The effect of reduced chromatin gene expression on an epigenetically regulated maize gene

Abstract only availableIn virtually all eukaryotic organisms, not just plants, genes are regulated at the level of chromatin. In a genomics approach to understand how expression of a gene can be regulated by its chromatin configuration, a series of maize mutants in which chromatin gene expression has been knocked down by RNA interference are being analyzed. Mutants of three different types of chromatin genes, which all are thought to have normal roles in gene silencing, were examined. The maize gene chr101 is orthologous to the Arabidopsis gene DDM1, which codes for an ATPase-dependent chromatin remodeling protein responsible for maintaining DNA methylation and gene silencing patterns. The maize genes dmt101, dmt102, and dmt106 show sequence homology to the Arabodopsis genes MET1, CMT1, and DRM3, respectively, all of which code for DNA methyltransferases. The maize mbd genes show sequence homology to the Arabodopsis AtMBD genes, which code for methyl-CpG-binding domain proteins responsible for binding specifically to methylated DNA and recruiting histone deacetylases, which aid in tightening chromatin structure. To look at the effect of reduced chromatin gene expression, plants carrying transgenes targeting chr, dmt, or mbd genes were crossed to a line carrying a gene that acts as a reporter for chromatin-level regulation. The reporter, Pl-Blotched, activates synthesis of purple anthocyanin pigments to produce a variegated phenotype that is correlated with closed chromatin and a distinct pattern of DNA methylation. Mutations in genes that are necessary for maintaining a closed chromatin configuration--like chr, dmt, and mbd genes--may lead to increased Pl-Blotched expression, which should be evident phenotypically as higher anthocyanin levels. To test this idea, I measured pigment levels in plants carrying chromatin-gene mutations. Increased pigmentation in the transgenic plants will provide evidence that the targeted genes play a role in regulating Pl-Blotched.Arts & Sciences Undergraduate Research Mentorship Progra

Maize brace root formation and correlation with juvenile nodes and tassel structure [abstract]

Abstract only availableGlobal warming causing changes in weather patterns is making drought a more frequent occurrence. Drought is a major limiting factor of maize production worldwide. To maintain high production levels, it is important to identify maize lines which are tolerant to water-stress conditions. A significant trait in drought tolerance is an extensive root system. Root systems in maize are composed of not only below ground roots but also above ground roots. These above ground roots are commonly known as brace roots, and they function to keep the plant upright and provide a surface for nutrient and water uptake and gas exchange. Preliminary studies have demonstrated correlations between brace root architecture and tassel branching. There is a negative correlation between central spike length and number of nodes with brace roots. Studies also indicate brace roots emerge from juvenile nodes The objective of this study is to examine these relationships on a set of 25 diverse maize lines. Leaf traits were measured to identify juvenile, transitional, and adult leaves. These data will be used to determine if juvenile nodes give rise to brace roots. Various measurements of tassel structure will be gathered and statistically analyzed for relationships between tassel traits and brace root architecture. Examining tassel structure and juvenile node number may help in the selection of maize lines with an increased number of brace roots which allow for adaptation to water-stressed environments

Characterization of a recombinant inbred line population for quantitative trait locus mapping

Abstract only availableEukaryotes can regulate gene expression by epigenetic mechanisms at the chromatin level. One epigenetically regulated gene in maize is Pl1-Blotched, an allele of purple plant1, which activates anthocyanin pigment production. Normally, Pl1-Blotched leads to a variegated pattern of pigmentation, but its pigment level can be increased by a modifier called Suppressor of plant blotching (Spb). At the molecular level, Spb alters the chromatin packing of Pl1-Blotched, leading to less tightly packed chromatin and higher gene expression. The genetic identity of Spb is not yet known, although preliminary results indicate the Spb-enhanced pigment phenotype is a quantitative trait. As a step toward isolating the genes for Spb, a mapping population of Recombinant Inbred Lines (RILs) was generated by inbreeding the progeny of an F2 derived from a cross of Pl1-Blotched with Spb to a less pigmented Pl1-Blotched stock. Genotypes were determined for 188 RILs using microsatellite or simple sequence repeat (SSR) markers. RILs were evaluated for residual heterozygosity, breakpoint locations, and heterozygous chromosomal positions. A map was created and will be used as the foundation for mapping Spb and for estimating the heritability of the Spb phenotype.NSF-REU Program in Biological Sciences & Biochemistr

Does Practice Make Perfect? A Randomized Control Trial of Behavioral Rehearsal on Suicide Prevention Gatekeeper Skills

Suicide is the third leading cause of death among 10-24-year-olds and the target of school-based prevention efforts. Gatekeeper training, a broadly disseminated prevention strategy, has been found to enhance participant knowledge and attitudes about intervening with distressed youth. Although the goal of training is the development of gatekeeper skills to intervene with at-risk youth, the impact on skills and use of training is less known. Brief gatekeeper training programs are largely educational and do not employ active learning strategies such as behavioral rehearsal through role play practice to assist skill development. In this study, we compare gatekeeper training as usual with training plus brief behavioral rehearsal (i.e., role play practice) on a variety of learning outcomes after training and at follow-up for 91 school staff and 56 parents in a school community. We found few differences between school staff and parent participants. Both training conditions resulted in enhanced knowledge and attitudes, and almost all participants spread gatekeeper training information to others in their network. Rigorous standardized patient and observational methods showed behavioral rehearsal with role play practice resulted in higher total gatekeeper skill scores immediately after training and at follow-up. Both conditions, however, showed decrements at follow-up. Strategies to strengthen and maintain gatekeeper skills over time are discussed

Diffusion of Immunoglobulin G in Shed Vaginal Epithelial Cells and in Cell-Free Regions of Human Cervicovaginal Mucus

Human cervicovaginal mucus (CVM) is a viscoelastic gel containing a complex mixture of mucins, shed epithelial cells, microbes and macromolecules, such as antibodies, that together serve as the first line of defense against invading pathogens. Here, to investigate the affinity between IgG and different mucus constituents, we used Fluorescence Recovery After Photobleaching (FRAP) to measure the diffusion of IgG in fresh, minimally modified CVM. We found that CVM exhibits substantial spatial variations that necessitate careful selection of the regions in which to perform FRAP. In portions of CVM devoid of cells, FRAP measurements using different IgG antibodies and labeling methods consistently demonstrate that both exogenous and endogenous IgG undergo rapid diffusion, almost as fast as in saline, in good agreement with the rapid diffusion of IgG in mid-cycle endocervical mucus that is largely devoid of cells. This rapid diffusion indicates the interactions between secreted mucins and IgG must be very weak and transient. IgG also accumulated in cellular debris and shed epithelial cells that had become permeable to IgG, which may allow shed epithelial cells to serve as reservoirs of secreted IgG. Interestingly, in contrast to cell-free regions of CVM, the diffusion of cell-associated IgG was markedly slowed, suggesting greater affinity between IgG and cellular constituents. Our findings contribute to an improved understanding of the role of IgG in mucosal protection against infectious diseases, and may also provide a framework for using FRAP to study molecular interactions in mucus and other complex biological environments

Diffusion of a Peer-Led Suicide Preventive Intervention Through School-Based Student Peer and Adult Networks

Background: Peer-led interventions have been applied to prevent various health behavior problems and may be an important complement to individual-level suicide prevention approaches. Sources of Strength trains student “peer leaders” in secondary schools to conduct prevention activities that encourage other students to build healthy social bonds and strengthen help-seeking norms. Prior work examining diffusion of peer-led programs has focused on youths' closeness to peer leaders but minimally on other factors such as connections to adults and suicidal behavior.Methods: We examined implementation and dissemination of Sources of Strength in 20 schools. Over 1 year 533 students were trained as peer leaders and 3,730 9th−12th graders completed baseline surveys assessing friendships and adults at school, and suicidal thoughts/behaviors; and end-of-year surveys reporting intervention exposure: viewed poster/video, attended presentation, direct peer communication, and activity participation. Chi-square tests compared exposure rates by student and network characteristics. Multi-level logistic regression models tested predictors of exposure across individual and school-level characteristics.Results: Exposure to the intervention varied greatly by school and by individual student characteristics and network position. Training more peer leaders increased school-wide exposure for all modalities except presentation (Bs 0.06–0.10, p's < 0.05). In multivariate models, exposure was consistently higher for students closer to peer leaders in the friendship network (ORs 1.13–1.54, p's < 0.05) and students who named more trusted adults (ORs 1.08–1.16, p's < 0.001); and lower for males (ORs 0.56–0.83, p's < 0.05). In multivariate models, training more students as peer leaders predicted exposure to poster-video and direct peer communication in larger schools (OR = 3.34 and 2.87, respectively). Network characteristics influenced exposure similarly for students with suicidal thoughts and behaviors.Discussion: Our findings confirm prior work showing the importance of personal affiliations to peer leaders and natural networks as a medium for diffusion of peer-led prevention efforts. We build on that work by showing independent effects of closeness to adults at school and number of peer leaders trained. There is a need to strategically select peer leaders to maximize closeness to students school-wide, particularly in larger schools. Additional work is required for Sources of Strength to devise messaging strategies to engage males and students isolated from adults at school

Australasian emergency nurses\u27 willingness to attend work in a disaster: a survey

Abstract not availablePaul Arbon, Jamie Ranse, Lynette Cusack, Julie Considine, Ramon Z. Shaban, Richard J. Woodman, Laura Bahnisch, Mayumi Kako, Karen Hammad, Belinda Mitchel

Physical and Genetic Structure of the Maize Genome Reflects Its Complex Evolutionary History

Maize (Zea mays L.) is one of the most important cereal crops and a model for the study of genetics, evolution, and domestication. To better understand maize genome organization and to build a framework for genome sequencing, we constructed a sequence-ready fingerprinted contig-based physical map that covers 93.5% of the genome, of which 86.1% is aligned to the genetic map. The fingerprinted contig map contains 25,908 genic markers that enabled us to align nearly 73% of the anchored maize genome to the rice genome. The distribution pattern of expressed sequence tags correlates to that of recombination. In collinear regions, 1 kb in rice corresponds to an average of 3.2 kb in maize, yet maize has a 6-fold genome size expansion. This can be explained by the fact that most rice regions correspond to two regions in maize as a result of its recent polyploid origin. Inversions account for the majority of chromosome structural variations during subsequent maize diploidization. We also find clear evidence of ancient genome duplication predating the divergence of the progenitors of maize and rice. Reconstructing the paleoethnobotany of the maize genome indicates that the progenitors of modern maize contained ten chromosomes