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Rice is vital for food security. Due to its tropical origin, rice suffers from cold temperatures that affect its entire life cycle. Key genes have been identified involved in cold tolerance. WRKYs are generally downstream of the MAPK cascade and can act together with VQ proteins to regulate stress-responsive genes. Chilling treatment was applied at germination to two rice genotypes (tolerant and sensitive). Shoots at S3 stage were collected for RNA-seq to identify OsWRKY, OsMAPKs and OsVQs expression. Relationships among MAPKs, WRKYs and VQs were predicted through correlation analysis. OsWRKY transcriptional regulation was predicted by in silico analysis of cis-regulatory elements. A total of 39 OsWRKYs were differentially expressed. OsWRKY21, OsWRK24 and OsWRKY69 are potential positive regulators, while OsWRKY10, OsWRK47, OsWRKY62, OsWRKY72 and OsWRKY77 are potential negative regulators, of chilling tolerance. 12 OsMAPKs were differentially expressed. OsMAPKs were downregulated and negatively correlated with the upregulated OsWRKYs in the tolerant genotype. 19 OsVQs were differentially expressed, three and six OsVQs were positively correlated with OsWRKYs in the tolerant and sensitive genotypes, respectively. Seven differentially expressed OsWRKYs have cold-responsive elements in their promoters and five upregulated OsWRKYs in the tolerant genotype contained the W-box motif. Chilling causes changes in OsWRKY, OsMAPK and OsVQ gene expression at germination. OsWRKYs may not act downstream of the MAPK cascade to coordinate chilling tolerance, but OsWRKYs may act with VQs to regulate chilling tolerance. Candidate OsWRKYs are correlated and have a W-box in the promoter, suggesting an auto-regulation mechanism.

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Chlorothalonil (CLT) is a broad spectrum, and non-systemic fungicide applied in foliar structures to prevent and treat pathogens. This compound reaches to aquatic environments and affects the biota. In this context, the main goal of this study was to assess the effects of CLT at biochemical, tissular, and individual levels of biological organization using the invasive bivalve Corbicula largillierti as a bioindicator species. Clams were exposed to different sublethal concentrations (0, 10, 20 and 50 µg. L-1 CLT) for 96 h. At biochemical level, the enzymatic activity (Glutathione-s-Transferase, Catalase, Acetyl-, Butiryl- and Carboxyl-esterases) and lipid peroxidation were measured in gills and the visceral mass. Also, the digestive gland morphometry through quantitative histological indexes was registered at the tissular level. Finally, filtering activity and burial behavior at the individual level were measured. At the highest CLT concentration, the most significant changes were observed in enzymatic activity (except for butyrylcholinesterase), lipid peroxidation and in digestive gland morphometry. It was also registered increases of the filtering activity and the latency time to burial. Most of the biomarkers assessed showed significant responses under CLT exposure. Therefore, taking into account that C. largillierti was affected by CLT, it can be expected that other species could be in a potential risk if this fungicide is present in freshwater systems.

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Iron (Fe) is an essential microelement for all living organisms playing important roles in several metabolic reactions. Rice (Oryza sativa L.) is commonly cultivated in paddy fields, where Fe goes through a reduction reaction from Fe3+ to Fe2+. Since Fe2+ is more soluble, it can reach toxic levels inside plant cells, constituting an important target for studies. Here we aimed to verify morphological changes of different rice genotypes focusing on deciphering the underlying molecular network induced upon Fe excess treatments with special emphasis on the role of four WRKY transcription factors. The transcriptional response peak of these WRKY transcription factors in rice seedlings occurs at 4 days of exposition to iron excess. OsWRKY55-like, OsWRKY46, OsWRKY64, and OsWRKY113 are up-regulated in BR IRGA 409, an iron-sensitive genotype, while in cultivars Nipponbare (moderately resistant) and EPAGRI 108 (resistant) the expression profiles of these transcription factors show similar behaviors. Here is also shown that some cis-regulatory elements known to be involved in other different stress responses can be linked to conditions of iron excess. Overall, here we support the role of WRKY transcription factors in iron stress tolerance with other important steps toward finding why some rice genotypes are more tolerant than others.

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Sediment-living organisms can be subjected to a multi-pollution condition due to an increase in the diversity of contaminants. Sediment mixtures of Mercury (Hg) and some polycyclic aromatics hydrocarbons like Pyrene (Pyr) are common in heavily industrialized coastal zones. In the present study, greater than (>) and less than (<) probable effect concentration levels (PELs) of Hg and Pyr were assessed using spiked sediments in order to determine combined (Hg + Pyr) effects in uptake, metabolization and oxidative balance in the polychaete Perinereis gualpensis at short and medium-term exposure. Hg + Pyr significantly influenced the uptake/kinetics of Hg and Pyr metabolite 1-OH-pyrene in polychaete tissues during the exposure time compared with separate treatments of each analyte (p < 0.05). Both the Hg-only and Pyr-only exposures significantly influenced both enzymatic and non-enzymatic responses respect to control groups (p < 0.05). The Hg-only treatment showed the worst scenario related to the activation and subsequent inhibition of glutathione S- transferase (GST) and peroxidase (GPx) activities, high levels of Thiol-groups (SH-groups), low antioxidant capacity (ACAP) and enhanced lipid peroxidation (TBARS) in the last days of exposure (p < 0.05). In contrast, ragworms exposed to Hg + Pyr showed a significant increase in both enzymatic and non-enzymatic activity during the first days of exposure and the absence of lipid peroxidation during the whole experiment. Our results suggest different oxidative stress scenarios in P. gualpensis when exposed to >PEL Hg concentration with

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Although flooding is one of the most important environmental stresses worldwide, not all plant species are intolerant to its effects. Species from semi-aquatic environments, such as rice, have the capacity to cope with flooding stress. Heat-shock proteins (Hsps) are thought to contribute to cellular homeostasis under both optimal and adverse growth conditions. Studies of gene expression in plants exposed to low levels of oxygen revealed the up-regulation of Hsp genes. However, it is not clear whether Hsp genes are transcribed as a function of tolerance or whether they represent a response to anoxic stress. Therefore, the accumulation of Hsp gene transcripts was investigated in two different cultivars, "Nipponbare" (flooding tolerant) and "IPSL 2070" (flooding sensitive), subjected to anoxic stress. Fifteen-day-old rice root seedlings from both cultivars were used. Four different treatments were performed: no anoxia (control); 24-h anoxia; 48-h anoxia; and 72-h anoxia. Anoxic stress was confirmed by the increased gene expression of alcohol dehydrogenase. The data obtained showed that both rice cultivars ("Nipponbare" and "IPSL 2070") accumulated Hsp gene transcripts under anoxic stress; however, the majority of the Hsp genes evaluated were responsive to anoxic stress in "IPSL 2070" (flooding sensitive), whereas in "Nipponbare" (flooding tolerant), only six genes were highly up-regulated. This suggests that although Hsps have an important role in the response to anoxia, they are not the major cause of tolerance.

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