Hemocyanin lipid uptake in Polybetes pythagoricus is altered by fenitrothion

MONICA CUNNINGHAM; FERNANDO GARCIA; HORACIO GARDA; RICARDO POLLERO

PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY

Elsevier

Año: 2006 vol. 86 p. 57 - 62

0048-3575

The spider very high density lipoprotein (VHDL), which contains hemocyanin as the major apoprotein, transports most of the circulating lipids. In this work, the effect of the pesticide fenitrothion (FS) on the ability of VHDL-apoproteins to uptake different lipids was investigated. For this, VHDL was completely delipidated using Triton X-100 and recombined with different radiolabeled lipids in the presence or the absence of FS. The oligomeric structural integrity was maintained after delipidation as shown by non-denaturating PAGE. In the presence of the insecticide, palmitic acid uptake decreased by 28.2% and 62.4% after treating the apolipoprotein with 10 ppm and 20 ppm FS, respectively. Decreases in the uptake of cholesterol, triolein and phosphatidylcholine caused by FS were 29%, 23% and 31% using 10 ppm, and 40%, 44% and 29% using 20 ppm FS, respectively. Fluorescence measurements with the hydrophobic probes diphenylhexatriene (DPH) and diphenylhexatrienyl-propionic acid (DPH-PA) indicate that FS induces a red shift, decreases the intensity and increases the anisotropy of the emission of these probes in the VHDL. These results indicate that insecticide binding to the lipoprotein enhances the environment polarity and restricts the mobility of these probes at their binding site. These changes at the hydrophobic VHDL binding sites could lead to the decreased affinity for lipids and hydrophobic ligands. It is inferred that FS could alter the normal lipid exchange between this lipoprotein and tissues.