摘要
Objective:To isolate and demonstrate the mechanism of metal transport in cobalt-sensitive mutant(CSM)of Neurospora crassa(N.crassa).Methods:Isolation of CSM of N.crassa,I_(50)determination,growth measurements,metal ion uptake studies and sexual crosses were performed to determine the mechanism of sensitivity and locus.Results:CSMs of N.crassa were isolated by mutagenesis with diethyl sulfate.More than 500 isolates were screened and out of these isolates,CSM-I was 5-fold and CSM-II was 10-fold sensitive to Co on liquid medium as compared to the wild type.Compositional analysis of cell wall revealed the decrease in total phosphate content.N.crassa CSM bound much less cobalt to cell wall fraction than wild type.The data indicated closer linkage between resistance and mating type locus(mat),which is,located on LG I.Conclusions:A CSM of N.crassa is 5-fold more sensitive than wild type and cross sensitive to nickel and copper and hyper-accumulates 2-4 fold more toxic metal ions over wild type.The mechanism for sensitivity is decreased in cobalt-binding to cell wall fraction and increased intracellular uptake.N.crassa-acon-3 morphologically resembles the CSM,cobalt-sensitive and maps to similar locus.
