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trials to infect anopheles stephensi with plasmodium yoelii nigeriensis by the membrane feeding technique.the aim of this study was to find optimal conditions for the membrane feeding technique to obtain maximum infection rates of mosquitoes with plasmodium yoelii nigeriensis. the results show that the malaria parasite plasmodium yoelii nigeriensis is most infective to anopheles stephensi mosquitoes on day 3 of the infection in the mice, 1 day before the peak of parasitaemia. the mortality rate of the mosquitoes fed on mice on day 3 after infection was the highest as compared to mosquitoes fed on ot ...19921456466
the effects of nosema algerae on the development of plasmodium yoelii nigeriensis in anopheles stephensi.experimental simultaneous infections of anopheles stephensi (diptera: culicidae) with nosema algerae (microsporida: nosematidae) and plasmodium yoelii nigeriensis under standardized laboratory conditions showed partial suppression of the malaria parasite. at 9 days after an infective bloodmeal, the oocysts in the midgut were counted; 12.1%-66.6% of the double-infected mosquitoes exhibited no oocysts, whereas only 4.5%-12% of the control group showed no oocysts. the mean reduction in oocyst numbe ...19921584748
plasmodium yoelii nigeriensis (n67) is a robust animal model to study malaria transmission by south american anopheline mosquitoes.malaria is endemic in the american continent and the amazonian rainforest is the region with the highest risk of transmission. however, the lack of suitable experimental models to infect malaria vectors from the americas has limited the progress to understand the biology of transmission in this region. anopheles aquasalis, a major vector in coastal areas of south america, was found to be highly refractory to infection with two strains of plasmodium falciparum (nf54 and 7g8) and with plasmodium b ...201627911924
malaria-induced apoptosis in mosquito ovaries: a mechanism to control vector egg production.many insects are able to adjust their egg production according to physiological conditions such as nutrient supply and mating success. one way in which this is achieved is by resorption of some, or all, of the ovarian follicles at some stage during oogenesis. we have shown that the mosquito anopheles stephensi responds in this manner when ookinetes of the malaria parasite plasmodium yoelii nigeriensis first begin to invade the midgut. little is known about the initiation and regulation of follic ...200111683433
blood digestion in the mosquito, anopheles stephensi: the effects of plasmodium yoelii nigeriensis on midgut enzyme activities.midgut proteases contribute to the success or failure of plasmodium infection of the mosquito. this paper examines the reciprocal effect of plasmodium yoelii nigeriensis on midgut trypsin, chymotrypsin, aminopeptidase and carboxypeptidase in the mosquito anopheles stephensi. the total protein ingested and the rate of protein digestion were unaffected by the parasite, but more protein was ingested at the first than the second bloodmeal. all peptidases were unaffected by the presence of the parasi ...199910633914
the effect of plasmodium yoelii nigeriensis infection on the feeding persistence of anopheles stephensi liston throughout the sporogonic cycle.vector-borne parasites such as malaria have been shown to modify the feeding behaviour of their invertebrate hosts so as to increase the probability of transmission. however, evolutionary consideration of developmental changes in malaria within anopheles mosquitoes suggests that the nature of altered feeding by mosquitoes should differ depending on the developmental stage of the parasite. we present laboratory evidence that the feeding persistence of female anopheles stephensi towards a human ho ...199910518321
effects of plasmodium yoelii nigeriensis infection on anopheles stephensi egg development and resorption.it has been shown previously that infection with plasmodium yoelii nigeriensis reduces the number of eggs produced by female anopheles stephensi. here we examine the mechanism underlying fecundity reduction. ovaries from infected and uninfected (control) female mosquitoes were examined 12, 24 or 36 h after blood-feeding during the first gonotrophic cycle (replicated) or the second gonotrophic cycle (unreplicated). follicular development was assessed according to christophers' stages and the prop ...19979330258
the effects of infection with plasmodium yoelii nigeriensis on the reproductive fitness of anopheles stephensi.infection with the rodent malarial parasite plasmodium yoelii nigeriensis caused a significant reduction in the reproductive fitness (number of eggs produced and proportion of eggs hatched) of two different generations of anopheles stephensi. overall fertility (number of larvae produced) was reduced by 38.3% in the generation containing smaller mosquitoes (with a wing length of 3.2 +/- 0.1 mm) with relatively larger parasite burdens, and by 48.81% in the generation containing larger mosquitoes ( ...19979290843
the effect of plasmodium yoelii nigeriensis infection on ovarian protein accumulation by anopheles stephensi.both anopheline and culicine mosquitoes have been shown to incur a reduction in reproductive fitness when infected with malaria parasites. the agent of rodent malaria, plasmodium yoelii nigeriensis, was used as a laboratory model to investigate changes in the accumulation of protein in the ovaries of anopheles stephensi when infected with oocysts or when feeding on mice with heavy asexual parasitaemia but no mature gametocytes. herein we report that during the early phases of the gonotrophic cyc ...19979134561
plasmodium yoelii nigeriensis: the effect of high and low intensity of infection upon the egg production and bloodmeal size of anopheles stephensi during three gonotrophic cycles.anopheles stephensi mosquitoes showed a reduction in fecundity over 3 successive gonotrophic cycles, after becoming infected with plasmodium yoelii nigeriensis. this effect could be observed at high oocyst burdens (> 75) or at low oocyst burdens (mean of 4.36). mean bloodmeal size of the infected mosquitoes was significantly reduced only when feeding upon a mouse with a high gametocytaemia and the conversion of the bloodmeal into eggs by the infected mosquitoes was disrupted. patterns of infecte ...19958559587
malaria-induced reduction of fecundity during the first gonotrophic cycle of anopheles stephensi mosquitoes.anopheles stephensi mosquitoes which had fed upon mice infected with plasmodium yoelii nigeriensis malaria parasites produced significantly fewer eggs than mosquitoes fed on an uninfected mouse. fecundity reduction was more pronounced when the bloodmeal contained malaria gametocytes and the mosquitoes developed oocysts. egg production and haematin excretion were correlated for uninfected bloodfed mosquitoes; the presence of p.y.nigeriensis in the blood affected this relationship. reduced fecundi ...19957787226
vaccination to prevent transmission of plasmodium yoelii malaria.it was possible to block the transmission of infection of the rodent malaria parasite plasmodium yoelii nigeriensis to anopheles stephensi mosquitoes by immunizing mice with a vaccine containing formalin-fixed gametes. both intramuscular and intravenous routes were effective, immunity was achieved with a single dose and the immunity persisted for 6 months at least. transmission-blocking immunity was found to reside in a serum factor, probably antibody, and to be directed against extracellular ga ...19827070834
[inhibition of the infectivity of plasmodium gametocytes by the serum of the parasite host. perfecting an experimental model].in the course of experimental malarial infections the infectivity of the gametocytes falls abruptly and at an early stage of the infection. this phenomenon is independent of the production of circulating antibodies. with plasmodium yoelii nigeriensis infecting the white mouse, the maximum infectivity of gametocytes for anopheles stephensi occurs on day 2, and on day 5 no more oocysts develop in the mosquito. the behaviour of the plasmodial strain in the mouse and particularly the "crisis" phenom ...19873662325
[ultrastructural study on effect of primaquine on sporogonic stage of plasmodium yoelii nigeriensis].ultrastructural changes of oocysts and sporozoites of plasmodium yoelii nigeriensis was observed. anopheles stephensi were allowed to obtain blood meal from the mice which had been administered with primaquine diphosphate at different doses and times. mosquitoes were directed and prepared 6-13 d following infection. electron microscopy showed that the development and morphology of a number of oocysts and sporozoites in infected mosquitoes after treatment became abnormal. the cytoplasma of the oo ...19892610001
larval nutrition differentially affects adult fitness and plasmodium development in the malaria vectors anopheles gambiae and anopheles stephensi.mosquito fitness is determined largely by body size and nutritional reserves. plasmodium infections in the mosquito and resultant transmission of malaria parasites might be compromised by the vector's nutritional status. we studied the effects of nutritional stress and malaria parasite infections on transmission fitness of anopheles mosquitoes.201324326030
effect of chloroquine on gene expression of plasmodium yoelii nigeriensis during its sporogonic development in the mosquito vector.the anti-malarial chloroquine can modulate the outcome of infection during the plasmodium sporogonic development, interfering with plasmodium gene expression and subsequently, with transmission. the present study sets to identify plasmodium genes that might be regulated by chloroquine in the mosquito vector.200717605769
the influence of host haematocrit on the blood feeding success of anopheles stephensi: implications for enhanced malaria transmission.two studies were carried out to determine the effect of the rodent malaria plasmodium yoelii nigeriensis on the blood feeding success of anopheles stephensi. initially, pairs of mice with similar packed cell volume (pcv) (measured by haematocrit) were selected. following infection of one of the pair its pcv gradually fell. at various times post-infection, a comparison was made of the bloodmeal size (haemoglobin content) of mosquitoes feeding on these mice. the bloodmeal sizes increased with para ...200111393821
effect of plasmodium yoelii nigeriensis (haemosporidia: plasmodiidae) on anopheles stephensi (diptera: culicidae) vitellogenesis.our previous studies demonstrated a significant reduction in the egg production and survival of anopeles stephensi liston infected with plasmodium yoelii nigeriensis killick-kendrick. we investigated the physiological mechanism underlying the malaria-induced curtailment of reproductive fitness. polyclonal antibodies were raised against an. stephensi vitellin (vn) and used in an enzyme immunoassay to quantify ovarian vn and hemolymph vitellogenin (vg) at 8, 12, 16, 20, 24, and 48 h postblood feed ...19989835686
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