Chronic renal failure (CRF), in the main agricultural region under reservoir based cascade irrigation in Sri Lanka has reached crisis proportion. Over 5,000 patients in the region are under treatment for CRF. The objective of this study is to establish the etiology of the CRF. Concentrations of nine heavy metals were determined in sediments, soils of reservoir peripheries, water and Nelumbo nucifera (lotus) grown in five major reservoirs that supply irrigation water. All five reservoirs carried higher levels of dissolved cadmium (Cd), iron (Fe) and lead (Pb). Dissolved Cd in reservoir water ranged from 0.03 to 0.06 mg/l. Sediment Cd concentration was 1.78-2.45 mg/kg. No arsenic (As) was detected. Cd content in lotus rhizomes was 253.82 mg/kg. The Provisional Tolerable Weekly Intake (PTWI) of Cd based on extreme exposure of rice is 8.702-15.927 microg/kg body weight (BW) for different age groups, 5-50 years. The PTWI of Cd due to extreme exposure of fish is 6.773-12.469 microg/kg BW. The PTWI on a rice staple with fish is 15.475-28.396 microg/kg BW. The mean urinary cadmium (UCd) concentration in CRF patients of age group 40-60 years was 7.58 microg Cd/g creatinine and in asymptomatic persons UCd was 11.62 microg Cd/g creatinine, indicating a chronic exposure to Cd. The possible source of Cd in reservoir sediments and water is Cd-contaminated agrochemicals. The CRF prevalent in north central Sri Lanka is a result of chronic dietary intake of Cd, supported by high natural levels of fluoride in drinking water, coupled with neglecting of routine de-silting of reservoirs for the past 20 years.
BackgroundThe transcriptional regulatory network involved in low temperature response leading to acclimation has been established in Arabidopsis. In japonica rice, which can only withstand transient exposure to milder cold stress (10°C), an oxidative-mediated network has been proposed to play a key role in configuring early responses and short-term defenses. The components, hierarchical organization and physiological consequences of this network were further dissected by a systems-level approach.ResultsRegulatory clusters responding directly to oxidative signals were prominent during the initial 6 to 12 hours at 10°C. Early events mirrored a typical oxidative response based on striking similarities of the transcriptome to disease, elicitor and wounding induced processes. Targets of oxidative-mediated mechanisms are likely regulated by several classes of bZIP factors acting on as1/ocs/TGA-like element enriched clusters, ERF factors acting on GCC-box/JAre-like element enriched clusters and R2R3-MYB factors acting on MYB2-like element enriched clusters.Temporal induction of several H2O2-induced bZIP, ERF and MYB genes coincided with the transient H2O2 spikes within the initial 6 to 12 hours. Oxidative-independent responses involve DREB/CBF, RAP2 and RAV1 factors acting on DRE/CRT/rav1-like enriched clusters and bZIP factors acting on ABRE-like enriched clusters. Oxidative-mediated clusters were activated earlier than ABA-mediated clusters.ConclusionGenome-wide, physiological and whole-plant level analyses established a holistic view of chilling stress response mechanism of japonica rice. Early response regulatory network triggered by oxidative signals is critical for prolonged survival under sub-optimal temperature. Integration of stress and developmental responses leads to modulated growth and vigor maintenance contributing to a delay of plastic injuries.
The R2R3-type OsMyb4 transcription factor of rice has been shown to play a role in the regulation of osmotic adjustment in heterologous overexpression studies. However, the exact composition and organization of its underlying transcriptional network has not been established to be a robust tool for stress tolerance enhancement by regulon engineering. OsMyb4 network was dissected based on commonalities between the global chilling stress transcriptome and the transcriptome configured by OsMyb4 overexpression. OsMyb4 controls a hierarchical network comprised of several regulatory sub-clusters associated with cellular defense and rescue, metabolism and development. It regulates target genes either directly or indirectly through intermediary MYB, ERF, bZIP, NAC, ARF and CCAAT-HAP transcription factors. Regulatory sub-clusters have different combinations of MYB-like, GCC-box-like, ERD1-box-like, ABRE-like, G-box-like, as1/ocs/TGA-like, AuxRE-like, gibberellic acid response element (GARE)-like and JAre-like cis-elements. Colddependent network activity enhanced cellular antioxidant capacity through radical scavenging mechanisms and increased activities of phenylpropanoid and isoprenoid metabolic processes involving various abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), ethylene and reactive oxygen species (ROS) responsive genes. OsMyb4 network is independent of drought response element binding protein/C-repeat binding factor (DREB/CBF) and its sub-regulons operate with possible co-regulators including nuclear factor-Y. Because of its upstream position in the network hierarchy, OsMyb4 functions quantitatively and pleiotrophically. Supra-optimal expression causes misexpression of alternative targets with costly trade-offs to panicle development.
Endoplasmic reticulum (ER) stress due to biotic or abiotic stress activates the unfolded protein response (UPR) to restore ER homeostasis. The UPR relies on multiple ER-to-nucleus signaling factors which mainly induce the expression of cytoprotective ER-chaperones. The inositol requiring enzyme (IRE1) along with its splicing target, bZIP60, restrict potyvirus, and potexvirus accumulation. Until now, the involvement of the alternative UPR pathways and the role of UPR to limit virus accumulation have remained elusive. Here, we used the Plantago asiatica mosaic virus (PlAMV) and the Turnip mosaic virus (TuMV) to demonstrate that the potexvirus triple gene block 3 (TGB3) protein and the potyvirus 6K2 protein activate the bZIP17, bZIP28, bZIP60, BAG7, NAC089 and NAC103 signaling in Arabidopsis thaliana. Using the corresponding knockout mutant lines, we demonstrated that these factors differentially restrict local and systemic virus accumulation. We show that bZIP17, bZIP60, BAG7, and NAC089 are factors in PlAMV infection, whereas bZIP28 and bZIP60 are factors in TuMV infection. TGB3 and 6K2 transient expression in leave reveal that these alternative pathways induce BiPs expression. Finally, using dithiothreitol (DTT) and tauroursodeoxycholic acid (TUDCA) treatment, we demonstrated that the protein folding capacity significantly influences PlAMV accumulation. Together, these results indicate that multiple ER-to-nucleus signaling pathways are activated during virus infection and restrict virus accumulation through increasing protein folding capacity.
Rose rosette virus (RRV) is a negative-sense RNA virus with a seven-segmented genome that is enclosed by a double membrane. We constructed an unconventional minireplicon system encoding the antigenomic (ag)RNA1 (encoding the viral RNA-dependent RNA polymerase [RdRp]), agRNA3 (encoding the nucleocapsid protein [N]), and a modified agRNA5 containing the coding sequence for the iLOV protein in place of the P5 open reading frame (R5-iLOV). iLOV expression from the R5-iLOV template was amplified by activities of the RdRp and N proteins in Nicotiana benthamiana leaves. A mutation was introduced into the RdRp catalytic domain and iLOV expression was eliminated, indicating RNA1-encoded polymerase activity drives iLOV expression from the R5-iLOV template. Fluorescence from the replicon was highest at 3 days postinoculation (dpi) and declined at 7 and 13 dpi. Addition of the tomato bushy stunt virus (TBSV) P19 silencing-suppressor protein prolonged expression until 7 dpi. A full-length infectious clone system was constructed of seven binary plasmids encoding each of the seven genome segments. Agro-delivery of constructs encoding RRV RNAs 1 through 4 or RNAs 1 through 7 to N. benthamiana plants produced systemic infection. Finally, agro-delivery of the full-length RRV infectious clone including all segments produced systemic infection within 60 dpi. This advance opens new opportunities for studying RRV infection biology. [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .
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