Transient Superdiffusion and Long-Range Correlations in the Motility Patterns of Trypanosomatid Flagellate Protozoa

<div><p>We report on a diffusive analysis of the motion of flagellate protozoa species. These parasites are the etiological agents of neglected tropical diseases: leishmaniasis caused by <i>Leishmania amazonensis</i> and <i>Leishmania braziliensis</i>, African sleeping sickness caused by <i>Trypanosoma brucei</i>, and Chagas disease caused by <i>Trypanosoma cruzi</i>. By tracking the positions of these parasites and evaluating the variance related to the radial positions, we find that their motions are characterized by a short-time transient superdiffusive behavior. Also, the probability distributions of the radial positions are self-similar and can be approximated by a stretched Gaussian distribution. We further investigate the probability distributions of the radial velocities of individual trajectories. Among several candidates, we find that the generalized gamma distribution shows a good agreement with these distributions. The velocity time series have long-range correlations, displaying a strong persistent behavior (Hurst exponents close to one). The prevalence of “universal” patterns across all analyzed species indicates that similar mechanisms may be ruling the motion of these parasites, despite their differences in morphological traits. In addition, further analysis of these patterns could become a useful tool for investigating the activity of new candidate drugs against these and others neglected tropical diseases.</p></div

Dataset summary.

<p>Dataset summary.</p

Illustration of trajectories and velocities.

<p>A) Typical swimming trajectories of the <i>L. amazonensis</i> and B) the corresponding time series of the radial velocities <i>v</i>(<i>t</i>) are shown. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0152092#pone.0152092.s002" target="_blank">S1 Fig</a> for other protozoa. C) Average velocities and D) standard deviation over all trajectories for each protozoan are represented in the bar plots. The error bars are 95% confidence intervals calculated via bootstrapping.</p

Synthesis, mechanism elucidation and biological insights of tellurium(IV)-containing heterocycles

Inspired by the synthetic and biological potential of organotellurium substances, a series of five- and six-membered ring organotelluranes containing a Te−O bond were synthesized and characterized. Theoretical calculations elucidated the mechanism for the oxidation-cyclization processes involved in the formation of the heterocycles, consistent with chlorine transfer to hydroxy telluride, followed by a cyclization step with simultaneous formation of the new Te−O bond and deprotonation of the OH group. Moreover, theoretical calculations also indicated anti-diastereoisomers to be major products for two chirality center–containing compounds. Antileishmanial assays against Leishmania amazonensis promastigotes disclosed 1,2λ 4-oxatellurane LQ50 (IC 50=4.1±1.0; SI=12), 1,2λ 4-oxatellurolane LQ04 (IC 50=7.0±1.3; SI=7) and 1,2λ 4-benzoxatellurole LQ56 (IC 50=5.7±0.3; SI=6) as more powerful and more selective compounds than the reference, being up to four times more active. A stability study supported by 125Te NMR analyses showed that these heterocycles do not suffer structural modifications in aqueous-organic media or at temperatures up to 65 °C

CHEMICAL STUDY AND ANTIPROLIFERATIVE, TRYPANOCIDAL AND LEISHMANICIDAL ACTIVITIES OF Maxillaria picta

The chemical study of the orchid Maxillaria picta resulted in the isolation of the bioactive stilbenes phoyunbene B and phoyunbene C, in addition to four phenolic acids, one xanthone, steroidal compounds and two triterpenes. Crude extract, fractions, subfractions and the isolated xanthone were evaluated for anticancer activity against human tumor cell lines and against evolutionary forms of T. cruzi and L. amazonensis. The structures of the compounds were determined by GC-MS, and ¹H NMR, 13C NMR spectral methods as well as bidimensional techniques