Membrane-enriched proteome changes and prion protein expression during neural differentiation and in neuroblastoma cells.

BACKGROUND: The function of the prion protein, involved in the so-called prion diseases, remains a subject of intense debate and the possibility that it works as a pleiotropic protein through the interaction with multiple membrane proteins is somehow supported by recent reports. Therefore, the use of proteomic and bioinformatics combined to uncover cellular processes occurring together with changes in the expression of the prion protein may provide further insight into the putative pleiotropic role of the prion protein. RESULTS: This study assessed the membrane-enriched proteome changes accompanying alterations in the expression of the prion protein. A 2D-DIGE approach was applied to two cell lines after prefractionation towards the membrane protein subset: an embryonic stem cell line and the PK1 subline of neuroblastoma cells which efficiently propagates prion infection. Several proteins were differentially abundant with the increased expression of the prion protein during neural differentiation of embryonic stem cells and with the knockdown of the prion protein in PK1 cells. The identity of around 20% of the differentially abundant proteins was obtained by tandem MS. The catalytic subunit A of succinate dehydrogenase, a key enzyme for the aerobic energy metabolism and redox homeostasis, showed a similar abundance trend as the prion protein in both proteomic experiments. A gene ontology analysis revealed "myelin sheath", "organelle membrane" and "focal adhesion" associated proteins as the main cellular components, and "protein folding" and "ATPase activity" as the biological processes enriched in the first set of differentially abundant proteins. The known interactome of these differentially abundant proteins was customized to reveal four interactors with the prion protein, including two heat shock proteins and a protein disulfide isomerase. CONCLUSIONS: Overall, our study shows that expression of the prion protein occurs concomitantly with changes in chaperone activity and cell-redox homeostasis, emphasizing the functional link between these cellular processes and the prion protein.

Identification of Sc-type ILV6 as a target to reduce diacetyl formation in lager brewers' yeast.

Diacetyl causes an unwanted buttery off-flavor in lager beer. It is spontaneously generated from α-acetolactate, an intermediate of yeast's valine biosynthesis released during the main beer fermentation. Green lager beer has to undergo a maturation process lasting two to three weeks in order to reduce the diacetyl level below its taste-threshold. Therefore, a reduction of yeast's α-acetolactate/diacetyl formation without negatively affecting other brewing relevant traits has been a long-term demand of brewing industry. Previous attempts to reduce diacetyl production by either traditional approaches or rational genetic engineering had different shortcomings. Here, three lager yeast strains with marked differences in diacetyl production were studied with regard to gene copy numbers as well as mRNA abundances under conditions relevant to industrial brewing. Evaluation of data for the genes directly involved in the valine biosynthetic pathway revealed a low expression level of Sc-ILV6 as a potential molecular determinant for low diacetyl formation. This hypothesis was verified by disrupting the two copies of Sc-ILV6 in a commercially used lager brewers' yeast strain, which resulted in 65% reduction of diacetyl concentration in green beer. The Sc-ILV6 deletions did not have any perceptible impact on beer taste. To our knowledge, this has been the first study exploiting natural diversity of lager brewers' yeast strains for strain optimization.

[Results of mycologic studies of donated breast milk]. / Ergebnisse mykologischer Untersuchungen gespendeter Frauenmilch.

From 1968 to 1989 altogether 37,000 specimens of donated and collected mother's milk were mycologically examined by means of a liquid medium (twofold concentrated Raulin solution). The yearly incidence of Candida albicans varied between 8.5 and 5.2%. 25% respectively 14.8% of the donors (n = 60 respectively 813) had delivered milk to the human milk bank which was contaminated by Candida albicans. The mother's milk was primarily contaminated by the donor's own suckling baby. 92.3% of these infants were infected with Candida albicans in the mouth and/or rectum and/or on the skin. Candida albicans was also detected in 46.2% on the nipples of the mothers. It is recommended to transport donated mother's milk at temperatures of 4-8 degrees C and to store the milk at -20 degrees C until the mycological examination is finished to exclude samples contaminated by Candida albicans. Judging our experience donated human milk to be fed in raw state should be regularly controlled mycologically. If the donated milk contains Candida albicans, the donation of milk should be interrupted and an antifungal treatment of the donor and her baby should be performed.

[Endophlebitis hepatica obliterans. Unusual cause of liver insufficiency in early childhood in a dizygotic twin]. / Endophlebitis hepatica obliterans. Ungewöhnliche Ursache einer Leberinsuffizienz im frühen Kindesalter bei einem zweieiigen Zwilling.

Findings recorded from obliterative hepatic endophlebitis are described in this paper and are compared with international literature. They had been obtained from a male twin who had died with clinical symptoms of hepatic failure. Differential diagnosis of liver insufficiency in early childhood is discussed in some detail. Also recorded was obliterative angiitis of intramural blood vessels in the ileum. Systemic vasculitis is postulated, possibly developed on the basis of an immunological reaction. Intra-uterine infection had probably been the most likely cause.