Quantitative trait loci for seminal root angle and number in the maize IBM population

Abstract only availableIn maize, seminal roots develop and the primary root system deteriorates as the plant matures. The seminal roots comprise the majority of the root system of the adult plant and give the plant stability against lodging. Because seminal roots are the primary means of water uptake in the adult plant, their development under drought conditions is vital. Previous research has suggested that seminal root angle and abscisic acid (ABA) level are correlated in maize. Additional research has shown that ABA levels are related to drought tolerance. This study focuses on identifying quantitative trait loci (QTL) that affect seminal root angle and the number of seminal roots entering the soil from each node. The QTL generated for seminal root angle and number per node can then be used to evaluate the relationship with drought tolerance. A set of 94 mapping lines from the intermated B73 x Mo17 (IBM) mapping population was used to measure the angle between the seminal root and the stalk. The number of seminal roots entering the soil from the first two nodes was measured as well. Molecular markers evenly distributed throughout the genome were used to run the QTL analysis using QTL Cartographer Version 1.16. The following QTL analyses were run: seminal root angle, number of roots entering soil from the first node above ground, and number of roots entering soil from the second node. Three QTL were found for seminal root angle, two QTL for the number of roots at the first node above ground, and three QTL for the number of roots at the second node above ground. These QTL positions were then compared to previously known QTL for drought tolerance and root traits.Plant Genomics Internship @ M

The will of Congress? Permissive regulation and the strategic use of labeling for the anti-influenza drug Relenza

Through an analysis of the FDA’s approval of the controversial anti-influenza drug Relenza (zanamivir), we interrogate distinct social scientific theories of pharmaceutical regulation. We investigate why, despite internal negative opinions and an Advisory Committee’s non-approval recommendation, the FDA approved Relenza in the late 1990s. Based on a close reading of FDA documents, we show how agency officials guided the manufacturer’s analyses and participated in constructing a tenuous argument for approval. We show how regulators may strategically design drug labels that can justify their permissive regulation. We consider the explanatory power of official accounts and alternative, partially overlapping, theories of pharmaceutical regulation in the Relenza case, and develop new insights into the institutional dynamics of regulator-industry relations. We find little or no evidence that the FDA was primarily driven by public health concerns, pressure from disease-based patient activism, or a consumerist and neoliberal regulatory logic, although some of these explanations provided managers with convenient rhetoric to rationalize their actions. Rather, we argue that the Relenza case highlights contradictions between a scientific culture at FDA, conducive to rigorous product evaluations, and the agency’s attempts to accommodate higher-level political (i.e. Congress) and industry demands conducive of permissive regulation – consistent with some aspects of reputational and capture theories, as well as with corporate bias theory

International and Temporal Comparative Analysis of UK and US Drug Safety Regulation in Changing Political Contexts

Modern UK drug regulation began in 1971. In view of significant neo-liberal political reforms to drug regulation in the UK and US since the early 1990s, this article compares the performance of UK and US drug safety regulation during both 1971- 1992 and 1993-2004, by investigating drug safety withdrawals (DSWs). Combined quantitative and comprehensive qualitative regulatory case history methodology is employed to explain comparative trends in DSWs and relate them to the key claims of central regulatory theories. It is found that there was a dramatic increase in DSWs in the US during 1993-2004 compared with 1971-1992, and a major increase in the extent to which drugs withdrawn on safety grounds in the UK were left on the US market. Analysis reveals that these findings are best explained by changes in institutional regulatory culture at FDA, consequent upon neo-liberal reforms during 1993-2004, which meant that US regulators adopted more permissive interpretations of safety signals and associated risk-benefit assessments leading to more unsafe drugs being approved on to the US market than during 1971-1992. Changes in the UK are less marked because it already embraced a relatively permissive regulatory culture during 1971-1992 and neo-liberal reforms post-1992 were more attenuated. It is concluded that the changes support corporate bias theory, and that, to improve patient protection, drug safety regulation in the UK and US should shift direction towards the US regulatory model of 1971-92

Exploring RNA interference in the agricultural pests western corn rootworm, fall armyworm, and southern green stink bug

RNA interference (RNAi) is a highly conserved cellular process whereby small regulatory RNAs bound to argonaute proteins produce sequence-specific silencing of longer complementary RNAs. The agricultural biotechnology industry has taken advantage of RNAi to control insect pests through the use of transgenic crops expressing insecticidal RNAs. Upon introduction of double-stranded RNA into a pest, the complementary target messenger RNA is depleted and results in a lethal phenotype. For reasons that are not fully defined, certain insects respond differently to orally introduced RNAs, leaving holes in the manageability of all agricultural pests through this promising new technology. Furthermore, there are indications that insects may be able to develop resistance to crop-mediated RNAi through natural downregulation of RNAi pathway genes, among other proposed mechanisms. Using bioinformatics, next-generation sequencing, and insect bioassays, eight genes essential for RNAi were examined in three important agricultural insect pests for their potential involvement both in the differing responses to exogenous RNAs observed across these insects, and in development of resistance to insecticidal RNAs. These genes include drosha, dicer-1, dicer-2, pasha, loquacious, r2d2, argonaute 1, and argonaute 2. Putative homologues of the well-characterized Drosophila melanogaster genes were identified in the western corn rootworm (Diabrotica virgifera virgifera), fall armyworm (Spodoptera frugiperda), and southern green stink bug (Nezara viridula) and compared using translated gene products. All genes were present in each insect and most showed conservation of basic protein domain structure, but differences in the number of isoforms and expression level of pasha, loquacious, r2d2, argonaute 1, and argonaute 2 were found. Sequencing experiments in each insect revealed the presence of small RNAs typical of the products of RNAi pathways, including conserved microRNAs. Abundance and distribution of these RNAs varied across life stage and insect. Finally, transcript depletion experiments were conducted in rootworm, and adverse phenotypic effects for each gene were observed. Taken together, these results suggest that while differences in these eight genes could contribute to variation in the RNAi pathways of these insects and therefore to variation in response to exogenous RNAs, they are unlikely to promote development of resistance to RNAi-based technology through expression pattern changes

Interactions of a Dopamine D Receptor Agonist with Glutamate NMDA Receptor Antagonists on the Volitional Consumption of Ethanol by the mHEP Rat

Stimulation of the dopamine D1 receptor is reported to cause the phosphorylation of DARPP-32 at the thre34 position and activates the protein. If intracellular Ca2+ is increased, such as after activation of the glutamate NMDA receptor, calcineurin activity increases and the phosphates will be removed. This balance of phosphorylation control suggests that a D1 receptor agonist and a NMDA glutamate receptor antagonist should have additive or synergistic actions to increase activated DARPP-32 and consequent behavioral effects. This hypothesis was tested in a volitional consumption of ethanol model: the selectively bred Myers’ high ethanol preferring (mHEP) rat. A 3-day baseline period was followed by 3-days of twice daily injections of drug(s) or vehicle(s) and then a 3-day post-treatment period. Vehicle, the D1 agonist SKF 38393, the non-competitive NMDA receptor antagonist memantine, or their combination were injected 2 h before and after lights out. The combination of 5.0 mg/kg SKF 38393 with either 3.0 or 10 mg/kg memantine did not produce an additive or synergistic effect. For example, 5.0 mg/kg SKF reduced consumption of ethanol by 27.3% and 10 mg/kg memantine by 39.8%. When combined, consumption declined by 48.2% and the proportion of ethanol solution to total fluids consumed declined by 17%. However, the consumption of food also declined by 36.6%. The latter result indicates that this dose combination had a non-specific effect. The combination of SKF 38393 with (+)-MK-801, another NMDA receptor antagonist, also failed to show an additive effect. The lack of additivity and specificity suggests that the hypothesis may not be correct for this in vivo model. The interaction of these different receptor systems with intraneuronal signaling and behaviors needs to be studied further