Impact of the antibiotic sulfadiazine and pig manure on the microbial community structure in agricultural soils

Large amounts of veterinary antibiotics enter soil via manure of treated animals. The effects on soil microbial community structure are not well investigated. In particular, the impact of antibiotics in the presence of manure is poorly understood. In this study, two agricultural soils, a sandy Cambisol (KS) and a loamy Luvisol (ML), were spiked with manure and sulfadiazine (SDZ; 0, 10 and 100 μg g^?1) and incubated for 1, 4, 32 and 61 days. Untreated controls received only water. The microbial community structure was characterised by investigating phospholipid fatty acids (PLFA) and using PCR–denaturing gradient gel electrophoresis (DGGE) of 16S rDNA. The total concentration of PLFA increased with addition of manure and was reduced by both SDZ concentrations at incubation times >4 days. The SDZ addition decreased the bacteria:fungi ratio. The largest stress level, measured as ratio of PLFA (cyc17:0 + cyc19:0)/(16:1ω7c + 18:1ω7c), was found for the controls, followed by the manure treatments and the SDZ treatments. A discriminant analysis of the PLFA clearly separated treatments and incubation times. Both soils differed in total PLFA concentrations and Gram^?:Gram⁺ ratios, but showed similar changes in PLFA pattern upon soil treatment. Effects of manure and SDZ on the bacterial community structure were also revealed by DGGE analysis. Effects on pseudomonads and β-proteobacteria were less pronounced. While community structure remained altered even after two months, the extractable concentrations of SDZ decreased exponentially and the remaining solution concentrations after 32 days were ≤27% of the spiking concentration. Our results demonstrate that a single addition of SDZ has prolonged effects on the microbial community structure in soils.     

Potential renal acid load in the diet of children and adolescents: impact of food groups, age and time trends

OBJECTIVE: The impact of acid-base balance on health is widely accepted. Here, we describe the potential renal acid load (PRAL) in the diet of healthy German children and adolescents. DESIGN: The Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) Study is an ongoing longitudinal (open cohort) study (start 1985) collecting detailed data on diet, growth, development and metabolism in infants, children and adolescents. SETTING: Research Institute of Child Nutrition, Dortmund. SUBJECTS: Seven hundred and twenty children and adolescents (351 boys and 369 girls), aged 3-18 years, provided 4187 yearly collected 3-day dietary records between 1995 and 2005. RESULTS: Mean daily PRAL was positive in all age/sex groups (6-21 mEq day-1), and significantly higher in boys than in girls after the age of 8 years, even when calculated as mEq MJ-1. Fruits, vegetables and potatoes had a negative impact on PRAL; cheese, dairy products, cereals/bread and meat/fish/eggs had a positive impact. In a mixed linear model, PRAL, expressed as mEq day-1 and mEq MJ-1, remained stable during the study period, since time trends of PRAL-relevant food groups countervail each other. PRAL intake (mEq MJ-1) was significantly positively associated (P < 0.0001) with fat intake (% of energy intake, %E), but negatively with carbohydrate intake (%E; P < 0.0001). CONCLUSIONS: The analysis of dietary habits in our sample of German children and adolescents showed a moderate excess of acidity. Especially older boys should be encouraged to eat more potatoes and vegetables as good sources of dietary alkalinity. The PRAL concept is compatible with current concepts for a healthy diet.     

From genetic diversity and structure to conservation: Genetic signature of recent population declines in three mouse lemur species (Microcebus spp.)

The exceptional biodiversity of Madagascar is threatened by anthropogenic landscape changes that took place during the 2000 years of human colonization. This study focuses on the influence of geographic distance and forest fragmentation on genetic diversity and population differentiation of three rare, nocturnal, arboreal lemur species in northwestern Madagascar. Historic declines in population sizes as a consequence of forest fragmentation are quantified and dated. Eighteen sites were visited, and a total of 205 Microcebus ravelobensis, 45 M. bongolavensis and 78 M. danfossi were genotyped with eight microsatellite loci. Genetic differentiation among the sites, as measured by F_ST, ranged from 0.01 to 0.19. These values were significant in almost all cases and indicated genetic structure in the samples. Isolation-by-distance was detected in one species and a STRUCTURE analysis indicated that fragmentation further promoted genetic differentiation. Bayesian methods revealed that populations from all three species underwent a major demographic collapse of around two orders of magnitude. This decrease probably began after the arrival of humans, most likely within the last 500 years. This result suggests that anthropogenic changes may have been limited during the first 1500 years of human colonization in all three ranges. Two of the study species (M. danfossi, M. bongolavensis) lack effectively protected areas in their ranges. Consequently, quick conservation actions are now needed in order to secure the remaining genetic diversity of these species.     

Termite control with microencapsulated permethrin

Bait methods with microencapsulated active ingredients are proposed for controlling local populations of subterranean termites. The foraging workers will take up the microcapsules, transport them to the nest and pass them to their nestmates. In laboratory tests microencapsulated formulations of permethrin had lethal effects on Heterotermes indicola Wasman and Reticulitermes flavipes (Kollar) depending on the amount of active ingredient applied. The time interval between the application of the capsules and the occurrence of insecticidal effects could be modified by changing the wall thickness of the capsules. Tests revealed that the microcapsules were transmitted from donors to recipients by trophallaxis. Microencapsulated formulations from which the solvent used during the manufacturing process had been removed did not reveal any repellent effects in several tests.     

Detection of <Emphasis Type="Italic">Phytophthora nicotianae</Emphasis> and <Emphasis Type="Italic">P. palmivora</Emphasis> in citrus roots using PCR-RFLP in comparison with other methods

Phytophthora nicotianae and P. palmivora are the most important soil-borne pathogens of citrus in Florida. These two species were detected and identified in singly and doubly infected plants using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of internal transcribed spacer (ITS) regions of ribosomal DNA. The sensitivity of the PCR-RFLP was analyzed and the usefulness of the method evaluated as an alternative or supplement to serological methods and recovery on semi-selective medium. In a semi-nested PCR with universal primers ITS4 and ITS6, the detection limit was 1 fg of fungal DNA, which made it 1000× more sensitive than a single-step PCR with primers ITS4 and DC6. The sensitivity of detection for P. nicotianae was shown to be ten-fold lower than for P. palmivora, limiting its detection with restriction profiles in plants infected by both fungal species. Phytophthora nicotianae was detected with species-specific primers in all samples inoculated with this species despite the absence of species-specific patterns in RFLP. In contrast, the incidence of detection of P. palmivora in the presence of P. nicotianae was considerably lower using plating and morphological detection methods. Due to its high sensitivity, PCR amplification of ribosomal ITS regions is a valuable tool for detecting and identifying Phytophthora spp. in citrus roots, provided a thorough knowledge of reaction conditions for the target species is established prior to the interpretation of data.     

Financial optimisation of target diameter harvest of European beech (Fagus sylvatica) considering the risk of decrease of timber quality due to red heartwood

A mature, average stand of European beech was generated based on characteristic data of trial plots. Some 27 different strategies of target diameter harvest, were simulated for up to 80 years with the help of a distance-dependent single-tree growth simulator. The treatments were differing in the size of the target diameter, the beginning and the end of the harvest. Based on a statistical model, the probability of the occurrence of more than 30% of red heartwood at the front-side diameter was calculated for three sections of each log. Using the predicted probability, the decrease of timber quality due to red heartwood for different treatment strategies was assessed. The harvested volume and the predicted timber quality for different harvesting strategies were used to calculate the net revenue achieved in each simulation period with the help of a calculation program. The net present value for variable interest rates of the different harvesting strategies was calculated, assuming free land rent. Using a linear programming approach, optimal areas for different treatment strategies of a modelled forest of 100 ha were calculated under 4 different scenarios. The results of the optimisation showed how the increasing interest rates replaced higher target diameters out of the optimal solution. In contrast to that the treatments with higher target diameter became more important with increasing restrictions concerning budget or ecological constraints.     

Assessment of Atmospheric Heavy Metals by Moss Monitoring with Isothecium Stoloniferum Brid. in the Fraser Valley, B.C., Canada

The atmospheric heavy metal pollution of the Fraser Valley, B.C., Canada was assessed in 1993 by analyzing 62 samples of the common woodland moss Isothecium stoloniferum for lead, cadmium, nickel, zinc, chromium, and manganese. The latter two metals did not show a distinct regional distribution, but lead, cadmium, nickel, and zinc showed distinct pattern along a west-east gradient. High values were found in the metropolitan Vancouver area, located in the west of the study region. Significantly lower values were recorded for mosses from the eastern more rural areas of the Fraser Valley. Metal pollutants are likely to be contained close to their emission sources by alternating south-east, north-west winds. Highest values overall were found in the North Shore Mountains, adjacent to Vancouver. This was related to higher precipitation and short range pollutant transport from the industrialized, heavily populated areas in the floodplain of the Fraser River.     

Spectrophotometric determination of yellow pigment content and evaluation of carotenoids by high-performance liquid chromatography in durum wheat grain

The so-called "yellow pigment" content of durum wheat has been used for a long time as an indicator of the color quality of durum wheat and pasta products. For decades the chemical nature of these pigments has been assigned to carotenoids, mainly to the xanthophyll lutein and its fatty acid esters. The chemical composition of the yellow pigments of eight German durum wheat cultivars was studied. Grains were milled on a laboratory mill. Pigment extraction of millstream fractions was performed according to the optimized ICC standard method 152 procedure, and the chemical composition of the extract was analyzed by isocratic reversed phase high-performance liquid chromatography. all-trans-Lutein ranged from 1.5 to 4 mg kg(-1), and zeaxanthin was found in traces. No lutein esters and carotenes were detected. Surprisingly, the fraction of carotenoids of the complete yellow pigment content amounted to only 30-50% of the yellow pigment quantities, so there are still compounds in durum wheat not yet identified that contribute considerably to the yellow color of the grain extracts. The isolation and chemical identification of those pigments are under investigation.     

Nutrient dynamics in an Andean forest region: a case study of exotic and native species plantations in southern Ecuador

New Forests - Information about nutrient dynamics is of upmost importance in order to contribute to the restoration of degraded forest environments in the Andes of southern Ecuador. This study aims...     

Ecotoxicological testing of sediments and dredged material: an overlooked opportunity?

Purpose

Basing decisions for the management of contaminated sediments on ecotoxicological data is still often met with skepticism by European stakeholders. These concerns are discussed as they pertain to bioassays to show how ecotoxicological data may provide added value for the sustainable management of sediment in aquatic systems.

Materials and methods

Five “concerns” are selected that are often raised by stakeholders. The ecotoxicological practice is discussed in light of the knowledge gained in recent decades and compared with chemical sediment analysis and chemical data.

Results and discussion

Common assumptions such as a higher uncertainty of biotest results for sediments compared to chemical analyses are not supported by interlaboratory comparisons. Some confusion also arises, because the meaning of biotest data is often misunderstood, questioning their significance in light of a limited number of organisms and altered test conditions in the lab. Because biotest results describe a sediment property, they should not be directly equated with an impact upon the biological community. To identify a hazard, however, the possibility of false-negative results due to the presence of contaminants that are not analyzed but are toxic is lower.

Conclusions

The cost of increased investment in ecotoxicological tests is, in our view, small compared with that of making false-negative assessments of sediment/dredged material that can ultimately have long-term environmental costs. As such, we conclude that ecotoxicological testing is an opportunity for sediment management decision-making that warrants more attention and confidence in Europe.