Phytoremediation of 137Cs: factors and consequences in the environment

Radionuclide contamination is a concerning threat due to unexpected nuclear disasters and authorized discharge of radioactive elements, both in the past and in present times. Use of atomic power for energy generation is associated with unresolved issues concerning storage of residues and contaminants. For example, the nuclear accidents in Chernobyl 1986 and Fukushima 2011 resulted in considerable deposition of cesium (Cs) in soil, along with other radionuclides. Among Cs radioactive variants, the anthropogenic radioisotope ¹³⁷Cs (t_½?=?30.16 years) is of serious environmental concern, owing to its rapid incorporation into biological systems and emission of β and γ radiation during the decaying process. To remediate contaminated areas, mostly conventional techniques are applied that are not eco-friendly. Hence, an alternative green technology, i.e., phytoremediation, should in future be considered and implemented. This sustainable technology generates limited secondary waste and its objectives are to utilize hyper-accumulating plants to extract, stabilize, degrade, and filter the radionuclides. The review highlights plant mechanisms for up-taking radionuclides and influences of different environmental factors involved in the process, while considering its long-term effects.

     

Suppression of reactive oxygen species production enhances neuronal survival in vitro and in vivo in the anoxia-tolerant turtle Trachemys scripta

Hypoxia-ischemia with reperfusion is known to cause reactive oxygen species-related damage in mammalian systems, yet, the anoxia tolerant freshwater turtle is able to survive repeated bouts of anoxia/reoxygenation without apparent damage. Although the physiology of anoxia tolerance has been much studied, the adaptations that permit survival of reoxygenation stress have been largely ignored. In this study, we examine ROS production in the turtle striatum and in primary neuronal cultures, and examine the effects of adenosine (AD) on cell survival and ROS. Hydroxyl radical formation was measured by the conversion of salicylate to 2,3-dihydroxybenzoic acid (2,3-DHBA) using microdialysis; reoxygenation after 1 or 4 h anoxia did not result in increased ROS production compared with basal normoxic levels, nor did H₂O₂ increase after anoxia/reoxygenation in neuronally enriched cell cultures. Blockade of AD receptors increased both ROS production and cell death in vitro , while AD agonists decreased cell death and ROS. As turtle neurons proved surprisingly susceptible to externally imposed ROS stress (H₂O₂), we propose that the suppression of ROS formation, coupled to high antioxidant levels, is necessary for reoxygenation survival. As an evolutionarily selected adaptation, the ability to suppress ROS formation could prove an interesting path to investigate new therapeutic targets in mammals.     

Modularized study of human calcium signalling pathway

Signalling pathways are complex biochemical networks responsible for regulation of numerous cellular functions. These networks function by serial and successive interactions among a large number of vital biomolecules and chemical compounds. For deciphering and analysing the underlying mechanism of such networks,a modularized study is quite helpful. Here we propose an algorithm for modularization of calcium signalling pathway of H. sapiens .The idea that "a node whose function is dependent on maximum number of other nodes tends to be the center of a sub network" is used to divide a large signalling network into smaller sub networks. Inclusion of node(s) into sub networks(s) is dependent on the outdegree of the node(s). Here outdegree of a node refers to the number of relations of the considered node lying outside the constructed sub network. Node(s) having more than c relations lying outside the expanding sub network have to be excluded from it. Here c is a specified variable based on user preference, which is finally fixed during adjustments of created sub networks, so that certain biological significance can be conferred on them.     

New high fidelity polymerases from Thermococcus species

Two DNA polymerase genes have been isolated from Thermococcus strains, Thermococcus zilligii from New Zealand, and the other, Thermococcus 'GT', a fast-growing strain isolated from the Galapagos trench. Both genes were isolated by genomic walking PCR, a technique that does not require expression of the gene product. Phylogenetic analysis of SSU rDNA showed that the two strains were not closely related, as confirmed by an examination of the DNA polymerase sequences. Inteinless versions of each gene were generated by overlap-extension PCR and transferred into plasmid expression vectors. The proteins were produced in an Escherichia coli strain with additional copies of tRNAs corresponding to rarely used codons and purified by standard chromatographic procedures. Both enzymes were able to support PCR, but the Thermococcus 'GT' polymerase required higher concentrations of template than the enzyme from T. zilligii. Both enzymes showed 3' to 5' exonuclease activity, which was abolished in the case of T. zilligii by mutating the aspartic acid at position 141 and the glutamic acid at position 143 to alanine. Both enzymes showed a significant increase in fidelity of replication compared to the family A Thermus aquaticus DNA polymerase, in agreement with other results reported for family B polymerases with proof-reading ability.     

High frequency plantlet regeneration from cotyledonary node cultures of <Emphasis Type="Italic">Aegle marmelos</Emphasis> (L.) Corr.

High frequency plantlet regeneration was achieved in cotyledonary nodes of Aegle marmelos. Cotyledonary nodes from 1 mo. old in vitro grown seedlings of A. marmelos were cultured on Murashige and Skoog (MS) medium supplemented with benzyl adenine (BA) (0–8.8 μM), kinetin (KIN) (0–9.4 μM), and indole-3-acetic acid (IAA) (0–1.14 μM) either alone or in combinations. The highest regenerative response was observed on medium containing 6.6 μM BA + 1.14 μM IAA where approximately 86.6% of the cultures responded with an average shoot numbers of 487.5 per explant in 7-wk time. Cultures maintained on KIN-supplemented medium showed very poor response. In vitro responded shoots were transferred to root induction medium consisting of half-strength MS supplemented with auxins IAA, indole-3-butyric acid (IBA), or α-naphthalene acetic acid (NAA). Rooting was best in medium supplemented with 14.7 μM IBA. Rooted plantlets were acclimatized and transferred to the field with 80% survival rate.     

Indirect Immunodetection of Fungal Fragments by Field Emission Scanning Electron Microscopy

Submicronic fungal fragments have been observed in in vitro aerosolization experiments. The occurrence of these particles has therefore been suggested to contribute to respiratory health problems observed in mold-contaminated indoor environments. However, the role of submicronic fragments in exacerbating adverse health effects has remained unclear due to limitations associated with detection methods. In the present study, we report the development of an indirect immunodetection assay that utilizes chicken polyclonal antibodies developed against spores from Aspergillus versicolor and high-resolution field emission scanning electron microscopy (FESEM). Immunolabeling was performed with A. versicolor fragments immobilized and fixed onto poly-l-lysine-coated polycarbonate filters. Ninety percent of submicronic fragments and 1- to 2-μm fragments, compared to 100% of >2-μm fragments generated from pure freeze-dried mycelial fragments of A. versicolor, were positively labeled. In proof-of-concept experiments, air samples collected from moldy indoor environments were evaluated using the immunolabeling technique. Our results indicated that 13% of the total collected particles were derived from fungi. This fraction comprises 79% of the fragments that were detected by immunolabeling and 21% of the spore particles that were morphologically identified. The methods reported in this study enable the enumeration of fungal particles, including submicronic fragments, in a complex heterogeneous environmental sample.     

A computational-experimental approach identifies mutations that enhance surface expression of an oseltamivir-resistant influenza neuraminidase

The His274→Tyr (H274Y) oseltamivir (Tamiflu) resistance mutation causes a substantial decrease in the total levels of surface-expressed neuraminidase protein and activity in early isolates of human seasonal H1N1 influenza, and in the swine-origin pandemic H1N1. In seasonal H1N1, H274Y only became widespread after the occurrence of secondary mutations that counteracted this decrease. H274Y is currently rare in pandemic H1N1, and it remains unclear whether secondary mutations exist that might similarly counteract the decreased neuraminidase surface expression associated with this resistance mutation in pandemic H1N1. Here we investigate the possibility of predicting such secondary mutations. We first test the ability of several computational approaches to retrospectively identify the secondary mutations that enhanced levels of surface-expressed neuraminidase protein and activity in seasonal H1N1 shortly before the emergence of oseltamivir resistance. We then use the most successful computational approach to predict a set of candidate secondary mutations to the pandemic H1N1 neuraminidase. We experimentally screen these mutations, and find that several of them do indeed partially counteract the decrease in neuraminidase surface expression caused by H274Y. Two of the secondary mutations together restore surface-expressed neuraminidase activity to wildtype levels, and also eliminate the very slight decrease in viral growth in tissue-culture caused by H274Y. Our work therefore demonstrates a combined computational-experimental approach for identifying mutations that enhance neuraminidase surface expression, and describes several specific mutations with the potential to be of relevance to the spread of oseltamivir resistance in pandemic H1N1.     

Nonsterile immunity to cryptosporidiosis in infants is associated with mucosal IgA against the sporozoite and protection from malnutrition

We conducted a longitudinal study of cryptosporidiosis from birth to three years of age in an urban slum of Dhaka Bangladesh. Fecal DNA was extracted from monthly surveillance samples and diarrheal stool samples collected from 392 infants from birth to three years. A pan-Cryptosporidium qPCR assay was used to identify sub-clinical and symptomatic cryptosporidiosis. Anthropometric measurements were collected quarterly to assess child nutritional status. 31% (121/392) of children experienced a single and 57% (222/392) multiple infections with Cryptosporidium. Repeat infections had a lower burden of parasites in the stool (Cq slope = -1.85; p<0.0001) and were more likely to be sub-clinical (Chi square test for trend; p = 0.01). Repeat infections were associated with the development of growth faltering (Pearson correlation = -0.18; p = 0.0004). High levels of fecal IgA antibodies against the Cryptosporidium Cp23 sporozoite protein at one year of life were associated with a delay in reinfection and amelioration of growth faltering through three years of life (HAZ IgA high responders -1.323 ± 0.932 versus HAZ -1.731 ± 0.984 p = 0.0001). We concluded that nonsterile immunity to cryptosporidiosis in young children was associated with high levels of mucosal IgA anti-Cp23 and protection from diarrhea and growth faltering.Trial Registration: {"type":"clinical-trial","attrs":{"text":"NCT02764918","term_id":"NCT02764918"}}NCT02764918.