Evaluation of genetic diversity and linkage disequilibrium in Korean-bred rice varieties using SSR markers

Background: In order to evaluate the variation among different rice types, the genetic diversity in a rice collection composed by 59 breeding lines, 23 landraces, 18 weedy rice lines, and 35 introduced lines that collected from countries worldwide was analyzed using 134 simple sequence repeat markers. Results: In total, 1264 alleles were identified (average, 9.43 per locus). Rare alleles made up a large portion (58.4%) of the detected alleles, and 29 unique alleles associated with rice accessions were also discovered. A model-based structural analysis revealed the presence of three subpopulations. The genetic relationships revealed by the neighbour-joining tree method were fairly consistent with the structure-based membership assignments for most of the accessions. A total of 105 accessions (79.5%) showed a clear relationship to each cluster, while the remaining 27 accessions (20.5%) were categorized as admixtures. Linkage disequilibrium (LD) patterns and distributions are of fundamental importance for genome-wide association mapping. The mean r² value for all intrachromosomal loci pairs was 0.1286. The LD between linked markers decreased with the genetic distance between pairs of linked loci. Conclusions: These results will provide an effective aid for future allele mining, association genetics, mapping and cloning gene(s), germplasm conservation, and improvement programs.

Significance of Interleukin-17A in patients with nasal polyposis.

Background：Interleukin-17A (IL-17A) is a key inflammatory cytokine in many disorders, while the significance of IL-17A in nasal polyposis (NP) is still obscure. This study aimed to investigate the expression of IL-17A in nasal polyps from both atopic and nonatopic patients and its associations with clinical and histological features. Methods: In all, 30 patients with NP were included, and were grouped into atopic and nonatopic patients according to skin prick test (SPT). Disease severity was evaluated by symptom score, endoscopy score and CT score. Histological characteristics were assessed by eosinophilic infiltration, basement membrane (BM) thickness, epithelial damage, squamous metaplasia, and goblet cell hyperplasia. IL-17A expression in polyps was detected by ELISA and immunohistochemistry. Results: Endoscopy score and CT score were significantly higher in atopic NP patients than in nonatopic NP patients (P<0.05). IL-17A levels were significantly upregulated in both atopic (P<0.01) and nonatopic (P<0.05) patients versus controls. Furthermore, IL-17A levels were significantly higher in the atopic group versus nonatopic group. Significantly positive correlations were found between IL-17A levels and CT scores, eosinophilic infiltration and BM thicknesses. Conclusions: These results indicated that expression of IL-17A was significantly upregulated in NP patients and was more severe in atopic NP patients, suggesting that IL-17A may play an important role in the pathology of NP and atopy may contribute to NP by stimulating the production of IL-17A.