Primary structure of the hemoglobin α-chain of rose-ringed parakeet (Psittacula krameri)

The structure of the hernoglobin α-chain of Rose-ringed Parakeet was determined by sequence degradations of the intact subunit, the CNBr fragments, and peptides obtained by digestion with staphylococcal Glu-specific protease and trypsin. Using this analysis, the complete α-chain structure of 21 avian species is known, permitting comparisons of the protein structure and of avian relationships. The structure exhibits differences from previously established avian α-chains at a total of 61 positions, five of which have residues unique to those of the parakeet (Ser-12, Gly-65, Ser-67, Ala-121, and Leu-134). The analysis defines hemoglobin variation within an additional avian order (Psittaciformes), demonstrates distant patterns for evaluation of relationships within other avian orders, and lends support to taxonomic conclusions from molecular data.     

Calcium channels that are required for secretion from intact nerve terminals of vertebrates are sensitive to omega-conotoxin and relatively insensitive to dihydropyridines. Optical studies with and without voltage-sensitive dyes

Extrinsic absorption changes exhibited by potentiometric dyes have established the ionic basis of the action potential in synchronously activated populations of nerve terminals in the intact neurohypophyses of amphibia and mammals (Salzberg et al., 1983; Obaid et al., 1983, 1985b). Also, large and rapid changes in light scattering, measured as transparency, have been shown to follow membrane depolarization and to be intimately associated with the release of neuropeptides from the nerve terminals of the mouse neurohypophysis (Salzberg et al., 1985; Gainer et al., 1986). We report some experiments that help to define the pharmacological profile of the calcium channels present in intact neurosecretory terminals of vertebrates. For these, we used the peptide toxin omega-conotoxin GVIA (1-5 microM) and the dihydropyridine compounds Bay-K 8644 and nifedipine (2-5 microM), together with the after-hyperpolarization of the nerve terminal action potential. This undershoot depends upon the activation of a calcium-mediated potassium channel, as suggested by its sensitivity to [Ca++]o and charybdotoxin. omega-conotoxin GVIA substantially reduced the after-hyperpolarization in neurosecretory terminals of Xenopus, while neither of the dihydropyridine compounds had any effect under conditions that mimic natural stimulation. The effects of these calcium channel modifiers on the action potential recorded optically from the terminals of the Xenopus neurohypophysis were faithfully reflected in the behavior of the light-scattering changes observed in the neurohypophysis of the CD-1 mouse. omega-conotoxin GVIA (5 microM) reduced the size of the intrinsic optical signal associated with secretion by 50%, while the dihydropyridines had little effect. These observations suggest that the type of calcium channel that dominates the secretory behavior of intact vertebrate nerve terminals is at least partially blocked by omega-conotoxin GVIA and is insensitive, under normal conditions, to dihydropyridines.     

A small camel-milk protein rich in cysteine/half-cystine

A small protein (M_r about 14 000) rich in cysteine/half-cystine has been isolated from camel milk by exclusion chromatography and reverse-phase high-performance liquid chromatography. The N-terminal amino acid sequence shows a region with several positional identities with and -caseins, which however lack cysteine residues; postions 16–20 are identical and involve the serine residues that have been found to be phosphorylated in -caseins.     

Bicarbonate-Chloride Exchange in Erythrocyte Suspensions: Stopped-Flow pH Electrode Measurements

A pH-sensitive glass electrode was used in a temperature-controlled stopped-flow rapid reaction apparatus to determine rates of pH equilibration in red cell suspensions. The apparatus requires less than 2 ml of reactants. The electrode is insensitive to pressure and flow variations, and has a response time of < 5 ms. A 20% suspension of washed fresh human erythrocytes in saline at pH 7.7 containing NaHCO₃ and extracellular carbonic anhydrase is mixed with an equal volume of 30 mM phosphate buffer at pH 6.7. Within a few milliseconds after mixing, extracellular HCO₃^- reacts with H⁺ to form CO₂, which enters the red cells and rehydrates to form HCO₃^-, producing an electrochemical potential gradient for HCO₃^- from inside to outside the cells. HCO₃^- then leaves the cells in exchange for Cl^-, and extracellular pH increases as the HCO₃^- flowing out of the cells reacts with H⁺. Flux of HCO₃^- is calculated from the dpH/dt during HCO₃^--Cl^- exchange, and a velocity constant is computed from the flux and the calculated intracellular and extracellular [HCO₃^-]. The activation energy for the exchange process is 18.6 kcal/mol between 5°C and 17°C (transition temperature), and 11.4 kcal/mol from 17°C to 40°C. The activation energies and transition temperature are not significantly altered in the presence of a potent anion exchange inhibitor (SITS), although the fluxes are markedly decreased. These findings suggest that the rate-limiting step in red cell anion exchange changes at 17°C, either because of an alteration in the nature of the transport site or because of a transition in the physical state of membrane lipids affecting protein-lipid interactions.     

Genetic diversity among different species of the genus Leiurus (Scorpiones: Buthidae) in Saudi Arabia and the Middle East

The molecular phylogenetic relationship among two species of genus Leiurus, from Saudi Arabia with additional comparative sequence data available from Egypt, Oman and Turkey is presented. The molecular phylogeny was performed using maximum parsimony, neighbor joining and bayesian inference. Our results indicate a clear deep splitting between the Western clade, which represented by L. quinuestriatus sequences from Egypt and those from the Eastern clade which encompassing different Leiurus species from Saudi Arabia, Oman and Turkey was shown. Also, the phylogenetic relationship represents additional support for the taxonomic status of Arabian Leiurus species.     

Mn3O4 nanoparticles: Synthesis,characterization and their antimicrobial and anticancer activity against A549 and MCF-7 cell lines

Due to their inexpensive and eco-friendly nature, and existence of manganese in various oxidation states and their natural abundance have attained significant attention for the formation of Mn₃O₄ nanoparticles (Mn₃O₄ NPs). Herein, we report the preparation of Mn₃O₄ nanoparticles using manganese nitrate as a precursor material by utilization of a precipitation technique. The as-prepared Mn₃O₄ nanoparticles (Mn₃O₄ NPs) were characterized by using X-ray powder diffraction (XRD), UV–Visible spectroscopy (UV–Vis), High-Resolution Transmission electron microscopy (HRTEM), Field emission scanning electron microscopy (FESEM), Thermal gravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FT-IR). The antimicrobial properties of the as-synthesized Mn₃O₄ nanoparticles were investigated against numerous bacterial and fungal strains including S. aureus, E. coli, B. subtilis, P. aeruginosa, A. flavus and C. albicans. The Mn₃O₄ NPs inhibited the growth of S. aureus with a minimum inhibitory concentration (MIC) of 40 μg/ml and C. albicans with a MIC of 15 μg/ml. Furthermore, the Mn₃O₄ NPs anti-cancer activity was examined using MTT essay against A549 lung and MCF-7 breast cancer cell lines. The Mn₃O₄ NPs revealed significant activity against the examined cancer cell lines A549 and MCF-7. The IC₅₀ values of Mn₃O₄ NPs with A549 cell line was found at concentration of 98 µg/mL and MCF-7 cell line was found at concentration of 25 µg/mL.     

Cleavage Specificities of Individual Members of Kallikrein Family of Proteins on Synthetic Peptide Containing the Bradykinin Sequence

We have analyzed the effect on bond specificity of various isolated members of the mouse kallikrein family of proteins on a synthetic peptide containing the bradykinin sequence. The cleavage pattern shows the selected specificity of these proteases toward the synthetic peptide. The Phe–His bond (positions 11–12) in the synthetic peptide was favorably cleaved by most of the members in this family, including gamma nerve growth factor. On the other hand, the Lys–Arg bond (position 3–4) was found to be susceptible only to -NGF. The combination of these cleavages could result in the degradation of bradykinin in vivo.     

Imatinib potentiates antitumor T cell responses in gastrointestinal stromal tumor through the inhibition of Ido

Imatinib mesylate targets mutated KIT oncoproteins in gastrointestinal stromal tumor (GIST) and produces a clinical response in 80% of patients. The mechanism is believed to depend predominantly on the inhibition of KIT-driven signals for tumor-cell survival and proliferation. Using a mouse model of spontaneous GIST, we found that the immune system contributes substantially to the antitumor effects of imatinib. Imatinib therapy activated CD8(+) T cells and induced regulatory T cell (T(reg) cell) apoptosis within the tumor by reducing tumor-cell expression of the immunosuppressive enzyme indoleamine 2,3-dioxygenase (Ido). Concurrent immunotherapy augmented the efficacy of imatinib in mouse GIST. In freshly obtained human GIST specimens, the T cell profile correlated with imatinib sensitivity and IDO expression. Thus, T cells are crucial to the antitumor effects of imatinib in GIST, and concomitant immunotherapy may further improve outcomes in human cancers treated with targeted agents.