No abstract

New D-π-A-π-D type dyes based on compounds of the pyrimidine family, bearing thiophene linkers, have been designed, synthesized and characterized. The fluorescence behavior of these fluorophores have been evaluated for fifteen nitro compounds. The detection limits for these fluorophores in relation to nitro explosives in acetonitrile solution proved to be in the range from 10 -1 to 10 -6 mol/L. The sensor prototypes for handheld sniffer «Nitroscan» (Plant «Promautomatika», Ekaterinburg, Russia), based on these fluorophores, have been fabricated and used, as illustrated by reversible and sensitive fast detection of nitrobenzene in vapor phase concentrations up to 0.06 ppm.

Developing seeds of some higher plants are photosynthetically active and contain chlorophylls (Chl), which are typically destroyed at the late stages of seed maturation. However, in some crop plant cultivars, degradation of embryonic Chl remains incomplete, and mature seeds preserve green colour, as it is known for green-seeded cultivars of pea (Pisum sativum L.). The residual Chl compromise seed quality and represent a severe challenge for farmers. Hence, comprehensive understanding of the molecular mechanisms, underlying incomplete Chl degradation is required for maintaining sustainable agriculture. Therefore, here we address dynamics of plastid conversion and photochemical activity alterations, accompanying degradation of Chl in embryos of yellow- and green-seeded cultivars Frisson and Rondo respectively. The yellow-seeded cultivar demonstrated higher rate of Chl degradation at later maturation stage, accompanied with termination of photochemical activity, seed dehydration and conversion of green plastids into amyloplasts. In agreement with this, expression of genes encoding enzymes of Chl degradation was lower in the green seeded cultivar, with the major differences in the levels of Chl b reductase (NYC1) and pheophytinase (PPH) transcripts. Thus, the difference between yellow and green seeds can be attributed to incomplete Chl degradation in the latter at the end of maturation period.