Impact of Rap-Phr system abundance on adaptation of Bacillus subtilis

Microbes commonly display great genetic plasticity, which has allowed them to colonize all ecological niches on Earth. Bacillus subtilis is a soil-dwelling organism that can be isolated from a wide variety of environments. An interesting characteristic of this bacterium is its ability to form biofilms that display complex heterogeneity: individual, clonal cells develop diverse phenotypes in response to different environmental conditions within the biofilm. Here, we scrutinized the impact that the number and variety of the Rap-Phr family of regulators and cell-cell communication modules of B. subtilis has on genetic adaptation and evolution. We examine how the Rap family of phosphatase regulators impacts sporulation in diverse niches using a library of single and double rap-phr mutants in competition under 4 distinct growth conditions. Using specific DNA barcodes and whole-genome sequencing, population dynamics were followed, revealing the impact of individual Rap phosphatases and arising mutations on the adaptability of B. subtilis.

Molecular Aspects of Plant Growth Promotion and Protection by Bacillus subtilis

Bacillus subtilis is one of the most widely studied plant growth-promoting rhizobacteria. It is able to promote plant growth as well as control plant pathogens through diverse mechanisms, including the improvement of nutrient availability and alteration of phytohormone homeostasis as well as the production of antimicrobials and triggering induced systemic resistance, respectively. Even though its benefits for crop production have been recognized and studied extensively under laboratory conditions, the success of its application in fields varies immensely. It is widely accepted that agricultural application of B. subtilis often fails because the bacteria are not able to persist in the rhizosphere. Bacterial colonization of plant roots is a crucial step in the interaction between microbe and plant and seems, therefore, to be of great importance for its growth promotion and biocontrol effects. A successful root colonization depends thereby on both bacterial traits, motility and biofilm formation, as well as on a signal interplay with the plant. This review addresses current knowledge about plant-microbial interactions of the B. subtilis species, including the various mechanisms for supporting plant growth as well as the necessity for the establishment of the relationship.[Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 "No Rights Reserved" license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.

A sequential developmental field defect of the vertebrae, ribs, and sternum, in a young woman of the 12th century AD

Changes in the vertebral column are often noted in skeletal material. Descriptions of these anomalies are often lacking, and their developmental origins are not often discussed. The skeleton of a young woman from the medieval cemetery of Tirup, in Denmark, has multiple defects of the axial skeleton, including extra thoracic and lumbar vertebrae, border shifting, extra ribs, block vertebra, and deformed sternum. This case study is particularly interesting because of the number and diversity of anomalies seen; the rarity of these defects, even in living populations; and her survival to adult age. Careful analysis of the bones and use of the morphogenetic method of determining development stages has led to the conclusion that the initial defect probably occurred very early in development, during blastogenesis, with the initial development of at least two extra somitomeres in the paraxial mesoderm. These extra elements in turn led to problems in union and differentiation, and later chondrification and ossification of the vertebra. The malformations of the vertebrae also induced changes in the ribs and sternum. The initial error of segmentation is identified as a developmental field defect, and the cascade of anomalies seen is a developmental sequence caused by the initial field defect. The genetic and environmental causes of developmental field defects are reviewed.

Back pain distribution patterns: relationship to subjective measures of pain severity and disability

OBJECTIVE

To investigate the relationship between subjective pain measures and clinical subgroupings as determined by pain distribution patterns in back pain patients.

DESIGN

A prospective study using a computer-interview system.

SETTING

The Anglo-European College of Chiropractic outpatient clinic.

PATIENTS

Two hundred fourteen new patients with low back pain completed the computer back pain interview on their first or second visit to the clinic. No other inclusion criteria were applied.

MAIN OUTCOME MEASURES

Computer versions of the VAS, Oswestry and St. Thomas' disability questionnaires and the pain drawing.

RESULTS

Back pain patients with pain radiating below the knee (Group 3 patients) reported significantly higher levels of disability than patients with back pain alone (Group 1 patients) (p < .001) and back pain with pain referred to the buttock/thigh region (Group 2 patients) (p < .01). Similarly, Group 3 patients reported significantly higher levels of pain severity than both Group 1 (p < .01) and Group 2 (p < .05) patients. The increased level of disability reported by Group 3 patients almost exactly matched the increase in self-assessed pain severity. No differences were observed in the report of either pain severity or disability between Group 1 and Group 2 patients.

CONCLUSION

Subjective pain measure scores were shown to be related to recognizable clinical subgroupings of back pain based on the distribution, but not the extent, of the patient's pain. Back pain patients with radicular pain below the knee were found to be a high disability/pain severity group compared with other groups of back pain patients. More work is needed to investigate the potential of subjective pain measures in the differential diagnosis of back pain syndromes.

Authoring systems. Finding the right tool for your courseware development project

Many factors must be considered when selecting an appropriate tool for courseware development. An overview of development tools is provided. Based on the authors' experience in selecting an authoring system for a recent courseware development project, a practical process for selecting the appropriate tool is described. Considerations when determining the general needs for an authoring system and evaluating specific authoring systems' features are outlined. Selection considerations are also discussed.

Basaltic Cone Suggests Constructional Origin of Some Guyots

A basaltic cinder cone was built beneath the waters of Mono Lake in Pleistocene time. This cone is now exposed. Its internal structure, external form, and petrography suggest that it was constructed with a flat top.