Cytological Analysis of the Mother Cell Death Process during Sporulation in Bacillus subtilis

ABSTRACT We have identified the following events during the late stage in the mother cell in Bacillus subtilis: spore detachment from the polar site of the mother cell, membrane rupture, cell wall collapse, and release of the free spore. The membrane rupture was followed by mother cell lysis. Moreover, we found that NucB, an extracellular nuclease, is involved in DNA degradation after mother cell lysis.

Bacillary Hemoglobinuria: Induction by Liver Biopsy in Naturally and Experimentally Infected Animals

An outbreak of bacillary hemoglobinuria was precipitated by liver biopsy of calves from an area in which the disease was enzootic. Using the strain of Clostridium hemolyticum recovered from this outbreak, calves, ewes, and rabbits were inoculated intravenously or orally with a toxin-free spore suspension. Subsequent liver biopsy precipitated the disease in these animals. The characteristic focus of liver necrosis was regularly reproduced and appeared to be of toxic rather than ischemic origin.

CHEMICAL AND MORPHOLOGICAL STUDIES OF BACTERIAL SPORE FORMATION

From the stage of a completed membranous forespore to that of a fully ripened free spore, synchronously sporulating cells of a variant Bacillus cereus were studied by cytological and chemical methods. Particular attention was paid to the development of the three spore layers—cortex, coat, and exosporium—in relation to the forespore membrane. First, the cortex is laid down between the recently described (5) double layers of the forespore membrane. Then when the cortex is ⅓ fully formed, the spore coat and exosporium are laid down peripheral to the outer membrane layer covering the cortex. As these latter layers appear, the spores, previously dense by dark phase contrast, gradually "whiten" or show an increase in refractive index. With this whitening, calcium uptake commences, closely followed by the synthesis of dipicolinic acid and the process is terminated, an hour later, with the formation of a fully refractile spore. In calcium-deficient media, final refractility is lessened and dipicolinic acid is formed only in amounts proportional to the available calcium. If calcium is withheld during the period of uptake beyond a critical point, sporulating cells lose the ability to assimilate calcium and to form normal amounts of dipicolinic acid. The resulting deficient spores are liberated from the sporangia but are unstable in water suspensions. Unlike ripe spores, they do not react violently to acid hydrolysis and, in thin sections, their cytoplasmic granules continue to stain with lead solutions.