Kawamoto F, Kido N, Hanaichi T, Djamgoz M B, Sinden R E
Department of Medical Zoology, Nagoya University School of Medicine, Japan.
Parasitol Res. 1992;78(4):277-84. doi: 10.1007/BF00937084.
Ionic regulation in the induction of exflagellation of Plasmodium berghei was investigated by culturing the parasites in various isotonic media. Of the salts tested, NaHCO3 exhibited the highest activity in inducing exflagellation, whereas KHCO3 showed no activity. In the absence of HCO3-, media containing monovalent cation (Na+, K+, Cs+, Rd+, choline+, lysine+, arginine+) and Cl- also induced exflagellation, but their activities were lower than that of NaHCO3. Anions of Br- or NO3- could be substituted with Cl-, whereas other anions such as I-, NO2-, SO4(2-), SCN-, H2PO4-, or HPO4(2-) failed to induce exflagellation, as did tetramethylammonium-Cl, CaCl2, MgSO4, MgCl2 and sucrose as well. These results suggest that the induction of exflagellation requires the presence of Na+ and HCO3- or monovalent, membrane-permeable cation and Cl- in the medium. Measurements of the efflux of H[14C]O3- or Cl- indicated that these anions were released from the cells into the NaCl or the NaHCO3 medium, respectively, probably by exchange in HCO3-/Cl-. Determination of intracellular ionic concentrations by electron microscopic X-ray microanalysis of cryopreserved specimens revealed that in the NaHCO3 medium, external Na+ (and probably HCO3-) enters the gametocytes by exchange with internal Cl- (and probably H+), whereas in Cl(-)-containing media, external unspecified cation and Cl- influx by exchange, probably with H+ and HCO3-. It is therefore suggested that two separate ion exchangers, i.e., Na(+)-dependent HCO3-(in)/Cl-(out) and nonspecific monovalent-cation-dependent Cl-(in)/HCO3-(out) exchangers, are involved in the induction of gametogenesis in P. berghei.(ABSTRACT TRUNCATED AT 250 WORDS)
通过在各种等渗培养基中培养寄生虫，研究了伯氏疟原虫配子体出丝诱导过程中的离子调节。在所测试的盐中，NaHCO₃在诱导出丝方面表现出最高活性，而KHCO₃则无活性。在没有HCO₃⁻的情况下，含有单价阳离子（Na⁺、K⁺、Cs⁺、Rb⁺、胆碱⁺、赖氨酸⁺、精氨酸⁺）和Cl⁻的培养基也能诱导出丝，但其活性低于NaHCO₃。Br⁻或NO₃⁻阴离子可被Cl⁻替代，而其他阴离子如I⁻、NO₂⁻、SO₄²⁻、SCN⁻、H₂PO₄⁻或HPO₄²⁻以及四甲基氯化铵、CaCl₂、MgSO₄、MgCl₂和蔗糖均不能诱导出丝。这些结果表明，出丝诱导需要培养基中存在Na⁺和HCO₃⁻或单价、可透过膜的阳离子和Cl⁻。对H¹⁴CO₃⁻或Cl⁻外流的测量表明，这些阴离子分别从细胞释放到NaCl或NaHCO₃培养基中，可能是通过HCO₃⁻/Cl⁻交换。通过对冷冻保存标本的电子显微镜X射线微分析测定细胞内离子浓度表明，在NaHCO₃培养基中，外部Na⁺（可能还有HCO₃⁻）通过与内部Cl⁻（可能还有H⁺）交换进入配子体，而在含Cl⁻的培养基中，外部未指定的阳离子和Cl⁻通过与H⁺和HCO₃⁻交换流入。因此，有人提出，两个独立的离子交换体，即Na⁺依赖性HCO₃⁻（内）/Cl⁻（外）和非特异性单价阳离子依赖性Cl⁻（内）/HCO₃⁻（外）交换体，参与了伯氏疟原虫配子发生的诱导。（摘要截于250字）
