For the experiment, the excavation rate of individually marked workers kept in plastic cylinders filled with soil was recorded.
In that spirit, Naveen Sangji, sister of Sheri Sangji, the technician who last year died of injuries from lab fire at the University of California (UC), Los Angeles, made the issue of lab safety part of the official observances in April that marked Workers Memorial Day in Washington, D.C. Annual commemorations of job-related deaths have taken place for years, across the nation and abroad.
The mass of all marked workers was measured on each departure from and arrival to the nest to calculate the amount of nectar collected ( = net change in body mass).
During the first hour after exposure, behavioral repertoires expressed by the four marked workers were observed for 5 min in the 3.5 cm diameter field of view of a stereomicroscope (6.3× magnification) focused on the fungus garden, with 5 min intervals between each observation, resulting in 6 time points for the first hour.
In addition, for each of the two replicate observation colonies, we collected and pooled 20 non-paint marked workers in the act of the following five behaviors: nursing larvae, grooming larvae, engaged in trophallaxis with other workers, foraging for protein (collecting egg, mealworm, or liver), and foraging for carbohydrates (collecting honey solution).
Sixty of the marked workers from 5 colonies were collected on day 1, day 3, day 6, day 12, day 15 and day 20 in June, 2008, respectively, then anesthetized on ice and the HG was dissected using a binocular microscope.
The number of workers using the mandibular marking behavior (henceforth "marking workers") and the total number of mandibular marking behaviors (henceforth "marking") produced were recorded during 10 minutes before and 10 minutes after the introduction of the food resource or alien ant.
The latest PMI survey of Britain's manufacturing sector from the UK is out this morning too (9.30am) Most European stock markets are going to be closed today for a bank holiday to mark workers' rights.
During the first series of experiments we noted that the number of marking workers increased significantly after we deposited honey, prey or alien ants on the tested area (z = 5.303, 6.536 and 5.555, respectively; P<0.001 in all cases); (Fig. 2A).
The observers only had to enter a mark on a grid sheet (with 10 horizontal lines each corresponding to an eventual marking worker as during preliminary experiments we noted that it is very exceptional that more than 6 workers marked during the 10 minute period of time) each time a worker used the mandibular marking behavior.
In each colony we individually marked callow workers, returned them to their original colony and collected them 5 or 8 days later (QR group).
