PSBA

There are few reports on block-copolymeric TPE (namely, polyurethane, EVA, SBS, poly (styrene-fo-butyl acrylate) (PSBA))-clay nanocomposites also [196-199]. Choi et al. [196] studied the effect of the silicate layers in the nanocomposites on the order-disorder transition temperature of... 

Mate Z, Sass L, Szekeres M, Vass I, Nagy F (1998) UV-B induced differential transcription of psbA genes encoding the D1 protein of photosystem II in the cyanobacterium Synechocystis 6803. J Biol Chem 273 17439-17444... 

Morden, C.W. and S.S. Golden (1989). psbA genes indicate common ancestry of prochlorophytes and chloroplasts. Nature, 337 382-385. 

Wildner, G.F., U. Heisterkamp, and A. Trebst (1990). Herbicide cross-resistance and mutations of the psbA gene in Chlamydomonas reinhardtii. Z. Naturforschg. Sect. CBiosci., 45 1142-1150. 

In practical terms, the Ser264 to Gly mutation causing triazine resistance reduces plant productivity and yield. This has two agronomic implications first, triazine-resistant weeds carrying this mutation are less competitive (often referred in the literature as reduced fitness) on a per plant basis as compared to their susceptible counterparts, and second, triazine-resistant rapeseed cultivars with Hie mutant psbA gene are less productive than near isogenic, susceptible cultivars (Forcella, 1987 Beversdorf et al, 1988 Hart and Stemler, 1990 Hall et al, 1996). 

Goloubinoff, P., M. Edelman, and R.B. Hallick (1984). Chloroplast-encoded atrazine resistance in Solanum nigrum psbA loci from susceptible and resistant biotypes are isogenic except for a single codon change. Nucleic Acid Res. 12 9489-9496. 

Comparison of deduced amino acid sequences from psbA genes. Note the conservation of the PEST-1ike region contiguous with the a-helix-destabilizing, primary cleavage domain in the 32kDa protein. The arrow indicates the probable site where the precursor piece on the carboxy-terminus is cleaved (22). psbA sequences were compiled as follows (1) Anacystis nidulans copy I, and (2) copy II/III (41). 

Solanum nigrum is the reference sequence (54) and is identical to the Spinacia oleracea, Nicotiana debneyi (8) and Nicotiana tabacurn (55) psbA sequences. (Adapted from ref. 56). 

Of the 869 families derived from plants collected in five populations (Table II), 33 showed at least one seedling with an intermediary fluorescence curve (Figure 1 (21)). These seedlings proved later to have the mutated psbA gene at Position 264 (19) and were moderately resistant to atrazine. They were called Type I (for intermediate level of resistance). The 33 mother plants and their corresponding seed families were called Sp. because they were special susceptible plants that produced mutant plants. 

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