Microbial response to crude oil and Corexit 9527: SEAFLUXES enclosure study

The response of marine bacteria to Corexit 9527, with and without Prudhoe Bay crude oil labeled withn–(1–¹⁴C)hexadecane, in a temperate pelagic environment was monitored over 22 days using controlled ecosystem enclosures. The results indicated that Corexit and Corexit-dispersed crude oil stimulated bacterial production by serving as substrates and/or by inducing the release of organic compounds from the indigenous phytoplankton population. Highest bacterial standing stock was observed in the enclosure treated with a mixture of Corexit and crude oil, in which a large fraction of the predominant bacterivores were eliminated. Biodegradation appeared to be more significant than abiotic processes in contributing to the loss of low volatility n-alkanes in Corexit-dispersed oil. Twenty-two days following its addition, 50% of the radiotracer was recovered: 3% in the suspended particulate fraction, 10% in sedimentary material, 36% as CO₂, and less than 1% in the dissolved organic pool.     

RhoA biological activity is dependent on prenylation but independent of specific isoprenoid modification.

Recent studies showed that specific isoprenoid modification may be critical for RhoB subcellular location and function. Therefore, we determined whether the function of the highly related RhoA protein is also critically dependent on specific isoprenoid modification: (a) in contrast to observations with RhoB or Ras proteins, where farnesylated and geranylgeranylated versions showed differences in subcellular location, both prenylated versions of RhoA showed the same plasma membrane and cytosolic location; (b) a farnesylated version of activated RhoA(63L) retained the same diverse functions as the normally geranylgeranylated RhoA(63L) protein, and both proteins show indistinguishable abilities to stimulate gene expression, cause growth transformation of NIH 3T3 mouse fibroblasts, to stimulate the motility of T47D human breast epithelial cells, and to block HIV-1 viral replication and gene expression; and (c) cells expressing farnesylated RhoA retained sensitivity to the growth inhibition caused by inhibition of geranylgeranyltransferase I, indicating that other proteins are critical targets for inhibitors of geranylgeranylation.