RESUMO
Plant microbiomes are known to serve several important functions for their host, and it is therefore important to understand their composition as well as the factors that may influence these microbial communities. The microbiome of Thalassia testudinum has only recently been explored, and studies to-date have primarily focused on characterizing the microbiome of plants in a single region. Here, we present the first characterization of the composition of the microbial communities of T. testudinum across a wide geographical range spanning three distinct regions with varying physicochemical conditions. We collected samples of leaves, roots, sediment, and water from six sites throughout the Atlantic Ocean, Caribbean Sea, and the Gulf of Mexico. We then analyzed these samples using 16S rRNA amplicon sequencing. We found that site and region can influence the microbial communities of T. testudinum, while maintaining a plant-associated core microbiome. A comprehensive comparison of available microbial community data from T. testudinum studies determined a core microbiome composed of 14 ASVs that consisted mostly of the family Rhodobacteraceae. The most abundant genera in the microbial communities included organisms with possible plant-beneficial functions, like plant-growth promoting taxa, disease suppressing taxa, and nitrogen fixers.
RESUMO
Background: Seagrass meadows, known for providing essential ecosystem services like supporting fishing, coastline protection from erosion, and acting as carbon sinks to mitigate climate change effects, are facing severe degradation. The current deteriorating state can be attributed to the combination of anthropogenic activities, biological factors (i.e., invasive species), and natural forces (i.e., hurricanes). Indeed, the global seagrass cover is diminishing at an alarming mean rate of 7% annually, jeopardizing the health of these vital ecosystems. However, in the Island Municipality of Culebra, Puerto Rico, losses are occurring at a faster pace. For instance, hurricanes have caused over 10% of cover seagrass losses, and the natural recovery of seagrasses across Culebra's coast has been slow due to the low growth rates of native seagrasses (Thalassia testudinum and Syringodium filiforme) and the invasion of the invasive species Halophila stipulacea. Restoration programs are, thus, necessary to revitalize the native seagrass communities and associated fauna while limiting the spread of the invasive species. Methods: Here, we present the results of a seagrass meadow restoration project carried out in Punta Melones (PTM), Culebra, Puerto Rico, in response to the impact of Hurricanes Irma and María during 2017. The restoration technique used was planting propagation units (PUs), each with an area of 900 cm2 of native seagrasses Thalassia testudinum and Syringodium filiforme, planted at a depth between 3.5 and 4.5 m. A total of 688 PUs were planted between August 2021 and August 2023, and a sub-sample of 88 PUs was monitored between August 2021 and April 2023. Results: PUs showed over 95% of the seagrass survived, with Hurricane Fiona causing most of the mortalities potentially due to PUs burial by sediment movement and uplifting by wave energy. The surface area of the planting units increased by approximately 200% (i.e., 2,459 cm2), while seagrass shoot density increased by 168% (i.e., 126 shoots by PU). Additionally, flowering and fruiting were observed in multiple planting units, indicating 1) that the action taken did not adversely affect the PUs units and 2) that the project was successful in revitalizing seagrass populations. The seagrass restoration project achieved remarkable success, primarily attributed to the substantial volume of each PUs. Likely this high volume played a crucial role in facilitating the connection among roots, shoots, and microfauna while providing a higher number of undamaged and active rhizome meristems and short shoots. These factors collectively contributed to the enhanced growth and survivorship of the PUs, ultimately leading to the favorable outcome observed in the seagrass restoration project.
Assuntos
Alismatales , Brugmansia , Hydrocharitaceae , Ecossistema , Efeitos Antropogênicos , SupuraçãoRESUMO
Understanding how megaherbivores incorporate habitat features into their foraging behavior is key toward understanding how herbivores shape the surrounding landscape. While the role of habitat structure has been studied within the context of predator-prey dynamics and grazing behavior in terrestrial systems, there is a limited understanding of how structure influences megaherbivore grazing in marine ecosystems. To investigate the response of megaherbivores (green turtles) to habitat features, we experimentally introduced structure at two spatial scales in a shallow seagrass meadow in The Bahamas. Turtle density increased 50-fold (to 311 turtles ha-1 ) in response to the structures, and turtles were mainly grazing and resting (low vigilance behavior). This resulted in a grazing patch exceeding the size of the experimental setup (242 m2 ), with reduced seagrass shoot density and aboveground biomass. After structure removal, turtle density decreased and vigilance increased (more browsing and shorter surfacing times), while seagrass within the patch partly recovered. Even at a small scale (9 m2 ), artificial structures altered turtle grazing behavior, resulting in grazing patches in 60% of the plots. Our results demonstrate that marine megaherbivores select habitat features as foraging sites, likely to be a predator refuge, resulting in heterogeneity in seagrass bed structure at the landscape scale.
Assuntos
Ecossistema , Tartarugas , Animais , Tartarugas/fisiologia , Biomassa , Herbivoria , BahamasRESUMO
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can increase the value of seagrass beds as habitat for nekton via added food resources and structural complexity. But, as algal biomass increases, it can also decrease light availability, inhibit faunal movements, smother benthic communities, and contribute to hypoxia, all of which can reduce nekton abundance. We quantified the abundance and distribution of drift macroalgae within seagrass meadows dominated by turtle grass Thalassia testudinum across the northern Gulf of Mexico and compared seagrass characteristics to macroalgal biomass and distribution. Drift macroalgae were most abundant in areas with higher seagrass shoot densities and intermediate canopy heights. We did not find significant relationships between algal biomass and point measures of salinity, temperature, or depth. The macroalgal genera Laurencia and Gracilaria were present across the study region, Agardhiella and Digenia were collected in the western Gulf of Mexico, and Acanthophora was collected in the eastern Gulf of Mexico. Our survey revealed drift algae to be abundant and widespread throughout seagrass meadows in the northern Gulf of Mexico, which likely influences the habitat value of seagrass ecosystems.
Assuntos
Hydrocharitaceae , Alga Marinha , Ecossistema , Golfo do México , BiomassaRESUMO
Seagrass meadows are valued coastal habitats that provide ecological and economic benefits around the world. Despite their importance, many meadows are in decline, driven by a variety of anthropogenic impacts. While these declines have been well documented in some regions, other locations (particularly within the tropics) lack long-term monitoring programs needed to resolve seagrass trends over time. Effective and spatially-expansive monitoring within under-represented regions is critical to provide an accurate perspective on seagrass status and trends. We present a comprehensive dataset on seagrass coverage and composition across 24 sites in Bahía Almirante, a lagoon along the Caribbean coast of Panama. Using a single survey, we focus on capturing spatial variation in seagrass physical and elemental characteristics and provide data on key seagrass bio-indicators, such as leaf morphology (length and width), elemental content (% nitrogen and phosphorus) and stable isotopic signatures (δ 13C and δ 15N). We further explore relationships between these variables and water depth (proxy for light availability) and proximity to shore (proxy for terrestrial inputs). The seagrass assemblage was mostly monospecific (dominated by Thalassia testudinum) and restricted to shallow water (<3 m). Above-ground biomass varied widely, averaging 71.7 g dry mass m-2, yet ranging from 24.8 to 139.6 g dry mass m-2. Leaf nitrogen content averaged 2.2%, ranging from 1.76 to 2.57%, while phosphorus content averaged 0.19% and ranged from 0.15 to 0.23%. These values were high compared to other published reports for T. testudinum, indicating elevated nutrient availability within the lagoon. Seagrass stable isotopic characteristics varied slightly and were comparable with other published values. Leaf carbon signatures (δ 13C) ranged from -11.74 to -6.70 and were positively correlated to shoreline proximity, suggesting a contribution of terrestrial carbon to seagrass biomass. Leaf nitrogen signatures (δ 15N) ranged from -1.75 to 3.15 and showed no correlation with shoreline proximity, suggesting that N sources within the bay were not dominated by localized point-source discharge of treated sewage. Correlations between other seagrass bio-indicators and environmental metrics were mixed: seagrass cover declined with depth, while biomass was negatively correlated with N, indicating that light and nutrient availability may jointly regulate seagrass cover and biomass. Our work documents the response of seagrass in Bahía Almirante to light and nutrient availability and highlights the eutrophic status of this bay. Using the broad spatial coverage of our survey as a baseline, we suggest the future implementation of a continuous and spatially expansive seagrass monitoring program within this region to assess the health of these important systems subject to global and local stressors.
RESUMO
The Caribbean white sea urchin, L. variegatus, is locally harvested in Margarita Island and other locations of southeastern Venezuela. The recent reduction of densities raises concerns about potential impacts for overfishing. Densities of L. variegatus were estimated at Impact and Control locations between late-2012 and mid-2015 to 1) test temporal changes, comparing with 1997-1998 estimations, 2) the effect of seasonal closure on resource recovery and 3) the effect of local expansion. The results suggest that, after a period of fourteen years, an important decrease in L. variegatus densities occurred, as well as a lack of population recovery in fishing areas during seasonal closures. Furthermore, during the monitoring program, it was observed fishing activities in one Control location that subsequently showed clear patterns of population depletion, like other Impact locations. Fishing impact on L. variegatus populations is severe, persistent and expands over time without evidence of recovery, therefore it is expected that local populations of L. variegatus would collapse under current exploitation levels. However, due to the L. variegatus life history and its distribution range, recovery of impacted populations could be possible via recruitment of planktonic larvae if effective management actions are imposed. It is recommended to exercise more regulations on fishing activities and to execute management measures that allow recovering the stocks to maintain local populations of sea urchin.
Assuntos
Conservação dos Recursos Naturais , Lytechinus , Animais , Região do Caribe , Pesqueiros , Ilhas , Ouriços-do-Mar , VenezuelaRESUMO
Marine plants have become an inexhaustible reservoir of new phytopharmaceuticals for cancer treatment. We demonstrate in vitro/in vivo antitumor efficacy of a standardized polyphenol extract from the marine angiosperm Thalassia testudinum (TTE) in colon tumor cell lines (RKO, SW480, and CT26) and a syngeneic allograft murine colorectal cancer model. MTT assays revealed a dose-dependent decrease of cell viability of RKO, CT26, and SW480 cells upon TTE treatment with IC50 values of, respectively, 175, 115, and 60 µg/mL. Furthermore, TTE significantly prevented basal and bFGF-induced angiogenesis in the chicken chorioallantoic membrane angiogenesis assay. In addition, TTE suppressed bFGF-induced migration of endothelial cells in a wound closure assay. Finally, TTE treatment abrogated CT26 colorectal cancer growth and increased overall organism survival in a syngeneic murine allograft model. Corresponding transcriptome profiling and pathway analysis allowed for the identification of the mechanism of action for the antitumor effects of TTE. In line with our in vitro/in vivo results, TTE treatment triggers ATF4-P53-NFκB specific gene expression and autophagy stress pathways. This results in suppression of colon cancer cell growth, cell motility, and angiogenesis pathways in vitro and in addition promotes antitumor immunogenic cell death in vivo.
Assuntos
Antineoplásicos Fitogênicos/uso terapêutico , Movimento Celular/efeitos dos fármacos , Neoplasias Colorretais/patologia , Hydrocharitaceae , Morte Celular Imunogênica/efeitos dos fármacos , Neovascularização Patológica/patologia , Extratos Vegetais/uso terapêutico , Animais , Antineoplásicos Fitogênicos/isolamento & purificação , Antineoplásicos Fitogênicos/farmacologia , Autofagia/efeitos dos fármacos , Autofagia/fisiologia , Linhagem Celular Tumoral , Movimento Celular/fisiologia , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/metabolismo , Humanos , Hydrocharitaceae/química , Morte Celular Imunogênica/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Neovascularização Patológica/tratamento farmacológico , Neovascularização Patológica/metabolismo , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Ensaios Antitumorais Modelo de Xenoenxerto/métodosRESUMO
The aim of the present work was to evaluate the effects of Thalassia testudinum hydroethanolic extract, its polyphenolic fraction and thalassiolin B on the activity of phase I metabolizing enzymes as well as their antimutagenic effects. Spectrofluorometric techniques were used to evaluate the effect of tested products on rat and human CYP1A and CYP2B activity. The antimutagenic effect of tested products was evaluated in benzo[a]pyrene (BP)-induced mutagenicity assay by an Ames test. Finally, the antimutagenic effect of Thalassia testudinum (100 mg/kg) was assessed in BP-induced mutagenesis in mice. The tested products significantly (p < 0.05) inhibit rat CYP1A1 activity, acting as mixed-type inhibitors of rat CYP1A1 (Ki = 54.16 ± 9.09 µg/mL, 5.96 ± 1.55 µg/mL and 3.05 ± 0.89 µg/mL, respectively). Inhibition of human CYP1A1 was also observed (Ki = 197.1 ± 63.40 µg/mL and 203.10 ± 17.29 µg/mL for the polyphenolic fraction and for thalassiolin B, respectively). In addition, the evaluated products significantly inhibit (p < 0.05) BP-induced mutagenicity in vitro. Furthermore, oral doses of Thalassia testudinum (100 mg/kg) significantly reduced (p < 0.05) the BP-induced micronuclei and oxidative damage, together with an increase of reduced glutathione, in mice. In summary, Thalassia testudinum metabolites exhibit antigenotoxic activity mediated, at least, by the inhibition of CYP1A1-mediated BP biotransformation, arresting the oxidative and mutagenic damage. Thus, the metabolites of T. testudinum may represent a potential source of chemopreventive compounds for the adjuvant therapy of cancer.
Assuntos
Antimutagênicos/farmacologia , Benzo(a)pireno/toxicidade , Citocromo P-450 CYP1A1/antagonistas & inibidores , Inibidores das Enzimas do Citocromo P-450/farmacologia , Flavonoides/farmacologia , Hydrocharitaceae/metabolismo , Polifenóis/farmacologia , Salmonella typhi/efeitos dos fármacos , Ativação Metabólica , Animais , Antimutagênicos/isolamento & purificação , Benzo(a)pireno/metabolismo , Citocromo P-450 CYP1A1/metabolismo , Citocromo P-450 CYP1A2/metabolismo , Inibidores do Citocromo P-450 CYP1A2/isolamento & purificação , Inibidores do Citocromo P-450 CYP1A2/farmacologia , Inibidores das Enzimas do Citocromo P-450/isolamento & purificação , Dano ao DNA/efeitos dos fármacos , Flavonoides/isolamento & purificação , Humanos , Isoenzimas , Cinética , Micronúcleos com Defeito Cromossômico/induzido quimicamente , Testes para Micronúcleos , Estresse Oxidativo/efeitos dos fármacos , Polifenóis/isolamento & purificação , Ratos , Salmonella typhi/genéticaRESUMO
RESUMEN Thalassia testudinum es la planta marina de mayor abundancia en el litoral de La Habana y del Caribe en general, conocida comúnmente como praderas submarinas o hierba de tortuga. Entre los compuestos de interés que se pueden encontrar en esta especie sobresalen los polifenoles, los cuales son componentes estructurales de su pared celular y poseen propiedades funcionales y bioactivas como antioxidante, anti-inflamatorio, neuroprotector y hepatoprotector. Investigaciones previas evaluaron diversos métodos de extracción de compuestos bioactivos para esta especie, por lo que este trabajo tuvo como objetivo optimizar las condiciones de extracción del contenido de polifenoles totales. Para ello se utilizó el método de Box y Hunter y se evaluó el efecto de tres factores influyentes en la extracción de compuestos fenólicos (velocidad de agitación, relación material vegetal/% alcohol y concentración de etanol). Como variable respuesta se empleó el contenido de polifenoles totales determinada por el método de Folin-Ciocalteu. Los resultados del diseño proporcionaron como condiciones óptimas en las variables estudiadas las siguientes: 1/11.5 p:v, 60% de EtOH y 800 r.p.m., alcanzando rendimiento de polifenoles totales, igual a 25.60 mg/g de extracto seco; superior a las restantes condiciones de extracción para un extracto bioactivo con potencialidades de uso en la industria farmacéutica o nutracéutica.
ABSTRACT Thalassia testudinum is the marine plant of greatest abundance along the coast of Havana and the Caribbean in general, commonly known as seagrass meadows or turtle grass. Among the compounds of interest that can be found in this species there are polyphenols, which are structural components of its cell wall and have functional and bioactive properties such as antioxidant, anti-inflammatory, neuroprotective and hepatoprotective. Previous research evaluated different methods of extracting bioactive compounds from this species, and this work aimed to optimize the extraction conditions of the total polyphenol content. For this, the Box and Hunter method was used and the effect of three influential factors in the extraction of phenolic compounds (agitation speed, vegetal material / solvent ratio and ethanol concentration) was evaluated. The total polyphenol content determined by the Folin-Ciocalteu method was used as a response variable. The design results provided as optimal conditions in the studied variables the following: 1/11.5 w: v, 60% EtOH and 800 r.p.m., reaching a total polyphenol yield of 25.60 mg/g of dry extract; which contributes to the obtaining of a better content of total phenols in a bioactive extract with potentialities of use in the pharmaceutical or nutraceutical industries.
RESUMO
Seagrasses are among the most productive shallow water ecosystems, serving a diverse assemblage of fish and invertebrates. Tropical seagrass communities are dominated by the turtle grass Thalassia testudinum, whose wide, flattened blades host diverse epibiont communities. Amidst its epibionts, T. testudinum may also be accumulating microplastics, which are a ubiquitous marine pollutant even in remote locales. To assess the extent of microplastic accumulation, seagrass samples were collected from Turneffe Atoll, which lies offshore but parallel with a major urban center. Seventy-five percent of Thalassia blades had encrusted microplastics, with microfibers occurring more than microbeads and chips by a ratio of 59:14. Grazers consumed seagrasses with higher densities of epibionts. Potential mechanisms for microplastic accumulation include entrapment by epibionts, or attachment via biofilms. This study is the first to document microplastics on marine vascular plants, suggesting that macroherbivory is a viable pathway for microplastic pollution to enter marine food webs.