Aerosol indirect effect on biogeochemical cycles and climate

The net effect of anthropogenic aerosols on climate is usually considered the sum of the direct radiative effect of anthropogenic aerosols, plus the indirect effect of these aerosols through aerosol-cloud interactions. However, an additional impact of aerosols on a longer time scale is their indirect effect on climate through biogeochemical feedbacks, largely due to changes in the atmospheric concentration of CO(2). Aerosols can affect land and ocean biogeochemical cycles by physical forcing or by adding nutrients and pollutants to ecosystems. The net biogeochemical effect of aerosols is estimated to be equivalent to a radiative forcing of -0.5 ± 0.4 watts per square meter, which suggests that reaching lower carbon targets will be even costlier than previously estimated.     

Seed and seedling characteristics of hybrid chestnuts (Castanea spp.) derived from a backcross blight-resistance breeding program

New Forests - American chestnut (Castanea dentata) was a foundation species in the eastern United States until chestnut blight (Cryphonectria parasitica) infestation resulted in range-wide...     

Severe Leukemoid Response Associated With Mycobacterium genavense Infection in a Pet Budgerigar (Melopsittacus undulatus)

A 2-year-old pet budgerigar was presented after a period of general malaise that was unresponsive to supportive therapy. Radiographic images revealed a marked hepatomegaly. Hematology results indicated the bird had a severe leukocytosis with marked discrepancy between the hemocytometer white blood cell (WBC) count and WBC estimated from the smear. The leukocytosis was characterized by an extreme heterophilia with marked left shift, including the presence of metamyelocytes and promyelocytes with marked toxic changes, and a marked monocytosis, consistent with a leukemoid response. The bird died despite supportive treatment. Hepatosplenomegaly was present at necropsy. Histopathology of multiple tissues demonstrated acid-fast organisms on Ziehl-Neelsen staining, subsequently identified as Mycobacterium genavese by polymerase chain reaction analysis. Mycobacteriosis should be considered as a differential diagnosis in the presence of a severe leukemoid response with multiple heterophilic precursors in avian species.     

Variations in equid SLC11A1 (NRAMP1) genes and associations with Rhodococcus equi pneumonia in horses

Rhodococcus equi is an important intracellular pathogen of horses, most commonly causing chronic, suppurative bronchopneumonia in foals. Although most foals likely are exposed to environmental R. equi within the 1st few days of life, only some develop R. equi pneumonia, and the basis of differences in susceptibility among foals currently is unknown. In this study, we investigated solute carrier family 11 member 1 (SLC11A1) gene sequences in the 5' untranslated region, exon 1, and a portion of intron 1 for variations in 3 equid species (horse, donkey, zebra) and compared variants within 3 independent horse breeding farms for associations with R. equi pneumonia by use of an age-matched case-control design. Seven novel variants in the 5'untranslated region were identified as specific for one or both of the non-horse equid species sampled. In addition, a single novel horse variant in the 5'untranslated region, -57C/T, was identified in 4 breeds. The -57C/T variant was found on 2 of the 3 farms with endemic R. equi pneumonia, representing 2 different horse breeds. Significant allelic and genotypic associations with susceptibility to R. equi pneumonia were observed for the -57C/T variant in foals from these farms. Although the functional impact of this novel variant remains to be determined, this study represents an important step in our understanding of natural resistance to R. equi foal pneumonia and other intracellular bacterial diseases affecting equids.     

Multi-carbohydrase enzymes improve feed energy in broiler diets containing standard or low crude protein

This study evaluated the effect of multi-carbohydrase (MC) on energy and nitrogen (N) balance and gene expression in broilers fed diets with different crude protein (CP) contents. The study employed a 2 × 2 factorial arrangement of treatments. The factors were presence or absence of MC, and standard (SCP) or low (LCP) dietary CP concentration. A 3-phase feeding program was used, including starter (0 to 7 d), grower (8 to 17 d) and finisher (18 to 28 d) phases. The study was undertaken in closed calorimetry chambers. Each of the 4 dietary treatments was replicated 8 times in total across 2 runs, with 2 birds per replicate (n = 64). Data for energy partitioning and N balance were collected from d 25 to 28. On d 28, birds were euthanized to collect muscle and intestinal tissue samples for gene expression. The results showed that the MC increased apparent metabolizable energy (AME, P < 0.01) and net energy (NE, P < 0.05), and reduced the feed conversion ratio (FCR, P < 0.01) in all diets. The proportion of energy retained as fat per total energy retention (REf/RE) was positively correlated with feed AME and NE (r = 0.541, P < 0.01 and r = 0.665, P < 0.001, respectively), suggesting that feed energy augmented with increased fat gain. Muscle ATP synthase subunit alpha (ATP5A1W) gene expression had a positive correlation with REf/RE and feed NE (r = 0.587, P < 0.001 and r = 0.430, P < 0.05, respectively). Similarly, muscle peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1A) expression was negatively correlated with weight gain and positively correlated with FCR (r = −0.451, P < 0.05 and r = 0.359, P < 0.05, respectively). These correlations show that over-expressions of muscle genes related to energy production reduce bird performance. This study demonstrated that MC increase dietary energy utilization, regardless of dietary CP concentration. However, the energy released by the enzymes increases feed energy-to-CP ratio, meaning there is excess energy that is then deposited as body fat. This suggests that supplemental MC in broiler feeds is beneficial if diets are formulated to contain marginal energy levels.     

Temporal Trends of Trace Metals in Sediment and Invertebrates from Stormwater Management Ponds

Stormwater ponds are an increasingly common feature in urban landscapes. Because these ponds retain runoff and particulate-bound contaminants from impervious surfaces, organisms inhabiting stormwater ponds may be exposed to elevated metal levels in sediments. This study evaluated temporal changes in sediment and macroinvertebrate Cu, Pb and Zn over an eleven-year period with specific attention to land use in pond watersheds. Sediment and invertebrate metal levels were quantified using atomic absorption spectrophotometry (1993 samples) or inductively coupled plasma mass spectrometry (2003–2004 samples). Sediment trace element levels did not significantly change from 1993 to 2003-2004 with the exception of Zn in ponds receiving runoff from highways, which increased from a mean of 32 mg kg^?1 in 1993 to 344 mg kg^?1 in 2003–2004. Sediment Pb and Cu generally remained below published threshold effects concentrations (TEC) except for two instances of elevated Cu in 2003–2004. Zn remained below the TEC in 1993 but exceeded the TEC in six ponds in 2003–2004. Trace metal body burdens varied among invertebrate groups, and to a lesser extent among land uses, but in both cases this variation was a function of year. In general, trace element body burdens were more similar among invertebrate groups or land use or both during 2003–2004 when compared to levels in 1993. Our results suggest sediment and invertebrate trace metal levels are at steady state in these stormwater management ponds and that risk to organisms inhabiting these ponds does not vary as a function of pond age.     

Effects of biochar,earthworms, and litter addition on soil microbial activity and abundance in a temperate agricultural soil

Biochar application to arable soils could be effective for soil C sequestration and mitigation of greenhouse gas (GHG) emissions. Soil microorganisms and fauna are the major contributors to GHG emissions from soil, but their interactions with biochar are poorly understood. We investigated the effects of biochar and its interaction with earthworms on soil microbial activity, abundance, and community composition in an incubation experiment with an arable soil with and without N-rich litter addition. After 37 days of incubation, biochar significantly reduced CO₂ (up to 43 %) and N₂O (up to 42 %), as well as NH₄ ⁺-N and NO₃ ^?-N concentrations, compared to the control soils. Concurrently, in the treatments with litter, biochar increased microbial biomass and the soil microbial community composition shifted to higher fungal-to-bacterial ratios. Without litter, all microbial groups were positively affected by biochar × earthworm interactions suggesting better living conditions for soil microorganisms in biochar-containing cast aggregates after the earthworm gut passage. However, assimilation of biochar-C by earthworms was negligible, indicating no direct benefit for the earthworms from biochar uptake. Biochar strongly reduced the metabolic quotient qCO₂ and suppressed the degradation of native SOC, resulting in large negative priming effects (up to 68 %). We conclude that the biochar amendment altered microbial activity, abundance, and community composition, inducing a more efficient microbial community with reduced emissions of CO₂ and N₂O. Earthworms affected soil microorganisms only in the presence of biochar, highlighting the need for further research on the interactions of biochar with soil fauna.     

Investigation of Differences between Field and Laboratory pH Measurements of National Atmospheric Deposition Program/National Trends Network Precipitation Samples

A study was undertaken to investigate differences between laboratoryand field pH measurements for precipitation samples collected from 135 weekly precipitation-monitoring sites in the National Trends Network from 12/30/1986 to 12/28/1999. Differences in pH between field and laboratory measurements occurred for 96% of samples collected during this time period. Differences between the two measurements were evaluated for precipitation samples collected before and after January 1994, when modifications to sample-handling protocol and elimination of the contaminating bucket o-ring used in sample shipment occurred. Median hydrogen-ion and pH differences between field and laboratory measurements declined from 3. 9 μeq L^-1 or 0. 10 pH units before the 1994 protocol change to 1. 4 μeq L^-1 or 0. 04 pH units after the 1994 protocol change. Hydrogen-ion differences between field and laboratory measurements had a high correlation with the sample pH determined in the field. The largest pH differences between the two measurements occurred for high-pH samples (>5. 6), typical of precipitation collected in Western United States; however low-pH samples (<5. 0) displayed the highest variability in hydrogen-ion differences between field and laboratory analyses. Properly screened field pH measurements are a useful alternative to laboratory pH values for trend analysis, particularly before 1994 when laboratory pH values were influenced by sample-collection equipment.     

Supplementation with grape seed polyphenols results in increased urinary excretion of 3-hydroxyphenylpropionic Acid, an important metabolite of proanthocyanidins in humans

Grape seed extract provides a concentrated source of polyphenols, most of which are proanthocyanidins. Polymeric proanthocyanidins are poorly absorbed in the small intestine of humans, and exposure may result from metabolism to phenolic acids by colonic bacteria. Any biological effects of proanthocyanidins may be due to the phenolic acid metabolites. Several phenolic acids have been identified as proanthocyanidin metabolites, but these may be derived from a range of other dietary sources. The aim of this study was to determine if 24-h urinary excretion of specific phenolic acids increased significantly and consistently following regular supplementation with grape seed extract. In a randomized, double-blind placebo-controlled trial, 69 volunteers received grape seed extract (1000 mg/day total polyphenols) or placebo for 6 weeks. Supplementation with grape seed polyphenols resulted in a consistent increase in the excretion of 3-hydroxyphenylpropionic acid (3-HPP, P < 0.001) and 4-O-methylgallic acid (P < 0.001) and a less consistent increase in the excretion of 3-hydroxyphenylacetic acid (P = 0.002). The observed increase in 3-HPP is in line with the suggestion that this compound is a major phenolic acid breakdown product of proanthocyanidin metabolism in vivo.