An EST-SSR Linkage Map of Raphanus sativus and Comparative Genomics of the Brassicaceae†

Raphanus sativus (2n = 2x = 18) is a widely cultivated member of the family Brassicaceae, for which genomic resources are available only to a limited extent in comparison to many other members of the family. To promote more genetic and genomic studies and to enhance breeding programmes of R. sativus, we have prepared genetic resources such as complementary DNA libraries, expressed sequences tags (ESTs), simple sequence repeat (SSR) markers and a genetic linkage map. A total of 26 606 ESTs have been collected from seedlings, roots, leaves, and flowers, and clustered into 10 381 unigenes. Similarities were observed between the expression patterns of transcripts from R. sativus and those from representative members of the genera Arabidopsis and Brassica, indicating their functional relatedness. The EST sequence data were used to design 3800 SSR markers and consequently 630 polymorphic SSR loci and 213 reported marker loci have been mapped onto nine linkage groups, covering 1129.2 cM with an average distance of 1.3 cM between loci. Comparison of the mapped EST-SSR marker positions in R. sativus with the genome sequence of A. thaliana indicated that the Brassicaceae members have evolved from a common ancestor. It appears that genomic fragments corresponding to those of A. thaliana have been doubled and tripled in R. sativus. The genetic map developed here is expected to provide a standard map for the genetics, genomics, and molecular breeding of R. sativus as well as of related species. The resources are available at http://marker.kazusa.or.jp/Daikon

SNP Discovery and Linkage Map Construction in Cultivated Tomato

Few intraspecific genetic linkage maps have been reported for cultivated tomato, mainly because genetic diversity within Solanum lycopersicum is much less than that between tomato species. Single nucleotide polymorphisms (SNPs), the most abundant source of genomic variation, are the most promising source of polymorphisms for the construction of linkage maps for closely related intraspecific lines. In this study, we developed SNP markers based on expressed sequence tags for the construction of intraspecific linkage maps in tomato. Out of the 5607 SNP positions detected through in silico analysis, 1536 were selected for high-throughput genotyping of two mapping populations derived from crosses between ‘Micro-Tom’ and either ‘Ailsa Craig’ or ‘M82’. A total of 1137 markers, including 793 out of the 1338 successfully genotyped SNPs, along with 344 simple sequence repeat and intronic polymorphism markers, were mapped onto two linkage maps, which covered 1467.8 and 1422.7 cM, respectively. The SNP markers developed were then screened against cultivated tomato lines in order to estimate the transferability of these SNPs to other breeding materials. The molecular markers and linkage maps represent a milestone in the genomics and genetics, and are the first step toward molecular breeding of cultivated tomato. Information on the DNA markers, linkage maps, and SNP genotypes for these tomato lines is available at http://www.kazusa.or.jp/tomato/

Development of high-density genetic linkage maps and identification of loci for chestnut gall wasp resistance in Castanea spp

Castanea sativais an important multipurpose species in Europe for nut and timber production as well as for its role in the landscape and in the forest ecosystem. This species has low tolerance to chestnut gall wasp (Dryocosmus kuriphilusYasumatsu), which is a pest that was accidentally introduced into Europe in early 2000 and devastated forest and orchard trees. Resistance to the gall wasp was found in the hybrid cultivar 'Bouche de Betizac' (C. sativaxC. crenata) and studied by developing genetic linkage maps using a population derived from a cross between 'Bouche de Betizac' and the susceptible cultivar 'Madonna' (C. sativa). The high-density genetic maps were constructed using double-digest restriction site-associated DNA-seq and simple sequence repeat markers. The map of 'Bouche de Betizac' consisted of 1459 loci and spanned 809.6 cM; the map of 'Madonna' consisted of 1089 loci and spanned 753.3 cM. In both maps, 12 linkage groups were identified. A single major QTL was recognized on the 'Bouche de Betizac' map, explaining up to 67-69% of the phenotypic variance of the resistance trait (Rdk1). TheRdk1quantitative trait loci (QTL) region included 11 scaffolds and two candidate genes putatively involved in the resistance response were identified. This study will contribute toC. sativabreeding programs and to the study ofRdk1genes

μ1B, a novel adaptor medium chain expressed in polarized epithelial cells11The nucleotide sequences reported in this paper have been submitted to GenBank with accession numbers AF020797 (human μ1B) and AF067146 (mouse μ1B).

AbstractThe apical and basolateral plasma membrane domains of polarized epithelial cells contain distinct sets of integral membrane proteins. Biosynthetic targeting of proteins to the basolateral plasma membrane is mediated by cytosolic tail determinants, many of which resemble signals involved in the rapid endocytosis or lysosomal targeting. Since these signals are recognized by adaptor proteins, we hypothesized that there could be epithelial-specific adaptors involved in polarized sorting. Here, we report the identification of a novel member of the adaptor medium chain family, named μ1B, which is closely related to the previously described μ1A (79% amino acid sequence identity). Northern blotting and in situ hybridization analyses reveal the specific expression of μ1B mRNA in a subset of polarized epithelial and exocrine cells. Yeast two-hybrid analyses show that μ1B is capable of interacting with generic tyrosine-based sorting signals. These observations suggest that μ1B may be involved in protein sorting events specific to polarized cells

Adaptive changes in muscular performance and circulation by resistance training with regular cold application

Abstract (1) Sixteen male subjects participated in resistance training comprising three sets of 8-handgrip exercises at a workload that could be performed no more than eight times, three times a week for 6 weeks. Eight subjects immersed their experimental forearm in cold water (1071 1C) for 20 min following each training period, while the remaining eight served as controls. (2) Muscular endurance with rhythmic handgrips significantly (po0.01) increased in both groups after the training period with a non-significant difference between groups. The relative diameter of ultrasonographyevaluated brachial artery failed to increase in the immersion group despite a significant increase (po0.05) of that in the control group after training. (3) Regular post-exercise cold application might attenuate the improvement in muscular endurance, possibly in association with reduced vascular remodeling.

Location of chlorogenic acid biosynthesis pathway and polyphenol oxidase genes in a new interspecific anchored linkage map of eggplant

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