In-vitro uptake of vitamin A by Plasmodium falciparum.
The vitamin-A uptake of Plasmodium falciparum was investigated by culturing a standard isolate of the parasite (FCR-3) with (3)H-labelled vitamin A, at concentrations of the vitamin corresponding to those normally present in human serum. The (3)H-labelled vitamin A accumulated in the parasites from each culture in a parasitaemia-dependent manner. The radioactivity detected in the parasites increased with parasite maturation from the ring to the late-trophozoite stage. In addition, most of the radioactivity incorporated into the parasite cells was in the cytoplasm. The accumulation of vitamin A in the cytoplasm of late trophozoites indicates that P. falciparum may use vitamin A, from its human host, as an antioxidant, to protect itself from oxidative stress while intra-erythrocytic. The amount of the vitamin taken up by the parasite in vitro is small compared with the deficit that sometimes causes severe hypovitaminosis A in malaria cases. Consumption of vitamin A by the parasites together with the systemic decreases in non-enzymatic antioxidants that are seen in malaria may together cause this characteristic hypovitaminosis.
Mizuno
Y
Y
Department of Paediatrics, Jikei University School of Medicine, 3-25-8, Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan. mizuno@jikei.ac.jp
Kawazu
S-I
SI
Kano
S
S
Watanabe
N
N
Matsuura
T
T
Ohtomo
H
H
D000818:Animals; D003470:Culture Media; D004912:Erythrocytes / Q000469:parasitology; D006801:Humans; D018512:Parasitemia / Q000469:parasitology; D010963:Plasmodium falciparum / Q000254:growth & development / Q000378:metabolism*; D013997:Time Factors; D014801:Vitamin A / Q000493:pharmacokinetics*; D014802:Vitamin A Deficiency / Q000469:parasitology
D003470:Culture Media; D014801:Vitamin A