BackgroundSevere anaemia is a common complication of Plasmodium falciparum malaria in hyperendemic regions. Premature elimination of non-parasitized red blood cells (nRBC) has been considered as one mechanism involved in the genesis of severe malaria anaemia. It has been reported that apoptosis can occur in RBC and, consequently, this cell death process could contribute to anaemia. This study was performed to evaluate the susceptibility of nRBC to apoptosis in a malaria anaemia murine model.MethodsBalb/c mice were intraperitonially inoculated with 1 × 106 P. yoelii 17XL parasitized RBC (pRBC) and, then, parasitaemia and anaemia were monitored. Apoptosis in both pRBC and nRBC was assessed during early and late phases of infection by flow cytometry using Syto 16 and annexin V-PE double staining and forward scatter measurement.ResultsAs expected, experimental infection of Balb/c mice with Plasmodium yoelii 17XL parasites was characterized by progressive increase of parasitaemia and acute anaemia, leading to death. Flow cytometry analysis showed that a number of pRBC was in the apoptotic process. It was noteworthy that the increase of nRBC apoptosis levels occurred in the late phase of infection, when anaemia degree was notably accentuated, while no significant alteration was observed in the early phase.ConclusionThe increased levels of nRBC apoptosis herein firstly reported, in malaria infection could represent a putative mechanism worsening the severity of malarial anaemia.

Letras minúsculas diferentes -diferença significativa entre os grupos expostos no mesmo intervalo de tempo. Letras maiúsculas diferentes -diferença significativa entre o grupo exposto nos diferentes intervalos de tempo. dias 30 dias 45 diasControle 6,523 ± 1,189ª ,A 3,101 ± 0,383ª ,B 2,912 ± 0,3603 a,B 20mg CaCO 3 3,190 ± 1,047 b,A 2,383 ± 0,825ª ,b,B 1,499 ± 0,761 a,B

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BackgroundApoptosis can occur in red blood cells (RBC) and seems to be involved in hematologic disorders related to many diseases. In malaria it is known that parasitized RBC (pRBC) is involved in the development of anemia and thrombosis; however, non-parasitized RBC (nRBC) apoptosis could amplify these malaria-associated hematologic events. In fact, in experimental malaria, increased levels of apoptosis were observed in nRBC during lethal Plasmodium yoelii 17XL infection, but in human malaria erythrocytic apoptosis has never been studied. The present study was performed to investigate if nRBC apoptosis also occurs in P. vivax and P. falciparum infections.FindingsApoptosis of nRBC was evaluated in blood samples of P. vivax malaria patients and clinically healthly individuals living in Manaus, Brazil, both ex vivo and after incubation of RBC for 24 h. Additionally, the capacity of plasma from P. vivax or P. falciparum patients was tested for induction of in vitro apoptosis of normal RBC from a clinically healthy individual living in a non-endemic malaria region. Apoptosis was detected by flow cytometry using annexin V staining. In contrast to experimental malaria that significantly increased the levels of apoptotic nRBC both ex-vivo and after 24 h of incubation, no significant alteration on apoptotic nRBC rates was detected in P. vivax infected patients when compared with non-infected control individuals. Similar results were observed when plasma of these P. vivax patients was incubated with normal RBC. Conversely, plasma from P. falciparum-infected subjects induced significant apoptosis of these cells.ConclusionsApoptosis of normal RBC can be induced by plasma from individuals with P. falciparum (but not with P. vivax) malaria. This finding could reflect the existence of erythrocytic apoptosis during infection that could contribute to the pathogenesis of hematological and vascular complications associated with falciparum malaria.

Background: Apoptosis can occur in red blood cells (RBC) and seems to be involved in hematologic disorders related to many diseases. In malaria it is known that parasitized RBC (pRBC) is involved in the development of anemia and thrombosis; however, non-parasitized RBC (nRBC) apoptosis could amplify these malaria-associated hematologic events. In fact, in experimental malaria, increased levels of apoptosis were observed in nRBC during lethal Plasmodium yoelii 17XL infection, but in human malaria erythrocytic apoptosis has never been studied. The present study was performed to investigate if nRBC apoptosis also occurs in P. vivax and P. falciparum infections. Findings: Apoptosis of nRBC was evaluated in blood samples of P. vivax malaria patients and clinically healthly individuals living in Manaus, Brazil, both ex vivo and after incubation of RBC for 24 h. Additionally, the capacity of plasma from P. vivax or P. falciparum patients was tested for induction of in vitro apoptosis of normal RBC from a clinically healthy individual living in a non-endemic malaria region. Apoptosis was detected by flow cytometry using annexin V staining. In contrast to experimental malaria that significantly increased the levels of apoptotic nRBC both ex-vivo and after 24 h of incubation, no significant alteration on apoptotic nRBC rates was detected in P. vivax infected patients when compared with non-infected control individuals. Similar results were observed when plasma of these P. vivax patients was incubated with normal RBC. Conversely, plasma from P. falciparum-infected subjects induced significant apoptosis of these cells. Conclusions: Apoptosis of normal RBC can be induced by plasma from individuals with P. falciparum (but not with P. vivax) malaria. This finding could reflect the existence of erythrocytic apoptosis during infection that could contribute to the pathogenesis of hematological and vascular complications associated with falciparum malaria.

Adequate pasture management is important to ensure animal production. The objective of this study was to evaluate the effect on shoot dry weight yield (SDWY) and mineral composition in degraded pasture (Urochloa decumbens) recovery in a Typic Oxisol with introduction of Stylosanthes and phosphorus (P) fertilization. The experiment was set up as completely randomized block design in a split-plot arrangement with four replicates. The plots were seven management system: T1 - Control Urochloa decumbens without Stylosanthes; T2 - U. decumbens + Stylosanthes with no-till; T3 - U. decumbens with partial desiccation + Stylosanthes; T4 - U. decumbens with total desiccation + Stylosanthes; T5 - U. decumbens + Stylosanthes with soil scarification; T6 - U. decumbens + Stylosanthes with plowing;  T7 - U. decumbens + Stylosanthes with plowing + harrowing and the subplots was the P fertilization (presence and absence). P fertilization (60 kg ha-1 of P2O5) increased the P concentration and SDWY of U. decumbens, while the introduction of Stylosanthes in the different management systems used did not change the forage yield.

Sabe-se que o sistema radicular do algodoeiro se situa predominantemente na região compreendida pelos primeiros 20 cm de profundidade do solo. Como a cultura exige intensas práticas culturais, torna-se útil conhecer a distribuição progressiva do sistema radicular naquela região, sobretudo nos primeiros meses do ciclo vegetative época em que a cultura exige a intensificação das capinas. Estudos sôbre a questão foram efetuados em um ensaio de campo com a variedade IAC 12-57/566, em solo tipo terra-roxa-misturado, fozendo-se observações aos 42, 61 e 81 dias após a germinação das sementes. Os dados mostraram maior concentração de raízes na camada de 3 a 15 cm de profundidade do solo e até a uma distância aproximada de 25 cm lateralmente às plantas. O ritmo de crescimento do sistema radicular do algodoeiro foi mais intenso do 42.° ao 61.° dia após a germinação. A má utilização dos implementos agrícolas nesse período mais critico, poderá pois, provocar grandes danos à cultura, principalmente se forem empregados cultivos profundos.

The aim of this study was to evaluate the influence of population density and food intake on the survival and reproduction of uninfected Biomphalaria glabrata and the effect of calcium carbonate availability on cercarial emergence from experimentally infected snails, to define conditions to maximize snails' breeding and cercarial production for future studies about this model. The results observed in this study indicate that increased population density has a negative effect on the survival and reproductive activity of B. glabrata. In addition, the quantity of lettuce offered to the snails altered the number of eggs laid per snail. There was a significant relation between the amount of lettuce eaten per day and the number of eggs produced per snail, as well as the number of egg masses per snail, and eggs per egg mass. Furthermore, the snail's survival was directly associated with the amount of calcium carbonate and the cercarial emergence was inversely related to the calcium carbonate amount. This study might help to understand the influence of population density and food intake on the reproductive biology of captive snail populations. In relation to cercarial emergence, calcium supplies must not be provided to Schistosoma mansoni-infected snails while maintaining S. mansoni under laboratory conditions because it decreases cercarial emergence.