Effects of S-Abscisic Acid (S-ABA) on Seed Germination,Seedling Growth,and Asr1 Gene Expression Under Drought Stress in Maize

The objective of this study was to evaluate the ability of the phytohormone S-abscisic acid (S-ABA) to protect maize seedlings grown under drought stress and to measure their increased drought tolerance. The maize hybrids ‘Zhengdan 958’ (ZD958; drought tolerant) and ‘Xundan 20’ (XD20; drought sensitive) were treated with nutrient solutions of different concentrations (1, 2, 4, 8, and 10 mg/kg) of S-ABA under polyethylene glycol (PEG, 15% w/v, MW 6000) simulated drought stress. Optimal concentrations of S-ABA were designed to be sprayed onto the leaves of seedlings, and their effect on endogenous ABA, malondialdehyde (MDA), osmotic substances, antioxidant enzyme activities, and Asr1 gene expression in seedlings were studied. Results indicated that, under drought stress, S-ABA treatment significantly improved maize seed germination rate (GR), germination energy (GE), and seedling biomass (p < 0.05). After spraying 4 mg/kg S-ABA onto leaves, the endogenous hormone ABA, osmotic substances, antioxidant enzyme activities, and expressive quantity of the Asr1 gene were extended and MDA content dropped significantly (p < 0.05). Moreover, ZD 958 endogenous ABA content, osmotic substances content, antioxidant enzyme activity and Asr1 gene expressive quantity were higher than that of XD 20 (p < 0.05). In conclusion, S-ABA treatment increased the content of endogenous ABA, induced an increase in antioxidant enzyme activity and Asr1 gene expression level, reduced the oxidative damage caused by drought to maize leaves, and improved the adaptability of maize seedlings to withstand drought stress. The promoting effect of S-ABA on the drought-tolerant variety ZD 958 was more obvious (p < 0.05). These results serve as a reference for the use of S-ABA in mitigating drought stress in maize.

     

Astragaloside suppresses tumor necrosis factor receptor-associated factor 5 signaling pathway and alleviates neurodegenerative changes in retinal pigment epithelial cells induced by isoflurane

Epidemiological studies showed that isoflurane, a general anesthetic widely used in surgery including those for the children, is associated with impairment of neurodevelopment and neurodegenerative diseases, such as Alzheimer’s disease (AD) and age-related macular degeneration (AMD), which are related to the accumulation of reactive oxygen species (ROS). Astragaloside (AS) is an antioxidant derivative from a traditional Chinese herbal medicine Astragalus membraneaceus Bunge. In this study, we used retinal pigment epithelial cells, which share plenty of features with neurodegenerative diseases such as AD and AMD to investigate the effect of AS. Cell cycle re-entry and proapoptosis were seen in retinal pigment epithelium (RPE) cells treated with isoflurane, which was alleviated by pretreatment of AS. Further, tumor necrosis factor receptor-associated factor 5 (TRAF5) and downstream nuclear factor-κB (NF-κB) were investigated to elucidate the molecular mechanism underlying protective effect of AS. RPE cells exposed to isoflurane expressed higher TRAF5 and NF-κB than those pretreated with AS, suggesting a critical role of TRAF5 therein. In Morris water maze (MWM) assay, Sprague-Dawley rats pretreated with AS and then exposed to isoflurane spent less time in swimming to the platform, and their TRAF5 expression was significantly lower than those received anesthesia alone. Further studies on the consequence of forced downregulation or upregulation are warranted that may employ cutting-edge technologies such as optogenetics to overcome the difficulties in manipulating expression of TRAF5. Although the link between TRAF5 and neurodegeneration requires more in-depth investigations, our study provide a novel hint on the pathological mechanism of isoflurane and suggest a potential target for eliminating persistent side effect of anesthesia.     

Apoptin induces pyroptosis of colorectal cancer cells via the GSDME-dependent pathway

Apoptin is a small molecular weight protein encoded by the VP3 gene of chicken anemia virus (CAV). It can induce apoptosis of tumor cells and play anti-tumorigenic functions. In this study, we identified a time-dependent inhibitory role of apoptin on the viability of HCT116 cells. We also demonstrated that apoptin induces pyroptosis through cleaved caspase 3, and with a concomitant cleavage of gasdermin E (GSDME) rather than GSDMD. GSDME knockdown switched the apoptin-induced cell death from pyroptosis to apoptosis in vitro. Furthermore, we demonstrated that the effect of apoptin on GSDME-dependent pyroptosis could be mitigated by caspase-3 and caspase-9 siRNA knockdown. Additionally, apoptin enhanced the intracellular reactive oxygen species (ROS), causing aggregation of the mitochondrial membrane protein Tom20. Moreover, bax and cytochrome c were released to the activating caspase-9, eventually triggering pyroptosis. Therefore, GSDME mediates the apoptin-induced pyroptosis through the mitochondrial apoptotic pathway. Finally, using nude mice xenografted with HCT116 cells, we found that apoptin induces pyroptosis and significantly inhibits tumor growth. Based on this mechanism, apoptin may provide a new strategy for colorectal cancer therapy.     

Peroxisome-generated succinate induces lipid accumulation and oxidative stress in the kidneys of diabetic mice

Diabetes normally causes lipid accumulation and oxidative stress in the kidneys, which plays a critical role in the onset of diabetic nephropathy; however, the mechanism by which dysregulated fatty acid metabolism increases lipid and reactive oxygen species (ROS) formation in the diabetic kidney is not clear. As succinate is remarkably increased in the diabetic kidney, and accumulation of succinate suppresses mitochondrial fatty acid oxidation and increases ROS formation, we hypothesized that succinate might play a role in inducing lipid and ROS accumulation in the diabetic kidney. Here we demonstrate a novel mechanism by which diabetes induces lipid and ROS accumulation in the kidney of diabetic animals. We show that enhanced oxidation of dicarboxylic acids by peroxisomes leads to lipid and ROS accumulation in the kidney of diabetic mice via the metabolite succinate. Furthermore, specific suppression of peroxisomal β-oxidation improved diabetes-induced nephropathy by reducing succinate generation and attenuating lipid and ROS accumulation in the kidneys of the diabetic mice. We suggest that peroxisome-generated succinate acts as a pathological molecule inducing lipid and ROS accumulation in kidney, and that specifically targeting peroxisomal β-oxidation might be an effective strategy in treating diabetic nephropathy and related metabolic disorders.     

Focus: The Science of Stress: PTSD Among Shidu Parents in China: The Roles of Personality Types and Social Support

Background: The psychological problems of Shidu Parents (SDP) under the China’s One-Child Policy have been documented. The purpose of this study was to investigate the relationships among personality types, social support, and post-traumatic stress disorder (PTSD) in SDP. Methods: The PTSD Checklist-Civilian Version (PCL-C), The Big Five Personality Traits (NEO), and Social Support Revalued Scale (SSRS) were administered to the sample of 149 SDP who were over 50 years old and had lost their only child more than one year ago. Results: Among SDP, mothers were more likely to develop PTSD than fathers (χ² = 11.16, p < 0.01). Parents who were extraverted had a lower risk of developing PTSD-related symptoms (χ² = 8.58, p < 0.01), and the effect of neuroticism was significant (χ² = 23.73, p < 0.01). The more social support parents utilized, the lower the incidence of PTSD (t = 4.56, p < 0.01). The result of multilevel linear regression showed that sex, neuroticism, and objective social support remained significantly different after combining all personality types and social support systems in the same model. Social support partially mediated the relationship between neuroticism and PTSD. Meanwhile, it was a complete mediator between extraversion and PTSD. Conclusions: Female sex/gender, neuroticism, and introversion were risk factors of developing PTSD, while receiving social support protected SDP from developing PTSD symptoms. Losing an only child is undoubtedly an enormous disaster for the family, which has become a huge, unavoidable social problem that must be addressed in China.     

The LG3 module of laminin-5 harbors a binding site for integrin alpha3beta1 that promotes cell adhesion, spreading, and migration

Laminins are a family of extracellular matrix glycoproteins involved in cell adhesion and migration. A major obstacle to understanding their structure-function relationships is the lack of small laminin domains capable of replicating integrin-binding, cell-adhesive, and migratory functions of the intact molecule. Here, we show that the recombinant LG3 (rLG3) module (26 kDa) of laminin-5 (Ln-5) alpha(3) chain replicated key Ln-5 activities. rLG3 but not rLG1 or rLG2 supported cell adhesion and migration of at least two distinct cell lines, in an integrin alpha(3)beta(1)-dependent manner. Cell adhesion to rLG3 was regulated by divalent cations and accompanied by cell spreading and tyrosine phosphorylation of FAK focal adhesion kinase. The integrin binding activity of rLG3 was confirmed by rLG3 affinity chromatography of detergent cell lysates, which resulted in specific purification of integrin alpha(3)beta(1). To our knowledge, this is the first report directly demonstrating that a recombinant laminin LG module is an active domain capable of supporting integrin-dependent cell adhesion and migration.     

Recombinant protein composed of Pseudomonas exotoxin A, outer membrane proteins I and F as vaccine against P. aeruginosa infection

We have constructed a chimeric protein composed of the receptor binding and membrane translocation domains of Pseudomonas exotoxin A (PE) with the outer membrane proteins I and F, together designated as PEIF. The potential of PEIF as a vaccine against Pseudomonas infection was evaluated in BALB/c mice and New Zealand white rabbits. We examined titers of anti-PE and anti-OprF antibodies, and the ability both to neutralize PE cytotoxicity and to increase opsonophagocytic uptake of Pseudomonas aeruginosa strain PAO1, serogroups 2 and 6. The results showed that PEIF can induce antibodies not only to neutralize the PE cytotoxicity but also to promote the uptake of various strains of P. aeruginosa by murine peritoneal macrophages. In a burned mouse model, PEIF afforded significant protection against infection by the homologous P. aeruginosa strain PAO1, heterologous serogroup 2, and the PE hyperproducing strain PA103. These observations thus indicate that PEIF may be used as a novel vaccine against P. aeruginosa infection. Received: 10 March 1999 / Received revision: 21 April 1999 / Accepted: 16 May 1999     

Behavior of Pythium torulosum Zoospores During Their Interaction with Tobacco Roots and Bacillus cereus

Bacillus cereus UW85 suppresses seedling damping-off diseases caused by Oomycetes and produces antibiotics that inhibit development of Oomycetes in culture. The goal of this study was to determine how UW85 and its antibiotics affected the behavior of an Oomycete, Pythium torulosum, in its interaction with plant roots. We studied tobacco seedlings inoculated with zoospores of P. torulosum and UW85 culture, culture filtrate, washed cells, antibiotics (zwittermicin A or kanosamine), purified from cultures of UW85, and UW030, a mutant of UW85 that does not suppress disease and does not produce the antibiotics. Microscopic observation revealed that all of the treatments inhibited zoospore activity around roots and encystment on roots. Treatment with UW85 culture, culture filtrate, zwittermicin A, or kanosamine delayed cyst germination and the elongation rate of germ tubes, whereas treatment with UW030 or washed UW85 cells did not. In an in vitro seedling bioassay of disease suppression, the antibiotics, zwittermicin A and kanosamine, suppressed disease singly or together, although UW85 culture suppressed disease more effectively than did the antibiotics. The results show that B. cereus cultures affect zoospore behavior in the presence of roots, and B. cereus-produced antibiotics, zwittermicin A and kanosamine, contribute to disease suppression and inhibition of germ tube elongation in the presence of the plant root. Received: 9 September 1998 / Accepted: 13 October 1998