Biología

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24RNA-SEQ analysis in hiPSC-derived neurons from patients with schizophrenia
(2019-07-26) Stertz, Laura; Pei, Guangsheng; Jia, Peilin; Li, Shenglan; Raventós Vorst, Henriette; Liu, Ying; Zhao, Zhongming; Walss Bass, Consuelo
Background: Human induced pluripotent stem cells (hiPSC) have provided a new way of studying schizophrenia (SZ), by allowing the establishment of brain cellular models accounting for the patient genetic background. Here we conducted an exploratory RNA-sequencing profiling study of cell lines derived from hiPSCs generated from lymphoblastoid cell lines (LCL) of subjects from the population isolate of the Central Valley of Costa Rica (CVCR). Methods: Five cell lines (LCL, hiPSC, NPC, cortical neurons and astrocytes) derived from 6 healthy controls and 7 SZ patients from the CVCR were generated using standard methodology. RNA from these cells was sequenced using Illumina HiSeqTM2500. Normalization and differential expression (DE) analysis were performed using DESeq2 (|FC| > 1.5 e BH corrected p-value < 0.05). Functional enrichment analysis was performed using DAVID 6.8. Results: hiPSC-derived neurons were responsible for 94.4% of the variance seen on DE analyses. We found 454 genes differently expressed on neurons differentiated from SZ compared to HC. Noteworthy, one of these genes was ZNF804A (FDR = 0.032), a strong candidate gene for schizophrenia susceptibility, with solid evidence of association from GWAS. Discussion: ZNF804A is a zinc finger protein has been shown to regulate neurite outgrowth, dendritic spine maintenance and activity-dependent structural plasticity. It is expressed broadly throughout the brain, especially in the developing hippocampus and the cortex, as well as in the adult cerebellum. A great advantage of using iPS-derived cells is that the effect of outside environmental influences, such as use of medications, is removed and only the effects of genetic composition, which is unchanged by transformation, are left. The DE of ZNF804A only on hiPSC-neurons highlight the crucial role that this protein can have on SZ pathology during neuronal development. Functional studies will help us further characterize this mechanism.
(2922) Proposal to conserve the name Loasa rudis (“Nasa rudis”) against L. rhoeadifolia (Loasaceae)
(2022-10-17) Acuña Castillo, Rafael; Weigend, Maximilian
The genus Nasa was established by Weigend in 2006, encompassing species previously classified under Loasa. The distinction between the two genera is supported by the presence of a single bract per flower, a unique structure of the nectar scale, and molecular evidence. Among the widely collected and distributed taxa in Nasa is N. triphylla subsp. rudis, which spans from southern Mexico to Panama. Recent molecular evidence suggests elevating N. triphylla subsp. rudis to species rank, as it is morphologically and phylogenetically closer to N. dyeri than to the type subspecies of N. triphylla. N. rudis and N. dyeri exhibit distinct characteristics in comparison to N. triphylla, including robust basal stems, dark green calli at the base of petioles, and petals with long filiform appendages. N. rudis can be differentiated from N. dyeri by stem characteristics, stinging trichome cover, and pedicel length. The history of nomenclature for this taxon involves various names under Loasa, and the name "Loasa rhoeadifolia" is considered a synonym. Due to the lack of recognizable type material and the established usage of the name "Loasa rudis," it is recommended to conserve the name Loasa rudis for nomenclatural stability and to avoid further confusion.
507. Association of NRXN3 deletion with schizophrenia and bipolar disorder
(2017-05-17) Shavit, Ayal; Gonzalez, Jessica; Chavez, Maricela; Rodriguez, Marco; Camarillo, Cynthia; Ramirez, Mercedez; Zavala, Juan; Contreras Rojas, Javier; Raventós Vorst, Henriette; Flores, Deborah; Jerez, Alvaro; Ontiveros, Alfonso; Nicolini, Humberto; Escamilla, Michael; Gonzalez, Suzanne
Schizophrenia (SZ) and bipolar disorder (BD) are the most severe neuropsychiatric disorders affecting 1.2% and 4.4% of Americans, respectively. Certain genes coding for proteins involved in pre-synaptic machinery are thought to play a role in the pathophysiology of the disorder. Deficits in the calcium channel regulator gene NRXN3 have been associated with behaviors of impulsivity and alcohol and drug dependence, which are traits characteristic of BD and SZ.
846. Human-derived astrocytes from schizophrenia patients express lower levels of GFAP and S100B
(2017-04-29) Stertz, Laura; Raventós Vorst, Henriette; Walss Bass, Consuelo
Schizophrenia (SZ) is a debilitating psychiatric disorder with a worldwide prevalence of 1%; there is a strong genetic component, with an estimated heritability of 70-85%. Glial cells mediate crucial functions in the CNS and alterations in the function of these cells may be an underlying mechanism for SZ development. Here we use astrocytes derived from induced pluripotent stem cells (iPSCs) from subjects from the population isolate of the Central Valley of Costa Rica (CVCR) to explore a role for astrocytes in SZ pathogenesis.
A biogeographical evaluation of high-elevation myxomycete assemblages in the northern Neotropics
(2011-08) Rojas Alvarado, Carlos Alonso; Stephenson, Steven L.; Valverde González, Randall; Estrada Torres, Arturo
This study represented an effort to apply some of the relatively well-known biogeographical and macroecological models to the observed structure of myxomycete assemblages, with emphasis on the northern Neotropical region. A series of 28 experimental plots located in 14 study sites within five different countries was surveyed during two consecutive years using a standard methodology that included both field collections and specimens obtained from moist chamber cultures. Results showed that myxomycetes in high-elevation areas of the northern Neotropics seem to have different levels of preference for macro- and microenvironments, varying degrees of niche breadth and overlap, and different patterns of species occurrence in comparable areas. In a similar manner, species assemblages along a latitudinal gradient that extends from Mexico to Costa Rica showed a decreasing level of similarity with an assemblage studied in the temperate forests of the eastern United Stated and were clearly distinct from an assemblage in Thailand.
A call-and-response system facilitates group cohesion among disc-winged bats
(2013) Chaverri Echandi, Gloriana; Gillam, Erin H.; Kunz, Thomas H.
Acoustic signals are important in maintaining group cohesion, particularly in highly mobile species. For these signals to facilitate group cohesion, individuals must be able to recognize, and respond to, calls emitted by group members. In this study, we document the use and recognition of complementary contact calls in Spix’s disc-winged bat (Thyroptera tricolor), a species known to form very stable social groups despite using an extremely ephemeral roosting resource. This bat uses 2 sets of calls: “inquiry,” which are emitted by flying bats that are seeking roosts or group mates, and “response,” which are produced in reply to an inquiry call by individuals that have already located a roost. Here, we test if bats are capable of discriminating between the inquiry and response calls of group and nongroup mates using playback experiments. Results show that flying bats can discriminate between the inquiry and response calls emitted by group and nongroup members and can maintain contact preferentially with the former. Roosting bats, however, exhibited no preference for group over nongroup members and thus responded indiscriminately. We argue that differences in how individuals respond to calls from group and nongroup members may be partly attributed to the costs associated with flight and the potential benefits of recruiting roost mates.
A ClC Chloride Channel Homolog and Ornithine-Containing Membrane Lipids of Rhizobium tropici CIAT899 Are Involved in Symbiotic Efficiency and Acid Tolerance
(2005) Rojas Jiménez, Keilor Osvaldo; Sohlenkamp, Christian; Geiger, Otto; Martínez Romero, Esperanza; Werner, Dietrich; Vinuesa, Pablo
Rhizobium tropici CIAT899 is highly tolerant to several environmental stresses and is a good competitor for nodule occupancy of common bean plants in acid soils. Random transposon mutagenesis was performed to identify novel genes of this strain involved in symbiosis and stress tolerance. Here, we present a genetic analysis of the locus disrupted by the Tn5 insertion in mutant 899-PV9, which lead to the discovery of sycA, a homolog of the ClC family of chloride channels and Cl-/H+ exchange transporters. A nonpolar deletion in this gene caused serious deficiencies in nodule development, nodulation competitiveness, and N2 fixation on Phaseolus vulgaris plants, probably due to its reduced ability to invade plant cells and to form stable symbiosomes, as judged by electron transmission microscopy. A second gene (olsC), found downstream of sycA, is homologous to aspartyl/asparaginyl β-hydroxylases and modifies two species of ornithine-containing lipids in vivo, presumably by hydroxylation at a still-unknown position. A mutant carrying a nonpolar deletion in olsC is symbiotically defective, whereas overexpressed OlsC in the complemented strain provokes an acid-sensitive phenotype. This is the first report of a ClC homolog being essential for the establishment of a fully developed N2-fixing root nodule symbiosis and of a putative β-hydroxylase that modifies ornithine-containing membrane lipids of R. tropici CIAT899, which, in turn, are contributing to symbiotic performance and acid tolerance.
A Comparison of four Methods to Evaluate the Butterfly Abundance. Using a Tropical Community
(Journal of the Lepidopterists' Society 45(3), 1991, 241-243, 1991-03-18) Monge Nájera, Julián; Nielsen Muñoz, Vanessa
In recent years. several transect methods to evaluate the abundance of butterflies have been proposed (Pollard, E. 1977, Biol. Conserv. 12:115—134; Feltwell, 3. 1982. Proc. Trans. Br. Entomol. Nat. Hist. Soc. 15:17—24). but to our knowledge there has been no attempt to compare experimentally their usefulness in relation to the availability of time and resources. Herein, we present the results of an experiment in which modifications of four of those methods were applied, simultaneously, to a community of neotropical butterflies
A comparison of Monstera deliciosa and M. tacanaensis, with comments on Monstera section Tornelia (Araceae)
(2020) Cedeño Fonseca, Marco Vinicio; Díaz Jiménez, Pedro; Zuluaga Trochez, Alejandro; Blanco Coto, Mario Alberto
Monstera deliciosa, one of the most commonly cultivated aroids, is a morphologically variable species and has traditionally been considered native to southern Mexico, Guatemala, Costa Rica and Panama. We demonstrate that M. tacanaensis, which naturally occurs in those four countries and has been considered a synonym of M. deliciosa, is a closely related but different species. The natural range of M. deliciosa is restricted to southern Mexico and Guatemala. The name M. borsigiana is a synonym of M. deliciosa, representing one of its variations. The name Tornelia fragrans (another synonym of M. deliciosa) is lectotypified. A taxonomic history of Monstera section Tornelia (of which both M. deliciosa and M. tacanaensis are members) is presented; we also include M. maderaverde of Honduras in this section. Detailed descriptions and illustrations of M. deliciosa and M. tacanaensis are provided. The seeds of M. tacanaensis are extruded from the fruit at maturity, a phenomenon first reported here for the genus.
A correction to the Lepanthes guatemalensis group (Orchidaceae: Pleurothallidinae) in Costa Rica, with a new species
(2021) Pupulin, Franco
The true Lepanthes edwardsii is first recorded for the flora of Costa Rica, described and illustrated on the basis of a Costa Rican voucher. The taxon previously recorded under that name is described as new to science as Lepanthes bogariniana; it is closely related to L. edwardsii, L. durikäensis, and L. viquezii, but can be distinguished by the narrowly elliptic lateral sepals, the tails straight to curved inward, the lobes of the petals with rounded apices, the blades of the lip straight and not bent towards the lateral sepals, and the yellowish-white column.
A decade of submersible observations revealed temporal trends in elasmobranchs in a remote island of the Eastern Tropical Pacific Ocean
(2024) Espinoza Mendiola, Mario; Quesada Pérez, Fabio; Madrigal Mora, Sergio; Naranjo Elizondo, Beatriz; Clarke, Tayler McLellan; Cortes Núñez, Jorge
No-take marine protected areas (MPAs) can mitigate the effects of overfishing, climate change and habitat degradation, which are leading causes of an unprecedented global biodiversity crisis. However, assessing the effectiveness of MPAs, especially in remote oceanic islands, can be logistically challenging and often restricted to relatively shallow and accessible environments. Here, we used a long-term dataset (2010-2019) collected by the DeepSee submersible of the Undersea Hunter Group that operates in Isla del Coco National Park, Costa Rica, to (1) determine the frequency of occurrence of elasmobranch species at two depth intervals (50-100 m; 300-400 m), and (2) investigate temporal trends in the occurrence of common elasmobranch species between 2010 and 2019, as well as potential drivers of the observed changes. Overall, we observed 17 elasmobranch species, 15 of which were recorded on shallow dives (50-100 m) and 11 on deep dives (300-400 m). We found a decreasing trend in the probability of occurrence of Carcharhinus falciformis over time (2010-2019), while other species (e.g. Taeniurops meyeni, Sphyrna lewini, Carcharhinus galapagensis, Triaenodon obesus, and Galeocerdo cuvier) showed an increasing trend. Our study suggests that some species like S. lewini may be shifting their distributions towards deeper waters in response to ocean warming but may also be sensitive to low oxygen levels at greater depths. These findings highlight the need for regional 3D environmental information and long-term deepwater surveys to understand the extent of shark and ray population declines in the ETP and other regions, as most fishery-independent surveys from data-poor countries have been limited to relatively shallow waters.
A distinctive oral phenotype points to FAM20A mutations not identified by Sanger sequencing
(2015-10-04) Poulter, James A.; Smith, Claire E. L.; Murillo Knudsen, Gina; Silva de la Fuente, Sandra Maria; Feather, Sally; Howell Ramírez, Marianella; Crinnion, Laura; Bonthron, David; Carr, Ian M.; Watson, Christopher M.; Inglehearn, Chris F.; Mighell, Alan J.
Biallelic FAM20A mutations cause two conditions where Amelogenesis Imperfecta (AI) is the presenting feature: Amelogenesis Imperfecta and Gingival Fibromatosis Syndrome; and Enamel Renal Syndrome. A distinctive oral phenotype is shared in both conditions. On Sanger sequencing of FAM20A in cases with that phenotype, we identified two probands with single, likely pathogenic heterozygous mutations. Given the recessive inheritance pattern seen inall previous FAM20A mutation-positive families and the potential for renal disease, further screening was carried out to look for a second pathogenic allele. Reverse transcriptase-PCR on cDNA was used to determine transcript levels. CNVseq was used to screen for genomic insertions and deletions. In one family, FAM20AcDNA screening revealed only a single mutated FAM20A allele with the wild-type allele not transcribed. In the second family, CNV detection by whole genome sequencing (CNVseq) revealed a heterozygous 54.7 kb duplication encompassing exons 1 to 4 of FAM20A. This study confirms the link between biallelic FAM20A mutations and the characteristic oral phenotype. It highlights for the first time examples of FAM20A mutations missed by the most commonly used mutation screening techniques. This information informed renal assessment and ongoing clinical care.
A genome‐wide quantitative trait locus (QTL) linkage scan of NEO personality factors in Latino families segregating bipolar disorder
(2017) Dae Lee, Byung; González, Suzanne; Villa, Erika; Camarillo, Cynthia; Rodriguez, Marco; Shugart, Yin Yao; Guo, Wei; Flores, Deborah; Jerez, Álvaro; Raventós Vorst, Henriette; Ontiveros Sánchez de la Barquera, Jose Alfonso; Nicolini Sánchez, José Humberto; Escamilla, Michael
Personality traits have been suggested as potential endophenotypes for Bipolar Disorder (BP), as they can be quantitatively measured and show correlations with BP. The present study utilized data from 2,745 individuals from 686 extended pedigrees originally ascertained for having multiplex cases of BP (963 cases of BPI or schizoaffective BP). Subjects were assessed with the NEO Personality Inventory, Revised (NEO PI‐R) and genotyped using the Illumina HumanLinkage‐24 Bead Chip, with an average genetic coverage of 0.67 cM. Two point linkage scores were calculated for each trait as a quantitative variable using SOLAR (Sequential Oligogenic Linkage Analysis Routines). Suggestive evidence for linkage was found for neuroticism at 1q32.1 (LOD = 2.52), 6q23.3 (2.32), 16p12 (2.79), extraversion at 4p15.3 (2.33), agreeableness at 4q31.1 (2.37), 5q34 (2.80), 7q31.1 (2.56), 16q22 (2.52), and conscientiousness at 4q31.1 (2.50). Each of the above traits have been shown to be correlated with the broad BP phenotype in this same sample. In addition, for the trait of openness, we found significant evidence of linkage to chromosome 3p24.3 (rs336610, LOD = 4.75) and suggestive evidence at 1q43 (2.74), 5q35.1 (3.03), 11q14.3 (2.61), 11q21 (2.30), and 19q13.1 (2.52). These findings support previous linkage findings of the openness trait to chromosome 19q13 and the agreeableness trait to 4q31 and identify a number of new loci for personality endophenotypes related to bipolar disorder.
A High-Throughput Screen Identifies a New Natural Product with Broad-Spectrum Antibacterial Activity
(2012) Ymele Leki, Patrick; Cao, Shugeng; Sharp, Jared ; Lambert, Kathleen G.; McAdam, Alexander J.; Husson, Robert N.; Tamayo Castillo, Giselle ; Clardy, Jon; Watnick, Paula I.
Due to the inexorable invasion of our hospitals and communities by drug-resistant bacteria, there is a pressing need for novel antibacterial agents. Here we report the development of a sensitive and robust but low-tech and inexpensive high-throughput metabolic screen for novel antibiotics. This screen is based on a colorimetric assay of pH that identifies inhibitors of bacterial sugar fermentation. After validation of the method, we screened over 39,000 crude extracts derived from organisms that grow in the diverse ecosystems of Costa Rica and identified 49 with reproducible antibacterial effects. An extract from an endophytic fungus was further characterized, and this led to the discovery of three novel natural products. One of these, which we named mirandamycin, has broad-spectrum antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Vibrio cholerae, methicillin-resistant Staphylococcus aureus, and Mycobacterium tuberculosis. This demonstrates the power of simple high throughput screens for rapid identification of new antibacterial agents from environmental samples.
A highly threatened new species of Vanilla from Costa Rica
(2018) Karremans Lok, Adam Philip; Lehmann, Patricia
A new species of Vanilla is described and illustrated from the southeastern tip of Costa Rica, close to the border with Panama. Vanilla karenchristianae was found in a region of the country that has no protected areas and very little original forest cover. The unexpected discovery highlights the importance of continued and sustainable conservation efforts across all life zones and ecoregions, underlining the importance of the public sector in biodiversity research and protection. The new species belongs to subgenus Xanata, which includes all the fragrant Vanilla species used in commerce. Vanilla karenchristianae is easily distinguished from all other Central American species by the combination of very narrow leaves, with a recurved apex, the green-and-white flowers and the appendages on the lip, a feature found otherwise only in the closely related Vanilla helleri, Vanilla insignis and Vanilla odorata.
A Historical Review of the Artificial Pollination of Vanilla planifolia: The Importance of Collaborative Research in a Changing World
(2024-11-01) Karremans Lok, Adam Philip
The natural fertilization of Vanilla planifolia has long been a matter of speculation. Stingless (tribe Meliponini) and orchid bees (tribe Euglossini) are often cited as effective pollinators, but direct evidence is notoriously lacking. As with other food-deceptive orchids, the natural fruit-set in V. planifolia is low and does not occur spontaneously outside its native range in Middle America. Fruiting has, therefore, necessitated human intervention through artificial pollination. How Vanilla first came to be artificially pollinated is a controversial issue spurring egotism and nationalism. There are numerous texts offering differing versions of the historical events that led to the discov-ery of the artificial fertilization of V. planifolia and its propagation as a crop. Historical records show Vanilla was simultaneously being pollinated in several parts of the world. I argue that the suspected independent simultaneous discoveries made in Liège, Paris, Padua, the Dutch colony of Java (Indonesia), and the French insular colonies Réunion (Bourbon), Guadeloupe, and Martinique are not unconnected. I conclude that they can be traced back to a single discoverer whose feat was spread around the globe by a tight network of corresponding naturalists. This view contrasts with previous authors. Finally, current concerns regarding Vanilla pollination and production are ad-dressed, highlighting the need for immediate actions to conserve the genetic diversity of the crop’s wild relatives to attenuate the effect of extreme climates in a changing world. A plea is made to shift the focus to Middle America, stimulating and supporting local research and conservation efforts and the allocation of funds from this billion-dollar industry.
A just overtime discovery: another new species of Echinosepala (Orchidaceae) from Costa Rica
(2022-08-13) Pupulin, Franco; Álvarez Alcázar, Leonardo; Bogarín Chaves, Diego Gerardo
Echinosepala truncata is described as new to science and illustrated from the holotype. It is compared with E. tomentosa, from which it differs by the sparsely lanate ovary, the narrowly obovate, apically rounded synsepal, the spathulate, apically and basally rounded petals, and the rectangular, apically truncate lip. The phylogenetic relationships of the new species could be hypothesized based on a shared set of morphological characters and geographic distribution.
A Mesoamerican origin of cherimoya (Annona cherimola Mill.): Implications for the conservation of plant genetic resources
(2017) Larranaga González, Nerea; Albertazzi Castro, Federico José; Fontecha Sandoval, Gustavo Adolfo; Palmieri Santisteban, Margarita; Rainer, Heimo; van Zonneveld, Maarten; Hormaza Urroz, Iñaki
Knowledge on the structure and distribution of genetic diversity is a key aspect to plan and execute an efficient conservation and utilization of the genetic resources of any crop as well as for determining historical demographic inferences. In this work, a large data set of 1,765 accessions of cherimoya (Annona cherimola Mill, Annonaceae), an underutilized fruit tree crop native to the Neotropics and used as a food source by pre‐Columbian cultures, was collected from six different countries across the American continent and amplified with nine highly informative microsatellite markers. The structure analyses, fine representation of the genetic diversity and an ABC approach suggest a Mesoamerican origin of the crop, contrary to previous reports, with clear implications for the dispersion of plant germplasm between Central and South America in pre‐Columbian times. These results together with the potential distribution of the species in a climatic change context using two different climate models provide new insights for the history and conservation of extant genetic resources of cherimoya that can be applied to other currently underutilized woody perennial crops.
A metabolomic platform to identify and quantify polyphenols in coffee and related species using liquid chromatography mass spectrometry
(2023) Castro Moretti, Fernanda R.; Cocuron, Jean Christophe; Castillo González, Humberto; Escudero Leyva, Efraín; Chaverri Echandi, Priscila; Guerreiro Filho, Oliveiro; Slot, Jason C.; Alonso, Ana Paula
Introduction: Products of plant secondary metabolism, such as phenolic compounds, flavonoids, alkaloids, and hormones, play an important role in plant growth, development, stress resistance. The plant family Rubiaceae is extremely diverse and abundant in Central America and contains several economically important genera, e.g. Coffea and other medicinal plants. These are known for the production of bioactive polyphenols (e.g. caffeine and quinine), which have had major impacts on human society. The overall goal of this study was to develop a high-throughput workflow to identify and quantify plant polyphenols. Methods: First, a method was optimized to extract over 40 families of phytochemicals. Then, a high-throughput metabolomic platform has been developed to identify and quantify 184 polyphenols in 15 min. Results: The current metabolomics study of secondary metabolites was conducted on leaves from one commercial coffee variety and two wild species that also belong to the Rubiaceae family. Global profiling was performed using liquid chromatography high-resolution time-of-flight mass spectrometry. Features whose abundance was significantly different between coffee species were discriminated using statistical analysis and annotated using spectral databases. The identified features were validated by commercially available standards using our newly developed liquid chromatography tandem mass spectrometry method. Discussion: Caffeine, trigonelline and theobromine were highly abundant in coffee leaves, as expected. Interestingly, wild Rubiaceae leaves had a higher diversity of phytochemicals in comparison to commercial coffee: defenserelated molecules, such as phenylpropanoids (e.g., cinnamic acid), the terpenoid gibberellic acid, and the monolignol sinapaldehyde were found more abundantly in wild Rubiaceae leaves.
A methane sink in the Central American high elevation páramo: Topographic, soil moisture and vegetation effects
(2020) Chai, Leanne L.; Hernandez Ramirez, Guillermo; Hik, David S.; Barrio, Isabel C.; Frost, Carol M.; Chinchilla Soto, Isabel Cristina; Esquivel Hernández, Germain
Methane (CH4) is a strong greenhouse gas with a global warming potential 23 times larger than that of carbon dioxide. Characterizing ecosystems as either sources or sinks for methane and their magnitudes informs on biosphere contributions to the global CH4 budget and to warming of the atmosphere. We quantified methane fluxes for the first time in a neotropical alpine páramo (Valle de Los Conejos, Chirripó Massif, Costa Rica) and examined the relationships of these fluxes with topography, soil moisture and vegetation, during the transition from dry to rainy season. Using closed chambers and laser spectroscopy, we measured soil CH4 and CO2 fluxes across a field site encompassing: a grassy plain as well as a plain, a gentle slope and a plateau dominated by a dwarf bamboo (Chusquea subtessellata Hitchcock). We found that the páramo landscape acts as a sink for CH4 [−53.1 ± 29.6 (mean ± SE) µg C m−2 hr−1]. Of the four field areas, the grassy plain was on average the strongest CH4 sink, likely because this soil profile had no drainage restrictions and was well aerated. By contrast, in the slope and plateau, a heavily-consolidated subsurface layer was shown to perch water, increasing surface soil moisture and limiting CH4 uptake. Conversely, in certain parts of the plain, where Chusquea grew vigorously in discrete, tall patches, we found intense CH4 uptake beneath these patches. Within the Chusquea plain, these hot spots of CH4 uptake localized under the tall Chusquea had double the uptake rates than outside these patches, with even greater uptake than the average in the grassy plain. Our results show that CH4 uptake in the páramo is driven by moisture interacting with impeding soil layers, vegetation and topography.

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