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Accueil > Publications > Recherche par années > Années 2000 > 2004

2004

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A method to quantify and analyze the foraging activity of honey bees : Relevance to the sublethal effects induced by systemic insecticides

The assessment of agrophannaceuticals’ side effects requires more realistic simulations of field conditions than those deduced from the dose-lethality relation obtained under laboratory conditions. Because the presence of sublethal doses or concentrations may also alter the behavior of foraging insects, we attempted to devise a quantifiable and accurate protocol for evidencing various alterations in free-flying bees. Such a protocol was illustrated by testing new classes of systemic insecticides. The protocol focused on video recording to quantify the foraging activity of small colonies of honey bees confined in insect-proof tunnels. The basis of the protocol was not the colony itself but the change in each colony on a specific day and between days.

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Alpha-Synuclein filaments bind the transcriptional regulator HMGB-1

Abnormal accumulation of a-synuclein filaments in Lewy bodies is a neuropathological hallmark of Parkinson’s disease and sequestration of cellular protein into these protein aggregates may contribute to the degenerative process. We identified the transcriptional co-factor high mobility group protein I (HMGB-1) as a ligand for a-synuclein filaments by a filament spin-down technique, mass spectrometric peptide mapping and immunoblotting. HMGB-1 binds preferentially to aggregated alpha-synuclein and is present in a-synuclein filament-containing Lewy bodies isolated from brain tissue affected with dementia with Lewy bodies or Parkinson’s disease. Our results demonstrate that a-synuclein filaments hold the potential for disturbing the cellular gene expression as they can sequester a component involved in cellular transcription regulation.

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An efficient and facile nitration of phenols with nitric acid/zinc chloride under ultrasonic conditions

An efficient and facile nitration of phenols using nitric acid/zinc chloride under ultrasonic condition has exhibited significant chemo as well as regioselectivity. This study has been extended to other aromatic compounds like naphthalene and anthracene.

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Base pairing at the stem-loop junction in the SL1 kissing complex of HIV-1 RNA : A thermodynamic study probed by molecular dynamics simulation

The thermodynamics of the opening/closure process of a GC base pair located at the stem-loop junction of the SL1 sequence from HIV-1(Lai) genomic RNA was investigated in the context of a loop-loop homodimer (or kissing complex) using molecular dynamics simulation. The free energy, enthalpy and entropy changes for the closing reaction are 0 kcal(.)mol(-1), -11 kcal(.)mol(-1) and -0.037 kcal(.)mol(-1.)K(-1) at 300degrees K respectively. Furthermore it is found that the free energy change is the same for the formation of a I I nucleotide loop closed with UG and for the formation of a 9 nucleotide loop closed with GC. Our study evidences the high flexibility of the nucleotides at the stem-loop junction explaining the weak stability of this structure.

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