Comparison of organic and inorganic amendments for enhancing soil lead phytoextraction by wheat (Triticum aestivum L.)

Phytoextraction has received increasing attention as a promising, cost-effective alternative to conventional engineering-based remediation methods for metal contaminated soils. In order to enhance the phytoremediative ability of green plants chelating agents are commonly used. Our study aims to evaluate whether, citric acid (CA) or elemental sulfur (S) should be used as an alternative to the ethylene diamine tetraacetic acid (EDTA)for chemically enhanced phytoextraction. Results showed that EDTA was more efficient than CA and S in solubilizing lead (Pb) from the soil. The application of EDTA and S increased the shoot biomass of wheat. However, application of CA at higher rates (30 mmol kg(-1)) resulted in significantly lower wheat biomass. Photosynthesis and transpiration rates increased with EDTA and S application, whereas these parameters were decreased with the application of CA. Elemental sulfur was ineffective for enhancing the concentration of Pb in wheat shoots. Although CA did not increase the Pb solubility measured at the end of experiment, however, it was more effective than EDTA in enhancing the concentration of Pb in the shoots of Triticum aestivum L. It was assumed that increase in Mn concentration to toxic levels in soil with CA addition might have resulted in unusual Pb concentration in wheat plants. The results of the present study suggest that under the conditions used in this experiment, CA at the highest dose was the best amendment for enhanced phytoextraction of Pb using wheat compared to either EDTA or S.     

Do physiological roles foster persistence of drug/multidrug-efflux transporters? A case study

Drug and multidrug resistance have greatly compromised the compounds that were once the mainstays of antibiotic therapy. This resistance often persists despite reductions in the use of antibiotics, indicating that the proteins encoded by antibiotic-resistance genes have alternative physiological roles that can foster such persistence in the absence of selective pressure by antibiotics. The recent observations that Tet(L), a tetracycline-efflux transporter, and MdfA, a multidrug-efflux transporter, both confer alkali tolerance offer a striking case study in support of this hypothesis.     

Zinc-regulating proteins, ZnT-1, and metallothionein I/II are present in different cell populations in the mouse testis.

Zinc ions play an important role in testis development and spermatogenesis. Thus, nutritional zinc deficiency leads to aberrant testicular development, reduced spermatogenesis, and male sterility. The precise actions of zinc in mediating these functions and the mechanisms by which zinc is itself regulated in the testis, however, have not been adequately elucidated. We have assessed the distribution of the zinc-regulating proteins ZnT-1 and metallothionein I/II (MT I/II) in the mouse seminiferous tubule. Co-labeling for ZnT-1 and MT I/II demonstrated unique patterns of distribution for these proteins, with ZnT-1 present in Sertoli cells in addition to luminal spermatozoa and MT I/II restricted to spermatocytes. These findings were confirmed by dual-label immunofluorescence for ZnT-1 and the Sertoli cell marker, vimentin, and by immunoelectron microscopy. The differential expression patterns of ZnT-1 and MTs support the hypothesis that ZnT-1 and MTs play different roles in the regulation of intracellular zinc in this organ. The specific expression of ZnT-1 in the Sertoli cells, moreover, is consistent with their role in maintaining a nurturing, closely regulated environment for spermatogenesis.     

A leukotriene receptor antagonist modulates iNOS in the lung and in a leukotriene-free cell model.

Nitric oxide (NO), an important cell signaling molecule, is considered a marker of inflammatory response and is elevated in asthmatics. This study investigated the effects of montelukast (a leukotriene receptor antagonist) on iNOS expression and activity in a Brown Norway (BN) rat allergic inflammation model and in L2 lung epithelial cells. Allergic inflammation was induced by ovalbumin (OVA) injection in BN rats followed by treatment with either montelukast or dexamethasone (DX). Allergen inhalation was performed, and post-allergen Penh was measured 5 min after the challenge. Cysteinyl leukotriene levels were measured in bronchoalveolar lavage (BAL) fluid and lung iNOS expression and activity determined. These parameters were also measured in cytokine stimulated L2 lung epithelial cells. iNOS expression was significantly higher in OVA challenged rats compared to the naive, DX, and montelukast treated groups, as confirmed by immunohistochemistry and Western blot analysis. However, no significant differences in NOS activity were found. Cysteinyl leukotriene measured in BAL was significantly higher in all OVA challenged rats compared to naive controls. Incubation of L2 cells with a mixture of interferon gamma (IFNgamma), lipopolysaccharide (LPS), and tumor necrosis factor (TNFalpha) resulted in high levels of nitrite formation resulting from iNOS induction. Treatment of cytokine stimulated cells with DX or montelukast significantly decreased iNOS expression and activity. No detectable cysteinyl leukotrienes were found in the supernatant fluid of L2 cells. This study confirms the ability of montelukast to modulate iNOS function and raises the possibility that changes in iNOS expression and activity may occur via pathways independent of cysteinyl leukotrienes.     

Deciphering role of technical bioprocess parameters for bioethanol production using microalgae

Microalgae biomass is considered an important feedstock for biofuels and other bioactive compounds due to its faster growth rate, high biomass production and high biomolecules accumulation over first and second-generation feedstock. This research aimed to maximize the specific growth rate of fresh water green microalgae Closteriopsis acicularis, a member of family Chlorellaceae under the effect of pH and phosphate concentration to attain enhanced biomass productivity. This study investigates the individual and cumulative effect of phosphate concentration and pH on specific growth characteristics of Closteriopsis acicularis in autotrophic mode of cultivation for bioethanol production. Central-Composite Design (CCD) strategy and Response Surface Methodology (RSM) was used for the optimization of microalga growth and ethanol production under laboratory conditions. The results showed that high specific growth rate and biomass productivity of 0.342 day⁻¹ and 0.497 g L⁻¹ day⁻¹ respectively, were achieved at high concentration of phosphate (0.115 g L⁻¹) and pH (9) at 21st day of cultivation. The elemental composition of optimized biomass has shown enhanced elemental accumulation of certain macro (C, O, P) and micronutrients (Na, Mg, Al, K, Ca and Fe) except for nitrogen and sulfur. The Fourier transform infrared spectroscopic analysis has revealed spectral peaks and high absorbance in spectral range of carbohydrates, lipids and proteins, in optimized biomass. The carbohydrates content of optimized biomass was observed as 58%, with 29.3 g L⁻¹ of fermentable sugars after acid catalyzed saccharification. The bioethanol yield was estimated as 51 % g ethanol/g glucose with maximum of 14.9 g/L of bioethanol production. In conclusion, it can be inferred that high specific growth rate and biomass productivity can be achieved by varying levels of phosphate concentration and pH during cultivation of Closteriopsis acicularis for improved yield of microbial growth, biomass and bioethanol production.     

Theoretical insights into thermal cyclophanediene to dihydropyrene electrocyclic reactions; a comparative study of Woodward Hoffmann allowed and forbidden reactions

The thermally allowed electrocyclic reaction syn-cyclophanediene (CPD) to dihydropyrene (DHP) was compared with the disallowed thermal electrocyclic reaction in anti CPD through density functional theory (DFT) calculations at the B3LYP/6-31?+?G(d) level. Moreover, the results were also compared with the electrocyclization of 1,3,5 hexatriene to 1,3-cyclohexadiene . The Woodward-Hoffmann (W-H) allowed thermal reaction in syn CPD 11 has a calculated activation barrier of 6.23 kcal mol^?1, compared with 29 kcal mol^?1 for the electrocyclization of 1,3,5 hexatriene to 1,3-cyclohexadiene. The enhanced acceleration of electrocyclization is believed to arise from geometrically enforced spatially aligned termini of the hexatriene. Substituents at the electrocyclic terminus of cyclophanediene significantly affected (up to three fold) the activation barriers. Mono-substitution of CPD has substituent dependent acceleration or deceleration whereas di-substitution always increased the activation barrier. The activation barrier for electrocyclization in 33 is 4.44 kcal mol^?1, which is the lowest activation barrier for any thermal electrocyclic reaction. Cyclophanedienes (CPDs) substituted with electron-rich substituents cyclized with high activation barriers and vice versa, a phenomenon significantly different from electrocyclic reaction of 1,3,5-hexatriene where no such trend is traceable. Comparison of W-H allowed and forbidden electrocyclization in syn and anti CPDs, respectively, revealed quite similar electronic demand, although the transition states are different in nature. The transition state for a W-H forbidden reaction is biradicaloid, with most of the spin density at the electrocyclic termini; however, the transition state for a W-H allowed reaction has no such contribution. We also believe that this is the first study of its type, where W-H allowed and forbidden reactions are compared on a similar set of molecules, and compared for electronic effect through substituents.     

Unraveling bovin phylogeny: accomplishments and challenges

The phylogenetic systematics of bovin species forms a common basis for studies at multiple scales, from the level of domestication in populations to major cladogenesis. The main big-picture accomplishments of this productive field, including two recent works, one in BMC Genomics, are reviewed with an eye for some of the limitations and challenges impeding progress. See Research article http://www.biomedcentral.com/1471-2164/10/177     

Identification and characterization of the Escherichia coli stress protein UP12, a putative in vivo substrate of GroEL.

Many groups of proteins play important roles in the cell's response to various stresses. The molecular chaperone GroEL of Escherichia coli represents one such highly conserved family of stress proteins. We have observed that isolated GroEL complexes from stationary cultures contain various polypeptides that can be released from the chaperonin by GroES and/or ATP, and identified two such polypeptides as the proteins GatY and UP12. Whereas GatY had been isolated previously, as an in vivo substrate of GroEL, the isolation of UP12 in a complex with GroEL was intriguing, because based on sequence similarity it was suggested that UP12 might also be a functional stress protein. UP12 belongs to a family of universal stress proteins (UspA family), of which UspA itself, and three additional paralogues, have been characterized previously. Here we show that UP12 accumulates under various growth inhibitory conditions and induced by heat shock. Furthermore, unlike wild-type cells, a UP12 deletion mutant recovers slowly from late stationary growth conditions, and has a marked sensitivity to the toxic agent carbonyl cyanide m-chlorophenyl hydrazone (CCCP). Finally, coimmunoprecipitation experiments confirmed the initial observation that UP12 interacts with GroEL. Therefore, we suggest that UP12 may function as a universal stress protein, interaction of which with GroEL possibly ensures its proper folding state.     

Assessment of toxicity of volatile fatty acids to Photobacterium phosphoreum

The toxicity of four volatile fatty acids (VFAs) as anaerobic digestion (AD) intermediates was investigated at pH 7. Photobacterium phosphoreum T3 was used as an indicator organism. Binary, ternary and mixtures of AD intermediates were designated by letters A (acetic acid + propionic acid), B (acetic acid + butyric acid), C (acetic acid + ethanol), D (propionic acid + butyric acid), E (propionic acid + ethanol), F (butyric acid + ethanol), G (acetic acid + propionic acid + butyric acid), H (acetic acid + propionic acid + ethanol), I (acetic acid + butyric acid+ ethanol), J (propionic acid + butyric acid + ethanol) and K (acetic acid + propionic acid + butyric acid + ethanol) to assess the toxicity through equitoxic mixing ratio method. The IC₅₀ values of acetic acid, propionic acid, butyric acid and ethanol were 9.812, 7.76, 6.717 and 17.33 g/L respectively, displaying toxicity order of: butyric acid > propionic acid > acetic acid > ethanol being additive in nature. The toxic effects of four VFAs could be designated as synergistic and one additive in nature.