Absence of Fhit protein in primary lung tumors and cell lines with FHIT gene abnormalities.

Genomic alterations and abnormal expression of the FHIT gene at 3p14.2 have been observed in cell lines and primary tumors of the lung. To correlate FHIT locus DNA and RNA lesions with effects on Fhit protein expression, we have analyzed 11 lung cancer cell lines, 15 small cell lung carcinomas, and 38 pairs of non-small cell primary tumors and bronchial mucosa specimens by molecular genetic and immunocytochemical methods. Using specific antibodies against the Fhit protein, we observed concordance between RNA abnormalities and lack of Fhit protein expression in lung tumors and cell lines. In addition, absence of Fhit protein in some precancerous dysplastic lesions suggested that FHIT inactivation may occur at an early phase of lung carcinogenesis

Contrasting responses in leaf nutrient-use strategies of two dominant grass species along a 30-yr temperate steppe grazing exclusion chronosequence

Grazing exclusion practices can be promising restoration techniques where ecosystem degradation follows from rapidly increasing grazing pressure, as widely observed in northern Chinese grasslands. However, the mechanisms of plant-soil interactions responsible for nutrient cycling restoration remain unclear. We examined the functional response of the two most dominant grass species with contrasting nutrient economies to a grazing exclusion chronosequence varying greatly in soil moisture and extractable N and P. The relative biomass of the nutrient acquisitive species Leymus chinensis increased while that of the nutrient conservative Stipa grandis decreased across the chronosequence. Leymus chinensis displayed increasing leaf nutrient concentration and decreasing nutrient resorption with time since grazing exclusion for both N and P. In contrast, S. grandis showed decreasing leaf N and P concentrations and largely stable nutrient resorption. These differences in plasticity, with respect to nutrient stoichiometry and resorption, suggest contrasting abilities of these two dominant species to compete for soil resources and/or differences in their affinity to the changing forms of soil available N and P likely occurring along the restoration gradient. Ecosystem trajectory of change after grazing exclusion appears therefore largely dependent on the nutrient use strategies of co-occurring dominant grassland species