Conditioned suppression of the proboscis-extension response in young, middle-aged, and old Drosophila melanogaster flies: Acquisition and extinction.

Young (7 days old), middle-aged (30 days old), and old (50 days old) Drosophila melanogaster males were used in an inhibitory conditioning of the proboscis-extension response. Two reinforcement schedules were applied, constant vs. partial. Partial reinforcement increased the number of trials needed to reach the learning criterion to the same extent in all age groups. Young flies needed fewer trials to reach the criterion than both middle-aged and old flies, which did not differ from each other. Extinction was delayed in the partial reinforcement groups by the same amount in all age groups. The slowest rate of extinction was observed in the old group and the fastest for the middle-aged flies. The results are discussed in connection with hypotheses that consider extinction an index either of behavioral rigidity or of strength of the initial learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of various extraction techniques for obtaining bioactive extracts from pine seeds

Evaluation was made of four extraction techniques (maceration with magnetic stirring, ultrasound-assisted extraction, microwave-assisted extraction, and extraction with pressurised liquids) to obtain polyphenolic extracts from pine seeds. The technique and temperature conditions that produce extracts containing the largest quantity of polyphenols were determined. Extraction assisted by microwave and extraction with pressurised liquids at temperatures >100 °C gave the best results. The correlation between the antioxidant activity of the extracts and the quantity of polyphenols that they contain has also been determined; a direct relationship between these two variables was found in the majority of extracts.The general biological activity of the extracts was also evaluated using the etiolated wheat coleoptile bioassay; extracts obtained with pressurised liquids, and with maceration under agitation, were the most bioactive. An inverse relationship between the degree of bioactivity and the extraction temperature was found.