Isolation of Monoaminergic Synaptosomes from Rat Brain by Immunomagnetophoresis

Monoaminergic synaptosomes have been isolated and purified from rat brain by immunomagnetophoresis. This novel technique uses magnetic beads to which Protein A is bound. Noradrenergic, dopaminergic, and serotonergic synaptosomes (previously cell-surface labelled with anti-dopamine-beta-hydroxylase, anti-tyrosine hydroxylase, and anti-tryptophan hydroxylase, respectively) may be isolated in a highly purified state. The synaptosomal subpopulations are recovered in a viable metabolic state and show glucose-stimulated respiration and Ca2(+)-dependent neurotransmitter release. A novel subtype of dopamine-beta-hydroxylase was found in dopaminergic terminals. No evidence for glutamate corelease from monoaminergic synaptosomes was obtained.     

The impact of local population genetic background on the spread of the selfish element Medea‐1 in red flour beetles

Selfish genetic elements have been found in the genomes of many species, yet our understanding of their evolutionary dynamics is only partially understood. A number of distinct selfish Medea elements are naturally present in many populations of the red flour beetle (Tribolium castaneum). Although these Medea elements are predicted by models to increase in frequency within populations because any offspring of a Medea‐bearing mother that do not inherit at least one Medea allele will die, experiments demonstrating an increase in a naturally occurring Medea element are lacking. Our survey of the specific Medea element, M¹, in the United States showed that it had a patchy geographic distribution. From the survey, it could not be determined if this distribution was caused by a slow process of M¹ colonization of discrete populations or if some populations lacked M¹ because they had genetic factors conferring resistance to the Medea mechanism. We show that populations with naturally low to intermediate M¹ frequencies likely represent transient states during the process of Medea spread. Furthermore, we find no evidence that genetic factors are excluding M¹ from US populations where the element is not presently found. We also show how a known suppressor of Medea can impair the increase of M¹ in populations and discuss the implications of our findings for pest‐management applications of Medea elements.     

Assembly of splicing complexes on exon 11 of the human insulin receptor gene does not correlate with splicing efficiency in-vitro

Background  

Incorporation of exon 11 of the insulin receptor gene is both developmentally and hormonally-regulated. Previously, we have shown the presence of enhancer and silencer elements that modulate the incorporation of the small 36-nucleotide exon. In this study, we investigated the role of inherent splice site strength in the alternative splicing decision and whether recognition of the splice sites is the major determinant of exon incorporation.