Natural Variation in Maize Aphid Resistance Is Associated with 2,4-Dihydroxy-7-Methoxy-1,4-Benzoxazin-3-One Glucoside Methyltransferase Activity

Plants differ greatly in their susceptibility to insect herbivory, suggesting both local adaptation and resistance tradeoffs. We used maize (Zea mays) recombinant inbred lines to map a quantitative trait locus (QTL) for the maize leaf aphid (Rhopalosiphum maidis) susceptibility to maize Chromosome 1. Phytochemical analysis revealed that the same locus was also associated with high levels of 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside (HDMBOA-Glc) and low levels of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one glucoside (DIMBOA-Glc). In vitro enzyme assays with candidate genes from the region of the QTL identified three O-methyltransferases (Bx10a-c) that convert DIMBOA-Glc to HDMBOA-Glc. Variation in HDMBOA-Glc production was attributed to a natural CACTA family transposon insertion that inactivates Bx10c in maize lines with low HDMBOA-Glc accumulation. When tested with a population of 26 diverse maize inbred lines, R. maidis produced more progeny on those with high HDMBOA-Glc and low DIMBOA-Glc. Although HDMBOA-Glc was more toxic to R. maidis than DIMBOA-Glc in vitro, BX10c activity and the resulting decline of DIMBOA-Glc upon methylation to HDMBOA-Glc were associated with reduced callose deposition as an aphid defense response in vivo. Thus, a natural transposon insertion appears to mediate an ecologically relevant trade-off between the direct toxicity and defense-inducing properties of maize benzoxazinoids.     

Mediation of Clathrin-Dependent Trafficking during Cytokinesis and Cell Expansion by Arabidopsis STOMATAL CYTOKINESIS DEFECTIVE Proteins

STOMATAL CYTOKINESIS DEFECTIVE1 (SCD1) encodes a putative Rab guanine nucleotide exchange factor that functions in membrane trafficking and is required for cytokinesis and cell expansion in Arabidopsis thaliana. Here, we show that the loss of SCD2 function disrupts cytokinesis and cell expansion and impairs fertility, phenotypes similar to those observed for scd1 mutants. Genetic and biochemical analyses showed that SCD1 function is dependent upon SCD2 and that together these proteins are required for plasma membrane internalization. Further specifying the role of these proteins in membrane trafficking, SCD1 and SCD2 proteins were found to be associated with isolated clathrin-coated vesicles and to colocalize with clathrin light chain at putative sites of endocytosis at the plasma membrane. Together, these data suggest that SCD1 and SCD2 function in clathrin-mediated membrane transport, including plasma membrane endocytosis, required for cytokinesis and cell expansion.     

Sports Participation and Positive Correlates in African American,Latino, and White Girls

The purpose of the study was to examine relations among sports participation and positive correlates across African American, Latino, and White girls. Positive correlate variables were self-perceptions (self-worth, body attractiveness, athletic competence), less depression, and participation in extracurricular activities. The sample comprised 372 girls (mean age = 12.03 years). Data were analyzed using multiple-sample structural equation models, controlling for age and income. Across all ethnic groups, greater sports participation was significantly related to higher self-worth, body attractiveness, and athletic competence, and to more extracurricular activity. Among Latino and White girls only, greater sports participation also was related to less depression. There were significant age and income influences on the positive correlates. Findings confirm the existence of significant relationships between organized sports participation and positive correlates among early adolescent African American, Latino, and White girls. Despite a few ethnic differences in relationships, the current study revealed more similarities than differences.     

Inflammation-induced reactive nitrogen species cause proteasomal degradation of dimeric peroxiredoxin-1 in a mouse macrophage cell line

Peroxiredoxin 1 (PRDX1) is an antioxidant enzyme that, when secreted, can act as a proinflammatory signal. Here we studied the regulation of intracellular PRDX1 by lipopolysaccharide (LPS) and interferon-gamma (IFN-γ) in the RAW 264.7 mouse macrophage cell line. While LPS or IFN-γ alone did not affect PRDX1 protein levels, their combination led to an almost complete loss of the PRDX1 dimer. This was likely mediated by the increased production of nitric oxide (NO) as it was reversed by the NO synthase inhibitor L-N-methylarginine (L-NMMA), while a NO-releasing agent decreased PRDX1 levels. Inhibition of the proteasome with MG132 also prevented the loss of the PRDX1 dimer, suggesting that the decrease is due to a NO-activated proteasomal degradation pathway. By contrast with the decrease in protein levels, LPS increased PRDX1 mRNA and this effect was amplified by IFN-γ. Two other Nrf2 target genes, thioredoxin reductase (TXNRD1) and haem oxygenase (HMOX1), were also induced by LPS but IFN-γ did not increase their expression further. This study shows that inflammation differentially regulates PRDX1 at the levels of protein stability and gene expression, and that NO plays a key role in this mechanism.     

Association of the lipoprotein receptor-related protein 2 gene with gout and non-additive interaction with alcohol consumption

Introduction

The T allele of a single nucleotide polymorphism (SNP: rs2544390) in lipoprotein receptor-related protein 2 (LRP2) is associated with higher serum urate and risk of gout in Japanese individuals. SNP rs2544390 also interacts with alcohol consumption in determining hyperuricemia in this population. We investigated the association of rs2544390 with gout, and interaction with all types of alcohol consumption in European and New Zealand (NZ) Māori and Pacific subjects, and a Māori study cohort from the East Coast region of NZ’s North Island.

Methods

Rs2544390 was genotyped by Taqman®. From NZ a total of 1205 controls and 1431 gout cases clinically ascertained were used. Publicly available genotype and serum urate data were utilized from the Atherosclerosis Risk in Communities (ARIC) study and the Framingham Heart Study (FHS). Alcohol consumption data were obtained by consumption frequency questions in all study cohorts. Multivariate adjusted logistic regression was done using STATA.

Results

The T allele of rs2544390 was associated with increased risk of gout in the combined Māori and Pacific Island cohort (OR = 1.20, P = 0.009), and associated with gout in the European subjects, but with a protective effect (OR = 0.79, P_Unadjusted = 0.02). Alcohol consumption was positively associated with risk of gout in Māori and Pacific subjects (0.2% increased risk/g/week, P = 0.004). There was a non-additive interaction between any alcohol intake and the risk of gout in the combined Māori and Pacific cohorts (P_Interaction = 0.001), where any alcohol intake was associated with a 4.18-fold increased risk in the CC genotype group (P = 6.6x10^-5), compared with a 1.14-fold increased risk in the CT/TT genotype group (P = 0.40). These effects were not observed in European subjects.

Conclusions

Association of the T-allele with gout risk in the Māori and Pacific subjects was consistent with this allele increasing serum urate in Japanese individuals. The non-additive interaction in the Māori and Pacific subjects showed that alcohol consumption over-rides any protective effect conferred by the CC genotype. Further exploration of the mechanism underlying this interaction should generate new understanding of the biological role of alcohol in gout, in addition to strengthening the evidence base for reduction of alcohol consumption in the management of gout.     

Physicomechanical Characterization and Optimization of EDTA–mPEG and Avicel®–EDTA–mPEG In Situ Melt Dispersion Mini-Pellets

The purpose of this study was to develop a physicomechanically customizable oral metal chelatory in situ hot melt dispersion mini-pellet entity which could be utilized within a binary drug delivery system. Avicel^® RC/CL type R-591 was included within the in situ hot melt dispersion mini-pellet formulations to determine the physicomechanical effect this compound would have on the mini-pellet formulations. The physicomechanical properties of the hot melt in situ mini-pellet formulations were mathematically fitting to regression curves. Physicomechanical adjustment of the in situ hot melt dispersion mini-pellet formulations could be mathematically predicted with the derived regression curve equations. The addition of Avicel^® RC/CL type R-591 increased the physicomechanical properties such as matrix hardness and increased total disintegration of the in situ hot melt dispersion mini-pellet formulations. The utilization of a physicomechanically customizable oral metal chelatory in situ hot melt dispersion mini-pellet entity within a binary drug delivery system would to achieve a synergistically enhance the activity of a drug-carrying entity or a permeation enhancing entity within a single drug delivery unit. The experimental results indicated that weights of the pellets that achieved optimal hardness ranged between 35 and 45 mg. The melt–dispersion formulations disintegrated within shorter time periods and maintained higher ethylenediaminetetraacetic acid (EDTA) concentrations whereas melt–dispersion formulations which included Avicel^® had superior physicomechanical properties. Disintegration times ranged between 1,000 s for melt–dispersions containing EDTA and methyloxy polyethylene glycol 2000 (mPEG) only, to >6,000 s for melt–dispersions comprising EDTA, mPEG, and Avicel^®.     

A Review of Polymeric Refabrication Techniques to Modify Polymer Properties for Biomedical and Drug Delivery Applications

Polymers are extensively used in the pharmaceutical and medical field because of their unique and phenomenal properties that they display. They are capable of demonstrating drug delivery properties that are smart and novel, such properties that are not achievable by employing the conventional excipients. Appropriately, polymeric refabrication remains at the forefront of process technology development in an endeavor to produce more useful pharmaceutical and medical products because of the multitudes of smart properties that can be attained through the alteration of polymers. Small alterations to a polymer by either addition, subtraction, self-reaction, or cross reaction with other entities have the capability of generating polymers with properties that are at the level to enable the creation of novel pharmaceutical and medical products. Properties such as stimuli-responsiveness, site targeting, and chronotherapeutics are no longer figures of imaginations but have become a reality through utilizing processes of polymer refabrication. This article has sought to review the different techniques that have been employed in polymeric refabrication to produce superior products in the pharmaceutical and medical disciplines. Techniques such as grafting, blending, interpenetrating polymers networks, and synthesis of polymer complexes will be viewed from a pharmaceutical and medical perspective along with their synthetic process required to attain these products. In addition to this, each process will be evaluated according to its salient features, impeding features, and the role they play in improving current medical devices and procedures.     

1H-Nuclear magnetic resonance pattern recognition studies with N-phenylanthranilic acid in the rat: time- and dose-related metabolic effects

N-Phenylanthranilic acid (NPAA) causes renal papillary necrosis (RPN) in the rat following repeated oral dosing. Non-invasive early detection of RPN is difficult, but a number of potential biomarkers have been investigated, including phospholipid and uronic acid excretion. This study used ¹H-nuclear magnetic resonance (NMR) spectroscopic analysis of urine to investigate urinary metabolic perturbations occurring in the rat following exposure to NPAA. Male Alderley Park rats received NPAA (300, 500 or 700?mg?kg^?1?day^?1 orally) for 7?days, and urine was collected on days 7–8, 14–15, 21–22 and 28–29. In a separate study, urine was collected on days 1–2, 3–4, 5–6 and 7–8 from rats receiving 500?mg?kg^?1?day^?1. Samples were analysed by ¹H NMR spectroscopy combined with multivariate data analysis and clinical chemistry. Histopathology and clinical chemistry analysis of terminal blood samples was carried out following termination on days 4, 6, 8 and 29 (4?week time course) and days 2, 4, 6 and 8 (8?day study). Urine analysis revealed a marked, though variable, excretion of β-hydroxybutyrate, acetoacetate and acetone (ketone bodies) seen on days 3–4, 5–6 and 7–8 of the study. It is postulated that the ketonuria might be secondary to an alteration in fatty acid metabolism due to inhibition of prostaglandin synthesis. In addition, an elevation in urinary ascorbate was observed during the first 8?days of the study. Ascorbate is considered to be a biomarker of hepatic response, probably reflecting an increased hepatic activity due to glucuronidation of NPAA.