A Surface-Induced Asymmetric Program Promotes Tissue Colonization by Pseudomonas aeruginosa

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PHOTOBIOTREATMENT: INFLUENCE OF NITROGEN AND PHOSPHORUS RATIO IN WASTEWATER ON GROWTH KINETICS OF SCENEDESMUS OBLIQUUS

Nitrogen and phosphorus concentration in the effluent of a wastewater treatment plant can vary significantly, which could affect the growth kinetic and chemical composition of microalgae when cultivated in this medium. The aim of this work was to study the rate of growth, nutrient removal and carbon dioxide biofixation as well as biomass composition of Scenedesmus obliquus (S. obliquus) when it is cultivated in wastewater at different nitrogen and phosphorus ratio, from 1:1 to 35:1. A more homogeneous method for calculating productivities in batch reactors was proposed. The proper N:P ratio for achieving optimum batch biomass productivity ranged between 9 and 13 (263 and 322 mg L^?1 d^?1 respectively). This was also the ratio range for achieving a total N and P removal. Above and below this range (9–13) the maximum biomass concentration changed, instead of the specific growth rate.The maximum carbon dioxide biofixation rate was achieved at N:P ratio between 13 and 22 (553 and 557 mg CO2 L^?1 d^?1 respectively). Lipid and crude protein content, both depend on the aging culture, reaching the maximum lipid content (34%) at the lowest N:P (1:1) and the maximum crude protein content (34.2%) at the highest N:P (35:1).     

Digestive and metabolic flexibility allows female degus to cope with lactation costs

Lactation is the most energetically demanding period in the life cycle of female mammals, and its effects on digestive flexibility and the size of internal organs have been extensively studied in laboratory mice and rats since the early 1900s. However, there have been only two studies on this topic for wild rodent species. Here, we analyzed digestive flexibility--that is, changes in gut content, activity of digestive enzymes, and gut morphology--during lactation in the caviomorph rodent Octodon degus. In addition, we evaluated changes in the size of other internal organs and analyzed their relationship with the resting metabolic rate. We found that gut content, the dry masses of digestive chambers, the dry mass of liver, and resting metabolic rate were greater in lactating than in nonbreeding control females. In contrast, fat stores were higher in control subjects. Maltase and aminopeptidase-N specific activity did not change with lactation, and both enzymes had greater activity values in the middle portion of the small intestine. Thus, our data indicate that the previously reported increase in food assimilation that occurs during lactation in O. degus is related to a mass increase in several central organs, leading, in turn, to higher energetic costs. Fat stores may help to mitigate these costs, but, as expected for small animals, to a limited extent. Our study reveals a complex interplay among energy acquisition, storage, and expenditure processes that ultimately determine an organism's fitness.     

The incorporation of deoxyuridine monophosphate into DNA increases the sister-chromatid exchange yield

The effect of a treatment with 5-fluoro-2'-deoxyuridine (FdUrd) in combination with 2'-deoxyuridine (dUrd) on cell proliferation, incorporation of DNA precursors into DNA and sister-chromatid exchanges (SCEs) has been analyzed in Allium cepa meristem cells. FdUrd in the range 10(-9)-5 X 10(-7) M produced a dose- and time-dependent decrease in the amount of cells in mitosis. This inhibitory effect could be reversed by 70-80% in short-term (6 h) experiments, by exogenously supplied dUrd at a concentration of 10(-4) M. However, at the highest FdUrd dose tested (10(-7) M), 10(-4) M dUrd could not reverse the FdUrd effect in long-term experiments (20 h, about one cell cycle interval), as shown by analyzing the kinetics of synchronous cell populations. DNA extracted from cells pulsed with [6-3H]dUrd in the presence of FdUrd and 6-amino-uracil (6-AU), an inhibitor of uracil-DNA glycosylase, contained a small amount of label (at least 3% of the total radioactivity incorporated into DNA) in the form of [6-3H]dUMP. Thus, we conclude that, under our experimental conditions, exogenously supplied dUrd may be metabolized intracellularly to 2'-deoxyuridine triphosphate (dUTP) and that this deoxynucleotide may eventually be mis-incorporated into DNA. As far as the formation of SCEs is concerned, analysis of second division chromosomes showed that 2'-deoxyuridine monophosphate (dUMP) residues present in newly-synthesized DNA strands are probably not relevant to SCE formation. However, by analyzing SCE levels in third division chromosomes of cells treated with FdUrd and dUrd during their second cycle, we have scored a 6-fold increase in the reciprocal SCE level which demonstrates that the replication of a dUMP-containing DNA template leads to a higher SCE yield.     

Phospholipase D1 downregulation by α-synuclein: Implications for neurodegeneration in Parkinson's disease

We have previously shown that phospholipase D (PLD) pathways have a role in neuronal degeneration; in particular, we found that PLD activation is associated with synaptic injury induced by oxidative stress. In the present study, we investigated the effect of α-synuclein (α-syn) overexpression on PLD signaling. Wild Type (WT) α-syn was found to trigger the inhibition of PLD1 expression as well as a decrease in ERK1/2 phosphorylation and expression levels. Moreover, ERK1/2 subcellular localization was shown to be modulated by WT α-syn in a PLD1-dependent manner. Indeed, PLD1 inhibition was found to alter the neurofilament network and F-actin distribution regardless of the presence of WT α-syn. In line with this, neuroblastoma cells expressing WT α-syn exhibited a degenerative-like phenotype characterized by a marked reduction in neurofilament light subunit (NFL) expression and the rearrangement of the F-actin organization, compared with either the untransfected or the empty vector-transfected cells. The gain of function of PLD1 through the overexpression of its active form had the effect of restoring NFL expression in WT α-syn neurons. Taken together, our findings reveal an unforeseen role for α-syn in PLD regulation: PLD1 downregulation may constitute an early mechanism in the initial stages of WT α-syn-triggered neurodegeneration.     

Representation of Ecosystem Services by Terrestrial Protected Areas: Chile as a Case Study

Protected areas are increasingly considered to play a key role in the global maintenance of ecosystem processes and the ecosystem services they provide. It is thus vital to assess the extent to which existing protected area systems represent those services. Here, for the first time, we document the effectiveness of the current Chilean protected area system and its planned extensions in representing both ecosystem services (plant productivity, carbon storage and agricultural production) and biodiversity. Additionally, we evaluate the effectiveness of protected areas based on their respective management objectives. Our results show that existing protected areas in Chile do not contain an unusually high proportion of carbon storage (14.9%), agricultural production (0.2%) or biodiversity (11.8%), and also represent a low level of plant productivity (Normalized Difference Vegetation Index of 0.38). Proposed additional priority sites enhance the representation of ecosystem services and biodiversity, but not sufficiently to attain levels of representation higher than would be expected for their area of coverage. Moreover, when the species groups were assessed separately, amphibians was the only one well represented. Suggested priority sites for biodiversity conservation, without formal protection yet, was the only protected area category that over-represents carbon storage, agricultural production and biodiversity. The low representation of ecosystem services and species’ distribution ranges by the current protected area system is because these protected areas are heavily biased toward southern Chile, and contain large extents of ice and bare rock. The designation and management of proposed priority sites needs to be addressed in order to increase the representation of ecosystem services within the Chilean protected area system.     

Neurogenic differentiation of human adipose-derived stem cells: Relevance of different signaling molecules,transcription factors,and key marker genes

Since numerous diseases affect the central nervous system and it has limited self-repair capability, a great interest in using stem cells as an alternative cell source is generated. Previous reports have shown the differentiation of adipose-derived stem cells in neuron-like cells and it has also been proved that the expression pattern of patterning, proneural, and neural factors, such as Pax6, Mash1, Ngn2, NeuroD1, Tbr2 and Tbr1, regulates and defines adult neurogenesis. Regarding this, we hypothesize that a functional parallelism between adult neurogenesis and neuronal differentiation of human adipose-derived stem cells exists. In this study we differentiate human adipose-derived stem cells into neuron-like cells and analyze the expression pattern of different patterning, proneural, neural and neurotransmitter genes, before and after neuronal differentiation. The neuron-like cells expressed neuronal markers, patterning and proneural factors characteristics of intermediate stages of neuronal differentiation. Thus we demonstrated that it is possible to differentiate adipose-derived stem cells in vitro into immature neuron-like cells and that this process is regulated in a similar way to adult neurogenesis. This may contribute to elucidate molecular mechanisms involved in neuronal differentiation of adult human non-neural cells, in aid of the development of potential therapeutic tools for diseases of the nervous system.