American Tropics Research Articles

Mechanistic Insight into Anticancer Prowess of Piper Species and their Bioactive Compounds: A Review

Southern Asia boasts a diverse array of Piper species, renowned for their antimicrobial, antioxidant, and anti-inflammatory properties. These plants, also native to the American tropics, have played a significant role in traditional medicine and culinary practices. Notably, Piper longum L., P. nigrum L., and P. betle L. are recognized for their bioactive compounds, particularly alkaloids, which contribute to their beneficial properties. In recent decades, there has been increased focus on studying these plants for their potential anticancer effects, encompassing both direct cytotoxic effects and indirect modulation of the tumor microenvironment. Major scientific literature databases were consulted using appropriate keywords to present a comprehensive and proportionate analysis of the anticancer potential of the three species, including valuable insights into their therapeutic perspectives, molecular mechanisms, and broader applications in cancer treatment. Numerous pharmacological trials on the bioactive components and extracts have underscored their clinical significance, revealing multifaceted actions such as antiproliferative effects, antiangiogenic properties, immunomodulation, antimetastatic activity, induction of apoptosis, and modulation of various signaling pathways in both malignant and non-malignant disorders. Among the explored compounds, piperine and piperlongumine, prominent alkaloids within the Piper genus, have demonstrated notable efficacy in restricting the growth of cancer cells and tumors. This article emphasizes the biomedical and pharmacological findings related to the anticancer properties of the three Piper species, with a focus on their mechanism of action. These insights could open avenues for future clinical scenarios and therapeutic utilization of bioactive substances and extracts derived from these species.

Some factors affecting the reproductive capacity of hair rams in the American Tropics

Some factors affecting the reproductive capacity of hair rams in the American Tropics

Unexpected arboviruses found in an epidemiological surveillance of acute tropical febrile syndrome in the department of Meta, Eastern Colombia

BackgroundNonspecific acute tropical febrile illnesses (NEATFI) are common in the Latin American tropics. Dengue, Chikungunya, Zika, Mayaro, and Usutu, among others, can coexist in the American tropics. This study aimed to surveil the arboviruses that cause| acute febrile syndrome in patients in the Meta department, Colombia. MethodsBetween June 2021 and February 2023, an epidemiological surveillance study was conducted in the Llanos of the Meta department in Eastern Colombia. ResultsOne hundred patients in the acute phase with typical prodromal symptoms of NEATFI infection who attended the emergency department of the Villavicencio Departmental Hospital were included. ELISA tests were performed for Dengue, Usutu, Chikungunya, and Mayaro. RT-qPCR was performed to detect the arboviruses Usutu, Dengue, Zika, Mayaro, and Oropouche. The seroprevalence for the Chikungunya, Mayaro, and Usutu viruses was 41 % (28/68), 40 % (27/67), and 62 % (47/75), respectively. Seroconversion for Chikungunya was observed in one patient; two seroconverted to Mayaro and one to Usutu. The NS5 gene fragment of the Usutu virus was detected in nine febrile patients. RT-qPCR of the remaining arboviruses was negative. The clinical symptoms of the nine Usutu-positive patients were very similar to those of Dengue, Chikungunya, Zika, and Mayaro infections. ConclusionsThe pervasive detection of unexpected viruses such as Usutu and Mayaro demonstrated the importance of searching for other viruses different from Dengue. Because Usutu infection and Mayaro fever have clinical features like Dengue, a new algorithm should be proposed to improve the accuracy of acute tropical fevers.

Isolated, neglected, and likely threatened: a new species of Magoniella (Polygonaceae) from the seasonally dry tropical forests of Northern Colombia and Venezuela revealed from nuclear, plastid, and morphological data.

Seasonally tropical dry forests (SDTFs) in the American tropics are a highly diverse yet poorly understood and endangered ecosystem scattered from Northern Mexico to Southern Argentina. One floristic element of the STDFs is the genus Magoniella (Polygonaceae), which includes two liana species, M. laurifolia and M. obidensis, which have winged fruits and are distributed from Costa Rica to Southern Brazil. In a field expedition to the SDTFs of the Colombian Caribbean in 2015, morphologically distinctive individuals of Magoniella were found. In this study, we investigated the species boundaries within Magoniella and determined the phylogenetic position of these morphologically distinctive individuals in the tribe Triplaridae. We compiled morphological trait data across 19 specimens of both species and produced newly sequenced nuclear-plastid DNA data for M. obidensis. Morphometric analyses revealed significant differences in fruit length and perianth size among individuals from the Colombian Caribbean compared to M. obidensis and bract length when compared to M. laurifolia. Maximum likelihood analysis of non-conflicting nuclear and plastid datasets placed the Colombian Caribbean individuals as sister to M. obidensis with maximum statistical support. Additionally, pairwise sequence comparisons of the nuclear ribosomal ITS and the lfy2i loci consistently showed 15-point mutations (10 transitions, five transversions) and six 2 bp-long substitutions that differ between M. obidensis and the Colombian Caribbean individuals. Our morphological and molecular evidence thus suggests that the Colombian Caribbean individuals of Magoniella represent a divergent population from M. laurifolia and M. obidensis, which we describe and illustrate as a new species, M. chersina. Additionally, we provide nomenclatural updates for M. laurifolia and M. obidensis. This study highlights the power of combining morphological and molecular evidence in documenting and naming plant diversity.

Taxonomic Revision of the Petiolatum Clade of Elaphoglossum sect. Lepidoglossa (Dryopteridaceae)

This paper provides a monograph of the petiolatum clade of Elaphoglossum Schott ex J. Sm. sect. Lepidoglossa Christ (Dryopteridaceae). This group has been recovered as monophyletic in several molecular phylogenetic analyses. Morphologically, the petiolatum clade is recognized by laminae with resinous dots and flat and/or stellate scales, rhizome scales with acute to filiform-tortuous apices, scales on the proximal portion of the petiole with dark apices, and perines broadly folded, sparsely echinulate with spines less than 1 μm high, or (in E. petiolatum (Sw.) Urb.) with sparse irregular microstructures. Eight species are recognized as a part of the clade, all of them distributed in the American tropics from Mexico to Panama, and one species in the Greater Antilles. Most of the species occur between 1000 and 2500 m elevation in tropical, temperate, and pine-oak forests. Presented here are an identification key, a full synonymy, detailed descriptions, a list of specimens examined, an index to collectors’ names and collection numbers, images of the plants and their main structures, spore microphotographs, and distribution maps for all species. A new combination is made for E. schmitzii (Mett. ex Kuhn) Martínez-Bec. & A. Vasco, and lectotypes are designated for Acrostichum intermedium Fée, E. muelleri (E. Fourn.) C. Chr., E. potosianum Christ, E. pringlei (Davenp.) C. Chr., and E. schmitzii.

HIGH FREQUENCY OF BATS IN THE DIET OF THE BARN OWL TYTO ALBA IN A LOWLAND DRY FOREST IN TOLIMA, COLOMBIA

The cosmopolitan distribution of the Barn Owl Tyto alba and its relatively well documented diet through the study of pellets have provided evidence of the broad diversity of prey it relies on. In most studies, both in tropical and temperate regions, rodents are its main prey, with other small mammals and vertebrates, and insects complementing its diet. Although bats have been recorded in the diet of T. alba at many localities, they seldom represent an important part of its diet. This study describes the diet of a small colony of T. alba from a mosaic of agricultural fields, pastures for cattle ranching and tropical dry forests in Tolima, central Colombia. Overall, we collected 516 pellets between 2016 and 2017 in a non-systematic manner, and recovered 335 skulls of rodents (67%), bats (29%), birds (3%) and shrews (1%), as well as invertebrate prey. The large proportion of bats in the diet of T. alba in this study is only matched by a few other studies, and further documents the wide range of prey included in the diet of this nocturnal raptor. This is one of the first studies on the diet of T. alba in tropical dry forests in Colombia and complements the existing data on its diet in the American tropics and worldwide.

Archaeobotanical evidence supports indigenous cucurbit long-term use in the Mesoamerican Neotropics

The squash family (Cucurbitaceae) contains some of the most important crops cultivated worldwide and has played an important ecological, economic, and cultural role for millennia. In the American tropics, squashes were among the first cultivated crop species, but little is known about how their domestication unfolded. Here, we employ direct radiocarbon dating and morphological analyses of desiccated cucurbit seeds, rinds, and stems from El Gigante Rockshelter in Honduras to reconstruct human practices of selection and cultivation of Lagenaria siceraria, Cucurbita pepo, and Cucurbita moschata. Direct radiocarbon dating indicates that humans started using Lagenaria and wild Cucurbita starting ~ 10,950 calendar years before present (cal B.P.), primarily as watertight vessels and possibly as cooking and drinking containers. A rind directly dated to 11,150–10,765 cal B.P. represents the oldest known bottle gourd in the Americas. Domesticated C. moschata subsequently appeared ~ 4035 cal B.P., followed by domesticated C. pepo ~ 2190 cal B.P. associated with increasing evidence for their use as food crops. Multivariate statistical analysis of seed size and shape show that the archaeological C. pepo assemblage exhibits significant variability, representing at least three varieties: one similar to present-day zucchini, another like present-day vegetable marrow, and a native cultivar without modern analogs. Our archaeobotanical data supports the hypothesis that Indigenous cucurbit use started in the Early Holocene, and that agricultural complexity during the Late Holocene involved selective breeding that encouraged crop diversification.

An arrow in the quiver: evaluating the performance of Hyptis suaveolens (L.) Poit. in different light levels

BackgroundHyptis suaveolens (L.) Poit., native to the American tropics, is a pantropical annual plant and a major invasive species throughout India. It was anticipated that the availability of sunlight, coupled with its superior reproductive potential, persistent propagule bank, and dispersal ability, could lead to an increase in the growth and spread of this invader, thus potentially impeding herbaceous growth and diversity in non-native areas. Clarifying its ecological fitness and competitive performance will be useful to manage the spread of H. suaveolens in natural ecosystems that are facing a wide range of anthropogenic pressures.MethodsThe present study is a three-tier experiment. In the first tier, a field study was conducted to assess the patterns of H. suaveolens abundance and herbaceous species diversity in response to light availability (sun, 842–1072 µmol m–2 s−1 and shade 253–341 µmol m–2 s−1) in the tropical dry deciduous ecosystems in the Vindhyan highlands, India. Furthermore, the impact of H. suaveolens abundance on the resident native and non-native species abundance and diversity was also studied. In the second tier, a randomized common garden experiment was conducted to understand the trait fitness of H. suaveolens in sun (940 µmol m–2 s−1) and shade (300 µmol m–2 s−1) conditions. In the third tier, a plant growth chamber experiment with high-light (940 µmol m–2 s−1) and low-light (300 µmol m–2 s−1) treatments was done to learn how H. suaveolens partitions its biomass between aboveground and belowground plant parts.ResultsThe field study indicated that the sunlit areas had a higher abundance of H. suaveolens and a lower diversity of resident herbaceous species than the shaded areas. The common garden experiment showed that sun-dwelling H. suaveolens individuals performed better in germinative, vegetative, eco-physiological, and reproductive traits than the shade-dwelling individuals. The growth chamber experiment exhibited that plants grown in high-light environment had greater seed germination, seedling recruitment, and aboveground biomass than those grown in low-light environment, whereas plants grown in low-light environment exhibited a higher root mass ratio than the high-light individuals. These results suggest that H. suaveolens individuals mask the understory vegetation owing to higher seedling recruitment, relative growth rate, photosynthetic performance, resource acquisition-allocation, and reproductive output in response to high-light conditions.ConclusionsThe study concludes that light significantly controls the invasive population dynamics of H. suaveolens in dry deciduous forests. In high-light areas, H. suaveolens populations dominate the forest understory with suboptimal shade tolerance. In shade environment, H. suaveolens maintains a persistent soil seed bank along with ‘Oskar individuals’ that become active in response to high-light availability. The modus operandi is a ‘sit and wait’ strategy. The current study provides insights on prioritizing areas for H. suaveolens management that will potentially reduce the risk of biological invasions on the native species diversity of tropical regions.

Chemical and Morphological Characterization of PM10 in an Urbanized Valley in the American Tropics

Chemical and Morphological Characterization of PM10 in an Urbanized Valley in the American Tropics

Characterization and source apportionment of ion and metals in PM10 in an urbanized valley in the American tropics using Principal Component Analysis and Positive Matrix Factorization

Characterization and source apportionment of ion and metals in PM10 in an urbanized valley in the American tropics using Principal Component Analysis and Positive Matrix Factorization

Climate and the Picturesque in the American Tropics by Michael Boyden (review)

Climate and the Picturesque in the American Tropics by Michael Boyden (review)

Biology of Spodoptera eridania (Stoll) in the cultivation of grape (Vitis vinifera L.) under laboratory conditions

The grape crop (Vitis vinifera L.) in the Piura region is infested by pests such as Spodoptera eridania Stoll, a polyphagous species native to the South American tropics. The objective of carrying out the research work was to know basic aspects about its morphology and biology, because there were no records of them in this crop, nor in others in the region. Daily observations were made to determine the duration of the egg incubation period, larval development, and the pupal stage and adult longevity. Once the adults emerged, they mated to establish the oviposition rhythm and reproductive capacity; all these parameters were evaluated for three generations. It was determined that, under laboratory conditions, the development cycle of S. eridania was 34.90 days for the first generation, 31.16 and 28.60 days for the second and third, with an average temperature record of 27.97 °C and relative humidity of 71.86%. The results show that it can be developed in vine plantations and will be useful in planning the work of the crop and in establishing integrated pest management strategies to reduce infestations when they occur.

Inviting oversight: Effects of forest certification on deforestation in the Brazilian Amazon

In the American tropics, logging is almost always highly selective, leaving most of the forest standing and available for future harvest under sustainable forest management. However, forest that has been logged is often more accessible to deforestation agents such as farmers. Thus, areas legally designated for sustainable forest management in reality may be more susceptible to illegal deforestation. Third-party certification of sustainable forest management is one strategy for protecting such forest. In this paper, we estimate the effect of certification by the Forest Stewardship Council (FSC) on deforestation, drawing on data from the years 2001 to 2019. We observe strong selection effects resulting in systematic differences between certified forest areas and other forest areas designated for sustainable forest management, and we find that after controlling for those selection effects, inviting oversight by FSC reduces the probability of deforestation. Our study design compares forests “treated” with FSC certification to “control” forests designated for sustainable forest management but not (yet) certified in the two Brazilian states of Pará and Rondônia. Adopting pixel-based analyses, we first create a matched sample of treated and control pixels and then estimate GLMM models, with two-way fixed effects (TWFE) models as a robustness check.We find that where forest managers have obtained certification and thus invited oversight by FSC auditors, rates of forest loss are lower (although the results are not fully robust across regions). The estimated effects vary across regions, likely due to varying socioeconomic and policy contexts and competing land uses. We conclude that especially in settings of low governance capacity and high deforestation pressure, certification can contribute to long-term forest conservation by reducing deforestation rates.

Stratospheric gravity wave potential energy and tropospheric parameters relationships over South America: a study using COSMIC-2 and METOP radio occultation measurements

Using COSMIC-2 and METOP radio occultation measurements during the years 2020 and 2021, the study presents the first direct and independent relationship between the potential energy (Ep) in the stratosphere, precipitable water vapour (PWV), tropopause heights (TPH), and cold-point heights (CPH) over South America. The South American continent comprises the tropical region, the Andes Mountain range, and mid-latitude climates. The seasonal mean of the potential energy (Ep), the PWV, and the tropopause parameters height (TPH and CPH) were obtained to investigate the relationship between the stratospheric gravity wave (SGW) Ep and the tropospheric parameters (PWV, TPH, and CPH). Around the Andes Mountains to the east, there is significantly less water vapour (PWV < 10 mm) and a relatively high gravity wave Ep (Ep > 8 kJ kg−1). A good correlation of variability was found between the PWV and the lower SGW Ep in summer over the tropical region (± 20◦). Generally, good and strong correlations were observed in the summer and spring, with negative/no correlations in the winter in 2020 and 2021. Also, good and strong correlations between SGW, PWV, and TPH were observed in the summer at {20}^{o}N - {10}^{o}N in 2020 and 2021. Our result demonstrated the possibility that convective activity was a major driver of the tropical gravity waves over South America. In the subtropical (30^circ–40^circ) region, especially in the winter, the tropospheric parameters make little or no contribution to gravity wave activity in the region. The CPH generally showed a no/negative with SGW over the South American tropics. The SGW activities in the tropical region showed an impact on the structure of the tropopause parameters, which could be a result of the convective activity in this region.Graphical

Regional vs. global temperature calibrations for lacustrine BrGDGTs in the North American (sub)tropics: Implications for their application in paleotemperature reconstructions

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) have shown great promise in lacustrine temperature reconstructions across different continents. While brGDGTs have been reported from many different regions and global brGDGT-temperature calibrations have been developed with various methods, southern North America remains an understudied area with little available data. In this study, we analyzed 101 lake surface sediment samples across Mexico and Central America and compared their distributions with those in other lacustrine systems. Nine major brGDGTs were found in all samples. We investigated the relationships between the distribution of the fractional abundances of the nine major brGDGTs and temperature and developed regional calibrations for Mean Annual Temperature using three different approaches, including a novel machine learning method – Ridge Regression. All the regional calibrations provide similar results with very close error ranges (RMSE = 3.1 °C). The majority of global brGDGT-temperature calibrations tend to reconstruct lower temperatures when it is below 15 °C. Interestingly, regional brGDGT calibrations appear to reduce the “cold bias”, but the various global and regional calibrations tested here are not significantly different in their predictive capability.

Two New Muricid Gastropods from the Tropical Americas

Two new large muricids gastropods are named from the American tropics; onefromthe Lucasian Infraprovince of the Magdalenan Subprovince, Panamic Molluscan Province of theEastern Pacific and the other from the Martiniquean Infraprovince of the Grenadian Subprovince, Caribbean Molluscan Province of the Caribbean Sea. The new Panamic species, Neorapanaiwamasai Petuch, Berschauer, and Powell n. sp., is found on a very small stretch of coastline alongBaja California Sur, Mexico. The other species, Phyllonotus bellettii Petuch, Berschauer, andPowell n. sp., is endemic to the islands of Martinique and Guadeloupe, and adjacent smaller islands, in the French West Indies.

Soursop botany, chemical composition and medicinal prospects: a concise review

Soursop (Annona muricata L.) belongs to the family Annonaceae and is reported to have the largest fruit in the genus, Annona. It is best known as “sawasop” in Nigerian vernacular. It is a fruit tree that was in almost every home garden in time past. The need for space, urbanization, inadequate knowledge about the fruit tree potentials, economic relevance and/or preference, has led to its fast eroding out of the urban and semi-urban areas, with relatively fewer stands, compared to decades ago.Soursop has been reported to originate from the American tropics but has been successfully introduced and domesticated around the world. Several past and current researches have been aimed at revealing the medicinal potential and other properties of soursop. Hitherto, the reported ethnomedicinal properties of soursop include but not restricted to analgesic, antibacterial, anticancer, antifungal, antioxidant, antitumor, antiulcer, antiviral, anti-arthritic, anti-diabetic, anti-hypertensive, anti-inflammatory, anti-insomnia, anti-rheumatic, anti-stress, immune enhancing, as well as wound healing capacity. This review highlights a brief description of the botany, chemical composition and the burgeoning need for the utilization of soursop based on its inherent medicinal properties.

Exploring the future of GM technology in sustainable local food systems in Colombia.

The security of Earth's food systems is challenged by shifting regional climates. While agricultural processes are disrupted by climate change, they also play a large role in contributing to destabilizing greenhouse gases. Finding new strategies to increase yields while decreasing agricultural environmental impacts is essential. Tropical agriculture is particularly susceptible to climate change: local, smallholder farming, which provides a majority of the food supply, is high risk and has limited adaptation capacity. Rapid, inexpensive, intuitive solutions are needed, like the implementation of genetically modified (GM) crops. In the Latin American tropics, high awareness and acceptance of GM technologies, opportunities to test GM crops as part of local agricultural educations, and their known economic benefits, support their use. However, this is not all that is needed for the future of GM technologies in these areas: GM implementation must also consider environmental and social sustainability, which can be unique to a locality. Primarily from the perspective of its educators, the potential of a rural Colombian university in driving GM implementation is explored, including the role of this type of university in producing agricultural engineers who can innovate with GM to meet regionally-dependent environmental and cultural needs that could increase their sustainability.

Reproductive characterization of hair ewe in the American tropics: a review part 1

Objective: To carry out a reproductive characterization of the breeds of hair ewe in the tropical region of the Americas. Design/Methodology/Approach: A search of scientific information about the reproductive variables of breeds of hair ewe was carried out and the results were analyzed in the Web of Science, Redalyc, Dialnet, PubMed, SciELO, and Latindex databases. Results: We described and discussed the highly-variable onset of puberty in ewe lambs. Similar results were found in adult ewes regarding the duration and occurrence of the estrous, estrous cycle length, seasonal anestrous, ovulation rate, fertility, gestation, and prolificacy. Study Limitations/Implications: Information about the reproductive variables of breeds of hair ewe is poorly known or non-existent. Findings/Conclusions: The onset of puberty in 15-43 kg ewe lambs ranges from 175 to 335 d of age. The estrous cycle of hair ewe in Mexico lasts 17 d in autumn-winter and 21 d in spring-summer. In Brazil, this cycle lasts 17 d in spring-summer and 18 d in autumn-winter. In the United States of America and Venezuela, the estrous cycle length was similar in both periods of the year. The occurrence of the estrous reached 97.1 % in autumn-winter and 76.5 % in spring-summer. The duration of the estrous ranges from 16 to 52 hours. Seasonal anestrous occurs from May to July. The ovulation rate ranges from 1 to 3 oocytes. The percentage of fertility fluctuates between 80 and 100 % in temperate months and reaches 37 % in warm ones. Gestation lasts from 144 to 152 d. Prolificacy ranges from 1.0 to 2.2 offspring per ewe. The lambing interval ranges from 244 to 294 d.

Recent growth increase in endemic Juglans boliviana from the tropical Andes

The spatial coverage of tree-ring chronologies in tropical South America is low compared to the extratropics, particularly in remote regions. Tree-ring dating from such tropical sites is limited by the generally weak temperature seasonality, complex coloration, and indistinct anatomical morphology in some tree species. As a result, there is a need to complement traditional methods of dendrochronology with innovative and independent approaches. Here, we supplement traditional tree-ring methods via the use of radiocarbon analyses to detect partial missing rings and/or false rings, and wood anatomical techniques to precisely delineate tree-ring boundaries. In so doing we present and confirm the annual periodicity of the first tree-ring width (TRW) chronology spanning from 1814 to 2017 for Juglans boliviana (‘nogal’), a tree species growing in a mid-elevation tropical moist forest in northern Bolivia. We collected 25 core samples and 4 cross-sections from living and recently harvested canopy-dominant trees, respectively. The sampled trees were growing in the Madidi National Park and had a mean age of 115 years old, with certain trees growing for over 200 years. Comparison of (residual and standard) TRW chronologies to monthly climate variables shows significant negative relationships to prior year May-August maximum temperatures (r = −0.54, p < 0.05) and positive relationships to dry season May-October precipitation (r = 0.60, p < 0.05) before the current year growing season. Additionally, the radial growth of Juglans boliviana shows a significant positive trend since 1979. Our findings describe a new and promising tree species for dendrochronology due to its longevity and highlight interdisciplinary techniques that can be used to expand the current tree-ring network in Bolivia and the greater South American tropics.