Small todents fleas from the bubonic plague focus located in the Serra dos Órgãos Mountain Range, State of Rio de Janeiro, Brazil

Eleven species of fleas were collected from 601 small rodents, from November 1995 to October 1997, in areas of natural focus of bubonic plague, including the municipalities of Nova Friburgo, Sumidouro and Teresópolis, State of Rio de Janeiro, Brazil. Among 924 fleas collected, Polygenis (Polygenis) rimatus (Rhopalopsyllidae) was the predominant species regarding the frequency, representing 41.3% (N:382), followed by P. (Neopolygenis) pradoi, representing 20% (N:185) and Craneopsylla minervaminerva (Stephanocircidae), representing 18.9% (N:175). The host Akodon cursor harbored 47.9% of these fleas. Other six host species were infested by 52.1% of the remaining fleas. Fleas were found on hosts and in places within the focus not previously reported by the literature.

Domiciliation Trend of Panstrongylus rufotuberculatus in Colombia

The present paper presents evidence of the domiciliation of Panstrongylus rufotuberculatus in La Gardenia, Colombia through the collection of 2 unhatched eggs, 81 nymphs and 10 adults (4 males and 6 females), from 2 rural houses. The transmission risk indicators of Trypanosoma cruzi by P. rufotuberculatus in La Gardenia, were: domiciliary infestation 7.5%, density 2.35, colonization 66.6%, overcrowding 31.33, natural infection 4.6%, and relative infection 2.5%. These results and findings in Peru and Argentina, show that P. rufotuberculatus has a potential success in domiciliation and could some day become an alternate vector of American trypanosomiasis.

Performance of OptiMAL® in the diagnosis of Plasmodium vivax and Plasmodium falciparum infections in a malaria referral center in Colombia

Alternative, non-microscopic methods for the diagnosis of malaria have recently become available. Among these, rapid dipstick methods stand out. One such test, OptiMAL®, is based on the immunochromatographic detection of Plasmodium lactate dehydrogenase (pLDH) and has the capacity to detect and distinguish infections caused by P. falciparum and Plasmodium sp. This capacity is particularly important in countries where different species of Plasmodium co-exist. In this study we evaluated the performance of OptiMAL® in an urban referral center for malaria diagnosis. Two sets of patients were included: one (n = 112) having predetermined infections with P. falciparum or P. vivax and individuals with negative blood smears; and another consisting of all eligible consecutive patients (n = 80) consulting for diagnosis at the referral center during one month. The overall diagnostic efficiency of OptiMAL® for both sets of patients was 96.9%. Efficiency was higher for P. vivax (98.1%) than for P. falciparum (94.9%). These results corroborate the diagnostic utility of OptiMAL® in settings where P. vivax and P. falciparum co-exist and support its implementation where microscopic diagnosis is unavailable and in circumstances that exceed the capacity of the local microscopic diagnosis facility.

Prevalence and level of antibodies to the circumsporozoite protein of human malaria parasites in five states of the Amazon region of Brazil

The aim of this study was to determine the prevalence of malaria infection and antibodies against the repetitive epitopes of the circumsporozoite (CS) proteins of Plasmodium falciparum, P. malariae, P. vivax VK210, P. vivax VK247, and P. vivax-like in individuals living in the states of Rondônia, Pará, Mato Grosso, Amazonas, and Acre. Active malaria transmission was occurring in all studied sites, except in Acre. P. falciparum was the predominant species in Pará and Rondônia and P. vivax in Mato Grosso. Infection by P. malariae was low but this Plasmodium species was detected in Rondônia (3.5%), Mato Grosso (2.5%), and Pará (0.8%). High prevalence and levels of serological reactivity against the CS repeat peptides of P. falciparum were detected in Rondônia (93%) and Pará (85%). Sera containing antibodies against the CS repeat of P. malariae occurred more frequently in Rondônia (79%), Pará (76%), and Amazonas (68%). Antibodies against the repeat epitope of the standard CS protein of P. vivax VK210, P. vivax VK247, and P. vivax-like were more frequent in Rondônia, Pará, and Mato Grosso. The high frequency of reactions to P. malariae in most of the areas suggests that the infection by this Plasmodium species has been underestimated in Brazil.

Interaction between Paracoccidioides brasiliensis conidia and the coagulation system: involvement of fibrinogen

The infectious process starts with an initial contact between pathogen and host. We have previously demonstrated that Paracoccidioides brasiliensis conidia interact with plasma proteins including fibrinogen, which is considered the major component of the coagulation system. In this study, we evaluated the in vitro capacity of P. brasiliensis conidia to aggregate with plasma proteins and compounds involved in the coagulation system. We assessed the aggregation of P. brasiliensis conidia after incubation with human serum or plasma in the presence or absence of anticoagulants, extracellular matrix (ECM) proteins, metabolic and protein inhibitors, monosaccharides and other compounds. Additionally, prothrombin and partial thromboplastin times were determined after the interaction of P. brasiliensis conidia with human plasma. ECM proteins, monosaccharides and human plasma significantly induced P. brasiliensis conidial aggregation; however, anticoagulants and metabolic and protein inhibitors diminished the aggregation process. The extrinsic coagulation pathway was not affected by the interaction between P. brasiliensis conidia and plasma proteins, while the intrinsic pathway was markedly altered. These results indicate that P. brasiliensis conidia interact with proteins involved in the coagulation system. This interaction may play an important role in the initial inflammatory response, as well as fungal disease progression caused by P. brasiliensis dissemination.

Red blood cells derived from peripheral blood and bone marrow CD34+ human haematopoietic stem cells are permissive to Plasmodium parasites infection

The production of fully functional human red cells in vitro from haematopoietic stem cells (hHSCs) has been successfully achieved. Recently, the use of hHSCs from cord blood represented a major improvement to develop the continuous culture system for Plasmodium vivax. Here, we demonstrated that CD34+hHSCs from peripheral blood and bone marrow can be expanded and differentiated to reticulocytes using a novel stromal cell. Moreover, these reticulocytes and mature red blood cells express surface markers for entrance of malaria parasites contain adult haemoglobin and are also permissive to invasion by P. vivax and Plasmodium falciparum parasites.

Phospholipase gene expression during Paracoccidioides brasiliensis morphological transition and infection

Phospholipase is an important virulence factor for pathogenic fungi. In this study, we demonstrate the following: (i) the Paracoccidioides brasiliensis pld gene is preferentially expressed in mycelium cells, (ii) the plb1 gene is mostly up-regulated by infection after 6 h of co-infection of MH-S cells or during BALB/c mice lung infection, (iii) during lung infection, plb1, plc and pld gene expression are significantly increased 6-48 h post-infection compared to 56 days after infection, strongly suggesting that phospholipases play a role in the early events of infection, but not during the chronic stages of pulmonary infection by P. brasiliensis.

Influence of age on the haemoglobin concentration of malaria-infected patients in a reference centre in the Brazilian Amazon

Anaemia is amongst the major complications of malaria, a major public health problem in the Amazon Region in Latin America. We examined the haemoglobin (Hb) concentrations of malaria-infected patients and compared it to that of malaria-negative febrile patients and afebrile controls. The haematological parameters of febrile patients who had a thick-blood-smear performed at an infectious diseases reference centre of the Brazilian Amazon between December 2009-January 2012 were retrieved together with clinical data. An afebrile community control group was composed from a survey performed in a malaria-endemic area. Hb concentrations and anaemia prevalence were analysed according to clinical-epidemiological status and demographic characteristics. In total, 7,831 observations were included. Patients with Plasmodium falciparum infection had lower mean Hb concentrations (10.5 g/dL) followed by P. vivax-infected individuals (12.4 g/dL), community controls (12.8 g/dL) and malaria-negative febrile patients (13.1 g/dL) (p < 0.001). Age, gender and clinical-epidemiological status were strong independent predictors for both outcomes. Amongst malaria-infected individuals, women in the reproductive age had considerably lower Hb concentrations. In this moderate transmission intensity setting, both vivax and falciparum malaria are associated with reduced Hb concentrations and risk of anaemia throughout a wide age range.

Impact of a gall midge Parkiamyia paraensis (Diptera, Cecidomyiidae) on the Amazonian plant Parkia pendula (Fabaceae)

We observed the occurrence of large numbers of galls induced by Parkiamyia paraensis (Diptera, Cecidomyiidae) on the leaflets of Parkia pendula (Fabaceae) in northern Para, Brazil. We addressed two questions in this study: i) what is the proportion of attacked plants in the field, and nursery conditions?; and ii) what is the impact of galls on the host plant? An average of 86% of the plants were galled in the field. Galled P. pendula were distinct from healthy individuals due to their prostrated architecture and death of terminal shoots. Approximately 50% of the total available leaves and 35% leaflets were attacked by P. paraensis on saplings under nursery conditions. Each one-year old plant supported an average of 1,300 galls, and an average of 60g allocated to galled tissue. Otherwise, attacked individuals were taller and heavier than healthy plants. Attacked plants weighed five times more than healthy plants. When the weight of the galls was removed, the total weight (aerial part without galls) of attacked plants was drastically reduced, indicating that most of the biomass of attacked plants was due to the attack by P. paraensis galls. Although the data indicate a paradox, as young plants attacked by the galling herbivore appear to develop more vigorously than unattacked plants, we suggest that P. paraensis negatively affect P. pendula development.

Analysis of digestive tract content of the larvae of Polybia scutellaris (White) (Hymenoptera, Vespidae)

Polybia scutellaris (White, 1841) is a social wasp of biological interest for its role as pollinator and maybe as biological control agent of sanitary and agricultural pests. This study examines the digestive tract contents of the larvae of P. scutellaris from four nests in Magdalena (Buenos Aires province, Argentina). Contents included both animal (arthropod parts) and plant (pollen, leaf and fruit epidermis) parts. The pollen content analysis showed that the wasps visited 19 different taxa of plants during the last active period of the colony before the nests had been collected. The range of sources used by P. scutellaris allows us characterizing the species as a generalist flower visitor. Wasps visited both native and exotic plants located nearby the nest. Most of the epidermal plant remains found in the larval digestive tract belonged to Malvaceae, a family not exploited by the studied colonies as pollen source.

Effects of arbuscular mycorrhizal fungi and phosphorus fertilization on post vitro growth of micropropagated Zingiber officinale roscoe

The rhizomes of Zingiber officinale Roscoe (ginger) are widely used for their medicinal and flavoring properties, whereas the influence of root symbionts on their growth is poorly understood. In this study, the effects of phosphate fertilization and inoculation with a mixture of arbuscular mycorrhizal fungi (AMF) (isolates Glomus clarum RGS101A, Entrophospora colombiana SCT115A and Acaulospora koskei SPL102A) on survival, growth and development of micropropagated ginger were investigated. After transplanting to post vitro conditions, the ginger microplants were subjected to the following treatments: a) AMF mixture, b) P addition (25 mg kg-1), c) AMF + P, and d) non-mycorrhizal control without P addition. After eight months of growth, survival ranged from 86 to 100 % in the AMF and AMF+P treatments versus 71 % survival in control and P treatments. In the AMF, P and AMF+P treatments, the shoot, root and rhizome biomass production were significantly larger than in the control plants. In the non-mycorrhizal control plants the leaf number, leaf area, number of shoots/plants, and shoot length were significantly lower than in the AMF, P and AMF+P treatments. Root colonization ranged from 81 to 93 % and was not affected by P application. The data confirmed the response of several growth variables of micropropagated ginger to mycorrhizal colonization and P addition.

Mobility of inorganic and organic phosphorus forms under different levels of phosphate and poultry litter fertilization in soils

The eutrophication of aquifers is strongly linked to the mobility of P in soils. Although P mobility was considered irrelevant in a more distant past, more recent studies have shown that P, both in organic (Po) and inorganic forms (Pi), can be lost by leaching and eluviation through the soil profile, particularly in less weathered and/or sandier soils with low P adsorption capacity. The purpose of this study was to determine losses of P forms by leaching and eluviation from soil columns. Each column consisted of five PVC rings (diameter 5 cm, height 10 cm), filled with two soil types: a clayey Red-Yellow Latosol and a sandy loam Red-Yellow Latosol, which were exposed to water percolation. The soils were previously treated with four P rates (as KH2PO4 ) to reach 0, 12.5, 25.0 and 50 % of the maximum P adsorption capacity (MPAC). The P source was homogenized with the whole soil volume and incubated for 60 days. After this period the soils were placed in the columns; the soil of the top ring was mixed with five poultry litter rates of 0, 20, 40, 80, and 160 t ha-1 (dry weight basis). Treatments consisted of a 4 x 5 x 2 factorial scheme corresponding to four MPAC levels, five poultry litter rates, two soils, with three replications, arranged in a completely randomized block design. Deionized water was percolated through the columns 10 times in 35 days to simulate about 1,200 mm rainfall. In the leachate of each column the inorganic P (reactive P, Pi) and organic P forms (unreactive P, Po) were determined. At the end of the experiment, the columns were disassembled and P was extracted with the extractants Mehlich-1 (HCl 0.05 mol L-1 and H2SO4 0.0125 mol L-1) and Olsen (NaHCO3 0.5 mol L-1; pH 8.5) from the soil of each ring. The Pi and Po fractions were measured by the Olsen extractant. It was found that under higher poultry litter rates the losses of unreactive P (Po) were 6.4 times higher than of reactive P (Pi). Both the previous P fertilization and increasing poultry litter rates caused a vertical movement of P down the soil columns, as verified by P concentrations extracted by Mehlich-1 and NaHCO3 (Olsen). The environmental critical level (ECL), i.e., the P soil concentration above which P leaching increases exponentially, was 100 and 150 mg dm-3 by Mehlich-1 and 40 and 60 mg dm-3 by Olsen, for the sandy loam and clay soils, respectively. In highly weathered soils, where residual P is accumulated by successive crops, P leaching through the profile can be significant, particularly when poultry litter is applied as fertilizer.

Nutrition, dry matter accumulation and partitioning and phosphorus use efficiency of potato grown at different phosphorus levels in nutrient solution

High rates of phosphate fertilizers are applied to potato (Solanum tuberosum L.), which may cause antagonistic interactions with other nutrients and limit crop yields when over-supplied. The purpose of this study was to evaluate the influence of phosphorus (P) levels in nutrient solution on P use efficiency, nutritional status and dry matter (DM) accumulation and partitioning of potato plants cv. Ágata. The experiment was carried out in a greenhouse, arranged in a completely randomized block design with four replications. Treatments consisted of seven P levels in nutrient solution (0, 2, 4, 8, 16, 31, and 48 mg L-1). Plants were harvested after 28 days of growth in nutrient solution, and separated in roots, stems and leaves for evaluations. The treatment effects were analyzed by regression analysis. Phosphorus levels of up to 8 mg L-1 increased the root and shoot DM accumulation, but drastically decreased the root/shoot ratio of potato cv. Ágata. Higher P availability increased P concentration, accumulation and absorption efficiency, but decreased P use efficiency. Higher P levels increased the N, P, Mg, Fe, and Mn concentrations in roots considerably and decreased K, S, Cu, and Zn concentrations. In shoot biomass, N, P, K, and Ca concentrations were significantly increased by P applied in solution, unlike Mg and Cu concentrations. Although higher P levels (> 8 mg L-1) in nutrient solution increased P concentration, accumulation and absorption efficiency, the DM accumulation and partitioning of potato cv. Ágata were not affected.

Cinética e caracterização de ramnolipídeos produzidos por Pseudomonas aeruginosa MSIC02 utilizando glicerol como fonte de carbono

Glycerol, a co-product of biodiesel production, was used as a carbon source for the kinetics studies and production of biosurfactants by P. aeruginosa MSIC02. The highest fermentative parameters (Y PX = 3.04 g g-1; Y PS = 0.189 g g-1, P B = 31.94 mg L-1 h-1 and P X = 10.5 mg L-1 h-1) were obtained at concentrations of 0.4% (w/v) NaNO3 and 2% (w/v) glycerol. The rhamnolipid exhibited 80% of emulsification on kerosene, surface tension of 32.5 mN m-1, CMC = 28.2 mg L-1, C20 (concentration of surfactant in the bulk phase that produces a reduction of 20 dyn/cm in the surface tension of the solvent) = 0.99 mg L-1, Γm (surface concentration excess) = 2.4 x 10-26 mol Å-2 and S (surface area) = 70.4 Ų molecule-1 with solutions containing 10% NaCl. A mathematical model based on logistic equation was considered to representing the process. Model parameters were estimated by non-linear regression method. This approach was able to give a good description of the process.

Biodegradação bacteriana de compostos organoclorados

Due to their recalcitrant nature, organochlorides are already found in environment and the search for alternatives to eliminate these compounds such as biodegradation using native microorganisms is of great interest. A screening trial to select environmental bacteria able to degrade DDD, PCP and dieldrin was conducted. Among 14 isolates, the soil bacteria Pseudomonas aeruginosa L2-1 showed the highest tolerance to increasing concentrations of the organochlorides and was selected for further studies. Biodegradation was assessed in liquid medium, varying the concentrations of glucose and the presence of rhamnolipids (RL). The best medium for the occurrence of biodegradation of the compounds contained 0.5% glucose, giving approximately 50% yield after three days of incubation. Results showed that the biodegradation rates of the organochlorides by P. aeruginosa L2-1 were greater at low concentrations of glucose and in the presence of rhamnolipids.