Salicylic acid induced changes on some physiological parameters symptomatic for oxidative stress and mineral nutrition in maize (Zea mays L.) grown under salinity

It has been proposed that salicylic acid (SA) acts as an endogenous signal molecule responsible for inducing abiotic stress tolerance in plants. The effect of varying salicylic acid (SA) supply (0, 0.1, 0.5 and 1.0mM) on growth, mineral uptake, membrane permeability, lipid peroxidation, H(2)O(2) concentration, UV-absorbing substances, chlorophyll and carotenoid concentrations of NaCl (40 mM) stressed maize (Zea mays L.) was investigated. Exogenously applied SA increased plant growth significantly both in saline and non-saline conditions. As a consequence of salinity stress, lipid peroxidation, measured in terms of malondialdehyde (MDA) content and membrane permeability was decreased by SA. UV-absorbing substances (UVAS) and H(2)O(2) concentration were increased by increasing levels of SA. SA also strongly inhibited Na(+) and Cl(-) accumulation, but stimulated N, Mg, Fe, Mn and Cu concentrations of salt stressed maize plants. These results suggest that SA could be used as a potential growth regulator to improve plant salinity stress resistance.     

Persistence of hyperbaric oxygen-induced oxidative effects after exposure in rat brain cortex tissue

Hyperbaric oxygen (HBO) causes oxidative stress in several organs and tissues. Due to its high rate of blood flow and oxygen consumption, the brain is one of the most sensitive organs to this effect. Many studies have reported oxidative effects of HBO, but there is no comprehensive data about how long this effect persists. The aim of this study was to elucidate the duration of HBO-induced oxidative/antioxidant action. Male Sprague-Dawley rats were divided into 5 groups. Except for the controls, the animals were subjected to 100% oxygen for 2 h at 3 atm and differed from each other by the time to dissection after exposure that began at 30, 60, 90, or 120 min. Thiobarbituric acid-reactive substances (TBARS), as well as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity was determined in brain cortex tissue. Additionally, nitrite-nitrate (NO(x)) concentrations were measured. All measured parameters were found to be significantly increased 30 min after exposure. SOD and GSH-Px levels persisted at significantly high levels for 60 min. In conclusion, the oxidative effect of HBO was shown to persist only for 1 h. Further studies should be performed to elucidate the possible molecular interactions during this period.     

Comparative evaluation of hepatotoxic and nephrotoxic effects of aroclors 1221 and 1254 in female rats

Polychlorinated biphenyls (PCBs) are persistent environmental pollutants. This study compared effects of two PCB mixtures, Aroclors 1221 (A1221) and 1254 (A1254) on serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), urea, creatinine and uric acid in female rats. Histopathological changes in the liver and kidney were also examined. A group of adult Wistar rats served as controls. Groups II and III were subcutaneously injected with A1221 and A1254 at 10 mg/kg every other day for 6 weeks. At the end of this period, all animals were decapitated and blood samples were collected. Serum urea, creatinine, uric acid, ALT, AST and ALP levels were determined. Liver and kidney were collected for histopathological examination. They were fixed in formaldehyde and processed for light microscopy. Both A1221 and 1254 significantly elevated serum ALT (p < 0.05) and AST (p < 0.01) levels compared to the control group. Serum ALP values were significantly increased by A1221 (p < 0.05), but they were unaffected in the A1254 group. Treatment with both A1221 and A1254 significantly increased serum levels of urea (p < 0.05), creatinine (p < 0.01) and uric acid (except in the A1221 group; p < 0.005). Distinct histopathological changes including renal corpuscular atrophy, peritubular vascular congestion and dilated cortical tubules, sinusoidal dilatation, congestion and mononuclear cell infiltration were observed. These findings suggest that PCBs may cause nephrotoxicity and hepatotoxicity in female rats.     

The effect of aminoguanidine against cholestatic liver injury in rats

We investigated the protective role of aminoguanidine (AG) in rat liver injury induced by chronic biliary obstruction. Secondary biliary cirrhosis was induced by bile duct ligation for 14 days. Swiss albino rats were divided into three groups: Common bile duct ligated (CBDL) rats; Group A, CBDL rats treated with AG as Group B and simple laparotomy group known as the Sham group; Group C. Group B received 200 mg/kg of AG intraperitoneally daily throughout 14 days. The present data showed decreased gama glutamyl transferase (GGT), aspartate aminotransferase (AST), bilirubin and alanine aminotransferase (ALT) levels in the AG treated rats, when compared with CBDL rats (p < 0.05). In the AG treated rats, tissue levels of malondialdehyde (MDA) were significantly lower than that in CBDL rats (p < 0.001). Although the levels of glutathione (GSH) in AG treated rats were higher and myeloperoxidase (MPO) were lower than that in CBDL rats, the difference was not statistically significant (p > 0.05). The levels of interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha) were significantly lower and although the levels of interleukin-6 (IL-6) were lower in AG treated rats than that in CBDL rats, the difference was not statistically significant. Administration of AG in the rats with biliary obstruction resulted in inhibition of ductular proliferation and portal inflammation. The present study demonstrates that intraperitoneal administration of AG in CBDL rats maintains antioxidant defenses, reduces liver oxidative and cytokine damage and ductular proliferation and portal inflammation. This effect of AG may be useful in the preservation of liver injury in cholestasis.     

Univalent binding of the Cry1Ab toxin of Bacillus thuringiensis to a conserved structural motif in the cadherin receptor BT-R1

The Cry1Ab toxin produced by Bacillus thuringiensis (Bt) exerts insecticidal action upon binding to BT-R1, a cadherin receptor localized in the midgut epithelium of the tobacco hornworm Manduca sexta [Dorsch, J. A., Candas, M., Griko, N. B., Maaty, W. S., Midboe, E. G., Vadlamudi, R. K., and Bulla, L. A., Jr. (2002) Cry1A toxins of Bacillus thuringiensis bind specifically to a region adjacent to the membrane-proximal extracellular domain of BT-R1 in Manduca sexta: involvement of a cadherin in the entomopathogenicity of Bacillus thuringiensis, Insect Biochem. Mol. Biol. 32, 1025-1036]. BT-R1 represents a family of invertebrate cadherins whose ectodomains (ECs) are composed of multiple cadherin repeats (EC1 through EC12). In the present work, we determined the Cry1Ab toxin binding site in BT-R1 in the context of cadherin structural determinants. Our studies revealed a conserved structural motif for toxin binding that includes two distinct regions within the N- and C-termini of EC12. These regions are characterized by unique sequence signatures that mark the toxin-binding function in BT-R1 as well as in homologous lepidopteran cadherins. Structure modeling of EC12 discloses the conserved motif as a single broad interface that holds the N- and C-termini in close proximity. Binding of toxin to BT-R1, which is univalent, and the subsequent downstream molecular events responsible for cell death depend on the conserved motif in EC12.     

Identifying genes underlying skin pigmentation differences among human populations

Skin pigmentation is a human phenotype that varies greatly among human populations and it has long been speculated that this variation is adaptive. We therefore expect the genes that contribute to these large differences in phenotype to show large allele frequency differences among populations and to possibly harbor signatures of positive selection. To identify the loci that likely contribute to among-population human skin pigmentation differences, we measured allele frequency differentiation among Europeans, Chinese and Africans for 24 human pigmentation genes from 2 publicly available, large scale SNP data sets. Several skin pigmentation genes show unusually large allele frequency differences among these populations. To determine whether these allele frequency differences might be due to selection, we employed a within-population test based on long-range haplotype structure and identified several outliers that have not been previously identified as putatively adaptive. Most notably, we identify the DCT gene as a candidate for recent positive selection in the Chinese. Moreover, our analyses suggest that it is likely that different genes are responsible for the lighter skin pigmentation found in different non-African populations. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Evaluation of the gonial angle in the Anatolian populations: from past to present

Biometrical studies on ancient skeletal series and comparison with modern people by using radiological methods are quite limited in Turkey. Previous studies showed that measurements obtained from orthopantomographs are highly correlated with the actual size of the bones. The aim of the present study is to determine the possible change in gonial angle over time in ancient Anatolian populations with the present. Also an aim was attempted to demonstrate the symmetry of the gonial angle in the jaws and the sexual dimorphism. Gonial angle values (right and left) were taken from 267 Turkish adults with no craniomandibular disorders, orthodontic history or treatment by using panoramic radiographs. Data of the past populations were collected from previous studies. Comparison between right and left sides and the sexual differences were tested by paired student t-test and discriminant analyses were conducted. The results showed that there were no significant differences between the right and left gonial angles of the individuals but there was a significant difference at the left gonial angle between sexes (p < 0.01). Furthermore, no statistically significant difference was found for the gonial angle between the selected past populations with the present sample.     

Fire resistance of Douglas fir (Pseudotsuga menzieesi) treated with borates and natural extractives

The objective of this study was to determine fire resistance of Douglas fir (Pseudotsuga menzieesi (Mirb.) Franco) specimens treated with borate supplemented aqueous solutions of brutia pine bark powder, acorn powder, sumach leaf powder, and gall-nut powder. Boric acid (BA) and borax (BX) were used as borates which are the most commonly used fire retardants in wood preservation industry. Natural extractives (brutia pine bark powder, sumach leaf powder, acorn powder, and gall-nut powder) were also used which have toxic efficiency against insects and fungi due to their tannin contents. A commercial treatment compound Tanalith-CBC (copper-borate-chromate), which is an impregnation chemical, is used for comparison. The fire test method was performed in three stages: flame stage, without flame stage, and glowing stage. Results indicated that the lowest temperature for flame stage, without flame stage, and glowing stage were obtained for specimens treated with BA and BX mixture (7:3; weight:weight). The lowest mass loss was found for the specimens treated with a mixture of BA and BX. Natural extractives did not improve fire resistance of the samples. However, boric acid and borax had excellent fire retardant effectiveness over untreated and treated samples with natural extractives.     

Site-directed mutagenesis of five conserved residues of subunit i of the cytochrome cbb3 oxidase in Rhodobacter capsulatus

Cytochrome cbb(3) oxidase is a member of the heme-copper oxidase superfamily that catalyses the reduction of molecular oxygen to the water and conserves the liberated energy in the form of a proton gradient. Comparison of the amino acid sequences of subunit I from different classes of heme-copper oxidases showed that transmembrane helix VIII and the loop between transmembrane helices IX and X contain five highly conserved polar residues; Ser333, Ser340, Thr350, Asn390 and Thr394. To determine the relationship between these conserved amino acids and the activity and assembly of the cbb(3) oxidase in Rhodobacter capsulatus, each of these five conserved amino acids was substituted for alanine by site-directed mutagenesis. The effects of these mutations on catalytic activity were determined using a NADI plate assay and by measurements of the rate of oxygen consumption. The consequence of these mutations for the structural integrity of the cbb(3) oxidase was determined by SDS-PAGE analysis of chromatophore membranes followed by TMBZ staining. The results indicate that the Asn390Ala mutation led to a complete loss of enzyme activity and that the Ser333Ala mutation decreased the activity significantly. The remaining mutants cause a partial loss of catalytic activity. All of the mutant enzymes, except Asn390Ala, were apparently correctly assembled and stable in the membrane of the R. capsulatus.     

Ghrelin is present in teeth

Ghrelin belongs to the family of a gut-brain hormone that promotes food intake and controls energy balance. Recently, it has also been shown to regulate bone formation directly. Dental tissue shares several functional, developmental and anatomical similarities with bone, and in the present study we have investigated the presence of ghrelin in 44 human teeth using immunocytochemistry and radioimmunoassay. Both methods showed that the hormone is present in canines and molars, mainly in the odontoblasts but also in the pulp. Ghrelin could potentially play interesting physiological roles in teeth.