Composition and antimicrobial activity of the essential oil of Dicyclophora persica Boiss. from Iran

The chemical composition of the essential oil of Dicyclophora persica Boiss. was identified by GC and GC-MS analysis. The analysis of the oil resulted in the identification of forty-five components constituting 98.6% of the total oil. The main constituents were a-pinene (31.5%), (Z)-beta-ocimene (23.3%), p-cymene (6.7%) and (E)-beta-ocimene (5.4%). The antimicrobial activity of the oil was tested by the disk diffusion method against four Gram-positive (Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis) and three Gram-negative (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) bacteria together with a fungus (Aspergillus niger). The oil showed strong inhibition activity toward all the tested microorganisms except for Pseudomonas aeruginosa.     

Plasticity in interactions of fibroblast growth factor 1 (FGF1) N terminus with FGF receptors underlies promiscuity of FGF1

Tissue-specific alternative splicing in the second half of Ig-like domain 3 (D3) of fibroblast growth factor receptors 1–3 (FGFR1 to -3) generates epithelial FGFR1b-FGFR3b and mesenchymal FGFR1c-FGFR3c splice isoforms. This splicing event establishes a selectivity filter to restrict the ligand binding specificity of FGFRb and FGFRc isoforms to mesenchymally and epithelially derived fibroblast growth factors (FGFs), respectively. FGF1 is termed the “universal FGFR ligand” because it overrides this specificity barrier. To elucidate the molecular basis for FGF1 cross-reactivity with the “b” and “c” splice isoforms of FGFRs, we determined the first crystal structure of FGF1 in complex with an FGFRb isoform, FGFR2b, at 2.1 Å resolution. Comparison of the FGF1-FGFR2b structure with the three previously published FGF1-FGFRc structures reveals that plasticity in the interactions of the N-terminal region of FGF1 with FGFR D3 is the main determinant of FGF1 cross-reactivity with both isoforms of FGFRs. In support of our structural data, we demonstrate that substitution of three N-terminal residues (Gly-19, His-25, and Phe-26) of FGF2 (a ligand that does not bind FGFR2b) for the corresponding residues of FGF1 (Phe-16, Asn-22, and Tyr-23) enables the FGF2 triple mutant to bind and activate FGFR2b. These findings taken together with our previous structural data on receptor binding specificity of FGF2, FGF8, and FGF10 conclusively show that sequence divergence at the N termini of FGFs is the primary regulator of the receptor binding specificity and promiscuity of FGFs.     

Metabolism of chlorobiphenyls by a variant biphenyl dioxygenase exhibiting enhanced activity toward dibenzofuran

The biphenyl dioxygenase of Burkholderia xenovorans LB400 (BphAE(LB400)) catalyzes the dihydroxylation of biphenyl and of several polychlorinated biphenyls (PCBs) but it poorly oxidizes dibenzofuran. In this work we showed that BphAE(RR41), a variant which was previously found to metabolize dibenzofuran more efficiently than its parent BphAE(LB400), metabolized a broader range of PCBs than BphAE(LB400). Hence, BphAE(RR41) was able to metabolize 2,6,2',6'-, 3,4,3',5'- and 2,4,3',4'-tetrachlorobiphenyl that BphAE(LB400) is unable to metabolize. BphAE(RR41) was obtained by changing Thr335Phe336Asn338Ile341Leu409 of BphAE(LB400) to Ala335Met336Gln338Val341Phe409. Site-directed mutagenesis was used to create combinations of each substitution, in order to assess their individual contributions. Data show that the same Asn338Glu/Leu409Phe substitution that enhanced the ability to metabolize dibenzofuran resulted in a broadening of the PCB substrates range of the enzyme. The role of these substitutions on regiospecificities toward selected PCBs is also discussed.     

Serum Iron,Zinc, and Copper Concentration in Premature Graying of Hair

Premature graying of hair with unclear etiology, which is known as premature canities, is a common cause of referrals to the dermatologists. We assessed the relationship between serum iron, copper, and zinc concentrations with premature canities. This study was conducted on patients under 20 years old suffering from premature canities, having a minimum of ten gray hair fibers, and referring to university hospitals of Isfahan (Iran). The results were compared with age–sex-matched controls. Demographic data and disease characteristics were recorded for two groups. We studied serum iron, copper, and zinc concentrations of 66 patients and 66 controls using atomic absorption and Ferrozine methods. The mean age of studied cases was 17.8 ± 2.0 years, and the mean age of the onset of canities was 15.5 ± 3.2 years with no significant difference between males and females (P > 0.05). Serum copper concentration was significantly lower in patients compared with controls (90.7 ± 37.4 vs. 105.3 ± 50.2 μg/dL, P = 0.048), but serum iron concentration was significantly lower in controls compared to patients (88.8 ± 39.5 vs. 108.3 ± 48.4 μg/dL, P = 0.008). Also, there was no significant difference between patients and controls in serum zinc concentration (114.8 ± 67.8 vs. 108.2 ± 49.9 μg/dL, P = 0.285). According to these results, among copper, zinc, and iron, a low serum copper concentration may play a role in premature graying of hairs in our society. Further studies are needed to find the underlying mechanism of this relationship.     

Klotho coreceptors inhibit signaling by paracrine fibroblast growth factor 8 subfamily ligands

It has been recently established that Klotho coreceptors associate with fibroblast growth factor (FGF) receptor tyrosine kinases (FGFRs) to enable signaling by endocrine-acting FGFs. However, the molecular interactions leading to FGF-FGFR-Klotho ternary complex formation remain incompletely understood. Here, we show that in contrast to αKlotho, βKlotho binds its cognate endocrine FGF ligand (FGF19 or FGF21) and FGFR independently through two distinct binding sites. FGF19 and FGF21 use their respective C-terminal tails to bind to a common binding site on βKlotho. Importantly, we also show that Klotho coreceptors engage a conserved hydrophobic groove in the immunoglobulin-like domain III (D3) of the "c" splice isoform of FGFR. Intriguingly, this hydrophobic groove is also used by ligands of the paracrine-acting FGF8 subfamily for receptor binding. Based on this binding site overlap, we conclude that while Klotho coreceptors enhance binding affinity of FGFR for endocrine FGFs, they actively suppress binding of FGF8 subfamily ligands to FGFR.     

Some physiological responses of chickpea cultivars to arbuscular mycorrhiza under drought stress

A factorial experiment based on RCB design with three replicates was conducted to investigate changes in some physiological responses of two chickpea (Cicer arietinum L.) cultivars (Pirouz from Desi type and ILC482 from Kabuli type) to arbuscular mycorrhiza (Glomus etunicatum Becker and Gerdman) under different irrigation treatments. The experiment was carried out in the greenhouse of the Agricultural Faculty of Kurdistan University from April to August 2009. The results showed that leaf chlorophyll content of chickpea cultivars was significantly increased by arbuscular mycorrhiza (AM) under both well and limited irrigation conditions. Proline accumulation in chickpea leaves under moderate and severe drought stresses was significantly stronger than that under optimum irrigation. Inoculation of chickpea with mycorrhizal fungi caused an increase in the activities of polyphenol oxidase and peroxidase, but a decrease in the activity of catalase. Comparisons among different irrigation levels showed that chickpea plants under drought stress had the most active lipid peroxidation. Non-AM plants showed stronger lipid peroxidation under moderate and severe water stresses than AM plants. Lipid peroxidation was more active in Pirouz leaves than in ILC₄₈₂ leaves. It seems that Kabuli-type cultivar responded better to mycorrhizal symbiosis under drought stress than Desitype cultivar.     

A Potential Association between Helicobacter pylori CagA EPIYA and Multimerization Motifs with Cytokeratin 18 Cleavage Rate during Early Apoptosis

Background and Aims: Helicobacter pylori is a highly diverse pathogen, which encounters epithelial cells as the initial defense barrier during its lifelong infection. The structure of epithelial cells can be disrupted through cleavage of microfilaments. Cytokeratin 18 (CK18) is an intermediate filament, the cleavage of which is considered an early event during apoptosis following activation of effector caspases. Methods: Helicobacter pylori strains were isolated from 76 dyspeptic patients. cagA 3’ variable region and CagA protein status were analyzed by PCR and western blotting, respectively. Eight hours post‐co‐culture of AGS cells with different H. pylori strains, flow cytometric analysis was performed using M30 monoclonal antibody specific to CK18 cleavage‐induced neo‐epitope. Results: Higher rates of CK18 cleavage were detected during co‐culture of AGS cells with H. pylori strains bearing greater numbers of cagA EPIYA‐C and multimerization (CM) motifs. On the other hand, H. pylori strains with greater numbers of EPIYA‐B relative to EPIYA‐C demonstrated a decrease in CK18 cleavage rate. Thus, H. pylori‐mediated cleavage of CK18 appeared proportional to the number of CagA EPIYA‐C and CM motifs, which seemed to be downplayed in the presence of EPIYA‐B motifs. Conclusions: Our observation associating the heterogeneity of cagA variants with the potential of H. pylori strains in the induction of CK18 cleavage as an early indication of apoptosis in gastric epithelial cells supports the fact that apoptosis may be a type‐specific trait. However, additional cagA‐targeted experiments are required to clearly identify the role of EPIYA and CM motifs in apoptosis and/or the responsible effector molecules.