RESUMO
The neuropeptide CAP2b stimulates fluid transport obligatorily via calcium entry, nitric oxide, and cGMP in Drosophila melanogaster Malpighian (renal) tubules. We have shown by RT-PCR that the Drosophila L-type calcium channel alpha1-subunit genes Dmca1D and Dmca1A (nbA) are both expressed in tubules. CAP2b-stimulated fluid transport and cytosolic calcium concentration ([Ca2+]i) increases are inhibited by the L-type calcium channel blockers verapamil and nifedipine. cGMP-stimulated fluid transport is verapamil and nifedipine sensitive. Furthermore, cGMP induces a slow [Ca2+]i increase in tubule principal cells via verapamil- and nifedipine-sensitive calcium entry; RT-PCR shows that tubules express Drosophila cyclic nucleotide-gated channel (cng). Additionally, thapsigargin-induced [Ca2+]i increase is verapamil sensitive. Phenylalkylamines bind with differing affinities to the basolateral and apical surfaces of principal cells in the main segment; however, dihydropyridine binds apically in the tubule initial segment. Immunocytochemical evidence suggests localization of alpha1-subunits to both basolateral and apical surfaces of principal cells in the tubule main segment. We suggest roles for L-type calcium channels and cGMP-mediated calcium influx in both calcium signaling and fluid transport mechanisms in Drosophila.
Assuntos
Canais de Cálcio/fisiologia , Cálcio/metabolismo , Proteínas de Drosophila , Proteínas de Insetos/fisiologia , Túbulos Renais/metabolismo , Neuropeptídeos/metabolismo , Oligopeptídeos/metabolismo , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio/efeitos dos fármacos , GMP Cíclico/farmacologia , Drosophila melanogaster , Inibidores Enzimáticos/farmacologia , Proteínas de Insetos/efeitos dos fármacos , Canais Iônicos/efeitos dos fármacos , Canais Iônicos/metabolismo , Túbulos Renais/citologia , Neuropeptídeos/efeitos dos fármacos , Nifedipino/farmacologia , Oligopeptídeos/efeitos dos fármacos , Ácido Pirrolidonocarboxílico/análogos & derivados , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Tapsigargina/farmacologia , Verapamil/farmacologiaRESUMO
Attempts were made to recover and serologically identify mycoplasmas from the lungs of 50 pigs with mycoplasmal pneumonia and from 50 lungs without gross evidence of pneumonia. Mycoplasma hyopneumoniae and M. hyorhinis were respectively cultured from 30% and 50% of pneumonic lungs and the former species was also recovered from 12% of non-pneumonic lungs. Three other isolates (one from pneumonic and two from non-pneumonic lungs) differed in colonial morphology from M. hyopneumoniae and M. hyorhinis. The viability of these isolates could not be maintained on subculture and they were not identified serologically. The indirect immunofluorescence test was found to be highly specific for the identification and differentiation of M. hyopneumoniae and M. hyorhinis.
