Immune and clinical parameters associated with Leishmania infantum infection in the golden hamster model     

Requena JM  Soto M  Doria MD  Alonso C 《Veterinary immunology and immunopathology》2000,76(3-4):269-281

For experimental infections with viscerotropic strains of Leishmania, a suitable animal model is not yet defined. In the present work, we have reappraised the use of golden hamster (Mesocricetus auratus) as an experimental model for infection with Leishmania infantum. Groups of hamsters were challenged by the intracardial route with doses ranging from 10(3) to 10(5) infectious promastigotes and the animals were monitored for 1-year follow-up period. The outcome of the infection was assessed by clinical symptoms of leishmaniasis, parasite loads in both liver and spleen, humoral response to Leishmania antigens and antibody levels in kidneys. The humoral response was analysed using either crude antigens (by ELISA and Western blotting) or several recombinant Leishmania antigens (Hsp70, Hsp83, LiP2a, LiP2b, H2A, H3 and KMP-11). From the analysis of all these parameters, we established the existence of three groups of animals: symptomatic or susceptible, oligosymptomatic, and resistant. Given the parallelism existing between the outcomes of Leishmania-infection in hamsters, dogs and humans, we believe that our data illustrate that the hamster is an excellent experimental model to study visceral leishmaniasis and for the design of vaccine development.  相似文献   

Exploring Patterns of Exotic Earthworm Distribution in a Temperate Hardwood Forest in South-Central New York, USA     

Esteban R. Suárez  Geraldine L. Tierney  Timothy J. Fahey  Robert Fahey 《Landscape Ecology》2006,21(2):297-306

Exotic earthworms invading forests in Canada and northeastern United States that were naturally devoid of large detritivores cause major changes in ecosystem function. To assess their long-term impacts, studies are needed to elucidate the factors that control the patterns of earthworm invasion at the landscape level. We analyzed the distribution patterns of exotic earthworms in a northern hardwood forest in south-central New York (USA), as explained by landscape variables thought to be important in determining earthworm distribution. Forest type, slope angle, elevation, and the distance to agricultural clearings and wet refugia were significant predictors of earthworm presence, whereas local wetness index and the distance to streams and roads were not. Forest type and distance to agricultural clearings were the two most significant predictors. Our data suggest that areas close to agricultural clearings, dominated by mixed hardwoods, and located towards valley bottoms or on gentle slopes are very likely to support communities of exotic earthworms. Steeper slopes, areas dominated by American beech or eastern hemlock, and locations in the core of extensive forest landscapes have lower probabilities of invasion by exotic earthworms. When applied to a nearby area, our statistical model correctly predicted earthworm presence for 67% of 377 sampling points. Most of the mistakes were incorrect predictions of earthworm absence, suggesting that our statistical model slightly underestimated earthworm presence, possibly because of the pervasive influence of active agricultural fields adjacent to the test site.  相似文献   

Narrow genetic base in forest restoration with holm oak (Quercus ilex L.) in Sicily     

Concetta Burgarella  Miguel Navascués  Álvaro Soto  Ángel Lora  Silvio Fici 《Annals of Forest Science》2007,64(7):757-763

In order to empirically assess the effect of actual seed sampling strategy on genetic diversity of holm oak (Quercus ilex) forestations in Sicily, we have analysed the genetic composition of two seedling lots (nursery stock and plantation) and their known natural seed origin stand by means of six nuclear microsatellite loci. Significant reduction in genetic diversity and significant difference in genetic composition of the seedling lots compared to the seed origin stand were detected. The female and the total effective number of parents were quantified by means of maternity assignment of seedlings and temporal changes in allele frequencies. Extremely low effective maternity numbers were estimated (Nf _e ≈ 2–4) and estimates accounting for both seed and pollen donors gave also low values (N _e ≈ 35–50). These values can be explained by an inappropriate forestry seed harvest strategy limited to a small number of spatially close trees.  相似文献   

The Control of Reactive Oxygen Species Influences Porcine Oocyte In Vitro Maturation          下载免费PDF全文

GM Alvarez  SA Morado  MP Soto  GC Dalvit  PD Cetica 《Reproduction in domestic animals》2015,50(2):200-205

The aim of this study was to examine the effect of varying intracellular reactive oxygen species (ROS) levels during oocyte in vitro maturation with enzymatic ROS production systems (xanthine + xanthine oxidase or xanthine + xanthine oxidase + catalase), scavenger systems (catalase or superoxide dismutase + catalase) or cysteine on porcine oocyte maturation. Oocyte ROS levels showed an increase when H₂O₂ or O₂?^‐ production systems were added to the culture medium (p < 0.05). On the other hand, the presence of ROS scavengers in the maturation medium did not modify oocyte ROS levels compared with the control after 48 h of maturation, but the addition of cysteine induced a decrease in oocyte ROS levels (p < 0.05). The ROS production systems used in this work did not modified the percentage of oocyte nuclear maturation, but increased the decondensation of sperm head (p < 0.05) and decreased the pronuclear formation (p < 0.05). In turn, the addition of O₂?^‐ and H₂O₂ scavenging systems during in vitro maturation did not modify the percentage of oocytes reaching metaphase II nor the oocytes with decondensed sperm head or pronuclei after fertilization. However, both parameters increased in the presence of cysteine (p < 0.05). The exogenous generation of O₂?^‐ and H₂O₂ during oocyte in vitro maturation would not affect nuclear maturation or later sperm penetration, but most of the spermatozoa cannot progress to form the pronuclei after fusion with the oocyte. The decrease in endogenous ROS levels by the addition of cysteine would improve pronuclear formation after sperm penetration.  相似文献   

Neotropical Bats from Costa Rica harbour Diverse Coronaviruses          下载免费PDF全文

A. Moreira‐Soto  N. Vargas‐Vargas  B. Rodríguez‐Herrera  C. Jiménez  E. Corrales‐Aguilar 《Zoonoses and public health》2015,62(7):501-505

Bats are hosts of diverse coronaviruses (CoVs) known to potentially cross the host–species barrier. For analysing coronavirus diversity in a bat species‐rich country, a total of 421 anal swabs/faecal samples from Costa Rican bats were screened for CoV RNA‐dependent RNA polymerase (RdRp) gene sequences by a pancoronavirus PCR. Six families, 24 genera and 41 species of bats were analysed. The detection rate for CoV was 1%. Individuals (n = 4) from four different species of frugivorous (Artibeus jamaicensis, Carollia perspicillata and Carollia castanea) and nectivorous (Glossophaga soricina) bats were positive for coronavirus‐derived nucleic acids. Analysis of 440 nt. RdRp sequences allocated all Costa Rican bat CoVs to the α‐CoV group. Several CoVs sequences clustered near previously described CoVs from the same species of bat, but were phylogenetically distant from the human CoV sequences identified to date, suggesting no recent spillover events. The Glossophaga soricina CoV sequence is sufficiently dissimilar (26% homology to the closest known bat CoVs) to represent a unique coronavirus not clustering near other CoVs found in the same bat species so far, implying an even higher CoV diversity than previously suspected.  相似文献   

A disaggregated dynamic model for predicting volume,biomass and carbon stocks in even-aged pedunculate oak stands in Galicia (NW Spain)     

Esteban Gómez-García  Felipe Crecente-Campo  Marcos Barrio-Anta  Ulises Diéguez-Aranda 《European Journal of Forest Research》2015,134(3):569-583

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Advanced broodstock diets for the mangrove red snapper and a potential importance of arachidonic acid in eggs and fry     

Arnil C. Emata  Hiroshi Y. Ogata  Esteban S. Garibay  Hirofumi Furuita 《Fish physiology and biochemistry》2003,28(1-4):489-491

Mangrove red snapper fed advanced broodstock diets containing squid meal and squid oil exhibited higher hatching rates, cumulative survival and survival activity index than those fed a basal diet or a basal diet supplemented with mixture of antioxidants. On the other hand, fatty acid analyses of ovaries and fry of wild fish and eggs and larvae of broodstock fed raw fish revealed high arachidonic acid (ARA) and docosahexaenoic acid (DHA) levels and relatively lower eicosapentaenoic acid (EPA) levels consequently showing high ARA/EPA and DHA/EPA ratios compared to cold water species. This suggests that ARA may be nutritionally more important for egg and larval development and survival in tropical marine fish and its supplementation in broodstock diets may enhance reproductive performance of mangrove red snapper.  相似文献   

Participation of ascorbic acid in the dormancy establishment of poplar lateral branch buds     

Gustavo Esteban Gergoff Grozeff  Carlos Guillermo Bartoli 《Journal of Forest Research》2014,19(2):301-304

This work studied the participation of ascorbic acid (AA) in the dormancy establishment of apical buds of poplar (Populus deltoides Bartram ex Marshall cv. Catfish 2) lateral branches. AA content was highest during the active growth period and decreased to the lowest content during bud dormancy. The accumulation of the oxidised form, dehydroascorbate, was similar in either growth or dormant bud stages. The supplementation of buds with AA at the end of the summer delayed bud set. Similarly, the supplementation of buds with gibberellic acid extended the growth period and kept a high AA content in the apoplast. These results suggest that a decrease in the accumulation of reduced AA might be needed for the dormancy establishment in apical buds of poplar lateral branches.  相似文献   

First indications for the involvement of strigolactones on nodule formation in alfalfa (Medicago sativa)     

María J. Soto 《Soil biology & biochemistry》2010,42(2):383-15743

Strigolactones have recently been suggested to be phytohormones that are present in all plants. Strigolactones are released by roots into the rhizosphere, stimulating the seed germination of parasitic plants such as Striga spp. and Orobanche spp. and play a crucial role in the interaction between plants and symbiotic arbuscular mycorrhizal fungi.By applying different concentrations of the synthetic strigolactone analogue GR24 to alfalfa (Medicago sativa) inoculated with Sinorhizobium meliloti we could show that in alfalfa nodulation is positively affected by the presence of the strigolactone analogue GR24. Moreover, we could show that this increased nodulation cannot be linked with a stimulatory effect of GR24 on the growth or the expression of nod genes of S. meliloti.Putative mechanisms operating in the plant in response to the addition of GR24 and leading to increased nodule formation by rhizobia are discussed.  相似文献   

Coffee agroecosystem performance under full sun, shade, conventional and organic management regimes in Central America   总被引：1，自引：0，他引：1  

J. Haggar  M. Barrios  M. Bola?os  M. Merlo  P. Moraga  R. Munguia  A. Ponce  S. Romero  G. Soto  C. Staver  E. de M. F. Virginio 《Agroforestry Systems》2011,82(3):285-301

Changes in coffee economics are leading producers to reduce agrochemical use and increase the use of shade. Research is needed on how to balance the competition from shade trees with the provision of ecological services to the coffee. In 2000, long-term coffee experiments were established in Costa Rica and Nicaragua to compare coffee agroecosystem performance under full sun, legume and non-legume shade types, and intensive and moderate conventional and organic inputs. Coffee yield from intensive organic production was not significantly different from intensive conventional in Nicaragua, but in Costa Rica it was lower during three of the six harvests. Full sun coffee production over 6 years was greater than shaded coffee in Costa Rica (61.8 vs. 44.7 t ha^?1, P = 0.0002). In Nicaragua, full sun coffee production over 5 years (32.1 t ha^?1) was equal to coffee with shade that included Tabebuia rosea (Bertol.) DC., (27?C30 t ha^?1) and both were more productive (P = 0.03) than coffee shaded with Inga laurina (Sw.) Willd. (21.6 t ha^?1). Moderate input organic production was significantly lower than other managements under all shade types, except in the presence of Erythrina poepiggina (Walp.) O.F. Cook. Inga and Erythrina had greater basal area and nutrient recycling from prunings than other shade species. Intensive organic production increased soil pH and P, and had higher K compared to moderate conventional. Although legume shade trees potentially provide ecological services to associated coffee, this depends on management of the competition from those same trees.  相似文献