CHARACTERIZATION OF NITRIC OXIDE SYNTHASE IN THE BRAIN OF SPECIALIST AND PARASITIC SOLITARY BEES.

GALVANI GERÓNIMO L.; ROIG-ALSINA ARTURO; SETTEMBRINI BEATRIZ P.

New Orleans

Congreso; 42nd annual meeting of the Society for Neuroscience; 2012

Society for Neuroscience

Nitric oxide (NO) is recognized as a signaling molecule in the insect nervous system. Several experiments in Apis mellifera suggest an important role of this molecule in the processing of olfactory information as well as in learning and memory formation. Members of family Apidae show differences in the social structure and food source preference. In order to describe the properties of nitric oxide synthase (NOS) in solitary bees, we have used brains of males and females from different species: Apis mellifera workers (social, generalist); Melitoma segmentaria and Thygater analis (solitary, specialist); Leiopodus lacertinus and Doeringiella nobilis (solitary, parasitic). To localize the presence of NOS, we carried out immunocytochemistry and western blot experiments using a NOS antiserum directed to the C-terminal sequence of the enzyme which is conserved in most species (uNOS). Western blot analysis revealed a band at approximately 130 kDa in these species, which is in agreement with previous reports in bees. NOS activity was evaluated in brain homogenates by following, spectrophotometrically, the oxidation of oxyhemoglobin to methemoglobin (nmoles x min. mg. protein-1) In females the activity of the enzyme varied, being 4.71 in A. mellifera; 40.32 in M. segmentaria; 27.91 in T. analis; 7.08 in L. lacertinus and 16.90 in D. nobilis. In samples of male brains the values of NOS activity were 18.29 in M. segmentaria, 22.2 in T. analis and 15.76 in L. lacertinus. In brain sections, the NADPH diaphorase assay marked somata in the cell body layers of the medial and lateral calyces of the mushroom bodies of A. mellifera, M. segmentaria and T. analis. The pedunculus and the basal ring were also stained. On the contrary this histochemical technique showed scarce or no labeling at all in L. lacertinus and D. nobilis. uNOS antiserum labeled a few somata located around the antennal lobe in female brains. These results suggest that NO production is mainly present in the olfactory brain areas. Females of specialist bees showed higher levels of NOS activity than parasitic bees. In conclusion, NO might be related with the detection and processing of olfactory information during foraging.