Effects of 15-Acetyl-deoxynivalenol (15-ADON) and Diacetoxyscirpenol (DAS) Mycotoxins on Tribolium castaneum

Two major threats to stored products in the United States and throughout the world are stored product insects and contamination from mycotoxins, which are secondary metabolites produced by fungi, such as Fusarium spp. (Glenn, 2007). Although stored product insects are not associated with negative health impacts when consumed by humans or animals, mycotoxins can negatively impact fertility, reproductive health, growth and development, particularly in livestock (Brake, 1999). Unfortunately, it is difficult to remove mycotoxins from contaminated products and most products have to be destroyed. However, stored product insects routinely feed on products contaminated by mold and may posses detoxification enzymes that could be exploited by the food industry to degrade mycotoxins. To determine whether Tribolium castaneum (red flour beetles) may have resistance to mycotoxins commonly encountered in stored products, such as 15-acetyl-deoxynivalenol (15-ADON) and diacetoxyscirpenol (DAS), we performed bioassays using 10-fold serial dilutions of both purified toxins independently and measured life history parameters, including mortality rates, growth rates, and progeny production. These parameters were compared to insects fed on a control diet to determine whether mycotoxins negatively impacted red flour beetle adults. This allows for an understanding of how individual mycotoxins influence the insects rather than their combinations seen in naturally contaminated mold (Guo, 2014).The results showed no significant impact on any of the life history parameters from the 15-ADON mycotoxin; however, the DAS showed a significant impact on growth rates and progeny production. Furthering the study of the resistance of red flour beetles to mycotoxins may allow us to discover novel enzymes that could be used to degrade mycotoxins contaminating grain, allowing it to be used as animal food and reducing post-harvest losses

Population dynamics and resource utilization of the lesser grain borer, Rhyzopertha dominica (F.)

Master of ScienceDepartment of EntomologyKun Yan ZhuGenomic tools can provide important insights into the biology, dispersal, and feeding habits of insects whose behavior is difficult to monitor in the field, including stored product insects that primarily attack dried stored commodities and disperse throughout different agricultural landscapes where they may feed on alternate food resources. The lesser grain borer, Rhyzopertha dominica (Coleoptera: Bostrichidae), is a cosmopolitan pest that primarily attacks stored grain, but can be found in prairie landscapes despite the lack of primary food hosts in these natural locations. The presence of R. dominica in natural landscapes surrounding grain storage structures suggests that there could be interactions between individuals that colonize these habitats. In addition, lab studies have shown that this insect can feed and develop on alternative food hosts found in prairie landscapes. This thesis investigates the local interactions between populations of R. dominica at grain storage facilities and a nearby tallgrass prairie over the course of three field seasons using population genomics and dietary habits of R. dominica from two different tallgrass prairies (Nine Mile Prairie, Lincoln, NE and Konza Prairie, Manhattan, KS) using molecular gut content analysis . The population structure of R. dominica was examined by generating single nucleotide polymorphisms for individuals over three years to determine the interactions between insects caught in a large-scale grain elevator, a research flour mill, and a native tallgrass prairie. All three locations were located within 10 miles of one another. Heavy admixture was observed between the three locations across all three years surveyed, and location, field season, and the interaction of these two variables failed to explain the majority of the variation in genotypic diversity found in this species. In fact, more variation was observed among insects caught within a single location relative to insects collected from different locations. The most divergent populations were observed in the 2019 field season, likely due to the high amounts of rainfall observed and the lower number of individuals caught during this field season. The population of insects caught in the flour mill was also the most dissimilar to the flour mill and the prairies, which can be attributed to the strict guidelines for pest prevention in these types of facilities. The heavy admixture observed between the three locations, coupled with the low genetic variation between the locations, suggests significant interactions between these populations and indicates that R. dominica may be able to migrate between sources of grain and natural landscapes. To identify gut contents of R. dominica from Konza Prairie and Nine Mile Prairie, beetles were collected during their active flight season and plant-specific rbcL primers were used to detect and taxonomically classify plant DNA found inside the insect guts. Overall, we were able to identify 57 unique plant sequences between the two locations and identify 27 different plant species within their guts. While some individuals at both locations had recently fed on stored product commodities, products derived from these hosts were in low abundance. The most common and abundant taxon found in guts of insects caught in both locations was classified as Thinospyrum ponticum, which is known as tall wheatgrass. Several other plant species that are native to both the Konza and Nine Mile Prairies were identified, suggesting that R. dominica is able to exploit natural resources. The results from both studies highlight that R. dominica can exploit natural resources found in prairies and those that insects caught innatural landscapes near grain storage facilities interact with one another. These results contribute an increase in the understanding of the population dynamics of R. dominica between grain storage and the natural environment at a local scale, as well as their resource utilization. Previous studies have shown that populations in grain storage facilities can rebound quickly after fumigation and that insects in the surrounding landscape may serve as source populations. Our study confirms that insects from grain storage facilities and flour mills interact with those found in adjacent habitats. Therefore, we can use these results to better inform pest management and prevention of infestations by accounting for beetles that migrate from natural landscapes. Future work should assess gut content structure of R. dominica found in grain storage in comparison to those caught in landscapes, as well as assess genetic population structures across other location types and systems to gain further insights into their movement and migration

Power Sector Reforms and the Poor in Vietnam

The high level of electricity access across Vietnam means that large numbers of the poor have connections and therefore have the potential to be impacted by changes to tariffs and service levels. An estimated 98 percent of households were electrified by 2008, including 99 percent in urban and 97 percent in rural areas. Access to electricity is high even among Vietnam’s poorest households: in 1998, less than half of the poorest ten percent of households (bottom decile) used electricity, compared with 88 percent in 2008. While most of the poor in Vietnam are low consumers of electricity, so are many of the non-poor. In 2008, 65 percent of all households consumed less than 100 kWh/month, including 91 percent of poor urban households and 99 percent of poor rural households. Thus most of the electricity consumed by the poor was subsidized under the pre-2009 IBT lifeline. But so was the consumption of many of the non-poor: in 2008, only 14 percent of households in Vietnam lived below the poverty line. Moving to a lower lifeline threshold reduces leakages albeit at some cost to the poor: 30 percent of households consume less than 50 kWh/month, including 60 percent of poor urban households and 78 percent poor rural households. Despite the tariff increases, electricity remains remarkably affordable to residential consumers in Vietnam. In 2008, households in poorest 10% of the population paid on average 2.9 percent of total cash expenditures for electricity. In contrast, the wealthiest 10 percent of households paid 3.6 percent. And the share of total household spending taken by electricity has been falling in recent years despite rising consumption; the real price of electricity (adjusted for inflation) has been falling

Power Sector Reforms and the Poor in Vietnam

The high level of electricity access across Vietnam means that large numbers of the poor have connections and therefore have the potential to be impacted by changes to tariffs and service levels. An estimated 98 percent of households were electrified by 2008, including 99 percent in urban and 97 percent in rural areas. Access to electricity is high even among Vietnam’s poorest households: in 1998, less than half of the poorest ten percent of households (bottom decile) used electricity, compared with 88 percent in 2008. While most of the poor in Vietnam are low consumers of electricity, so are many of the non-poor. In 2008, 65 percent of all households consumed less than 100 kWh/month, including 91 percent of poor urban households and 99 percent of poor rural households. Thus most of the electricity consumed by the poor was subsidized under the pre-2009 IBT lifeline. But so was the consumption of many of the non-poor: in 2008, only 14 percent of households in Vietnam lived below the poverty line. Moving to a lower lifeline threshold reduces leakages albeit at some cost to the poor: 30 percent of households consume less than 50 kWh/month, including 60 percent of poor urban households and 78 percent poor rural households. Despite the tariff increases, electricity remains remarkably affordable to residential consumers in Vietnam. In 2008, households in poorest 10% of the population paid on average 2.9 percent of total cash expenditures for electricity. In contrast, the wealthiest 10 percent of households paid 3.6 percent. And the share of total household spending taken by electricity has been falling in recent years despite rising consumption; the real price of electricity (adjusted for inflation) has been falling

Low dose inflammatory potential of silica particles in human-derived THP-1 macrophage cell culture studies - Mechanism and effects of particle size and iron.

Silica and iron are major constituents in ambient particulate matter, and iron is a common impurity in many engineered nanomaterials. The purpose of this work was to determine the pro-inflammatory and other biological effects and mechanism of particle size and iron presence under low dose, non-cytotoxic conditions that are likely to approximate actual exposure levels, in contrast with higher dose studies in which cytotoxicity occurs. Specifically, human-derived THP-1 macrophages were exposed to 1 μg/ml of pristine and iron-coated 50 nm and 2 μm engineered silica nanoparticles. Particles were first characterized for size, size distribution, surface area, iron concentration, phase and aggregation in cell culture media. Then, biological assays were conducted to determine a non-lethal dose used in subsequent experiments. Superoxide production, lipid peroxidation, and increased pro-inflammatory cytokine (TNF-α and IL-1β) mRNA expression were measured as a function of particle size and iron presence. Smaller particle size and the presence of iron increased superoxide production, lipid peroxidation, and the induction of pro-inflammatory cytokine mRNA expression. Separate addition of an iron-chelator, a scavenger of superoxide and hydrogen peroxide, and an inhibitor of phosphatidylcholine specific phospholipase C (PC-PLC), suppressed the increase in cytokine mRNA expression. Furthermore, free iron itself showed none of the aforementioned effects. The results highlight the importance of particle size and iron in lung inflammation for both natural and engineered nanomaterials, under low dose, non-toxic conditions, and support the role of an oxidant, lipid peroxidation and PC-PLC dependent inflammatory mechanism

Selection of DNA nanoparticles with preferential binding to aggregated protein target.

High affinity and specificity are considered essential for affinity reagents and molecularly-targeted therapeutics, such as monoclonal antibodies. However, life's own molecular and cellular machinery consists of lower affinity, highly multivalent interactions that are metastable, but easily reversible or displaceable. With this inspiration, we have developed a DNA-based reagent platform that uses massive avidity to achieve stable, but reversible specific recognition of polyvalent targets. We have previously selected these DNA reagents, termed DeNAno, against various cells and now we demonstrate that DeNAno specific for protein targets can also be selected. DeNAno were selected against streptavidin-, rituximab- and bevacizumab-coated beads. Binding was stable for weeks and unaffected by the presence of soluble target proteins, yet readily competed by natural or synthetic ligands of the target proteins. Thus DeNAno particles are a novel biomolecular recognition agent whose orthogonal use of avidity over affinity results in uniquely stable yet reversible binding interactions

The cyclin-dependent kinase inhibitor Orysa;KRP1 plays an important role in seed development of rice

Kip-related proteins (KRPs) play a major role in the regulation of the plant cell cycle. We report the identification of five putative rice (Oryza sativa) proteins that share characteristic motifs with previously described plant KRPs. To investigate the function of KRPs in rice development, we generated transgenic plants overexpressing the Orysa; KRP1 gene. Phenotypic analysis revealed that overexpressed KRP1 reduced cell production during leaf development. The reduced cell production in the leaf meristem was partly compensated by an increased cell size, demonstrating the existence of a compensatory mechanism in monocot species by which growth rate is less reduced than cell production, through cell expansion. Furthermore, Orysa; KRP1 overexpression dramatically reduced seed filling. Sectioning through the overexpressed KRP1 seeds showed that KRP overproduction disturbed the production of endosperm cells. The decrease in the number of fully formed seeds was accompanied by a drop in the endoreduplication of endosperm cells, pointing toward a role of KRP1 in connecting endocycle with endosperm development. Also, spatial and temporal transcript detection in developing seeds suggests that Orysa; KRP1 plays an important role in the exit from the mitotic cell cycle during rice grain formation

Targeted DNA methylation of endogenous promoters and the CMV promoter entails distinct and subsequent histone modification changes in CHO cells

Please click Additional Files below to see the full abstract