Localization and phenotypical characterization of murine macrophages

The aim of the experimental work described in this thesis is to localize and characterize phenotypically the distinct macrophage sub populations present in murine organs in detail. To this end an immunohistochemical approach was chosen. A panel of macrophage and dendrocyte-specific monoclonal antibodies was used and their staining pattern in various murine organs was investigated

Fulmar Litter EcoQO Monitoring in the Netherlands 1979 - 2007 in relation to EU Directive 2000/59/EC on Port Reception Facilities

Operational and cargo related wastes from ships are an important source of litter in the marine environment in the southern North Sea and cause serious economical and ecological damage. Marine litter monitoring program using plastic abundance in stomachs of a seabird, the Northern Fulmar, was already operational in The Netherlands and was further developed also for international implementation by OSPAR as one of the 'Ecological Quality Objectives (EcoQOs)' for the North Sea (OSPAR 2008). Fulmars are purely oceanic foragers, ingest all sorts of litter from the sea surface, and do not regurgitate poorly degrading diet components, but slowly wear these down in the stomach. Accumulated hard plastic items in stomachs of beached Fulmars thus integrate marine litter levels encountered over a number of weeks in a particular area

An atomic force microscope operating at hypergravity for in situ measurement of cellular mechano-response

We present a novel atomic force microscope (AFM) system, operational in liquid at variable gravity, dedicated to image cell shape changes of cells in vitro under hypergravity conditions. The hypergravity AFM is realized by mounting a stand-alone AFM into a large-diameter centrifuge. The balance between mechanical forces, both intra- and extracellular, determines both cell shape and integrity. Gravity seems to be an insignificant force at the level of a single cell, in contrast to the effect of gravity on a complete (multicellular) organism, where for instance bones and muscles are highly unloaded under near weightless (microgravity) conditions. However, past space flights and ground based cell biological studies, under both hypogravity and hypergravity conditions have shown changes in cell behaviour (signal transduction), cell architecture (cytoskeleton) and proliferation. Thus the role of direct or indirect gravity effects at the level of cells has remained unclear. Here we aim to address the role of gravity on cell shape. We concentrate on the validation of the novel AFM for use under hypergravity conditions. We find indications that a single cell exposed to 2 to 3 × g reduces some 30–50% in average height, as monitored with AFM. Indeed, in situ measurements of the effects of changing gravitational load on cell shape are well feasible by means of AFM in liquid. The combination provides a promising technique to measure, online, the temporal characteristics of the cellular mechano-response during exposure to inertial forces

Age-dependent deamidation of αB-crystallin

AbstractBovine and human αB-crystallin undergo deamidation upon aging in the lens. In bovine αB-crystallin, the specific site of dearnidation has been identified by peptide mapping after tryptic digestion. Asn-146 was found to be subject to deamidation, whereas the only other asparagine residue, at position 78, is not affected. Asn-146 is flanked at the carboxylic side by a glyeyl residue. Yet, the rate of in vivo deamidation is low. In vitro studies reveal that the deamidation is accompanied by significant racemization, indicating that the deamidation proceeds via formation of a succinimide intermediate

Activin is produced by rat Sertoli cells in vitro and can act as an autocrine regulator of Sertoli cell function

Regulation of androgen receptor (AR) mRNA expression was studied in Sertoli cells and peritubular myoid cells isolated from immature rat testis, and in the lymph node carcinoma cell line derived from a human prostate (LNCaP). Addition of dibutyryl-cyclic AMP (dbcAMP) to Sertoli cell cultures resulted in a rapid transient decrease in AR mRNA expression (5 h), which was followed by a gradual increase in AR mRNA expression (24-72 h). This effect of dbcAMP mimicked follicle-stimulating hormone (FSH) action. In peritubular myoid cells, there was only a moderate but prolonged decrease during incubation in the presence of dbcAMP, and in LNCaP cells no effect of dbcAMP on AR mRNA expression was observed. When Sertoli cells or peritubular myoid cells were cultured in the presence of androgens, AR mRNA expression in these cell types did not change. This is in contrast to LNCaP cells, that showed a marked reduction of AR mRNA expression during androgen treatment. In the present experiments, transcriptional regulation of AR gene expression in Sertoli cells and LNCaP cells was also examined. Freshly isolated Sertoli cell clusters were transfected with a series of luciferase reporter gene constructs, driven by the AR promoter. It was found that addition of dbcAMP to the transfected Sertoli cells resulted in a small but consistent increase in reporter gene expression (which was interpreted as resulting from AR promoter activity); a construct that only contained the AR 5' untranslated region of the cDNA sequence did not show such a regulation. The same constructs, transfected into LNCaP cells, did not show any transcriptional down-regulation when the synthetic androgen R1881 was added to the cell cultures. A nuclear transcription elongation experiment (run-on), however, demonstrated that androgen-induced AR mRNA down-regulation in LNCaP cells resulted from an inhibition of AR gene transcription. The present results indicate that in Sertoli cells and LNCaP cells, hormonal effects on AR gene transcription play a role in regulation of AR expression. However, AR gene transcription in these cells is differentially regulated