An Ustilago maydis Mutant Partially Blocked in P45014DM Activity Is Hypersensitive to Azole Fungicides

An Ustilago maydis ergosterol biosynthesis mutant (A14) which is partially blocked in sterol 14alpha-demethylase (P45014DM) activity is described. This mutant accumulated the abnormal 14alpha-methyl sterols, eburicol, 14alpha-methylfecosterol, and obtusifoliol, along with significant amounts of ergosterol. Although the A14 mutant grew nearly as well as the wild type, it was impaired in cell extension growth, which indicated a dysfunction in apical cell wall synthesis. The mutant was also found to be hypersensitive to the azole fungicides penconazole and tebuconazole.     

Relative resistance to 1,25-dihydroxyvitamin D3 in a keratinocyte model of tumor progression.

We have examined the effect of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on mitogen-stimulated growth and on c-myc proto-oncogene expression in a keratinocyte model of tumor progression. A dose-dependent inhibition of cell growth by 1,25-(OH)2D3 was demonstrated in both established (HPK1A) and malignant (HPK1A-ras) cells. However, this inhibition was observed with the addition of 1,25-(OH)2D3 at a higher concentration in HPK1A-ras cells than in HPK1A cells. Cell cycle analysis revealed a blockage of the normal progression of the cell cycle from G0 to S phase in the presence of 1,25-(OH)2D3. A higher concentration of 1,25-(OH)2D3 was required in HPK1A-ras cells to overcome the mitogen-stimulated progression into S phase, when compared with HPK1A cells. Analysis of c-myc messenger RNA revealed a strong inhibition of its expression at early time points with higher concentrations of 1,25-(OH)2D3 being required to obtain an inhibition in HPK1A-ras cells similar to that obtained in HPK1A cells. 1,25-(OH)2D3 receptor characterization by sucrose gradient analysis and equilibrium binding demonstrated the presence of a single 3.7 S protein with similar receptor numbers and affinity in both cell lines. These observations therefore demonstrate that an alteration of the growth inhibitory response to 1,25-(OH)2D3 occurs when keratinocytes acquire the malignant phenotype and suggest that the alteration lies beyond the interaction of the ligand with its receptor. In addition, relative resistance to 1,25-(OH)2D3 was also observed in the expression of the cell-cycle associated oncogene c-myc. These studies may therefore have important implications in vivo in the development and growth of epithelial cell cancers.     

Hexazonium pararosaniline as a fixative for animal tissues

Hexazonium pararosaniline is a valuable reagent that has been used in enzyme activity histochemistry for 50 years. It is an aqueous solution containing the tris-diazonium ion derived from pararosaniline, an aminotriarylmethane dye, and it contains an excess of nitrous acid that was not consumed in the diazotization reaction. Other investigators have found that immersion for 2 min in an acidic (pH 3.5) 0.0015 M hexazonium pararosaniline solution can protect cryostat sections of unfixed animal tissues from the deleterious effects of aqueous reagents such as buffered solutions used in immunohistochemistry, while preserving specific affinities for antibodies. In the present investigation hexazonium pararosaniline protected lymphoid tissue and striated muscle against the damaging effects of water or saline. The same protection was conferred on unfixed sections treated with dilute nitrous or hydrochloric acid in concentrations similar to those in hexazonium pararosaniline solutions. Model tissues (solutions, gels or films containing gelatin and/or bovine albumin) responded predictably to well known cross-linking (formaldehyde) or coagulant (mercuric chloride) fixatives. Hexazonium pararosaniline solutions prevented the dissolution of protein gels in water only after 9 or more days of contact, during which time considerable swelling occurred. It is concluded that there is no evidence for a “fixative” action of hexazonium pararosaniline. The protective effect on frozen sections of unfixed tissue is attributable probably to the low pH of the solution.     

Évaluation fonctionnelle par TEP 18F-FDopa des paragangliomes et phéochromocytomes non métastatiques : impact de la localisation lésionnelle et du statut génétique

ObjectiveParaganglioma (PGL) and pheochromocytoma (PCC) are neuroendocrine tumors most often benign associated with hereditary syndromes in about 30% of cases. This study aims to define the impact of tumor location and patient genotype on the clinical value of ¹⁸F-FDopa PET by assessing in detail the false negative occurrences.Patients and methodsA retrospective study was conducted on a cohort of 53 cases with non-metastatic sporadic or inherited PGL/PCC (SDHx or VHL related syndromes), investigated with ¹⁸F-FDopa PET.ResultsOverall detection sensitivity of ¹⁸F-FDopa PET was 88%. Seventy-three lesions were found using this technique, including 49 head-and-neck PGL (HNP), two thoracic PGL (1 sympathetic and 1 parasympathetic), eight extra-adrenal retroperitoneal PGL and 15 PCC. The 10 missed lesions were seven extra-adrenal abdominal PGL (2 SDHB, 2 SDHD), two HNP (1 sporadic, 1 SDHD) and one PCC (1 SDHD).Conclusion¹⁸F-FDopa PET is a sensitive technique for the evaluation of non-metastatic head and neck and adrenal PGLs. Exploration of extra-adrenal retroperitoneal PGL associated with SDHB or SDHD syndrome is the main limitation of this technique, encouraging the use of alternative functional imaging modalities like FDG-PET. Negativity of ¹⁸F-FDopa PET in the initial assessment of a PGL should prompt to search for a SDHx mutation.     

Economic evaluation of water loss saving due to the biological control of water hyacinth at New Year’s Dam,Eastern Cape province,South Africa

Water hyacinth Eichhornia crassipes is considered the most damaging aquatic weed in the world. However, few studies have quantified the impact of this weed economically and ecologically, and even fewer studies have quantified the benefits of its control. This paper focuses on water loss saving as the benefit derived from biological control of this plant between 1990 and 2013 at New Year’s Dam, Alicedale, Eastern Cape, South Africa. Estimates of water loss due to evapotranspiration from water hyacinth vary significantly; therefore, the study used three different rates, high, medium and low. A conservative raw agriculture value of R 0.26 per m³ was used to calculate the benefits derived by the water saved. The present benefit and cost values were determined using 10% and 5% discount rates. The benefit/cost ratio at the low evapotranspiration rate was less than one, implying that biological control was not economically viable but, at the higher evapotranspiration rates, the return justified the costs of biological control. However, at the marginal value product of water, the inclusion of the costs of damage to infrastructure, or the adverse effects of water hyacinth on biodiversity, would justify the use of biological control, even at the low transpiration rate.     

The Tau/A152T mutation,a risk factor for frontotemporal‐spectrum disorders,leads to NR2B receptor‐mediated excitotoxicity

We report on a novel transgenic mouse model expressing human full‐length Tau with the Tau mutation A152T (hTau^AT), a risk factor for FTD‐spectrum disorders including PSP and CBD. Brain neurons reveal pathological Tau conformation, hyperphosphorylation, mis‐sorting, aggregation, neuronal degeneration, and progressive loss, most prominently in area CA3 of the hippocampus. The mossy fiber pathway shows enhanced basal synaptic transmission without changes in short‐ or long‐term plasticity. In organotypic hippocampal slices, extracellular glutamate increases early above control levels, followed by a rise in neurotoxicity. These changes are normalized by inhibiting neurotransmitter release or by blocking voltage‐gated sodium channels. CA3 neurons show elevated intracellular calcium during rest and after activity induction which is sensitive to NR2B antagonizing drugs, demonstrating a pivotal role of extrasynaptic NMDA receptors. Slices show pronounced epileptiform activity and axonal sprouting of mossy fibers. Excitotoxic neuronal death is ameliorated by ceftriaxone, which stimulates astrocytic glutamate uptake via the transporter EAAT2/GLT1. In summary, hTau^AT causes excitotoxicity mediated by NR2B‐containing NMDA receptors due to enhanced extracellular glutamate.     

In vitro evaluation of native entomopathogenic fungi and neem (Azadiractha indica) extracts on Spodoptera frugiperda

The control of Spodoptera frugiperda is based on synthetic insecticides, so some alternatives are the use of entomopathogenic fungi (EF) and neem extract. The objective of the study was to evaluate in vitro effectiveness of native EF and neem extracts on S. frugiperda larvae. Six EF were identified by DNA sequencing of ITS regions from three EF (Fusarium solani, Metarrhizium robertsii, Nigrospora spherica and Penicillium citrinum). They were evaluated in concentrations of 1 × 10⁸ spores/ mL. In addition, a second bioassay was carried out evaluating only F. solani, M. robertsii and N. sphaerica and the addition of vegetable oil. On the other hand, extraction of secondary metabolites from neem seed (Azadirachta indica) was carried out by performing, mass (g) and solvent volume (mL ethanol and water) combinations, which were subjected to microwaves and ultrasound. Subsequently, these extracts were evaluated in concentrations of 3%, 4% and 5%. A survival analysis was performed for each of the bioassays. With respect to the results of the first bioassay, F. solani obtained a probability of survival of 0.476 on the seventh day, while in the second bioassay, M. robertsii obtained 0.488 survival probability. This suggests that the expected percentage of larvae that stay alive on the sixth day is 48.8%. However, in the evaluation of the neem extract the combination 1:12/70% to 4% caused 84% mortality of larvae. The use of native HE and neem extracts has potential for the control of S. frugiperda.