Project description:Artemisinin resistance in Plasmodium falciparum malaria has emerged in western Cambodia. This is a major threat to global plans to control and eliminate malaria as the artemisinins are a key component of antimalarial treatment throughout the world. Using DNA microarrays we identify key features of a transcriptional profile that are associated with the delayed parasite clearance phenotype. These include reduced expression of several basic metabolic and cellular pathways in the early stages, and increased expression of essentially all functionalities associated with protein metabolism in the later stages of P. falciparum intraerythrocytic development. This is consistent with the reduced ring stage susceptibility that characterizes artemisinin resistant P. falciparum. This modulation of the P. falciparum intraerythrocytic transcriptome may result from differential expression of several regulatory proteins such as transcription factors of chromatin remodeling associated factors. In addition, the artemisinin resistant phenotype is strongly associated with a specific pattern of copy number variations, some of which are linked with differential expression of several regulatory proteins such as histone 4 and zinc permease. This study reports the first global transcriptional survey of artemisinin resistant parasites and provides a set of candidate genes for further investigation. 6 P. falciparum parasites (field isolates) which are either Artemsinin resistant or sensitive from 3 study sites (Pailin in Cambodia, Xepon in Laos, Mae Sot in Thailand) were sampled and harvested for genomic DNA. gDNA from a total of 6 samples were extracted by phenol chloroform. Synthesis of labelled target DNA was carried out as previously described: Mackinnon, M.J. et al. Comparative transcriptional and genomic analysis of Plasmodium falciparum field isolates. PLoS Pathog 5, e1000644 (2009), and used in comparative genomic microarray hybridizations (CGH).
Project description:Artemisinin resistance in Plasmodium falciparum malaria has emerged in western Cambodia. This is a major threat to global plans to control and eliminate malaria as the artemisinins are a key component of antimalarial treatment throughout the world. Using DNA microarrays we identify key features of a transcriptional profile that are associated with the delayed parasite clearance phenotype. These include reduced expression of several basic metabolic and cellular pathways in the early stages, and increased expression of essentially all functionalities associated with protein metabolism in the later stages of P. falciparum intraerythrocytic development. This is consistent with the reduced ring stage susceptibility that characterizes artemisinin resistant P. falciparum. This modulation of the P. falciparum intraerythrocytic transcriptome may result from differential expression of several regulatory proteins such as transcription factors of chromatin remodeling associated factors. In addition, the artemisinin resistant phenotype is strongly associated with a specific pattern of copy number variations, some of which are linked with differential expression of several regulatory proteins such as histone 4 and zinc permease. This study reports the first global transcriptional survey of artemisinin resistant parasites and provides a set of candidate genes for further investigation. 11 P. falciparum parasites (field isolates) which are either Artemsinin resistant or sensitive from 3 study sites (Pailin in Cambodia, Xepon in Laos, Mae Sot in Thailand) were sampled, grown ex-vivo over 48 hours and harvested at regular intervals. RNA from a total of 91 samples were extracted. Synthesis of target DNA was carried out as previously described: Mackinnon, M.J. et al. Comparative transcriptional and genomic analysis of Plasmodium falciparum field isolates. PLoS Pathog 5, e1000644 (2009), and used in microarray hybridizations.
Project description:Hypoglycemia is a clinical hallmark of severe malaria, the often-lethal outcome of Plasmodium falciparum infection. Yet, the underlying mechanisms driving the pathogenesis of malaria-associated hypoglycemia remain poorly understood. Here we report that labile heme, an alarmin generated as a byproduct of hemolysis during the blood stage of Plasmodium spp. infection, plays a central role in the development of malaria-associated hypoglycemia. Labile heme recapitulated the hypometabolic response to Plasmodium (chabaudi chabaudi; Pcc) infection in mice, including the development of anorexia, transcriptional repression of hepatic glucose production (HGP) and reduction of glycemia, energy expenditure (EE) as well as core body temperature. While this hypometabolic response is protective against immune-mediated liver damage and anemia, when sustained over time it can lead to hypoglycemia and compromise EE as well as thermoregulation. In response, asexual stages of Plasmodium spp. activate a transcriptional program that reduces virulence in favor of sexual commitment and presumably malaria transmission. In conclusion, malaria-associated hypoglycemia represents a trade-off of a hypometabolic defense strategy against Plasmodium infection.
Project description:Hypoglycemia is a clinical hallmark of severe malaria, the often-lethal outcome of Plasmodium falciparum infection. Yet, the underlying mechanisms driving the pathogenesis of malaria-associated hypoglycemia remain poorly understood. Here we report that labile heme, an alarmin generated as a byproduct of hemolysis during the blood stage of Plasmodium spp. infection, plays a central role in the development of malaria-associated hypoglycemia. Labile heme recapitulated the hypometabolic response to Plasmodium (chabaudi chabaudi; Pcc) infection in mice, including the development of anorexia, transcriptional repression of hepatic glucose production (HGP) and reduction of glycemia, energy expenditure (EE) as well as core body temperature. While this hypometabolic response is protective against immune-mediated liver damage and anemia, when sustained over time it can lead to hypoglycemia and compromise EE as well as thermoregulation. I response, asexual stages of Plasmodium spp. activate a transcriptional program that reduces virulence in favor of sexual commitment and presumably malaria transmission. In conclusion, malaria-associated hypoglycemia represents a trade-off of a hypometabolic defense strategy against Plasmodium infection.
Project description:Sugarcane (Saccharum hybrid, SP80-3280) was grown in the field in Araras (Brazil) for 9 months. Leaves +1 (F1), internodes 1&2 (I1), and internodes 5 (I5) were harvested every 2 h for 26 h, starting 2h before dawn.
Project description:A field experiment was conducted at the Federal University of Alagoas in Maceio, Brazil. varieties RB86-7515, RB85-5536 and RB92-579 were distributed in a randomized block design with four replicates in two conditions: irrigated (control) and non-irrigated (treatment).