Ecology of dermatophytes and other keratinophilic fungi in swimming pools and polluted and unpolluted streams

The biodiversity and richness of keratinophilic fungal communities including dermatophytes were assessed in three stream sites and three swimming pools in the Nablus district in Palestine, using hair baiting (HBT) and surface dilution plate (SDP) techniques, over 8- and 6-month periods, respectively. The effect of wastewater effluent and selected ecological factors on these fungi in relation to species diversity and population densities were also considered. Fifty keratinophilic fungal species were recovered from the aquatic habitats studied, of which 42 were recovered from stream sites and 22 from swimming pools. Of these fungi 6 were either dermatophytes (Microsporum gypseum, and Trichophyton mentagrophytes) or dermatophyte related species (Chrysosporium merdarium, Ch. tropicum, Ch. keratinophilum and T. terrestre). The most frequently isolated species in the three pools were Acremonium strictum and Cladosporium cladosporioides, using Sabouraud dextrose agar medium (SDA). The most abundant species were Acr. strictum, and Aspergillus flavus. However, only 4 species were isolated using the SDA medium amended with 5-flurocytosine (5-FC). The most frequent and abundant species in the three stream sites using SDA medium were Geotricum candidum, and Penicillium chrysogenum. The most frequent species in the three sites using the 5-FC medium, was Paecilomyces lilacinus. Using HBT, the most abundant and frequent species in the three stream sites were G. candidum, and Pa. lilacinus, on SDA medium, and Pa. lilacinus, and Gliocladium nigrovirens on the 5-FC medium. The 5-FC medium was more suitable for the isolation of dermatophytes and closely related species than the SDA medium; 6 were recovered on 5-FC, whereas only one on the SDA medium. Variation in the levels of keratinophilic fungal populations from the three stream sites sampled 5 times over an 8-month period, followed comparable fluctuation patterns. Wastewater affected fungal population densities with the highest levels in the un-polluted stream sites, and lowest in the heavily polluted sites. Swimming pools, polluted and un-polluted stream sites were found to be rich in pathogenic and potentially pathogenic fungi.     

Ca2+-overload inhibits the cardiac SR Ca2+-calmodulin protein kinase activity

There is increasing evidence to suggest that Ca2+-calmodulin dependent protein kinase (CaMK) regulates the sarcoplasmic reticulum (SR) function and thus plays an important role in modulating the cardiac performance. Because intracellular Ca2+-overload is an important factor underlying cardiac dysfunction in a heart disease, its effect on SR CaMK was examined in the isolated rat heart preparations. Ca2+-depletion for 5 min followed by Ca2+-repletion for 30 min, which is known to produce intracellular Ca2+-overload, was observed to attenuate cardiac function as well as SR Ca2+-uptake and Ca2+-release activities. Attenuated SR function in the heart was associated with reduced CaMK phosphorylation of the SR Ca2+-cycling proteins such as Ca2+-release channel, Ca2+-pump ATPase, and phospholamban, decreased CaMK activity, and depressed levels of SR Ca2+-cycling proteins. These results indicate that alterations in cardiac performance and SR function following the occurrence of intracellular Ca2+-overload may partly be due to changes in the SR CaMK activity.     

Relaxation kinetics and the glassiness of proteins: the case of bovine pancreatic trypsin inhibitor

Folded proteins may be regarded as soft active matter under physiological conditions. The densely packed hydrophobic interior, the relatively molten hydrophilic exterior, and the spacer connecting these put together a large number of locally homogeneous regions. For the case of the bovine pancreatic trypsin inhibitor, with the aid of molecular dynamics simulations, we have demonstrated that the kinetics of the relaxation of the internal motions is highly concerted, manifesting the protein's heterogeneity, which may arise from variations in density, local packing, or the local energy landscape. This behavior is characterized in a stretched exponential decay described by an exponent of approximately 0.4 at physiological temperatures. Due to the trapped conformations, configurational entropy becomes smaller, and the associated stretch exponent drops to half of its value below the glass transition range. The temperature dependence of the inverse relaxation time closely follows the Vogel-Tamman-Fulcher expression when the protein is biologically active.     

Protein kinase C zeta nuclear translocation mediates the occurrence of radioresistance in friend erythroleukemia cells

Friend erythroleukemia cells require high doses (15 Gy) of ionizing radiation to display a reduced rate of proliferation and an increased number of dead cells. Since ionizing radiation can activate several signaling pathways at the plasma membrane which can lead to the nuclear translocation of a number of proteins, we looked at the intranuclear signaling system activated by Protein Kinases C, being this family of enzymes involved in the regulation of cell growth and death. Our results show an early and dose-dependent increased activity of zeta and epsilon isoforms, although PKC zeta is the only isoform significantly active and translocated into the nuclear compartment upon low (1.5 Gy) and high (15 Gy) radiation doses. These observations are concomitant and consistent with an increase in the anti-apoptotic protein Bcl-2 level upon both radiation doses. Our results point at the involvement of the PKC pathway in the survival response to ionizing radiation of this peculiar cell line, offering PKC zeta for consideration as a possible target of pharmacological treatments aimed at amplifying the effect of such a genotoxic agent.     

Sply regulation of sphingolipid signaling molecules is essential for Drosophila development

Sphingosine-1-phosphate is a sphingolipid metabolite that regulates cell proliferation, migration and apoptosis through specific signaling pathways. Sphingosine-1-phosphate lyase catalyzes the conversion of sphingosine-1-phosphate to ethanolamine phosphate and a fatty aldehyde. We report the cloning of the Drosophila sphingosine-1-phosphate lyase gene (Sply) and demonstrate its importance for adult muscle development and integrity, reproduction and larval viability. Sply expression is temporally regulated, with onset of expression during mid-embryogenesis. Sply null mutants accumulate both phosphorylated and unphosphorylated sphingoid bases and exhibit semi-lethality, increased apoptosis in developing embryos, diminished egg-laying, and gross pattern abnormalities in dorsal longitudinal flight muscles. These defects are corrected by restoring Sply expression or by introduction of a suppressor mutation that diminishes sphingolipid synthesis and accumulation of sphingolipid intermediates. This is the first demonstration of novel and complex developmental pathologies directly linked to a disruption of sphingolipid catabolism in metazoans.     

Antioxidant associated chemoprevention by selenomethionine in murine tumor model

Effectiveness of selenium in different forms like sodium selenite, selenocysteine and selenomethionine has been compared in four different doses, namely 4, 6, 8 and 10 ppm of each, in terms of their bioavailability and prolongation of survival of Dalton's lymphorna (DL) bearing mice. Selenomethionine, at a dose of 8 ppm, was found to be the most bioavailable and least cytotoxic form that was capable of increasing the life span of the tumour bearing hosts maximally (almost two-fold). Benef iciality of selenomethionine has also been studied by observing continuous changes brought about by this compound on the glutathione (GSH) level, glutathione peroxidase (GPx) activity and extent of lipid peroxidation in the hepatic tissue of the tumour bearing hosts, which are indispensable for a cell to function normally and are found to exhibit significantly altered behaviour in neoplastic cells. Selenomethionine caused the maintenance of high steady state GSH level and a normal GPx activity during the fist phase of tumour growth. It also controlled lipid peroxidation during the first 15-20 days following tumour transplantation. These conditions helped in the maintenance of intracellular redox balance, cellular integrity and metabolic rhythms of cells in DL bearing mice receiving selenomethionine.Affiliation     

Recognition of 5-aminouracil (U(#)) in the central strand of a DNA triplex: orientation selective binding of different third strand bases

A necessary feature of the natural base triads for triplex formation is the requirement of a purine (A or G) in the central position, since only these provide sets of two hydrogen bond donors/acceptors in the major groove of the double helix. Pyrimidine bases devoid of this feature have incompatible complementarity and lead to triplexes with lower stability. This paper demonstrates that 5-aminouracil (U^#) (I), a pyrimidine nucleobase analogue of T in which 5-methyl is replaced by 5-amino group, with hydrogen bonding sites on both sides, is compatible in the central position of triplex triad X*U^#·A, where X = A/G/C/T/2-aminopurine (AP), and * and · represent Hoogsteen and Watson–Crick hydrogen bonding patterns respectively. A novel recognition selectivity based on the orientation (parallel/antiparallel) of the third strand purines A, G or AP with A in the parallel motif (A_p*U^#·A), and G/AP in the antiparallel motif (G_ap/AP_ap*U^#·A) is observed. Similarly for pyrimidines in the third strand, C is accepted only in a parallel mode (C_p*U^#·A). Significantly, T is recognised in both parallel and antiparallel modes (T_p/T_ap*U^#·A), with the antiparallel mode being stable compared to the parallel one. The ‘U^#’ triplexes are also more stable than the corresponding control ‘T’ triplexes. The results expand the lexicon of triplex triads with a recognition motif consisting of pyrimidine in the central strand.