Evaluating the risk of tick‐borne relapsing fever among occupational cavers—Austin,TX, 2017

Tick‐borne relapsing fever (TBRF) is a potentially serious spirochetal infection caused by certain species of Borrelia and acquired through the bite of Ornithodoros ticks. In 2017, Austin Public Health, Austin, TX, identified five cases of febrile illness among employees who worked in caves. A cross‐sectional serosurvey and interview were conducted for 44 employees at eight organizations that conduct cave‐related work. Antibodies against TBRF‐causing Borrelia were detected in the serum of five participants, four of whom reported recent illness. Seropositive employees entered significantly more caves (Median 25 [SD: 15] versus Median 4 [SD: 16], p = 0.04) than seronegative employees. Six caves were entered more frequently by seropositive employees posing a potentially high risk. Several of these caves were in public use areas and were opened for tours. Education of area healthcare providers about TBRF and prevention recommendations for cavers and the public are advised.     

Voluntary intake and milk production in F1 Holstein × zebu cows in confinement

The objective of this study was to evaluate the nutrient intake and milk production in Holstein × zebu (F1) cows in feedlot. Eighteen F1 cows were used, divided into three treatments; six were Holstein × Gir (HGI), six were Holstein × Guzerat (HGU), and another six were Holstein × Nelore (HNE), which had recently calved, distributed into simple, random samples, under the same feeding conditions of corn silage and concentrate with 20% crude protein. The three-marker method was used (LIPE, titanium dioxide, and iADF) to estimate the individual intake and digestibility of the nutrients for the cows in group. The mathematical model used to establish the lactation curves was: Y = at(b)e(-ct) by Wood (Nature 216:164-165, 1967). The statistical analyses for the nutrient intake and digestibility, as well as parameters of metabolic efficiency, were performed using multiple linear regression (α = 5%). No effect (P > 0.05) of genetic group was observed for any of the variables studied. The intake and digestibility of the nutrients and the microbial nitrogen presented quadratic curves as a function of the lactation period (P < 0.05). The HGU cows exhibited an accumulated milk production of 4,946.81 kg at 305 days, whereas the HGI cows produced 4,821.78 kg. The HNE cows displayed inferior performance, with a production of 3,674.98 kg. It was concluded that, in confinement, F1 cows from different genetic groups do not exhibit different intake, digestibility, or metabolic efficiency. The HGU and HGI cows have greater cumulative production at 305 days.     

Drivers of bryophyte diversity allow implications for forest management with a focus on climate change

Understanding the major drivers of diversity in forests is crucial for ecologists, conservationists, and particularly forest managers. In most forested habitats, bryophytes are diverse and important primary producers. Here we report the first study of the relative importance of regional macroclimate as compared to local variables on abundance, species richness, and community composition of bryophytes growing in soil and in dead wood in a mountain temperate forest. Using PCA axes, we built predictor sets for macroclimate, microclimate, soil attributes, and dead wood availability. The explanatory power of each set was tested using variance partitioning. Abundance and species richness of soil bryophytes was best explained by microclimate, whereas the community composition did not distinctively differ between the environmental sets. In contrast, dead wood bryophyte abundance, species richness, and community composition was clearly driven by macroclimate. Among the single axes, the component represented best by soil moisture was the main driver for soil bryophyte abundance. In contrast, dead wood bryophyte abundance was mostly affected by components correlated with minimum global radiation and minimum temperatures as well as by the component represented by dead wood. The component represented by canopy openness was superior in explaining the community composition of both soil and dead wood bryophytes. We conclude that (1) dead wood amounts should be increased in closed stands to act as a buffer during climate changes, and (2) open canopy, which provides important habitats for soil-inhabiting bryophytes, should be provided by management with slow reforestation after natural or logging openings.     

Analysis of soil microbial communities based on amplicon sequencing of marker genes

The use of cultivation independent methods has revolutionized soil biology in the last decades. Most popular approaches are based on directly extracted DNA from soil and subsequent analysis of PCR-amplified marker genes by next-generation sequencing. While these high-throughput methods offer novel possibilities over cultivation-based approaches, several key points need to be considered to minimize potential biases during library preparation and downstream bioinformatic analysis. This opinion paper highlights crucial steps that should be considered for accurate analysis and data interpretation.     

Toward metrological traceability for DNA fragment ratios in GM quantification. 2. Systematic study of parameters influencing the quantitative determination of MON 810 corn by real-time PCR

This paper is part of a set of three papers investigating metrological traceability of the quantification of DNA fragments as, for instance, used for quantification of genetic modifications. This paper evaluates the possible impact of several factors on results of real-time Polymerase Chain Reaction (PCR) measurements. It was found that the particle size of the powder samples does not have an influence, whereas the nature of the calibrant (plasmidic or genomic DNA) has a significant effect. Moreover, two real-time PCR detection methods (construct-specific and event-specific) for MON 810 corn were compared. The results obtained in a specifically designed interlaboratory study revealed a significant influence of the DNA extraction method on measurement results when the MON 810 construct-specific real-time PCR detection method was applied. Statistical analyses confirmed the importance of validating DNA extraction methods in conjunction with real-time PCR methods.     

Repeated drying–rewetting cycles and their effects on the emission of CO2, N2O,NO, and CH4 in a forest soil

Prolonged summer droughts due to climate change are expected for this century, but little is known about the effects of drying and wetting on biogenic trace‐gas fluxes of forest soils. Here, the response of CO₂, N₂O, NO, and CH₄ fluxes from temperate forest soils towards drying–wetting events has been investigated, using undisturbed soil columns from a Norway spruce forest in the “Fichtelgebirge”, Germany. Two different types of soil columns have been used for this study to quantify the contribution of organic and mineral horizons to the total fluxes: (1) organic horizons (O) and (2) organic and mineral soil horizons (O+M). Three drying–wetting treatments with different rewetting intensities (8, 20, and 50 mm of irrigation d^–1) have been compared to a constantly moist control to estimate the influence of rainfall intensity under identical drying conditions and constant temperature (+15°C). Drought significantly reduced CO₂, N₂O, and NO fluxes in most cycles. Following rewetting, CO₂ fluxes quickly recovered back to control level in the O columns but remained significantly reduced in the O+M columns with total CO₂ fluxes from the drying–wetting treatment ranging approx. 80% of control fluxes. Fluxes of N₂O and NO remained significantly reduced in both O and O+M columns even after rewetting, with cumulative fluxes from drying–wetting treatments ranging between 20% and 90% of the control fluxes, depending on gas and cycle. Fluxes of CH₄ were small in all treatments and seem to play no significant role in this soil. No evidence for the release of additional gas fluxes due to drying–wetting was found. The intensity of rewetting had no significant effect on the CO₂, N₂O, NO, and CH₄ fluxes, suggesting that the length of the drought period is more important for the emission of these gases. We can therefore not confirm earlier findings that fluxes of CO₂, N₂O, and NO during wetting of dry soil exceed the fluxes of constantly moist soil.     

LC-MS/MS quantification of sulforaphane and indole-3-carbinol metabolites in human plasma and urine after dietary intake of selenium-fortified broccoli

This study aimed at developing a sensitive LC-MS/MS method for the quantification of sulforaphane (SFN) and indole-3-carbinol metabolites in plasma and urine after dietary intake of regular and selenium-fertilized broccoli using stable isotope dilution analysis. In a three-armed, placebo-controlled, randomized human intervention study with 76 healthy volunteers, 200 g of regular (485 μg of total glucosinolates and <0.01 μg of selenium per gram fresh weight) or selenium-fertilized broccoli (589 μg of total glucosinolates and 0.25 μg of selenium per gram fresh weight) was administered daily for 4 weeks. Glucoraphanin and glucobrassicin metabolites quantified in plasma and urine were SFN-glutathione, SFN-cysteine, SFN-cysteinylglycine, SFN-acetylcysteine, and indole-3-carboxaldehyde, indole-3-carboxylic acid, and ascorbigen, respectively. Dietary intake of selenium-fertilized broccoli increased serum selenium concentration analyzed by means of atomic absorption spectroscopy by up to 25% (p < 0.001), but affected neither glucosinolate concentrations in broccoli nor their metabolite concentrations in plasma and urine compared to regular broccoli.     

PCR-based detection of sunflower white blister rust (<Emphasis Type="Italic">Pustula helianthicola</Emphasis> C. Rost &; Thines) in soil samples and asymptomatic host tissue

Sequencing of partial cox2 (part of the mitochondrial cytochrome-c-oxydase (COX) gene) was performed with samples from the oomycete genus Pustula, the white blister rusts of Asteraceae and related families. Sequence comparison uncovered several single nucleotide polymorphisms (SNPs) between P. spinulosa and host specific strains of Pustula isolated from Senecio vulgaris, Tragopogon pratensis and cultivated sunflower, Helianthus annuus. Based on these differences, specific primers were designed for PCR-based detection of white blister rust strains pathogenic to sunflower. The specificity of the primers was confirmed by cross testing with DNA from various oomycetes occurring in the same locality. The limit of detection for DNA of P. helianthicola was 10 pg. This allowed detection with DNA from single sporangia and single oospores. The PCR-based experiments allowed detection of the presence of sunflower white blister rust in soil samples from fields on which infected plants had been cultivated several months before. Moreover, the molecular tools were successfully applied to trace the pathogen in asymptomatic tissue of infected plants, demonstrating the systemic nature of Pustula on sunflower.