Table 5

A soluble bacterial product limits life span extension by BD.

A.

Cohort

n

Mean Survival

Median Survival

% extension of Median

p-value

CF

110

25.1 ± 0.5

23

-

-

BD

74

34.3 ± 0.9

34

48

1.4 × 10^-15

BD + LB

94

35.9 ± 0.8

37

61

1.4 × 10^-19

BD + sup

116

30.2 ± 0.8

31

35

2.3 × 10^-07

Agar Barrier

113

29.6 ± 0.8

31

35

4.0 × 10^-05

B.

CF

BD

BD + LB

BD + sup

Agar Barrier

CF

-

1.4E-13

1.4E-19

2.3E-07

4.0E-05

BD

-

-

2.6E-01

1.0E-03

7.7E-04

BD + LB

-

-

-

2.2E-06

2.6E-06

BD + sup

-

-

-

-

6.4E-01

Agar Barrier

-

-

-

-

-

Life span was measured for N2 on plates with food (control fed, CF), plates without food (bacterial deprivation, BD), BD plates treated with LB (BD + LB) or cell-free supernatant from an E. coli OP50 culture (BD + sup), or plates containing a lawn of E. coli OP50 beneath the surface of the agar (Agar Barrier). (A) The number of animals (n), mean survival (± standard error, SE), median survival, percent extension of the median, and p-values are given for each strain and condition. Data shown here are pooled from two independent trials. P-values were calculated by the Wilcoxon Rank-Sum test using the MATLAB 'ranksum' function. (B) Pair-wise comparisons to test for significant differences between median life span were made for each experimental condition and p-values are given for each pair.

Smith et al. BMC Developmental Biology 2008 8:49   doi:10.1186/1471-213X-8-49