Identification and functional analysis of genetic variants of the human beta-glucuronidase in a German population sample

The deleterious consequences of total beta-glucuronidase deficiency, leading to symptomatic mucopolysaccharidosis type VII (MPS VII), have been firmly established. However, the question of whether sequence variations in beta-glucuronidase of non-MPS VII patients affect expression of the enzyme, thereby explaining the wide inter-individual expression, has not been addressed in a systematic manner. In the present study, a population of 965 subjects were screened for enzyme activity and relevant fractions of the beta-glucuronidase gene were sequenced in those individuals belonging to the highest or lowest decile of activity. The study showed a substantial inter-individual variability of beta-glucuronidase in plasma (range 0.5-150.2 micromol/min) and confirmed the association of beta-glucuronidase activity with gender (P < 0.001), age (r = 0.218; P < 0.001) and body mass index (r = 0.311; P < 0.001). We were able to identify six beta-glucuronidase single base substitutions (-1026A > G, -72G > T, -12G > A, +7728C > T, +14 209C > T and +14 604A > G) in 193 non-MPS VII patients at a rate of one single nucleotide polymorphism (SNP) per 520 bp sequenced. The GG genotype of +14 604A > G and the CT genotype of +14 209C > T were associated with higher beta-glucuronidase activity (P < 0.05). Subsequently, reporter gene assays were carried out to elucidate the effects of the SNPs -1026A > G, -72G > T and -12G > A, and the combined genotype -1026A > G and -12G > A observed in one of the subjects. Variant -12G > A reduced the promoter activity (75%; 95% confidence interval 70-84%, P < 0.05). The present study demonstrates that three of the described SNPs influence the activity and/or expression of beta-glucuronidase. Taken together, the data indicate a rather limited influence of genetic factors on inter-individual variability in beta-glucuronidase activity.     

Pharmacokinetics and pharmacodynamics of rosiglitazone in relation to CYP2C8 genotype

OBJECTIVES: Rosiglitazone is metabolically inactivated predominantly via the cytochrome P450 (CYP) enzyme CYP2C8. The functional impact of the CYP2C8*3 allele coding for the Arg139Lys and Lys399Arg amino acid substitutions is controversial. The purpose of this was to clarify the role of this polymorphism with regard to the pharmacokinetics and clinical effects of rosiglitazone. METHODS: From a large sample of healthy volunteers, 14 carriers of the CYP2C8*1/*1 allele, 13 carriers of the *1/*3 allele, and 4 carriers the *3/*3 allele were selected for a clinical study. Rosiglitazone (8 mg) single-dose and multiple-dose pharmacokinetics and its effects on glucose level and body weight were monitored. Plasma and urine concentrations of rosiglitazone and desmethylrosiglitazone were measured, and kinetics was analyzed by noncompartmental and population-kinetic compartmental methods. RESULTS: Mean total clearance values were 0.033 L x h(-1) x kg(-1) (95% confidence interval [CI], 0.030-0.037 L x h(-1) x kg(-1)), 0.038 L x h(-1) x kg(-1) (95% CI, 0.033-0.044 L x h(-1) x kg(-1)), and 0.046 L x h(-1) x kg(-1) (95% CI, 0.033-0.058 L x h(-1) x kg(-1)) in carriers of CYP2C8 genotypes *1/*1, *1/*3, and *3/*3, respectively, on day 1 (P = .02, ANOVA [F test]). Rosiglitazone kinetics could be adequately described by a 1-compartmental model with first-order absorption. Besides CYP2C8 genotype, body weight was a significant covariate (P < .001, log-likelihood ratio test). Elimination half-lives were 4.3, 3.5, and 2.9 hours in CYP2C8*1/*1, *1/*3, and *3/*3 carriers, respectively. Clearance of desmethylrosiglitazone was also higher in CYP2C8*3 allele carriers, with mean values of 1.96 L/h (95% CI, 1.42-2.69 L/h), 2.22 L/h (95% CI, 1.61-3.04 L/h), and 2.47 L/h (95% CI, 1.80-3.39 L/h), respectively (P = .03). The plasma glucose area under the concentration curve was significantly lower after 14 days of taking rosiglitazone compared with day 1 (P = .01, paired t test), but no relationship of the glucose-lowering effect of rosiglitazone with CYP2C8 genotype was observed. CONCLUSIONS: This study showed that the CYP2C8*3 allele confers higher in vivo metabolic capacity than the wild-type CYP2C8*1 allele but the pharmacokinetic differences resulting from CYP2C8*3 were quantitatively moderate.     

Disturbed carnitine regulation in chronic heart failure — Increased plasma levels of palmitoyl-carnitine are associated with poor prognosis

Background/objectives

Heart failure is characterized by disturbed energy metabolism and impaired mitochondrial function. L-carnitine plays a critical role in fatty acid transport into the mitochondria and may thus influence inflammation and myocardial function. The aim of this study was to investigate carnitine metabolism in relation to progression of heart failure (HF).

Methods and results

We examined plasma levels of free L-carnitine as well as several of its precursors and derivates in HF patients (n = 183) and matched healthy controls (n = 111) as well as their relationship with cardiac dysfunction as assessed by echocardiographic measurements, inflammation (CRP) and neurohormonal activation (NT-proBNP) in addition to the prognostic value of carnitine derivates in relation to mortality in these patients. High levels of the carnitine derivates acetyl-carnitine and in particular palmitoyl-carnitine were associated with the degree of HF as evaluated by clinical (NYHA functional class) and neurohormonal assessments. Moreover, plasma levels of palmitoyl-carnitine were associated with serious adverse events (i.e., all-cause mortality and heart transplantation) during follow-up, independently of more established risk markers such as CRP and NT-proBNP, when analyzed by cox-regression and continous net reclassification improvement, but not c-statistics.

Conclusions

Our findings support a role for disturbed carnitine metabolism in the pathogenesis of HF, and suggest that some of its derivates could give prognostic information in these patients.     

Combining high biodiversity with high yields in tropical agroforests

Local and landscape-scale agricultural intensification is a major driver of global biodiversity loss. Controversially discussed solutions include wildlife-friendly farming or combining high-intensity farming with land-sparing for nature. Here, we integrate biodiversity and crop productivity data for smallholder cacao in Indonesia to exemplify for tropical agroforests that there is little relationship between yield and biodiversity under current management, opening substantial opportunities for wildlife-friendly management. Species richness of trees, fungi, invertebrates, and vertebrates did not decrease with yield. Moderate shade, adequate labor, and input level can be combined with a complex habitat structure to provide high biodiversity as well as high yields. Although livelihood impacts are held up as a major obstacle for wildlife-friendly farming in the tropics, our results suggest that in some situations, agroforests can be designed to optimize both biodiversity and crop production benefits without adding pressure to convert natural habitat to farmland.     

A multitaxa assessment of the effectiveness of agri-environmental schemes for biodiversity management

Agri-environmental schemes (AES) aim to restore biodiversity and biodiversity-mediated ecosystem services in landscapes impoverished by modern agriculture. However, a systematic, empirical evaluation of different AES types across multiple taxa and functional groups is missing. Within one orthogonal design, we studied sown flowering AES types with different temporal continuity, size, and landscape context and used calcareous grasslands as seminatural reference habitat. We measured species richness of 12 taxonomic groups (vascular plants, cicadas, orthopterans, bees, butterflies, moths, hoverflies, flower visiting beetles, parasitoid wasps, carabid beetles, staphylinid beetles, and birds) representing 5 trophic levels. A total of 54,955 specimens were identified using traditional taxonomic methods, and bulk arthropod samples were identified through DNA metabarcoding, resulting in a total of 1,077 and 2,110 taxa, respectively. Species richness of most taxonomic groups, as well as multidiversity and richness of pollinators, increased with temporal continuity of AES types. Some groups responded to size and landscape context, but multidiversity and richness of pollinators and natural enemies were not affected. AES flowering fields supported different species assemblages than calcareous grasslands, but assemblages became more similar to those in seminatural grasslands with increasing temporal continuity. Our results indicate that AES flowering fields and seminatural grasslands function synergistically. Flowering fields support biodiversity even when they are relatively small and in landscapes with few remaining seminatural habitats. We therefore recommend a network of smaller, temporally continuous AES flowering fields of different ages, combined with permanent seminatural grasslands, to maximize benefits for biodiversity conservation and ecosystem service delivery in agricultural landscapes.

Human societies are facing a worldwide loss of biodiversity with alarming declines of insect diversity in temperate agricultural landscapes (1, 2). This loss of biodiversity is jeopardizing agricultural production as important ecosystem services ensuring crop yields are directly driven by biodiversity (3). Biodiversity, however, requires suitable habitats for species to persist, forage, nest, reproduce, and hibernate (4, 5). This challenge has been recognized and agri-environmental schemes (AES) have been introduced in the European Union and other regions to reverse biodiversity declines, to restore functional diversity, and to harness the benefits of ecosystem services, like pollination and pest control, in agricultural landscapes (6–8).An important component of AES to fulfill these goals is the establishing of habitats that provide limiting resources, such as food and shelter for a broad range of organisms. Typically, farmers are financially compensated on a per area basis, but the effectiveness of schemes is often unclear. Thus, compensations might not direct farmers’ decisions among different AES to the ecologically most meaningful ones (7). A variety of different habitats are created as AES, ranging from hedgerows to sown flower strips or flowering fields, with the latter being widely used due to their flexible applicability and public appreciation (4). Recent assessments, however, found that overall, European AES are not fulfilling their goals (6, 9). Particularly, the value of AES for securing biodiversity is under debate (10, 11). Beneficial effects previously reported focused on single taxonomic or trophic levels or ecosystem services and varied among study designs, taxa, or services assessed (12–14). Conclusive multitaxa approaches assessing potential services and disservices in one design are missing (8). Furthermore, it is unclear how different properties of AES habitats (e.g., their temporal continuity or size) and varying landscape context affect biodiversity across multiple taxonomic groups.Temporal continuity is an important factor affecting biodiversity. Higher temporal continuity increases heterogeneity within a habitat and creates niches for more species (15, 16). Temporal continuity also enables weak dispersers and higher tropic levels to colonize a habitat, with the latter being dependent on established populations of lower trophic levels (15). In AES habitats, the influence and the effects of temporal continuity have so far been neglected. Newly established flowering fields were found to be more attractive to pollinators than older flowering fields, but pollination services in adjacent fields peak 2 y after initial sowing (14, 17). Older AES habitats could potentially also benefit rare and endangered species with specific habitat requirements, if species assemblages in AES habitats change toward those in permanent species-rich seminatural grasslands with time or increased temporal continuity (18).Apart from temporal continuity, size might be an important predictor for the conservation value of AES habitats. Increasing habitat size leads to an increased species richness as it is accompanied with the establishment of larger, more stable populations and allows higher trophic levels to persist (19–21). It is unclear whether biodiversity in a landscape benefits more from few large habitats or a network of many small habitats (22, 23). Relationships between size and species richness might therefore be essential for the planning and strategic placement of AES habitats.Source habitats for biodiversity are needed in agricultural landscapes to build up local populations in newly established AES habitats from regional species pools (24). Seminatural habitats embedded in agricultural landscapes have been shown to support farmland diversity (25, 26), and thus AES habitats in complex landscapes with high proportions of seminatural habitats potentially host the highest diversity.Here, we investigate the effects of AES differing in temporal continuity, size, and surrounding landscape context over several years on multiple taxonomic groups within one study design. Different types of flowering fields are commonly established by farmers as part of AES to provide additional flower resources. These fields are sown with seed mixtures adapted to local soil properties and taken from regional species pools. After a certain timespan, often varying from 1 to 10 y, flowering fields are returned to crop production. The studied flowering fields differed in temporal continuity from: 1) Newly sown on arable land, over 2) refreshed (i.e., flower fields resown after 5 y) to 3) continuous, 6-y-old flowering fields. Species-rich calcareous grasslands were used as permanent control (Fig. 1 and Table 1). Calcareous grasslands are seminatural biodiversity hotspots in Europe and are preserved by low intensive mowing or grazing (27). We investigated species richness in these 4 AES types across 12 taxonomic groups belonging to 5 trophic levels, including pollinators (bees, butterflies, moths, flower visiting beetles, and hoverflies) and natural enemies (parasitoid wasps, carabid beetles, staphylinid beetles, and birds) as providers of important ecosystem services (3). Species were identified by classic taxonomic techniques (vascular plants, orthopterans, bees, butterflies, moths, flower visiting beetles, carabid beetles, staphylinid beetles, and birds) and DNA metabarcoding (cicadas, hoverflies, and parasitoid wasps). Repeated recordings of a subset of four taxonomic groups (plants, orthopterans, bees, and carabid beetles) within 2 y were performed to clarify whether short-term succession changed assemblages in newly established flowering fields toward those in seminatural calcareous grasslands. Apart from analyses for each taxonomic group, we performed a multidiversity analysis by calculating a diversity index across all taxa, pollinators, and natural enemies (28). Our study aims to judge which types of AES fulfill the goal of restoring biodiversity and ecosystem services in agricultural landscapes best, and should therefore be fostered. Such data are urgently needed to build the scientific basis for a successful transition of European Union and global policies to biodiversity-friendly and sustainable crop production.Open in a separate windowFig. 1.Study design on the landscape and site level. Biodiversity across 12 different taxonomic levels (from top to bottom: Vascular plants, orthopterans, cicadas, bees, butterflies, moths, flower visiting beetles, hoverflies, parasitoid wasps, carabid beetles, staphylinid beetles, birds) was recorded using a variety of classic methods (pan traps, pitfall traps, transect walks, light traps combined with taxonomic identification) as well as metabarcoding analyses (using samples collected with Malaise traps). The different types of flowering fields and calcareous grasslands were located along a gradient of temporal continuity (Table 1). All AES types covered independent gradients of seminatural habitat in the surrounding landscape and habitat size (purple, AES; yellow, arable land; light green, seminatural habitat; dark green, forest; gray, urban). Repeated recordings over 2 y were performed for vascular plants, orthopterans, bees, and carabid beetles to assess whether succession shifted assemblages in flowering fields toward those in seminatural calcareous grasslands.Table 1.Differences in temporal continuity