Efficacy of montelukast in the treatment of chronic obstructive pulmonary disease in five horses

Five horses with moderate to severe chronic obstructive pulmonary disease (COPD) were treated with 0.11 (0.01) mg/kg bodyweight of montelukast, a cysteinyl leukotriene receptor antagonist, once a day for 26 days. The horses were evaluated clinically and endoscopically and subjected to arterial blood gas analysis and lung function tests before and after the period of treatment, and the plasma concentrations of montelukast were determined by high-performance liquid chromatography with fluorescence detection. The treatment did not result in statistically significant differences in the total scores of clinical and endoscopical signs, or in the difference in the arterioalveolar partial pressure of oxygen, maximal changes in pleural pressure, pulmonary resistance or dynamic compliance. The mean (sd) peak plasma concentration (C(max0) of montelukast was 12 (4) ng/ml and was reached 66 (13) minutes (t(max)) after its oral administration. The dose of montelukast per kg bodyweight was approximately the same as that for human beings, but the C(max) in the horses was 28 times lower and the t(max) was reached in one-fifth of the time, suggesting that its oral bioavailability may be lower.     

Relationships of feedlot feed efficiency, performance, and feeding behavior with metabolic rate, methane production, and energy partitioning in beef cattle

Residual feed intake (RFI) is the difference between the actual and expected feed intake of an animal based on its BW and growth rate over a specified period. The biological mechanisms underlying the variation in feed efficiency in animals with similar BW and growth rate are not well understood. This study determined the relationship of feedlot feed efficiency, performance, and feeding behavior with digestion and energy partitioning of 27 steers. The steers were selected from a total of 306 animals based on their RFI following feedlot tests at the University of Alberta Kinsella Research Station. Selected steers were ranked into high RFI (RFI > 0.5 SD above the mean, n = 11), medium RFI (RFI +/- 0.5 SD above and below the mean, n = 8), and low RFI (RFI < -0.5 SD below the mean, n = 8). The respective BW +/- SD for the RFI groups were 495.6 +/- 12.7, 529.1 +/- 18.6, and 501.2 +/- 15.5 kg. Digestibility and calorimetry trials were performed on a corn-or barley-based concentrate diet in yr 1 and 2, respectively, at 2.5 x maintenance requirements. Mean DMI (g/kg of BW(0.75)) during the measurements for high-, medium-, and low-RFI groups, respectively, were 82.7 +/- 2.0, 78.8 +/- 2.6, and 81.8 +/- 2.5 and did not differ (P > 0.10). Residual feed intake was correlated with daily methane production and energy lost as methane (r = 0.44; P < 0.05). Methane production was 28 and 24% less in low-RFI animals compared with high- and medium-RFI animals, respectively. Residual feed intake tended to be associated (P < 0.10) with apparent digestibilities of DM (r = -0.33) and CP (r = -0.34). The RFI of steers was correlated with DE (r = -0.41; P < 0.05), ME (r = -0.44; P < 0.05), heat production (HP; r = 0.68; P < 0.001), and retained energy (RE; r = -0.67; P < 0.001; energy values are expressed in kcal/kg of BW(0.75)). Feedlot partial efficiency of growth was correlated (P < 0.01) with methane production (r = -0.55), DE (r = 0.46), ME (r = 0.49), HP (r = -0.50), and RE (r = 0.62). With the exception of HP (r = 0.37; P < 0.05), feed conversion ratio was unrelated to the traits considered in the study. Feeding duration was correlated (P < 0.01) with apparent digestibility of DM (r = -0.55), CP (r = -0.47), methane production (r = 0.51), DE (r = -0.52), ME (r = -0.55), and RE (r = -0.60). These results have practical implications for the selection of animals that eat less at a similar BW and growth rate and for the environmental sustainability of beef production.     

Detection of expressed fungal Type I polyketide synthase genes in a forest soil

Secondary metabolites synthesized via the polyketide pathway are thought to mediate interference competition between soil microorganisms as well as cell-to-cell signaling. Although their synthesis has been documented in laboratory culture, it remains uncertain whether these compounds are actually produced under field conditions. Here, we report the presence and expression of fungal Type I polyketide synthase (PKS) genes in the organic horizon of a forest soil. If these expressed PKS genes produce compounds that elicit antagonistic interactions among soil microorganisms, then it could be a factor structuring microbial communities in soil.     

Soil organic carbon in the rocky desert of northern Negev (Israel)

Purpose

So far, the soil organic carbon (SOC) literature is dominated by studies in the humid environments with huge stocks of vulnerable carbon. Limited attention has been given to dryland ecosystems despite being often considered to be highly sensitive to environmental change. Thus, there is insufficient research about the spatial patterns of SOC stocks and the interaction between soil depth, ecohydrology, geomorphic processes, and SOC stocks. This study aimed at identifying the relationship between surface characteristics, vegetation coverage, SOC, and SOC stocks in the arid northern Negev in Israel.

Materials and methods

The study site Sede Boker is ideally suited because of well-researched but variable ecohydrology. For this purpose, we sampled five slope sections with different ecohydrologic characteristics (e.g., soil and vegetation) and calculate SOC stocks. To identify controlling factors of SOC stocks on rocky desert slopes, we compared soil properties, vegetation coverage, SOC concentration, and stocks between the five ecohydrologic units.

Results and discussion

The results show that in Sede Boker, rocky desert slopes represent a significant SOC pool with a mean SOC stock of 0.58?kg?C?m^?2 averaged over the entire study area. The spatial variability of the soil coverage represents a strong control on SOC stocks, which varies between zero in uncovered areas and 1.54?kg?C?m^?2 on average in the soil-covered areas. Aspect-driven changes of solar radiation and thus of water availability are the dominant control of vegetation coverage and SOC stock in the study area.

Conclusions

The data indicate that dryland soils contain a significant amount of SOC. The SOC varies between the ecohydrologic units, which reflect (1) aspect-driven differences, (2) microscale topography, (3) soil formation, and (4) vegetation coverage, which are of greatest importance for estimating SOC stocks in drylands.     

Diversity of bacterial laccase-like multicopper oxidase genes in forest and grassland Cambisol soil samples

Laccases- or laccase-like multicopper oxidases (LMCO) catalyze the oxidation of various substrates, such as phenols, diamines and metals, coupled with the reduction of molecular oxygen to water. Compared to studies on function and diversity of LMCO in plants and fungi, little is known about this enzyme type in bacteria and especially on their possible implication in degradation of organic matter in soils. This study presents a molecular investigation of the diversity and distribution of bacterial LMCO genes among three upper horizons of a forest Cambisol and in a grassland Cambisol. Some culture strains of soil bacteria were also analyzed at the molecular level and for their capability to oxidize naturally occurring 2,6-dimethoxyphenol, a LMCO substrate. A high LMCO gene diversity was found in the Cambisol soil samples with 16 distinct sequence type clades, of which approximately one half was not matching with any reference sequence of known bacteria. The highest richness of bacterial LMCO genes was observed in the organic horizon of the forest soil, which is concomitant with a previous analysis of the diversity of fungal laccase genes and corresponding soil laccase activity. Some clusters of sequence types showed a specific distribution in one of the soils or in horizons, while others appeared more ubiquist. Multiple bacterial LMCO genes were described in Agromyces salentinus and Sinorhizobium morelense, what so far was only known from fungi.     

Hydrological pathway and source area of nutrient losses identified by a multi-scale monitoring in an agricultural catchment

The objectives of the study were to identify principal hydrological pathways and source areas of N and P losses by multi-scale monitoring and to estimate total nutrient losses from the catchment. An agricultural catchment with rain-fed agriculture and irrigated paddy fields in subtropical China was monitored with regularly sampling, together with intensive sampling during and after rain storms. Regular weekly sampling showed that the N concentrations in the overland flows from the upland and paddy fields were higher than those from the streams, but lower than those in the subsurface waters. The N concentration, on average, was 10.0 mg L^− 1 in the well and 1.7 mg L^− 1 in the spring water, the former was 10.2 times as high as that in the stream waters (1.0–1.5 mg L^− 1). Nitrogen and P in the overland flows originated dominantly in particulate forms from the uplands (over 70%) and in dissolved forms from the paddy fields. Inorganic N and P dominated in the streams and subsurface waters. The intensive sampling allowed us to establish flow-nutrient concentration relationships and to extrapolate nutrient losses during rainstorms without regular sampling. The extrapolation increased the estimated nutrient losses by about 30% to 50%. The average total nutrient losses within three water years were estimated as 21 kg N ha^− 1 yr^− 1 and 1 kg P ha^− 1 yr^− 1, accounting for 9.5% and 1.4% of chemical N and P fertilizers applied to the catchment after subtracting the nutrient inputs with irrigation and rainfall. The estimation showed that paddy fields were as important as the uplands in terms of nutrient losses. These results suggest that control of soil erosion and excessive irrigation could be effective to reduce nutrient export through overland flow and subsurface flow.