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Zanieczyszczenia gleb i wód produktami ropopochodnymi mogą być niwelowane przez żywe organizmy. Do rozkładu i przekształcania szkodliwych dla środowiska związków chemicznych, m.in. węglowodorów i metali ciężkich, czyli bioremediacji, wykorzystuje się przede wszystkim bakterie, ze względu na dużą liczebność ich populacji i szybki wzrost. Autorka omawia zagadnienie na przykładzie organizmów zimnolubnych
Bacteriological infections and mycoses have recently been on the increase. They are increasingly more difficult to combat because of the ever-rising resistance of the strains to the so-far effective antibiotics. The increase in mycosis cases should not be attributed to health-care factors alone. Agriculture and food-processing industries play a huge part. The authors deal with the strategies deployed in combating fungal pathogens.
Szesnaście szczepów bakterii wyizolowanych z próbek wody i gleby ze Spitsbergenu (Arktyka) zidentyfikowano do gatunku na podstawie sekwencjonowania podjednostki 16S rRNA. Trzynaście szczepów określono jako Pseudomonas fluorescens, a trzy jako Pseudomonas syringae. Przebadano aktywności proteolityczne i lipolityczne oznaczonych szczepów. Aktywność proteolityczną wykazywały wszystkie badane mikroorganizmy i wahała się ona od 58,5 do 139,6 U/ml. Aktywność lipolityczną wykazywało tylko sześć bakterii, przy czym lipazy trzech z tych szczepów (BD1, BD5 oraz BD25) rozkładały ester sorbitolu (Tween 80), a lipazy z dwóch mikroorganizmów (BD22 i BD30) rozkładały palmitynian p-nitrofenolu. Tylko szczep BD3 wydzielał lipazy aktywne w obydwóch stosowanych testach.
Seasonal changes in lipid droplet size and lipid peroxidation in the brown adipose tissue (BAT) of wild bank voles were examined. In addition, a role of photoperiod in these changes was studied; bank voles were held from the birth under long photoperiod (LP) for 12 weeks, and then half of them was transferred to short photoperiod (SP) for 6 weeks and another one remained under LP. In the wild bank voles the absolute BAT weight was seasonally constant, while the significant differences in the lipid droplet size were observed. The smallest lipid droplets (mean, 11 μm2) were seen in winter; they increased by 30 % in spring and reached the highest size (24 μm2) in summer. Lipid peroxidation in the BAT did not differ significantly between the seasons, although high intraseason variation of this process was noted. The laboratory experiment revealed that the size of lipid droplets was determined by photoperiod; SP induced 13-fold decrease, and continuous exposure to LP brought about a further 2.5-fold increase in the size of lipid droplets. Conversely, a significant decrease in lipid peroxidation was seen in LP bank voles in comparison with the SP animals. The data indicate that short photoperiod is responsible for the small size of lipid droplets in the BAT of bank voles during winter, which may be a necessary requirement for high thermogenic capacity of the tissue. Photoperiod appears also to affect lipid peroxidation in the BAT of these animals.
Quinacrine was used to visualize the intracellular pH changes in the yeast strain Saccharomyces cerevisiae RXII occurring after exposure to four recently-synthesized lysosomotropic drugs: DM-11, PY-11, PYG-12s and DMAL-12s. The cells took up quinacrine, mostly accumulating it in their vacuoles. DM-11 and PY-11 gave rise to diffuse quinacrine fluorescence throughout the cells, with the vacuoles staining to a somewhat greater extent than the cytosol. This quinacrine-detected overall acidification of the cell interior is very probably caused by blocking of plasma membrane H+-ATPase. PYG-12s gave rise to a strong vacuolar accumulation of the dye. Like the vacuolar ATPase inhibitor bafilomycin A1, DMAL-12s strongly lowered the intensity of quinacrine fluorescence. Owing to its low pKa, it can penetrate rapidly into the cells and may inhibit vacuolar H+-ATPase and prevent quinacrine-detectable vacuolar acidification without causing strong cell acidification. Since these drugs were found to penetrate into the cells, their lack of effect may reflect a higher resistance of both plasma membrane H+-ATPase and vacuolar ATPase to the drugs. Our data indicate that the lysosomotropic drugs under study have a dual action. On entering the cell, they cause intracellular acidification, very probably by inhibiting plasma membrane H+-ATPase and curtailing active proton pumping from the cells. Furthermore, they interfere with the function of V-type ATPase, causing vacuolar alkalinization and eventually cell death.
The lysosomotropic action of the compounds DM-11 and DMAL-12s against Saccharomyces cerevisiae, Schizosaccharomyces pombe and Candida albicans is species- and pH-dependent. At pH 6.0, DMAL-12s is less effective against S. cerevisiae and S. pombe but more effective against C. albicans than DM-11. At pH 8.0, DMAL-12s strongly inhibits the growth of S. cerevisiae but has only a marginal effect on the resistant C. albicans. S. pombe did not grow at pH 8.0. As shown by quinacrine accumulation, DM-11 causes a general intracellular acidification in all three species, while with DMAL-12s, the acidification is marginal. Morphological changes caused by DMAL-12s in S. cerevisiae affect the cell interior but not surface structures, while S. pombe cells exhibit a thickened and wrinkled cell wall, shrunken protoplast and "grainy" plasma membrane. A large number of blisters resembling lipid droplets were observed inside S. cerevisiae and S. pombe vacuoles. The high susceptibility of S. pombe cells to the action of DM-11 and DMAL-12s contrasts with the low sensitivity of S. pombe H+-ATPase to the agents. In our C. albicans isolate, DMAL 12s did not have an effect on cell morphology and appeared to be unable to penetrate the cells, especially at pH 8.0.
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