was found at both impoundments, but was less prominent at Loskop Dam. Metal concentrations in muscle of Loskop Dam fish were significantly higher than in those at Flag Boshielo Dam. The inverse was true for liver. The long-term impact of elevated metal concentrations on fish health at both impoundments raises concern.     

Regulation of B cell tolerance by murine gangliosides

The potential role of gangliosides as modulators of the triggering of neonatal primary B lymphocytes at the single precursor cell level was evaluated. Tolerance was induced in splenic fragment cultures containing an excess of carrier-primed T cells. Gangliosides at low concentrations (20 ng/culture) abrogated the tolerogenic effect of haptens presented on carriers not recognized by environmental T cells. The permanent arrest of immature B-cell responsiveness resulting from tolerogen treatment was eliminated by the presence of gangliosides during tolerogen treatment. The active moiety in the glycolipid preparation which protected B cells during tolerogen treatment was separated by ion-exchange chromatography and demonstrated to be in the disialoganglioside fraction.     

Practical and reliable FRET/FLIM pair of fluorescent proteins

Background  

In spite of a great number of monomeric fluorescent proteins developed in the recent years, the reported fluorescent protein-based FRET pairs are still characterized by a number of disadvantageous features, complicating their use as reporters in cell biology and for high-throughput cell-based screenings.