Direct interaction between Tks proteins and the N-terminal proline-rich region (PRR) of NoxA1 mediates Nox1-dependent ROS generation

NADPH oxidase (Nox) family enzymes are one of the main sources of cellular reactive oxygen species (ROS), which have been implicated in several physiological and pathophysiological processes. To date seven members of this family have been reported, including Nox1-5 and Duox1 and 2. With the exception of Nox2, the regulation of the Nox enzymes is still poorly understood. Nox1 is highly expressed in the colon, and requires two cytosolic regulators, the organizer subunit NoxO1 and the activator subunit NoxA1, as well as the binding of Rac1 GTPase, for its activity. Recently, we identified the c-Src substrate proteins Tks4 and Tks5 as functional members of a p47^phox-related organizer superfamily. As a functional consequence of this interaction, Nox1 localizes to invadopodia, actin-rich membrane protrusions of cancer cells which facilitate pericellular proteolysis and invasive behavior.Here, we report that Tks4 and Tks5 directly bind to NoxA1. Moreover, the integrity of the N-terminal PRR of NoxA1 is essential for this direct interaction with the Tks proteins. When the PRR in NoxA1 is disrupted, Tks proteins cannot bind NoxA1 and lose their ability to support Nox1-dependent ROS generation. Consistent with this, Tks4 and Tks5 are unable to act as organizers for Nox2 because of their inability to interact with p67^phox, which lacks the N-terminal PRR, thus conferring a unique specificity to Tks4 and 5.Taken together, these results clarify the molecular basis for the interaction between NoxA1 and the Tks proteins and may provide new insights into the pharmacological design of a more effective anti-metastatic strategy.     

Loss of Nitrogen,Phosphorus, and Potassium Through Crop Harvests in Agroecosystems of Qianjiang,Hubei Province,PR China

The level of chemical fertilization in China is considerably higher than that normally applied in Western countries. For example, in the last decade the use of N-P-K chemical fertilizers increased, within the province of our study, from about 300 kg/ha in 1980 to about 850 kg/ha in 1990. Data on total amounts on nitrogen, phosphorus, and potassium that are removed with the harvest are necessary in determining and optimizing the amount of chemical fertilizers to be applied to different crops and in different cropping patterns. In this article we report the results of analyses of N, P, and K content of soils and different parts of different plants (soybean, cotton, rice, peanut, radish, Chinese cabbage, sesame, pepper, eggplant, and ambary) typically grown in rural areas of Southern China and provide an estimate of the balance of these nutrients under the five cropping systems that are dominant in the studied area.     

Identification, Pathogenicity and Comparative Virulence of Fusarium spp. Associated with Diseased Euphorbia spp. in Europe

Fusarium spp. isolated from diseased Euphorbia spp. in Europe were assessed for pathogenicity to North American accessions of leafy spurge ( Euphorbia esula/virgata ). Of the nine strains of Fusarium spp. isolated from diseased E. stepposa or E. virgata in the Caucasus region of Russia and E. esula/virgata in southern France, all were pathogenic to leafy spurge. There were significant differences in virulence among strains. Four strains, including the two that were most virulent, were identified as F. oxysporum . Four of the five other strains were identified as F. solani and one was identified as F. proliferatum . Three of the four most virulent strains to leafy spurge were isolated from E. stepposa . The most virulent strain was associated with root damage caused by insect biological control agents, as found earlier with domestic strains of Fusarium spp. pathogenic to leafy spurge. Two strains identified as F. solani were vegetatively compatible. It was concluded that further screening of a larger set of strains of foreign Fusarium spp. under quarantine conditions in the US or in limited overseas facilities would be justified, and could yield promising biological control agents for leafy spurge.