Endophytic fungi isolated from plants present in a mine tailing facility show a differential growth response to lead.

Plants growing in metal-polluted sites can be a source of micro-organisms suitable for bio-assisted phytoremediation strategies. In this work, three endophytic fungi from the roots of Poa stuckertii and Poa pratensis, two grasses that naturally colonize a Lead-Zinc tailing storage facility in Southern Chile, were isolated and identified. The leachate of the tailing sands showed a Pb content of 1·36 ± 0·71 ppm, and a pH of 7·3. By amplifying the ITS1/ITS4 region of fungal ribosomal DNA, the isolates were identified as Bjerkandera sp., Microdochium sp. and Sarocladium sp. When the growth media was supplemented with 50 ppm of Pb at pH 4·5, Microdochium sp. showed an 80% decrease in the biomass, but the biomass production of Bjerkandera sp. and Sarocladium sp. was not affected by the same treatment. The accumulation of Pb in Microdochium sp. increased as a function of the concentration of the metal in the growth media, between 48·3 and 241·3 µmol l-1 . We showed that two Poaceae plants growing on a Lead-Zinc tailing storage facility are a source of endophyte fungi and that Pb had a differential effect on the growth of the isolated fungi independent of the plant of origin.

Characterization of the fungitoxic activity on Botrytis cinerea of the aristolochic acids I and II.

The fungitoxic effect of aristolochic acids I and II on mycelial growth and conidial germination of Botrytis cinerea was analysed. Aristolochic acid I had a higher effect on mycelial growth of B. cinerea than aristolochic acid II with IC50 value of 18·7 and 57·0 µg ml-1 , respectively. These compounds did not affect the conidia germination. Also, the effect of both compounds on DNA and plasmatic membrane integrity of B. cinerea was studied. Only aristolochic acid II was able to cause damage to the integrity of the plasmatic membrane. When the fungus was incubated with a mixture of these compounds, degradation of DNA was observed. Finally, biotransformation products were not detected in the culture broth when B. cinerea was incubated in the presence of the aristolochic acids. Studies of structural characteristics that increase the antifungal effect of compounds against B. cinerea will permit to design new molecules to control this phytopathogenic fungus. SIGNIFICANCE AND IMPACT OF THE STUDY: The fungitoxic effect on Botrytis cinerea of aristolochic acids I and II was characterized. The only structural difference among these compounds is a methoxy group at carbon 8. However, despite their structural similarity, the fungitoxic effect of aristolochic acid I was higher than the effect of aristolochic acid II. This result suggests that the methoxy group is important for the fungitoxic activity of these compounds on B. cinerea.

Alteration of oxidative phosphorylation as a possible mechanism of the antifungal action of p-coumaric acid against Botrytis cinerea.

AIMS: The aim of this study was to analyse the mechanism of action of p-coumaric acid against isolate B05·10 of Botrytis cinerea. For this purpose, the effect of this compound on cell membrane, cell wall and oxidative phosphorylation was determined. Induction of oxidative stress triggered by this compound was also studied. METHODS AND RESULTS: p-coumaric acid showed antifungal effect on the mycelial growth. Additionally, the compound was able to retard the germination of Botrytis cinerea conidia. The mechanism of action of this compound was analysed using fluorescent probes. p-Coumaric acid did not affect the integrity of cell wall and plasmatic membrane and neither produced oxidative stress. Finally, it was shown that the compound produced an increase in oxygen consumption. CONCLUSIONS: p-coumaric acid performs as a mitochondrial uncoupler in B. cinerea. Its role as an uncoupler of oxidative phosphorylation could be explained to its acidic, nonpolar and planar characteristics. These structural and chemical characteristics would favour ability of p-coumaric acid to pass through cellular membranes. SIGNIFICANCE AND IMPACT OF THE STUDY: Plant secondary metabolites can be used as an alternative way to control phytopathogenic fungi. The knowledge of the action mechanism of these compounds can contribute to design modified molecules with higher antifungal activity.

Hipertiroidismo gestacional: análisis a propósito de un asociado a mola / Gestational hyperthyroidism associated to molar pregnancy: a case report

We report a 18 years old woman that was admitted with a history of four days of cardiac failure with acute pulmonary edema, high blood pressure, left ventricular dilatation and moderate to severe systolic dysfunction. Twenty four hours after admission she had a miscarriage, expelling a mole. The diagnosis of hyperthyroidism caused by a mole and early pre eclampsia was confirmed and the patient was managed with diuretics and dopamine. Symptoms abated, thyroid function tests, cardiac function and size returned to normal values and the patient was discharged asymptomatic, ten days after admission

DNA polymerases from the extremely thermophilic bacterium Thermus thermophilus HB-8.

Three DNA polymerase isoenzymes, which have been called A, B and C, were purified from Thermus thermophilus HB-8. These enzymes can be separated by chromatography (pH 7.5) on phosphocellulose and DNA-agarose. Their relative molecular masses, as determined by glycerol gradient centrifugation, fall in the range of 110000-120000. The three of them are devoid of exonuclease activity. Species A, B and C differ in their sensitivity towards N-ethylmaleimide (A greater than B greater than C) and urea (A greater than B = C) and also in their stability at high temperature (90 degrees C) (B greater than C greater than A). In addition, these enzymes can be distinguished utilizing various templates under different conditions. Thus, with activated DNA and Mg2+ as a cofactor, the highest incorporation is obtained at 50 degrees C with enzyme A and at 63 degrees C with enzymes B and C. If Mg2+ is replaced by Mn2+, the optimal temperatures remain unchanged, but enzyme A is stimulated twofold, while the activities of enzymes B and C decrease to one-half. On the other hand, with either poly(dA) X (dT)10 or poly(dA-dT) and Mg2+, enzyme A is inactive and enzyme C is severalfold more active than enzyme B. With the former synthetic template, optimal temperatures are 50 degrees C (enzyme C) and 40 degrees C (enzyme B), while with poly(dA-dT) they both work best at 63 degrees C. In turn, only enzyme C is able to utilize poly(rA) X (dT)10, although only with Mn2+ as a cofactor.