Biochemical, Molecular, and Genetic Analysis of Cell Wall Biogenesis and Carbohydrate Accumulation of the Stem During the Phenology of Sorghum bicolor

Alternative sources of fuel such as bioethanol offer benefits such as energy independence and stability, reduction in green house gas emissions, and are a renewable resource. The C4 grasses are large contributors of fermentable carbohydrates for bioenthanol production. However, fermentable carbohydrate yields from grass stems have plateaued in recent years. Transgenic manipulation may provide solutions to engineering increased nonstructural carbohydrate yields, increase cell wall digestibility and accessibility, and reduce agricultural input costs. Sorghum bicolor is a prime candidate as a biofuel feedstock, but lacks the molecular characterization essential for transgenic manipulation. Therefore, the focus of this research was to conduct a comprehensive characterization of the biochemical, molecular and genetic dynamics of nonstructural carbohydrate accumulation and cell wall biogenesis in the sorghum stem. To facilitate this investigation a high biomass accumulating elite sweet sorghum named Della was selected as a model since this sorghum accumulates high biomass and therefore closely approximates a sweet energy sorghum. Analysis of dry biomass accumulation revealed that Della invests heavily in stem growth starting at the beginning of the vegetative phase and ending at anthesis, subsequently accumulating sugar in its stem during flowering. To identify genes involved in cell wall biogenesis and carbohydrate accumulation, a time-course of Della internode transcriptome dynamics was conducted beginning at floral initiation and ending ~20 days after grain maturity encompassing the time course of carbohydrate accumulation in the stem. This analysis identified candidate genes involved in cell wall biosynthetic processes and nonstructural carbohydrate partitioning and accumulation were identified. Della synthesizes starch in its stem after anthesis. Since starch is more stable than sucrose, has favorable osmotic properties, and is already present in the sorghum stem, this pathway was selected as the focus for further analysis. This analysis revealed candidate genes that will be useful for future transgenic studies. Additionally, stem biomass from Della was observed to have accumulated starch up to ~15% of the total stem dry biomass and ~30% of total nonstructural carbohydrate content. Therefore, utilization of existing starch stores in sorghum stem biomass would increase fermentable carbohydrate yield significantly. Lastly, genetic analysis of the grain*sweet sorghum cross RTx436*Della identified loci that underlie stem volume traits when mapping quantitative trait loci for internode carbohydrate content. This suggests that stem carbohydrate concentration reached a maximum level and was limited by volume. Also, carbohydrate was found to be correlated with internode volume and not stem juiciness and leaf area. Finally, radiation use efficiency analysis revealed that at certain points during development the canopy may be underutilized and that increasing the sink strength of the sorghum stem may benefit nonstructural carbohydrate yield

The toxicity of potentially toxic elements (Cu, Fe, Mn, Zn and Ni) to the cnidarian <i>Hydra attenuata</i> at environmentally relevant concentrations

The domestic, agricultural, industrial, technological and medical applications of potentially toxic elements (PTEs) have led to global pollution in all environments. In this study, the cnidarian Hydra attenuata was exposed individually and to a mixture of 5 metals (copper, iron, manganese, zinc and nickel) at environmentally relevant concentrations (1×) within the Clyde estuary, Scotland and incremental concentrations ranging from 0.0001× to 1000×. Toxicity was investigated using morphology, attachment, hydranth number and feeding behaviour as endpoints. When exposed individually, Cu, Mn and Fe significantly reduced Hydra morphology, feeding and attachment at environmentally relevant concentrations. Hydra mortality was measured, having an LC50 of 0.045× (for the environmentally relevant mixture of metals) and Cu 0.5 mg/l, Fe 3 mg/l, Mn 2 mg/l, Zn 0.1 mg/l, Ni 0.5 mg/l for each element exposed individually. The PTE mixture incurred a significant decrease (p ≤ 0.05) in morphology at 0.0001×, with 100% mortality at 0.1× (containing a concentration of Cu 0.05 mg/l, Fe 0.3 mg/l, Mn 0.2 mg/l, Zn 0.01 mg/l, Ni 0.05 mg/l) and a toxicity threshold (TT) of 0.000005×. Both copper and iron when exposed individually to the concentration of their respective metals found in the environment resulted in 100% mortality for all Hydra exposed. These results indicate that the PTE mixture (including the individual concentrations of copper, iron, manganese and nickel) could potentially prove significantly toxic to the aquatic environment

The Relationship of Faculty Demographics and Attitudes toward Technology Integration

Stakeholders in a midsized rural high school district were concerned that faculty failure to integrate educational technologies into instruction was adversely affecting student performance as measured by recent state mandated test scores. The purpose of this study was to determine if relationships existed between faculty age, gender, tenure, and overall attitude toward technology, and the implementation of technology into classroom instruction. Dewey\u27s and Knowles\u27 theories of adult learning were used as theoretical frameworks because they emphasize the practical application of knowledge in the transfer of learning. The research design was a one-time cross-sectional survey of teachers within the district. The data were collected using the Levels of Technology Implementation survey extended to include 5 additional questions about attitude towards technology developed using existing literature and consultation with experts. The convenience sample was comprised of 103 volunteer respondents at 3 midsized rural high schools. Analysis of the data utilized Pearson\u27s correlation coefficients, independent samples t-tests, ANOVAs, and ANCOVAs. Findings indicated that technology implementation in classroom instruction for this group is generally deficient. No significant relationships between faculty age, gender, and tenure and technology implementation existed, but attitude toward technology proved to be a significant factor for increased technology implementation into classroom instruction. These findings led to the creation of a professional development program to increase the impact of technology on the transfer of learning. Increasing faculty expertise in implementing instructional technology into classroom instruction will lead to greater innovation in the classroom and improved student outcomes

Social structure and the maintenance of biodiversity

Traditional ecological models assume well-mixed populations, where all members are equally likely to interact with one another. These models have been used successfully to explain competitive interactions; however, positive interactions such as intraspecific cooperation and interspecific facilitation cannot readily be captured. Previous work has highlighted the importance of spatial structure in explaining these behaviors as well as its role in maintaining biodiversity. These spatial structures have frequently been modeled using lattices, where all organisms have an equal number of interactions. Although these models capture the spatiality of interactions, natural populations are unlikely to follow such rigid patterns. There has been little work investigating the dynamics of populations with levels of social interactions that occur between these two extremes. In this work, we investigate the dynamics of a 3-strategy nontransitive system in populations with different social structures. We first describe how extending the neighborhood of interactions in traditional lattice models diminishes a population’s ability to maintain diversity. Populations are then moved to graphs where interactions are limited to cells within a defined distance of each other in Cartesian space. This method allows for a more fine-grained examination of the effects that increasing interactions have on maintaining diversity. Finally, we examine small world topologies and find that the introduction of random edges into the graph quickly disrupts the maintenance of diversity

Session B1: Lessons Learned from Tropical Storm Irene 2.0: How Flood Resiliency Benefits of Stream Simulation Designs Are Changing Policy within the U.S.

Abstract Stream simulation design is a geomorphic, engineering, and ecologically-based approach to designing road-stream crossings that creates a natural and dynamic channel through the crossing structure similar in dimensions and characteristics to the adjacent, natural channel, allowing for unimpeded passage of aquatic organisms, debris, and water during various flow conditions, including floods. A retrospective case study of the survival and failure of road-stream crossings was conducted in the upper White River watershed and the Green Mountain National Forest in Vermont following record flooding from Tropical Storm Irene in August 2011. Damage was largely avoided at two road-stream crossings where stream simulation design was implemented, and extensive at multiple road-stream crossings constructed using traditional undersized, hydraulic designs. Cost analyses suggest that relatively modest increases in initial investment to implement stream simulation designs yield substantial societal and economic benefits. Numerous other examples across the country of stream simulation designs surviving large flood events underscore these benefits. Four years after the historic Irene flood event, policy changes at state and federal levels across the U.S. suggest that the flood resiliency of culverts is gaining momentum as a policy driver amid growing public sensitivity to climate change risks and the importance of restoring ecological connectivity and protecting investments in transportation infrastructure

Sustainable Drag Reduction in Turbulent Taylor-Couette Flows by Depositing Sprayable Superhydrophobic Surfaces

We demonstrate a reduction in the measured inner wall shear stress in moderately turbulent Taylor-Couette flows by depositing sprayable superhydrophobic microstructures on the inner rotor surface. The magnitude of reduction becomes progressively larger as the Reynolds number increases up to a value of 22% at Re=8.0×10[superscript 4]. We show that the mean skin friction coefficient C[subscript f] in the presence of the superhydrophobic coating can be fitted to a modified Prandtl–von Karman–type relationship of the form (C[subscript f]/2)[[superscript -1/2] = Mln (Re(C[subscript f]/2)[[superscript 1/2]) + N + (b/Δr)Re(C[subscript f]/2)[superscript 1/2] from which we extract an effective slip length of b ≈ 19  μm. The dimensionless effective slip length b[superscript +] = b/δ[subscript ν], where δ[subscript ν] is the viscous length scale, is the key parameter that governs the drag reduction and is shown to scale as b[[superscript +] ~ Re[superscript 1/2] in the limit of high Re.United States. Office of Naval Research (Contract 3002453814

The Sorghum bicolor reference genome: improved assembly, gene annotations, a transcriptome atlas, and signatures of genome organization.

Sorghum bicolor is a drought tolerant C4 grass used for the production of grain, forage, sugar, and lignocellulosic biomass and a genetic model for C4 grasses due to its relatively small genome (approximately 800&nbsp;Mbp), diploid genetics, diverse germplasm, and colinearity with other C4 grass genomes. In this study, deep sequencing, genetic linkage analysis, and transcriptome data were used to produce and annotate a high-quality reference genome sequence. Reference genome sequence order was improved, 29.6&nbsp;Mbp of additional sequence was incorporated, the number of genes annotated increased 24% to 34&nbsp;211, average gene length and N50 increased, and error frequency was reduced 10-fold to 1 per 100&nbsp;kbp. Subtelomeric repeats with characteristics of Tandem Repeats in Miniature (TRIM) elements were identified at the termini of most chromosomes. Nucleosome occupancy predictions identified nucleosomes positioned immediately downstream of transcription start sites and at different densities across chromosomes. Alignment of more than 50 resequenced genomes from diverse sorghum genotypes to the reference genome identified approximately 7.4&nbsp;M single nucleotide polymorphisms (SNPs) and 1.9&nbsp;M indels. Large-scale variant features in euchromatin were identified with periodicities of approximately 25&nbsp;kbp. A transcriptome atlas of gene expression was constructed from 47 RNA-seq profiles of growing and developed tissues of the major plant organs (roots, leaves, stems, panicles, and seed) collected during the juvenile, vegetative and reproductive phases. Analysis of the transcriptome data indicated that tissue type and protein kinase expression had large influences on transcriptional profile clustering. The updated assembly, annotation, and transcriptome data represent a resource for C4 grass research and crop improvement

Resource abundance promotes the evolution of public goods cooperation

Understanding the evolution of cooperation as part of an evolutionary stable strategy (ESS) is a difficult problem that has been the focus of much work. The associated costs of cooperation may lower the fitness of an organism below that of its non-cooperating counterpart, allowing the more fit or-ganism to persist and outcompete the cooperator. Insight into these behaviors can help provide a better understand-ing of many aspects of the natural world, as well as provide future avenues for fighting disease. In this study, we use digital evolution to examine how the abundance of a required resource affects the coopera-tive production of a public good in an adverse environment. Evolutionary computation is an excellent tool for examining these problems, as it offers researchers complete access to or-ganisms and total control over their environment. We find that stable cooperation can occur in otherwise competitive environments at discrete levels corresponding to the avail-ability of a required resource. When resource levels are low, organisms focus solely on competitive behaviors. However, once resource levels cross a critical threshold, cooperation persists in populations. Further, this cooperation occurs in patches, where it is most likely to benefit relatives. Finally, we find that in some cases this cooperative behavior allows organisms to increase their competitive abilities as well