A new short-term toxicity assay using Aspergillus awamori with recombinant aequorin gene

Abstract

Background: Most currently available short-term toxicity assays are based on bacterial cells. Therefore there is a need for novel eukaryotic microbial bioassays that will be relevant to higher eukaryotes such as animals and plants. Ca 2+ is a universal intracellular signalling molecule found in all organisms from prokaryotes to highly specialized animal cells. In fungi calcium has been demonstrated to be involved in control of many important processes. The recombinant aequorin gene from the jellyfish Aequorea victoria responsible for the expression of the Ca 2+ -sensitive aequorin photoprotein has been cloned in the filamentous fungus Aspergillus awamori. This has allowed real life monitoring of [Ca 2+ ] c changes in living fungal cells. When subjected to different physico-chemical stimuli fungal cells respond by transiently changing the concentration of free Ca 2+ in the cytosol ([Ca 2+ ] c ) and the pattern of these changes (Ca 2+ signature) is specific to each particular stimulus. Therefore it was interesting to investigate whether different environmental toxicants would be able to affect the pattern of [Ca 2+ ] c changes in a reproducible and dose dependant manner.

Intracellular free Ca2+signals antibiotic exposure in cyanobacteria

“…They concluded that cells prepared to face high and rapid Ca 2+ cytosolic waves were tter for survival. Kozlova et al 26 also tried to correlate Ca 2+ signatures triggered by Cr 6+ , Zn 2+ and 3,5-dichlorophenol in apoaequorin-expressing fungus Aspergillus awamori with toxicity; for this, they chose length of the Ca 2+ transients (LT 50 ) to compare with the EC 50 at 5 and 30 min of the Aliivibrio scheri classical bioluminescent toxicity assay. All toxicants provoked a response in one or more of the studied parameters, but LT 50 was not the best parameter to compare with the A.…”

“…7,[15][16][17][18] There are numerous studies reporting that a wide range of pollutants affect Ca 2+ homeostasis/signalling in a number of organisms [19][20][21][22][23] with microorganisms being under represented. [24][25][26][27][28][29][30] Regarding specically antibiotics, there are few studies reporting that antibiotics (mostly aminoglycosides and tetracycline) signicantly alter Ca 2+ homeostasis in animal and human cell lines. [31][32][33][34][35] Our group using the apoaequorin expressing cyanobacterial Anabaena strain, Anabaena sp.…”

Gold–Carbon Nanocomposites for Environmental Contaminant Sensing

“…The widespread production and use of synthetic and natural chemicals by society have led to the release of huge amounts of toxic materials into the environment. Thus, their persistence has necessitated the development of fast and cost-effective toxicity tests to protect humans and other organisms [ 182 ]. Toxicity assays are necessary for the avoidance of environmental destruction and obstacles to the health of the human body.…”