Characterisation of PSE zones in semimembranosus pig muscle

Pig semimembranosus muscles, sampled from normal hams or from PSE-zones of defective hams, were analysed by histochemistry and electrophoretic techniques. PSE zones were characterised by a disorganisation of fibre alignment and a significant increase of inter fibre spacing (26.2% vs. 16.9%, p<0.05). Protein solubility was significantly lower in defective muscle (55.4 vs. 91.5mg/g, p<0.001). SDS-PAGE evidenced in such samples a lower abundance of the 97, 40 and 26kDa bands in the sarcoplasmic fraction and a higher abundance of the 97, 58, 34, 31, 15 and 11kDa bands in the myofibrillar fraction. Intensity of the MHC band (200kDa) was lower in PSE zone samples. By 2-D electrophoresis, it was shown that troponin T, MLC 1 and alpha-crystallin were less proteolysed in defective muscles, while creatine kinase fragments were more represented. One form of HSP 27 was absent from PSE zone samples. Overall, meat from PSE-zones and fast pH fall-PSE meat show numerous histological and biochemical similarities, particularly in their protein characteristics.     

Modelling of simultaneous two-sided migration into water and olive oil from nylon food packaging

Nylon 6 and nylon 12 food packaging materials used as sausage casings are typically exposed to fatty food on one side and boiling water on the other during the cooking process. To simulate the migration behaviour under these conditions, a special migration cell was constructed and filled with olive oil on one side of the polymer and water on the other to find out what amounts of the migrants will transfer to either side and phase at 100 °C. Results show that when a nylon 6 film is exposed to the conditions as described above, total mass transfer of the monomer—caprolactam—into the water phase occurs after 2 h at 100 °C. Nylon 12 sausage casings release similar amounts of their monomer—laurolactam—into both the aqueous and oil phase. An existing computer migration model was adapted to simulate the situation of simultaneous two-sided migration applying previously determined diffusion and partitioning coefficients. The suitability of the model was confirmed by experimental data.     

Distribution of conjugated linoleic acid in total and subcellular fractions from normal and cancerous parts of human testes

The objective of the present study was to examine differences in the fatty acid composition of subcellular fractions from normal and cancerous parts of human testes. The conjugated linoleic acid (CLA) content was significantly higher in total testicular carcinoma (TC), but significantly lower in the mitochondrial fraction of TC in comparison to normal testicular tissue. The subcellular distribution pattern of CLA was similar to that of monounsaturated fatty acids, but different to that of 18:2n-6 (linoleic acid), underlining the different physiological properties of CLA and 18 : 2n-6. Because polyunsaturated fatty acids (PUFAs) have been suggested to have an effect on cancer risk and previous research has found that CLA inhibits the metabolism of 18 : 2n-6 into 20 : 4n-6, the contents of n-6 and n-3 PUFAs were determined. Significant differences were observed for 18 : 2n-6, 18 : 3n-3, 20 : 5n-3, and 22 : 6n-3, with 18 : 2n-6, 18 : 3n-3, and 20 : 5n-3 contents being higher and 22 : 6n-3 content being lower in TC than in normal testicular tissue. These results indicate a changed availability of substrates for the cyclooxygenase (COX) or lipooxygenase (LOX) pathways generating eicosanoids. Although not statistically significant, the reduced content of 20 : 4n-6 shown in this study might be due to an increased metabolism of this fatty acid into eicosanoids.     

Development of an autofluorescent translocation biosensor system to investigate protein-protein interactions in living cells

Protein-protein interactions are crucial for all cellular events. To analyze protein-protein interactions in live mammalian cells, we developed novel protein translocation biosensors composed of glutathione S-transferase, mutants of GFP, and a rational combination of nuclear import and export signals. Nuclear accumulation of the cytoplasmic biosensors served as the reliable indicator, which was induced by the formation of protein complexes and could easily be detected by fluorescence microscopy. The efficacy of the system was systematically investigated by mapping the p53/mdm2 protein interaction interface. Specificity and general applicability of the biosensors were confirmed by studying additional classes of protein interaction domains (IDs), e.g., the leucine zipper IDs of Jun/Fos and the coiled-coil ID of Bcr-Abl in different cell lines. Importantly, we found that, in comparison to protein complementation assays, our system proved highly efficient and reversible and thus suited for the identification of molecular decoys to prevent specific protein-protein interactions in living cells. Reversibility was demonstrated in competition experiments by overexpressing the specific IDs or by the application of a p53/mdm2 protein interaction inhibitor. Thus, besides the convenient mapping of protein IDs in living cells, the modular translocation system has great potential to be employed in numerous cell-based assays for the identification of small-molecule protein interaction inhibitors as potential novel therapeutics.     

Analysis of CheA histidine phosphorylation and its influence on protein stability by high-resolution element and electrospray mass spectrometry

A combination of electrospray mass spectrometry (ESI-MS) and element mass spectrometry (ICPMS) with phosphorus detection was used to characterize histidine phosphorylation (His-48) of the chemotaxis protein CheA quantitatively. The phosphorylation at His-48 was found to be responsible for a stabilization of the protein. For this investigation, the acceptor domain and the kinase domain of the bacterial chemotaxis protein CheA were recombinantly expressed as single proteins. Using in vitro kinase assay conditions, the acceptor domain CheA-H was phosphorylated by the kinase domain CheA-C. The degree of histidine phosphorylation was determined by nanoelectrospray mass spectrometry of intact CheA-H, and was found to be limited to a maximum value of approximately 50%. The site specificity of CheA-H phosphorylation was controlled by nanoESI-MS/MS of the [M + 16H](16+) ion of intact (pHis)-CheA-H and allowed localization of the pHis residue to the region between residues 32 and 86, containing candidates His-48 and His-67, for which His-48 phosphorylation has been described. Analysis of the tryptic digest of in vitro histidine-phosphorylated CheA-H by capillary chromatography coupled to ESI-MS and to ICPMS with phosphorus detection revealed a truncated (pHis)-CheA-H protein as the only phosphorus-containing analyte. Since the truncated (pHis)-CheA-H in the digest was found to exhibit a higher degree of phosphorylation than could be generated by in vitro phosphorylation without trypsin treatment, it is concluded that histidine phosphorylation at His-48 strongly interferes with structural properties of the CheA-H domain in particular with respect to proteolytic degradation by trypsin.     

The mechanism for enhanced autoadhesion in azoester-modified polybutadienes

The addition of IAD pendant groups to PB molecules results in a larger effective chain crosssectional area with consequent decrease in chain entanglements. This causes the rubber to be more complaint at low strains and strain rates. Simultaneously, the IAD structures give rise to polar and H-bond interactions which cause the material to exhibit strong adhesion and to possess high green strength. As a result, the IAD-PB is a relatively rare example of a synthetic polymer with good autoadhesive properties.     

Differences in information sent to minority and nonminority prospective applicants to clinical, counseling, and school psychology programs.

Investigated whether doctoral-level professional psychology programs responded differently to initial requests for information from minority and nonminority applicants. A letter from a fictitious student was sent to 257 programs. Programs were randomly assigned to an ethnic condition (White, Black, or Hispanic). The minority students were more likely to receive a response than were nonminority students, and minority students received more personal forms of communication than did the nonminority student. However, the overall amount of minority recruitment information shared with applicants was the same for both minority and nonminority students. The findings suggest that few programs are using materials sent to prospective minority applicants as a method for implementing their affirmative action policy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An Ultrafast Laser Scanner Microscope for Digital Image Analysis

The design of an ultrafast laser scanner microscope has been completed and an experimental model has been constructed. The instrument is described and the considerations that led to our choice of scanning method and optical and electronic system design are discussed. The scanner incorporates numerous new technologic features, and promises to make high-resolution cell analysis practical at data rates comparable to those obtained now only in flow cytometry.