Genomics-enabled analysis of the emergent disease cotton bacterial blight.

Cotton bacterial blight (CBB), an important disease of (Gossypium hirsutum) in the early 20th century, had been controlled by resistant germplasm for over half a century. Recently, CBB re-emerged as an agronomic problem in the United States. Here, we report analysis of cotton variety planting statistics that indicate a steady increase in the percentage of susceptible cotton varieties grown each year since 2009. Phylogenetic analysis revealed that strains from the current outbreak cluster with race 18 Xanthomonas citri pv. malvacearum (Xcm) strains. Illumina based draft genomes were generated for thirteen Xcm isolates and analyzed along with 4 previously published Xcm genomes. These genomes encode 24 conserved and nine variable type three effectors. Strains in the race 18 clade contain 3 to 5 more effectors than other Xcm strains. SMRT sequencing of two geographically and temporally diverse strains of Xcm yielded circular chromosomes and accompanying plasmids. These genomes encode eight and thirteen distinct transcription activator-like effector genes. RNA-sequencing revealed 52 genes induced within two cotton cultivars by both tested Xcm strains. This gene list includes a homeologous pair of genes, with homology to the known susceptibility gene, MLO. In contrast, the two strains of Xcm induce different clade III SWEET sugar transporters. Subsequent genome wide analysis revealed patterns in the overall expression of homeologous gene pairs in cotton after inoculation by Xcm. These data reveal important insights into the Xcm-G. hirsutum disease complex and strategies for future development of resistant cultivars.

Effect of magnification loupes on dental hygiene student posture.

The chair-side work posture of dental hygienists has long been a concern because of health-related problems potentially caused or exacerbated by poor posture. The purpose of this study was to investigate if using magnification loupes improved dental hygiene students' posture during provision of treatment. The treatment chosen was hand-scaling, and the effect of the timing of introduction of the loupes to students was also examined. Thirty-five novice dental hygiene students took part in the study. Each student was assessed providing dental hygiene care with and without loupes, thus controlling for innate differences in natural posture. Students were randomized into two groups. Group one used loupes in the first session and did not use them for the second session. Group two reversed this sequence. At the end of each session, all students were videotaped while performing scaling procedures. Their posture was assessed using an adapted version of Branson et al.'s Posture Assessment Instrument (PAI). Four raters assessed students at three time periods for nine posture components on the PAI. A paired t-test compared scores with and without loupes for each student. Scores showed a significant improvement in posture when using loupes (p<0.0001), and these improvements were significantly more pronounced for students starting loupes immediately on entering the program compared with students who delayed until the second session (p<0.1). These results suggest a significant postural benefit is realized by requiring students to master the use of magnification loupes as early as possible within the curriculum.