Probable mechanism of sexual dimorphism in insulin control of Drosophila heat stress resistance

Adult males of Drosophila species (Drosophila melanogaster L. and Drosophila virilis) show a lower tolerance to heat stress compared with females. The present study investigates the effects of RNA interference (RNAi) knockdown of the insulin‐like receptor in the corpus allatum of D. melanogaster males on dopamine metabolism and content, heat stress resistance and juvenile hormone metabolism. In male flies, the knockdown of insulin‐like receptor in the corpus allatum is shown to change metabolism of juvenile hormone but not dopamine. It is also shown that knockdown of the insulin‐like receptor in the corpus allatum results in a decrease of heat stress resistance in females but not males, and that juvenile hormone rescues this decrease. The results suggest that at least one of the ways in which insulin‐like growth factors affect heat stress resistance is by successive mediation through juvenile hormone and dopamine, which could lead to sexual dimorphism in the trait.     

Plasma prion protein concentration and progression of Alzheimer disease

Background/Objective: Recently, PrP^c has been linked to AD pathogenesis. Second, a relation of PrP^c plasma levels with cognitive status and decline of healthy elderly subjects has been reported. Therefore, we hypothesized baseline plasma levels of PrP^c to be associated with AD progression in cognitive and functional domains.Materials and Methods: AD patients (n = 84) were included into an observational study at time of diagnosis. Baseline plasma PrP^c levels were determined. Decline was assessed annually (mean follow-up time 3 years) with the aid of different standardized tests (MMSE, iADL, bADL, GDS, UPDRSIII). Multiple regression analyses were used to uncover potential associations between decline and PrP^c levels.Results: No association of PrP^c and decline could be established. Presence of diabetes mellitus was linked to slower deterioration. Intake of neuroleptic drugs or memantine was associated with faster progression.Conclusion: Plasma PrP^c at baseline could not be shown to be related to AD progression in this study. An interesting association of diabetes mellitus and decline warrants further investigation.     

A complex sensory organ in the nose skin of the prosimian primate Lemur catta

Most mammals have nose tips covered by glabrous skin, a labronasal area, or rhinarium. The surface of the rhinarium of Lemur catta has a dermatoglyphic pattern consisting of epidermal domes. Below the domes, epidermal pegs dip down into the dermis. In and below the tip of the epidermal peg, a complex sensory organ is found. It consists of an association of innervated Merkel cells, lamellate (Pacini‐like) bodies with a central nerve, and a ring of unmyelinated nerve endings in the epidermis. The Merkel cells are situated basally in the epidermis and the lamellated bodies just below the epidermis. The unmyelinated nerve endings related to the organ ascend in a circle straight through the epidermis ending below the corneal layer. From these nerve terminals, horizontal spikes enter the keratinocytes. The three components occur together forming an organ and are innervated from a common nerve plexus. The morphology of the complex sensory organ of the lemur shares most crucial components with Eimer's organs in moles, echidna, and platypus, while some structures are lacking, for example, the specific central pillar of keratinocytes, the cuticular cap, and a central unmyelinated fiber. The presence of the essentials of an Eimer's organ in many mammals suggests that a wider definition is motivated. J. Morphol. 276:649–656, 2015. © 2015 Wiley Periodicals, Inc.     

Single-walled carbon nanotube interactions with HeLa cells

This work concerns exposing cultured human epithelial-like HeLa cells to single-walled carbon nanotubes (SWNTs) dispersed in cell culture media supplemented with serum. First, the as-received CoMoCAT SWNT-containing powder was characterized using scanning electron microscopy and thermal gravimetric analyses. Characterizations of the purified dispersions, termed DM-SWNTs, involved atomic force microscopy, inductively coupled plasma – mass spectrometry, and absorption and Raman spectroscopies. Confocal microRaman spectroscopy was used to demonstrate that DM-SWNTs were taken up by HeLa cells in a time- and temperature-dependent fashion. Transmission electron microscopy revealed SWNT-like material in intracellular vacuoles. The morphologies and growth rates of HeLa cells exposed to DM-SWNTs were statistically similar to control cells over the course of 4 d. Finally, flow cytometry was used to show that the fluorescence from MitoSOX™ Red, a selective indicator of superoxide in mitochondria, was statistically similar in both control cells and cells incubated in DM-SWNTs. The combined results indicate that under our sample preparation protocols and assay conditions, CoMoCAT DM-SWNT dispersions are not inherently cytotoxic to HeLa cells. We conclude with recommendations for improving the accuracy and comparability of carbon nanotube (CNT) cytotoxicity reports.     

Novel insights into cyclooxygenases,linoleate diol synthases,and lipoxygenases from deuterium kinetic isotope effects and oxidation of substrate analogs

Cyclooxygenases (COX) and 8R-dioxygenase (8R-DOX) activities of linoleate diol synthases (LDS) are homologous heme-dependent enzymes that oxygenate fatty acids by a tyrosyl radical-mediated hydrogen abstraction and antarafacial insertion of O₂. Soybean lipoxygenase-1 (sLOX-1) contains non-heme iron and oxidizes 18:2n ? 6 with a large deuterium kinetic isotope effect (D-KIE). The aim of the present work was to obtain further mechanistic insight into the action of these enzymes by using a series of n ? 6 and n ? 9 fatty acids and by analysis of D-KIE. COX-1 oxidized C₂₀ and C₁₈ fatty acids in the following order of rates: 20:2n ? 6 > 20:1n ? 6 > 20:3n ? 9 > 20:1n ? 9 and 18:3n ? 3 ≥ 18:2n ? 6 > 18:1n ? 6. 18:2n ? 6 and its geometrical isomer (9E,12Z)18:2 were both mainly oxygenated at C-9 by COX-1, but the 9Z,12E isomer was mostly oxygenated at C-13. A cis-configured double bond in the n ? 6 position therefore seems important for substrate positioning. 8R-DOX oxidized (9Z,12E)18:2 at C-8 in analogy with 18:2n ? 6, but the 9E,12Z isomer was mainly subject to hydrogen abstraction at C-11 and oxygen insertion at C-9 by 8R-DOX of 5,8-LDS. sLOX-1 and 13R-MnLOX oxidized [11S-²H]18:2n ? 6 with similar D-KIE (~ 53), which implies that the catalytic metals did not alter the D-KIE. Oxygenation of 18:2n ? 6 by COX-1 and COX-2 took place with a D-KIE of 3–5 as probed by incubations of [11,11-²H₂]- and [11S-²H]18:2n ? 6. In contrast, the more energetically demanding hydrogen abstractions of the allylic carbons of 20:1n ? 6 by COX-1 and 18:1n ? 9 by 8R-DOX were both accompanied by large D-KIE (> 20).     

Hydrothermal treatment of naturally contaminated maize in the presence of sodium metabisulfite, methylamine and calcium hydroxide; effects on the concentration of zearalenone and deoxynivalenol

Fusarium toxin-contaminated ground maize was hydrothermally treated in the presence of different combinations of chemicals in order to simultaneously reduce zearalenone (ZEA) and deoxynivalenol (DON) concentrations. Treatments were carried out in a laboratory conditioner at 80 °C and 17 % moisture. Six different treatments were performed, consisting of 3 doses of methylamine (MMA; 2.5, 5 and 10 g/kg maize) at a constant dose of 5 g sodium metabisulfite (SBS)/kg, either with or without the addition of 20 g calcium hydroxide (Ca(OH)₂)/kg. The used maize was contaminated with approximately 45.99 mg DON/kg and 3.46 mg ZEA/kg. Without the addition of Ca(OH)₂, DON reductions reached approximately 82 % after 1-min treatment and the toxin disappeared nearly completely after 10 min when 2.5 or 5 g MMA were applied. ZEA concentrations were only marginally affected. In the presence of Ca(OH)₂, reductions in DON concentrations were lower, but were enhanced by increasing doses of MMA. ZEA concentrations were reduced by 72, 85 and 95 % within the first 5 min of the treatment at MMA dosages of 2.5, 5 and 10 g/kg maize, respectively. The application of SBS in combination with a strong alkaline during hydrothermal treatment seems to be a promising approach to simultaneously decontaminate even high amounts of DON and ZEA in ground maize and may contribute to reduce the toxin load of diets     

Dispersion of viable pig liver cells with collagenase.

Viable suspended hepatocytes were prepared from surgical biopsy specimens of pig and human liver by digestion with collagenase. Initial perfusion of the tissue through cannulated blood vessels with 0.5 mM EGTA followed by 0.2% collagenase gave the best results. 20−870 × 10⁶ cells of which 60–95 % excluded trypan blue were obtained from 5–30 g pig liver pieces, while results with human liver specimens were usually less satisfactory. In some experiments, however, viable cells, as judged by vital stain exclusion and ability to synthesize lipids were obtained in sufficient yield. In the pig hepatocytes glycerolipid synthesis from [³H] glycerol and oxidation and esterification of [¹⁴C] oleic acid had the same characteristics as those observed earlier in rat hepatocytes.