Enhanced susceptibility to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine neurotoxicity in high-fat diet-induced obesity

Currently, obesity is considered a systemic inflammation; however, the effects of obesity on the vulnerability of dopaminergic neurons to oxidative stress are not fully defined. We evaluated the effects of high-fat diet-induced obesity (HF DIO) on neurotoxicity in mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Eight weeks after a HF or matched normal diet, a severe decrease in the levels of striatal dopamine and of nigral microtubule-associated protein 2, manganese superoxide dismutase, and tyrosine hydroxylase was observed in obese mice treated with subtoxic doses of MPTP (20 mg/kg) compared with the matched lean group. In addition, the levels of nitrate/nitrite and thiobarbituric acid-malondialdehyde adducts in the substantia nigra of obese mice were reciprocally elevated or suppressed by MPTP. Interestingly, striatal nNOS phosphorylation and dopamine turnover were elevated in obese mice after MPTP treatment, but were not observed in lean mice. The nitrotyrosine immunoreactivity for evaluation of nigral nitrogenous stress in obese mice with MPTP was higher than that in matched lean mice. At higher doses of MPTP (60 mg/kg), the mortality was higher in obese mice than in lean mice. These results suggest that DIO may increase the vulnerability of dopaminergic neurons to MPTP via increased levels of reactive oxygen and nitrogen species, and the role of nNOS phosphorylation in the MPTP toxicities and dopamine homeostasis should be further evaluated.     

The Arabidopsis RING E3 ubiquitin ligase AtAIRP2 plays combinatory roles with AtAIRP1 in abscisic acid-mediated drought stress responses

The ubiquitin (Ub)-26S proteasome pathway is implicated in various cellular processes in higher plants. AtAIRP1, a C3H2C3-type RING (for Really Interesting New Gene) E3 Ub ligase, is a positive regulator in the Arabidopsis (Arabidopsis thaliana) abscisic acid (ABA)-dependent drought response. Here, the AtAIRP2 (for Arabidopsis ABA-insensitive RING protein 2) gene was identified and characterized. AtAIRP2 encodes a cytosolic C3HC4-type RING E3 Ub ligase whose expression was markedly induced by ABA and dehydration stress. Thus, AtAIRP2 belongs to a different RING subclass than AtAIRP1 with a limited sequence identity. AtAIRP2-overexpressing transgenic (35S:AtAIRP2-sGFP) and atairp2 loss-of-function mutant plants exhibited hypersensitive and hyposensitive phenotypes, respectively, to ABA in terms of seed germination, root growth, and stomatal movement. 35S:AtAIRP2-sGFP plants were highly tolerant to severe drought stress, and atairp2 alleles were more susceptible to water stress than were wild-type plants. Higher levels of drought-induced hydrogen peroxide production were detected in 35S:AtAIRP2-sGFP as compared with atairp2 plants. ABA-inducible drought-related genes were up-regulated in 35S:AtAIRP2-sGFP and down-regulated in atairp2 progeny. The positive effects of AtAIRP2 on ABA-induced stress genes were dependent on SNF1-related protein kinases, key components of the ABA signaling pathway. Therefore, AtAIRP2 is involved in positive regulation of ABA-dependent drought stress responses. To address the functional relationship between AtAIRP1 and AtAIRP2, FLAG-AtAIRP1 and AtAIRP2-sGFP genes were ectopically expressed in atairp2-2 and atairp1 plants, respectively. Constitutive expression of FLAG-AtAIRP1 and AtAIRP2-sGFP in atairp2-2 and atairp1 plants, respectively, reciprocally rescued the loss-of-function ABA-insensitive phenotypes during germination. Additionally, atairp1/35S:AtAIRP2-sGFP and atairp2-2/35S:FLAG-AtAIRP1 complementation lines were more tolerant to dehydration stress relative to atairp1 and atairp2-2 single knockout plants. Overall, these results suggest that AtAIRP2 plays combinatory roles with AtAIRP1 in Arabidopsis ABA-mediated drought stress responses.     

The suppression of the glutelin storage protein gene in transgenic rice seeds results in a higher yield of recombinant protein

Glutelin is a major seed storage protein, accounting for 60?C80?% of the total endosperm protein content in rice. To test whether we could augment the expression of an introduced recombinant protein in rice by suppressing the glutelin gene, we generated transgenic glutelin RNAi (glu RNAi) rice seeds. RNA gel blot analyses confirmed that the endogenous glutelin gene was severely suppressed in these transgenic rice lines. RT-PCR analysis further revealed that all the members of glutelin multigene family were downregulated. Transgenic glu RNAi rice seeds expressing a recombinant red fluorescent protein (RFP) showed stronger fluorescence than seeds transformed with the RFP gene only. Western blot analysis further revealed that the relative accumulation of RFP in glu RNAi seeds was twofold higher than that in the RFP-only transgenic seeds. These results suggest that RNAi targeting of an endogenous storage protein could be of great utility in obtaining higher transgene expression in genetically engineered rice and other plant lines.     

The role of the ubiquitin proteasome system in synapse remodeling and neurodegenerative diseases

The ubiquitin proteasome system is a potent regulatory mechanism used to control protein stability in numerous cellular processes, including neural development. Many neurodegenerative diseases are featured by the accumulation of UPS-associated proteins, suggesting the UPS dysfunction may be crucial for pathogenesis. Recent experiments have highlighted the UPS as a key player during synaptic development. Here we summarize recent discoveries centered on the role of the UPS in synapse remodeling and draw attention to the potential link between the synaptic UPS dysfunction and the pathology of neurodegenerative diseases.     

Inhibitory effect of naringenin chalcone on inflammatory changes in the interaction between adipocytes and macrophages

Obese adipose tissue is characterized by an enhanced infiltration of macrophages. It is considered that the paracrine loop involving monocyte chemoattractant protein (MCP)-1 and tumor necrosis factor (TNF)-alpha between adipocytes and macrophages establishes a vicious cycle that augments the inflammatory changes and insulin resistance in obese adipose tissue. Polyphenols, which are widely distributed in fruit and vegetables, can act as antioxidants and some of them are also reported to have anti-inflammatory properties. Tomato is one of the most popular and extensively consumed vegetable crops worldwide, which also contains many flavonoids, mainly naringenin chalcone. We investigated the effect of flavonoids, including naringenin chalcone, on the production of proinflammatory mediators in lipopolysaccharide (LPS)-stimulated macrophages and in the interaction between adipocytes and macrophages. Naringenin chalcone inhibited the production of TNF-alpha, MCP-1, and nitric oxide (NO) by LPS-stimulated RAW 264 macrophages in a dose-dependent manner. Coculture of 3T3-L1 adipocytes and RAW 264 macrophages markedly enhanced the production of TNF-alpha, MCP-1, and NO compared with the control cultures; however, treatment with naringenin chalcone dose-dependently inhibited the production of these proinflammatory mediators. These results indicate that naringenin chalcone exhibits anti-inflammatory properties by inhibiting the production of proinflammatory cytokines in the interaction between adipocytes and macrophages. Naringenin chalcone may be useful for ameliorating the inflammatory changes in obese adipose tissue.     

Biological control of oilseed rape Sclerotinia stem rot by Bacillus subtilis strain Em7

In the present study, the endophytic bacterium Bacillus subtilis strain Em7 (GU258545.1) was evaluated as a biological control agent for Sclerotinia sclerotiorum on oilseed rape. In petri dish, strain Em7 not only strongly inhibited pathogen mycelium growth but also germination of sclerotia at concentrations between 10⁹ and 10¹¹ colony forming unit (CFU)·ml^?1. Scanning electron microscopy and transmission electron microscopy studies revealed that in the presence of strain Em7, hyphae of S. sclerotiorum showed leakage and disintegration of hyphal cytoplasm. Furthermore, the strain Em7 showed a broad antifungal spectrum on mycelium growth of numerous important plant pathogenic fungi. Light microscopic observations revealed that strain Em7 caused morphological alterations including increased branching, swelling and collapse of cytoplasm. In the greenhouse, spray treatments of cell suspensions of strain Em7 (1×10⁹ CFU·ml^?1) reduced leaf and stem rot incidence and severity in the seedling and blossom stage. The control efficacy was higher when strain Em7 cell suspension was applied one day prior to inoculation of the pathogen than after inoculation. Three-year field trials showed that two applications of strain Em7 cell suspension at blossom stage significantly reduced disease incidence and severity by 50–70%. There was no significant difference in control efficacy among treatments with strain Em7 cell suspension and the fungicides containing carbendazim or tebuconazole (P = 0.05). Thus, our results strongly suggest that B. subtilis strain Em7 is a promising biological control agent for control of oilseed rape Sclerotinia stem rot.     

Molecular Dissection of Bombyx mori Nucleopolyhedrovirus orf8 Gene

Viruses including baculoviruses are obligatory parasites, as their genomes do not encode all the proteins required for replication. Therefore, viruses have evolved to exploit the behavior and the physiology of their hosts and often eoevolved with their hosts over millions of years. Recent comparative analyses of complete genome sequences of baculoviruses revealed the patterns of gene acquisitions and losses that have occurred during baculovirus evolution. In addition, knowledge of virus genes has also provided understanding of the mechanism of baculovirus infection including replication, species-specific virulence and host range. The Bm8 gene of Bombyx mori nucleopolyhedrovirus (NPV) and its homologues are found only in group I NPV genomes. The Autographa californica NPV Acl6 gene is a homologue of Bm8 and, encodes a viral structural protein. It has been shown that Bm8/Ac 16 interacts with baculoviral and cellular proteins. Bm8/Ac 16 interacts with baculoviral IE1 that is facilitated by coiled coil domains, and the interaction with IE1 is important for Bin8 function. Ac16 also forms a complex with viral FP25 and cellular actin and associates with membranes via palmitoylation. These data suggested that this gene family encodes a multifunctional protein that accomplishes specific needs of group INPVs.