Plasmodium cynomolgi, a malaria parasite of Asian Old World monkeys, is the sister taxon of Plasmodium vivax, the most prevalent human malaria species outside Africa. Since P. cynomolgi shares many phenotypic, biologic and genetic characteristics of P. vivax, we generated draft genome sequences of three P. cynomolgi strains and performed comparative genomic analysis between them and P. vivax, as well as a third previously sequenced simian parasite, Plasmodium knowlesi. Here we show that genomes of the monkey malaria clade can be characterized by CNVs in multigene families involved in evasion of the human immune system and invasion of host erythrocytes. We identify genome-wide SNPs, microsatellites, and CNVs in the P. cynomolgi genome, providing a map of genetic variation for mapping parasite traits and studying parasite populations. The P. cynomolgi genome is a critical step in developing a model system for P. vivax research, and to counteract the neglect of P. vivax.
Photoperiod is a major factor in the induction of pupal diapause in the ovoviviparaous flesh fly, Sarcophaga similis. This species entered diapause when kept under short-day conditions throughout the embryonic and larval stages. Exposure to long-day conditions for the whole embryonic or whole larval stage, however, prevented diapause. Moreover, most insects did not enter diapause when they were exposed to long-day conditions for only 2 days in the embryonic stage just before larviposition. When the uterus containing embryos was removed from the mother's body and kept in vitro under long-day conditions, most of these embryos became nondiapause pupae even under subsequent short-day conditions. When postfeeding larvae were exposed to long-day conditions for 3 days, 50% entered diapause. From these results, it is concluded that sensitivity to photoperiod is highest in the later embryonic stage and embryonic sensitivity to photoperiod is independent of the mother.
Understanding the transmission and movement of Plasmodium parasites is crucial for malaria elimination and prevention of resurgence. Located at the limit of malaria transmission in the Pacific, Vanuatu is an ideal candidate for elimination programs due to low endemicity and the isolated nature of its island setting. We analyzed the variation in the merozoite surface protein 1 (msp1) and the circumsporozoite protein (csp) of P. falciparum and P. vivax populations to examine the patterns of gene flow and population structures among seven sites on five islands in Vanuatu. Genetic diversity was in general higher in P. vivax than P. falciparum from the same site. In P. vivax, high genetic diversity was likely maintained by greater extent of gene flow among sites and among islands. Consistent with the different patterns of gene flow, the proportion of genetic variance found among islands was substantially higher in P. falciparum (28.81–31.23%) than in P. vivax (-0.53–3.99%). Our data suggest that the current island-by-island malaria elimination strategy in Vanuatu, while adequate for P. falciparum elimination, might need to be complemented with more centrally integrated measures to control P. vivax movement across islands.
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