INIBIBB   05455
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BAHIA BLANCA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Nicotinic Receptors from C. elegans
Autor/es:
HERNANDO GUILLERMINA
Lugar:
Mendoza, Argentina
Reunión:
Workshop; Caenorhabditis elegans a powerful Model for Biological Research; 2009
Institución organizadora:
Universidad Nacional de Cuyo-PROBIOL
Resumen:
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The free-living
nematode C. elegans, is a representative member of a large phylum
that includes many parasitic members. Nematode nicotinic acetylcholine
receptors (nAChRs) are pentameric ligand-gated ion channels that mediate
synaptic transmission throughout the nervous system. The muscle
levamisole-sensitive nAChR (L-AChR) is the target of anthelmintic drugs, such
as levamisole, which act as potent agonists. Although several subunits have
been reported to form the L-AChR, its subunit composition and the role of each
subunit remain unknown. LEV-8 is a a-type subunit of the L-AChR that when
mutated confers partial resistance to the levamisole paralytic effects. To
explore the functional role of LEV-8, we performed cell-attached and whole-cell
recordings of embryonic muscle cells from wild-type and mutant strains.
Recordings from the null mutant strain lev-8(x-15) show ACh- and
levamisole-activated channels with a conductance of 39.6±4pS. The kinetics of
the channels differs from that of wild-type strains. The mean open times for
ACh- and levamisole-activated channels are 3.9- and 1.5-fold more prolonged,
respectively, than those from wild-type strains. The frequency of channel
openings is markedly reduced with respect to that of wild-type strains.
Moreover, in the LEV-8 null mutant strain the frequency decreases significantly
with the time of recording, suggesting enhanced desensitization. Macroscopic
currents reveal 1.5-fold increase of the desensitization rate and decreased
recovery rate from desensitized states in the LEV-8 null mutant strain when
compared to the wild type.