Variation in the transition from inside to outside work in the red harvester ant Pogonomyrmex barbatus

Summary. In laboratory colonies of the red harvester ant, Pogonomyrmex barbatus, we observed the sequence of tasks performed by marked individuals. Observations of about 760 ants in three laboratory colonies indicate that ants often move from inside to outside work. However, there was a great deal of variation in the sequence. If trends in sequence were weak because ants do move from inside to outside work but the duration of our observations was too short to see the transition, ants should be observed to stay either inside or outside. There was no significant tendency for ants to persist in inside or outside work, indicating the variability in sequence is real. Ants tended to perform midden work before they died. Foraging activity is low in laboratory colonies, and it may be that ants that would be foragers in the field end up as midden workers in the laboratory. High variability in task sequence, in uniform laboratory conditions, contrasts with the apparently more consistent sequence from inside to outside work in the field. This suggests that requirements imposed by variable external conditions and colony needs in the field have a strong influence on task sequence.Received 7 May 2004; revised 11 November 2004; accepted 18 November 2004.     

Evaluation of methods for the estimation of mutation rates in cultured mammalian cell populations

A systematic comparison of 5 different statistical methods for the estimation of mutation rate (mu) in cultured Chinese hamster V79 cells is presented. Fluctuation tests were performed with several large batches of parallel cell cultures each allowed to grow for a different length of time in order to reach different population size (Nt). Based on Lea and Coulson's theoretical distribution, a comparison has been made between the experimental data and the expected distribution of the number of ouabain-resistant mutants per culture in these hamster cell populations. The sum of squared deviation between the observed and expected values, or SSD, was used as a means of the adequacy of the estimation method; the method which gives the smallest SSD is regarded as the best one for the estimation of mu. Our results show that when Nt is small, the occurrence of mutation is infrequent, and SSDs from different methods are similar. However, when Nt is large, there is a great discrepancy of the SSD values, suggesting a preference of using the maximum likelihood method, the Po method, the median method, the upper quartile method and the mean method, in that order, for the estimation of mu. The order of preference is correlated with estimation efficiencies. Depending on the size of Nt and the method used, the estimated mu may vary up to more than 3-fold. At a large Nt, the mu obtained from the maximum likelihood method is very precise. This suggests the importance of choosing an appropriate Nt as well as method for the estimation of mu.     

A model of a human recognition system with ‘thinking’

The human system of pattern recognition is explored. This system utilizes the method of syntactic feature comparison, activation of the patterns containing the feature, and sorting among the activated patterns. Both the pattern recognition process without thinking and with thinking are discussed, and examples are given. Contrary to the usual concept, the more complicated pattern has a better chance to be recognized correctly.A portion of this paper has been presented at the 1977 International Cybernetic Conference in Washington     

Formononetin,J1 and J2 have different effects on endothelial cells via EWSAT1‐TRAF6 and its downstream pathway

Formononetin is a natural isoflavone compound found mainly in Chinese herbal medicines such as astragalus and red clover. It is considered to be a typical phytooestrogen. In our previous experiments, it was found that formononetin has a two‐way regulatory effect on endothelial cells (ECs): low concentrations promote the proliferation of ECs and high concentrations have an inhibitory effect. To find a specific mechanism of action and provide a better clinical effect, we performed a structural transformation of formononetin and selected better medicinal properties for formononetin modifier J1 and J2 from a variety of modified constructs. The MTT assay measured the effects of drugs on human umbilical vein endothelial cell (HUVEC) activity. Scratch and transwell experiments validated the effects of the drugs on HUVEC migration and invasion. An in vivo assessment effect of the drugs on ovariectomized rats. Long‐chain non‐coding RNA for EWSAT1, which is abnormally highly expressed in HUVEC, was screened by gene chip, and the effect of the drug on its expression was detected by PCR after the drug was applied. The downstream factors and their pathways were analysed, and the changes in the protein levels after drug treatment were evaluated by Western blot. In conclusion, the mechanism of action of formononetin, J1 and J2 on ECs may be through EWSAT1‐TRAF6 and its downstream pathways.     

Three‐dimensional ring‐oven washing technique for a paper‐based immunodevice

Washing is a standard step for enzyme‐linked immunosorbent assays (ELISA) performed on a paper‐based chip, in which nonspecific‐binding antibodies and antigens should be removed completely from the paper surface. In this study, a novel three‐dimensional (3D) washing strategy using a heating ring‐oven was carried out on a paper‐based chip. Compared with a plane washing mode by a ring‐oven, this 3D washing strategy obtained a lower background, as gravity played an important role in the washing step. The paper‐based chip was placed on a 3D plastic holder and the waste area was connected to a heating ring. Use of a heating waste area meant that the nonspecific‐binding protein was continuously carried to the waste area through gravity and capillary action. The angle between the plastic holder and the ring plane was carefully selected. The effect of washing on different parts of the detection area was investigated by upconversion fluorescence and chemiluminescence (CL). This novel 3D washing strategy was performed for carcinoembryonic antigen detection through CL and a lower detection limit of 2 pg ml^?1 was obtained. This approach provides an effective washing strategy to remove nonspecific‐binding antibody from a paper‐based immunodevice.