Identification of proteins involved in inhibition of spheroid formation under microgravity

Many types of cells transit in vitro from a two‐ to a three‐dimensional growth, when they are exposed to microgravity. The underlying mechanisms are not yet understood. Hence, we investigated the impact of microgravity on protein content and growth behavior. For this purpose, the human thyroid cancer cells FTC‐133 were seeded either in recently developed cell containers that can endure enhanced physical forces and perform media changes and cell harvesting automatically or in T‐25 culture flasks. All cells were cultured for five days at 1g. Afterwards, a part of the cell containers were flown to the International Space Station, while another part was kept on the ground. T‐25 flasks were mounted on and next to a Random Positioning Machine. The cells were cultured for 12 days under the various conditions, before they were fixed with RNAlater. All fixed cultures showed monolayers, but three‐dimensional aggregates were not detected. In a subsequent protein analysis, 180 proteins were identified by mass spectrometry. These proteins did not indicate significant differences between cells exposed to microgravity and their 1g controls. However, they suggest that an enhanced production of proteins related to the extracellular matrix could detain the cells from spheroid formation, while profilin‐1 is phosphorylated.     

Loss of the PLA2G2A gene in a sporadic colorectal tumor of a patient with a PLA2G2A germline mutation and absence of PLA2G2A germline alterations in patients with FAP

The Min (multiple intestinal neoplasia) mouse with a germline mutation in the adenomatous polyposis coli gene serves as an animal model for familial adenomatous polyposis coli (FAP). The number and age at onset of colorectal adenomas varies in the offspring of Min mice crossed with other strains. The murine gene for the secretory phospholipase A2 (PLA2G2A) was found to be the main candidate for these variations. To test the hypothesis of a correlation between PLA2G2A gene alterations and human tumor development, we screened 14 patients with FAP and 20 patients with sporadic colorectal cancer for germline and somatic PLA2G2A gene mutations. None of the individuals with FAP showed PLA2G2A germline alterations. However, a germline mutation was observed in one patient with an apparently sporadic colorectal tumor; the wildtype allele was somatically lost in the tumor of this patient. Received: 12 February 1997 / Accepted: 9 May 1997     

N-3 but not N-6 fatty acids reduce the expression of the combined adhesion and scavenger receptor CD36 in human monocytic cells

CD36, a multifunctional adhesion receptor e.g. for thrombospondin and collagen, as well as a scavenger receptor for oxidized low density lipoprotein, is expressed e.g. on platelets and monocytes. By this dual role it might be involved in early steps of atherosclerosis like the recruitment of monocytes and formation of foam cells. We therefore studied the effects of n-3 fatty acids on CD36 expression in human monocytic cells. Incorporation of eicosapentaenoic acid (EPA, C20:5n-3) and docosahexaenoic acid (DHA, C22:6n-3) into cellular phospholipids resulted in a significant reduction of CD36 expression at the mRNA and protein level, whereas arachidonic acid (AA, C20: 4n-6) and linoleic acid (LA, C18:2n-6) tended to increase CD36 expression compared to the control. This specific down-regulation of CD36 by n-3 fatty acids in cells involved in the initiation and progression of atherogenesis and inflammation, represents a further mechanism that may contribute to the beneficial effects of n-3 polyunsaturated fatty acids (PUFA) in these disorders.     

The thymus microenvironment in regulating thymocyte differentiation

The thymus plays a crucial role in the development of T lymphocytes by providing an inductive microenvironment in which committed progenitors undergo proliferation, T-cell receptor gene rearrangements and thymocyte differentiate into mature T cells. The thymus microenvironment forms a complex network of interaction that comprises non lymphoid cells (e.g., thymic epithelial cells, TEC), cytokines, chemokines, extracellular matrix elements (ECM), matrix metalloproteinases and other soluble proteins. The thymic epithelial meshwork is the major component of the thymic microenvironment, both morphologically and phenotypically limiting heterogeneous regions in thymic lobules and fulfilling an important role during specific stages of T-cell maturation. The process starts when bone marrow-derived lymphocyte precursors arrive at the outer cortical region of the thymic gland and begin to mature into functional T lymphocytes that will finally exit the thymus and populate the peripheral lymphoid organs. During their journey inside the thymus, thymocytes must interact with stromal cells (and their soluble products) and extracellular matrix proteins to receive appropriate signals for survival, proliferation and differentiation. The crucial components of the thymus microenvironment, and their complex interactions during the T-cell maturation process are summarized here with the objective of contributing to a better understanding of the function of the thymus, as well as assisting in the search for new therapeutic approaches to improve the immune response in various pathological conditions.Key words: thymus, T-cell maturation, thymic microenvironment, thymocyte differantiation, chemokines, extracellular matrix, thymic nurse cells, metalloproteinases     

Effects of retinoic acid on the muscle patterns produced during forelimb regeneration in larval salamanders (Ambystoma)

After systemic treatment with retinoic acid (RA), Ambystoma opacum and A. punctatum larvae regenerated forelimbs with a wide variety of skeletal and gross anatomical abnormalities. Yet the musculatures within the RA-treated limb regenerates were normal even in instances where the cartilages were deformed beyond recognition as components of the limb skeleton. RA is known to induce reduplication of limb structures, sometimes entire segments. When the latter condition occurred in the present study, the corresponding replicates exhibited limb musculatures which were perfect down to minute details, yet of opposite bilateral symmetry. The results attest, firstly, to the independence of myogenesis and chondrogenesis during limb regeneration. Secondly, RA treatment unmasked an otherwise hidden potential within postembryonic salamander limb tissue for the morphogenesis of the contralateral musculature.     

Notiz über eine Modifikation der Weberschen Tüpfelreaktionsmethode zum Nachweis von Vitamin C in Pflanzen

Zusammenfassung Das Tüpfelreaktionsverfahren mit Dichlorphenol-Indophenol-Gelatinefolie eignet sich wegen seiner Einfachheit bezüglich Herstellung der Unterlage und Anwendung besonders als Freilandmethode zur Auffindung von Vitamin C-reichen Pflanzen.     

Characterization of the human primary visual cortex and cerebellum proteomes using shotgun mass spectrometry-data-independent analyses

We present the first characterization of the human occipital lobe (primary visual cortex) and cerebellum proteomes. Proteins were identified using a combination of gel electrophoresis and data‐independent nanoflow liquid chromatography mass spectrometry (nLC‐MS^E). The resulting data sets comprised 391 and 330 unique proteins in occipital lobe and cerebellum, respectively, present in at least 75% of the analyzed samples with 297 proteins found in common. These proteins have been associated previously with conditions, such as neurological disorder, progressive motor neuropathy, Parkinson's disease and schizophrenia. The unique proteins identified in the occipital lobe included the interesting finding of growth hormone and several members of the Ca²⁺‐dependent calmodulin kinase and serine/threonine protein phosphatase families. The complete mapping of these and other brain proteomes may help in the elucidation of neurological processes and identify potential targets for therapeutic strategies.