REV7-p53 interaction inhibits ATM-mediated DNA damage signaling.

REV7 is an abundant, multifunctional protein that is a known factor in cell cycle regulation and in several key DNA repair pathways including Trans-Lesion Synthesis (TLS), the Fanconi Anemia (FA) pathway, and DNA Double-Strand Break (DSB) repair pathway choice. Thus far, no direct role has been studied for REV7 in the DNA damage response (DDR) signaling pathway. Here we describe a novel function for REV7 in DSB-induced p53 signaling. We show that REV7 binds directly to p53 to block ATM-dependent p53 Ser15 phosphorylation. We also report that REV7 is involved in the destabilization of p53. These findings affirm REV7's participation in fundamental cell cycle and DNA repair pathways. Furthermore, they highlight REV7 as a critical factor for the integration of multiple processes that determine viability and genome stability.

Toxicity effects of multi-walled carbon nanotubes (MWCNTs) nanomaterial on the common carp (Cyprinus carpio L. 1758) in laboratory conditions.

Over the past decade, the usages of carbon nanotubes in various industries have been increased. Multi-walled carbon nanotubes (MWCNTs) are special form of carbon nanotubes which are used as nano-absorbents for various purposes of different industries due to their high surface to volume ratio. In aquatic environments these active nano-agents can easily absorb and accumulate in animal cells and tissues due to their tiny sizes and induce toxicity effects on bio-organisms mainly via pro-oxidants production. The present study assayed MWCNTs toxicity effects on anti-oxidative enzymes activities, serum hormonal and biochemical stress biomarkers, hematology parameters, histopathology and growth performance of the common carp Cyprinus carpio. Experiment was conducted in five treatments including 0 (control), 5, 10, 15, 20 mg/l MWCNTs in triplicate and each of the experimental tanks consisted of a 400-l recirculating system, stocked with, 20 fish (12 ± 2 g) for 28 days. The results indicated that by increasing the concentrations of the MWCNTs weight gain, specific growth rate and survival rate parameters were decreased. The findings showed that cortisol secretion, blood glucose level and anti-oxidative enzymes activities were increased with the increase of MWCNTs concentrations in the treatments. Histopathology results depicted that 15 and 20 mg/l MWCNTs caused hyperplasia, telangiectasia, apoptosis, and necrosis damages in gills and also, apoptosis, sinusoidal spaces, fibrosis, hepatocyte degeneration and necrosis in the liver of C. carpio. Despite these findings, further researches on effects of nanomaterials on aquatic organisms and ecosystems are essential to protect these environments against the newly found nanomaterials hazards.

Arabidopsis genes, AtNPR1, AtTGA2 and AtPR-5, confer partial resistance to soybean cyst nematode (Heterodera glycines) when overexpressed in transgenic soybean roots.

BACKGROUND: Extensive studies using the model system Arabidopsis thaliana to elucidate plant defense signaling and pathway networks indicate that salicylic acid (SA) is the key hormone triggering the plant defense response against biotrophic and hemi-biotrophic pathogens, while jasmonic acid (JA) and derivatives are critical to the defense response against necrotrophic pathogens. Several reports demonstrate that SA limits nematode reproduction. RESULTS: Here we translate knowledge gained from studies using Arabidopsis to soybean. The ability of thirty-one Arabidopsis genes encoding important components of SA and JA synthesis and signaling in conferring resistance to soybean cyst nematode (SCN: Heterodera glycines) are investigated. We demonstrate that overexpression of three of thirty-one Arabidoposis genes in transgenic soybean roots of composite plants decreased the number of cysts formed by SCN to less than 50% of those found on control roots, namely AtNPR1(33%), AtTGA2 (38%), and AtPR-5 (38%). Three additional Arabidopsis genes decreased the number of SCN cysts by 40% or more: AtACBP3 (53% of the control value), AtACD2 (55%), and AtCM-3 (57%). Other genes having less or no effect included AtEDS5 (77%), AtNDR1 (82%), AtEDS1 (107%), and AtPR-1 (80%), as compared to control. Overexpression of AtDND1 greatly increased susceptibility as indicated by a large increase in the number of SCN cysts (175% of control). CONCLUSIONS: Knowledge of the pathogen defense system gained from studies of the model system, Arabidopsis, can be directly translated to soybean through direct overexpression of Arabidopsis genes. When the genes, AtNPR1, AtGA2, and AtPR-5, encoding specific components involved in SA regulation, synthesis, and signaling, are overexpressed in soybean roots, resistance to SCN is enhanced. This demonstrates functional compatibility of some Arabidopsis genes with soybean and identifies genes that may be used to engineer resistance to nematodes.

Engineered resistance and hypersusceptibility through functional metabolic studies of 100 genes in soybean to its major pathogen, the soybean cyst nematode.

During pathogen attack, the host plant induces genes to ward off the pathogen while the pathogen often produces effector proteins to increase susceptibility of the host. Gene expression studies of syncytia formed in soybean root by soybean cyst nematode (Heterodera glycines) identified many genes altered in expression in resistant and susceptible roots. However, it is difficult to assess the role and impact of these genes on resistance using gene expression patterns alone. We selected 100 soybean genes from published microarray studies and individually overexpressed them in soybean roots to determine their impact on cyst nematode development. Nine genes reduced the number of mature females by more than 50 % when overexpressed, including genes encoding ascorbate peroxidase, ß-1,4-endoglucanase, short chain dehydrogenase, lipase, DREPP membrane protein, calmodulin, and three proteins of unknown function. One gene encoding a serine hydroxymethyltransferase decreased the number of mature cyst nematode females by 45 % and is located at the Rhg4 locus. Four genes increased the number of mature cyst nematode females by more than 200 %, while thirteen others increased the number of mature cyst nematode females by more than 150 %. Our data support a role for auxin and ethylene in susceptibility of soybean to cyst nematodes. These studies highlight the contrasting gene sets induced by host and nematode during infection and provide new insights into the interactions between host and pathogen at the molecular level. Overexpression of some of these genes result in a greater decrease in the number of cysts formed than recognized soybean cyst nematode resistance loci.