University of Alabama

About: University of Alabama is a education organization based out in Tuscaloosa, Alabama, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 27323 authors who have published 48609 publications receiving 1565337 citations. The organization is also known as: Alabama & Bama.

Reciprocal regulation of TGF-β and reactive oxygen species: A perverse cycle for fibrosis

Abstract: Transforming growth factor beta (TGF-β) is the most potent pro-fibrogenic cytokine and its expression is increased in almost all of fibrotic diseases. Although signaling through Smad pathway is believed to play a central role in TGF-β's fibrogenesis, emerging evidence indicates that reactive oxygen species (ROS) modulate TGF-β's signaling through different pathways including Smad pathway. TGF-β1 increases ROS production and suppresses antioxidant enzymes, leading to a redox imbalance. ROS, in turn, induce/activate TGF-β1 and mediate many of TGF-β's fibrogenic effects, forming a vicious cycle (see graphic flow chart on the right). Here, we review the current knowledge on the feed-forward mechanisms between TGF-β1 and ROS in the development of fibrosis. Therapeutics targeting TGF-β-induced and ROS-dependent cellular signaling represents a novel approach in the treatment of fibrotic disorders.

Regulation of Leaf Breakdown by Fungi in Streams: Influences of Water Chemistry

Abstract: We examined the influence of stream water chemistry on relationships between fungal activity and breakdown rates of yellow poplar (Liriodendron tulipifera) leaves in eight streams that varied with respect to pH and nutrient (nitrate and phosphate) con- centrations. We also performed a reciprocal exchange experiment of leaves that had been colonized by microorganisms in two streams with contrasting water chemistries. Decom- poser activity varied greatly depending on the stream in which the leaves were placed. Variation in breakdown rates of yellow poplar leaves was over 9-fold maximum ATP concentrations associated with leaves varied as much as 8-fold, and maximum sporulation rates of fungi associated with leaves varied over 80-fold among streams. Among all streams, nitrate, phosphate, and temperature were positively correlated with one another and with decomposer biomass and activity. When hardwater streams were analyzed separately, nitrate concentration was the only variable that was significantly correlated with all measures of microbial activity and leaf breakdown. Consequently, nitrate concentration appeared to explain much of the variation we detected among streams. Responses to the reciprocal exchange experiment were rapid, with significant changes occurring within the first 5 d after the transfer. Leaves transferred from the hardwater stream containing relatively high concentrations of nitrate and phosphate to the softwater stream containing low concentra- tions of nutrients exhibited by large decreases in both ATP concentrations and sporulation rates, whereas ATP concentrations and sporulation rates increased when leaves received the reciprocal transfer. The fungi associated with decomposing leaves in streams appear to obtain a significant portion of their nutrients (e.g., nitrogen and phosphorus) from the water passing over the leaf surface. These results indicate that the chemistry of the water can be an important regulator of leaf breakdown in streams by affecting the activity of decomposer fungi.