The host Rab9a/Rab32 axis is actively recruited to the Trypanosoma cruzi parasitophorous vacuole and benefits the infection cycle.

Trypanosoma cruzi, the etiological agent of Chagas disease is a protozoan parasite that infects phagocytic and non-phagocytic mammalian cells. At early stages of infection, trypomastigotes, the infective forms of this parasite, localize in a vesicular compartment called the T. cruzi parasitophorous vacuole until the exit of parasites to the host cell cytoplasm where continue their infective cycle. Rab proteins participate in the membrane traffic's molecular machinery, functioning as central regulators of vesicle recognition and transport. In previous work, we demonstrated that endocytic Rabs are key factors of the T. cruzi infection process in non-phagocytic cells, regulating the formation and the maturation of the vacuole. In this work, we identified and characterized other molecular components of the vesicular transport pathways and their participation in the T. cruzi infection. We found that Rab9a and Rab32, two regulators of the endocytic and autophagic pathways, were actively recruited to the T. cruzi vacuoles and favored the late stages of the infective process. The recruitment was specific and dependent on T. cruzi protein synthesis. Interestingly, Rab32 association depends on the presence of Rab9a in the vacuolar membrane, while the inhibition of the cysteine-protease cruzipain, a T. cruzi virulence factor, significantly decreases both Rab9a and Rab32 association with the vacuole. In summary, this work showed for the first time that specific molecules produced and secreted by the parasite can subvert intracellular components of host cells to benefit the infection. These new data shed light on the complex map of interactions between T. cruzi and the host cell and introduce concepts that can be useful in finding new forms of intervention against this parasite in the future.

Deep intrinsic decomposition trained on surreal scenes yet with realistic light effects.

Estimation of intrinsic images still remains a challenging task due to weaknesses of ground-truth datasets, which either are too small or present non-realistic issues. On the other hand, end-to-end deep learning architectures start to achieve interesting results that we believe could be improved if important physical hints were not ignored. In this work, we present a twofold framework: (a) a flexible generation of images overcoming some classical dataset problems such as larger size jointly with coherent lighting appearance; and (b) a flexible architecture tying physical properties through intrinsic losses. Our proposal is versatile, presents low computation time, and achieves state-of-the-art results.

Soluble N-ethylmaleimide-sensitive factor attachment protein receptors required during Trypanosoma cruzi parasitophorous vacuole development.

Trypanosoma cruzi, the etiologic agent of Chagas disease, is an obligate intracellular parasite that exploits different host vesicular pathways to invade the target cells. Vesicular and target soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are key proteins of the intracellular membrane fusion machinery. During the early times of T. cruzi infection, several vesicles are attracted to the parasite contact sites in the plasma membrane. Fusion of these vesicles promotes the formation of the parasitic vacuole and parasite entry. In this work, we study the requirement and the nature of SNAREs involved in the fusion events that take place during T. cruzi infection. Our results show that inhibition of N-ethylmaleimide-sensitive factor protein, a protein required for SNARE complex disassembly, impairs T. cruzi infection. Both TI-VAMP/VAMP7 and cellubrevin/VAMP3, two v-SNAREs of the endocytic and exocytic pathways, are specifically recruited to the parasitophorous vacuole membrane in a synchronized manner but, although VAMP3 is acquired earlier than VAMP7, impairment of VAMP3 by tetanus neurotoxin fails to reduce T. cruzi infection. In contrast, reduction of VAMP7 activity by expression of VAMP7's longin domain, depletion by small interfering RNA or knockout, significantly decreases T. cruzi infection susceptibility as a result of a minor acquisition of lysosomal components to the parasitic vacuole. In addition, overexpression of the VAMP7 partner Vti1b increases the infection, whereas expression of a KIF5 kinesin mutant reduces VAMP7 recruitment to vacuole and, concomitantly, T. cruzi infection. Altogether, these data support a key role of TI-VAMP/VAMP7 in the fusion events that culminate in the T. cruzi parasitophorous vacuole development.

Enhancing spatio-chromatic representation with more-than-three color coding for image description.

The extraction of spatio-chromatic features from color images is usually performed independently on each color channel. Usual 3D color spaces, such as RGB, present a high inter-channel correlation for natural images. This correlation can be reduced using color-opponent representations, but the spatial structure of regions with small color differences is not fully captured in two generic Red-Green and Blue-Yellow channels. To overcome these problems, we propose new color coding that is adapted to the specific content of each image. Our proposal is based on two steps: (a) setting the number of channels to the number of distinctive colors we find in each image (avoiding the problem of channel correlation), and (b) building a channel representation that maximizes contrast differences within each color channel (avoiding the problem of low local contrast). We call this approach more-than-three color coding (MTT) to emphasize the fact that the number of channels is adapted to the image content. The higher the color complexity of an image, the more channels can be used to represent it. Here we select distinctive colors as the most predominant in the image, which we call color pivots, and we build the new color coding strategy using these color pivots as a basis. To evaluate the proposed approach, we measure the efficiency in an image categorization task. We show how a generic descriptor improves performance at the description level when applied to the MTT coding.

Experimental Evidence for the Role of Intonation in Evidential Marking.

This paper investigates the role of intonation in the marking of directly-perceived information in Majorcan Catalan polar questions. We conducted a perception experiment in which a total of 72 participants were introduced to a set of twins who were exposed to different types of evidence for a given p(roposition). One twin inferred p based on direct sensory information (via one of the five senses), while the other had been told that p by a third party, that is, reported information. Participants listened to a set of discourse contexts that ended in critical stimuli with three attested combinations of particle/intonation in this variety of Catalan: (1) polar questions produced with a falling nuclear contour ¡H+L* L%; (2) polar questions headed with the particle que 'that' produced with ¡H+L* L%; and (3) polar questions headed with the particle que and produced with a rise-fall L+H* L%. After hearing the stimulus, participants had to decide which of the twins had uttered the question-the one who inferred a proposition ( p) based on direct sensory information or the one who had been told p by a third party. The results show that listeners very consistently associate the que + L+H* L% combination with inferences drawn from direct sensory evidence as opposed to reported evidence. This shows that particles may work in tandem with intonation to convey the information source. Importantly, we show that intonation is a part of grammar that may be recruited for evidential strategies.

Ecological correlates of population genetics in Linum suffruticosum, an heterostylous polyploid and taxonomic complex endemic to the Western Mediterranean Basin.

Linum suffruticosum s.l. is a taxonomic complex widespread in the Western Mediterranean basin. The complex is characterized by a high phenotypic and cytogenetic diversity, and by a unique three-dimensional heterostyly system that makes it an obligate outcrosser. We studied the patterns of genetic diversity and structure of populations throughout the entire distribution of L. suffruticosum s.l. with microsatellite markers. We analysed their relationships with various biological and ecological variables, including the morph ratio and sex organ reciprocity of populations measured with a novel multi-dimensional method. Populations consistently showed an approximate 1:1 morph ratio with high sex organ reciprocity and high genetic diversity. We found high genetic differentiation of populations, showing a pattern of isolation by distance. The Rif mountains in NW Africa were the most important genetic barrier. The taxonomic treatment within the group was not related to the genetic differentiation of populations, but to their environmental differentiation. Genetic diversity was unrelated to latitude, elevation, population size, niche suitability or breeding system. However, there was a clear influence of ploidy level on the genetic diversity of populations, and a seeming centre-periphery pattern in its distribution. Our results suggest that polyploidization events, high outcrossing rates, isolation by distance and important geographical barriers to gene flow have played major roles in the microevolutionary history of this species complex.

Chromatic settings and the structural color constancy index.

Color constancy is usually measured by achromatic setting, asymmetric matching, or color naming paradigms, whose results are interpreted in terms of indexes and models that arguably do not capture the full complexity of the phenomenon. Here we propose a new paradigm, chromatic setting, which allows a more comprehensive characterization of color constancy through the measurement of multiple points in color space under immersive adaptation. We demonstrated its feasibility by assessing the consistency of subjects' responses over time. The paradigm was applied to two-dimensional (2-D) Mondrian stimuli under three different illuminants, and the results were used to fit a set of linear color constancy models. The use of multiple colors improved the precision of more complex linear models compared to the popular diagonal model computed from gray. Our results show that a diagonal plus translation matrix that models mechanisms other than cone gain might be best suited to explain the phenomenon. Additionally, we calculated a number of color constancy indices for several points in color space, and our results suggest that interrelations among colors are not as uniform as previously believed. To account for this variability, we developed a new structural color constancy index that takes into account the magnitude and orientation of the chromatic shift in addition to the interrelations among colors and memory effects.

Intonation as an encoder of speaker certainty: information and confirmation yes-no questions in Catalan.

Recent studies in the field of intonational phonology have shown that information-seeking questions can be distinguished from confirmation-seeking questions by prosodic means in a variety of languages (Armstrong, 2010, for Puerto Rican Spanish; Grice & Savino, 1997, for Bari Italian; Kügler, 2003, for Leipzig German; Mata & Santos, 2010, for European Portuguese; Vanrell, Mascaró, Prieto, & Torres-Tamarit, 2010, for Catalan). However, all these studies have relied on production experiments and little is known about the perceptual relevance of these intonational cues. This paper explores whether Majorcan Catalan listeners distinguish information- and confirmation-seeking questions by means of two distinct nuclear falling pitch accents. Three behavioral tasks were conducted with 20 Majorcan Catalan subjects, namely a semantic congruity test, a rating test, and a classical categorical perception identification/discrimination test. The results show that a difference in pitch scaling on the leading H tone of the H+L* nuclear pitch accent is the main cue used by Majorcan Catalan listeners to distinguish confirmation questions from information-seeking questions. Thus, while a iH+L* pitch accent signals an information-seeking question (i.e., the speaker has no expectation about the nature of the answer), the H+L* pitch accent indicates that the speaker is asking about mutually shared information. We argue that these results have implications in representing the distinctions of tonal height in Catalan. The results also support the claim that phonological contrasts in intonation, together with other linguistic strategies, can signal the speakers' beliefs about the certainty of the proposition expressed.

Tonal targets in early child English, Spanish, and Catalan.

This study analyses the scaling and alignment of low and high intonational targets in the speech of 27 children - nine English-speaking, nine Catalan-speaking and nine Spanish-speaking - between the ages of two and six years. We compared the intonational patterns of words controlled for number of syllables and stress position in the child speech to the adult target speech provided by their mothers, and to a dataset of adult-directed speech recorded at a later stage for the purpose of measuring pitch height. A corpus of 624 utterances was elicited using a controlled naming task and analysed within the Autosegmental Metrical framework. Measuring the pitch height and pitch timing of nuclear pitch accents, we found that once the effects of syllable duration are accounted for, young children reach tonal targets with remarkable precision. Overall, the results indicate that the phonetic aspects of intonation are acquired from a very early age. Even the youngest children show adult-like alignment of the low target, although mastery of the high target increases with age. Young Spanish-speaking children, however, show a more precise attainment of pitch scaling and alignment of their (high) tonal targets than do Catalan and English children; where the ambient language lies within a general prosodic typology appears to influence the acquisition of tonal targets.

Comparative analysis of humoral immune response upon the three first vaccines applied in Argentina: IgG production and neutralizing capacity against SARS-CoV-2.

The population that has not received a SARS-CoV-2 vaccine is at high risk for infection whereas vaccination prevents COVID-19 severe disease, hospitalization, and death. In Argentina, to date, more than 50 million doses of vaccines against SARS-CoV-2 have been administered. The three main vaccines applied are Sputnik V, Oxford-AstraZeneca, and Sinopharm. In this study, we have compared the antibody response of voluntary individuals at day 0 (first dose vaccination day) and at 21-25 days post first and second dose. Our results indicate that at 21-25 days after the administration of the first doses of Sputnik V the large majority of the people vaccinated 80% (n = 15) presented high humoral responses as determined by the measurement of IgG against the Spike protein and the Receptor Binding Domain (RBD). In the case of those vaccinated with AstraZeneca, the percentage was 80% (n = 15) whereas this value was reduced to only 25% (n = 16) in persons that received Sinopharm. However, after the second doses, most of the recipients had significant levels of antibodies. The virus neutralizing capacity of the antibodies generated was evaluated using a pseudotyped VSV-SARS-CoV2 Spike expressing eGFP and the data was analyzed by fluorescence microscopy and flow cytometry. The results indicate that a good correlation exists between the levels of IgG and the neutralizing capacity of the antibodies against the recombinant virus. Our results stand out the importance of applying the second dose of Sinopharm. Thus, the present report provides data that will contribute to decisions making about the vaccine implementation plans of action for, not only our region but our country to support the fight against the COVID-19 global pandemic.

Autophagy in protists and their hosts: When, how and why?

Pathogenic protists are a group of organisms responsible for causing a variety of human diseases including malaria, sleeping sickness, Chagas disease, leishmaniasis, and toxoplasmosis, among others. These diseases, which affect more than one billion people globally, mainly the poorest populations, are characterized by severe chronic stages and the lack of effective antiparasitic treatment. Parasitic protists display complex life-cycles and go through different cellular transformations in order to adapt to the different hosts they live in. Autophagy, a highly conserved cellular degradation process, has emerged as a key mechanism required for these differentiation processes, as well as other functions that are crucial to parasite fitness. In contrast to yeasts and mammals, protist autophagy is characterized by a modest number of conserved autophagy-related proteins (ATGs) that, even though, can drive the autophagosome formation and degradation. In addition, during their intracellular cycle, the interaction of these pathogens with the host autophagy system plays a crucial role resulting in a beneficial or harmful effect that is important for the outcome of the infection. In this review, we summarize the current state of knowledge on autophagy and other related mechanisms in pathogenic protists and their hosts. We sought to emphasize when, how, and why this process takes place, and the effects it may have on the parasitic cycle. A better understanding of the significance of autophagy for the protist life-cycle will potentially be helpful to design novel anti-parasitic strategies.

Molecular and cellular mechanisms involved in the Trypanosoma cruzi/host cell interplay.

The protozoan parasite Trypanosoma cruzi has a complex biological cycle that involves vertebrate and invertebrate hosts. In mammals, the infective trypomastigote form of this parasite can invade several cell types by exploiting phagocytic-like or nonphagocytic mechanisms depending on the class of cell involved. Morphological studies showed that when trypomastigotes contact macrophages, they induce the formation of plasma membrane protrusions that differ from the canonical phagocytosis that occurs in the case of noninfective epimastigotes. In contrast, when trypomastigotes infect epithelial or muscle cells, the cell surface is minimally modified, suggesting the induction of a different class of process. Lysosomal-dependent or -independent T. cruzi invasion of host cells are two different models that describe the molecular and cellular events activated during parasite entry into nonphagocytic cells. In this context, we have previously shown that induction of autophagy in host cells before infection favors T. cruzi invasion. Furthermore, we demonstrate that autophagosomes and the autophagosomal protein LC3 are recruited to the T. cruzi entry sites and that the newly formed T. cruzi parasitophorous vacuole has characteristics of an autophagolysosome. This review summarizes the current knowledge of the molecular and cellular mechanisms of T. cruzi invasion in nonphagocytic cells. Based on our findings, we propose a new model in which T. cruzi takes advantage of the upregulation of autophagy during starvation to increase its successful colonization of host cells.

Spectral sharpening by spherical sampling.

There are many works in color that assume illumination change can be modeled by multiplying sensor responses by individual scaling factors. The early research in this area is sometimes grouped under the heading "von Kries adaptation": the scaling factors are applied to the cone responses. In more recent studies, both in psychophysics and in computational analysis, it has been proposed that scaling factors should be applied to linear combinations of the cones that have narrower support: they should be applied to the so-called "sharp sensors." In this paper, we generalize the computational approach to spectral sharpening in three important ways. First, we introduce spherical sampling as a tool that allows us to enumerate in a principled way all linear combinations of the cones. This allows us to, second, find the optimal sharp sensors that minimize a variety of error measures including CIE Delta E (previous work on spectral sharpening minimized RMS) and color ratio stability. Lastly, we extend the spherical sampling paradigm to the multispectral case. Here the objective is to model the interaction of light and surface in terms of color signal spectra. Spherical sampling is shown to improve on the state of the art.

A new spectrally sharpened sensor basis to predict color naming, unique hues, and hue cancellation.

When light is reflected off a surface, there is a linear relation between the three human photoreceptor responses to the incoming light and the three photoreceptor responses to the reflected light. Different colored surfaces have different linear relations. Recently, Philipona and O'Regan (2006) showed that when this relation is singular in a mathematical sense, then the surface is perceived as having a highly nameable color. Furthermore, white light reflected by that surface is perceived as corresponding precisely to one of the four psychophysically measured unique hues. However, Philipona and O'Regan's approach seems unrelated to classical psychophysical models of color constancy. In this paper we make this link. We begin by transforming cone sensors to spectrally sharpened counterparts. In sharp color space, illumination change can be modeled by simple von Kries type scalings of response values within each of the spectrally sharpened response channels. In this space, Philipona and O'Regan's linear relation is captured by a simple Land-type color designator defined by dividing reflected light by incident light. This link between Philipona and O'Regan's theory and Land's notion of color designator gives the model biological plausibility. We then show that Philipona and O'Regan's singular surfaces are surfaces which are very close to activating only one or only two of such newly defined spectrally sharpened sensors, instead of the usual three. Closeness to zero is quantified in a new simplified measure of singularity which is also shown to relate to the chromaticness of colors. As in Philipona and O'Regan's original work, our new theory accounts for a large variety of psychophysical color data.

Is prosodic development correlated with grammatical and lexical development? Evidence from emerging intonation in Catalan and Spanish.

This investigation focuses on the development of intonation patterns in four Catalan-speaking children and two Spanish-speaking children between 0 ; 11 and 2 ; 4. Pitch contours were prosodically analyzed within the Autosegmental Metrical framework in all meaningful utterances, for a total of 6558 utterances. The pragmatic meaning and communicative function were also assessed. Three main conclusions arise from the results. First, the study shows that the Autosegmental Metrical model can be successfully used to transcribe early intonation contours. Second, results reveal that children's emerging intonation is largely independent of grammatical development, and generally it develops well before the appearance of two-word combinations. As for the relationship between lexical and intonational development, the data show that the emergence of intonational grammar is related to the onset of speech and the presence of a small lexicon. Finally, we discuss the implications of these results for the biological hypothesis of intonational production.

Measuring child rhythm.

Interval-based rhythm metrics were applied to the speech of English, Catalan and Spanish 2, 4 and 6 year-olds, and compared with the (adult-directed) speech of their mothers. Results reveal that child speech does not fall into a well-defined rhythmic class: for all three languages, it is more 'vocalic' (higher %V) than adult speech and has a tendency towards lower variability (when normalized for speech rate) in vocalic interval duration. Consonantal interval variability, however, is higher in child speech, particularly for younger children. Nevertheless, despite the identification of common, cross-linguistic patterns in child speech, the emergence of language-specific rhythmic indices is also clearly observable, even in the speech of 2 year-olds.

Induction of Autophagy by Ursolic Acid Promotes the Elimination of Trypanosoma cruzi Amastigotes From Macrophages and Cardiac Cells.

Chagas disease, caused by the parasite Trypanosoma cruzi, is an infectious illness endemic to Latin America and still lacks an effective treatment for the chronic stage. In a previous study in our laboratory, we established the protective role of host autophagy in vivo during T. cruzi infection in mice and proposed this process as one of the mechanisms involved in the innate immune response against this parasite. In the search for an autophagy inducer that increases the anti-T. cruzi response in the host, we found ursolic acid (UA), a natural pentacyclic triterpene with many biological actions including autophagy induction. The aim of this work was to study the effect of UA on T. cruzi infection in vitro in the late infection stage, when the nests of intracellular parasites are forming, in both macrophages and cardiac cells. To test this effect, the cells were infected with T. cruzi for 24 h and then treated with UA (5-10 µM). The data showed that UA significantly decreased the number of amastigotes found in infected cells in comparison with non-treated cells. UA also induced the autophagy response in both macrophages and cardiac cells under the studied conditions, and the inhibition of this pathway during UA treatment restored the level of infection. Interestingly, LC3 protein, the main marker of autophagy, was recruited around amastigotes and the acidic probe LysoTracker localized with them, two key features of xenophagy. A direct cytotoxic effect of UA was also found on trypomastigotes of T. cruzi, whereas epimastigotes and amastigotes displayed more resistance to this drug at the studied concentrations. Taken together, these data showed that this natural compound reduces T. cruzi infection in the later stages by promoting parasite damage through the induction of autophagy. This action, in addition to the effect of this compound on trypomastigotes, points to UA as an interesting lead for Chagas disease treatment in the future.

Injectable Depot Forming Thermoresponsive Hydrogel for Sustained Intrascleral Delivery of Sunitinib Using Hollow Microneedles.

Purpose: Age-related macular degeneration is a vision-threatening disorder affecting the posterior segment of the eye. Drug delivery to the posterior segment is challenging owing to the complex anatomical and physiological structure, necessitating monthly injections of antivascular endothelial growth factors. Thermoresponsive hydrogels provide sustained drug delivery and ease of injection, due to their sol-gel transition. Poly (N-isopropyl acrylamide) (PNIPAAm) is a widely researched thermoresponsive hydrogel; however, insufficient wet strength and a wide mesh network make it inept for the entrapment of small molecules. Methods: A novel approach of grafting PNIPAAm with chitosan is exploited. A chitosan concentration altered in 10%, 30%, and 50% compared to PNIPAAm is investigated for entrapment of a small-molecular weight, hydrophilic drug, sunitinib (SUN), a multiple tyrosine kinase receptor inhibitor. Furthermore, these hydrogels were characterized using 1H-NMR, FTIR, differential scanning calorimetry (DSC), and thermogravimetric analysis for chemical characterization and viscosity, swellability, syringeability, degradation, and In-vitro permeation using Franz-diffusion cell. Results: In-vitro drug release kinetics suggested that the release of SUN could be controlled with the percentage of chitosan grafting; however, gel strength (3%-5% w/v) of 30% Cs-g-PNIPAAm did not significantly affect percentage drug release. Sustained release of SUN was observed for 1 month. In-vitro permeation studies on porcine sclera suggested that a thermoresponsive gel of chitosan grafted PNIPAAm (Cs-g-PNIPAAm) was able to sustain the drug release by 40%, compared to SUN solution. Conclusions: The study indicates that the synthesized Cs-g-NIPAAm hydrogel has the potential to serve as a tailorable injectable platform for intrascleral drug delivery applications.

Repurposing Carvedilol as a Novel Inhibitor of the Trypanosoma cruzi Autophagy Flux That Affects Parasite Replication and Survival.

T. cruzi, the causal agent of Chagas disease, is a parasite able to infect different types of host cells and to persist chronically in the tissues of human and animal hosts. These qualities and the lack of an effective treatment for the chronic stage of the disease have contributed to the durability and the spread of the disease around the world. There is an urgent necessity to find new therapies for Chagas disease. Drug repurposing is a promising and cost-saving strategy for finding new drugs for different illnesses. In this work we describe the effect of carvedilol on T. cruzi. This compound, selected by virtual screening, increased the accumulation of immature autophagosomes characterized by lower acidity and hydrolytic properties. As a consequence of this action, the survival of trypomastigotes and the replication of epimastigotes and amastigotes were impaired, resulting in a significant reduction of infection and parasite load. Furthermore, carvedilol reduced the whole-body parasite burden peak in infected mice. In summary, in this work we present a repurposed drug with a significant in vitro and in vivo activity against T. cruzi. These data in addition to other pharmacological properties make carvedilol an attractive lead for Chagas disease treatment.

Toward a unified chromatic induction model.

In a previous work (X. Otazu, M. Vanrell, & C. A. Párraga, 2008b), we showed how several brightness induction effects can be predicted using a simple multiresolution wavelet model (BIWaM). Here we present a new model for chromatic induction processes (termed Chromatic Induction Wavelet Model or CIWaM), which is also implemented on a multiresolution framework and based on similar assumptions related to the spatial frequency and the contrast surround energy of the stimulus. The CIWaM can be interpreted as a very simple extension of the BIWaM to the chromatic channels, which in our case are defined in the MacLeod-Boynton (lsY) color space. This new model allows us to unify both chromatic assimilation and chromatic contrast effects in a single mathematical formulation. The predictions of the CIWaM were tested by means of several color and brightness induction experiments, which showed an acceptable agreement between model predictions and psychophysical data.