Nitric oxide and hydrogen sulfide crosstalk during heavy metal stress in plants

Gases such as ethylene, hydrogen peroxide (H₂O₂), nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H₂S) have been recognized as vital signaling molecules in plants and animals. Of these gasotransmitters, NO and H₂S have recently gained momentum mainly because of their involvement in numerous cellular processes. It is therefore important to study their various attributes including their biosynthetic and signaling pathways. The present review provides an insight into various routes for the biosynthesis of NO and H₂S as well as their signaling role in plant cells under different conditions, more particularly under heavy metal stress. Their beneficial roles in the plant's protection against abiotic and biotic stresses as well as their adverse effects have been addressed. This review describes how H₂S and NO, being very small-sized molecules, can quickly pass through the cell membranes and trigger a multitude of responses to various factors, notably to various stress conditions such as drought, heat, osmotic, heavy metal and multiple biotic stresses. The versatile interactions between H₂S and NO involved in the different molecular pathways have been discussed. In addition to the signaling role of H₂S and NO, their direct role in posttranslational modifications is also considered. The information provided here will be helpful to better understand the multifaceted roles of H₂S and NO in plants, particularly under stress conditions.     

Convenient synthesis of thioamidated peptides and proteins

The unique physicochemical properties of a thioamide bond, which is an ideal isostere of an amide bond, have not been fully exploited because of the tedious synthesis of thionated amino acid building blocks. Here, we report a purification‐free and highly efficient synthesis of thiobenzotriazolides of Fmoc‐protected and orthogonally protected 20 naturally occurring amino acids including asparagine, glutamine, and histidine. The near‐quantitative conversion to the respective thioamidated peptides on solid support demonstrates the robustness of the synthetic route. Furthermore, the unaltered incorporation efficiency of thiobenzotriazolides from their stock solution till 48 h suggests their compatibility toward automated peptide synthesis. Finally, utilizing an optimized cocktail of 2% DBU + 5% piperazine for fast Fmoc‐deprotection, we report the synthesis of a thioamidated Pin1 WW domain and thioamidated GB1 directly on solid support.     

The oxygen isotopic signature of soil‐ and plant‐derived sulphate is controlled by fertilizer type and water source

The oxygen isotope signature of sulphate (δ¹⁸O_sulphate) is increasingly used to study nutritional fluxes and sulphur transformation processes in a variety of natural environments. However, mechanisms controlling the δ¹⁸O_sulphate signature in soil–plant systems are largely unknown. The objective of this study was to determine key factors, which affect δ¹⁸O_sulphate values in soil and plants. The impact of an ¹⁸O‐water isotopic gradient and different types of fertilizers was investigated in a soil incubation study and a radish (Raphanus sativus L.) greenhouse growth experiment. Water provided 31–64% of oxygen atoms in soil sulphate formed via mineralization of organic residues (green and chicken manures) while 49% of oxygen atoms were derived from water during oxidation of elemental sulphur. In contrast, δ¹⁸O_sulphate values of synthetic fertilizer were not affected by soil water. Correlations between soil and plant δ¹⁸O_sulphate values were controlled by water δ¹⁸O values and fertilizer treatments. Additionally, plant δ³⁴S data showed that the sulphate isotopic composition of plants is a function of S assimilation. This study documents the potential of using compound‐specific isotope ratio analysis for investigating and tracing fertilization strategies in agricultural and environmental studies.     

The analog of cGAMP,c-di-AMP,activates STING mediated cell death pathway in estrogen-receptor negative breast cancer cells

Apoptosis - Immune adaptor protein like STING/MITA regulate innate immune response and plays a critical role in inflammation in the tumor microenvironment and regulation of metastasis including...     

Transient cell function disruption by low dose acute exposure of ionizing radiation

Incubation of BMG-1 cells with thallium chloride (201Tl) in the range of diagnostic dose did not show a smooth uptake curve and appeared to have an unsuspected deviation in initial phase. In the present study this unexpected phenomenon was explored, using commonly used radionuclides (viz., 201Tl and 131I). Comparison was made with technetium-99m pertechnetate (99mTcO4(-)) and technetium-99m labeled methoxyisobutylisonitrile (99mTc-MIBI) that are known to show conventional 2 phase graph representing inflow and outflow segments. Serial in vitro, ex-vivo and in vivo gamma scintigraphy as well as NMR spectroscopy experiments were conducted to corroborate the results. BMG-1 cells demonstrated a four-phase uptake pattern with 201Tl as compared to a conventional biphasic pattern with 99mTc-MIBI. Flow cytometry data however did not reveal any 201Tl induced cell injury. Further, mice tissue extracts injected with 201Tl also showed a transient depression in its uptake. Scintigraphy experiments in rabbits administered with diagnostic dose of 201Tl and 131I confirmed the in vitro and ex vivo findings. Further, proton NMR spectroscopy showed decrease in the level of choline at 3 h and 24 h in 201Tl treated animals as compared to control. Phosphoethanolamine peak firstly decreased at 3 h but reached normal level at 24 h time point. No significant change was observed in the level of betaine. This transient reduction in internalization of 201Tl and 131I may represent a hitherto unknown acute effect of low dose radiation, i.e., transient depression in Na+-K+ ATPase pump activity without any apparent evidence of cell damage, representing a transient cell membrane dysfunction. The phenomenon may present a mechanistical explanation of 'thyroid stunning' at cellular level and suggest that it may be more universal in nature than suspected till now.     

An N-terminal polybasic domain and cell surface localization are required for mutant prion protein toxicity

There is evidence that alterations in the normal physiological activity of PrP(C) contribute to prion-induced neurotoxicity. This mechanism has been difficult to investigate, however, because the normal function of PrP(C) has remained obscure, and there are no assays available to measure it. We recently reported that cells expressing PrP deleted for residues 105-125 exhibit spontaneous ionic currents and hypersensitivity to certain classes of cationic drugs. Here, we utilize cell culture assays based on these two phenomena to test how changes in PrP sequence and/or cellular localization affect the functional activity of the protein. We report that the toxic activity of Δ105-125 PrP requires localization to the plasma membrane and depends on the presence of a polybasic amino acid segment at the N terminus of PrP. Several different deletions spanning the central region as well as three disease-associated point mutations also confer toxic activity on PrP. The sequence domains identified in our study are also critical for PrP(Sc) formation, suggesting that common structural features may govern both the functional activity of PrP(C) and its conversion to PrP(Sc).     

Trafficking of α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid Receptor (AMPA) Receptor Subunit GluA2 from the Endoplasmic Reticulum Is Stimulated by a Complex Containing Ca2+/Calmodulin-activated Kinase II (CaMKII) and PICK1 Protein and by Release of Ca2+ from Internal Stores

The GluA2 subunit of the AMPA receptor (AMPAR) dominantly blocks AMPAR Ca²⁺ permeability, and its trafficking to the synapse regulates AMPAR-dependent synapse Ca²⁺ permeability. Here we show that GluA2 trafficking from the endoplasmic reticulum (ER) to the plasma membrane of cultured hippocampal neurons requires Ca²⁺ release from internal stores, the activity of Ca²⁺/calmodulin activated kinase II (CaMKII), and GluA2 interaction with the PDZ protein, PICK1. We show that upon Ca²⁺ release from the ER via the IP3 and ryanodine receptors, CaMKII that is activated enters a complex that contains PICK1, dependent upon the PICK1 BAR (Bin-amphiphysin-Rvs) domain, and that interacts with the GluA2 C-terminal domain and stimulates GluA2 ER exit and surface trafficking. This study reveals a novel mechanism of regulation of trafficking of GluA2-containing receptors to the surface under the control of intracellular Ca²⁺ dynamics and CaMKII activity.     

Grimontia indica AK16T,sp. nov., Isolated from a Seawater Sample Reports the Presence of Pathogenic Genes Similar to Vibrio Genus

Grimontia indica strain AK16^T sp. nov. is the type strain of G. indica sp. nov. a new species within the genus Grimontia. This strain, whose genome is described here, was isolated from seawater sample collected from southeast coast of Palk Bay, India. G. indica AK16^T is a Gram-negative, facultative aerobic rod shaped bacterium. There are only two other strains in the genus Grimontia one of which, Grimontia hollisae CIP 101886^T, is a reported human pathogen isolated from human stool sample while the other, ‘Grimontia marina IMCC5001^T’, was isolated from a seawater sample. As compared to the pathogenic strain Grimontia hollisae CIP 101886^T, the strain AK16^T lacks some genes for pathogenesis like the accessory colonization factors AcfA and AcfD, which are required for the colonization of the bacterium in the host body. While it carries some pathogenesis genes like OmpU, which are related to pathogenesis of Vibrio strains. This suggests that the life cycle of AK16^T may include some pathogenic interactions with marine animal(s), or it may be an opportunistic pathogen. Study of the Grimontia genus is important because of the severe pathogenic traits exhibited by a member of the genus with only three species reported in total. The study will provide some vital information which may be useful in future clinical studies on the genus.     

Profiling gene expression using onto-express

Gene expression profiles obtained through microarray or data mining analyses often exist as vast data strings. To interpret the biology of these genetic profiles, investigators must analyze this data in the context of other information such as the biological, biochemical, or molecular function of the translated proteins. This is particularly challenging for a human analyst because large quantities of less than relevant data often bury such information. To address this need we implemented an automated routine, called Onto-Express (http://vortex.cs.wayne.edu:8080), to systematically translate genetic fingerprints into functional profiles. Using strings of accession or cluster identification numbers, Onto-Express searches the public databases and returns tables that correlate expression profiles with the cytogenetic locations, biochemical and molecular functions, biological processes, cellular components, and cellular roles of the translated proteins. The profiles created by Onto-Express fundamentally increase the value of gene expression analyses by facilitating the translation of quantitative value sets to records that contain biological implications.     

Beyond knockout rats: New insights into finer genome manipulation in rats

The ability to “knockout” specific genes in mice via embryonic stem (ES) cell-based gene-targeting technology has significantly enriched our understanding of gene function in normal and disease phenotypes. Improvements on this original strategy have been developed to enable the manipulation of genomes in a more sophisticated fashion with unprecedented precision. The rat is the model of choice in many areas of scientific investigation despite the lack of rat genetic toolboxes. Most recent advances of zinc finger nucleases (ZFNs) and rat ES cells are diminishing the gap between rat and mouse with respect to reverse genetic approaches. Importantly, the establishment of rat ES cell-based gene targeting technology, in combination with the unique advantages of using rats, provides new, exciting opportunities to create animal models that mimic human diseases more faithfully. We hereby report our recent results concerning finer genetic modifications in the rat, and propose their potential applications in addressing biological questions.Key words: genetic manipulation, gene targeting, conditional knockout, transgenic animal, rat model, p53 knockout rat, embryonic stem cells