Utility of Bioluminescent Homogeneous Nucleotide Detection Assays in Measuring Activities of Nucleotide-Sugar Dependent Glycosyltransferases and Studying Their Inhibitors

Traditional glycosyltransferase (GT) activity assays are not easily configured for rapid detection nor for high throughput screening because they rely on radioactive product isolation, the use of heterogeneous immunoassays or mass spectrometry. In a typical glycosyltransferase biochemical reaction, two products are generated, a glycosylated product and a nucleotide released from the sugar donor substrate. Therefore, an assay that detects the nucleotide could be universal to monitor the activity of diverse glycosyltransferases in vitro. Here we describe three homogeneous and bioluminescent glycosyltransferase activity assays based on UDP, GDP, CMP, and UMP detection. Each of these assays are performed in a one-step detection that relies on converting the nucleotide product to ATP, then to bioluminescence using firefly luciferase. These assays are highly sensitive, robust and resistant to chemical interference. Various applications of these assays are presented, including studies on the specificity of sugar transfer by diverse GTs and the characterization of acceptor substrate-dependent and independent nucleotide-sugar hydrolysis. Furthermore, their utility in screening for specific GT inhibitors and the study of their mode of action are described. We believe that the broad utility of these nucleotide assays will enable the investigation of a large number of GTs and may have a significant impact on diverse areas of Glycobiology research.

Carcass Scavenging Relaxes Chemical-Driven Female Interference Competition

ABSTRACTFemale-female nonsexual interference competition is rapidly emerging as a major fitness determinant of biased sex-ratio groups with high female density. How do females overcome such competition? We used adult flour beetle Tribolium castaneum to answer this question, where females from female-biased groups suppressed each other’s fecundity by secreting toxic quinones from their stink glands, revealing a chemical-driven interference competition. The added natal resource did not alleviate these fitness costs. Females also did not disperse more at high female-density. Hence, the competition was neither limited by the total resource availability nor the inability to avoid chemical interference. Instead, protein sequestered via scavenging of nutrient-rich carcasses relaxed the female competition, by increasing their fecundity and reducing the quinone content. Even infected carcasses were scavenged to extract fitness benefits, despite the infection-risk. Finally, individual stink gland components triggered carcass-scavenging to increase fecundity, indicating a potentially novel chemical feedback loop to reduce the competition.

New Approaches to Simulation of Enzymatic Reactions: Mimetic Catalysis

The examples given below, for instance, methane oxidation to methanol and propylene oxidation to propylene oxide, demonstrate experimental approaches to the study of interfering reaction dynamics and, with the help of the determinant equation, the potential abilities of reaction media are assessed and the type of chemical interference determined.

Lack of Behavioral and Chemical Interference Competition for Refuges among Native Treefrogs and Invasive Cuban Treefrogs (Osteopilus septentrionalis)

The introduction of a novel competitor can dramatically alter community dynamics, and competition-mediated impacts often result from biological invasions. Interference competition can be especially problematic as a source of methodological bias for studies seeking to evaluate population and community-level impacts of invasive species. We used polyvinyl chloride (PVC) refugia to conduct laboratory trials to determine whether behavioral or chemical cues of invasive Cuban treefrogs (Osteopilusseptentrionalis) interfere with artificial refuge use by conspecifics or treefrogs native to Florida (USA). We found no evidence of behavioral or chemical competition for refuges by Cuban treefrogs or native treefrogs. The inability of native treefrogs to avoid chemical cues from Cuban treefrogs, despite living sympatrically with the invasive treefrogs for 10–20 years, has important implications for predation risk.

Colour as a backup for scent in the presence of olfactory noise: testing the efficacy backup hypothesis using bumblebees ( Bombus terrestris )

The majority of floral displays simultaneously broadcast signals from multiple sensory modalities, but these multimodal displays come at both a metabolic cost and an increased conspicuousness to floral antagonists. Why then do plants invest in these costly multimodal displays? The efficacy backup hypothesis suggests that individual signal components act as a backup for others in the presence of environmental variability. Here, we test the efficacy backup hypothesis by investigating the ability of bumblebees to differentiate between sets of artificial flowers in the presence of either chemical interference or high wind speeds, both of which have the potential to impede the transmission of olfactory signals. We found that both chemical interference and high wind speeds negatively affected forager learning times, but these effects were mitigated in the presence of a visual signal component. Our results suggest that visual signals can act as a backup for olfactory signals in the presence of chemical interference and high wind speeds, and support the efficacy backup hypothesis as an explanation for the evolution of multimodal floral displays.

Organic acids to eliminate interference by phosphorus in the analysis of silicon by molecular absorption

One of the problems for quantifying the amount of silicon available by molecular absorption is the elimination of chemical interference caused by available phosphorus. The aim of this work was to evaluate different organic acids in eliminating the interference caused by phosphorus in the quantification of available silicon by molecular absorption. The experiments were conducted in the Soil laboratory of the College of Agricultural Sciences at the Universidad de Córdoba, Colombia. For this work, different acids such as tartaric, citric, oxalic and malic were evaluated at two concentrations (0.8 and 1.33 mol L-1). Solutions containing silicon (1 mg L-1) and six concentrations of phosphorus were prepared (0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 mg L-1). The quantification of silicon was conducted by molecular absorption spectrophotometry using a Perkin Elmer Lambda XLS + at 660 nm. The results were subjected to the LSD tests and contrasts using the R software (Development Core Team, version 3.2.2).The results indicated that the oxalic, citric and malic acids at both concentrations produced lower overestimation of silicon in the presence of the P concentrations 0.6, 0.8 and 1.0 mgL-1 than the tartaric acid, which is commonly used as a reference to remove the P interference.