How to easily detect plant NADH-glutamate dehydrogenase (GDH) activity? A simple and reliable in planta procedure suitable for tissues, extracts and heterologous microbial systems.

Plant NADH glutamate dehydrogenase (GDH) is an intriguing enzyme, since it is involved in different metabolic processes owing to its reversible (anabolic/catabolic) activity and due to the oligomeric nature of the enzyme, that gives rise to several isoforms. The complexity of GDH isoenzymes pattern and the variability of the spatial and temporal localization of the different isoforms have limited our comprehension of the physiological role of GDH in plants. Genetics, immunological, and biochemical approaches have been used until now in order to shed light on the regulatory mechanism that control GDH expression in different plant systems and environmental conditions. We describe here the validation of a simple in planta GDH activity staining procedure, providing evidence that it might be used, with different purposes, to determine GDH expression in plant organs, tissues, extracts and also heterologous systems.

Comet assay application in environmental monitoring: DNA damage in human leukocytes and plant cells in comparison with bacterial and yeast tests.

Urban airborne particulate is a complex mixture of air pollutants, many of which have not been identified. However, short-term mutagenesis tests together with chemicophysical parameter analysis are able to better assess air quality and genotoxic load. The findings of continuous monitoring (January 1991-August 1998) of urban air genotoxicity of a Po Valley town (Italy) on Salmonella typhimurium and Saccharomyces cerevisiae are reported. During this period, various measures (catalytic devices, unleaded fuels, annual vehicle overhaul, etc.) to improve air-dispersed pollutant control were enforced. However, a continuous presence of genotoxic compounds is shown and more qualitative than quantitative changes are evident. We also demonstrate the ability of the Comet assay to detect DNA-damaging agents in airborne particulate samples. We applied the test to human leukocytes and, with major improvements, to plant cells (Allium cepa roots and epigean tissues of Impatiens balsamina). The first findings on human leukocytes confirm the sensitivity of this assay, its peculiarity and its applicability in assessing genotoxicity in environmental samples. The capability of plants to show the response of multicellular organisms to environmental pollutants largely counterbalances a probable lowering in sensitivity. Moreover, application of the Comet test to epigean tissues could be useful in estimating the bioavailability of and genotoxic damage by air pollutants, including volatile compounds (ozone, benzene, nitrogen oxides, etc.) to higher plants.