Antioxidant activities in tropical marine macroalgae from the Yucatan Peninsula,Mexico

Extracts from 48 marine macroalgae species (17 Chlorophyta, 8 Phaeophyta and 23 Rhodophyta) from the coasts of Yucatan and Quintana Roo (Mexico) were evaluated for antioxidant activity. The antioxidant activity was measured with the DPPH (2,2-diphenyl-1-picrylhydrasyl) method, and the phenolic content of each extract were also evaluated. All species exhibited a DPPH radical scavenging activity, and three species (Avrainvillea longicaulis, Chondria baileyana and Lobophora variegata) demonstrated great antioxidant potential with very low oxidation index EC₅₀ (1.44 ± 0.01, 2.84 ± 0.07 and 0.32 ± 0.01 mg mL⁻¹, respectively), significantly equivalent to EC₅₀ of some commercial antioxidants such as α-tocopherol, ascorbic acid, BHA and BHT. Moreover, extracts of the most active species exhibited reducing activities, superoxide anion radical scavenging and inhibition of lipid peroxidation. These results suggest that some macroalgae from the Yucatan peninsula have a great antioxidant potential which could be considered for future applications in medicine, food production or cosmetic industry.     

Historical biogeography of the Yucatan Peninsula,Mexico: a perspective from ferns (Monilophyta) and lycopods (Lycophyta)

Based on known data sets and maximum entropy distribution data of fern and lycopod species registered in the Yucatán Peninsula, track and parsimony analyses were undertaken to evaluate the contribution of these groups to the establishment of biogeographical relationships of the peninsula with other areas. The resulting generalized tracks clearly agree with the geological origin of the peninsula and the previously recognized relationship with the Greater Antilles is not supported for ferns and lycopods. Instead, a Central American generalized track connects the Yucatán Peninsula with south‐eastern México and Central America. Floristically, the peninsula harbours 66 species of ferns and lycopods. Seven are registered for the first time in the Yucatán Peninsula and one is a new species for México. These species do not follow the latitudinal pattern expected if ecological factors, such as humidity and rainfall, were the most important in determining their distributions. Groups of areas recognized with parsimony analysis of endemicity could not be defined as provinces as a result of the lack of endemic species. Nevertheless, a regionalization scheme based on maximum entropy distribution data and supported by track analyses is proposed. Two separate districts are recognized within the Yucatán Peninsula: arid/dry Yucatán in the north and El Petén (humid) in the south. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98 , 775–786.     

Hat weaving withJipi, Carludovica Palmata (Cyclanthaceae) in the Yucatan Peninsula, Mexico

Weaving hats withjipi,Carludovica palmata (Cyclanthaceae) has built the local economy and cultural identity for the people of Becal, in the Yucatán Peninsula, Mexico. They obtain most material from cultivated sources, weave in man-made caves, and market the goods to commercial centers. BecauseJipi does not appear to deplete the soil, they do not need to clear more land for sustainable production. Although weaving traditionally served as the main source of income and social activity in Becal, interest in weaving is declining as the town modernizes. Although profits gained from weaving add to family earnings, because of the many hands through which the hat passes, this income remains low compared to the final selling prices. Thus, many who have the opportunity to pursue other careers are doing so. However, for rural communities, without other earning options, weaving may provide an economically and environmentally advantageous way to use the land.     

Metazoan parasite infracommunities of Florida pompano (Trachinotus carolinus) from the coast of the Yucatan Peninsula,Mexico

Metazoan parasite infracommunities of the Florida pompano (Trachinotus carolinus) were studied in terms of species composition, species richness, diversity, numerical dominance, and similarity. Seventy-five fishes were collected from 4 localities along the Yucatan Peninsula coast and 24 parasite species recovered. Most were digeneans (8 species) and nematodes (7). Other species were monogeneans (3). aspidogastreans (2), cestodes (1), acanthocephalans (1), and crustaceans (2). Only 4 species were common in at least I locality. Mean values for species richness, abundance, diversity, numerical dominance, and similarity in total (all species in the individual fish), gastrointestinal, and ectoparasite infracommunities were within ranges observed for most helminth infracommunities of marine fishes from temperate and tropical latitudes. These infracommunities had low species richness, abundance, diversity, and predictability (except ectoparasite infracommunities) and high dominance. Within the predictable element (common species), the specialist monogenean Pseudobicotylophora atlantica was the main reason for the increase in predictability because it was the only common species at all 4 localities. Host feeding habits, the distribution of intermediate hosts and infective stages, the local species pool, and a phylogenetic component seem to be determining the characteristics of these metazoan parasite infracommunities.     

Fucans, but not fucomannoglucuronans, determine the biological activities of sulfated polysaccharides from Laminaria saccharina brown seaweed

Sulfated polysaccharides from Laminaria saccharina (new name: Saccharina latissima) brown seaweed show promising activity for the treatment of inflammation, thrombosis, and cancer; yet the molecular mechanisms underlying these properties remain poorly understood. The aim of this work was to characterize, using in vitro and in vivo strategies, the anti-inflammatory, anti-coagulant, anti-angiogenic, and anti-tumor activities of two main sulfated polysaccharide fractions obtained from L. saccharina: a) L.s.-1.0 fraction mainly consisting of O-sulfated mannoglucuronofucans and b) L.s.-1.25 fraction mainly composed of sulfated fucans. Both fractions inhibited leukocyte recruitment in a model of inflammation in rats, although L.s.-1.25 appeared to be more active than L.s.-1.0. Also, these fractions inhibited neutrophil adhesion to platelets under flow. Only fraction L.s.-1.25, but not L.s.-1.0, displayed anticoagulant activity as measured by the activated partial thromboplastin time. Investigation of these fractions in angiogenesis settings revealed that only L.s.-1.25 strongly inhibited fetal bovine serum (FBS) induced in vitro tubulogenesis. This effect correlated with a reduction in plasminogen activator inhibitor-1 (PAI-1) levels in L.s.-1.25-treated endothelial cells. Furthermore, only parent sulfated polysaccharides from L. saccharina (L.s.-P) and its fraction L.s.-1.25 were powerful inhibitors of basic fibroblast growth factor (bFGF) induced pathways. Consistently, the L.s.-1.25 fraction as well as L.s.-P successfully interfered with fibroblast binding to human bFGF. The incorporation of L.s.-P or L.s.-1.25, but not L.s.-1.0 into Matrigel plugs containing melanoma cells induced a significant reduction in hemoglobin content as well in the frequency of tumor-associated blood vessels. Moreover, i.p. administrations of L.s.-1.25, as well as L.s.-P, but not L.s.-1.0, resulted in a significant reduction of tumor growth when inoculated into syngeneic mice. Finally, L.s.-1.25 markedly inhibited breast cancer cell adhesion to human platelet-coated surfaces. Thus, sulfated fucans are mainly responsible for the anti-inflammatory, anticoagulant, antiangiogenic, and antitumor activities of sulfated polysaccharides from L. saccharina brown seaweed.     

Flavonoids from two Lonchocarpus species of the Yucatan Peninsula

Leaves, stem bark and root of Lonchocarpus xuul and Lonchocarpus yucatanensis were studied separately. A chalcone, 2',4-dimethoxy-6'-hydroxylonchocarpin (), and the flavones 5,4'-dihydroxy-3'-methoxy-(6:7)-2,2-dimethylpyranoflavone (2) and 5,4'-dimethoxy-(6:7)-2,2-dimethylpyrano-flavone (3), together with the known carpachromene (4), were isolated from the leaves of both species. Similarly, the previously reported flavans xuulanin (5) and 3beta-methoxyxuulanin (6), together with the novel 3beta,4beta,5-trimethoxy-4'-hydroxy-(6:7)-2,2-dimethylpyranoflavan (7), 3-hydroxy-4,5-dimethoxy-(6:7)-2,2-dimethyl-pyranoflavan (8), and 3,4-dihydroxy-5-methoxy-(6:7)-2,2-dimethylpyranoflavan (10), were isolated from the stem bark and root of both species. Finally, the known 2',4'-dihydroxy-3'-(3-methylbut-2-enyl) chalcone (13) was obtained from the root of L. xuul only. The structures of the various metabolites were established by interpretation of their spectroscopic data.     

Isolation, purification, and characterization of fucose-containing sulfated polysaccharides from the brown seaweed Ecklonia kurome and their blood-anticoagulant activities

A sulfated polysaccharide fraction, obtained from the hot-water extract of the brown seaweed, Ecklonia kurome by removing laminaran and the major part of alginic acid, gave sulfated polysaccharides (B-I, B-II, C-I, and C-II) by both anion-exchange chromatography on a column of Ecteola-cellulose and by fractional precipitation with ethanol containing 0.3% calcium acetate, and then by gel-filtration chromatography on a Sepharose 4B column. B-I and B-II are composed of fucose, galactose, mannose, xylose, glucuronic acid, and ester sulfate in the approximate molar ratios of 1.00:0.36:0.48:1.08:1.85:2.35 and 1.00:0.81:0.18:0.45:0.61:2.00, respectively. C-I and C-II are composed of fucose, galactose, glucuronic acid, and ester sulfate in approximate molar ratios of 1.00:0.03:0.03:1.61 and 1.00:0.19:0.07:1.48, respectively. Blood-anticoagulant activities with respect to activated partial thromboplastin time (APTT) were approximately 24, 19, 81, and 85% of that of heparin for B-I, B-II, C-I, and C-II, respectively. All the polysaccharides showed slight antithrombin activity. No antifactor Xa activity was observed for any of the polysaccharides.     

Karyotype polymorphism in the cycad Zamia loddigesii (Zamiaceae) of the Yucatan Peninsula, Mexico

The cycad %amia loddigesii Miq. forms a morphologically variable complex on the Yucatan peninsula, Mexico. Several diploid chromosome numbers have been found in the species: In = 17, 24, 25, 26 and 27. Differing karyotypes and chromosome numbers were found in individuals of the same population and die karyotypes differ widely in numbers of metacentric and telocentric chromosomes present. Centrometric fission as well as pericentric inversions and unequal translocations are suggested to be the probable mechanisms for this karyotype variation. There appears to be a correlation between high chromosome number and increasing dryness of the habitats. Coupled with the strongly asymmetrical karyotypes, this suggests that karyotype evolution in Z- loddigesii is recent.     

Historical biogeography and distribution of the freshwater calanoid copepods (Crustacea: Copepoda) of the Yucatan Peninsula, Mexico

Aim To determine and analyse the distribution of the freshwater calanoid copepod (Diaptomidae and Pseudodiaptomidae) fauna of the Yucatan Peninsula (YP) and its relation to the geological history of this Neotropical karstic plain. Location The Yucatan Peninsula, Mexico. Methods Plotting of geo‐referenced sites, analysis of local and regional geological history, analysis and comparison of regional and local records. Results The current composition and distribution of Diaptomidae and Pseudodiaptomidae in the YP mainly reflects recent, post‐Pliocene colonization events. This invasion did not reach America, but only parts of Central America (CA). The presence of diaptomids in the continent since the pre‐Cretaceous and the presumed post‐Cretaceous (Palaeocene–Oligocene) radiation of Diaptomidae in Middle America suggest earlier colonizations of the YP. The marine transgressions kept most of the YP submerged in different geological periods, thus eliminating any original primary freshwater colonizers, such as the diaptomids. The periods of marine regression probably represented opportunities for new waves of diaptomid colonization of the YP. The latest dispersal of diaptomids in the YP during the Holocene (8000 yr bp ) was probably an intermittent process because of the alternative dry and wet periods and interglacial transgressions. The presence of the Nearctic Leptodiaptomus and Arctodiaptomus in the YP and the current distribution of Mastigodiaptomus might represent remnants of earlier invasions of Diaptomidae in Middle America. The Neotropical Mastigodiaptomus probably originated in the Late Cretacic CA/proto‐Antilles complex. Forms derived from a M. albuquerquensis type ancestor radiated into the YP leaving relatively isolated populations of three species in the northern half of the peninsula. The distribution of the brackish water Pseudodiaptomus marshi well inside the coastline might have resulted from stranding and subsequent adaptation of this species during a marine regression in the Bacalar formation; this agrees with the vision of this taxon as being in process of invasion of freshwater environments. Main conclusions It is not probable that the South American (SA) diaptomid fauna originated from an invasion of upper Neotropical/Nearctic forms. The current distribution of freshwater calanoid copepods reflects relatively recent, post‐Pliocene biogeographical patterns, but probably older patterns are involved as well. The northern and eastern coasts of the Yucatan are the most recently colonized by diaptomids. Differing from other freshwater groups surveyed in the Yucatan that have marine relatives (i.e. fishes, amphipods, isopods, mysids, macrocrustaceans), there is no evidence of local vicariant events involving cave‐dwelling forms or marine relicts in the diaptomid fauna of the YP.     

Mangrove sinkholes (cenotes) of the Yucatan Peninsula,a global hotspot of carbon sequestration

Mangroves are among the most carbon-dense ecosystems on the planet. The capacity of mangroves to store and accumulate carbon has been assessed and reported at regional, national and global scales. However, small-scale sampling is still revealing ‘hot spots’ of carbon accumulation. This study reports one of these hotspots, with one of the largest-recorded carbon stocks in mangroves associated with sinkholes (cenotes) in the Yucatan Peninsula, Mexico. We assessed soil organic carbon (SOC) stocks, sequestration rates and carbon origin of deep peat soils (1 to 6 m). We found massive amounts of SOC up to 2792 Mg C ha⁻¹, the highest value reported in the literature so far. This SOC is primarily derived from highly preserved mangrove roots and has changed little since its deposition, which started over 3220 years ago (±30 BP). Most cenotes are owned by Mayan communities and are threatened by increased tourism and the resulting extraction and pollution of groundwater. These hot spots of carbon sequestration, albeit small in area, require adequate protection and could provide valuable financial opportunities through carbon-offsetting mechanisms and other payments for ecosystem services.     

Hydrogeochemical and biological characteristics of cenotes in the Yucatan Peninsula (SE Mexico)

Cenotes (sinkholes) are the most peculiar aquatic ecosystem of the Yucatan Peninsula (SE Mexico). They are formed by dissolution of the carbonate rock in the karstic platform of the Yucatan Peninsula. A wide morphological variety is observed from caves filled with ground water to open cenotes. In some cenotes, particularly those close to the sea, underneath the fresh water one finds saltwater, where meromixis can take place. This occurs because in the Yucatan Peninsula there is a thin lens (10s of meters thick) that floats above denser saline water. In these cenotes, a relative enrichment of sodium related to calcium is observed while conductivity increases. In contrast, a higher increase of calcium associated to sulfate is observed in cenotes located in SE Yucatan Peninsula. A marked vertical stratification of the water is established during the warm and rainy season of the year (May–October). In cenotes with good hydraulic connection with the rest of the aquifer, the water remains clear during most of the year. However, cenotes with poor hydraulic connection with the aquifer are characterized by turbid waters and very low light transparency. In this group of cenotes, the water column contains a high concentration of chlorophyll (mostly due to chlorophyceans, cyanobacteria, diatoms and dinoflagellates); the hypolimnion and the sediment are rich in organic matter and anaerobic bacteria mediated biogeochemical processes are dominant. The upper part of the cenotes walls is well illuminated and covered by a rich microbial mat. Floating macrophytes may also occupy part of the water surface in oligotrophic cenotes. A great variety of food web paths are represented in the habitats occurring in the cenotes, in which few trophic levels are involved. A few endemic species (crustaceans and fishes) have been reported from cenotes found in the Yucatan Peninsula. Because of the high organic matter input (alochthonous) and production (autochthonous) and the low water flow, cenotes can be considered heterotrophic systems.     

Allelochemicals from Stauranthus perforatus, a Rutaceous tree of the Yucatan Peninsula, Mexico

Aqueous leachates and a CHCl3-MeOH (1:1) extract of roots of Stauranthus perforatus showed a significant phytotoxic effect on Amaranthus hypochondriacus and Echinochloa crus-galli. Bioassay-directed fractionation of the active organic extract led to the isolation and characterization of ten secondary metabolites, which included two pyranocoumarins [xanthyletin (1) and 3-(1',1'-dimethylallyl)-xanthyletin (2)], four furanocoumarins [chalepensin (3), ammirin (4), chalepin (5) and 2'-isopropyl-psoralene (6)], two lignans [asarinin (7) and fargesin (8)], one sesquiterpene [4,5-epoxi-beta-caryophyllene (9)], and one alkamide [pellitorine (10)]. From these compounds, 2'-isopropyl-psoralene (6) or anhydromarmesin, is reported for the first time as a natural product, whereas compounds 4-10 are now reported as being present in S. perforatus. Metabolites 1, 3-5 and 10 caused significant inhibition of radicle growth of A. hypochondriacus and E. crus-galli. Furthermore, in a greenhouse experiment the decomposition of the leaves and roots in the soil had a significant inhibitory effect on the growth of weeds. The allelopathic action of the decomposition of roots was evident up to the sixth week of the experiment. The effect of leaves was comparable to that of DPCA (dimethyl tetrachloroterephthalate), a commercial herbicide. Finally different concentrations of Stauranthus root powder were combined with maize kernels and used to feed corn weevil. The treatments resulted in high mortality of this insect.     

Seasonal transmission of Leishmania (Leishmania) mexicana in the state of Campeche, Yucatan Peninsula, Mexico

In the Yucatan Peninsula, Mexico, localized cutaneous leishmaniasis (LCL) caused by Leishmania (Leishmania) mexicana is a typical wild zoonosis restricted to the forest, and humans are only accidentally involved. The transmission of L. (L.) mexicana has been related to the patient's occupation: "chicleros" (gum collectors) and agricultural workers. The objective of this study was to document L. (L.) mexicana seasonally of transmission in endemic areas of LCL in the state of Campeche, Yucatan Peninsula, Mexico. The timing of incidence of LCL in humans during 1993-1994, as well as the rate and time of infection in rodents and sand flies between February 1993 and March 1995 were analyzed. Rodents and sand flies were found infected between November and March, when men carried out their field activities and are exposed. Based on results analyzed, it is concluded that L. (L.) mexicana in the endemic area of LCL in the state of Campeche, Yucatan Peninsula, Mexico, presents a seasonal transmission restricted to the months of November to March. The knowledge of the timing of the transmission cycle in an endemic area of leishmaniasis is very important because intervention measures on the high-risk focus and population might be restricted.     

DNA Barcoding and Demographic History of Peromyscus yucatanicus (Rodentia: Cricetidae) Endemic to the Yucatan Peninsula,Mexico

Journal of Mammalian Evolution - The Yucatan Peninsula (YP) is a biotic province located in southeastern Mexico, delimited mainly by climatic variables. One endemic species of the YP is the Yucatan...     

3800 Years of Quantitative Precipitation Reconstruction from the Northwest Yucatan Peninsula

Precipitation over the last 3800 years has been reconstructed using modern pollen calibration and precipitation data. A transfer function was then performed via the linear method of partial least squares. By calculating precipitation anomalies, it is estimated that precipitation deficits were greater than surpluses, reaching 21% and <9%, respectively. The period from 50 BC to 800 AD was the driest of the record. The drought related to the abandonment of the Maya Preclassic period featured a 21% reduction in precipitation, while the drought of the Maya collapse (800 to 860 AD) featured a reduction of 18%. The Medieval Climatic Anomaly was a period of positive phases (3.8–7.6%). The Little Ice Age was a period of climatic variability, with reductions in precipitation but without deficits.