Small-scale fisheries in ecologically sensitive areas in Latin America and the Caribbean: Do marine protected areas benefit fisheries governance?

Many small-scale fisheries (SSFs) in Latin America and the Caribbean (LAC) operate in ecologically sensitive areas, where balancing conservation and resource use is challenging. 'Multiple-use' marine protected areas (MPAs) have been implemented to accommodate SSFs (among other uses) within areas designated for conservation, creating opportunities and challenges for SSF governance. We analyzed eleven case studies from LAC to explore: (1) how different MPA institutional designs affect key aspects of SSF governance and (2) the links between these effects and the type of initiative that promoted MPA establishment (origin). Results indicate that the existence of an MPA benefited SSF governance in many ways, with more pronounced positive effects in MPAs with mixed to bottom-up origin supported by well-organized fishing groups. In addition, the presence of supportive MPA authorities that leveraged local capacities and initiatives and adopted flexible and collaborative governance systems made a difference in several cases. Lessons for integrating MPA and SSF governance are drawn.

Prevalence of Chagas disease among Latin American immigrants in non-endemic countries: an updated systematic review and meta-analysis.

Background: Chagas disease (CD), endemic in 21 Latin American countries, has gradually spread beyond its traditional borders due to migratory movements and emerging as a global health concern. We conducted a systematic review and meta-analysis of available data to establish updated prevalence estimates of CD in Latin American migrants residing in non-endemic countries. Methods: A systematic search was conducted in MEDLINE/PubMed, Embase, Cochrane Library, Scopus, Web of Science, and LILACS via Virtual Health Library (Biblioteca Virtual em Saúde - BVS), including references published until November 1st, 2023. Pooled prevalence estimates and 95% confidence intervals (CI) were calculated using random effect models. Heterogeneity was assessed by the chi-square test and the I2 statistic. Subgroup analyses were performed to explore potential sources of heterogeneity among studies. The study was registered in the PROSPERO database (CRD42022354237). Findings: From a total of 1474 articles screened, 51 studies were included. Studies were conducted in eight non-endemic countries (most in Spain), between 2006 and 2023, and involving 82,369 screened individuals. The estimated pooled prevalence of CD in Latin American migrants living in non-endemic countries was 3.5% (95% CI: 2.5-4.7; I2: 97.7%), considering studies in which screening was indicated simply because the person was Latin American. Per subgroups, the pooled CD prevalence was 11.0% (95% CI: 7.7-15.5) in non-targeted screening (unselected population in reference centers) (27 studies); in blood donors (4 studies), the pooled prevalence was 0.8% (95% CI: 0.2-3.4); among people living with HIV Latin American immigrants (4 studies) 2.4% (95% CI: 1.4-4.3) and for Latin American pregnant and postpartum women (14 studies) 3.7% (95 CI: 2.4-5.6). The pooled proportion of congenital transmission was 4.4% (95% CI: 3.3-5.8). Regarding the participants' country of origin, 7964 were from Bolivia, of which 1715 (21,5%) were diagnosed with CD, and 21,304 were from other Latin American countries of which 154 (0,72%) were affected. Interpretation: CD poses a significant burden of disease in Latin American immigrants in non-endemic countries, suggesting that CD is no longer a problem limited to the American continent and must be considered as a global health challenge. Funding: This study was funded by the World Heart Federation, through a research collaboration with Novartis Pharma AG.

Acanthoatractis xinguensis n. gen., n. sp. (Nematoda: Cosmocercoidea: Atractidae) parasite of yellow-spotted Amazon river turtle, Podocnemis unifilis Troschel (Testudines: Podocnemididae) in Brazilian Amazon.

Nematodes collected from the stomach of the yellow-spotted turtle Podocnemis unifilis Troschel, 1848 (Testudinidae) in the Brazilian state of Pará are assigned to a new genus, allocated to the family Atractidae (Cosmocerdoidea). Acanthoatractis n. gen. differs from all other genera of Atractidae based on the combination of the following morphological characters: cephalic extremity surrounded by eight bifurcated, wrench-shaped sclerotized structures arranged in a circle; oral opening encircled by two sclerotized pieces with pointed ends and a median portion with a pair of hooks; in males the larger (left) spicule is narrower in the middle third and the gubernaculum is absent. The type species, Acanthoatractis xinguensis n. gen., n. sp., has nine pairs of caudal papillae and a single papilla anterior to the cloacal lip. The new species is the seventh record of an atractid genus parasitizing P. unifilis.

Correction: Photoluminescence modification of europium(III)-doped MAl2O4 (M = Zn, Mg) spinels induced by Ag@SiO2 core-shell nanoparticles.

Correction for 'Photoluminescence modification of europium(III)-doped MAl2O4 (M = Zn, Mg) spinels induced by Ag@SiO2 core-shell nanoparticles' by Rodrigo A. Valenzuela-Fernández et al., Nanoscale, 2024, https://doi.org/10.1039/d4nr01526f.

Mechanical force activates the light-dependent channels TRP and TRPL in excised patches from the rhabdomere of Drosophila photoreceptors.

Drosophila phototransduction in light-sensitive microvilli involves a metabotropic signaling cascade. Photoisomerized rhodopsin couples to G-protein, activating phospholipase C, which cleaves phosphatidylinositol bisphosphate (PIP2) into inositol trisphosphate, diacylglycerol (DAG) and a proton. DAG is converted into phosphatidic acid by DAG-kinase and metabolized to L-linoleoyl glycerol (2-LG) by DAG-lipase. This complex enzyme cascade ultimately opens the light-dependent transient receptor potential channels, TRP and TRPL. PIP2, DAG, H+ and 2-LG are possible channel activators, either individually or combined, but their direct participation in channel-gating remains unresolved. Molecular interaction with the channels, modification of the channels' lipid moiety and mechanical force on the channels by changes in the membrane structure derived from light-dependent changes in lipid composition are possible gating agents. In this regard, mechanical activation was suggested, based on a rapid light-dependent contraction of the photoreceptors mediated by the phototransduction cascade. Here, we further examined this possibility by applying force to inside-out patches from the microvilli membrane by changing the pressure in the pipette or pulling the membrane with a magnet through superparamagnetic nanospheres. The channels were opened by mechanical force, while mutant lacking both channels was insensitive to mechanical stimulation. Atomic Force Microscopy showed that the stiffness of an artificial phospholipid bilayer was increased by arachidonic acid and diacylglycerol whereas elaidic acid was ineffective, mirroring their relative effects in channel activity previously observed electrophysiologically. Together, the results are consistent with the notion that light-induced changes in lipid composition alter the membrane structure, generating mechanical force on the channels leading to channel opening.

Rosmarinic acid turned α-syn oligomers into non-toxic species preserving microtubules in Raw 264.7 cells.

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder worldwide, and the therapeutic is focused on several approaches including the inhibition of fibril formation by small compounds, avoiding the formation of cytotoxic oligomers. Thus, we decided to explore the capacity of compounds carrying catechol moieties to inhibit the progression of α-synuclein. Overall, the compounds rosmarinic acid (1), carnosic acid (2), carnosol (3), epiisorosmanol (4), and rosmanol (5) avoid the progression of fibril formation assessed by Thiofavine T (ThT), and atomic force microscopy images showed that morphology is influenced for the actions of compounds over fibrillization. Moreover, ITC experiments showed a Kd varying from 28 to 51 µM, the ΔG showed that the reaction between compounds and α-syn is spontaneous, and ΔH is associated with an exothermic reaction, suggesting the interactions of hydrogen bonds among compounds and α-syn. Docking experiments reinforce this idea showing the intermolecular interactions are mostly hydrogen bonding within the sites 2, 9, and 3/13 of α-synuclein, and compounds 1 and 5. Thus, compound 1, rosmarinic acid, interestingly interacts better with site 9 through catechol and Lysines. In cultured Raw 264. 7 cells, the presence of compounds showed that most of them can promote cell differentiation, especially rosmarinic acid, and rosmanol, both preserving tubulin cytoskeleton. However, once we evaluated whether or not the aggregates pre-treated with compounds could prevent the disruption of microtubules of Raw 264.7 cells, only pre-treated aggregates with rosmarinic acid prevented the disruption of the cytoskeleton. Altogether, we showed that especially rosmarinic acid not only inhibits α-syn but stabilizes the remaining aggregates turning them into not-toxic to Raw 264.7 cells suggesting a main role in cell survival and antigen processing in response to external α-syn aggregates.

HOTSPOT: An ad hoc teamwork platform for mixed human-robot teams.

Ad hoc teamwork is a research topic in multi-agent systems whereby an agent (the "ad hoc agent") must successfully collaborate with a set of unknown agents (the "teammates") without any prior coordination or communication protocol. However, research in ad hoc teamwork is predominantly focused on agent-only teams, but not on agent-human teams, which we believe is an exciting research avenue and has enormous application potential in human-robot teams. This paper will tap into this potential by proposing HOTSPOT, the first framework for ad hoc teamwork in human-robot teams. Our framework comprises two main modules, addressing the two key challenges in the interaction between a robot acting as the ad hoc agent and human teammates. First, a decision-theoretic module that is responsible for all task-related decision-making (task identification, teammate identification, and planning). Second, a communication module that uses natural language processing to parse all communication between the robot and the human. To evaluate our framework, we use a task where a mobile robot and a human cooperatively collect objects in an open space, illustrating the main features of our framework in a real-world task.

Photoluminescence modification of europium(III)-doped MAl2O4 (M = Zn, Mg) spinels induced by Ag@SiO2 core-shell nanoparticles.

In recent years, there has been an increasing interest in developing new inorganic compounds with exceptional properties for advanced materials. Specifically, compounds containing europium have attracted much attention due to their luminescent properties. These compounds are used in electronics, biotechnology, medicine, and catalysis. Eu is known for its characteristic red emission, which can be influenced by the environment. This study investigates the surface-enhancement luminescence of europium-doped spinel oxides using modified surface with silver (Ag@SiO2 core-shell) nanoparticles as the enhancers. The europium-doped spinels were synthesized through a sol-gel method, and characterization techniques were used to analyze their structure and morphology. Photoluminescence spectra exhibited characteristic Eu3+ transitions, with the hypersensitive transition being the most prominent. The interaction with an Ag@SiO2 modified-surface led to a significant increase in photoluminescence. The study also analyzed the photoluminescence excitation and lifetimes of the oxides, leading to a 7.3-fold increase in photoluminescence. The improvements observed in the luminescence of these tailor-made materials show their potential interest in next-generation technologies.

Structural Characterization and Magnetic Behavior Due to the Cationic Substitution of Lanthanides on Ferrite Nanoparticles.

A new series of [Fe3-xLnx]O4 nanoparticles, with Ln = Gd; Dy; Lu and x = 0.05; 0.1; 0.15, was synthesized using the coprecipitation method. Analyses by X-ray diffraction (XRD), Rietveld refinement, and high-resolution transmission electron microscopy (HRTEM) indicate that all phases crystallized in space group Fd3¯m, characteristic of spinels. The XRD patterns, HRTEM, scanning electron microscopy analysis (SEM-EDS), and Raman spectra showed single phases. Transmission electron microscopy (TEM), Rietveld analysis, and Scherrer's calculations confirm that these materials are nanoparticles with sizes in the range of ~6 nm to ~13 nm. Magnetic measurements reveal that the saturation magnetization (Ms) of the as-prepared ferrites increases with lanthanide chemical substitution (x), while the coercivity (Hc) has low values. The Raman analysis confirms that the compounds are ferrites and the Ms behavior can be explained by the relationship between the areas of the signals. The magnetic measurements indicate superparamagnetic behavior. The blocking temperatures (TB) were estimated from ZFC-FC measurements, and the use of the Néel equation enabled the magnetic anisotropy to be estimated.

Ophiotaenia karipuna n. sp. (Eucestoda: Proteocephalidae), a parasite of Erythrolamprus miliaris (Linnaeus, 1758), with redescription of Ophiotaenia arandasi (Santos and Rolas, 1973) from the Brazilian Amazon.

Ophiotaenia is the most diverse genus among proteocephalids, composed of species commonly found parasitizing snakes worldwide. However, the diversity of Ophiotaenia in the Neotropical region is still underestimated. This study describes Ophiotaenia karipuna n. sp. found parasitizing Erythrolamprus miliaris in the State of Amapá, Brazil. Additionally, we redescribe Ophiotaenia arandasi based on a re-examination of type series and newly collected material from Erythrolamprus taeniogaster in the State of Pará, Brazil. The new species differs from its congeners in the following characteristics: scolex width, number of testes, relative length of the cirrus-sac, absence of a vaginal sphincter, presence of a vestigial apical organ resembling a sucker, and relative size of the ovary in relation to the surface of the proglottid. Furthermore, we provide taxonomic information for Ophiotaenia arandasi not reported in the original description, including morphology of embryophore, uterine development, and the absence of the vaginal sphincter in the species. Ophiotaenia karipuna n. sp. represents the 21st- species described in snakes -from the Neotropical region and the first formally described in the Brazilian Amazon. Additionally, we provide the first ultrastructural analysis, a new host, and locality records for O. arandasi.

Prevalence of clinical forms of Chagas disease: a systematic review and meta-analysis - data from the RAISE study.

Background: There is a lack of up-to-date estimates about the prevalence of Chagas disease (ChD) clinical presentations and, therefore, we aimed to assess the prevalence of clinical forms of ChD among seropositive adults, pooling available data. Methods: A systematic review was conducted in Medline, Embase, Biblioteca Virtual em Saúde and Cochrane databases looking for studies published from 1990 to August 2023, which investigated the prevalence of ChD clinical forms among seropositive adults, including: (i) indeterminate phase, (ii) chronic Chagas cardiomyopathy (CCM), (iii) digestive and (iv) mixed (CCM + digestive) forms. Pooled estimates and 95% confidence intervals (CI) were calculated using random-effects models. Studies quality and risk of bias was assessed with the Leboeuf-Yde and Lauritsen tool. Heterogeneity was assessed with the I2 statistic. The study was registered in the PROSPERO database (CRD42022354237). Findings: 1246 articles were selected for screening and 73 studies were included in the final analysis (17,132 patients, 44% men). Most studies were conducted with outpatients (n = 50), followed by population-based studies (n = 15). The pooled prevalence of the ChD clinical forms was: indeterminate 42.6% (95% CI: 36.9-48.6), CCM 42.7% (95% CI: 37.3-48.3), digestive 17.7% (95% CI: 14.9-20.9), and mixed 10.2% (95% CI: 7.9-13.2). In population-based studies, prevalence was lower for CCM (31.2%, 95% CI: 24.4-38.9) and higher for indeterminate (47.2%, 95% CI: 39.0-55.5) form. In meta-regression, age was inversely associated with the prevalence of indeterminate (ß = -0.05, P < 0.001) form, and directly associated with CCM (ß = 0.06, P < 0.001) and digestive (ß = 0.02, P < 0.001) forms. Heterogeneity was overall high. Interpretation: Compared to previous publications, our pooled estimates show a higher prevalence of CCM among ChD seropositive patients, but similar rates of the digestive form. Funding: This study was funded by the World Heart Federation, through a research collaboration with Novartis Pharma AG.

The Burden of Chagas Disease in the Contemporary World: The RAISE Study.

Chagas disease (ChD), a Neglected Tropical Disease, has witnessed a transformative epidemiological landscape characterized by a trend of reduction in prevalence, shifting modes of transmission, urbanization, and globalization. Historically a vector-borne disease in rural areas of Latin America, effective control measures have reduced the incidence in many countries, leading to a demographic shift where most affected individuals are now adults. However, challenges persist in regions like the Gran Chaco, and emerging oral transmission in the Amazon basin adds complexity. Urbanization and migration from rural to urban areas and to non-endemic countries, especially in Europe and the US, have redefined the disease's reach. These changing patterns contribute to uncertainties in estimating ChD prevalence, exacerbated by the lack of recent data, scarcity of surveys, and reliance on outdated models. Besides, ChD's lifelong natural history, marked by acute and chronic phases, introduces complexities in diagnosis, particularly in non-endemic regions where healthcare provider awareness is low. The temporal dissociation of infection and clinical manifestations, coupled with underreporting, has rendered ChD invisible in health statistics. Deaths attributed to ChD cardiomyopathy often go unrecognized, camouflaged under alternative causes. Understanding these challenges, the RAISE project aims to reassess the burden of ChD and ChD cardiomyopathy. The project is a collaborative effort of the World Heart Federation, Novartis Global Health, the University of Washington's Institute for Health Metrics and Evaluation, and a team of specialists coordinated by Brazil's Federal University of Minas Gerais. Employing a multidimensional strategy, the project seeks to refine estimates of ChD-related deaths, conduct systematic reviews on seroprevalence and prevalence of clinical forms, enhance existing modeling frameworks, and calculate the global economic burden, considering healthcare expenditures and service access. The RAISE project aspires to bridge knowledge gaps, raise awareness, and inform evidence-based health policies and research initiatives, positioning ChD prominently on the global health agenda.

A New Species of Cosmocerca Diesing, 1861 (Nematoda: Cosmocercidae) in Elachistocleis haroi Pereyra, Akmentins, Laufer, and Vaira, 2013 (Amphibia: Microhylidae) from South American Chaco.

PURPOSE: Cosmocercids are common nematodes that parasitize the digestive tract and lungs of amphibians and reptiles around the world. They are commonly found in leptodactylid and bufonid anurans in South America, primarily in Brazil and Argentina. This paper describes a new species of genus Cosmocerca based on specimens collected in a microhylid from the Dry Chaco ecoregion. METHODS: A total of 18 specimens of Elachistocleis haroi were collected in October 2011 in Chaco province and in December 2021 and March 2022 in Formosa province, Argentina, both areas of the Dry Chaco ecoregion. The morphology of the nematodes was studied in detail using light microscopy and scanning electron microscopy. RESULTS: One hundred and fifty-one nematodes were collected from the large intestines of E. haroi. Based on the morphology of the caudal papillae (rosette papillae and plectanes), the presence of two spicules and the absence of caudal alae in males, and the presence of two prodelphic ovaries in females, these specimens were allocated to the genus Cosmocerca. However, they presented unique characteristics that differentiate them from all known species. Cosmocerca wichiorum sp. nov. is similar to C. archeyi, C. australis, C. sardiniae, C. zugi, and C. leytensis by having four pairs of plectanes, but can be easily distinguished from all of them by the type, number, and arrangement of the precloacal (non-plectanes), adcloacal and postcloacal papillae, by the length of the spicules and by its different zoogeographical distribution. CONCLUSION: This is the 14th species of the genus Cosmocerca described in South America and the first one for the microhylid E. haroi from the Dry Chaco ecoregion.

A new species of Aplectana Railliet & Henry, 1916 (Nematoda: Cosmocercidae) in the Brazilian Amazon and the taxonomic status of Aplectana longa.

Nematodes of the genus Aplectana Railliet & Henry, 1916 are common parasites of the digestive tract of amphibians and reptiles in the Neotropical region. During a parasite survey on Boana boans (Linnaeus, 1758), we found specimens of nematodes with Aplectana characteristics. We observed a set of characteristics that differs the species of our study from its congeners, and the present study describes a new species of Aplectana parasite of B. boans using light microscopy and scanning electron microscopy. Aplectana pella n. sp. has lateral alae and somatic papillae in males and females; males have equal short spicules, and the gubernaculum is absent. The arrangement of pairs of caudal papillae also differs from other species (2 precloacal,1 adcloacal, and 5 postcloacal+1 unpaired). In females, the vulva is simple, with non-prominent lips, and equatorial. This is the first record of the genus Aplectana parasitizing B. boans and the 58th species described for this genus. Additionally, we added the precloacal papillae pattern of A. delirae, and based on morphological and morphometric characteristics, we propose the reallocation of Aplectana longa to the genus Oxyascaris.

A new species of Oxyascaris Travassos, 1920 (Nematoda: Cosmocercoidea) parasite of Leptodeira annulata (Serpentes: Colubridae) from Brazil, with a key to the species of the genus.

During a helminthological survey of snakes in the Cerrado Biome in Maranhão State, Brazil, we found intestinal nematodes in Leptodeira annulata (Linnaeus), belonging to the genus Oxyascaris Travassos, 1920. We observed that the specimens found are distinct from their congeners by the combination of presented characters, mainly the cuticular expansion at the anterior region of the body, presence of a single papilla at the anterior cloacal lip, number, and arrangement of caudal papillae, presence of somatic papillae along body cuticle, as well as some morphometric characters. Thus, we describe the new species using light and scanning electron microscopy and, revise the morphological characters used to identify Oxyascaris spp. and propose a key to the species of the genus. Therefore, we describe the seventh species in the genus, the second reported to parasitize snakes, the sixth species recorded in Brazil, and the first described in the Cerrado Biome.

Orientatractis bowseri n. sp. (Nematoda: Cosmocercoidea: Atractidae) parasite of Peltocephalus dumerilianus (Schweigger) (Testudines: Podocnemididae) from the Brazilian Amazon.

Peltocephalus dumerilianus (Schweigger) is a diurnal freshwater turtle widely distributed in the Orinoco and Amazon River basins in Brazil, Colombia, Peru, Ecuador, Venezuela, and French Guiana. During a helminthological survey of freshwater turtles from the Brazilian Amazon, numerous nematodes with characteristics of the genus Orientatractis Petter, 1966 were recovered from the stomach of Peltocephalus dumerilianus. These nematodes were different from all congeneric species, and we describe herein. Orientatractis bowseri n. sp. differs from all known species of the genus by having dorsal cuticular projections on the posterior region of the females, distribution of caudal papillae and by having papilla-like ornamentations on the cuticle distributed from the mid-esophagus to the mid portion of the body. This study represents the fourth specie of the genus Orientatractis reported in Brazil, the seventh species of Orientatractis in the Neotropical region, and the third found infecting freshwater turtles in Brazil.

The economic burden of Chagas disease: A systematic review.

BACKGROUND: Chagas disease (CD) is a neglected disease affecting millions worldwide, yet little is known about its economic burden. This systematic review is part of RAISE project, a broader study that aims to estimate the global prevalence, mortality, and health and economic burden attributable to chronic CD and Chronic Chagas cardiomyopathy. The objective of this study was to assess the main costs associated with the treatment of CD in both endemic and non-endemic countries. METHODS: An electronic search of the Medline, Lilacs, and Embase databases was conducted until 31st, 2022, to identify and select economic studies that evaluated treatment costs of CD. No restrictions on place or language were made. Complete or partial economic analyses were included. RESULTS: Fifteen studies were included, with two-thirds referring to endemic countries. The most commonly investigated cost components were inpatient care, exams, surgeries, consultation, drugs, and pacemakers. However, significant heterogeneity in the estimation methods and presentation of data was observed, highlighting the absence of standardization in the measurement methods and cost components. The most common component analyzed using the same metric was hospitalization. The mean annual hospital cost per patient ranges from $25.47 purchasing power parity US dollars (PPP-USD) to $18,823.74 PPP-USD, and the median value was $324.44 PPP-USD. The lifetime hospital cost per patient varies from $209,44 PPP-USD for general care to $14,351.68 PPP-USD for patients with heart failure. DISCUSSION: Despite the limitations of the included studies, this study is the first systematic review of the costs of CD treatment. The findings underscore the importance of standardizing the measurement methods and cost components for estimating the economic burden of CD and improving the comparability of cost components magnitude and cost composition analysis. Finally, assessing the economic burden is essential for public policies designed to eliminate CD, given the continued neglect of this disease.

Characterization of biofilm formation by Exiguobacterium strains in response to arsenic exposure.

IMPORTANCE: In this work, we characterized the composition, structure, and functional potential for biofilm formation of Exiguobacterium strains isolated from the Salar de Huasco in Chile in the presence of arsenic, an abundant metalloid in the Salar that exists in different oxidation states. Our results showed that the Exiguobacterium strains tested exhibit a significant capacity to form biofilms when exposed to arsenic, which would contribute to their resistance to the metalloid. The results highlight the importance of biofilm formation and the presence of specific resistance mechanisms in the ability of microorganisms to survive and thrive under adverse conditions.

A new species of Orientatractis (Nematoda: Cosmocercoidea: Atractidae) parasite of Yellow-Spotted Amazon River Turtle, Podocnemis unifilis Troschel, 1848 (Testudines: Podocnemididae) in Brazilian Amazon.

The current study describes a new species of nematode, Orientatractis matosi n. sp. (Atractidae), from the stomach and large intestine of Podocnemis unifilis Troschel, 1848 (Testudinidae), collected in the Tocantins and Xingu rivers in the Brazilian state of Pará. The new species was described using light and scanning electron microscopy and differs from its congeners mainly in the number and distribution of the male caudal papillae and by having a shorter right spicule. Orientatracits matosi n. sp. is the eleventh species of the genus Orientatractis Petter, 1966, the third reported from the Amazon, and the second described from P. unifilis.

α-Synuclein Drives Tau's Cytotoxic Aggregates Formation through Hydrophobic Interactions.

Tau and α-synuclein are proteins involved in pathologies known as tauopathies and synucleinopathies, respectively. Moreover, evidence shows that there is a crosstalk between them as is seen in the brains of individuals with sporadic neurodegenerative disorders. Based on that, we present data showing that the hydrophobic α-peptide 71 VTGVTAVAQKTV82 induces the aggregation of the full-length tau fragment in the absence of heparin assessed by ThT. Moreover, AFM images reveal the presence of straight filaments and amorphous aggregates of full-length tau in the presence of the α-peptide. Additionally, ITC experiments showed the interaction of the α-peptide with tau full-length (441 amino acids),4R (amino acids from 244 to 369), and both hexapeptides 275 VQIINK280 and 306 VQIVYK311 through hydrophobic interactions. The Raman spectroscopy spectra showed conformational changes in the Amide region in the aggregates formed with full-length tau and α-syn peptide. Furthermore, the incubation of extracellular aggregates with N2a cells showed morphological differences in the cellular body and the nucleus suggesting cell death. Moreover,, the incubation of different types of aggregates in cell culture provokes the release of Lactate dehydrogenase (LDH). Altogether, we found that α-synuclein peptide can drive the aggregation of full-length tau-provoking morphological and structural changes evoking cytotoxic effects.