Drivers of cyanotoxin and taste-and-odor compound presence within the benthic algae of human-disturbed rivers.

Freshwater benthic algae form complex mat matrices that can confer ecosystem benefits but also produce harmful cyanotoxins and nuisance taste-and-odor (T&O) compounds. Despite intensive study of the response of pelagic systems to anthropogenic change, the environmental factors controlling toxin presence in benthic mats remain uncertain. Here, we present a unique dataset from a rapidly urbanizing community (Kansas City, USA) that spans environmental, toxicological, taxonomic, and genomic indicators to identify the prevalence of three cyanotoxins (microcystin, anatoxin-a, and saxitoxin) and two T&O compounds (geosmin and 2-methylisoborneol). Thereafter, we construct a random forest model informed by game theory to assess underlying drivers. Microcystin (11.9 ± 11.6 µg/m2), a liver toxin linked to animal fatalities, and geosmin (0.67 ± 0.67 µg/m2), a costly-to-treat malodorous compound, were the most abundant compounds and were present in 100 % of samples, irrespective of land use or environmental conditions. Anatoxin-a (8.1 ± 11.6 µg/m2) and saxitoxin (0.18 ± 0.39 µg/m2), while not always detected, showed a systematic tradeoff in their relative importance with season, an observation not previously reported in the literature. Our model indicates that microcystin concentrations were greatest where microcystin-producing genes were present, whereas geosmin concentrations were high in the absence of geosmin-producing genes. Together, these results suggest that benthic mats produce microcystin in situ but that geosmin production may occur ex situ with its presence in mats attributable to adsorption by organic matter. Our study broadens the awareness of benthic cyanobacteria as a source of harmful and nuisance metabolites and highlights the importance of benthic monitoring for sustaining water quality standards in rivers.

A Wild Yeast Laboratory Activity: From Isolation to Brewing.

Microbial fermentation is a common form of metabolism that has been exploited by humans to great benefit. Industrial fermentation currently produces a myriad of products ranging from biofuels to pharmaceuticals. About one-third of the world's food is fermented, and the brewing of fermented beverages in particular has an ancient and storied history. Because fermentation is so intertwined with our daily lives, the topic is easily relatable to students interested in real-world applications for microbiology. Here, we describe the curriculum for a guided inquiry-based laboratory course that combines yeast molecular ecology and brewing. The rationale for the course is to compare commercial Saccharomyces cerevisiae yeast strains, which have been domesticated through thousands of generations of selection, with wild yeast, where there is growing interest in their potentially unique brewing characteristics. Because wild yeasts are so easy to isolate, identify, and characterize, this is a great opportunity to present key concepts in molecular ecology and genetics in a way that is relevant and accessible to students. We organized the course around three main modules: isolation and identification of wild yeast, phenotypic characterization of wild and commercial ale yeast strains, and scientific design of a brewing recipe and head-to-head comparison of the performance of a commercial and wild yeast strain in the brewing process. Pre- and postassessment showed that students made significant gains in the learning objectives for the course, and students enjoyed connecting microbiology to a real-world application.

Enhanced Photothermal Treatment Efficacy and Normal Tissue Protection via Vascular Targeted Gold Nanocages.

A major challenge in photothermal treatment is generating sufficient heat to eradicate diseased tissue while sparing normal tissue. Au nanomaterials have shown promise as a means to achieve highly localized photothermal treatment. Toward that end, the synthetic peptide anginex was conjugated to Au nanocages. Anginex binds to galectin-1, which is highly expressed in dividing endothelial cells found primarily in the tumor vasculature. The skin surface temperature during a 10 min laser exposure of subcutaneous murine breast tumors did not exceed 43°C and no normal tissue damage was observed, yet a significant anti-tumor effect was observed when laser was applied 24 h post-injection of targeted nanocages. Untargeted particles showed little effect in immunocompetent, tumor-bearing mice under these conditions. Photoacoustic, photothermal, and ICP-MS mapping of harvested tissue showed distribution of particles near the vasculature throughout the tumor. This uptake pattern within the tumor combined with a minimal overall temperature rise were nonetheless sufficient to induce marked photothermal efficacy and evidence of tumor control. Importantly, this evidence suggests that bulk tumor temperature during treatment does not correlate with treatment outcome, which implies that targeted nanomedicine can be highly effective when closely bound/distributed in and around the tumor endothelium and extensive amounts of direct tumor cell binding may not be a prerequisite of effective photothermal approaches.

Dry flue gas desulfurization by-product application effects on plant uptake and soil storage changes in a managed grassland.

Environmental regulations mandate that sulfur dioxide (SO2) be removed from the flue gases of coal-fired power plants, which results in the generation of flue gas desulfurization (FGD) by-products. These FGD by-products may be a viable soil amendment, but the large amounts of trace elements contained in FGD by-products are potentially concerning. The objective of this study was to evaluate the effects of land application of a high-Ca dry FGD (DFGD) by-product on trace elements in aboveground biomass and soil. A high-Ca DFGD by-product was applied once at a rate of 9 Mg ha-1 on May 18, 2015 to small plots with mixed-grass vegetation. Soil and biomass were sampled prior to application and several times thereafter. Aboveground dry matter and tissue As, Co, Cr, Hg, Se, U, and V concentrations increased (P < 0.05) following application, but did not differ (P > 0.05) from pre-application levels or the unamended control within 3 to 6 months of application. Soil pH in the amended treatment 6 months after application was greater (P < 0.05) than in the unamended control. Soil Ca, S, and Na contents also increased (P < 0.05), following by-product application compared to the unamended control. High-Ca DFGD by-products appear to be useful as a soil amendment, but cause at least a temporary increase in tissue concentrations of trace elements, which may be problematic for animal grazing situations.

The effect of sexual maturity and egg production on skeletal muscle (pectoralis major and gastrocnemius) protein turnover in broiler breeder pure lines.

A study was conducted to evaluate the effect of sexual maturity on pectoralis major and gastrocnemius muscle protein turnover in broiler breeder pure lines. Protein turnover in skeletal muscle tissue was determined in 4 broiler breeder pure lines (Line A, Line B, Line C and Line D) at 22, 27, 33, 37, 44, and 50 wk of age. A completely randomized design with a factorial arrangement 4 × 6 (4 lines and 6 time periods (ages)) was used. There were 5 replicates per line/time and each hen represented a replicate. Five hens/line at each age were given an intravenous flooding-dose of 15N-phenylalanine (150 mM, 40 atom percent excess (APE) at a dose of 10 mL/kg. After 10 min, birds were euthanized using CO2 asphyxiation and the breast and leg muscle excised and snap frozen in liquid nitrogen for protein turnover analysis. Excreta was collected from each breeder for 3-methyl histidine (3-MH) analysis. There was a significant age effect for the breast muscle fractional synthesis rate (FSR), but no main effects (age and line) for leg muscle FSR. The FSR in breast muscle tissue decreased in hens from wk 22 (first egg) to wk 33 (peak egg production). There was a significant age effect on fractional breakdown rate (FBR) in breast and leg muscle. The FBR in breast muscle increased in hens from wk 22 to wk 33 and remained high through wk 37. Breast muscle FBR significantly decreased in hens from wk 37 to wk 50. The FBR in leg muscle tissue increased in hens from wk 33 to wk 37 and then decreased at wk 50. No line effect was seen for FSR or FBR. There is a large increase in skeletal muscle FBR during the transition for the pullet to sexual maturity with increases in skeletal muscle FBR in the breast and leg muscle through peak egg production. Protein turnover in skeletal muscle tissue is believed to be a source of nutrients for egg production.

Effect of white striping myopathy on breast muscle (Pectoralis major) protein turnover and gene expression in broilers.

WS: A study was conducted to evaluate the effect of white striping ( ) of broiler breast muscle ( Pectoralis major ) on protein turnover and gene expression of genes related to protein degradation and fatty acid synthesis. A total of 560 day-old male broiler chicks Cobb 500 were allocated in a total of 16 pens, 35 chicks per pen. A completely randomized design was conducted with a 2 × 3 factorial arrangement (2 scores: severe and normal, and 3 breast meat samples sites). At d 60, 20 birds were randomly selected, euthanized, and scored for white striping. Scoring was either normal ( , no WS) or severe ( ). Also, the same day, 17 birds (16 infused, one control) were randomly selected and infused with a solution of 15 N Phen 40% ( ). Breast muscle tissue was taken for gene expression analysis of the following genes: MuRF1, atrogin-1, IGF-1, insulin receptor ( ), fatty acid synthetase, and acetyl CoA carboxylase ( ). Each bird was humanely euthanized after 10 minutes of infusion and scored for WS (NORM or SEV). Samples of the breast muscle ( Pectoralis major ) were taken at different layers (3 samples per bird: ventral, medial, dorsal), along with a sample of excreta for 3-methylhistidine analysis. Out of the 16 breast samples taken, only 10 were selected for analysis based on the WS score (5 NORM and 5 SEV). No significant differences ( P > 0.05) were found in fractional synthesis rate ( ) between SEV WS, NORM and sample sites for breast meat. However, fractional breakdown rate ( ) was significantly higher in birds with SEV WS compared to NORM (8.2 and 4.28, respectively, P < 0.0001). Birds with SEV WS showed significantly higher ( P < 0.05) relative expression of MuRF1 and slightly higher ( P = 0.07) relative expression of atrogin-1 than the NORM birds. These birds also showed lower ( P < 0.05) relative expression of IGF-1 than NORM birds. Further studies are needed to better understand why birds with severe white striping are degrading more muscular protein and mobilizing more fat.

The effect of four different feeding regimens from rearing period to sexual maturity on breast muscle protein turnover in broiler breeder parent stock.

A study was conducted to evaluate the effect of four different feeding regimens on breast muscle protein turnover in broiler breeder Cobb-500 parent stock (PS) pullets and breeder hens. The four feeding regimens based on BW curves utilized for the study were as follows: Everyday feeding (STD-ED) (Cobb Standard BW curve), skip-a-day feeding (STD-SKIP) (Cobb Standard BW curve), lighter BW (LBW-SKIP) (BW curve 20% under), and heavier BW (HBW-SKIP) (BW curve 20% over). Each feeding regimen was provided to pullets from 4 wk to 21 wk of age. Protein turnover was determined in PS pullets/breeders at 6, 10, 12, 16, 21, 25, 31, 37, 46, and 66 wk of age. A completely randomized design was used with a 4 × 10 factorial arrangement (four feeding regimens, 10 ages), each pullet represented a replicate. Five pullets/breeders at each age were given an intravenous flooding-dose of 15N-Phe (15N phenylalanine 150 mM, 40 APE (atom percent excess)) at a dose of 10 mL/kg BW for the determination of fractional synthesis rate (FSR). After 10 min, birds were euthanized and the breast muscle (pectoralis major) excised for protein turnover and gene expression analysis. Excreta was collected from each pullet or breeder for 3-methylhistidine (3-MH) analysis. No feeding regimen affected protein turnover. There was an age effect for breast muscle FSR. The FSR in breast muscle of pullets significantly increased from 6 wk to 12 wk and then decreased significantly for 31 wk-old breeders. FSR in breeder breast muscle increased significantly from 31 wk to 66 wk. There was an age effect for breast muscle fractional breakdown rate (FBR). FBR in breast muscle significantly increased from 21 wk to 25 wk and 31 wk (peak egg production), then significantly decreased at 66 wk. The expression of the genes related to protein degradation (Atrogin-1, MURF-1) in breast muscle was significantly higher at peak egg production. Protein turnover in skeletal muscle tissue is believed to be a source of nutrients for egg production.

25-Hydroxycholecalciferol Enhances Male Broiler Breast Meat Yield through the mTOR Pathway.

BACKGROUND: In recent years, there has been a growing body of evidence indicating that replacing cholecalciferol (vitamin D3) with 25-hydroxycholecalciferol [25(OH)D3] through dietary supplementation enhances breast meat yield in broiler chickens. However, the underlying molecular mechanisms are still unknown. OBJECTIVE: We investigated the effect of 25(OH)D3 on male broiler growth performance (body weight, feed intake, feed conversion ratio, and breast meat yield), muscle protein synthesis, and the potential underlying molecular mechanisms. METHODS: Male Cobb 500 broiler chickens were divided into 4 body weight-matched groups and received a control diet with normal cholecalciferol (2760 IU/kg feed) for 42 d, a diet with high concentrations of cholecalciferol (5520 IU/kg feed) for 42 d, or a diet with 25(OH)D3 (5520 IU/kg feed) for 42 d (HyD-42). A fourth group consumed the HyD-42 for 21 d and then control feed for 21 d (HyD-21) (n = 360 birds, 12 replicates/treatment). Food and clean water were available for ad libitum consumption. At the end of the 42-d experiment, protein turnover was measured by phenylalanine flooding dose. Breast muscle tissues were collected and protein synthesis-related gene and protein expression were measured by real time polymerase chain reaction and Western blot, respectively. Functional studies were performed in vitro with the use of a quail myoblast (QM7) cell line. QM7 cells were treated with 2 doses (1 nM and 10 nM) of cholecalciferol or 25(OH)D3 alone or in combination with 100 nM rapamycin, and cell proliferation was determined by cell proliferation assay. Protein synthesis-related gene and protein expression were also determined. RESULTS: The HyD-42 increased 25(OH)D3 circulating concentrations by 126% (P < 0.05), enhanced breast meat yield (P < 0.05), and increased the fractional rate of protein synthesis by 3-fold (P < 0.05) compared with the control diet. Molecular analyses revealed that breast muscle from chickens consuming the HyD-42 expressed significantly higher concentrations of vitamin D receptor (VDR), phospho mechanistic target of rapamycin(Ser2481), phospho ribosomal P70 S6 kinase (RPS6K)(Thr421/Ser424), and antigen Ki-67 (Ki67) compared with the other groups. In line with the in vivo data, in vitro functional studies showed that cells treated with 25(OH)D3 for 24 h had increased VDR expression, and activated the mechanistic target of rapamycin (mTOR)/S6 kinase (S6K) pathway, enhanced Ki67 protein concentrations, and induced QM7 cell proliferation compared with untreated or cholecalciferol-treated cells. Blocking the mTOR pathway with rapamycin reversed these effects. CONCLUSION: Taken together, our findings provide evidence that the effects of 25(OH)D3 on male broiler breast muscle are likely mediated through the mTOR-S6K pathway.

Measurements of substrate oxidation using (13)CO 2-breath testing reveals shifts in fuel mix during starvation.

Most fasting animals are believed to sequentially switch from predominantly utilizing one metabolic substrate to another from carbohydrates, to lipids, then to proteins. The timing of these physiological transitions has been estimated using measures of substrate oxidation including changes in respiratory exchange ratios, blood metabolites, nitrogen excretion, or enzyme activities in tissues. Here, we demonstrate how (13)CO2-breath testing can be used to partition among the oxidation of distinct nutrient pools in the body (i.e., carbohydrates, lipids, and proteins) that have become artificially enriched in (13)C. Seventy-two Swiss Webster mice were raised to adulthood on diets supplemented with (13)C-1-L-leucine, (13)C-1-palmitic acid, (13)C-1-D-glucose, or no tracer. Mice were then fasted for 72 h during which [Formula: see text], [Formula: see text], δ(13)C of exhaled CO2, body temperature, body mass, and blood metabolites (i.e., glucose, ketone bodies, and triacylglycerols) were measured. The fasting mice exhibited reductions in body mass (29 %), body temperature (3.3 °C), minimum observed metabolic rates (24 %), and respiratory exchange ratio (0.18), as well as significant changes in blood metabolites; but these responses were not particularly indicative of changes in oxidative fuel mixture. Measurements of endogenous nutrient oxidation by way of (13)CO2-breath testing revealed a decrease in the rate of oxidation of carbohydrates from 61 to 10 % of the total energy expenditure during the first 6 h without food. This response was mirrored by a coincidental increase in rate of endogenous lipid oxidation from 18 to 64 %. A transient peak in carbohydrate oxidation occurred between 8 and 14 h, presumably during increased glycogen mobilization. A well-defined period of protein sparing between 8 and 12 h was observed where endogenous protein oxidation accounted for as little as 8 % of the total energy expenditure. Thereafter, protein oxidation continually increased accounting for as much as 24 % of the total energy expenditure by 72 h. This study demonstrates that (13)CO2-breath testing may provide a complementary approach to characterizing the timing and magnitude of sequential changes in substrate oxidation that occur during prolonged fasting and starvation.

Evaluating the potential use of myxomycetes as a source of lipids for biodiesel production.

The myxomycetes are a group of primitive phagotrophic eukaryotes characterized by a distinctive plasmodial stage that is well known for its rapid growth rate. In the present study, biomass and lipid production of several different species of myxomycetes were investigated. Physarum polycephalum was found to produce the highest amounts of both dry biomass (1.30g), and lipid (0.143g) per 20mL medium (equal to 65.0g biomass and 7.15g lipid per one liter of medium). Analysis of P. polycephalum lipids by thin layer chromatography (TLC) and fatty acid methyl esters (FAMES) by gas chromatography-mass spectrometry (GC-MS) techniques showed that the major lipid type is triglyceride (95.5%), followed by phospholipids (2.6%); diglyceride (0.92%) and monoglyceride (0.92%). Myxomycete lipids consist of three dominant fatty acids: oleic (20%), linoleic (33%), and palmitoleic (17%). These results suggest that P. polycephalum has considerable potential as a source of lipids for biodiesel production.

Stable isotopes may provide evidence for starvation in reptiles.

Previous studies have attempted to correlate stable isotope signatures of tissues with the nutritional condition of birds, mammals, fishes, and invertebrates. Unfortunately, very little is known about the relationship between food limitation and the isotopic composition of reptiles. We examined the effects that starvation has on delta13C and delta15N signatures in the tissues (excreta, carcass, scales, and claws) of six, distantly related squamate reptiles (gaboon vipers, Bitis gabonica; ball pythons, Python regius; ratsnakes, Elaphe obsoleta; boa constrictors, Boa constrictor; western diamondback rattlesnakes, Crotalus atrox, and savannah monitor lizards, Varanus exanthematicus). Analyses revealed that the isotopic composition of reptile carcasses did not change significantly in response to bouts of starvation lasting up to 168 days. In contrast, the isotopic signatures of reptile excreta became significantly enriched in 15N and depleted in 13C during starvation. The isotopic signatures of reptile scales and lizard claws were less indicative of starvation time than those of excreta. We discuss the physiological mechanisms that might be responsible for the starvation-induced changes in 13C and 15N signatures in the excreta, and present a mixing model to describe the shift in excreted nitrogen source pools (i.e. from a labile source pool to a nonlabile source pool) that apparently occurs during starvation in these animals. The results of this study suggest that naturally occurring stable isotopes might ultimately have some utility for characterizing nitrogen and carbon stress among free-living reptiles.