Oxidative changes of lipids monitored by MALDI MS

Oxidation processes of lipids are of paramount interest from many viewpoints. For instance, oxidation processes are highly important under in vivo conditions because molecules with regulatory functions are generated by oxidation of lipids or free fatty acids. Additionally, many inflammatory diseases are accompanied by lipid oxidation and, therefore, oxidation products are also useful disease (bio)markers. Thus, there is also considerable interest in methods of (oxidized) lipid analysis.Nowadays, soft ionization mass spectrometric (MS) methods are regularly used to study oxidative lipid modifications due to their high sensitivities and the extreme mass resolution. Although electrospray ionization (ESI) MS is so far most popular, applications of matrix-assisted laser desorption and ionization (MALDI) MS are increasing. This review aims to summarize the so far available data on MALDI analyses of oxidized lipids. In addition to model systems, special attention will be paid to the monitoring of oxidized lipids under in vivo conditions, particularly the oxidation of (human) lipoproteins. It is not the aim of this review to praise MALDI as the “best” method but to provide a critical survey of the advantages and drawbacks of this method.     

Oxygen and cytokine-dependent changes in choline phospholipid saturation in hematopoietic progenitor cells detected by MALDI-TOF mass spectrometry

The adaptation of cells to a changing environment is normally accompanied by rapid and/or chronic remodeling of membrane lipids. In order to understand the role played by membrane lipid metabolism in such responses, it is necessary to characterize in more detail the changes in membrane composition occurring in response to defined stimuli. There has been intense interest in characterizing the “stem cell niche” in recent years and an emerging consensus that stem cells are located in regions of low oxygen tension and probably well-isolated from the blood supply.We report here the use of matrix-assisted laser desorption and ionization time-of-flight mass spectrometry to monitor changes in the composition and saturation degree of choline phospholipids of hematopoietic progenitor (FDCPmix) cells under standard nutrient-rich culture conditions and at low oxygen and low glucose concentrations. We found that the increase in proliferation rate driven by high concentrations of interleukin-3 (IL-3) is associated with a decrease in membrane phosphatidylcholine (PC) 18:0/20:4 and sphingomyelin (SM) together with an increase in PC 18:0/18:2 and dihydro SM. Furthermore, this effect is most pronounced under low oxygen and low glucose conditions, independent of cell proliferation rates.     

Microbial nitrate respiration--genes, enzymes and environmental distribution

Nitrate is a key node in the network of the assimilatory and respiratory nitrogen pathways. As one of the ‘fixed’ forms of nitrogen, nitrate plays an essential role in both nature and industry. For bacteria, it is both a nitrogen source and an electron acceptor. In agriculture and wastewater treatment, nitrate respiration by microorganisms is an important issue with respect to economics, greenhouse gas emission and public health. Several microbial processes compete for nitrate: denitrification, dissimilatory nitrate reduction to ammonium and anaerobic ammonium oxidation. In this review we provide an up to date overview of the organisms, genes and enzymes involved in nitrate respiration. We also address the molecular detection of these processes in nature. We show that despite rapid progress in the experimental and genomic analyses of pure cultures, knowledge on the mechanism of nitrate reduction in natural ecosystems is still largely lacking.     

Bacterial Ghosts as antigen and drug delivery system for ocular surface diseases: Effective internalization of Bacterial Ghosts by human conjunctival epithelial cells

The purpose of the presented investigation was to examine the efficiency of the novel carrier system Bacterial Ghosts (BGs), which are empty bacterial cell envelopes of Gram-negative bacteria to target human conjunctival epithelial cells, as well as to test the endocytic capacity of conjunctival cells after co-incubation with BGs generated from different bacterial species, and to foreclose potential cytotoxic effects caused by BGs. The efficiency of conjunctival cells to internalize BGs was investigated using the Chang conjunctival epithelial cell line and primary human conjunctiva-derived epithelial cells (HCDECs) as in vitro model. A high capacity of HCDECs to functionally internalize BGs was detected with the level of internalization depending on the type of species used for BGs generation. Detailed analysis showed no cytotoxic effect of BGs on HCDECs independently of the used bacterial species. Moreover, co-incubation with BGs did not enhance expression of both MHC class I and class II molecules by HCDECs, but increased expression of ICAM-1. The high rates of BG's internalization by HCDECs with no BG-mediated cytotoxic impact designate this carrier system to be a promising candidate for an ocular surface drug delivery system. BGs could be useful for future therapeutic ocular surface applications and eye-specific disease vaccine development including DNA transfer.     

Mutations affecting retina development in Medaka

In a large scale mutagenesis screen of Medaka we identified 60 recessive zygotic mutations that affect retina development. Based on the onset and type of phenotypic abnormalities, the mutants were grouped into five categories: the first includes 11 mutants that are affected in neural plate and optic vesicle formation. The second group comprises 15 mutants that are impaired in optic vesicle growth. The third group includes 18 mutants that are affected in optic cup development. The fourth group contains 13 mutants with defects in retinal differentiation. 12 of these have smaller eyes, whereas one mutation results in enlarged eyes. The fifth group consists of three mutants with defects in retinal pigmentation. The collection of mutants will be used to address the molecular genetic mechanisms underlying vertebrate eye formation.