BackgroundMerkel cell polyomavirus (MCPyV) has been detected in approximately 75% of patients with the rare skin cancer Merkel cell carcinoma. We investigated the prevalence of antibodies against MCPyV in the general population and the association between these antibodies and Merkel cell carcinoma.MethodsMultiplex antibody-binding assays were used to assess levels of antibodies against polyomaviruses in plasma. MCPyV VP1 antibody levels were determined in plasma from 41 patients with Merkel cell carcinoma and 76 matched control subjects. MCPyV DNA was detected in tumor tissue specimens by quantitative polymerase chain reaction. Seroprevalence of polyomavirus-specific antibodies was determined in 451 control subjects. MCPyV strain–specific antibody recognition was investigated by replacing coding sequences from MCPyV strain 350 with those from MCPyV strain w162.ResultsWe found that 36 (88%) of 41 patients with Merkel cell carcinoma carried antibodies against VP1 from MCPyV w162 compared with 40 (53%) of the 76 control subjects (odds ratio adjusted for age and sex = 6.6, 95% confidence interval [CI] = 2.3 to 18.8). MCPyV DNA was detectable in 24 (77%) of the 31 Merkel cell carcinoma tumors available, with 22 (92%) of these 24 patients also carrying antibodies against MCPyV. Among 451 control subjects from the general population, prevalence of antibodies against human polyomaviruses was 92% (95% CI = 89% to 94%) for BK virus, 45% (95% CI = 40% to 50%) for JC virus, 98% (95% CI = 96% to 99%) for WU polyomavirus, 90% (95% CI = 87% to 93%) for KI polyomavirus, and 59% (95% CI = 55% to 64%) for MCPyV. Few case patients had reactivity against MCPyV strain 350; however, indistinguishable reactivities were found with VP1 from strain 350 carrying a double mutation (residues 288 and 316) and VP1 from strain w162.ConclusionInfection with MCPyV is common in the general population. MCPyV, but not other human polyomaviruses, appears to be associated with Merkel cell carcinoma.

With the development of genetic maps and the identification of the most-likely positions of quantitative trait loci (QTLs) on these maps, molecular markers for lodging resistance can be identified. Consequently, marker-assisted selection (MAS) has the potential to improve the efficiency of selection for lodging resistance in a breeding program. This study was conducted to identify genetic loci associated with lodging resistance, plant height and reaction to mycosphaerella blight in pea. A population consisting of 88 recombinant inbred lines (RILs) was developed from a cross between Carneval and MP1401. The RILs were evaluated in 11 environments across the provinces of Manitoba, Saskatchewan and Alberta, Canada in 1998, 1999 and 2000. One hundred and ninety two amplified fragment length polymorphism (AFLP) markers, 13 random amplified polymorphic DNA (RAPD) markers and one sequence tagged site (STS) marker were assigned to ten linkage groups (LGs) that covered 1,274 centi Morgans (cM) of the pea genome. Six of these LGs were aligned with the previous pea map. Two QTLs were identified for lodging resistance that collectively explained 58% of the total phenotypic variation in the mean environment. Three QTLs were identified each for plant height and resistance to mycosphaerella blight, which accounted for 65% and 36% of the total phenotypic variation, respectively, in the mean environment. These QTLs were relatively consistent across environments. The AFLP marker that was associated with the major locus for lodging resistance was converted into the sequence-characterized amplified-region (SCAR) marker. The presence or absence of the SCAR marker corresponded well with the lodging reaction of 50 commercial pea varieties.

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Amplified fragment length polymorphism (AFLP) marker system has had broad applications in biology. However, the anonymous AFLP markers are mainly amplified from non-coding regions, limiting their usefulness as a functional marker system. To take advantages of the traditional AFLP techniques, we propose substitution of a restriction enzyme that recognizes a restriction site containing ATG, called ATG-anchored AFLP (ATG-AFLP) analysis. In this study, we chose NsiI (recognizing ATGCAT) to replace EcoRI in combination with MseI to completely digest genomic DNA. One specific adaptor, one pre-selective primer and six selective amplification primers for the NsiI site were designed for ligation and PCR. Six NsiI and eight MseI primers generated a total of 1,780 ATG-AFLP fragments, of which 750 (42%) were polymorphic among four genotypes from two cultivated cotton species (Upland cotton, Gossypium hirsutum and Pima cotton, G. barbadense). The number of ATG-AFLP markers was sufficient to separate the four genotypes into two groups, consistent with their evolutionary and breeding history. Our results also showed that ATG-AFLP generated less number of total and polymorphic fragments per primer combination (2-3 vs. 4-5) than conventional AFLP within Upland cotton. Using a recombination inbred line (RIL) population, 62 polymorphic ATG-AFLP markers were mapped to 19 linkage groups with known chromosome anchored simple sequence repeat (SSR) markers. Of the nine ATG-AFLP fragments randomly chosen, three were found to be highly homologous to cotton cDNA sequences. An in-silico analysis of cotton and Arabidopsis cDNA confirmed that the ATG-anchored enzyme combination NsiI/MseI did generate more fragments than the EcoRI/MseI combination.