Monocyte cholesterol homeostasis correlates with the presence of detergent resistant membrane microdomains.

BACKGROUND: Lipid membrane microdomains are involved in the regulation of biological functions of monocyte membrane proteins. These microdomains show a relative resistance to non-ionic detergents providing an easy analytical tool to study them. METHODS: Here, we applied a rapid detergent-based flow cytometric assay to investigate microdomain association of proteins on monocytes from whole blood samples. The association of known surface antigens with detergent resistant fraction of membranes (DRMs) was compared using monocytes from healthy blood donors, patients with genetic disorders affecting cellular cholesterol traffic and patients with systemic inflammatory response. RESULTS: All investigated surface antigens of Niemann-Pick type C (NPC)-mutant monocytes with impaired cholesterol influx and defective late endosome cholesterol trafficking, presented a strongly increased DRM-association. Though, membrane antigens of ATP binding cassette transporter A1 (ABCA1)-mutant monocytes with impaired cholesterol efflux did not show alterations in DRM-association. Differential CD14-dependent receptor clustering within microdomains was also investigated in response to in vivo lipopolysaccharide (LPS) and/or atherogenic lipoprotein activation. Increased DRM-association of the GPI-anchored proteins CD14, CD55, the Fcgamma receptor CD64, the scavenger receptors CD36, CD91 and CD163, the integrin CD11a, and complement receptor 3 complex CD11b/CD18 were observed from patients with systemic inflammatory response syndrome (SIRS)/sepsis or coronary artery disease (CAD)/myocardial infarction. Interestingly, the tetraspanin CD81 presented increased DRM-association in SIRS/sepsis patients, but not in CAD patients. Moreover, the pentaspanin CD47 and the Fcgamma RIII CD16 showed an increased DRM partition in CAD patients but disassembled from DRMs in SIRS/sepsis patients. CONCLUSIONS: Our results demonstrate that flow cytometric analysis of short time in situ detergent extraction provides a powerful tool for rapid screening of blood monocyte DRMs to preselect patients with potential raft/microdomain abnormalities for more detailed analysis.     

Species diversity in Gymnogeophagus (Teleostei: Cichlidae) and comparative biogeography of cichlids in the Middle Paraná basin,an emerging hotspot of fish endemism

Hydrobiologia - We address the diversity of two species groups of the cichlid genus Gymnogeophagus in the Middle Paraná basin using molecular phylogeography and traditional morphological...     

Opposite fates of the purine metabolite allantoin under water and nitrogen limitations in bread wheat

Plant Molecular Biology - Degradation of nitrogen-rich purines is tightly and oppositely regulated under drought and low nitrogen supply in bread wheat. Allantoin is a key target metabolite for...     

Sulfated hyaluronic acid and dexamethasone possess a synergistic potential in the differentiation of osteoblasts from human bone marrow stromal cells

The development of novel bioactive biomaterials is urgently needed to meet the needs of an aging population. Both sulfated hyaluronic acid and dexamethasone are candidates for the functionalization of bone grafts, as they have been shown to enhance the differentiation of osteoblasts from bone marrow stromal cells in vitro and in vivo. However, the underlying mechanisms are not fully understood. Furthermore, studies combining different approaches to assess synergistic potentials are rare. In this study, we aim to gain insights into the mode of action of both sulfated hyaluronic acid and dexamethasone by a comprehensive analysis of the cellular fraction, released matrix vesicles, and the extracellular matrix, combining classical biochemical assays with mass spectrometry–based proteomics, supported by novel bioinformatical computations. We found elevated differentiation levels for both treatments, which were further enhanced by a combination of sulfated hyaluronic acid and dexamethasone. Single treatments revealed specific effects on osteogenic differentiation. Dexamethasone activates signalling pathways involved in the differentiation of osteoblasts, for example, CXC-motif chemokine receptor type 4 and mitogen-activated protein kinases. The effects of sulfated hyaluronic acid were predominantly linked to an alteration in the composition of the extracellular matrix, affecting the synthesis, secretion, and/or activity of fibrillary (fibronectin and thrombospondin-2) and nonfibrillary (transglutaminase-2, periostin, and lysyloxidase) extracellular matrix components, including proteases and their inhibitors (matrix metalloproteinase-2, tissue inhibitor of metalloproteinase-3). The effects were treatment specific, and less additive or contrary effects were found. Thus, we anticipate that the synergistic action of the treatment-specific effects is the key driver in elevated osteogenesis.     

Organic fertilization changes the response of mycelium of arbuscular mycorrhizal fungi and their sporulation to mineral NPK supply

The synergetic effect of organic (cow manure) and mineral fertilization on the development arbuscular mycorrhizal (AM) fungi was demonstateded. The length of AM mycelium and sporulation were used as sensitive markers of the physiological state of soil AM fungal population. In manured treatments, both parameters increased in proportion with increasing mineral fertilization. In unmanured soil, the opposite trend was observed for the length of AM hyphae, which decreased with increasing mineral fertilization. Correlation analysis showed the dependence of length of AM hyphae and sporulation on soil available phosphorus. The correlation was negative in soil with no mineral fertilization and positive in soil supplied with luxury doses of mineral fertilizer.     

Transport and utilization of rhizoferrin bound iron in Mycobacterium smegmatis

Transport and metabolization of iron bound to the fungal siderophore rhizoferrin was analyzed by transport kinetics, Mössbauer and EPR spectroscopy. Saturation kinetics (v _max=24.4 pmol/(mg min), K _m=64.4M) and energy dependence excluded diffusion and provided evidence for a rhizoferrin transport system in M. smegmatis. Based on the spectroscopic techniques indications for intracellular presence of the ferric rhizoferrin complex were found. This feature could be of practical importance in the search of novel drugs for the treatment of mycobacterial infections. EPR and Mössbauer spectroscopy revealed different ferritin mineral cores depending on the siderophore iron source. This finding was interpreted in terms of different protein shells, i.e. two types of ferritins.     

Changes in EEG Power Spectra During Biofeedback of Slow Cortical Potentials in Epilepsy

The goal of the study was to explore parallel changes in EEG spectral frequencies during biofeedback of slow cortical potentials (SCPs) in epilepsy patients. Thirty-four patients with intractable focal epilepsy participated in 35 sessions of SCP self-regulation training. The spectral analysis was carried out for the EEG recorded at the same electrode site (Cz) that was used for SCP feedback. The most prominent effect was the increase in the 2 power (6.0–7.9 Hz) and the relative power decrement in all other frequency bands (particularly 1, 2, and 2) in transfer trials (i.e., where patients controlled their SCPs without continuous feedback) compared with feedback trials. In the second half of the training course (i.e., sessions 21–35) larger power values in the , , and bands were found when patients were required to produce positive versus negative SCP shifts. Both across-subject and across-session (within-subject) correlations between spectral EEG parameters, on the one hand, and SCP data, on the other hand, were low and inconsistent, contrary to high and stable correlations between different spectral variables. This fact, as well as the lack of considerable task-dependent effects during the first part of training, indicates that learned SCP shifts did not directly lead to the specific dynamics of the EEG power spectra. Rather, these dynamics were related to nonspecific changes in patients' brain state.