| Autor: |
Prasad, Anil, Kaur, Sukhbir, Malla, Nancy, Ganguly, N.K., Mahajan, R.C. |
| Zdroj: |
Molecular & Cellular Biochemistry; Aug2001, Vol. 224 Issue 1/2, p39-44, 6p |
| Abstrakt: |
The present study is an attempt to look into the role of Ca2+ in signaling the transformation of promastigotes to axenic amastigotes. An estimation of intracellular free calcium concentration at 6 h intervals during the conversion of promastigotes to axenic amastigotes (72 h) revealed a 10 fold increase in [Ca2+]i at the initial 6–12 h during the conversion. This was followed by declining levels till 60 h and the concentration thereafter remained constant. Axenic amastigotes (72 h) had a 5 fold higher [Ca2+]i as compared to the promastigotes. A 30–40% decrease in [Ca2+]i after pretreatment of cells with dentrolene and a gradual rise of intracellular Ca2+ in [Ca2+] free medium indicates the role of intracellular calcium pools in the elevation of [Ca2+]i. A sudden increase in [Ca2+]i on addition of NH4Cl (20 mM) in the cells grown in Ca2+ free medium indicates the presence of acidocalcisomes, as intracellular Ca2+ storing pool, in L. donovani. To study the role of Ca2+ influx from the external medium in the morphogenetic transformation and in the elevation of [Ca2+]i a 45Ca2+ uptake study was performed. Maximum uptake of 45Ca2+ was observed in the initial 24 h of transformation and maximum Ca2+ ATPase activity was also observed between 24–42 h. So the presence of low Ca2+ in the cytosol, existence of intracellular Ca2+ pools and presence of mechanisms to maintain the Ca2+ homeostasis in the cells suggests that Ca2+ can be an appropriate candidate for a second messenger during the morphogenetic transformation of L. donovani. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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