Many strains of the soil bacterium Bacillus subtilis are capable of producing and being resistant to the antibiotic sublancin because they harbor the Spb prophage. This 135 kb viral genome is integrated into the circular DNA chromosome of B. subtilis, and contains genes for the production of and resistance to sublancin. We investigated the role of SigY in sublancin production and resistance, finding that it is important for efficient maintenance of the Spb prophage. We were unable to detect the prophage in mutants lacking SigY. Additionally, these mutants were no longer able to produce sublancin, were sensitive to killing by this factor, and displayed a delay in sporulation. Wild-type cells with normal SigY activity were found to partially lose the Spb prophage during growth and early sporulation, suggesting a mechanism for the bistable outcome of sibling cells capable of killing and of being killed. The appropriate regulation of SigY appears to be essential for growth as evidenced by the inability to disrupt the gene for its putative antisigma. Our results confirm a role for SigY in antibiotic production and resistance, as has been found for other members of the extracytoplasmic function sigma factor family in B. subtilis, and shows that this role is achieved by affecting maintenance of the Spb prophage.

Successful ecdysis in insects depends on proper timing and sequential activation of an elaborate series of motor programs driven by a relatively conserved network of neuropeptides. The behaviors must be activated at the appropriate times to ensure successful loosening and shedding of the old cuticle, and can be influenced by environmental cues in the form of immediate sensory feedback and by circadian rhythms. We assessed the behaviors, components of the neural network and the circadian basis of ecdysis in the stick insect, Carausius morosus. C. morosus showed many of the characteristic pre-ecdysis and ecdysis behaviors previously described in crickets and locusts. Ecdysis was described in three phases, namely the (i) preparatory or pre-ecdysis phase, (ii) the ecdysial phase, and (iii) the post-ecdysis or exuvial phase. The frequencies of pushups and sways during the preparatory phase were quantified as well as durations of all the phases. The regulation of ecdysis appeared to act via elevation of cGMP, as described in many other insects, although eclosion hormone-like immunoreactivity was not noted using a lepidopteran antiserum. Finally, C. morosus showed a circadian rhythm to the onset of ecdysis, with ecdysis occurring just prior or at lights on. Ecdysis could be induced precociously with mechanical stimulation.

We have developed a machine vision-based method for automatically tracking deformations in the body wall to monitor ecdysis behaviors in the hornworm, Manduca sexta. The method utilizes naturally-occurring features on the animal's body (spiracles) and is highly accurate (>95% success in tracking). Moreover, it is robust to unanticipated changes in the animal's position and in lighting, and in the event tracking of specific features is lost, tracking can be reestablished within a few cycles without input from the user. We have paired our tracking technique with electromyography (EMG) and have also compared our in vivo results to fictive motor patterns recorded from isolated nerve cords. We found no major difference in the cycle periods of contractions during naturally-occurring ecdysis compared to ecdysis initiated prematurely through injection of the peptide Ecdysis-Triggering Hormone (ETH), and we confirmed that the ecdysis period in vivo is statistically similar to that of the fictive motor pattern.