十二指肠贾第虫完整滋养体对L-[U¹⁴C-]天冬氨酸和L-[U¹⁴C-]丙氨酸的摄取及向¹⁴CO₂的转化

The uptake and conversion of L-[U14C-] aspartate and L-[U14C-] alanine to 14CO2 by intact trophozoites of Giardia duodenalis.

作者信息

Mendis A H, Thompson R C, Reynoldson J A, Armson A, Meloni B P, Gunsberg S

机构信息

School of Biomedical Sciences, Curtin University of Technology, Perth, Western Australia.

出版信息

Comp Biochem Physiol B. 1992 Jun;102(2):235-9. doi: 10.1016/0305-0491(92)90116-9.

DOI:10.1016/0305-0491(92)90116-9

Abstract

Intact trophozoites of Giardia duodenalis (clone P1C10) took up and metabolised L-[U14C-] aspartate to 14CO2 at rates of 10.27 +/- 0.76 and 27.6 +/- 2.07 ng hr-1 10(-6) cells in a simple maintenance medium (MM) and in a complex bile supplemented (BIS-33) medium respectively. 2. Intact trophozoite of G. duodenalis (clone P1C10) also took up and metabolised L-[U14C-] alanine to 14CO2 at rates of 20.6 +/- 1.1 and 91.4 +/- 17.5 ng hr-1 10(-6) cells in the simple (MM) and complex (BIS-33) medium respectively. 3. trophozoite sonicates contained significant levels of aspartate-2-oxoglutarate transaminase (AST; EC 2.6.1.1) and alanine-2-oxoglutarate transaminase (ALT; EC 2.6.2.2.). Specific activities (at 23 degrees C) were 95.1 +/- 11.3 and 87.3 +/- 9.8 nmol (min)-1 (mg protein)-1 respectively. 4. These observations suggest that Giardia has the capacity to utilise aspartate and alanine and possibly other amino acids as alternative sources of energy. 5. The extrusion or uptake of alanine by Giardia trophozoites may be dictated by the intracellular redox-status of the protozoan parasite or components in the external mileu.

摘要

十二指肠贾第虫（克隆P1C10）的完整滋养体在简单维持培养基（MM）和复杂胆汁补充培养基（BIS - 33）中分别以10.27±0.76和27.6±2.07 ng·hr⁻¹·10⁻⁶个细胞的速率摄取并将L - [U¹⁴C - ]天冬氨酸代谢为¹⁴CO₂。2. 十二指肠贾第虫（克隆P1C10）的完整滋养体在简单培养基（MM）和复杂培养基（BIS - 33）中也分别以20.6±1.1和91.4±17.5 ng·hr⁻¹·10⁻⁶个细胞的速率摄取并将L - [U¹⁴C - ]丙氨酸代谢为¹⁴CO₂。3. 滋养体超声裂解物含有显著水平的天冬氨酸 - 2 - 氧代戊二酸转氨酶（AST；EC 2.6.1.1）和丙氨酸 - 2 - 氧代戊二酸转氨酶（ALT；EC 2.6.2.2）。（23℃时的）比活性分别为95.1±11.3和87.3±9.8 nmol·(min)⁻¹·(mg蛋白质)⁻¹。4. 这些观察结果表明，贾第虫有能力利用天冬氨酸、丙氨酸以及可能的其他氨基酸作为替代能量来源。5. 贾第虫滋养体对丙氨酸的排出或摄取可能由原生动物寄生虫的细胞内氧化还原状态或外部环境中的成分决定。