South America Research Articles

Supplement Use among Hypertensive Patients in Two Rural and Two Urban Health Centers in Guyana, South America

Objective: This study aimed to comparatively assess the knowledge and practices related to the use of dietary supplements as adjunctive treatment and management for hypertension among patients attending two rural and two urban health centers in Guyana. Methods: A cross-sectional, mixed-methods design was employed to evaluate the prevalence, patterns, and motivations for dietary supplement use among 144 hypertensive adults (71 urban, 73 rural) in Guyana, with a focus on the influence of cultural practices on healthcare approaches. Data were collected using a structured questionnaire, which was pretested in a pilot study to ensure validity and reliability. Results: The study sample consisted of 64% female and 36% male participants, with the majority (57%) being over 60 years of age. Urban participants predominantly used vitamin and mineral supplements, demonstrating a statistically significant association between supplement use and blood pressure classification (χ² = 7.16, p = .007). Conversely, rural participants more frequently relied on herbal remedies, particularly for preventive purposes. Conclusion: The findings highlight the need for larger-scale, longitudinal studies to comprehensively explore the interplay between cultural influences, dietary supplement use, and hypertension management in Guyana. Such research is essential for informing the development of culturally sensitive public health interventions to enhance hypertension care in diverse populations.

Vanilla lindmaniana and V. palmarum (Orchidaceae) are distinct allopatric species

Background and aims – With more than 40 species, Brazil is the centre of diversity for Vanilla. Despite the species richness, few studies on species boundaries involving Brazilian taxa have been carried out. Consequently, many species have been synonymized under taxa with a wider distribution. This is the case for V. lindmaniana, a species currently synonymized under V. palmarum. While studying the diversity of Brazilian Vanilla, differences between plants from the Amazonia/Cerrado/Pantanal and Caatinga/Atlantic Forest Biomes were recorded. Material and methods – Detailed descriptions based on herbaria specimens and living material of V. lindmaniana and V. palmarum are provided and a morphological comparison is given. Illustrations of both species based on living plants is provided, and their geographic distributions are presented. Key results – Plants occurring in the Amazon, Cerrado, and Pantanal Biomes correspond to V. lindmaniana, while V. palmarum occurs in the Caatinga and Atlantic Forest Biomes. Vanilla lindmaniana is distinguished from V. palmarum by several vegetative and reproductive characteristics, such as the size of leaves and flower structures, and the shape of the fruits. Characteristics associated to pollination strongly differ between both taxa. Vanilla lindmaniana is ornithophilous, while the labellar morphology of V. palmarum suggests pollination by bees. Both species occur as epiphytes on palms: Vanilla lindmaniana predominantly on Acrocomia, Attalea, and Mauritia, while V. palmarum on Elaeis and Syagrus. Both V. lindmaniana and V. palmarum are assessed as Endangered. Conclusion – Appraisal of reproductive and vegetative characteristics from living specimens is crucial in delimitating species boundaries in Vanilla. Species delimitation based on ecological divergencies, plus geographic disjunctions have advanced the current evaluation and understanding of diversity in this economically and ecologically important orchid genus. All evidence reveals that V. lindmaniana is distinct from V. palmarum. Vanilla palmarum is endemic to Brazil, while V. lindmaniana is widely distributed throughout South America.

Mechanisms Behind the Long‐Distance Diurnal Offshore Precipitation Propagation in Northwestern South America

Mechanisms Behind the Long‐Distance Diurnal Offshore Precipitation Propagation in Northwestern South America

Seahorses as flagship species in the largest hypersaline lagoon in South America

Seahorses as flagship species in the largest hypersaline lagoon in South America

Risk Assessment of Global Animal Melioidosis Under Current and Future Climate Scenarios

Melioidosis is a zoonotic disease that is caused by Burkholderia pseudomallei, which is a serious public health and safety risk. In order to explore the global animal melioidosis risk distribution and its dynamic response to future climate scenarios, we collected global data about reported animal incidence sites. Data regarding the density of Burkholderia pseudomallei in the environment were created by collecting and sorting information about the Burkholderia pseudomallei occurrence sites in contaminated air, soil, and water. Combined with bioclimatic variables, the maximum entropy (MaxEnt) niche was modeled for global animal melioidosis. The findings indicate that under current bioclimatic conditions, global animal melioidosis risk regions are concentrated between 30° S and 30° N, with high-risk areas being mainly in Central America, the northern part of South America, and eastern and southern India, among others. Most countries will expand their risk regions under future climatic scenarios. Melioidosis risk expanding towards higher northern latitudes has led to new epidemic areas. In addition, the melioidosis risk area will contract in some areas. Therefore, we have provided a basis for global melioidosis surveillance and propose feasible strategies for prevention and control in high-risk regions, which will help countries to carry out targeted surveillance and prevention to reduce risks and losses.

Feasting on fish. Specialized function of pre-colonial pottery of the Cerritos mound builders of southern Brazil.

Some of the oldest coastal pottery in South America is found in the Pampas region of southern Brazil, Uruguay and Argentina. In the region's extensive estuarine systems pre-colonial indigenous groups built earthen mounds, known as Cerritos, from ca. 4700 BP. The Cerritos have multifunctional purposes, and while pottery was widely used, its role in the economic or ritual life of the mound builders remains uncertain. Intriguingly, molecular and isotopic characterization of food residues from Cerritos ceramics shows that vessels were used for either cooking estuarine fish, or plant products. Microbial-derived lipids were predominantly associated with the latter, suggesting that plants were fermented, presumably to make alcoholic beverages. We suggest that dispersed communities were drawn to the mounds seasonally to exploit and celebrate the return of migrating fish. This finding is supported by the diversity of stable isotope values of human remains recovered from Cerritos and sheds new light on the lifeways of these pre-colonial groups.

Brown Spider Venom Phospholipases D: From Potent Molecules Involved in Pathogenesis of Brown Spider Bites to Molecular Tools for Studying Ectosomes, Ectocytosis, and Its Applications

Accidents caused by Loxosceles spiders, commonly known as brown spiders, are frequent in warm and temperate regions worldwide, with a higher prevalence in South America and the southern United States. In the venoms of species clinically associated with accidents, phospholipases D (PLDs) are the most expressed toxins. This classification is based on the toxins’ ability to cleave various phospholipids, with a preference for sphingomyelin. Studies using purified PLDs have demonstrated that these enzymes cleave phospholipids from cells, producing derivatives that can activate leukocytes. A dysregulated inflammatory response is the primary effect following envenomation, leading to dermonecrosis, which is histopathologically characterized by aseptic coagulative necrosis—a key feature of envenomation. Although advances in understanding the structure–function relationship of enzymes have been achieved through molecular biology, heterologous expression, site-directed mutations, crystallography, and bioinformatic analyses—describing PLDs in the venoms of various species and highlighting the conservation of amino acid residues involved in catalysis, substrate binding, and magnesium stabilization—little is known about the cellular biology of these PLDs. Studies have shown that the treatment of various cells with recombinant PLDs stimulates the formation of ectosomes and ectocytosis, events that initiate a cascade of intracellular signaling in PLD-binding cells and lead to the release of extracellular microvesicles. These microvesicles may act as signalosomes for other target cells, thereby triggering an inflammatory response and dermonecrosis. In this review, we will discuss the biochemical properties of PLDs, the target cells that bind to them, and the ectocytosis-dependent pathophysiology of envenoming.

Development of a set of monosomic alien addition lines from Gossypium raimondii in Gossypium hirsutum toward breeding applications in cotton

BackgroundGossypium raimondii Ulbr is a diploid wild cotton (2n = 26, D5D5) that originated in west-central Peru of South America and possesses desirable characteristics that are absent in the Upland cotton G. hirsutum. Many beneficial genes were lost from G. hirsutum in the process of domestication, leading to a narrowed genetic base and greater vulnerability to biotic and abiotic stresses. This genetic base can be expanded through distant hybridization using the superior genes of G. raimondii.ResultsIn this study, putative hexaploid F1 plants of G. hirsutum - G. raimondii were generated by interspecific hybridization. Analysis of its mitotic metaphase plates revealed the presence of 78 chromosomes, with each of the six chromosome-specific fluorescence in situ hybridization (FISH) probes (3D5, 5D5, 6D5, 7D5, 9D5, and 10D5) of G. raimondii exhibiting bright and distinct signals on its respective pair of chromosomes. Then, the fertile hexaploid F1 plants were continuously backcrossed with G. hirsutum and a set of G. hirsutum - G. raimondii monosomic alien addition lines (MAALs) were developed using SSR markers in successive backcrosses and self-crossing from BC2F1 to BC4F2. These MAALs were confirmed by chromosome-specific anchored SSRs and FISH. This set of MAALs exhibited abundant variation in morphological traits, agronomic characteristics, yield, and fiber quality traits, as well as in drought and salt resistance at seedling stage. Notably, MAAL_9D5 and MAAL_10D5 demonstrated excellent fiber length (FL), fiber uniformity (FU), fiber strength (FS), micronaire value, and fiber elongation (FE); At seeding stage, MAAL_8D5, MAAL9D5, MAAL_10D5, MAAL_12D5, and MAAL_13D5 showed salt resistance potential; while MAAL_1D5, MAAL_3D5, MAAL_4D5, MAAL_7D5, MAAL_8D5, MAAL_12D5, and MAAL_13D5 exhibited drought resistance potential. These MAALs will provide important genetic bridge materials for gene transfer from G. raimondii as well as for the study of Gossypium species genomes and their evolution.ConclusionsA set of Gossypium hirsutum - Gossypium raimondii MAALs were developed and they showed abundant variation in morphological, agronomic, yield, and fiber quality traits, as well as in drought and salt resistance at seedling stage.

Biomass burning emission analysis based on MODIS aerosol optical depth and AeroCom multi-model simulations: implications for model constraints and emission inventories

Abstract. We assessed the biomass burning (BB) smoke aerosol optical depth (AOD) simulations of 11 global models that participated in the AeroCom phase III BB emission experiment. By comparing multi-model simulations and satellite observations in the vicinity of fires over 13 regions globally, we (1) assess model-simulated BB AOD performance as an indication of smoke source–strength, (2) identify regions where the common emission dataset used by the models might underestimate or overestimate smoke sources, and (3) assess model diversity and identify underlying causes as much as possible. Using satellite-derived AOD snapshots to constrain source strength works best where BB smoke from active sources dominates background non-BB aerosol, such as in boreal forest regions and over South America and southern hemispheric Africa. The comparison is inconclusive where the total AOD is low, as in many agricultural burning areas, and where the background is high, such as parts of India and China. Many inter-model BB AOD differences can be traced to differences in values for the mass ratio of organic aerosol to organic carbon, the BB aerosol mass extinction efficiency, and the aerosol loss rate from each model. The results point to a need for increased numbers of available BB cases for study in some regions and especially to a need for more extensive regional-to-global-scale measurements of aerosol loss rates and of detailed particle microphysical and optical properties; this would both better constrain models and help distinguish BB from other aerosol types in satellite retrievals. More generally, there is the need for additional efforts at constraining aerosol source strength and other model attributes with multi-platform observations.

The Role of Anthropogenic Climate Change on March–April–May (MAM) Drought Trends Across Global Land

ABSTRACTUnderstanding the influence of human‐induced climate change on drought is critical for addressing global challenges. This study uses the Standardised Precipitation Index (SPI) and the Standardised Precipitation Evapotranspiration Index (SPEI) to identify detection and attribution of global drought patterns during the March–April–May (MAM) season. SPI focuses on rainfall, while SPEI accounts for both Precipitation and potential evapotranspiration. We analysed spatial trends using ensemble mean data from 15 global climate models in the Coupled Model Intercomparison Project Phase 6 (CMIP6). Simulations incorporating both natural and anthropogenic forcings (ALL) were compared with those limited to natural forcings (NAT) to evaluate human impacts on drought patterns. Results based on SPI from both observational data (OBS) and ALL simulations reveal wetting trends in Southwest Asia, South America, Eastern Europe, and Central Africa, and drying trends in Northwestern Europe, Southeastern China, India, North America, East Africa, and Australia. SPEI shows wetting in Northeast Asia, Europe, Southeastern North America, and Northwest Africa, with drying in North America, Southeastern Africa, Europe, and Southeastern China. Significantly, the drying trends in ALL simulations are stronger than in NAT, highlighting anthropogenic climate change as a key driver of worsening drought patterns. Detection analysis confirms a strong ALL signal in SPI and SPEI observations, while NAT remains undetected. Lastly, Severe droughts (indices < −2) were examined, in terms of likelihood ratio in All and NAT, show human activities significantly influence precipitation in Southeast Asia, tropical rainforests, and East Africa, with temperature variations driving droughts in Central Asia and other tropical regions.

Artemisinin pressure in field isolates can select highly resistant Plasmodium falciparum parasites with unconventional phenotype and no K13 mutation.

Artemisinin resistance, which poses a serious threat to malaria control efforts, is monitored in the field by delayed parasite clearance in patients, elevated parasite survival rate in the ring-stage survival assay, and mutations in the Plasmodium falciparum kelch13 gene. However, sporadic cases of artemisinin-resistant malaria do not meet all of these criteria, highlighting that our understanding of artemisinin resistance is still incomplete. Here, we selected for artemisinin resistance in vitro in nine P. falciparum field isolates from Africa, Asia, and South America. Artemisinin pressure selected highly resistant parasites in all lineages, but only one acquired a validated pfkelch13 mutation. Phenotypic tests evidenced an unconventional response of selected parasites that can be artemisinin-resistant only at an advanced ring age, making them undetectable by the standard "0-3 h" test used to monitor resistance. These results highlight the need for broader approaches to artemisinin resistance monitoring.

Postnatal development in a specialized bird: Quantitative and qualitative analysis of pelvic girdle morphological changes in Rhea americana (Aves, Palaeognathae).

The greater rhea (Rhea americana) is the largest bird in South America. It is flightless and cursorial, with a precocial postnatal development. This study aims to describe the postnatal morphological changes in the pelvic girdle of Rhea americana, focusing on ontogenetic scaling and gross anatomy to provide insight into the potential relationship between structure and function in cursorial birds. The pelves of 18 specimens representing four postnatal stages, were studied. Gross anatomical observations and staining methods were used to identify bone and cartilage, providing detailed information about qualitative morphological changes. Quantitative changes were assessed through linear regression analysis using pelvic linear dimensions and body mass to determine allometric growth patterns. The pelvic girdles of immature specimens are characterized by unfused bones, including the vertebrae synsacrales and the medial borders of the ilia, and small cartilaginous areas at the caudal end of the ilium, ischium, pubis, antitrochanter and tuberculum preacetabulare. These immature traits persisted until the most advanced juvenile stages were studied, indicating the slow postnatal growth typical of precocial birds. Similar to other precocial birds, the greater rhea exhibits large bone areas in its pelvic girdle, providing the mechanical strength necessary for locomotion from hatching. The pelvic dimensions showed a combined pattern of allometric and isometric growth related to hindlimb function and body support. The positive allometric growth of the ilium contributed to its increasing verticalization and narrowing, providing an increased dorsoventral surface area for the attachment of the powerful proximal hindlimb muscles. In contrast, the isometric growth of the intertrochanteric width helps in the uniform distribution of loading caused by body mass, providing adequate stability and support.

A new narrower circumscription and a nomenclatural synopsis for Calea subg. Meyeria (Asteraceae: Neurolaeneae)

The studies on Calea subg. Meyeria (Neurolaeneae, Asteraceae), a group from open vegetation in Southeastern South America, recently resulted in the description of novel species and nothospecies. Continued progress on the nomenclatural and taxonomic studies of this subgenus is presented here. A comprehensive bibliography for species described in this section was compiled and revised to allow the proposition of nomenclatural changes. All type specimens were consulted either in person or using high-resolution digital images. Based on these efforts, we propose a narrower circumscription of Calea subg. Meyeria, altering the number of accepted taxa assigned to it from 15 to 9. The subgenus is here proposed to be characterized morphologically by shrubs with a cymose capitulescence, capitula with four or more foliaceous outer phyllaries and cypsela longer than the pappus. As here defined, it comprises eight species (C. funkiana, C. marginata, C. myrtifolia, C. parvifolia, C. phyllolepis, C. pruskiana, C. subintegerrima, and C. triantha) and one nothospecies (C. × parviantha). Altogether, we synonymize four names; propose lectotypifications for two names; recognize three new isolectotypes; and provide corrections for type specimen collection data from six taxa, including collector names, collection date, and locality.

First confirmed record of Catharus ustulatus (Nuttall, 1840), Swainson’s Thrush (Passeriformes, Turdidae), in Paraguay

Catharus ustulatus (Nuttall, 1840) (Swainson’s Thrush), a long-distance migratory songbird, spends its nonbreeding period primarily in northwestern South America and has been listed hypothetically in Paraguay. Here, we provide the first confirmed record of the species in Paraguay, documented by photographs. This find extends the known range of C. ustulatus into the Dry Chaco ecoregion, with potential implications for understanding this species’ nonbreeding distribution and habitat use.

Projected impact of climate change on the future distribution of Larrea species in southern South America

Projected impact of climate change on the future distribution of Larrea species in southern South America

Courtship behavior of a secretive forest tinamou, Tinamus major (Great Tinamou)

Abstract The mating systems of many rainforest birds remain poorly understood, especially those that elude observation in dense forest understories. Here we documented mating behaviors in a pair of Tinamus major (Great Tinamou), a secretive species with a wide distribution across the lowland Central and South American tropics. Despite anecdotal preconceptions that males court females, we observed predominant courtship displays from the putative female tinamou. In this mating ritual recorded in the birds’ natural habitat, only the putative female vocalized in the form of clucking and soft-rolling songs, and courted the putative male with a suite of courtship displays, such as neck-elongation, tail-raising, crouching, and feather-fluffing. In contrast, the putative male watched while standing still, approached, tail-raised, walked away, and mounted the putative female a few times. The clucking song of the putative female had not been described previously but we repeatedly observed this song type immediately before the soft-rolling songs during the courtship interaction. Clucking was of lower frequency and around 10 times shorter than the soft-rolling songs. The clucking and soft-rolling songs sung by the putative female were of lower frequency than the common morning territorial songs recorded in the vicinity. This behavioral auditory analysis of the secretive mating ritual of a rainforest tinamou reveals a previously underappreciated female role in their courtship displays.

Human-environment interaction during the Holocene in Eastern South America: Rapid climate changes and population dynamics.

About 15 years ago, we suggested that the low frequency of archaeological sites dating from the mid-Holocene in several regions of Lowland South America (which was then called the "Archaic Gap") was due to an increase in the magnitude of dry periods related to the mid-Holocene hypsithermal. Since then, data regarding paleoenvironmental reconstructions for this vast area, coupled with an increase in the archaeological knowledge, allow us to reassess the idea of the "Archaic Gap" and redefine both the spatial extent of the phenomenon and its possible causes. Our present analysis aims to present a broader picture of the relations between humans and the environment in Eastern South America since the Late Pleistocene. The obtained results suggest that the extent of the areas that were somewhat depopulated during the mid-Holocene is larger than previously thought; not only Central Brazil, but parts of the Amazon and the Pantanal (close to the Bolivian border) seem to show the same pattern. However, as expected when larger datasets are available, it is possible to perceive oscillations in the archaeological signal that suggest reoccupation of some areas. Although we maintain that the main reasons underlying these patterns are related to climate, they are most probably related to an increase in climatic variability, and not necessarily to an increase in dryness. These observations are of interest to the current debate about the effects of the global warming on human populations.

On Cytheridella whitmani sp. nov. (Crustacea, Ostracoda) from Cape Cod (Massachusetts, USA), with a reappraisal of the taxonomy of the genus

Cytheridella whitmani Martens, sp. nov. is described from lakes on Cape Cod (MA, USA). The species differs from its congeners mainly by the shape of the female carapace and by the morphology of the hemipenis, especially of the distal lobe and the copulatory process. The literature on the genus is reviewed and the synonymy of the fossil Cytheridella boldii Purper, 1974 with the type species C. ilosvayi Daday, 1905, both described from South America, is confirmed. The status of Cytheridella americana (Furtos, 1936) is reverted to that of “uncertain species”. Beside the type species and the new species, the genus currently includes only three further species from Africa: C. monodi Klie, 1936, C. damasi Klie, 1944 (with synonym C. chariessa Rome, 1977), and C. tepida Victor, 1987. The morphology of the new species is discussed in comparison with the congeneric species, especially regarding the valve ornamentation, the structure and function of the third thoracopod, the hemipenis and the caudal ramus. It is suggested that C. whitmani is a recent invasive species in the lakes of the Cape Cod peninsula. Its occurrence at northern latitudes is unexpected, as its congeneric species are consistently (sub-) tropical.

A numerical model for duricrust formation by water table fluctuations

Abstract. Duricrusts are hard mineral layers forming in climatically contrasted environments. They form in tropical to arid environments and can be currently observed all around the world in areas such as Europe, Africa, South America, India, and Australia. In most cases, they cap hills and appear to protect softer layers beneath. Two main hypotheses have been proposed for the formation of duricrusts; i.e. the hydrological or transported model, where the enrichment in the hardening element (iron for ferricretes, silica for silcretes, or calcium carbonates for calcretes) is the product of leaching and precipitation through fluctuations in the water table during contrasted seasonal cycles, and the laterization or in situ model, where the formation of duricrusts is the final compacting stage of laterization. In this article, we present the first numerical geomorphological model for the formation of duricrusts based on the hydrological hypothesis. The model is an extension to an existing regolith formation model, where the position of the water table is used to predict the formation of a hardened layer at a rate set by a characteristic timescale, τ, and over a depth set by the range of fluctuations in the water table, λ. Hardening causes a decrease in surface erodibility, which we introduce in the model as a dimensionless factor, κ, that multiplies the surface transport coefficient of the model. Using the model, we show under which circumstances duricrusts form by introducing two dimensionless numbers that combine the model parameters (λ and τ), as well as parameters representing external forcing like precipitation rate and uplift rate. We demonstrate that when using model parameter values obtained by independent constraints from field observations, hydrology, and geochronology, the model predictions reproduce the observed conditions for duricrust formation. We also show that a strong feedback exists due to duricrust formation on the shape of the regolith and the position of the water table. Finally, we demonstrate that although duricrusts protect elements of the landscape, their efficiency in doing so is significantly lower than their inherent strength.

Psychological well-being, resilience, self-determination and grit: The 'novelty' role in physical education classes.

In recent years, the incorporation of novelty as a psychological need and the study of the frustration of needs have become a recurring theme in the research on psychological needs in the educational environment. Currently, there are two scales available to assess the frustration of basic psychological needs (FBN) in the context of Physical Education. The objectives of the study are (a) to analyse the factor structures of both scales to compare them with each other and (b) to analyse the effect of FBN on resilience, grit and each of the motivational regulations. The study included 1439 high school students (M = 15.03 years; SD = 1.24). The majority of participants were Caucasian 83.4%, African 9.7%, South American 6.1% and Asian 0.8%. The analyses used to examine the factor structure of the scales were exploratory and confirmatory factor analysis, reliability analysis and discriminant validity analysis. Hierarchical linear regression analysis was used to analyse the relationship of FBN. Each of the scales showed greater robustness in its factor structure and reliability (2023, Physical Education and Sport Pedagogy, 1) scale: χ2/gl = 3.62; CFI = .92; NFI = .92; RMSEA = .061; (2020, Revista de Psicología del Deporte, 29, 91) scale: χ2/gl = 2.67; CFI = .96; NFI = .96; RMSEA = .048, SRMR = .037). Additionally, FBN was positively related to less self-determined motivational regulations, while it was negatively related to grit, resilience and more self-determined motivational regulations. Finally, the results highlighted that the (2020, Revista de Psicología del Deporte, 29, 91) scale, showing greater factorial robustness, obtained greater robustness in the relationships with the variables studied.