Filter Results
9412 results
Anthropogenic nitrogen is a ubiquitous environmental contaminant that is contributing to the degradation of freshwater, estuarine, and coastal ecosystems worldwide. The effects of environmental nitrate, a principal form of nitrogen, on the health of aquatic life is of increasing concern. We exposed female American alligators to three concentrations of nitrate (0.7, 10 and 100mg/L NO3-N) for a duration of five weeks and five months from hatch. We assessed growth, plasma sex steroid and thyroid hormone concentrations, and transcription levels of key genes involved in steroidogenesis (StAR, 3β-HSD, and P450scc) and hepatic clearance (Cyp1a, Cyp3a). Exposure to 100mg/L NO3-N for both five weeks and five months resulted in significantly increased plasma testosterone (T) concentrations compared with alligators in the reference treatment. No differences in 17β-estradiol, progesterone, or thyroid hormones were observed, nor were there differences in alligator weight or the mRNA abundance of steroidogenic or hepatic genes. Plasma and urinary nitrate concentrations increased with increasing nitrate treatment levels, although relative plasma concentrations of nitrate were significantly lower in five month, versus five week old animals, possibly due to improved kidney function in older animals. These results indicate that environmentally relevant concentrations of nitrate can increase circulating concentrations of T in young female alligators.
Data Types:
  • Slides
  • Image
  • Tabular Data
  • Document
Clinical and animal data indicate that serum 25-hydroxyvitamin D3 (25D) exerts an anabolic effect on bone while serum 1α,25-dihydroxyvitamin D3 (1,25D) stimulates bone mineral loss, although the mechanism responsible for these divergent actions is unknown. Biological effects of 25D on bone cells are dependent on the local conversion to 1,25D by the 25-hydroxyvitamin D-1α-hydroxylase enzyme, CYP27B1. Therefore, identification of possible differential activities of locally produced and exogenously supplied 1,25D in bone is likely to be informative for guiding optimal administration of vitamin D supplements for bone health. The mature osteoblastic cell line MLO-A5 expresses both the vitamin D receptor (Vdr) and Cyp27b1, and therefore is a suitable model for comparing the activities of 1,25D arising from these sources. Biologically, exogenous and endogenous sources of 1,25D have similar effects on proliferation, mineralisation and induction of a range of genes by MLO-A5 osteoblasts under osteogenic conditions although endogenous 1,25D levels are markedly lower than exogenous levels. Significant differences of pharmacokinetics and pharmacodynamics of 1,25D are evident between these two sources particularly in terms of modulating gene expression for Cyp24a1 and other genes largely expressed by embedded osteoblasts/osteocytes suggesting that endogenously synthesised 1,25D is more efficiently utilised by the differentiating osteoblast.
Data Types:
  • Slides
  • Image
Fermentation is a critical step in the processing of high quality cocoa; however, the biochemistry behind is still not well understood at a molecular level. In this research, using a non-targeted approach, the main metabolomic changes that occur throughout the fermentation process were explored. Genetically undefined cocoa varieties from Trinidad and Tobago (n=3), Costa Rica (n=1) and one clone IMC-67 (n=3) were subjected to spontaneous fermentation using farm-based and pilot plant controlled conditions. Samples were collected daily, and acetone/water/acetic acid (70/29.5/0.5%) extracts were obtained and measured using a UPLC-ESI+-Q-Tof-MS system. Analysis of pre-processed data, applying a PLS-DA model, highlighted significant differences between the three fermentation periods, observed at 0–2, 3–4 and 5–6days, respectively. Among the most discriminating metabolites, sucrose, flavanols such as (epi) catechin, procyanidin dimers and trimers, anthocyanins and oligopeptides ranging in size from 3 to 12 amino acids were tentatively identified. In general, flavanols and sugars tended to decrease throughout fermentation, whereas most oligopeptides increased to maximal levels after 3 to 4days of fermentation and decreased thereafter. These results shed new insight into cocoa fermentation optimization strategies and may also contribute to the development of novel alternatives for cocoa processing based on biochemical and functional values.
Data Types:
  • Slides
  • Image
  • Tabular Data
  • Document
Overexpression of the human vitamin D receptor (hVDR) transgene under control of the human osteocalcin promoter in FVB/N mice (OSVDR) was previously demonstrated to exhibit increased cortical and trabecular bone volume and strength due to decreased bone resorption and increased bone formation. An important question to address is whether the OSVDR bone phenotype persists on an alternative genetic background such as C57Bl6/J.
Data Types:
  • Slides
  • Image
  • Tabular Data
The molecular signaling processes involved the differentiation of the Müllerian duct (MD) into the female reproductive tract, or oviduct, in non-mammalian vertebrates are not well understood. Studies in mammals and birds indicate that steroid hormones play a role in this process, as the embryonic MD has been shown to be vulnerable to exogenous estrogens and progestins and environmental endocrine disrupting contaminants. In a previous study, developmental treatment with an estrogen receptor α (ERα) agonist, 4,4′,4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT), induced significant enlargement of the MD in alligator embryos incubated at a male-producing temperature, which was not observed in embryos treated with an estrogen receptor β (ERβ) agonist, 7-bromo-2-(4-hydroxyphenyl)-1,3-benzoxazol-5-ol (WAY 200070), or with 17β-estradiol (E2). In order to understand the role of estrogen signaling in female alligator oviduct development, we incubated eggs at a female-producing temperature and treated them with E2 and these ER selective agonists, PPT and WAY 200070, just prior to the thermosensitive window of sex determination. At stage 27, one stage prior to hatching, PPT induced significant enlargement of the MD with precocious development of secretory glands and connective tissue differentiation similar to characteristics of mature adult oviduct. PPT treatment in ovo increased mRNA expression of ERβ, progesterone receptor, androgen receptor and insulin-like growth factor 1 in MD at stage 27, while expression of ERα was decreased. Neither WAY 200070 nor E2 treatment induced these effects seen in PPT-treated MD. The results of this study provide insight into the critical factors for healthy reproductive system formation in this sentinel species, although further investigation is needed to determine whether the observed phenomena are directly due to selective stimulation of ERα or related to some other aspect of PPT treatment.
Data Types:
  • Slides
  • Image
  • Tabular Data
  • Document
Bile salts act as steroidal detergents in the gut, and could also interact with peptides and improve their bioavailability, although the mechanism is unclear. The occurrence of direct interaction between milk bioactive peptides, Ile-Asn-Tyr-Trp, Leu-Asp-Gln-Trp, and Leu-Gln-Lys-Trp, and different bile salts in the submicellar or micellar state was investigated by intrinsic fluorescence measurement and dynamic light scattering, above the critical micellar concentration, the latter being determined by isothermal titration calorimetry. The peptides form aggregates, spontaneously. In the presence of bile salts, some released peptide monomers were bound to the micellar surface. The lack of hydrogen bonding involving the C12OH group of the steroid skeleton, and the acidic function of some bile salts, might promote the interaction with the peptides, as could the lack of the C12OH group, rather than that of the C7OH group. At submicellar concentrations, sodium taurochenodeoxycholate and taurodeoxycholate readily interacted with the most hydrophobic peptide Ile-Asn-Tyr-Trp.
Data Types:
  • Slides
  • Image
  • Tabular Data
Ustilago maydis, an edible mushroom growing on maize (Zea mays), is consumed as the food delicacy huitlacoche in Mexico. A chlorogenic acid esterase from this basidiomycete was expressed in good yields cultivating the heterologous host Pichia pastoris on the 5L bioreactor scale (reUmChlE; 45.9UL−1). In contrast to previously described chlorogenic acid esterases, the reUmChlE was also active towards feruloylated saccharides. The enzyme preferred substrates with the ferulic acid esterified to the O-5 position of arabinose residues, typical of graminaceous monocots, over the O-2 position of arabinose or the O-6 position of galactose residues. Determination of kcat/Km showed that the reUmChlE hydrolyzed chlorogenic acid 18-fold more efficiently than methyl ferulate, p-coumarate or caffeate. Phenolic acids were released by reUmChlE from natural substrates, such as destarched wheat bran, sugar beet pectin and coffee pulp. Treatment of wheat dough using reUmChlE resulted in a noticeable softening indicating a potential application of the enzyme in bakery and confectionery.
Data Types:
  • Slides
  • Image
  • Tabular Data
In this work, a novel colorimetric nanosensor was developed for the selective detection of triazophos in environmental water and food samples using bifunctionalized silver nanoparticles (Ag NPs) as a probe. The Ag NPs were bifunctionalized with 3-mercaptopropinonic acid (MPA) and guanidineacetic acid (GAA) and used as a colorimetric probe for the selective sensing of triazophos via hydrogen bonding. The addition of triazophos into the bifunctionalized Ag NPs solution triggers the aggregation of bifunctionalized Ag NPs, inducing a color change from yellow to dark orange, which yields a red-shift in the surface plasmon resonance (SPR) peak of GAA-MPA-Au NPs. Results showed that the absorbance ratio (A550/A400) was linear with the logarithm of triazophos concentration in the range of 0.5–500μM and the detection limit (3σ) obtained by UV–visible spectra were 0.10 and 0.08μM using Tris-HCl pH 5.0 and sodium acetate pH 10.0 with addition of NaCl (0.4mM). The sensitivity of method was improved ∼85-fold using 0.4mM of NaCl as an ionic strength. This method was successfully applied to detect triazophos in water (tap, canal and river) and food (rice and apple) samples.
Data Types:
  • Slides
  • Image
  • Tabular Data
Selected physical properties of bentonitic clays in the north Western Desert, Egypt were investigated to assess their potential use in industrial applications. Assessment tests included specific surface area (SSA), swelling index (SI), green (GCS) and dry (DCS) compressive strengths, rheological properties, and filtrate volume. The impact of Na-activation on swelling index and rheological properties was also considered. SSA, SI after Na-activation, GCS, and rheological properties were highly correlated with smectite content and a modified AgTU-CEC. Mineral impurities greatly influenced the physical properties. Quartz and feldspars reduced the rheological properties and increased the water loss. Halite and colloidal iron oxides increased swelling index and enhanced rheological properties. DCS was greatly influenced by the percentage of added water and kaolinite abundance. Na-activation improved the swelling index and rheological properties of halite-poor samples. The swelling index of Na-activated samples was a useful tool for determining the quality and grade of bentonitic clays.
Data Types:
  • Slides
  • Image
  • Tabular Data
Helicoverpa armigera is one of the major crop pests and is less amenable to current pest control approaches. RNA interference (RNAi) is emerging as a potent arsenal for the insect pest control over current methods. Here, we examined the effect on growth and development in H. armigera by targeting various enzymes/proteins such as proteases like trypsins (HaTry2, 3, 4 and 6), chymotrypsin (HaChy4) and cysteine protease like cathepsin (HaCATHL); glutathione S-transferases (HaGST1a, 6 and 8); esterases (HaAce4, HaJHE); catalase (HaCAT); super-oxide-dismutase (HaCu/ZnSOD); fatty acid binding protein (HaFabp) and chitin deacetylase (HaCda5b) through dsRNA approach. Significant downregulation of cognate mRNA expression and reduced activity of trypsin and GST-like enzyme were evident upon feeding candidate dsRNAs to the larvae. Among these, the highest mortality was observed in HaAce4 dsRNA fed larvae followed by HaJHE; HaCAT; HaCuZnSOD; HaFabp and HaTry3 whereas remaining ones showed relatively lower mortality. Furthermore, the dsRNA fed larvae showed significant reduction in the larval mass and abnormalities at the different stages of H. armigera development compared to their control diets. For example, malformed larvae, pupae and moth at a dose of 60μg/day were evident in high number of individual insects fed on dsRNA containing diets. Moreover, the growth and development of insects and moths were retarded in dsRNA fed larvae. These findings might provide potential new candidates for designing effective dsRNA as pesticide in crop protection.
Data Types:
  • Slides
  • Image
  • Tabular Data
  • Document
5