Dynamic aspects of the structured cell population in a swarming colony of Proteus mirabilis.

Proteus mirabilis forms a concentric-ring colony by undergoing periodic swarming. A colony in the process of such synchronized expansion was examined for its internal population structure. In alternating phases, i.e., swarming (active migration) and consolidation (growth without colony perimeter expansion), phase-specific distribution of cells differing in length, in situ mobility, and migration ability on an agar medium were recognized. In the consolidation phase, the distribution of mobile cells was restricted to the inner part of a new ring and a previous terrace. Cells composing the outer part of the ring were immobile in spite of their ordinary swimming ability in a viscous solution. A sectorial cell population having such an internal structure was replica printed on fresh agar medium. After printing, a transplant which was in the swarming phase continued its ongoing swarming while a transplanted consolidation front continued its scheduled consolidation. This shows that cessation of migration during the consolidation phase was not due to substances present in the underlying agar medium. The ongoing swarming schedule was modifiable by separative cutting of the swarming front or disruption of the ring pattern by random mixing of the pattern-forming cell population. The structured cell population seemed to play a role in characteristic colony growth. However, separation of a narrow consolidation front from a backward area did not induce disturbance in the ongoing swarming schedule. Thus, cells at the frontal part of consolidation area were independent of the internal cell population and destined to exert consolidation and swarming with the ongoing ordinary schedule.

Expression of histamine receptors in nasal epithelial cells and endothelial cells--the effects of sex hormones.

BACKGROUND: Hyperreactivity of the nasal mucosa is a characteristic of nasal allergy. During pregnancy, aggravation of nasal allergic symptoms is occasionally observed in subjects with nasal allergy. METHODS: Using the reverse transcription-polymerase chain reaction and Southern blot hybridization method, we investigated histamine H1 receptor mRNA (H1R mRNA) expressions in specimens of nasal epithelial layer obtained by scraping, as well as cultured human nasal epithelial cells (HNECs) and human mucosal microvascular endothelial cells (HMMECs). We compared the expressions on the specimens from patients with nasal allergy with those with nonallergic rhinitis or those from normal volunteers. In addition, we investigated the effects of female hormones on the H1R mRNA expressions in HNECs and HMMECs. RESULTS: H1R mRNA was detected in scraped specimens of nasal epithelial layer, as well as in HNECs and HMMECs. The mRNA expressions in nasal mucosal scraped specimens of epithelial layers and HNECs were more marked in patients with nasal allergy than in the other two groups. In addition, the present study demonstrates that the female hormones beta-estradiol and progesterone significantly increase the expressions of H1R mRNA on HNECs and HMMECs. CONCLUSION: The increase of the expressions of H1R mRNA may explain, in part, the nasal hyperreactivity to histamine observed in patients with nasal allergy. It has also been suggested that sex hormones are related to the preponderance of females in the incidence of allergic rhinitis after puberty, and that they are related, at least partially, to the aggravation of the nasal hyperreactivity symptoms during pregnancy through the enhanced expression of H1R mRNA on HNECs and HMMECs.