Evaluation of Acute Toxicity and Antioxidant Response of Earthworm Exposed to a Lignin-Modified Crosslinked Hydrogel.

Hydrogels are polymers of great importance due to their multiple applications, which have led to an exponential increase in their production. However, once they have fulfilled their function, they become waste and their ecotoxicological effects are unknown. The aim of the present study was to evaluate the acute toxicity and total antioxidant capacity of the earthworm (Eisenia fetida) exposed to a terpolymeric hydrogel (acrylic acid, acrylamide, and 2-acrylamido-2-methyl-1-propane-sulfonic acid) crosslinked with modified kraft lignin. Four different amounts of hydrogel per unit area were evaluated (0.0924, 0.1848, 0.9242, and 1.848 mg hydrogel/cm2) plus a control, and three replicates were performed for each group. Starting from the amount of 0.1848 mg hydrogel/cm2, the earthworms showed physiological and behavioral alterations; at higher amounts, 0.9242 and 1.848 mg hydrogel/cm2, more acute signs were observed with mortality rates of 51.7% and 100%, respectively. On the other hand, the antioxidant activity assay showed that the higher the hydrogel exposure amount, the higher the oxidative stress, as evidenced by lower antioxidant activity (67.09% inhibition of the ABTS●+ radical). Therefore, we concluded that the lignin-modified hydrogel generated oxidative stress and acute lethal toxic effects in Eisenia fetida.

Reduced dNTP binding affinity of 3TC-resistant M184I HIV-1 reverse transcriptase variants responsible for viral infection failure in macrophage.

We characterized HIV-1 reverse transcriptase (RT) variants either with or without the (-)-2',3'-deoxy-3'-thiacytidine-resistant M184I mutation isolated from a single HIV-1 infected patient. First, unlike variants with wild-type M184, M184I RT variants displayed significantly reduced DNA polymerase activity at low dNTP concentrations, which is indicative of reduced dNTP binding affinity. Second, the M184I variant displayed a approximately 10- to 13-fold reduction in dNTP binding affinity, compared with the Met-184 variant. However, the k(pol) values of these two RTs were similar. Third, unlike HIV-1 vectors with wild-type RT, the HIV-1 vector harboring M184I RT failed to transduce cell types containing low dNTP concentrations, such as human macrophage, likely due to the reduced DNA polymerization activity of the M184I RT under low cellular dNTP concentration conditions. Finally, we compared the binary complex structures of wild-type and M184I RTs. The Ile mutation at position 184 with a longer and more rigid beta-branched side chain, which was previously known to alter the RT-template interaction, also appears to deform the shape of the dNTP binding pocket. This can restrict ground state dNTP binding and lead to inefficient DNA synthesis particularly at low dNTP concentrations, ultimately contributing to viral replication failure in macrophage and instability in vivo of the M184I mutation.

High-throughput proteomics for alcohol research.

This report summarizes the proceedings of a satellite symposium of the 2003 Research Society on Alcoholism meeting held on June 21, 2003, in Fort Lauderdale, FL. The goal of this symposium, sponsored by the NIAAA, was to identify new proteomic directions in alcohol research that will (1) enable studies that focus on characterizing protein function, biochemical pathways, and networks to understand alcohol-related illnesses; (2) identify protein-protein interactions, posttranslational modifications, and subcellular localizations; (3) identify molecular targets for medication development; (4) develop biomarkers for susceptibility, dependence, consumption, and relapse, as well as alcohol-induced pathologies; and (5) develop high-throughput drug screens to test the efficacy of therapeutics that control alcohol-induced diseases. The purpose of the symposium was also to promote the application of high-throughput proteomic approaches, including isolation of membrane-bound proteins, in situ proteomics, large-scale two-dimensional separations, protein microarray platforms, mass spectrometry, matrix-assisted laser desorption/ionization, matrix-assisted laser desorption/ionization time-of-flight, liquid chromatography-tandem mass spectrometry, and isotope-coded affinity tags. In addition, the development of protein network maps by using new bioinformatics approaches for database mining was also discussed.