Heavy metal pollution in aquatic ecosystems and its phytoremediation using wetland plants: an ecosustainable approach

This review addresses the global problem of heavymetal pollution originating from increased industrialization and urbanization and its amelioration by using wetland plants both in a microcosm as well as natural/field condition. Heavymetal contamination in aquatic ecosystems due to discharge of industrial effluents may pose a serious threat to human health. Alkaline precipitation, ion exchange columns, electrochemical removal, filtration, and membrane technologies are the currently available technologies for heavy metal removal. These conventional technologies are not economical and may produce adverse impacts on aquatic ecosystems. Phytoremediation of metals is a cost-effective "green" technology based on the use of specially selected metal-accumulating plants to remove toxic metals from soils and water. Wetland plants are important tools for heavy metal removal. The Ramsar convention, one of the earlier modern global conservation treaties, was adopted at Ramsar, Iran, in 1971 and became effective in 1975. This convention emphasized the wise use of wetlands and their resources. This review mentions salient features of wetland ecosystems, their vegetation component, and the pros and cons involved in heavy metal removal. Wetland plants are preferred over other bio-agents due to their low cost, frequent abundance in aquatic ecosystems, and easy handling. The extensive rhizosphere of wetland plants provides an enriched culture zone for the microbes involved in degradation. The wetland sediment zone provides reducing conditions that are conducive to the metal removal pathway. Constructed wetlands proved to be effective for the abatement of heavymetal pollution from acid mine drainage; landfill leachate; thermal power; and municipal, agricultural, refinery, and chlor-alkali effluent. the physicochemical properties of wetlands provide many positive attributes for remediating heavy metals. Typha, Phragmites, Eichhornia, Azolla, Lemna, and other aquatic macrophytes are some of the potent wetland plants for heavy metal removal. Biomass disposal problem and seasonal growth of aquatic macrophytes are some limitations in the transfer of phytoremediation technology from the laboratory to the field. However, the disposed biomass of macrophytes may be used for various fruitful applications. An ecosustainable model has been developed through the author's various works, which may ameliorate some of the limitations. The creation of more areas for phytoremediation may also aid in wetlands conservation. Genetic engineering and biodiversity prospecting of endangered wetland plants are important future prospects in this regard.     

Simple sequence repeat (SSR) markers linked to E1, E3, E4, and E7 maturity genes in soybean.

Soybean near isogenic lines (NILs), contrasting for maturity and photoperiod sensitivity loci, were genotyped with approximately 430 mapped simple sequence repeats (SSRs), also known as microsatellite markers. By analysis of allele distributions across the NILs, it was possible to confirm the map location of the Dt1 indeterminate growth locus, to refine the SSR mapping of the T tawny pubescence locus, to map E1 and E3 maturity loci with molecular markers, and to map the E4 and E7 maturity loci for the first time. Molecular markers flanking these loci are now available for marker-assisted breeding for these traits. Analysis of map locations identified a putative homologous relationship among four chromosomal regions; one in the middle of linkage group (LG) C2 carrying E1 and E7, one on LG I carrying E4, one at the top of LG C2, at which there is a reproductive period quantitative trait locus (QTL), and the fourth on LG B1. Other evidence suggests that homology also exists between the E1 + E7 region on LG C2 and a region on LG L linked to a pod maturity QTL. Homology relationships predict possible locations in the soybean genome of additional maturity loci, as well as which maturity loci may share a common evolutionary origin and similar mechanism(s) of action.     

Acetoxy drug: protein transacetylase of buffalo liver—characterization and mass spectrometry of the acetylated protein product

The purification and characterization of the buffalo liver microsomal transacetylase (TAase) catalyzing the transfer of acetyl groups from a model acetoxy drug: 7,8-diacetoxy-4-methylcoumarin (DAMC) to GST3–3 has been described here. The enzyme was routinely assayed using DAMC and cytosolic GST as the substrates and was partially purified from microsomes of the buffalo liver. The enzyme was found to have approximate molecular of weight 65 kDa. The action of TAase and DAMC on liver cytosolic GST resulted in the formation of monoacetoxymonohydroxy-4-methylcoumarin (MAMHC) and 7,8-dihydroxy-4-methylcoumarin (DHMC), although the former was the major metabolite. The buffalo liver microsomal TAase exhibited hyperbolic kinetics and yielded K_m (1667 μM) and V_max (192 units) when the concentration of DAMC was varied keeping the concentration of GST constant. After having characterized the nature of the substrates and a product of the TAase-catalyzed reaction, we set out to identify the acetylated protein which is another product of the reaction. GST3–3 was used as a model protein substrate for the action of TAase using DAMC as the acetyl donor. The subunit of control and modified GST3–3 were separated by SDS-polyacrylamide gel electrophoresis (PAGE) and digested with trypsin. The tryptic peptides were extracted from the gel pieces and analyzed by matrix assisted laser desorption/ionization–time of flight–mass spectrometry (MALDI-TOFMS). The data search for calibrated and labeled mass peaks of peptides was performed on the Matrix Science Server using the search engine Mascot. The peptide maps so obtained covered 97% of the GST3–3 sequence. On comparison of MALDI peptide maps of modified and control GST, seven new peaks were recognized corresponding to the potentially acetylated peptides in peptide map. The mass value of each of them was 42 Da higher than the theoretical mass of a non-modified GST3–3 tryptic peptide, strongly suggesting acetylation. By examining the fragmentation patterns and by comparing experimental and predicted values for MS/MS daughter ions, the identity of the seven acetylated GST tryptic peptides could be confirmed by the application of LC/MS/MS. In the modified GST, N-terminal proline and six lysines (Lys₅₁, Lys₈₂, Lys₁₂₃, Lsy₁₈₁, Lys₁₉₁ and Lys₂₁₀) were found to be acetylated. The structure of acetylated GST revealed that the lysines that underwent acetylation were peripheral in positions.     

Biotechnological potential of Microcystis sp. in Cu, Zn and Cd biosorption from single and multimetallic systems

This paper provides information on biosorption of Cu, Zn and Cd by Microcystis sp. in single, bi and trimetallic combination. Highest biosorption of Cu followed by Zn and Cd in single as well as in mixtures containing two or three metals was noticed. The order of inhibition of Cu, Zn and Cd biosorption in bi and trimetallic combinations was suggestive of screening or competition for the binding sites on the cell surface. This observation was reconfirmed by Freundlich adsorption isotherm. K_f values were maximum for Cu (K_f=45.18), followed by Zn (K_f=16.71), and Cd (K_f=15.63) in single metallic system. The K_f values for each test metal was reduced in solution containing more than one metal. Further, the reduction in biosorption of each metal ion due to presence of other metal ion was of greater magnitude at relatively higher concentrations of interfering metal ion. The biosorption of Cu at saturation was less affected when secondary metal (Cd or Zn) was added in the medium. Above results suggest that Microcystis holds great potential for metal biosorption from mixture.     

Multimodal regulation of myosin VI ensemble transport by cargo adaptor protein GIPC

A range of cargo adaptor proteins are known to recruit cytoskeletal motors to distinct subcellular compartments. However, the structural impact of cargo recruitment on motor function is poorly understood. Here, we dissect the multimodal regulation of myosin VI activity through the cargo adaptor GAIP-interacting protein, C terminus (GIPC), whose overexpression with this motor in cancer enhances cell migration. Using a range of biophysical techniques, including motility assays, FRET-based conformational sensors, optical trapping, and DNA origami–based cargo scaffolds to probe the individual and ensemble properties of GIPC–myosin VI motility, we report that the GIPC myosin-interacting region (MIR) releases an autoinhibitory interaction within myosin VI. We show that the resulting conformational changes in the myosin lever arm, including the proximal tail domain, increase the flexibility of the adaptor–motor linkage, and that increased flexibility correlates with faster actomyosin association and dissociation rates. Taken together, the GIPC MIR–myosin VI interaction stimulates a twofold to threefold increase in ensemble cargo speed. Furthermore, the GIPC MIR–myosin VI ensembles yield similar cargo run lengths as forced processive myosin VI dimers. We conclude that the emergent behavior from these individual aspects of myosin regulation is the fast, processive, and smooth cargo transport on cellular actin networks. Our study delineates the multimodal regulation of myosin VI by the cargo adaptor GIPC, while highlighting linkage flexibility as a novel biophysical mechanism for modulating cellular cargo motility.     

Biogenic synthesis of metal nanoparticles from actinomycetes: biomedical applications and cytotoxicity

Biogenic synthesis of metal nanoparticles has been well proved by using bacteria, fungi, algae, actinomycetes, plants, etc. Among the different microorganisms used for the synthesis of metal nanoparticles, actinomycetes are less known. Although, there are reports, which have shown that actinomycetes are efficient candidates for the production of metal nanoparticles both intracellularly and extracellularly. The nanoparticles synthesized by the members of actinomycetes present good polydispersity and stability and possess significant biocidal activities against various pathogens. The present review focuses on biological synthesis of metal nanoparticles and their application in medicine. In addition, the toxicity of these biogenic metal nanoparticles to human beings and environment has also been discussed.     

Extraction of rIL-2 inclusion bodies from Escherichia coli using cross-flow filtration

A cross-flow membrane filtration process was developed for the recovery of rIL-2 inclusion bodies from homogenized Escherichia coli. The membrane extraction process was comprised of a two-step diafiltration followed by an extraction with 7 M GuHCl and a 40-fold dilution of the solubilized inclusion bodies into 0.01 M Tris-HCl, 0.035 M NaCl, pH 7.9. The first diafiltration was with a 0.03 M Tris-HCl, 5 mM ethylenediaminetetraacetic acid (EDTA), pH 8, followed by a diafiltration with 1.75 M GuHCl. All of the insoluble rIL-2 was retained behind the membrane, whereas a GuHCl wash solubilized approximately 15% of the rIL-2. The membrane process increased the yield of rIL-2 in the diluted extract by threefold as compared to a similar centrifuge process with a significant increase in purity as determined by reverse-phase high-performance liquid chromatography (HPLC). (c) 1994 John Wiley & Sons, Inc.     

Antioxidant and nitric oxide synthase activation properties of Ganoderma applanatum

In vitro evaluation of antioxidant activities of Ganoderma applanatum showed significant inhibition of lipid peroxidation, and potent hydroxyl radical scavenging activity when compared with standard drug catechin. IC50 values of crude, boiled and ethanolic extracts of G. applanatum were 604.8, 624 and 267 microg/ml, respectively in case of hydroxyl radical scavenging activity, and 441, 520.5 and 166.16 microg/ml, respectively in case of lipid peroxidation. Furthermore, crude, boiled and ethanolic extracts also increased significantly nitric oxide production (156.67, 121.88 and 742 pmole/mg dry wt/hr, respectively) over the control. The results of present investigation revealed that G. applanatum have potential therapeutic use.     

Endophytic actinobacteria of medicinal plants: diversity and bioactivity

Endophytes are the microorganisms that exist inside the plant tissues without having any negative impact on the host plant. Medicinal plants constitute the huge diversity of endophytic actinobacteria of economical importance. These microbes have huge potential to synthesis of numerous novel compounds that can be exploited in pharmaceutical, agricultural and other industries. It is of prime importance to focus the present research on practical utilization of this microbial group in order to find out the solutions to the problems related to health, environment and agriculture. An extensive characterization of diverse population of endophytic actinobacteria associated with medicinal plants can provide a greater insight into the plant-endophyte interactions and evolution of mutualism. In the present review, we have discussed the diversity of endophytic actinobacteria of from medicinal plants their multiple bioactivities.