Authors (see attached article) state that “household air is more polluted than office air and school air, and those who spend much of their time at home, such as children and homeworkers, receive a proportionately higher dose of ‘home air carcinogens’ than the general public.” Among home air carcinogens, volatile organic carcinogens (VOCs) are most common. VOCs include benzene, formaldehyde, carbon tetrachloride, acetaldehyde, chloroform, and ethylene dichloride –– many of which are found in cleaning agents and byproducts of cooking).
[Whether these chemicals actually reach potentially ‘serious’ or ‘carcinogenic’ danger in households –– is debatable, as has been discussed in these GEITP pages before, i.e. do these chemicals obey the linear no-threshold (LNT) model, or is there a level at which the VOC can be detoxified, before cancer is initiated? We have previously discussed ‘extremely sensitive instrumentation’ vs ‘Avogadro’s number’.]
Biochemists in the cytochrome P450 field are aware of a mammalian enzyme, CYP2E1, which is well known to detoxify many of these VOCs into innocuous byproducts. Although not normally inducible, elevated expression of human liver CYP2E1 was found –– at autopsy of a motorcyclist who had extremely high levels of blood alcohol (ethanol) at the time of death. This clinical finding is consistent with rat/mouse experiments showing that liver CYP2E1 can be induced by ethanol and, in turn, the enzyme metabolizes ethanol.
Authors therefore devised a plan to insert CYP2E1 (from rabbit liver) into a houseplant (Epipremnum aureum; common name pothos ivy). The binary vector used by these authors (to transform the pathos ivy) includes: T35s (terminator of the CaMV 35S cauliflower mosaic virus gene); hpt (hygromycin phosphotransferase gene for selecting clones because this provides hygromycin resistance); OsActin (promoter of actin gene of Oryza sativa, i.e. rice); Tmas (terminator of mannopine synthase gene from Agrobacterium tumefaciens, a bacterium that causes crown gall disease); 2e1 (CYP2E1 cDNA from rabbit); ZmUbi (ubiquitin gene promoter of Zea mays, i.e. corn); PvUbi, (ubiquitin promoter of ubiquitin gene of Panicum virgatum, i.e. switchgrass); egfp (jellyfish enhanced green fluorescent protein, used to detect which plant cells express the vector); Trbc (terminator of rubisco small subunit gene, used to help delay RNA-silencing in plants); and LB & RB (left and right borders of the transgene). Each of these DNA segments was cleverly chosen for a specific reason in order to express this mammalian gene in a plant.
As proof-of-principle, authors then demonstrated that CYP2E1 was expressed in the pothos ivy. Authors showed that the resulting genetically modified plant has sufficient detoxifying activity against benzene and chloroform –– suggesting that biofilters (such as the one constructed herein) in transgenic plants might be useful in removing harmful VOCs from home air at substantial rates. 🙂
DwN
Environ Sci Technol DOI: 10.1021/acs.est.8b04811