UV inactivation

Perhaps the best-characterized lesion in DNA associated with uv inactivation and mutagenesis is that involving the intrastrand photodimerization of adjacent thymine residues this lesion is almost wholly repaired by photodissociation of the dimers at shorter wavelengths in the photoreactivation process. Production of the chh dimer in this case, promoted by the configuration of adjacent molecules on the same sugar-phosphate strand, must however involve a rotational displacement of 36°, following the reduction of 0.6 A in molecular separation. 

Figure 1 Procedure of gene transfer by Sendai virus (HVJ)-liposomes. DNA and nuclear proteins are incorporated into liposomes by vortex-ultrasonication-annealing method, and the liposomes are fused with UV-inactivated Sendai virus. The resulting fusigenic viral liposomes can fuse with cell membrane to introduce DNA and nuclear protein complex directly into the cytoplasm. Nuclear protein such as HMG-1 can enhance the expression of foreign DNA in the nucleus.

Another and more convincing explanation for this discrepancy of previous and recent studies related to the inactivation of Cryptosporidium refers to the methods of viability testing. So, it seems that in vitro viability assays (chemical excystation and vital stains) that have been used previously may have significantly underestimated the inactivation efficacy of UV-C irradiation of the parasites compared with in vivo infectivity assays applied in recent studies using neonatal mouse models (Craik et al, 2001). This was also demonstrated by UV inactivation of Giardia muris cysts using MP Hg lamps (Craik et al., 2000). 

The selective UV-inactivation method is effective for the deposition of a single enzyme-immobilized membrame on a FET, but it is not possible to deposit several different enzyme-immobilized membranes on one FET chip. Other photolithographic methods, outlined in Fig. 8, do not have this disadvantage. The methods are applicable to the simultaneous deposition of different membranes on a FET chip. In other words, these methods are usable for the preparation of a multifunctional enzymatically coupled FET. 

MS 2 is commonly chosen for UV inactivation studies for the following reasons... 

Rate constant for fast decay population, cm / j,W s Rate constant for slow decay population, cm /mW s UV inactivation rate coefficient, cm /mW s Disinfection rate constant, s ... 

G-A. Shin, K. G. Linden, M. J. Arrowood, and M. D. Sobsey, Low-pressure UV inactivation and DNA repair potential of Cryptosporidium parvum oocysts. Applied Environmental Microbiology 67(7), 3029-3032 (2001). 

The subject of UV inactivation cannot be left without considering the possibility of interactions with other abiotic factors attributing to variations in persistence. Using simulated sunlight, the interaction of UVA and UVB (290-400 nm) was observed [55] with pH (at 3, 6 and 9), water, and temperature (at 10, 22, 35 and 50°C) on the inactivation of HzSNPV. No interactions were observed with either temperature or pH however HzSNPV was more sensitive when exposed to water than dry vims. McLeod... 

FIGURE 3. Degradation of the D—1 polypeptide after UV inactivation of spinach thylakoids and protection by inhibitors... 

HELENTJARIS, T. and EHRENFELI), E. Inhibition of host cell protein synthesis by UV-inactivated poliovirus. J. Virol. (I977)f... 

Cell fusion was mediated by UV inactivated Sendai virus supplied by Dr. Y. Okada (Osaka Univ.). 

Among the species of propionibacteria tested, i.e., P. rubrum, P. raffinosaceum, P. acidipropionici, P. shermanii, P. coccoides, P. acnes the highest effect was found in P. shermanii and P. acidipropionici, while P. coccoides and P. acnes did not exert any protective effects in UV-inactivated E. coli cells (Vorobjeva et al., 1996b). The protective substances in the extract are dialyzable and have molecular weights higher than 12 kDa. 

By ion-exchange chromatography on DEAE-Sepharose FF, the two ammonium sulfate fractions (primary fractions) were separated into subfractions (Fig. 2.8). Seven subfractions showed protective activity in E. coli inactivated by UV light. When the subffactions were analyzed by SDS polyacrylamide gel electrophoresis and HPLC, it was found that the subfraction AF2-2.5 contained mostly a single protein, whereas the other subfractions were composed of mixtures of proteins and peptides of different molecular weights. The molecular weight of subfraction AF2-2.5 was determined at 44 2 kDa (Zinchenko et al, 1998). The protective activity of subfraction AF2-2.5 in UV-inactivated E. coli was dependent on its concentration in the range of 10-60 pg of protein per ml. 

Foschino R, Galli A, Ponticelli G and Volonterio G (1988) Propionic bacteria activity at different culture conditions. Ann Microbiol 38 207-222 Fraikin GY, Vorobjeva LI, Khodjaev EY, Pinyaskina EV and Ponomareva GM (1995) Protective and reactivating effects of cell extract of a propionic acid bacterium on UV-inactivated Candida guilliermondii and Escherichia coli. Microbiology 64 640-644 Francalanci F, Davis NK, Fuller JQ, Murfitt D and Leadlay PF (1986) The subunit structure of methylmalonyl-CoA mutase from Propionibacterium shermanii. Biochem J 236 489-494... 

Vorobjeva LI, Khodzhaev EY and Ponomareva GM (1995c) Mechanism of reactivation of the UV-inactivated cells of Escherichia coli by cell extracts of propionic acid bacteria. Microbiology 64 555-559... 

UV Inactivation. Most NPVs lose 50% or more of their original activity in one or two days when sprayed on plants in the field. This inactivation is associated with exposure to sunlight and more specifically, the UV portion of sunlight (28). This has led to a search for materials that could be added to viral formulations to protect them from UV inactivation. 

Hanafusa, H., 1960, Killing of L cells by heat- and UV-inactivated vaccinia virus. Bike ns J. 3 191. 

Negreanu, Y., Reinhertz, Z., and Kohn, A., 1974, Effects of adsorption of UV-inactivated parainfluenza (Sendai) virus on the incorporation of amino acids in animal host cells, J. Gen. Virol. 22 265. 

Shaw, J. E., and Cox, D. C., 1973, Early inhibition of cellular DNA synthesis by high multiplicities of infectious and UV-inactivated reovirus, J. Virol. 12 704. 

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