Brown planthopper (BPH), Nilaparvata lugens Stål, is one of the most devastating insect pests of rice (Oryza sativa L.). Currently, 30 BPHresistance genes have been genetically defined, most of which are clustered on specific chromosome regions. Here, we describe molecular cloning and characterization of a BPH-resistance gene, BPH9, mapped on the long arm of rice chromosome 12 (12L). BPH9 encodes a rare type of nucleotide-binding and leucine-rich repeat (NLR)-containing protein that localizes to the endomembrane system and causes a cell death phenotype. BPH9 activates salicylic acidand jasmonic acid-signaling pathways in rice plants and confers both antixenosis and antibiosis to BPH. We further demonstrated that the eight BPH-resistance genes that are clustered on chromosome 12L, including the widely used BPH1, are allelic with each other. To honor the priority in the literature, we thus designated this locus as BPH1/9. These eight genes can be classified into four allelotypes, BPH1/9-1, -2, -7, and -9. These allelotypes confer varying levels of resistance to different biotypes of BPH. The coding region of BPH1/9 shows a high level of diversity in rice germplasm. Homologous fragments of the nucleotide-binding (NB) and leucine-rich repeat (LRR) domains exist, which might have served as a repository for generating allele diversity. Our findings reveal a rice plant strategy for modifying the genetic information to gain the upper hand in the struggle against insect herbivores. Further exploration of natural allelic variation and artificial shuffling within this gene may allow breeding to be tailored to control emerging biotypes of BPH.brown planthopper | plant-insect interaction | CNL protein | allelotype | evolution

This study was designed to investigate the antioxidant activity, hepatoprotective effect, and phenolic composition of the ethyl acetate fraction (EAF) extracted from Houttuynia cordata tea. EAF was shown to exhibit strong ferric-reducing antioxidant power (FRAP) and scavenging activity against DPPH radical in vitro, and the antioxidant effects were further verified by suppressing CCl₄-induced oxidative stress in mouse liver at three tested doses of EAF (250, 500, and 1000 mg/kg bw). Pretreatment with EAF (1000 mg/kg bw) prior to CCl₄ administration significantly (p < 0.001) decreased the CCl₄-elevated levels of serum AST, ALT, alkaline phosphatase, total bilirubin, and hepatic MDA in mice and prevented the increases in GSH, SOD, and CAT caused by CCl₄. HPLC analysis revealed that three predominantly polyphenolic compounds present in EAF were quercitrin (111.7 μg/mg), quercetin (43.8 μg/mg), and hyperoside (29.1 μg/mg). These results combined with liver histopathology indicate that EAF possesses a significant protective effect against acute hepatotoxicity induced by CCl₄, which may be due to the strong antioxidant activity of phenolic components.

No abstract

No abstract

No abstract

Reversible addition-fragmentation chain transfer polymerization (RAFT) was developed for the controlled preparation of polystyrene (PS)/poly(4-vinylpyridine) (P4VP) triblock copolymers. First, PS and P4VP homopolymers were prepared using dibenzyl trithiocarbonate as the chain transfer agent (CTA). Then, PS-b-P4VP-b-PS and P4VP-b-PS-b-P4VP triblock copolymers were synthesized using as macro-CTA the obtained homopolymers PS and P4VP, respectively. The synthesized polymers had relatively narrower molecular weight distributions (M w /M n Ͻ 1.25), and the polymerization was controlled/living. Furthermore, the polymerization rate appeared to be lower when styrene was polymerized using P4VP as the macro-CTA, compared with polymerizing 4-vinylpyridine using PS as the macro-CTA. This was attributed to the different transfer constants of the P4VP and PS macro-CTAs to the styrene and the 4-vinylpyridine, respectively. The aggregates of the triblock copolymers with different compositions and chain architectures in water also were investigated, and the results are presented. Reducing the P4VP block length and keeping the PS block constant favored the formation of rod aggregates. Moreover, the chain architecture in which the P4VP block was in the middle of the copolymer chain was rather favorable to the rod assembly because of the entropic penalty associated with the looping of the middle-block P4VP to form the aggregate corona and tailing of the end-block PS into the core of the aggregates.

A monometallic (Ni 2+ , 1) and a bimetallic (Ni 2+ -Sm 3+ , 2) complexes based on the Salen-type Schiff-base ligand H 2 L (H 2 L ¼ N,N 0 -bis(3-methoxysalicylidene)ethylene-1,2-diamine) were synthesized and characterized by FT-IR, ESI-MS and X-ray crystallography. The catalysis results showed that the two complexes with different active species, could efficiently catalyze the bulk solvent-free melt ringopening polymerization (ROP) of L-lactide with moderate molecular weights and narrow molecular weight distributions. Especially, for the bimetallic complex 2, the involvement of rare ions effectively passivated the catalytic behavior on the ROP of L-lactide, while was in favor of the increase of polymeric molecular weights (M n ) and the polymerization controllability.

No abstract