Reversible phytochrome regulation influenced the severity of ozone-induced visible foliar injuries in Trifolium subterraneum L.

In Trifolium subterraneum, oxidative stress caused by ozone has been shown to result in more severe visible foliar injuries when plants were kept in dim broadband white light during the night (i.e. a long photoperiod) compared to darkness during the night (a short photoperiod). As phytochrome signalling is involved in photoperiod sensing, the effect of night-time red and far-red illumination on the ozone-induced response was studied. T. subterraneum plants were treated with ozone enriched air (70?ppb) for either 1?h for a single day or 6?h for three consecutive days. After the first ozone exposure, plants were separated into six night-time light regimes during the two subsequent nights (10?h?day, 14?h night): (1) darkness, (2) far-red light (FR), (3) a short night-break of red followed by far-red light during an otherwise dark night (R FR), (4) a short night-break of red, far-red and finally red light during an otherwise dark night (R FR R), (5) dim white light (L) and (6) red light (R). The treatments L and R resulted in significantly more severe ozone-induced visible foliar injuries relative to D and FR treatments, indicating a phytochrome-mediated response. The night-breaks resulted in a photoreversible and significantly different ozone response depending on the light quality of the last light interval (R FR or R FR R), supporting a photoreversible (between P_r and P_fr) phytochrome signalling response. Thus, in T. subterraneum, the outcome of oxidative stress due to ozone appears to depend on the photoperiod mediated by the night-time conformation of phytochrome.     

Modulation of Leishmania major aquaglyceroporin activity by a mitogen-activated protein kinase

Leishmania major aquaglyceroporin (LmjAQP1) adventitiously facilitates the uptake of antimonite [Sb(III)], an active form of Pentostam® or Glucantime®, which are the first line of defence against all forms of leishmaniasis. The present paper shows that LmjAQP1 activity is modulated by the mitogen‐activated protein kinase, LmjMPK2. Leishmania parasites coexpressing LmjAQP1 and LmjMPK2 show increased Sb(III) uptake and increased Sb(III) sensitivity. When subjected to a hypo‐osmotic stress, these cells show faster volume recovery than cells expressing LmjAQP1 alone. LmjAQP1 is phosphorylated in vivo at Thr‐197 and this phosphorylation requires LmjMPK2 activity. Lys‐42 of LmjMPK2 is critical for its kinase activity. Cells expressing altered T197A LmjAQP1 or K42A LmjMPK2 showed decreased Sb(III) influx and a slower volume recovery than cells expressing wild‐type proteins. Phosphorylation of LmjAQP1 led to a decrease in its turnover rate affecting LmjAQP1 activity. Although LmjAQP1 is localized to the flagellum of promastigotes, upon phosphorylation, it is relocalized to the entire surface of the parasite. Leishmania mexicana promastigotes with an MPK2 deletion showed reduced Sb(III) uptake and slower volume recovery than wild‐type cells. This is the first report where a parasite aquaglyceroporin activity is post‐translationally modulated by a mitogen‐activated protein kinase.     

Bone formation rather than inflammation reflects Ankylosing Spondylitis activity on PET-CT: a pilot study

Introduction

Positron Emission Tomography - Computer Tomography (PET-CT) is an interesting imaging technique to visualize Ankylosing Spondylitis (AS) activity using specific PET tracers. Previous studies have shown that the PET tracers [¹⁸F]FDG and [¹¹C](R)PK11195 can target inflammation (synovitis) in rheumatoid arthritis (RA) and may therefore be useful in AS. Another interesting tracer for AS is [¹⁸F]Fluoride, which targets bone formation. In a pilot setting, the potential of PET-CT in imaging AS activity was tested using different tracers, with Magnetic Resonance Imaging (MRI) and conventional radiographs as reference.

Methods

In a stepwise approach different PET tracers were investigated. First, whole body [¹⁸F]FDG and [¹¹C](R)PK11195 PET-CT scans were obtained of ten AS patients fulfilling the modified New York criteria. According to the BASDAI five of these patients had low and five had high disease activity. Secondly, an extra PET-CT scan using [¹⁸F]Fluoride was made of two additional AS patients with high disease activity. MRI scans of the total spine and sacroiliac joints were performed, and conventional radiographs of the total spine and sacroiliac joints were available for all patients. Scans and radiographs were visually scored by two observers blinded for clinical data.

Results

No increased [¹⁸F]FDG and [¹¹C](R)PK11195 uptake was noticed on PET-CT scans of the first 10 patients. In contrast, MRI demonstrated a total of five bone edema lesions in three out of 10 patients. In the two additional AS patients scanned with [¹⁸F]Fluoride PET-CT, [¹⁸F]Fluoride depicted 17 regions with increased uptake in both vertebral column and sacroiliac joints. In contrast, [¹⁸F]FDG depicted only three lesions, with an uptake of five times lower compared to [¹⁸F]Fluoride, and again no [¹¹C](R)PK11195 positive lesions were found. In these two patients, MRI detected nine lesions and six out of nine matched with the anatomical position of [¹⁸F]Fluoride uptake. Conventional radiographs showed structural bony changes in 11 out of 17 [¹⁸F]Fluoride PET positive lesions.

Conclusions

Our PET-CT data suggest that AS activity is reflected by bone activity (formation) rather than inflammation. The results also show the potential value of PET-CT for imaging AS activity using the bone tracer [¹⁸F]Fluoride. In contrast to active RA, inflammation tracers [¹⁸F]FDG and [¹¹C](R)PK11195 appeared to be less useful for AS imaging.     

Development of electrochemiluminescence-based singleplex and multiplex assays for the quantification of α-synuclein and other proteins in cerebrospinal fluid

The need for improved diagnostic accuracy and markers of progression in neurodegenerative diseases motivates the identification of objective biomarkers as well as optimized assays for their quantification. Several potential marker candidates for Parkinson's disease (PD) in cerebrospinal fluid have been identified. These include α-synuclein, a major constituent of the intracellular aggregates. We give a general overview and details of our experience in converting established enzyme-linked immunoabsorbent assays (for α-synuclein and other proteins) onto an electrochemiluminescence-based platform as well as considerations on multiplexing different assays for PD.     

Leukemia inhibitory factor deficiency modulates the immune response and limits autoimmune demyelination: a new role for neurotrophic cytokines in neuroinflammation

The neurotrophic cytokines ciliary neurotrophic factor and leukemia inhibitory factor (LIF) play a key role in neuronal and oligodendrocyte survival and as protective factors in neuroinflammation. To further elucidate the potential of endogenous LIF in modulating neuroinflammation, we studied myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis in LIF knockout mice (LIF(-/-) mice). In the late phase of active myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis, LIF(-/-) mice exhibited a markedly milder disease course. The inflammatory infiltrate in LIF(-/-) mice was characterized by an increase in neutrophilic granulocytes early and fewer infiltrating macrophages associated with less demyelination later in the disease. In good correlation with an effect of endogenous LIF on the immune response, we found an Ag-specific T cell-priming defect with impaired IFN-gamma production in LIF(-/-) mice. On the molecular level, the altered recruitment of inflammatory cells is associated with distinct patterns of chemokine production in LIF(-/-) mice with an increase of CXCL1 early and a decrease of CCL2, CCL3, and CXCL10 later in the disease. These data reveal that endogenous LIF is an immunologically active molecule in neuroinflammation. This establishes a link between LIF and the immune system which was not observed in the ciliary neurotrophic factor knockout mouse.     

Integrating two physiological approaches helps relate respiration to growth of Pinus radiata

Correlation methods originating in the growth and maintenance paradigm (GMP) are traditionally used to calculate a 'growth coefficient' (g) or the 'growth potential' (1/g) of entire plants. The enthalpy balance approach is usually applied to plant organs and relies on determination of both CO(2) release and O(2) reduction to provide a measure of instantaneous rates of enthalpic growth (R(SG)DeltaH(B)). Aspects of both the approaches to explore physiological mechanisms that govern enthalpic growth (variation in rates of CO(2) release versus rates of O(2) reduction) were combined. Respiration and growth rates of apical buds of Pinus radiata were affected strongly by canopy position, and moderately by branching order. A linear relation between enthalpic growth and CO(2) respiration explained 69% of the observed variation. Despite faster rates of growth, enthalpic growth potential (1/g(H)) was comparatively low in the upper canopy. Low enthalpic growth potential entailed comparatively low enthalpy conversion efficiency (eta(H), ratio of R(SG)DeltaH(B) to R(CO(2)) DeltaH(CO(2)); proportional to CO(2):O(2) and to carbon conversion efficiency epsilon) at large R(SG)DeltaH(B). Maximizing enthalpic growth requires a large capacity for O(2) reduction. Relations between R(SG)DeltaH(B) and eta(H) could be described by hyperbolae using two parameters. One parameter, P(1), is equivalent to enthalpic growth potential (1/g(H)).     

Distinct signal transduction processes by IL-4 and IL-13 and influences from the Q551R variant of the human IL-4 receptor alpha chain

Background  

Although IL-4 and IL-13 share the IL-13 receptor, IL-13 exhibits unique functions. To elicit the cellular basis of these differences, signal transduction processes have been compared. Additionally, the role of the IL-4 receptor alpha (IL-4Rα) variant Q551R was investigated.