Plants initiate immunity by cell-surface pattern-recognition receptors (PRRs), which perceive non-self molecules. PRRs are predominantly receptor serine/threonine (Ser/Thr) kinases that are evolutionarily related to animal interleukin-1 receptor-associated kinase (IRAK)/Pelle-soluble kinases. However, how the activity of these receptor kinases is modulated remains poorly understood. We report that the Arabidopsis PRR chitin elicitor receptor kinase 1 (CERK1) is autophosphorylated in unstimulated cells at tyrosine (Tyr), a modification that is required for CERK1 activation upon binding to the fungal cell wall component chitin. Upon chitin activation, CERK1 recruits the CERK1-interacting protein phosphatase 1 (CIPP1), a predicted Ser/Thr phosphatase, to dephosphorylate Tyr and dampen CERK1 signaling. CIPP1 subsequently dissociates from Tyr-dephosphorylated CERK1, allowing CERK1 to regain Tyr autophosphorylation and return to a standby state. This work sheds light onto plant chitin signaling and shows that a receptor kinase and phosphatase can coordinately regulate signal transduction of a receptor kinase through a phosphorylation cycle.

A stereoselective synthesis of (+)-herboxidiene is described. The convergent synthesis utilized a Suzuki cross-coupling reaction to assemble the key segments. The synthesis of the functionalized tetrahydropyran ring utilized an Achmatowicz reaction as the key step. The synthesis of the C10-C19 segment was accomplished using Brown's crotylboration, asymmetric alkylation, and a stereoselective allylic chlorination reaction.Researchers at Monsanto (USA) isolated herboxidiene (1, Figure 1) from Streptomyces chromofuscus in 1992. 1 It displayed highly potent and selective phytotoxicity against a myriad of broad leaf weeds over co-planted wheat. 1 Subsequently, in 2002, Yoshida and coworkers isolated six structurally related compounds, including GEX1 from a culture broth of Streptomyces sp. 2 One of the compounds, GEX1A was identified as herboxidiene (1) and it was shown to reduce plasma cholesterol by up-regulating gene expression of low-density lipoprotein receptors. 3 Furthermore, it induced both G1 and G2/M cell cycle arrest in a human normal fibroblast cell line, WI-38. 4 The initial structural assignment of herboxidiene was carried out by chemical degradation and spectroscopic studies. 5 Ultimately, the first total synthesis by Kocienski and co-workers 6 confirmed the relative and absolute configuration of herboxidiene/GEX1A (1). Important biological properties, low abundance, and the interesting structural features of 1 led to considerable interest in its synthesis and biological studies. Subsequently, three other total syntheses were accomplished by Banwell, Panek, and Forsyth. 7 Edmonds and co-workers reported simplified aromatic hybrids of 1 with interesting herbicidal activity. 8 Herein we report an asymmetric synthesis of (+)-herboxidiene that can be amenable to analog preparation.Our retrosynthesis of (+)-herboxidiene (1) is shown in Figure 1. We planned to utilize a Suzuki cross coupling reaction similar to Murray and Forsyth 7c to attach the vinyl iodide 2 and boronate 3 at a late-stage in the synthesis. The functionalized tetrahydropyran ring 2 could be constructed from furfural derivative 4 via oxidative Achmatowicz rearrangement followed by reduction of the resulting hemiketal. The boronate segment 3 could be derived from cross-metathesis of olefin 5 and vinyl pinacol boronate. Olefin 5 would be obtained by asymmetric alkylation with allylic iodide 6, which can be obtained from an asymmetric crotylboration with an appropriate aldehyde.The synthesis of vinyl iodide 2 (Scheme 1) commenced by treatment of aldehyde 4 9 with allylmagnesium bromide followed by lipase resolution of the resulting homoallylic alcohol akghosh@purdue.edu . Supporting Information Available: Experimental procedures and 1 H-and 13 C-NMR spectra for all new compounds. This material is available free of charge via the Internet at http://pubs.acs.org. NIH Public Access Author ManuscriptOrg Lett. Author manuscript; available in PMC 2012 January 7. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript to ...

LIHR is a safe and feasible procedure. It has significantly better effects on postoperative pains and hernia relapse than Lichtenstein tension-free hernia repair.

Research in plant molecular biology involves DNA purification on a daily basis. Although different commercial kits enable convenient extraction of high-quality DNA from E. coli cells, PCR and agarose gel samples as well as plant tissues, each kit is designed for a particular type of DNA extraction work, and the cost of purchasing these kits over a long run can be considerable. Furthermore, a simple method for the isolation of binary plasmid from Agrobacterium tumefaciens cells with satisfactory yield is lacking. Here we describe an easy protocol using homemade silicon dioxide matrix and seven simple solutions for DNA extraction from E. coli and A. tumefaciens cells, PCR and restriction digests, agarose gel slices, and plant tissues. Compared with the commercial kits, this protocol allows rapid DNA purification from diverse sources with comparable yield and purity at negligible cost. Following this protocol, we have demonstrated: (1) DNA fragments as small as a MYC-epitope tag coding sequence can be successfully recovered from an agarose gel slice; (2) Miniprep DNA from E. coli can be eluted with as little as 5 μl water, leading to high DNA concentrations (>1 μg/μl) for efficient biolistic bombardment of Arabidopsis seedlings, polyethylene glycol (PEG)-mediated Arabidopsis protoplast transfection and maize protoplast electroporation; (3) Binary plasmid DNA prepared from A. tumefaciens is suitable for verification by restriction analysis without the need for large scale propagation; (4) High-quality genomic DNA is readily isolated from several plant species including Arabidopsis, tobacco and maize. Thus, the silicon dioxide matrix-based DNA purification protocol offers an easy, efficient and economical way to extract DNA for various purposes in plant research.