Membrane Proteins in Action Monitored by pH-Responsive Liquid Crystal Biosensors.

Liquid crystal (LC) biosensors have received significant attention for their potential applications for point-of-care devices due to their sensitivity, low cost, and easy read-out. They have been employed to detect a wide range of important biological molecules. However, detecting the function of membrane proteins has been extremely challenging due to the difficulty of integrating membrane proteins, lipid membranes, and LCs into one system. In this study, we addressed this challenge by monitoring the proton-pumping function of bacteriorhodopsin (bR) using a pH-sensitive LC thin film biosensor. To achieve this, we deposited purple membranes (PMs) containing a 2D crystal form of bRs onto an LC-aqueous interface. Under light, the PM patches changed the local pH at the LC-aqueous interface, causing a color change in the LC thin film that is observable through a polarizing microscope with crossed polarizers. These findings open up new opportunities to study the biofunctions of membrane proteins and their induced local environmental changes in a solution using LC biosensors.

Water Deficit-Induced Changes in Phenolic Acid Content in Maize Leaves Is Associated with Altered Expression of Cinnamate 4-Hydroxylase and p-Coumaric Acid 3-Hydroxylase.

The amino acid phenylalanine is a precursor to phenolic acids that constitute the lignin biosynthetic pathway. Although there is evidence of a role of some phenolic acids in plant responses to pathogens and salinity, characterization of the involvement of phenolic acids in plant responses to drought is limited. Drought reduces water content in plant tissue and can lead to decreased cell viability and increased cell death. We thus subjected maize seedlings to water deficit and evaluated relative water content and cell viability together with p-coumaric acid, caffeic acid and ferulic acid contents in the leaves. Furthermore, we measured the enzymatic activity of cinnamate 4-hydroxylase (EC 1.14.13.11) and p-coumarate 3-hydroxylase (EC 1.14.17.2) and associated these with the expression of genes encoding cinnamate 4-hydroxylase and p-coumarate-3 hydroxylase in response to water deficit. Water deficit reduced relative water content and cell viability in maize leaves. This corresponded with decreased p-coumaric acid but increased caffeic and ferulic acid content in the leaves. Changes in the phenolic acid content of the maize leaves were associated with increased enzymatic activities of cinnamate 4-hydroxylase and p-coumarate hydroxylase. The increased enzymatic activity of p-coumarate 3-hydroxylase was associated with increased expression of a gene encoding p-coumarate 3-hydroxylase. We thus conclude that metabolic pathways involving phenolic acids may contribute to the regulation of drought responses in maize, and we propose that further work to elucidate this regulation may contribute to the development of new maize varieties with improved drought tolerance. This can be achieved by marker-assisted selection to select maize lines with high levels of expression of genes encoding cinnamate 4-hydroxylase and/or p-coumarate 3-hydroxylase for use in breeding programs aimed and improving drought tolerance, or by overexpression of these genes via genetic engineering to confer drought tolerance.

Perceived Versus Demonstrated Understanding of the Complex Medications of Medically Complex Children.

OBJECTIVES: Parents and caregivers of children with medical complexity (CMC) manage complex medication regimens (CMRs) at home. Parental understanding of CMRs is critical to safe medication administration. Regarding CMR administration, we 1) described the population of CMC receiving CMRs; 2) assessed parental perceived confidence and understanding; and 3) evaluated parental demonstrated understanding. METHODS: Cross-sectional clinic-based assessment of knowledge and understanding of CMC using CMRs who received primary care in a large pediatric complex care clinic. CMRs were identified by the receipt of ≥1 of the following: 1) ≥10 concurrent medications; 2) ≥1 high-risk medication; or 3) ≥1 extemporaneously compounded medication. Parents reported their perceived confidence and understanding of CMRs, and then demonstrated understanding through 3 medication-related tasks. RESULTS: Of 156 CMCs, most were <10 years of age (63.5%), white (75%), had neurologic impairment (76.9%), and used a median of 8 medications (IQR, 5-10). Parents were female (76.9%) with a mean age of 38.8 ± 11.5 years, white (69.9%), spoke English (94.2%), and had some college education (82.1%). On 11 confidence and understanding statements, most parents reported a high perceived level of understanding and confidence, with combined agreement or strong agreement ranging between 81.2% and 98.7%. Only 73.1% correctly identified medications taken for specified conditions, 40.4% reported complete dosing parameters, and 54.8% correctly measured 2 different medication doses. Significant differences existed between parental perceived understanding versus the 3 demonstrated tasks (all p < 0.05). CONCLUSIONS: Substantial opportunities exist to improve medication safety and efficacy in the outpatient, in-home setting including improved medication-specific education and medication-related supports.

Inhibition of NOS- like activity in maize alters the expression of genes involved in H2O2 scavenging and glycine betaine biosynthesis.

Nitric oxide synthase-like activity contributes to the production of nitric oxide in plants, which controls plant responses to stress. This study investigates if changes in ascorbate peroxidase enzymatic activity and glycine betaine content in response to inhibition of nitric oxide synthase-like activity are associated with transcriptional regulation by analyzing transcript levels of genes (betaine aldehyde dehydrogenase) involved in glycine betaine biosynthesis and those encoding antioxidant enzymes (ascorbate peroxidase and catalase) in leaves of maize seedlings treated with an inhibitor of nitric oxide synthase-like activity. In seedlings treated with a nitric oxide synthase inhibitor, transcript levels of betaine aldehyde dehydrogenase were decreased. In plants treated with the nitric oxide synthase inhibitor, the transcript levels of ascorbate peroxidase-encoding genes were down-regulated. We thus conclude that inhibition of nitric oxide synthase-like activity suppresses the expression of ascorbate peroxidase and betaine aldehyde dehydrogenase genes in maize leaves. Furthermore, catalase activity was suppressed in leaves of plants treated with nitric oxide synthase inhibitor; and this corresponded with the suppression of the expression of catalase genes. We further conclude that inhibition of nitric oxide synthase-like activity, which suppresses ascorbate peroxidase and catalase enzymatic activities, results in increased H2O2 content.

Drought and exogenous abscisic acid alter hydrogen peroxide accumulation and differentially regulate the expression of two maize RD22-like genes.

Increased biosynthesis of abscisic acid (ABA) occurs in plants in response to water deficit, which is mediated by changes in the levels of reactive oxygen species such as H2O2. Water deficit and ABA induce expression of some RD22-like proteins. This study aimed to evaluate the effect of water deficit and exogenous ABA (50 µM ABA applied every 24 hours for a total of 72 hours) on H2O2 content in Zea mays (maize) and to characterise genes encoding two putative maize RD22-like proteins (designated ZmRD22A and ZmRD22B). The expression profiles of the two putative maize RD22-like genes in response to water deficit and treatment with ABA were examined in leaves. In silico analyses showed that the maize RD22-like proteins share domain organisation with previously characterized RD22-like proteins. Both water deficit and exogenous ABA resulted in increased H2O2 content in leaves but the increase was more pronounced in response to water deficit than to exogenous ABA. Lignin content was not affected by exogenous ABA, whereas it was decreased by water deficit. Expression of both RD22-like genes was up-regulated by drought but the ZmRD22A gene was not influenced by exogenous ABA, whereas ZmRD22B was highly responsive to exogenous ABA.

Ecosystem engineering by a gall-forming wasp indirectly suppresses diversity and density of herbivores on oak trees.

Ecosystem engineers, organisms that modify the physical environment, are generally thought to increase diversity by facilitating species that benefit from engineered habitats. Recent theoretical work, however, suggests that ecosystem engineering could initiate cascades of trophic interactions that shape community structure in unexpected ways, potentially having negative indirect effects on abundance and diversity in components of the community that do not directly interact with the habitat modifications. We tested the indirect effects of a gall-forming wasp on arthropod communities in surrounding unmodified foliage. We experimentally removed all senesced galls from entire trees during winter and sampled the arthropod community on foliage after budburst. Gall removal resulted in 59% greater herbivore density, 26% greater herbivore richness, and 27% greater arthropod density five weeks after budburst. Gall removal also reduced the differences in community composition among trees (i.e., reduced beta diversity), even when accounting for differences in richness. The community inside galls during winter and through the growing season was dominated by jumping spiders (Salticidae; 0.87 ± 0.12 spiders per gall). We suggest that senesced galls provided habitat for spiders, which suppressed herbivorous arthropods and increased beta diversity by facilitating assembly of unusual arthropod communities. Our results demonstrate that the effects of habitat modification by ecosystem engineers can extend beyond merely providing habitat for specialists; the effects can propagate far enough to influence the structure of communities that do not directly interact with habitat modifications.