BackgroundPlant disease resistance (R) genes with the nucleotide binding site (NBS) play an important role in offering resistance to pathogens. The availability of complete genome sequences of Brassica oleracea and Brassica rapa provides an important opportunity for researchers to identify and characterize NBS-encoding R genes in Brassica species and to compare with analogues in Arabidopsis thaliana based on a comparative genomics approach. However, little is known about the evolutionary fate of NBS-encoding genes in the Brassica lineage after split from A. thaliana.ResultsHere we present genome-wide analysis of NBS-encoding genes in B. oleracea, B. rapa and A. thaliana. Through the employment of HMM search and manual curation, we identified 157, 206 and 167 NBS-encoding genes in B. oleracea, B. rapa and A. thaliana genomes, respectively. Phylogenetic analysis among 3 species classified NBS-encoding genes into 6 subgroups. Tandem duplication and whole genome triplication (WGT) analyses revealed that after WGT of the Brassica ancestor, NBS-encoding homologous gene pairs on triplicated regions in Brassica ancestor were deleted or lost quickly, but NBS-encoding genes in Brassica species experienced species-specific gene amplification by tandem duplication after divergence of B. rapa and B. oleracea. Expression profiling of NBS-encoding orthologous gene pairs indicated the differential expression pattern of retained orthologous gene copies in B. oleracea and B. rapa. Furthermore, evolutionary analysis of CNL type NBS-encoding orthologous gene pairs among 3 species suggested that orthologous genes in B. rapa species have undergone stronger negative selection than those in B .oleracea species. But for TNL type, there are no significant differences in the orthologous gene pairs between the two species.ConclusionThis study is first identification and characterization of NBS-encoding genes in B. rapa and B. oleracea based on whole genome sequences. Through tandem duplication and whole genome triplication analysis in B. oleracea, B. rapa and A. thaliana genomes, our study provides insight into the evolutionary history of NBS-encoding genes after divergence of A. thaliana and the Brassica lineage. These results together with expression pattern analysis of NBS-encoding orthologous genes provide useful resource for functional characterization of these genes and genetic improvement of relevant crops.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-3) contains supplementary material, which is available to authorized users.

close-packed structures with lower surface energy and anisotropy, leading to great challenges in stabilizing and synthesizing 2D noble metal nanomaterials. To this end, a variety of synthetic strategies, such as hard-template-directed synthesis, capping-agent-assisted synthesis, and secondary assembly methods, have been developed for the synthesis of 2D noble metal-based nanostructures. [2] As one of the alternatives, self-assembly from 0D or 1D primary building blocks has been identified as a sophisticated and reliable approach for the generation of 2D noble metal nanostructures. [3] Ultrathin noble metal nanowires with high surface-tovolume ratios and atom utilization efficiency hold promising applications in widespread fields, including catalysis, optics devices, and biomedicine, etc. [4] Rational engineering of 1D nanowires into 2D nanosheets may bring about many novel structural characteristics, including high porosity, large area per unit volume, good flexibility, and an interconnected open pore structure. [5] Therefore, succinct-operated and controllable synthesis of ultrathin free-standing 2D nanosheets with 1D primary building blocks would be of great significance for fundamental scientific interest and technological applications, yet still remains greatly challenging.Herein, for the first time, we present a novel and facile one-pot, simultaneous stepwise self-assembly approach for the synthesis of freestanding porous Pd nanosheets (≈2.5 µm in lateral size and 10 nm in thickness) with the assistance of a functional polymer, poly(diallyldimethylammonium chloride) (PDDA; Figure S1, Supporting Information). Essentially, the obtained porous Pd nanosheets are flexibly knitted by numerous interweaved ultrathin nanowires. Different from the previously reported 2D noble metal nanosheets with smooth surface, [6,7] the obtained Pd nanosheets with large porosity and rough surface are achieved by particle spontaneous attachment and subsequent self-assembly in the one-pot synthesis process. To the best of our knowledge, this is the first report that the construction of 2D sheet-like Pd porous nanostructures through such a simple and efficient approach so far, and the elaborate adoption of eco-friendly PDDA as a structuredirecting agent also plays a crucial role in the formation of the Freestanding ultrathin 2D noble metal nanosheets have drawn enormous attention due to their potential applications in various fields. However, the synthesis of 2D noble metal nanosheets still remains a great challenge due to the lack of an intrinsic driving force for anisotropic growth of 2D structures. Here, a facile one-pot synthesis of ultrathin freestanding porous Pd nanosheets (≈2.5 µm in lateral size and 10 nm in thickness) flexibly knitted by interweaved ultrathin nanowires with the assistance of poly(diallyldimethylammonium chloride) is presented. Nanoparticles attachment and subsequent self-assembly in the synthetic process are responsible for the formation of such intriguing nanostructures. Moreover, finely controlling the p...

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Information on surgical site infection (SSI) after surgical treatment of ankle fracture is limited and remains controversial. The purpose of the present study was to determine the incidence and risk factors for SSI after open reduction and internal fixation (ORIF) of ankle fracture. Patients who underwent ORIF for ankle fracture at 3 centers between January 2015 and December 2016 were included. The potential risk factors for SSI included demographic variables, including age, sex, body mass index (BMI), hypertension, diabetes mellitus, heart disease, smoking, and excessive alcohol intake; blood test variables including preoperative white blood cell count, neutrophil count, red blood cell count, hemoglobin, total protein, albumin and globulin; injury- and surgery-related variables, including duration of operation (minutes), intraoperative blood loss, surgeon level, fracture site, accompanied dislocation, use of a drainage tube, and antibiotic use. Factors related with SSI occurrence were investigated by univariate analysis, and then by multivariate analysis. During hospitalization, 4.37% (66/1511) of patients developed SSI, which was deep in 1.32% (20/1510) and superficial in 3.05% (46/1510). The most common causative agent was polymicrobial (causing approximately half of all SSIs), followed by methicillin-resistant Staphylococcus aureus (MRSA). Multivariate analysis revealed that the significant risk factors for SSI occurrence were open injury, advanced age, incision cleanliness II – IV, high-energy injury, more experienced surgeon level, greater BMI, chronic heart disease, history of allergy, and preoperative neutrophil count > 75%. Preoperative preventative measures should be taken in patients with these conditions to lower the incidence of SSI after ORIF of ankle fracture.LEVEL OF EVIDENCE: Level III - Retrospective Comparative Study.