THESIS
2022
1 online resource (xxi, 162 pages) : illustrations (some color)
Abstract
The biosensor is gradually becoming a potential sensor to monitor the environmental
pollution, especially their effects on organisms. The autofluorescence intensity (FITC channel)
of an adenine deficient yeast (Ade(-) yeast) was enhanced in the presence of Zn. The biosensor
could accurately quantify the extracellular concentrations of labile Zn ranging from 0.01 to 0.5
μM in complex medium. As Ade(-) yeast responds to intracellular Zn, we employed it as a
model eukaryote to quantify the Zn influx, transportation between labile and storage pools, and
efflux under different Zn exposure levels ( 1 μM). Yeast regulated Zn uptake from the
extracellular source by controlling the Zn influx at the bio-interface. Under exposure of such
low dose of Zn, transportation between labile Zn and storage...[
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The biosensor is gradually becoming a potential sensor to monitor the environmental
pollution, especially their effects on organisms. The autofluorescence intensity (FITC channel)
of an adenine deficient yeast (Ade(-) yeast) was enhanced in the presence of Zn. The biosensor
could accurately quantify the extracellular concentrations of labile Zn ranging from 0.01 to 0.5
μM in complex medium. As Ade(-) yeast responds to intracellular Zn, we employed it as a
model eukaryote to quantify the Zn influx, transportation between labile and storage pools, and
efflux under different Zn exposure levels (< 1 μM). Yeast regulated Zn uptake from the
extracellular source by controlling the Zn influx at the bio-interface. Under exposure of such
low dose of Zn, transportation between labile Zn and storage Zn pools or Zn efflux to the
extracellular environment was not obvious. As dissolved Ag decreased the Zn directed
fluorescence increase of Ade(-) yeast, we used Ade(-) yeast loaded with Zn to quantify the
concentration of extracellular ultra-small AgNPs. The lowest detectable concentration of
AgNPs (7 nm) was 8.9 μg/L, while the bio-response induced by larger AgNPs (20 nm) did not
change with increasing AgNPs concentration. Ade(-) yeast selectively collected the ambient
ultra-small AgNPs and acted as a screener to differentiate small AgNPs and large ones. Despite
the newborn bud could act as an outlet to spit out the invasive AgNPs, the depuration of total
Ag from yeast could be inhibited by the continuously growing daughter bud. The secreted
complex was defined as exosome escaped by vesicle related exocytosis and composed of
organic corona. Numerous AgNPs were evenly distributed in the complex and shrinks to as
small as half of the originally synthesized AgNPs after cellular transformation. Based on the
specific response of model yeast to intracellular labile Zn, contents of Zn(II) and AgNPs in the
environment are quantified and the intracellular behavior of both Zn(II) and AgNPs can be
simultaneously revealed.
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