Under certain circumstances, the collision of magnetic monopoles, topologically locked-in regions of false vacuum, leads to topological inflation and the creation of baby universes. The future evolution of initial data represented by the two incoming monopoles may contain a timelike singularity but this need not be the case. We discuss the global structure of the spacetime associated with monop...

During spore formation in Bacillus subtilis, cell division occurs at the cell pole and is believed to require essentially the same division machinery as vegetative division. Intriguingly, although the cell division protein DivIB is not required for vegetative division at low temperatures, it is essential for efficient sporulation under these conditions. We show here that at low temperatures in ...

PORULATION of diploids of Saccharomyces cerevisiae involves meiosis and subsequent ascospore formation. The genetic and physiological control of this process is of interest as a model system for the control of meiosis and gametogenesis and has been the subject of several reviews (FOWELL 1969; HABER and HALVORSON 1972; TINGLE et al. 1973). Study of meiosis and gamete formation at the biochemical...

Quiescence or dormancy plays an important role in biological systems, from spore formation in bacteria to predator-prey cycles. In a mathematical framework, quiescence is modeled by diffusive coupling of the active dynamics to quiescent phases. Although coupling a given vector field to the zero field may appear simple at first glance, quiescent phases have biologically relevant effects which ca...

Phage phi29 is a virulent phage of Bacillus subtilis with no known lysogenic cycle. Indeed, lysis occurs rapidly following infection of vegetative cells. Here, we show that phi29 possesses a powerful strategy that enables it to adapt its infection strategy to the physiological conditions of the infected host to optimize its survival and proliferation. Thus, the lytic cycle is suppressed when th...

Bacillus subtilis chooses between matrix production and spore formation, which are both controlled by the regulator Spo0A~P. We report that metabolism and chromosome copy number dictate which fate is adopted. Conditions that favour low Spo0A~P levels promote matrix production, whereas conditions favouring high levels trigger sporulation. Spo0A~P directs the synthesis of SinI, an antirepressor f...

An egg yolk-polymyxin medium (KG) for rapid enumeration of Bacillus cereus is described. The test is presumptive in that differentiation of B. cereus (and closely related organisms) from other species is based on the formation of turbidity in the agar surrounding the colonies of the cereus group organisms. The medium is formulated to encourage sporulation and release of free spores for serologi...

Spontaneous release of the temperate bacteriophage T (phiT), carried by Bacillus megaterium 899a, occurred during early growth of the host cells. Rejuvenated cells (accomplished by a 5x dilution in fresh medium) and unrejuvenated cells were induced by mitomycin C during the course of sporulation and subsequent phage phiT production measured by burst size. Induction of sequential samples of unre...

DNA transposons represent an essential tool in the armoury of the molecular microbiologist. We previously developed a catP-based mini transposon system for Clostridium difficile in which the expression of the transposase gene was dependent on a sigma factor unique to C. difficile, TcdR. Here we have shown that the host range of the transposon is easily extended through the rapid chromosomal ins...

The effects of low temperature on morphogenesis and cellular differentiation of Dictyostelium discoideum were examined. During incubation at 5 degrees C, the vegetative and preaggregation cells never developed, but cell masses at the aggregation or slug stage developed to form hemispherical, or dumbbell-shaped multicellular structures. By staining with FITC-antispore IgG, the structures formed ...