Plants closing stomata in the presence of harmful gases is believed to be a stress avoidance mechanism. SO , one of the major airborne pollutants, has long been reported to induce stomatal closure, yet the mechanism remains unknown. Little is known about the stomatal response to airborne pollutants besides O . SLOW ANION CHANNEL-ASSOCIATED 1 (SLAC1) and OPEN STOMATA 1 (OST1) were identified as genes mediating O -induced closure. SLAC1 and OST1 are also known to mediate stomatal closure in response to CO , together with RESPIRATORY BURST OXIDASE HOMOLOGs (RBOHs). The overlaying roles of these genes in response to O and CO suggested that plants share their molecular regulators for airborne stimuli. Here, we investigated and compared stomatal closure event induced by a wide concentration range of SO in Arabidopsis through molecular genetic approaches. O - and CO -insensitive stomata mutants did not show significant differences from the wild type in stomatal sensitivity, guard cell viability, and chlorophyll content revealing that SO -induced closure is not regulated by the same molecular mechanisms as for O and CO . Nonapoptotic cell death is shown as the reason for SO -induced closure, which proposed the closure as a physicochemical process resulted from SO distress, instead of a biological protection mechanism.

Biosensors fabricated with whole-cell bacteria appear to be suitable for detecting bioavailability and toxicity effects of the chemical(s) of concern, but they are usually reported to have drawbacks like long response times (ranging from hours to days), narrow dynamic range and instability during long term storage. Our aim is to fabricate a sensitive whole-cell oxidative stress biosensor which has improved properties that address the mentioned weaknesses. In this paper, we report a novel high-throughput whole-cell biosensor fabricated by immobilizing roGFP2 expressing Escherichia coli cells in a k-carrageenan matrix, for the detection of oxidative stress challenged by metalloid compounds. The E. coli roGFP2 oxidative stress biosensor shows high sensitivity towards arsenite and selenite, with wide linear range and low detection limit (arsenite: 1.0 × 10−3–1.0 × 101 mg·L−1, LOD: 2.0 × 10−4 mg·L−1; selenite: 1.0 × 10−5–1.0 × 102 mg·L−1, LOD: 5.8 × 10−6 mg·L−1), short response times (0–9 min), high stability and reproducibility. This research is expected to provide a new direction in performing high-throughput environmental toxicity screening with living bacterial cells which is capable of measuring the bioavailability and toxicity of environmental stressors in a friction of a second.

Green fluorescent protein (GFP) is suitable as a toxicity sensor due to its ability to work alone without cofactors or substrates. Its reaction with toxicants can be determined with fluorometric approaches. GFP mutant gene (C48S/S147C/Q204C/S65T/Q80R) is used because it has higher sensitivity compared to others GFP variants. A novel sodium dodecyl sulfate (SDS) toxicity detection biosensor was built by immobilizing GFP expressing Escherichia coli in k-Carrageenan matrix. Cytotoxicity effect took place in the toxicity biosensor which leads to the decrease in the fluorescence intensity. The fabricated E. coli GFP toxicity biosensor has a wide dynamic range of 4-100 ppm, with LOD of 1.7 ppm. Besides, it possesses short response time (<1 min), high reproducibility (0.76% RSD) and repeatability (0.72% RSD, 2 > 0.98), and long-term stability (46 days). E. coli GFP toxicity biosensor has been applied to detect toxicity induced by SDS in tap water, river water, and drinking water. High recovery levels of SDS indicated the applicability of E. coli GFP toxicity biosensor in real water samples toxicity evaluation.

The cord blood glucose-6-phosphate dehydrogenase (G6PD) enzyme activity of 262 normal term Malaysian neonates (92 Malays, 96 Chinese and 74 Indians) was quantitatively determined by the World Health Organisation method. Analysis of variance for the levels of G6PD enzyme activity by ethnic origin and sex showed that there was a significant difference between mean levels of enzyme activity in the three ethnic groups (P = 0.03) but no difference between the sexes (P = 0.36). Multiple range analysis showed that Malays had significantly higher mean levels of G6PD enzyme activity than those of Chinese (P = 0.01). There was no significant difference between the mean levels of G6PD enzyme activity of Chinese and Indians (P = 0.52), nor was there any difference between those of Malays and Indians (P = 0.08). The difference in levels of G6PD enzyme activity among the different ethnic groups could be due to the existence of different G6PD variants.

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