Biochemical and Molecular Bases of Lipid Metabolism in Hydra vulgaris

Here we have studied some biochemical and molecular characteristics of lipid metabolism in the Hydra cnidarian polyp. We have characterized variations in lipid metabolism in response to diet by establishing lipid profiles in starved and fed Hydra, and quantifying with the Red Nile technique the accumulation of lipid droplets in the digestive cells upon starvation. As expected, Hydra uses lipid reserves as fuel for survival, suggesting that fatty acids and cholesterol in the diet are esterified and stored when abundant and then released when fasting. During regeneration, specific classes of lipids appear to be needed, possibly for cell membrane synthesis and/or specific signalling. We finally identified five orthologs of the bilaterian genes encoding the dihydrolipoamide branched-chain transacylase (DBT), hydroxyacyl-CoA dehydrogenase (HCD), choline phosphotransefrase (CHPT), phosphatidylcholine Sterol-O acyltransferase (PCSAT) and lipophorin receptor /LDL (LpR/LDL). Phylogenetic analyses confirm that these enzymes and receptor essential for lipid metabolism are conserved in eumtazoans

Innate immune signaling and the contribution of different regions of capsid to HIV-1 restriction by TRIM5

The cellular factor TRIM5α performs a dual role in the innate immunity. First, TRIM5α has an intrinsic ability to induce the AP-1 and NFκB pathways and contributes to the establishment of the LPS-mediated antiviral state. Second, it functions as a restriction factor, blocking early stages of retroviral infection in a capsid-dependent manner. The connections between these two functions of TRIM5α are debated. We investigated the conservation, in TRIM5 orthologues, of the ability to activate the innate immune pathways and analyzed the signification of this function in the context of TRIM5- mediated HIV-1 restriction. We took the advantage that there are seven TRIM5 orthologues in the mouse, with variable abilities to activate the innate immune signaling, to determine the contribution of this signal activator function to the restriction process. [...