Phosphate accelerates displacement of Fe(III) by Fe(II) in the ferroxidase center of Pyrococcus furiosus ferritin

The iron-storage protein, ferritin, is widely found in all Domains of life. A conserved diiron center in ferritin catalyzes oxidation of Fe(II) and regulates storage of the resultant Fe(III) oxidation product. When this center is filled with Fe(III), in bacterial or archaeal ferritin the presence of phosphate accelerates the rate of Fe(II) oxidation. The molecular mechanism underlying this stimulatory effect of phosphate is unknown. Using site directed mutagenesis of the residues in the diiron center of the archaeal ferritin from Pyrococcus furiosus we show that phosphate facilitates displacement of Fe(III) by Fe(II) from this site. Therefore, the rate of Fe(II) oxidation increases only when the ferroxidase center is filled with Fe(III).     

The Effects of a Prophylactic Knee Brace and Two Neoprene Knee Sleeves on the Performance of Healthy Athletes: A Crossover Randomized Controlled Trial

Knee injury is one of the major problems in sports medicine, and the use of prophylactic knee braces is an attempt to reduce the occurrence and/or severity of injuries to the knee joint ligament(s) without inhibiting knee mobility. The aim of the present study was to examine the effect of one recently designed prophylactic knee brace and two neoprene knee sleeves upon performance of healthy athletes. Thirty-one healthy male athletes (age = 21.2±1.5) volunteered as participants to examine the effect of prophylactic knee brace/sleeves on performance using isokinetic and functional tests. All subjects were tested in four conditions in a random order: 1. nonbraced (control) 2. using a neoprene knee sleeve 3. using a knee sleeve with four bilateral metal supports and 4. using a prophylactic knee brace. The study design was a crossover, randomized, controlled trial. Subjects completed single leg vertical jump, cross-over hop, and the isokinetic knee flexion and extension (at 60, 180, 300°/sec). Data were collected from the above tests and analyzed for jump height, cross-over hop distance, peak torque to body weight ratio and average power, respectively. Comparisons of these variables in the four testing conditions revealed no statistically significant difference (p>0.05). The selected prophylactic brace/sleeves did not significantly inhibit athletic performance which might verify that their structure and design have caused no complication in the normal function of the knee joint. Moreover, it could be speculated that, if the brace or the sleeves had any limiting effect, our young healthy athletic subjects were well able to generate a mean peak torque large enough to overcome this possible restriction. Further studies are suggested to investigate the long term effect of these prophylactic knee brace and sleeves as well as their possible effect on the adjacent joints to the knee.     

Fatty acid-binding protein 4 (FABP4) and FABP5 modulate cytokine production in the mouse thymic epithelial cells

Thymic stromal cells, including cortical thymic epithelial cells (cTEC) produce many humoral factors, such as cytokines and eicosanoids to modulate thymocyte homeostasis, thereby regulating the peripheral immune responses. In this study, we identified fatty acid-binding protein (FABP4), an intracellular fatty acid chaperone, in the mouse thymus, and examined its role in the control of cytokine production in comparison with FABP5. By immunofluorescent staining, FABP4(+) cells enclosing the thymocytes were scattered throughout the thymic cortex with a spatial difference from the FABP5(+) cell that were distributed widely throughout the cTEC. The FABP4(+) cells were immunopositive for MHC class II, NLDC145 and cytokeratin 8, and were identified as part of cTEC. The FABP4(+) cells were identified as thymic nurse cells (TNC), a subpopulation of cTEC, by their active phagocytosis of apoptotic thymocytes. Furthermore, FABP4 expression was confirmed in the isolated TNC at the gene and protein levels. To explore the function of FABP in TNC, TSt-4/DLL1 cells stably expressing either FABP4 or FABP5 were established and the gene expressions of various cytokines were examined. The gene expression of interleukin (IL)-7 and IL-18 was increased both in FABP4 and FABP5 over-expressing cells compared with controls, and moreover, the increase in their expressions by adding of stearic acids was significantly enhanced in the FABP4 over-expressing cells. These data suggest that both FABPs are involved in the maintenance of T lymphocyte homeostasis through the modulation of cytokine production, which is possibly regulated by cellular fatty acid-mediated signaling in TEC, including TNC.     

A Synthetic Peptide with the Putative Iron Binding Motif of Amyloid Precursor Protein (APP) Does Not Catalytically Oxidize Iron

The β-amyloid precursor protein (APP), which is a key player in Alzheimer's disease, was recently reported to possess an Fe(II) binding site within its E2 domain which exhibits ferroxidase activity [Duce et al. 2010, Cell 142: 857]. The putative ligands of this site were compared to those in the ferroxidase site of ferritin. The activity was indirectly measured using transferrin, which scavenges the Fe(III) product of the reaction. A 22-residue synthetic peptide, named FD1, with the putative ferroxidase site of APP, and the E2 domain of APP were each reported to exhibit 40% of the ferroxidase activity of APP and of ceruloplasmin. It was also claimed that the ferroxidase activity of APP is inhibited by Zn(II) just as in ferritin. We measured the ferroxidase activity indirectly (i) by the incorporation of the Fe(III) product of the ferroxidase reaction into transferrin and directly (ii) by monitoring consumption of the substrate molecular oxygen. The results with the FD1 peptide were compared to the established ferroxidase activities of human H-chain ferritin and of ceruloplasmin. For FD1 we observed no activity above the background of non-enzymatic Fe(II) oxidation by molecular oxygen. Zn(II) binds to transferrin and diminishes its Fe(III) incorporation capacity and rate but it does not specifically bind to a putative ferroxidase site of FD1. Based on these results, and on comparison of the putative ligands of the ferroxidase site of APP with those of ferritin, we conclude that the previously reported results for ferroxidase activity of FD1 and - by implication - of APP should be re-evaluated.     

Effects of 6(5H)-phenanthridinone,an Inhibitor of Poly(ADP-ribose)Polymerase-1 Activity (PARP-1), on Locomotor Networks of the Rat Isolated Spinal Cord

Excitotoxicity is considered to be a major pathophysiological mechanism responsible for extensive neuronal death after acute spinal injury. The chief effector of such a neuronal death is thought to be the hyperactivation of intracellular PARP-1 that leads to cell energy depletion and DNA damage with the manifestation of non-apoptotic cell death termed parthanatos. An in vitro lesion model using the neonatal rat spinal cord has recently shown PARP-1 overactivity to be closely related to neuronal losses after an excitotoxic challenge by kainate: in this system the PARP-1 inhibitor 6(5H)-phenanthridinone (PHE) appeared to be a moderate histological neuroprotector. This article investigated whether PHE could actually preserve the function of locomotor networks in vitro from excitotoxicity. Bath-applied PHE (after a 60 min kainate application) failed to recover locomotor network function 24 h later. When the PHE administration was advanced by 30 min (during the administration of kainate), locomotor function could still not be recovered, while basic network rhythmicity persisted. Histochemical analysis showed that, even if the number of surviving neurons was improved with this protocol, it had failed to reach the threshold of minimal network membership necessary for expressing locomotor patterns. These results suggest that PARP-1 hyperactivity was a rapid onset mechanism of neuronal loss after an excitotoxic challenge and that more selective and faster-acting PARP-1 inhibitors are warranted to explore their potential neuroprotective role.     

Effect of butylated hydroxytoluene on cryopreservation of Boer goat semen in Tris egg yolk extender

The aim of this study was to determine the effect of butylated hydroxytoluene (BHT), a lipid-soluble anti-oxidant added in different concentrations to the Tris egg yolk extenders on semen cytological parameters pre freezing and post thawing (motility, morphology, viability, acrosome integrity and membrane integrity) of Boer goat spermatozoa. A total of 40 ejaculates from four Boer goat bucks were collected using an artificial vagina. Ten replicates of the ejaculates were diluted with a Tris egg yolk based extender which contained various concentrations (0.5mM, 1.0mM, 2.0mM and 3.0mM) of butylated hydroxytoluene while one sample was processed without supplementation of antioxidant and served as control. The diluted semen was cooled at 4°C and loaded into the straw and then stored in liquid nitrogen. It was evident that supplementation of BHT produces positive effect in terms of motility, membrane integrity and acrosome integrity in comparison with the control group in cooled and frozen Boer goat semen. Results showed significant differences in motility, membrane integrity, acrosome integrity and viability of cooled and frozen Boer goat spermatozoa at different concentrations. Motility, membrane integrity, acrosome integrity and viability was significantly higher in all treated groups than the control group (P<0.05) while there was no significant differences (P>0.05) in morphology trait between all group in cooled semen. However, improvement (P<0.05) was observed only in terms of the membrane integrity and acrosome integrity compared to the control and other treated groups in frozen semen. In conclusion, BHT can be used in cryopreservation of Boer goat semen in order to reduce the oxidative stress on spermatozoa.     

Chemical and genetic diversity of Zataria multiflora Boiss. accessions growing wild in Iran

Zataria multiflora Boiss. is an aromatic shrub belonging to the Lamiaceae family. Its aerial parts are used in the traditional medicine and in the pharmaceutical and food industries. The terpenoid and genetic profiles of 18 accessions of Z. multiflora, collected in different locations in Iran, have been analyzed by GC/FID and GC/MS or by AFLP (amplified fragment length polymorphism) analyses, respectively. Altogether, 56 compounds were identified in the essential oils, with the major constituents being thymol (6.0-54.9%), carvacrol (0.7-50.6%), linalool (1.2-46.8%), and p-cymene (1.6-14.8%). On the basis of the essential-oil composition, the 18 accessions were divided into four groups. The first group was characterized by a high content of carvacrol, thymol, and linalool, the second group was dominated by carvacrol, thymol, and p-cymene, the third group was characterized by a high concentration of thymol and a low content of carvacrol and p-cymene, and the forth group contained linalool and carvacrol as the main components. The AFLP results revealed that the average genetic similarity (GS) between the accessions was 0.61, ranging from 0.40 to 0.77. The UPGMA (unweighted pair-group method with arithmetic mean) cluster analysis divided all accessions into five groups at a similarity level of 0.60. The two clusters generated, the first based on the essential-oil compositions and the second on the AFLP data, showed a different pattern of relationships among the accessions. The knowledge of the Z. multiflora chemotype diversity, illustrated in this study, will allow an improvement of the homogeneity of the plant material for the production of different types of essential oils, depending on the demands of the pharmaceutical and food industries for specific uses.     

Comparative study of ammonium transporters in different organisms by study of a large number of structural protein features via data mining algorithms

Ammonium is an excellent nitrogen source, and ammonium transfer is a fundamental process in most organisms. Membrane transport of ammonium is the key component of nitrogen metabolism mediated by Ammonium Transporter/Methylamine Permease/Rhesus (AMT/MEP/Rh) protein family. Ammonium transporters play different physiological roles in various organisms. Here, we looked at the protein characteristics of ammonium transporters in different organisms to create a link between protein characteristics and the organism. In order to increase the accuracy and precision of the employed models, for the first time, an attempt was made to cover all structural aspects of ammonium transporters in animals, bacteria, fungi, plants, and human by extracting and calculating 874 protein attributes of primary, secondary, and tertiary structures for each ammonium transporter. Then, various weighting and modeling algorithms were applied to determine how structural protein features change between organisms. Considering a large number of protein attributes made it possible to detect key protein characteristics in the structure of ammonium transporters. The results, for the first time, indicated that His-based features including count/frequency of His and frequency/count of Ile-His were the most significant features generating different types of ammonium transporters within organisms. Within different tested models, the C5.0 model was the most efficient and precise model for discrimination of organism type, based on ammonium transporter sequence, with the precision of 94.85%. The determination of protein characteristics of ammonium transporters in different organisms provides a new vista for understanding the evolution of transporters based on the modulation of protein characteristics and facilitates engineering of new transporters. In our point of view, dissecting a large number of structural protein characteristics through data mining algorithms provides a novel functional strategy for studying evolution and phylogeny. This research will serve as a basis for future studies on engineering novel ammonium transporters.     

The Ecological Associations of Surface-Dwelling Lizards in Qom Province in the Northwest of Central Plateau of Iran

We used pitfall trapping to investigate the effects of elevation, plant density and soil structure on species diversity and the impact of these habitat factors on lizard habitat selectivity in the Qom Province in the Central Plateau of Iran. From a total of 12 1-ha plots, we captured 363 individuals of 15 species of lizards (six species of Lacertidae, five species of Agamidae, two species of Gekkonidae, one species of Varanidae and one species of Scincidae). A generalized linear model (GLM) determined that elevation was the most important factor impacting species diversity. The highest species diversity was at the intermediate elevation (1289 m). Abundance of 6 out of 15 species showed strong relationships with some habitat factors. These relationships were demonstrated by habitat selectivity index (Ivlev''s index). Our result supports other surveys that showed that elevation plays an important role in determining lizard species diversity.