Assessing the diversity of New Zealand freshwater harpacticoid copepods (Crustacea: Copepoda) using mitochondrial DNA (COI) barcodes

Taxonomic and ecological studies of freshwater harpacticoid copepods are limited globally by the ability to easily and accurately identify specimens. Here, we test the use of the mitochondrial cytochrome c oxidase subunit I (COI) gene locus as a tool for assessing the diversity of freshwater Harpacticoida. We obtained sequences from New Zealand harpacticoid copepods, representing two families, five genera and nine species, including the non-indigenous Elaphoidella sewelli. All species were delineated by the COI gene. However, high intraspecific diversity was evident among populations of Elaphoidella bidens (>12%), and between North and South Island populations of Bryocamptus pygmaeus (>18%), potentially indicating the presence of morphologically cryptic taxa. We suggest that mitochondrial DNA (COI) sequences can provide a useful tool for the routine identification of freshwater harpacticoid copepods. Applications of these data will include assessing species diversity and biogeography as well as assisting with the detection of non-indigenous species.     

Computational prediction of human metabolic pathways from the complete human genome

Background  

We present a computational pathway analysis of the human genome that assigns enzymes encoded therein to predicted metabolic pathways. Pathway assignments place genes in their larger biological context, and are a necessary first step toward quantitative modeling of metabolism.     

Cost-Effectiveness of Including a Nurse Specialist in the Treatment of Urinary Incontinence in Primary Care in the Netherlands

Objective

Incontinence is an important health problem. Effectively treating incontinence could lead to important health gains in patients and caregivers. Management of incontinence is currently suboptimal, especially in elderly patients. To optimise the provision of incontinence care a global optimum continence service specification (OCSS) was developed. The current study evaluates the costs and effects of implementing this OCSS for community-dwelling patients older than 65 years with four or more chronic diseases in the Netherlands.

Method

A decision analytic model was developed comparing the current care pathway for urinary incontinence in the Netherlands with the pathway as described in the OCSS. The new care strategy was operationalised as the appointment of a continence nurse specialist (NS) located with the general practitioner (GP). This was assumed to increase case detection and to include initial assessment and treatment by the NS. The analysis used a societal perspective, including medical costs, containment products (out-of-pocket and paid by insurer), home care, informal care, and implementation costs.

Results

With the new care strategy a QALY gain of 0.005 per patient is achieved while saving €402 per patient over a 3 year period from a societal perspective. In interpreting these findings it is important to realise that many patients are undetected, even in the new care situation (36%), or receive care for containment only. In both of these groups no health gains were achieved.

Conclusion

Implementing the OCSS in the Netherlands by locating a NS in the GP practice is likely to reduce incontinence, improve quality of life, and reduce costs. Furthermore, the study also highlighted that various areas of the continence care process lack data, which would be valuable to collect through the introduction of the NS in a study setting.     

Ozone effects in a drier climate: implications for stomatal fluxes of reduced stomatal sensitivity to soil drying in a typical grassland species

The widely distributed temperate grassland species Dactylis glomerata was grown in competition with Ranunculus acris at two different watering regimes and exposed for 20 weeks to eight ozone treatments with mean concentrations ranging from 16.2 to 89.5 ppb, representing pre‐industrial to predicted post‐2100 ozone climates. Measurements of stomatal conductance were used to parameterize ozone flux models for D. glomerata. For the first time, a modification was made to the standard flux model to account for the observed decrease in sensitivity of stomatal conductance to reduced water availability with increasing ozone. Comparison of calculated cumulative ozone flux between the two versions of the model demonstrated that exclusion of the ozone effect on stomatal conductance in the standard flux model led to a large underestimation of ozone fluxes at mid‐ to high‐ozone concentrations. For example, at a mean ozone concentration of 55 ppb (as predicted for many temperate areas in the next few decades), the standard flux model underestimated ozone fluxes in D. glomerata by 30–40% under reduced water availability. Although the modified flux model does not markedly change the flux‐based critical level for D. glomerata, this study indicates that use of the standard flux model to quantify the risk of ozone damage to a widely distributed grassland species such as D. glomerata in areas where high ozone concentrations and reduced soil moisture coincide could lead to an underestimation of effects. Thus, this study has shown that under predicted future climate change and ozone scenarios, ozone effects on vegetation may be even greater than previously predicted in the drier areas of the world.     

Thioredoxin-interacting protein deficiency disrupts the fasting-feeding metabolic transition

Through a positional cloning approach, the thioredoxin-interacting protein gene (Txnip) was recently identified as causal for a form of combined hyperlipidemia in mice (Bodnar, J. S., A. Chatterjee, L. W. Castellani, D. A. Ross, J. Ohmen, J. Cavalcoli, C. Wu, K. M. Dains, J. Catanese, M. Chu, S. S. Sheth, K. Charugundla, P. Demant, D. B. West, P. de Jong, and A. J. Lusis. 2002. Positional cloning of the combined hyperlipidemia gene Hyplip1. Nat. Genet. 30: 110-116). We now show that Txnip-deficient mice in the fed state exhibit a metabolic profile similar to fasted mice, including increased levels of plasma ketone bodies and free fatty acids, decreased glucose, and increased hepatic expression of peroxisome proliferator-activated receptor-gamma coactivator-1alpha, phosphoenolpyruvate carboxykinase, glucose-6-phosphatase, and acyl-CoA oxidase. Dramatic differences in the expression of key metabolic enzymes were also observed in other tissues, and the fat-to-muscle ratio of Txnip-deficient mice was increased by approximately 40%. We demonstrate an effect of Txnip on the redox status, as the Txnip-deficient mice in the fed state had a significant increase in the ratio of NADH to NAD(+). Surprisingly, we observed that Txnip-deficient mice and wild-type mice had similar levels of thioredoxin activity, suggesting that the effects of Txnip deficiency may be mediated in part by other interactions. These results indicate a role for Txnip in the metabolic response to feeding and the maintenance of the redox status.     

Phosphatidic acid and phosphatidylserine have distinct structural and functional interactions with the nicotinic acetylcholine receptor

Bilayers containing phosphatidylcholine (PC) and the anionic lipid phosphatidic acid (PA) are particularly effective at stabilizing the nicotinic acetylcholine receptor (nAChR) in a functional conformation that undergoes agonist-induced conformational change. The physical properties of PC membranes containing PA are also substantially altered upon incorporation of the nAChR. To test whether or not the negative charge of PA is responsible for this "bi-directional coupling," the nAChR was reconstituted into membranes composed of PC with varying levels of the net negatively charged lipid phosphatidylserine (PS). In contrast to PA, increasing levels of PS in PC membranes do not stabilize an increasing proportion of nAChRs in a functional resting conformation, nor do they slow nAChR peptide hydrogen exchange kinetics. Incorporation of the nAChR had little effect on the physical properties of the PC/PS membranes, as monitored by the gel-to-liquid crystal phase transition temperatures of the bilayers. These results show that a net negative charge alone is not sufficient to account for the unique interactions that occur between the nAChR and PC/PA membranes. Incorporation of the receptor into PC/PS membranes, however, did lead to an altered head group conformation of PS possibly by recruiting divalent cations to the membrane surface. The results show that the nAChR has complex and unique interactions with both PA and PS. The interactions between the nAChR and PS may be bridged by divalent cations, such as calcium.     

Interspecific competition alters leaf stoichiometry in 20 grassland species

The extensive use of traits in ecological studies over the last few decades to predict community functions has revealed that plant traits are plastic and respond to various environmental factors. These plant traits are assumed to predict how plants compete and capture resources. Variation in stoichiometric ratios both within and across species reflects resource capture dynamics under competition. However, the impact of local plant diversity on species‐specific stoichiometry remains poorly studied. Here, we analyze how spatial and temporal diversity in resource‐acquisition traits affects leaf elemental stoichiometry of plants (i.e. the result of resource capture) and how flexible this stoichiometry is depending on the functional composition of the surrounding community. Therefore, we assessed inter‐ and intraspecific variations of leaf carbon (C), nitrogen (N), and phosphorus (P) (and their ratios) of 20 grassland species in a large trait‐based plant diversity experiment located in Jena (Germany) by measuring leaf elemental concentrations at the species‐level along a gradient in plant trait dissimilarity. Our results show that plants showed large intra‐ and interspecific variation in leaf stoichiometry, which was only partly explained by the functional group identity (grass or herb) of the species. Elemental concentrations (N, P, but not C) decreased with plant species richness, and species tended to become more deviant from their monoculture stoichiometry with increasing trait dissimilarity in the community. These responses differed among species, some consistently increased or decreased in P and N concentrations; for other species, the negative or positive change in P and N concentrations increased with increasing trait difference between the target species and the remaining community. The strength of this relationship was significantly associated to the relative position of the species along trait gradients related to resource acquisition. Trait‐difference and trait‐diversity thus were important predictors of how species’ resource capture changed in competitive neighbourhoods.     

Conformational analysis of macrocyclic frankincense (<Emphasis Type="Italic">Boswellia</Emphasis>) diterpenoids

Frankincense oleoresin has been used in traditional medicine for more than 5000 years. The phytochemistry of frankincense (Boswellia spp.) resins includes triterpenoids (including boswellic acids and their derivatives), diterpenoids (cembrenoids and cneorubenoids), and essential oils. The macrocyclic cembrene diterpenoids may play a part in the biological activities of frankincense resin, but neither the biological targets nor the modes of interaction with the targets are currently known. How these macrocycles interact with biological macromolecules likely depends on what conformation(s) are energetically available to them. In this work, a conformational analysis of 15 Boswellia cembrene diterpenoids and 1 verticillane diterpenoid was carried out at the B3LYP/6-31G* and M06-2X/6-31G* levels of theory, including the SM8 aqueous solvation model. The lowest-energy conformations of boscartin B and incensole oxide were the same as the previously reported X-ray crystal structures, while the lowest-energy conformations of boscartins A and C were very similar to the crystal structures. Boscartins D-H and isoincensole oxide showed only one low-energy conformation for each compound and are predicted to be conformationally locked. Incensole, isoincensolol, and serratol are predicted to be conformationally mobile with several low-energy forms. The conformational mobility of Boswellia cembrenoid diterpenoids depends largely on the degree of epoxidation, either oxirane or tetrahydrofuran rings.