3,036 research outputs found
Extracellular ATP triggers proteolysis and cytosolic Ca²⁺ rise in Plasmodium berghei and Plasmodium yoelii malaria parasites.
BACKGROUND: Plasmodium has a complex cell biology and it is essential to dissect the cell-signalling pathways underlying its survival within the host. METHODS: Using the fluorescence resonance energy transfer (FRET) peptide substrate Abz-AIKFFARQ-EDDnp and Fluo4/AM, the effects of extracellular ATP on triggering proteolysis and Ca²⁺ signalling in Plasmodium berghei and Plasmodium yoelii malaria parasites were investigated. RESULTS: The protease activity was blocked in the presence of the purinergic receptor blockers suramin (50 μM) and PPADS (50 μM) or the extracellular and intracellular calcium chelators EGTA (5 mM) and BAPTA/AM (25, 100, 200 and 500 μM), respectively for P. yoelii and P. berghei. Addition of ATP (50, 70, 200 and 250 μM) to isolated parasites previously loaded with Fluo4/AM in a Ca²⁺-containing medium led to an increase in cytosolic calcium. This rise was blocked by pre-incubating the parasites with either purinergic antagonists PPADS (50 μM), TNP-ATP (50 μM) or the purinergic blockers KN-62 (10 μM) and Ip5I (10 μM). Incubating P. berghei infected cells with KN-62 (200 μM) resulted in a changed profile of merozoite surface protein 1 (MSP1) processing as revealed by western blot assays. Moreover incubating P. berghei for 17 h with KN-62 (10 μM) led to an increase in rings forms (82% ± 4, n = 11) and a decrease in trophozoite forms (18% ± 4, n = 11). CONCLUSIONS: The data clearly show that purinergic signalling modulates P. berghei protease(s) activity and that MSP1 is one target in this pathway
Rent Seeking and the Unveiling of 'De Facto' Institutions: Development and Colonial Heritage within Brazil
This paper analyzes the roots of variation in de facto institutions, within a constant de jure institutional setting. We explore the role of rent-seeking episodes in colonial Brazil as determinants of the quality of current local institutions, and argue that this variation reveals a de facto dimension of institutional quality. We show that municipalities with origins tracing back to the sugar-cane colonial cycle -- characterized by a polarized and oligarchic socioeconomic structure -- display today more inequality in the distribution of land. Municipalities with origins tracing back to the gold colonial cycle -- characterized by an over-bureaucratic and heavily intervening presence of the Portuguese state -- display today worse governance practices and less access to justice. The colonial rent-seeking episodes are also correlated with lower provision of public goods and lower income per capita today, and the latter correlation seems to work partly through worse institutional quality at the local level.
Institutional Development and Colonial Heritage within Brazil
This paper analyzes the determinants of local institutions and distribution of political power within a constant 'macro-institutional' setting. We show that characteristics of Brazilian municipalities related to institutional quality and distribution of political power are partly inherited from the colonial histories experienced by different areas of the country. Municipalities with origins tracing back to the sugar-cane colonial cycle – characterized by a polarized and oligarchic socioeconomic structure – display today more inequality in the distribution of endowments (land). Municipalities with origins tracing back to the gold colonial cycle – characterized by a heavily inefficient presence of the Portuguese state – display today worse governance practices and less access to justice. The colonial rent-seeking episodes are also correlated with lower provision of public goods and lower income per capita.institutions, colonial heritage, rent-seeking, geography, Brazil
F as in Fat: How Obesity Policies Are Failing in America, 2005
Examines national and state obesity rates and government policies. Challenges the research community to focus on major research questions to inform policy decisions, and policymakers to pursue actions to combat the obesity crisis
Direct and trans-generational effects of male and female gut microbiota in Drosophila melanogaster
Funding This study was supported by the National Council for Scientific and Technological Development (CNPq). Acknowledgement We acknowledge Stuart Wigby, Adam Wong and Phil Taylor for discussion and support during the experiment.Peer reviewedPublisher PD
SeekDeep: single-base resolution de novo clustering for amplicon deep sequencing
PCR amplicon deep sequencing continues to transform the investigation of genetic diversity in viral, bacterial, and eukaryotic populations. In eukaryotic populations such as Plasmodium falciparum infections, it is important to discriminate sequences differing by a single nucleotide polymorphism. In bacterial populations, single-base resolution can provide improved resolution towards species and strains. Here, we introduce the SeekDeep suite built around the qluster algorithm, which is capable of accurately building de novo clusters representing true, biological local haplotypes differing by just a single base. It outperforms current software, particularly at low frequencies and at low input read depths, whether resolving single-base differences or traditional OTUs. SeekDeep is open source and works with all major sequencing technologies, making it broadly useful in a wide variety of applications of amplicon deep sequencing to extract accurate and maximal biologic information
Activation of minority-variant Plasmodium vivax hypnozoites following artesunate + amodiaquine treatment in a 23-year old man with relapsing malaria in Antananarivo, Madagascar
In endemic areas, Plasmodium vivax relapses are difficult to distinguish from new infections. Genotyping of patients who experience relapse after returning to a malaria-free area can be used to explore the nature of hypnozoite activation and relapse. This paper describes a person who developed P. vivax malaria for the first time after travelling to Boriziny in the malaria endemic coastal area of Madagascar, then suffered two P. vivax relapses 11 weeks and 21 weeks later despite remaining in Antananarivo in the malaria-free central highlands area. He was treated with the combination artesunate + amodiaquine according to the national malaria policy in Madagascar. Genotyping by PCR-RFLP at pvmsp-3α as well as pvmsp1 heteroduplex tracking assay (HTA) showed the same dominant genotype at each relapse. Multiple recurring minority variants were also detected at each relapse, highlighting the propensity for multiple hypnozoite clones to activate simultaneously to cause relapse
The L\'evy Map: A two-dimensional nonlinear map characterized by tunable L\'evy flights
Once recognizing that point particles moving inside the extended version of
the rippled billiard perform L\'evy flights characterized by a L\'evy-type
distribution with , we derive a
generalized two-dimensional non-linear map able to produce L\'evy
flights described by with . Due to this property, we name
as the L\'evy Map. Then, by applying Chirikov's overlapping
resonance criteria we are able to identify the onset of global chaos as a
function of the parameters of the map. With this, we state the conditions under
which the L\'evy Map could be used as a L\'evy pseudo-random number generator
and, furthermore, confirm its applicability by computing scattering properties
of disordered wires.Comment: 6 pages, 5 figure
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