Rational design of Striga hermonthica-specific seed germination inhibitors

The obligate hemiparasitic weed Striga hermonthica grows on cereal roots and presents a severe threat to global food security by causing enormous yield losses, particularly in sub-Saharan Africa. The rapidly increasing Striga seed bank in infested soils provides a major obstacle in controlling this weed. Striga seeds require host-derived strigolactones (SLs) for germination, and corresponding antagonists could be used as germination inhibitors. Recently, we demonstrated that the common detergent Triton X-100 is a specific inhibitor of Striga seed germination by binding noncovalently to its receptor, S. hermonthica HYPO-SENSITIVE TO LIGHT 7 (ShHTL7), without blocking the rice (Oryza sativa) SL receptor DWARF14 (OsD14). Moreover, triazole ureas, the potent covalently binding antagonists of rice SL perception with much higher activity toward OsD14, showed inhibition of Striga but were less specific. Considering that Triton X-100 is not suitable for field application and by combining structural elements of Triton and triazole urea, we developed two hybrid compounds, KK023-N1 and KK023-N2, as potential Striga-specific germination inhibitors. Both compounds blocked the hydrolysis activity of ShHTL7 but did not affect that of OsD14. Binding of KK023-N1 diminished ShHTL7 interaction with S. hermonthica MORE AXILLARY BRANCHING 2, a major component in SL signal transduction, and increased ShHTL7 thermal specificity. Docking studies indicate that KK023-N1 binding is not covalent but is caused by hydrophobic interactions. Finally, in vitro and greenhouse tests revealed specific inhibition of Striga seed germination, which led to a 38% reduction in Striga infestation in pot experiments. These findings reveal that KK023-N1 is a potential candidate for combating Striga and a promising basis for rational design and development of further Striga-specific herbicides.

Designed strigolactone antagonists inhibit Striga seed germination.     

Relationship Between IL-2, IL-17 Concentrations,and Serum Creatinine Levels in Men with Chronic Kidney Diseases

Background:Chronic kidney disease (CKD), is a major public health challenge worldwide. It is more prevalent in developed countries compared with the rest of the world, due to the higher rates of life expectancy and unhealthy lifestyle related factors. This aim of the current study is to evaluate the relationship between interleukins IL-2 and IL-17 concentrations and kidney function markers in men with CKD.Methods:Forty-five men with CKD and seventy controls were enrolled in the current study to assess the relationship between interleukin-2 (IL-2), interleukin-17 (IL-17), and CKD parameters. Fasting blood samples were collected from patients with CKD and their controls at same time. Serum IL-2, and IL-17 were measured in patients with CKD and their controls, and then the relationship between these interleukins and serum creatinine, serum urea, serum uric acid and urine albumin were evaluated.Results:A significant relationship was detected between IL-2 (p< 0.001), IL-17 (p< 0.001) levels and serum creatinine concentrations. The significant increase of IL-2 and IL-17 levels were also paralleled with a significant increase in serum urea (p< 0.001), and urine albumin (p< 0.001) concentrations respectively.Conclusion:IL-2 and IL-17 may play a critical role in the pathophysiology of CKD. The significant increase of IL-2 and IL-17 is associated with significantly high concentrations of creatinine, serum urea and urine albumin suggesting that these interleukins may be used as targets for future biomarkers and molecular therapy. However, due to limited sample size of the current study, larger prospective cohorts are needed to confirm these observations.Key Words: Chronic kidney disease, Interleukins, Serum creatinine, Serum urea, Urine albumin     

Effect of soil solarization on corn stalk rot

Seven weeks solarization of irrigated soil raised its temperature by 11.5°C over non-solarized soil at 10 cm depth and effectively controlled weeds (98.5%), stalk borer (8.9%) and stalk rot disease (69.1%) in corn. Solarization also reduced symptoms of Fusarium moniliforme and Macrophomina phaseolina significantly by 64.2% and 78.4%, respectively, and completely controlled M. phaseolina in corn cultivars, viz. Pool-10, Shaheen and Gauher. Whereas symptoms of F. moniliforme were observed in these cultivars, Fusarium graminearum was not observed except in two cultivars, Shaheen and Akbar. Growth of crop planted in solarized plots was better and it yielded almost one to three times more grains in cultivars under test. Soil analysis immediately following solarization revealed that essential elements were readily available in simpler forms, which may have increased pest resistance and reduced stalk breakage.     

Design of Miniaturized Double-Negative Material for Specific Absorption Rate Reduction in Human Head

In this study, a double-negative triangular metamaterial (TMM) structure, which exhibits a resounding electric response at microwave frequency, was developed by etching two concentric triangular rings of conducting materials. A finite-difference time-domain method in conjunction with the lossy-Drude model was used in this study. Simulations were performed using the CST Microwave Studio. The specific absorption rate (SAR) reduction technique is discussed, and the effects of the position of attachment, the distance, and the size of the metamaterials on the SAR reduction are explored. The performance of the double-negative TMMs in cellular phones was also measured in the cheek and the tilted positions using the COMOSAR system. The TMMs achieved a 52.28% reduction for the 10 g SAR. These results provide a guideline to determine the triangular design of metamaterials with the maximum SAR reducing effect for a mobile phone.     

Studies on the primary production of the river Shatt Al-Arab at Basrah,Iraq

The study was conducted on the Shatt Al-Arab River at Basrah, Iraq from September 1976 to August 1977 at three stations located at the upstream, middle and lowest parts of Basrah city. There was a bimodal seasonal variation of chlorophyll-a, the concentration of which ranged between 0.52–3.25 mg/m³. The gross primary production ranged between 6.03–37.02 mgC/m³/hr and showed a unimodal seasonal variation with a maximum in August. From the concentration of chlorophyll-a and from measurement of primary productivity it was clear that the section of the river at the upstream end of Basrah city was poorest and that at the middle of the Basrah city below Ashar Channel was the richest. A positive corelation between primary productivity and chlorophyll-a.     

Toxoplasma gondii stimulates the release of 13- and 9-hydroxyoctadecadienoic acids by human platelets.

We have recently demonstrated a novel cytotoxic effect of human platelets against Toxoplasma gondii and a role for thromboxane (TX) in this process (Yong et al., 1991). We now report on the spectrum of lipid mediators released by human platelets after interaction with T. gondii. In addition to TXB2, human platelets after incubation with T. gondii for 90 min released 12-hydroxyheptadecatrienoic acid (12-HHT), 12-hydroxyeicosatetraenoic acid (12-HETE), and an unidentified peak (UVmax 234 nm) as determined by reverse-phase high-performance liquid chromatography. Thermospray-liquid chromatography/mass spectrometry analysis and straight-phase HPLC identified the unknown peak as a mixture of 13-hydroxyoctadecadienoic acid (HODE) and 9-HODE. Radiolabeling studies with [14C]linoleic acid indicated that the platelets were the cellular source of the octadecanoids with 13-HODE (87.7%) greater than 9-HODE (12.3%). Inhibitor studies with indomethacin indicated that 13-HODE was a lipoxygenase product and 9-HODE was a cyclooxygenase product of linoleic acid. Thus, Toxoplasma-stimulated platelets release oxygenated products of both arachidonic acid and linoleic acid which may be important in the host response to T. gondii infection.     

High level expression of peptides and proteins using cytochrome b5 as a fusion host

A novel fusion protein system based on the highly soluble heme-binding domain of cytochrome b5 has been designed. The ability of cytochrome b5 to increase the levels of expression and solubility of target proteins has been tested by expressing several proteins and peptides, viz., alpha hemoglobin stabilizing protein, the regulatory subunits of acetohydroxy acid synthase I (ilvM) and II (ilvN), the carboxy terminal domains of mouse neuronal kinesin and pantothenate synthatase, two peptide toxins from cone snails, and the inactivation gate from the brain voltage gated sodium channel, NaV1.2. The fusion protein system has been designed to incorporate protease cleavage sites for commonly used proteases, viz., enterokinase, Factor Xa, and Tobacco etch virus protease. Accumulation of expressed protein as a function of time may be visually ascertained by the fact that the cells take on a bright red color during the course of induction. In all the cases tested so far, the fusion protein accumulates in the soluble fraction to high levels. A novel purification protocol has been designed to purify the fusion proteins using metal affinity chromatography, without the need of a hexahistidine-tag. Mass spectral analysis has shown that the fusion proteins are of full length. CD studies have shown that the solubilized fusion proteins are structured. The proteins of interest may be cleaved from the parent protein by either chemical or enzymatic means. The results presented here demonstrate the versatility of the cytochrome b5 based fusion system for the production of peptides and small proteins (<15 kDa).     

Chromium-resistant bacteria and cyanobacteria: impact on Cr(VI) reduction potential and plant growth

Two chromium-resistant bacterial strains, Bacillus cereus S-6 and Ochrobactrum intermedium CrT-1, and two cyanobacterial strains, Oscillatoria sp. and Synechocystis sp., were used in this study. At initial chromate concentrations of 300 and 600 microg K2CrO4 mL(-1), and an inoculum size of 9.6 x 10(7) cells mL(-1), B. cereus S-6 completely reduced Cr(VI), while O. intermedium CrT-1 reduced Cr(VI) by 98% and 70%, respectively after 96 h. At 100 microg K2CrO4 mL(-1), Synechocystis sp. MK(S) and Oscillatoria sp. BJ2 reduced 62.1% and 39.9% of Cr(VI), respectively, at 30 degrees C and pH 8. Application of hexavalent chromate salts adversely affected wheat seedling growth and anatomical characters. However, bacterial inoculation alleviated the toxic effects, as reflected by significant improvements in growth as well as anatomical parameters. Cyanobacterial strains also led to some enhancement of various growth parameters in wheat seedlings.     

Characterization of the G alpha(s) regulator cysteine string protein

Cysteine string protein (CSP) is an abundant regulated secretory vesicle protein that is composed of a string of cysteine residues, a linker domain, and an N-terminal J domain characteristic of the DnaJ/Hsp40 co-chaperone family. We have shown previously that CSP associates with heterotrimeric GTP-binding proteins (G proteins) and promotes G protein inhibition of N-type Ca2+ channels. To elucidate the mechanisms by which CSP modulates G protein signaling, we examined the effects of CSP(1-198) (full-length), CSP(1-112), and CSP(1-82) on the kinetics of guanine nucleotide exchange and GTP hydrolysis. In this report, we demonstrate that CSP selectively interacts with G alpha(s) and increases steady-state GTP hydrolysis. CSP(1-198) modulation of G alpha(s) was dependent on Hsc70 (70-kDa heat shock cognate protein) and SGT (small glutamine-rich tetratricopeptide repeat domain protein), whereas modulation by CSP(1-112) was Hsc70-SGT-independent. CSP(1-112) preferentially associated with the inactive GDP-bound conformation of G alpha(s). Consistent with the stimulation of GTP hydrolysis, CSP(1-112) increased guanine nucleotide exchange of G alpha(s). The interaction of native G alpha(s) and CSP was confirmed by coimmunoprecipitation and showed that G alpha(s) associates with CSP. Furthermore, transient expression of CSP in HEK cells increased cellular cAMP levels in the presence of the beta2 adrenergic agonist isoproterenol. Together, these results demonstrate that CSP modulates G protein function by preferentially targeting the inactive GDP-bound form of G alpha(s) and promoting GDP/GTP exchange. Our results show that the guanine nucleotide exchange activity of full-length CSP is, in turn, regulated by Hsc70-SGT.