Study of the equilibrium dynamics of cell protein structure using the tryptophan fluorescence method at room temperature

Room-temperature tryptophane phosphorescence (RTTP) of liver tissue cells has been studied. It is shown that over a millisecond range RTTP is absent in soluble proteins of the cytoplasm, karyoplasm, mitochondrial matrix, and the phosphorescent signal is controlled only by proteins of the subcellular structures incorporated into the membranes. It is concluded that, unlike the membrane proteins, the cytoplasm and organelle matrix-soluble proteins are characterized by a high level of intramolecular equilibrium mobility, which causes RTTP quenching following a dynamic mechanism. In membrane proteins, which fluoresce in a millisecond range the level of equilibrium conformation motions is limited, probably, due to protein-protein and protein-lipid interactions.     

Novel functions of Noggin proteins: inhibition of Activin/Nodal and Wnt signaling

The secreted protein Noggin1 is an embryonic inducer that can sequester TGFβ cytokines of the BMP family with extremely high affinity. Owing to this function, ectopic Noggin1 can induce formation of the headless secondary body axis in Xenopus embryos. Here, we show that Noggin1 and its homolog Noggin2 can also bind, albeit less effectively, to ActivinB, Nodal/Xnrs and XWnt8, inactivation of which, together with BMP, is essential for the head induction. In support of this, we show that both Noggin proteins, if ectopically produced in sufficient concentrations in Xenopus embryo, can induce a secondary head, including the forebrain. During normal development, however, Noggin1 mRNA is translated in the presumptive forebrain with low efficiency, which provides the sufficient protein concentration for only its BMP-antagonizing function. By contrast, Noggin2, which is produced in cells of the anterior margin of the neural plate at a higher concentration, also protects the developing forebrain from inhibition by ActivinB and XWnt8 signaling. Thus, besides revealing of novel functions of Noggin proteins, our findings demonstrate that specification of the forebrain requires isolation of its cells from BMP, Activin/Nodal and Wnt signaling not only during gastrulation but also at post-gastrulation stages.     

Dynamic changes in the copy number of pluripotency and cell proliferation genes in human ESCs and iPSCs during reprogramming and time in culture

Genomic stability is critical for the clinical use of human embryonic and induced pluripotent stem cells. We performed high-resolution SNP (single-nucleotide polymorphism) analysis on 186 pluripotent and 119 nonpluripotent samples. We report a higher frequency of subchromosomal copy number variations in pluripotent samples compared to nonpluripotent samples, with variations enriched in specific genomic regions. The distribution of these variations differed between hESCs and hiPSCs, characterized by large numbers of duplications found in a few hESC samples and moderate numbers of deletions distributed across many hiPSC samples. For hiPSCs, the reprogramming process was associated with deletions of tumor-suppressor genes, whereas time in culture was associated with duplications of oncogenic genes. We also observed duplications that arose during a differentiation protocol. Our results illustrate the dynamic nature of genomic abnormalities in pluripotent stem cells and the need for frequent genomic monitoring to assure phenotypic stability and clinical safety.     

First Record of Fungal Fruit Bodies on a Leaf from Late Eocene Rovno Amber (Ukraine)

Paleontological Journal - The first record of fruit bodies of a microscopic fungus on the leaf of an unidentified dicotyledonous plant in amber is reported. The fungus is represented by numerous...     

Systematic review and meta-analysis: rapid diagnostic tests versus placental histology, microscopy and PCR for malaria in pregnant women

Background

To prepare field sites for malaria vaccine trials, it is important to determine baseline antibody and T cell responses to candidate malaria vaccine antigens. Assessing T cell responses is especially challenging, given genetic restriction, low responses observed in endemic areas, their variability over time, potential suppression by parasitaemia and the intrinsic variability of the assays.

Methods

In Part A of this study, antibody titres were measured in adults from urban and rural communities in Ghana to recombinant Plasmodium falciparum CSP, SSP2/TRAP, LSA1, EXP1, MSP1, MSP3 and EBA175 by ELISA, and to sporozoites and infected erythrocytes by IFA. Positive ELISA responses were determined using two methods. T cell responses to defined CD8 or CD4 T cell epitopes from CSP, SSP2/TRAP, LSA1 and EXP1 were measured by ex vivo IFN-γ ELISpot assays using HLA-matched Class I- and DR-restricted synthetic peptides. In Part B, the reproducibility of the ELISpot assay to CSP and AMA1 was measured by repeating assays of individual samples using peptide pools and low, medium or high stringency criteria for defining positive responses, and by comparing samples collected two weeks apart.

Results

In Part A, positive antibody responses varied widely from 17%-100%, according to the antigen and statistical method, with blood stage antigens showing more frequent and higher magnitude responses. ELISA titres were higher in rural subjects, while IFA titres and the frequencies and magnitudes of ex vivo ELISpot activities were similar in both communities. DR-restricted peptides showed stronger responses than Class I-restricted peptides. In Part B, the most stringent statistical criteria gave the fewest, and the least stringent the most positive responses, with reproducibility slightly higher using the least stringent method when assays were repeated. Results varied significantly between the two-week time-points for many participants.

Conclusions

All participants were positive for at least one malaria protein by ELISA, with results dependent on the criteria for positivity. Likewise, ELISpot responses varied among participants, but were relatively reproducible by the three methods tested, especially the least stringent, when assays were repeated. However, results often differed between samples taken two weeks apart, indicating significant biological variability over short intervals.     

Physicochemical Properties and Specific Structural Features of Protein–Lipid Composites of Increased Nutritive Value

Fractional and component compositions of protein–lipid composites with increased nutritive value (compared to the protein preparations from which they were produced) were studied based on solubility and electrophoretic behavior. Differences in the fractional compositions of proteins and the amounts of hydrogen, ionic, and hydrophobic bonds were found. It was demonstrated that the water-, salt-, and alkali-soluble fractions of proteins changed during the manufacturing of the composites with soybean and wheat bran flour; the water- and alkali-soluble fractions, with protein concentrate from bran. Heterogeneity of the compositions and specific conformational features of composite proteins resulting from disulfide bonds were found. It was demonstrated that, during the manufacturing of composites, proteins of soybean flour aggregated (with the involvement of disulfide bonds), whereas protein products from wheat bran disaggregated. Breaks of interchain (wheat) or intrachain (concentrate) disulphide bonds accompanied the disaggregation. Overall the properties and specific structural features of the protein–lipid composites studied depended on the nature of the protein (soybean or wheat), type of initial preparations (flour or concentrate), and method of their production (emulsifying or drying).