An antibody raised against a peptide based on the C-terminal derived amino acid sequence from a cloned Drosophila melanogaster (fruit fly) gene, Rdl (resistant to dieldrin), was used to investigate localization of a GABA receptor subunit in adult male D. melanogaster. Many regions in the brain and thoracic ganglia were stained with this antibody. For example, staining was detected in the medulla, lobula and lobular plate optic neurpiles. Also stained were the antennal lobe glomeruli, the ellipsoid body of the central complex and the mushroom bodies. These results suggest possible roles for an RDL-like GABA receptor subunit in the processing of olfactory, visual and mechanosensory information in the nervous system of D. melanogaster.

Background: The stability of Alzheimer’s disease (AD) biomarkers in plasma, measured by immunomagnetic reduction (IMR) after long-term storage at –80°C, has not been established before. Method: Ninety-nine human plasma samples from 53 normal controls (NCs), 5 patients with amnestic mild cognitive impairment (aMCI), and 41 AD patients were collected. Each plasma sample was aliquoted and stored as single-use aliquots at –80°C. The baseline measurements for Aβ_1–40, Aβ_1–42, and total Tau protein (T-Tau) concentrations for each sample were done within 3 months of blood draw by IMR. They are referred to as baseline concentrations. A separate aliquot from each sample was assayed with IMR to assess the stability of the measured analytes during storage at –80°C between 1.1 and 5.4 years. This is referred to as a repeated result. Results: IMR shows that plasma levels of Aβ_1–40 and Aβ_1–42 exhibit stability over 5-year storage at –80°C and that plasma levels of T-Tau are less stable (approximately 1.5 years). Conclusion: Although the measured concentrations of T-Tau in human plasma may alter during storage, the diagnostic utility of the results are only slightly affected when the product of Aβ_1–42 and T-Tau concentrations are used. The results show that the overall agreement between baseline and repeated measurements in the ability of discriminating NCs from aMCI/AD patients is higher than 80%.