QUANTITATION OF PHOTOSYSTEM II ACTIVITY IN SPINACH CHLOROPLASTS. EFFECT OF ARTIFICIAL QUINONE ACCEPTORS

Quantitation of photosystem II (PSII) activity in spinach chloroplasts is presented. Rates of PSII electron-transport were estimated from the concentration of PSII reaction-centers (Chl/PSII = 380:1 when measured spectrophotometrically in the ultraviolet [ΔA₃₂₀] and green [ΔA_540–550] regions of the spectrum) and from the rate of light utilization by PSII under limiting excitation conditions. Rates of PSII electron-transport were measured under the same light-limiting conditions using 2,5-dimethylbenzoquinone or 2,5-dichlorobenzoquinone as the PSII artificial electron acceptors. Evaluation is presented on the limitations imposed in the measurement of PSII electron flow to artificial quinones in chloroplasts. Limitations include the static quenching of excitation energy in the pigment bed by added quinones, the fraction of PSII centers (PSII_β) with low affinity to native and added quinones, and the loss of reducing equivalents to molecular oxygen. Such artifacts lowered the yield of steady-state electron transport in isolated chloroplasts and caused underestimation of PSII electron-transport capacity. The limitations described could explain the low PSII concentration estimates in higher plant chloroplasts (Chl/PSII = 600 ± 50) resulting from proton flash yield and/or oxygen flash-yield measurements. It is implied that quantitation of PSII by repetitive flash-yield methods requires assessment of the slow turnover of electrons by PSII_β and, in the presence of added quinones, assessment of the PSII quantum yield.     

Separation of oligonucleotides and DNA fragments by capillary electrophoresis in dynamically and permanently coated capillaries,using a copolymer of acrylamide and β-D-glucopyranoside as a new low viscosity matrix with high sieving capacity

New copolymers of acrylamide and β-D -glucopyranoside were synthesized and characterized. The different reactivity of the two monomers towards radical polymerization meant we could control the growth of the polymer chains whose length was inversely related to the number of glucose residues incorporated in the copolymers. The properties of these polymers were investigated in the separation of oligonucleotides and double-stranded DNA by capillary electrophoresis (CE) in coated and uncoated capillaries. The new copolymers were a suitable matrix for CE due to their high-resolving capacity and low viscosity. We also looked into the advantages of a new method of dynamic suppression of electroosmotic flow based on the addition of small amounts (0.03–0.05%) of dimethylacrylamide to the sieving and to the running buffer. A complete test was run on the reproducibility and efficiency of separations carried out in a permanently and dynamically coated capillary, and the advantages and disadvantages of the two methods were compared.     

Differences in Salivary Proteins as a Function of PROP Taster Status and Gender in Normal Weight and Obese Subjects

Taste plays an important role in processes such as food choices, nutrition status and health. Salivary proteins contribute to taste sensitivity. Taste reduction has been associated with obesity. Gender influences the obesity predisposition and the genetic ability to perceive the bitterness of 6-n-propylthiouracil (PROP), oral marker for food preferences and consumption. We investigated variations in the profile of salivary proteome, analyzed by HPLC-ESI-MS, between sixty-one normal weight subjects (NW) and fifty-seven subjects with obesity (OB), based on gender and PROP sensitivity. Results showed variations of taste-related salivary proteins between NW and OB, which were differently associated with gender and PROP sensitivity. High levels of Ps-1, II-2 and IB-1 proteins belonging to basic proline rich proteins (bPRPs) and PRP-1 protein belonging to acid proline rich proteins (aPRPs) were found in OB males, who showed a lower body mass index (BMI) than OB females. High levels of Ps-1 protein and Cystatin SN (Cyst SN) were found in OB non-tasters, who had lower BMI than OB super-tasters. These new insights on the role of salivary proteins as a factor driving the specific weight gain of OB females and super-tasters, suggest the use of specific proteins as a strategic tool modifying taste responses related to eating behavior.     

Determination of Tetracyclines in Milk,Eggs and Honey Using in-situ Ionic Liquid Based Dispersive Liquid–Liquid Microextraction

In this study, in-situ ionic liquid based dispersive liquid?liquid microextraction method for enrichment of tetracyclines before liquid chromatographic analysis has been improved. A 1-benzyl-3- methylimidazolium chloride was used as an ionic liquid. To increase extraction efficiency, some optimization parameters (amount of ammonium hexafluorophoshate, extraction time, centrifugation time, ratio of ionic liquid/salt) were investigated. At optimized conditions, enrichment factors of four tetracycline antibiotics (tetracycline, chlortetracycline, methacycline, doxycycline) were between 25 and 98. The residues of tetracyclines were not found in the studied real samples. For the accuracy of the method, the concentration of 50 and 250 μg/L of standard tetracycline mixture solutions were spiked to the blank real milk, honey and egg samples and the percentage recoveries were obtained in the range of 75.8–109.7%.     

The Diversity of a Polyclonal FluCell-SELEX Library Outperforms Individual Aptamers as Emerging Diagnostic Tools for the Identification of Carbapenem Resistant Pseudomonas aeruginosa

Textbook procedures require the use of individual aptamers enriched in SELEX libraries which are subsequently chemically synthesized after their biochemical characterization. Here we show that this reduction of the available sequence space of large libraries and thus the diversity of binding molecules reduces the labelling efficiency and fidelity of selected single aptamers towards different strains of the human pathogen Pseudomonas aeruginosa compared to a polyclonal aptamer library enriched by a whole-cell-SELEX involving fluorescent aptamers. The library outperformed single aptamers in reliable and specific targeting of different clinically relevant strains, allowed to inhibit virulence associated cellular functions and identification of bound cell surface targets by aptamer based affinity purification and mass spectrometry. The stunning ease of this FluCell-SELEX and the convincing performance of the P. aeruginosa specific library may pave the way towards generally new and efficient diagnostic techniques based on polyclonal aptamer libraries not only in clinical microbiology.     

Polysialylated-neural cell adhesion molecule (PSA-NCAM) in the human trigeminal ganglion and brainstem at prenatal and adult ages

Background  

The polysialylated neuronal cell adhesion molecule (PSA-NCAM) is considered a marker of developing and migrating neurons and of synaptogenesis in the immature vertebrate nervous system. However, it persists in the mature normal brain in some regions which retain a capability for morphofunctional reorganization throughout life. With the aim of providing information relevant to the potential for dynamic changes of specific neuronal populations in man, this study analyses the immunohistochemical occurrence of PSA-NCAM in the human trigeminal ganglion (TG) and brainstem neuronal populations at prenatal and adult age.     

Møller Energy-Momentum Distribution of Higher Dimensional Vaidya Space-Time

In this paper, we intend to clarify the energy-momentum problem of higher dimensional Vaidya space-time in the general theory of relativity. In this connection, Møller energy and momentum for the higher dimensional Vaidya space-time are evaluated in the frame of general relativity. We have obtained that the Møller energy distribution of higher dimensional Vaidya space-time is equal to zero, while the Møller momentum distribution of higher dimensional Vaidya space-time is not equal to zero.     

On approximations of the de Rham complex and their cohomology

For a commutative algebra R, its de Rham cohomology is an important invariant of R. In the paper, an infinite chain of de Rham-like complexes is introduced where the first member of the chain is the de Rham complex. The complexes are called approximations of the de Rham complex. Their cohomologies are found for polynomial rings and algebras of power series over a field of characteristic zero.