title: Refrigeration provides a simple means to synchronize in vitro cultures of Plasmodium falciparum.
abstract: Plasmodium falciparum is usually asynchronous during in vitro culture. Highly synchronized cultures of P. falciparum are routinely used in malaria research. Here, we describe a simple synchronization procedure for P. falciparum asexual erythrocytic culture, which involves storage at 4°C for 8-24 h followed by routine culture. When cultures with 27-60% of ring stage were synchronized using this procedure, 70-93% ring stages were obtained after 48 h of culture and relative growth synchrony remained for at least two erythrocytic cycles. To test the suitability of this procedure for subsequent work, drug sensitivity assays were performed using four laboratory strains and four freshly adapted clinical P. falciparum isolates. Parasites synchronized by sorbitol treatment or refrigeration showed similar dose-response curves and comparable IC50 values to four antimalarial drugs. The refrigeration synchronization method is simple, inexpensive, time-saving, and should be especially useful when large numbers of P. falciparum culture are handled.
authors.affiliation: Department of Pathogen Biology and Immunology, Kunming Medical University, Yunnan Province 650500, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Department of Pathogen Biology and Immunology, Kunming Medical University, Yunnan Province 650500, China.
authors.forename: Mingming
authors.initials: M
authors.lastname: Hao
authors.affiliation: Department of Pharmacology, Kunming Medical University, Yunnan Province 650500, China.
authors.forename: Lanou
authors.initials: L
authors.lastname: Wu
authors.affiliation: Department of Pathogen Biology and Immunology, Kunming Medical University, Yunnan Province 650500, China; Department of Pharmacology, Kunming Medical University, Yunnan Province 650500, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Animal Parasitic Disease Laboratory, Agricultural Research Service, US Department of Agriculture, BARC East Building 1180, Beltsville, MD 20705, USA.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Rosenthal
authors.affiliation: School of Public Health, Kunming Medical University, Yunnan Province 650500, China.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Cell Biology and Genetics, Kunming Medical University, Yunnan Province 650500, China.
authors.forename: Yongshu
authors.initials: Y
authors.lastname: He
authors.affiliation: Department of Pathogen Biology and Immunology, Kunming Medical University, Yunnan Province 650500, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Sun
authors.affiliation: Center for Biomedical Engineering Research, Kunming Medical University, Yunnan Province 650500, China.
authors.forename: Guohua
authors.initials: G
authors.lastname: Feng
authors.affiliation: Department of Pathogen Biology and Immunology, Kunming Medical University, Yunnan Province 650500, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Xiang
authors.affiliation: Department of Entomology, The Pennsylvania State University, 501 ASI Building, University Park, PA 16802, USA. Electronic address: luc2@psu.edu.
authors.forename: Liwang
authors.initials: L
authors.lastname: Cui
authors.affiliation: Department of Pharmacology, Kunming Medical University, Yunnan Province 650500, China. Electronic address: zhaoqingy@yahoo.com.
authors.forename: Zhaoqing
authors.initials: Z
authors.lastname: Yang
mesh_terms: D000962:Antimalarials / Q000494:pharmacology; D003080:Cold Temperature; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000469:parasitology; D007202:Indicators and Reagents; D020128:Inhibitory Concentration 50; D021261:Parasitic Sensitivity Tests / Q000379:methods*; D010963:Plasmodium falciparum / Q000187:drug effects / Q000254:growth & development*; D012034:Refrigeration; D013012:Sorbitol
chemical_list: D000962:Antimalarials; D007202:Indicators and Reagents; D013012:Sorbitol
keywords: Drug susceptibility; Plasmodium falciparum; Refrigeration; Synchronization