Table 1

Effects of anthrax LF on Xenopus oocyte maturation. Oocytes were isolated, defolliculated, injected, and induced to mature with progesterone as described (22). After progesterone-treated control oocytes had completed GVBD, oocytes were fixed and dissected to score GVBD. In experiment 1, LF was purified from culture supernatants of B. anthracis Sterne, a strain that produces PA, LF, and EF, with the use of methods described previously (23), and GVBD was scored by dissection 20 hours after progesterone treatment. In experiment 2, LF was produced as a recombinant fusion protein, PA20-LF, and cleaved with Factor X to release the PA20 domain (8). The expression host was B. anthracis lacking the EF gene. GVBD was scored 4 hours after progesterone treatment, when GVBD was complete in control oocytes. The injection buffer was 0.1 M KCl and 10 mM Hepes (pH 7.5).

Material injectedProgesterone treatmentGVBD*Frogs used (n)
Experiment 1
None0/1287
None+143/1587
Buffer+61/754
LF (1 ng)+24/523
LF (10 ng)+0/503
LF (40 ng)+0/754
LF E687C (40 ng)+57/734
Experiment 2
None0/993
None+108/1133
LF (40 ng)+0/753
Δ90 cyclin (24 ng)43/432
LF (40 ng), Δ90 cyclin (24 ng)75/753
  • * Proportion of oocytes injected that had undergone GVBD.