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91.
Martina Ferraguti Josu Martínez-de la Puente Miguel ngel JimnezClavero Francisco Llorente David Roiz Santiago Ruiz Ramn Soriguer Jordi Figuerola 《PLoS pathogens》2021,17(6)
The Dilution Effect Hypothesis (DEH) argues that greater biodiversity lowers the risk of disease and reduces the rates of pathogen transmission since more diverse communities harbour fewer competent hosts for any given pathogen, thereby reducing host exposure to the pathogen. DEH is expected to operate most intensely in vector-borne pathogens and when species-rich communities are not associated with increased host density. Overall, dilution will occur if greater species diversity leads to a lower contact rate between infected vectors and susceptible hosts, and between infected hosts and susceptible vectors. Field-based tests simultaneously analysing the prevalence of several multi-host pathogens in relation to host and vector diversity are required to validate DEH. We tested the relationship between the prevalence in house sparrows (Passer domesticus) of four vector-borne pathogens–three avian haemosporidians (including the avian malaria parasite Plasmodium and the malaria-like parasites Haemoproteus and Leucocytozoon) and West Nile virus (WNV)–and vertebrate diversity. Birds were sampled at 45 localities in SW Spain for which extensive data on vector (mosquitoes) and vertebrate communities exist. Vertebrate censuses were conducted to quantify avian and mammal density, species richness and evenness. Contrary to the predictions of DEH, WNV seroprevalence and haemosporidian prevalence were not negatively associated with either vertebrate species richness or evenness. Indeed, the opposite pattern was found, with positive relationships between avian species richness and WNV seroprevalence, and Leucocytozoon prevalence being detected. When vector (mosquito) richness and evenness were incorporated into the models, all the previous associations between WNV prevalence and the vertebrate community variables remained unchanged. No significant association was found for Plasmodium prevalence and vertebrate community variables in any of the models tested. Despite the studied system having several characteristics that should favour the dilution effect (i.e., vector-borne pathogens, an area where vector and host densities are unrelated, and where host richness is not associated with an increase in host density), none of the relationships between host species diversity and species richness, and pathogen prevalence supported DEH and, in fact, amplification was found for three of the four pathogens tested. Consequently, the range of pathogens and communities studied needs to be broadened if we are to understand the ecological factors that favour dilution and how often these conditions occur in nature. 相似文献
92.
93.
E. Cano A. Cano-Ortiz S. Del Río A. Veloz Ramirez F. J. Esteban Ruiz 《Plant biosystems》2013,147(2):200-212
This paper presents a floristic and vegetation study of the serpentinised territories of the Dominican Republic, corresponding to the Yamasá and Prieta mountains, Dajabón, Puerto Plata and Gaspar Henández. These sites are very important at a local level as they act as speciation centres and have a specific ultramafic flora with a high endemicity rate. The floristic analysis revealed the existence of 219 species, of which 54 (24.7%) are endemic. Twenty-one plots of vegetation distributed in five areas dominated by serpentines have been analysed in this study. The phytosociological approach is based on the Braun-Blanquet method. The study was combined with statistical techniques such as multivariate analyses. The results revealed three different kinds of forests, one dominated by the endemic Bignoniaceae, Tabebuia berterii (CC.) Britton, which is peculiar to the subhumid–humid environments of the Caribbean-Cibensean territory. The second type of forest is dominated by the serpentinophyte Polygonaceae, Leptogonum buchii Urb. which thrives in the humid ombrotype of the north territory. Finally, the third one adopts the form of the pine forest of Dajabón, dominated by Pinus occidentalis Sw. Four associations and three alliances are proposed as new syntaxa based on statistical and phytosociological analyses. 相似文献
94.
95.
Z. Arbib J. Ruiz Pablo Álvarez-Díaz C. Garrido-Pérez J. Barragan J. A. Perales 《International journal of phytoremediation》2013,15(8):774-788
Nitrogen and phosphorus concentration in the effluent of a wastewater treatment plant can vary significantly, which could affect the growth kinetic and chemical composition of microalgae when cultivated in this medium. The aim of this work was to study the rate of growth, nutrient removal and carbon dioxide biofixation as well as biomass composition of Scenedesmus obliquus (S. obliquus) when it is cultivated in wastewater at different nitrogen and phosphorus ratio, from 1:1 to 35:1. A more homogeneous method for calculating productivities in batch reactors was proposed. The proper N:P ratio for achieving optimum batch biomass productivity ranged between 9 and 13 (263 and 322 mg L?1 d?1 respectively). This was also the ratio range for achieving a total N and P removal. Above and below this range (9–13) the maximum biomass concentration changed, instead of the specific growth rate.The maximum carbon dioxide biofixation rate was achieved at N:P ratio between 13 and 22 (553 and 557 mg CO2 L?1 d?1 respectively). Lipid and crude protein content, both depend on the aging culture, reaching the maximum lipid content (34%) at the lowest N:P (1:1) and the maximum crude protein content (34.2%) at the highest N:P (35:1). 相似文献
96.
97.
Cesar Ruiz Katherine Valderrama Sven Zea Leonardo Castellanos 《Marine biotechnology (New York, N.Y.)》2013,15(5):571-583
Biotechnological research on marine organisms, such as ex situ or in situ aquaculture and in vitro cell culture, is being conducted to produce bioactive metabolites for biomedical and industrial uses. The Caribbean marine sponge Discodermia dissoluta is the source of (+)-discodermolide, a potent antitumoural polyketide that has reached clinical trials. This sponge usually lives at depths greater than 30 m, but at Santa Marta (Colombia) there is a shallower population, which has made it logistically possible to investigate for the first time, on ways to supply discodermolide. We thus performed in situ, 6-month fragment culture trials to assess the performance of this sponge in terms of growth and additional discodermolide production and studied possible factors that influence the variability of discodermolide concentrations in the wild. Sponge fragments cultured in soft mesh bags suspended from horizontal lines showed high survivorship (93 %), moderate growth (28 % increase in volume) and an overall rise (33 %) in the discodermolide concentration, equivalent to average additional production of 8 μg of compound per millilitre of sponge. The concentration of discodermolide in wild sponges ranged from 8 to 40 μg mL?1. Locality was the only factor related to discodermolide variation in the wild, and there were greater concentrations in peripheral vs. basal portions of the sponge, and in clean vs. fouled individuals. As natural growth and regeneration rates can be higher than culture growth rates, there is room for improving techniques to sustainably produce discodermolide. 相似文献
98.
Martha Lissete Morales Villarreal Marina Padilha Antonio Diogo Silva Vieira Bernadette Dora Gombossy de Melo Franco Rafael Chacon Ruiz Martinez Susana Marta Isay Saad 《PloS one》2013,8(12)
Species-specific Quantitative Real Time PCR (qPCR) alone and combined with the use of propidium monoazide (PMA) were used along with the plate count method to evaluate the survival of the probiotic strains Lactobacillus acidophilus La-5 and Bifidobacterium animalis subsp. lactis Bb-12, and the bacteriocinogenic and potentially probiotic strain Lactobacillus sakei subsp. sakei 2a in synbiotic (F1) and probiotic (F2) petit-suisse cheeses exposed throughout shelf-life to in vitro simulated gastrointestinal tract conditions. The three strains studied showed a reduction in their viability after the 6 h assay. Bb-12 displayed the highest survival capacity, above 72.6 and 74.6% of the initial populations, respectively, by plate count and PMA-qPCR, maintaining population levels in the range or above 6 log CFU/g. The prebiotic mix of inulin and FOS did not offer any additional protection for the strains against the simulated gastrointestinal environment. The microorganisms'' populations were comparable among the three methods at the initial time of the assay, confirming the presence of mainly viable and culturable cells. However, with the intensification of the stress induced throughout the various stages of the in vitro test, the differences among the methods increased. The qPCR was not a reliable enumeration method for the quantification of intact bacterial populations, mixed with large numbers of injured and dead bacteria, as confirmed by the scanning electron microscopy results. Furthermore, bacteria plate counts were much lower (P<0.05) than with the PMA-qPCR method, suggesting the accumulation of stressed or dead microorganisms unable to form colonies. The use of PMA overcame the qPCR inability to differentiate between dead and alive cells. The combination of PMA and species-specific qPCR in this study allowed a quick and unequivocal way of enumeration of viable closely related species incorporated into probiotic and synbiotic petit-suisse cheeses and under stress conditions. 相似文献
99.
Cesar D. Bordenave Francisco J. Escaray Ana B. Menendez Eva Serna Pedro Carrasco Oscar A. Ruiz Andrés Gárriz 《PloS one》2013,8(12)
Lotus japonicus is a model legume broadly used to study many important processes as nitrogen fixing nodule formation and adaptation to salt stress. However, no studies on the defense responses occurring in this species against invading microorganisms have been carried out at the present. Understanding how this model plant protects itself against pathogens will certainly help to develop more tolerant cultivars in economically important Lotus species as well as in other legumes. In order to uncover the most important defense mechanisms activated upon bacterial attack, we explored in this work the main responses occurring in the phenotypically contrasting ecotypes MG-20 and Gifu B-129 of L. japonicus after inoculation with Pseudomonas syringae DC3000 pv. tomato. Our analysis demonstrated that this bacterial strain is unable to cause disease in these accessions, even though the defense mechanisms triggered in these ecotypes might differ. Thus, disease tolerance in MG-20 was characterized by bacterial multiplication, chlorosis and desiccation at the infiltrated tissues. In turn, Gifu B-129 plants did not show any symptom at all and were completely successful in restricting bacterial growth. We performed a microarray based analysis of these responses and determined the regulation of several genes that could play important roles in plant defense. Interestingly, we were also able to identify a set of defense genes with a relative high expression in Gifu B-129 plants under non-stress conditions, what could explain its higher tolerance. The participation of these genes in plant defense is discussed. Our results position the L. japonicus-P. syringae interaction as a interesting model to study defense mechanisms in legume species. 相似文献
100.
Emilio García García María-Ángeles Vázquez López Rafael Galera Martínez Irene Alias Manuel Martín González Antonio Bonillo Perales José Eugenio Cabrera Sevilla Icíar García Escobar Sara Gómez Bueno Encarnación López Ruzafa Francisco-Javier Muñoz Vico Patricia Oliva Pérez María Ortiz Pérez Juan Poveda González Marisa Rodríguez Lucenilla Firma-Isabel Rodríguez Sánchez Ana Ruiz Sánchez Lucía Ruiz Tudela Sara Torrico 《Endocrinología y nutrición》2013,60(3):121-126
ObjectivesTo estimate the prevalence of obesity and overweight in children and adolescents in our city and to investigate the associated factors.Subjects and methodsA cross-sectional study of 1317 children and adolescents aged 2-16 years. Multistage probability sampling was used to select three groups of subjects: 411 aged 12 to 16 years, 504 aged 6 to 12 years, and 402 aged 2 to 6 years. Body mass index was calculated, and obesity and overweight were diagnosed using the threshold levels of the International Obesity Task Force for children and adolescents. Parents were asked about eating habits, health, social, and demographic aspects. Results are given as percentages (95% confidence interval). The relationship between obesity and overweight and the different variables was studied using multiple logistic regression. The adjusted odds ratio (OR) was calculated.ResultsAmong children and adolescentes aged 2-16 years, 9.5% (8.0%-11.0%) were obese and 22.4% (23.3%-24.6%) were overweight. Of subjects aged 12-16 years, 8.5% (5.9%-11.2%) were obese and 20.5% (16.7%-24.3%) were overweight. In the groups aged 6-12 years and 2-6 years, rates of obesity and overweight were 11.6% (8.9% -14.3%) and 31.0% (27.0-35.0) and 8.0% (5.4%-10.6%) and 13.6% (10.3%-16.9%) respectively. Obesity or overweight was associated to age (OR 1.21; P< 0.001), maternal obesity (OR 10.99; P= 0.008), a birthweight higher than 4 kg (OR 2.91; p 0.002), and formula feeding (OR 1.82; P= 0.005).ConclusionObesity and overweight in children and adolescents are highly prevalent problems in our city. 相似文献