Preventive and restorative alternatives to caries by irradiation: a scoping review.

PURPOSE: This study is to conduct a comprehensive scoping review to map scientific evidence and clarify concepts regarding the commonly recommended preventive and restorative dental treatments for patients diagnosed with head and neck cancer (HNC) and subjected to radiotherapy. MATERIAL AND METHODS: This systematic scoping review was performed under the PRISMA-ScR guidelines. The study's experimental design was registered in the Open Science Framework. In vitro studies that evaluated preventive and restorative dental treatment over 50 Gy radiation doses were included. The search was conducted in November 2023 in five electronic databases (PubMed, Scopus, Web of Science, Cochrane Library, and Embase) without language or date restriction. A search strategy was applied based on keywords, MeSh terms, or synonyms. A descriptive analysis was conducted. RESULTS: A total of 49 studies, out of 3679 original articles identified, were included and reviewed. Of the included studies, three evaluated saliva stimulants and 35 evaluated fluoride-based preventive materials: gel (n = 18) toothpaste (n = 11) mouth rinse (n = 8) and varnish (n = 5) while 14 evaluated restorative materials: resin composite (n = 12) glass ionomer cement (n = 6) and amalgam (n = 1) Of those studies, 36 were clinical trials and 13 were in vitro studies. CONCLUSION: Fluoride gel was the most frequently recommended preventive material for preventing radiation caries with supportive clinical evidence. Resin composite and glass ionomer were the most frequently used restorative materials, respectively. However, there is not yet clinical evidence to support the use of resin composite in irradiated teeth.

Effect of educational intervention on computer-aided-design and computer-aided-manufacturing technology to preclinical dental students.

INTRODUCTION: This study evaluated the effectiveness of a video presentation instruction compared to the prevailing traditional lecture provided in the preclinical classroom when introducing computer-aided design/computer-aided manufacturing (CAD/CAM) technology. MATERIALS AND METHODS: This study was conducted as a controlled educational trial (single-blind) on 120 first-year dental students. Students were assigned to two learning groups: the control (n = 60, traditional lecture) and the intervention (n = 60, video presentation). Both groups completed a self-efficacy scale (SES) survey before instruction. Then, the intervention group actively participated in a one-session video presentation while the control group was given a traditional lecture. After the presentations, student knowledge was assessed with a hands-on simulated exercise that was scored out of 60 points. At last, students completed a post-instruction student perception and attitude (SPA) survey. Inferential hypothesis testing was conducted with two-sample t-tests, and significance was defined as p ≤ .05. RESULTS: There were no significant differences in the student pre-instruction SES scores between the control and intervention groups. After the video learning, CAD/CAM knowledge application during the hands-on simulated exercise showed significantly higher results in the intervention group as the assessment scores from the intervention group averaged 13.6 ± 2.0 points higher than the control group (p < .001). The results from the post-instruction SPA survey showed no statistically significant difference between groups. CONCLUSION: With the video presentation technique, our first-year dental students were able to greatly enhance their CAD/CAM application skills. The results from this study could be applied at other dental educational institutions with potential similar outcomes.

Analysis of different factors on dental students' perception of a flipped classroom model: A 6-year follow-up study.

INTRODUCTION: To evaluate different factors affecting two different cohorts of dental students' perceptions with the flipped classroom (FC) model in a preclinical dental course over six years. MATERIALS AND METHODS: In 2016 (cohort #1) and 2022 (cohort #2), second-year dental students participated in FC model in a preclinical dental course consisting of pre-class recorded videos and lectures along with classroom interactive exercises. Students then completed an anonymous pen-and-paper survey evaluating three factors influencing students' overall study experience with the FC model. Survey responses from cohort #1 and cohort #2 were compared to assess the effect of generation, student demographics and COVID-19 pandemic on students' perceptions. RESULTS: When asked to rate the FC experience out of 5, the mean ratings of cohort #1 and cohort #2 were 4.3 (±0.9) and 4.0 (±0.8), respectively. Cohort #2 preferred viewing slides and videos prior to class and had a higher agreement that pre-class course materials were beneficial to class preparation. Conversely, cohort #1 had a higher agreement that in-class discussion and exercises helped them to learn course content. From cohort #2, 88.6% of males and 71.6% of females preferred the FC approach over traditional lecture. CONCLUSION: Both cohorts reported positively with the FC model of teaching. Cohort #2 had higher positive reports with the pre-class work and cohort #1 had a higher positive report with in-class work. Course design should reflect the students' points of view and learning perspectives with careful consideration of the student population in the classroom.

Deficient autophagy in epithelial stem cells drives aging in the freshwater cnidarian Hydra.

Hydra possesses three distinct stem cell populations that continuously self-renew and prevent aging in Hydra vulgaris However, sexual animals from the H. oligactis cold-sensitive strain Ho_CS develop an aging phenotype upon gametogenesis induction, initiated by the loss of interstitial stem cells. Animals stop regenerating, lose their active behaviors and die within 3 months. This phenotype is not observed in the cold-resistant strain Ho_CR To dissect the mechanisms of Hydra aging, we compared the self-renewal of epithelial stem cells in these two strains and found it to be irreversibly reduced in aging Ho_CS but sustained in non-aging Ho_CR We also identified a deficient autophagy in Ho_CS epithelial cells, with a constitutive deficiency in autophagosome formation as detected with the mCherry-eGFP-LC3A/B autophagy sensor, an inefficient response to starvation as evidenced by the accumulation of the autophagosome cargo protein p62/SQSTM1, and a poorly inducible autophagy flux upon proteasome inhibition. In the non-aging H. vulgaris animals, the blockade of autophagy by knocking down WIPI2 suffices to induce aging. This study highlights the essential role of a dynamic autophagy flux to maintain epithelial stem cell renewal and prevent aging.

Dynamic growth QTL action in diverse light environments: characterization of light regime-specific and stable QTL in Arabidopsis.

Plant growth is a complex process affected by a multitude of genetic and environmental factors and their interactions. To identify genetic factors influencing plant performance under different environmental conditions, vegetative growth was assessed in Arabidopsis thaliana cultivated under constant or fluctuating light intensities, using high-throughput phenotyping and genome-wide association studies. Daily automated non-invasive phenotyping of a collection of 382 Arabidopsis accessions provided growth data during developmental progression under different light regimes at high temporal resolution. Quantitative trait loci (QTL) for projected leaf area, relative growth rate, and PSII operating efficiency detected under the two light regimes were predominantly condition-specific and displayed distinct temporal activity patterns, with active phases ranging from 2 d to 9 d. Eighteen protein-coding genes and one miRNA gene were identified as potential candidate genes at 10 QTL regions consistently found under both light regimes. Expression patterns of three candidate genes affecting projected leaf area were analysed in time-series experiments in accessions with contrasting vegetative leaf growth. These observations highlight the importance of considering both environmental and temporal patterns of QTL/allele actions and emphasize the need for detailed time-resolved analyses under diverse well-defined environmental conditions to effectively unravel the complex and stage-specific contributions of genes affecting plant growth processes.

Temporal dynamics of QTL effects on vegetative growth in Arabidopsis thaliana.

We assessed early vegetative growth in a population of 382 accessions of Arabidopsis thaliana using automated non-invasive high-throughput phenotyping. All accessions were imaged daily from 7 d to 18 d after sowing in three independent experiments and genotyped using the Affymetrix 250k SNP array. Projected leaf area (PLA) was derived from image analysis and used to calculate relative growth rates (RGRs). In addition, initial seed size was determined. The generated datasets were used jointly for a genome-wide association study that identified 238 marker-trait associations (MTAs) individually explaining up to 8% of the total phenotypic variation. Co-localization of MTAs occurred at 33 genomic positions. At 21 of these positions, sequential co-localization of MTAs for 2-9 consecutive days was observed. The detected MTAs for PLA and RGR could be grouped according to their temporal expression patterns, emphasizing that temporal variation of MTA action can be observed even during the vegetative growth phase, a period of continuous formation and enlargement of seemingly similar rosette leaves. This indicates that causal genes may be differentially expressed in successive periods. Analyses of the temporal dynamics of biological processes are needed to gain important insight into the molecular mechanisms of growth-controlling processes in plants.

The Development and Implementation of Preventive Medicine Resident Rotations in a Shelter Serving Asylum-Seekers at the US-Mexico Border.

Asylum-seekers present to the US-Mexico border with a variety of acute health needs. In December 2018, the County of San Diego Health and Human Services Agency partnered with the University of California, San Diego to provide health screenings to asylum-seekers at a humanitarian shelter administered by Jewish Family Services. The assessments screened for communicable diseases and acute conditions. Preventive medicine residents in the HRSA-funded UCSD-SDSU (University of California, San Diego-San Diego State University) Residency were trained to become an integral part of the program. Training included cultural competency, public health interface, protocol development and implementation, interdisciplinary teamwork, and quality improvement. Over 18 months, nearly 20000 asylum-seekers were screened, which allowed for the detection of an imported influenza outbreak and prevented any major public health incidents or medical errors. This health screening program for asylum-seekers provided an important experience for preventive medicine trainees. In turn, preventive medicine and other trainees were valuable contributors to the program.

Genetic diversity for nitrogen use efficiency in Arabidopsis thaliana.

MAIN CONCLUSION: The plasticity of plant growth response to differing nitrate availability renders the identification of biomarkers difficult, but allows access to genetic factors as tools to modulate root systems to a wide range of soil conditions. Nitrogen availability is a major determinant of crop yield. While the application of fertiliser substantially increases the yield on poor soils, it also causes nitrate pollution of water resources and high costs for farmers. Increasing nitrogen use efficiency in crop plants is a necessary step to implement low-input agricultural systems. We exploited the genetic diversity present in the worldwide Arabidopsis thaliana population to study adaptive growth patterns and changes in gene expression associated with chronic low nitrate stress, to identify biomarkers associated with good plant performance under low nitrate availability. Arabidopsis accessions were grown on agar plates with limited and sufficient supply of nitrate to measure root system architecture as well as shoot and root fresh weight. Differential gene expression was determined using Affymetrix ATH1 arrays. We show that the response to differing nitrate availability is highly variable in Arabidopsis accessions. Analyses of vegetative shoot growth and root system architecture identified accession-specific reaction modes to cope with limited nitrate availability. Transcription and epigenetic factors were identified as important players in the adaption to limited nitrogen in a global gene expression analysis. Five nitrate-responsive genes emerged as possible biomarkers for NUE in Arabidopsis. The plasticity of plant growth in response to differing nitrate availability in the substrate renders the identification of morphological and molecular features as biomarkers difficult, but at the same time allows access to a multitude of genetic factors which can be used as tools to modulate and adjust root systems to a wide range of soil conditions.

Salt-sensitivity of σ(H) and Spo0A prevents sporulation of Bacillus subtilis at high osmolarity avoiding death during cellular differentiation.

The spore-forming bacterium Bacillus subtilis frequently experiences high osmolarity as a result of desiccation in the soil. The formation of a highly desiccation-resistant endospore might serve as a logical osmostress escape route when vegetative growth is no longer possible. However, sporulation efficiency drastically decreases concomitant with an increase in the external salinity. Fluorescence microscopy of sporulation-specific promoter fusions to gfp revealed that high salinity blocks entry into the sporulation pathway at a very early stage. Specifically, we show that both Spo0A- and SigH-dependent transcription are impaired. Furthermore, we demonstrate that the association of SigH with core RNA polymerase is reduced under these conditions. Suppressors that modestly increase sporulation efficiency at high salinity map to the coding region of sigH and in the regulatory region of kinA, encoding one the sensor kinases that activates Spo0A. These findings led us to discover that B. subtilis cells that overproduce KinA can bypass the salt-imposed block in sporulation. Importantly, these cells are impaired in the morphological process of engulfment and late forespore gene expression and frequently undergo lysis. Altogether our data indicate that B. subtilis blocks entry into sporulation in high-salinity environments preventing commitment to a developmental program that it cannot complete.

Impact of tofacitinib treatment on human B-cells in vitro and in vivo.

B-cells are pivotal to the pathogenesis of rheumatoid arthritis and tofacitinib, a JAK inhibitor, is effective and safe in its treatment. Tofacitinib interferes with signal transduction via cytokine receptors using the common γ-chain. Despite extensive data on T-lymphocytes, the impact of tofacitinib on B-lymphocytes is poorly understood. In this study we assessed the effect of tofacitinib on B-lymphocyte differentiation and function. Tofacitinib treatment strongly impaired in vitro plasmablast development, immunoglobulin secretion and induction of B-cell fate determining transcription factors, Blimp-1, Xbp-1, and IRF-4, in naïve B-cells. Interestingly, class switch and activation-induced cytidine deaminase (AICDA) induction was only slightly reduced in activated naïve B-cells. The effect of tofacitinib on plasmablast formation, immunoglobulin secretion and proliferation was less profound, when peripheral blood B-cells, including not only naïve but also memory B-cells, were stimulated. In line with these in vitro results, the relative distribution of B-cell populations remained stable in tofacitinib treated patients. Nevertheless, a temporary increase in absolute B-cell numbers was observed 6-8 weeks after start of treatment. In addition, B-cells isolated from tofacitinib treated patients responded rapidly to in vitro activation. We demonstrate that tofacitinib has a direct impact on human naïve B-lymphocytes, independently from its effect on T-lymphocytes, by impairing their development into plasmablasts and immunoglobulin secretion. The major effect of tofacitinib on naïve B-lymphocyte development points to the potential inability of tofacitinib-treated patients to respond to novel antigens, and suggests planning vaccination strategies prior to tofacitinib treatment.

Non-canonical structure, function and phylogeny of the Bsister MADS-box gene OsMADS30 of rice (Oryza sativa).

Bsister MADS-box genes play key roles in female reproductive organ and seed development throughout seed plants. This view is supported by their high conservation in terms of sequence, expression and function. In grasses, there are three subclades of Bsister genes: the OsMADS29-, the OsMADS30- and the OsMADS31-like genes. Here, we report on the evolution of the OsMADS30-like genes. Our analyses indicate that these genes evolved under relaxed purifying selection and are rather weakly expressed. OsMADS30, the representative of the OsMADS30-like genes from rice (Oryza sativa), shows strong sequence deviations in its 3' region when compared to orthologues from other grass species. We show that this is due to a 2.4-kbp insertion, possibly of a hitherto unknown helitron, which confers a heterologous C-terminal domain to OsMADS30. This putative helitron is not present in the OsMADS30 orthologues from closely related wild rice species, pointing to a relatively recent insertion event. Unlike other Bsister mutants O. sativa plants carrying a T-DNA insertion in the OsMADS30 gene do not show aberrant seed phenotypes, indicating that OsMADS30 likely does not have a canonical 'Bsister function'. However, imaging-based phenotyping of the T-DNA carrying plants revealed alterations in shoot size and architecture. We hypothesize that sequence deviations that accumulated during a period of relaxed selection in the gene lineage that led to OsMADS30 and the alteration of the C-terminal domain might have been a precondition for a potential neo-functionalization of OsMADS30 in O. sativa.

Obesity-induced oxidative stress, accelerated functional decline with age and increased mortality in mice.

Obesity is a serious chronic disease that increases the risk of numerous co-morbidities including metabolic syndrome, cardiovascular disease and cancer as well as increases risk of mortality, leading some to suggest this condition represents accelerated aging. Obesity is associated with significant increases in oxidative stress in vivo and, despite the well-explored relationship between oxidative stress and aging, the role this plays in the increased mortality of obese subjects remains an unanswered question. Here, we addressed this by undertaking a comprehensive, longitudinal study of a group of high fat-fed obese mice and assessed both their changes in oxidative stress and in their performance in physiological assays known to decline with aging. In female C57BL/6J mice fed a high-fat diet starting in adulthood, mortality was significantly increased as was oxidative damage in vivo. High fat-feeding significantly accelerated the decline in performance in several assays, including activity, gait, and rotarod. However, we also found that obesity had little effect on other markers of function and actually improved performance in grip strength, a marker of muscular function. Together, this first comprehensive assessment of longitudinal, functional changes in high fat-fed mice suggests that obesity may induce segmental acceleration of some of the aging process.

Hydra, a powerful model for aging studies.

Cnidarian Hydra polyps escape senescence, most likely due to the robust activity of their three stem cell populations. These stem cells continuously self-renew in the body column and differentiate at the extremities following a tightly coordinated spatial pattern. Paul Brien showed in 1953 that in one particular species, Hydra oligactis, cold-dependent sexual differentiation leads to rapid aging and death. Here, we review the features of this inducible aging phenotype. These cellular alterations, detected several weeks after aging was induced, are characterized by a decreasing density of somatic interstitial cell derivatives, a disorganization of the apical nervous system, and a disorganization of myofibers of the epithelial cells. Consequently, tissue replacement required to maintain homeostasis, feeding behavior, and contractility of the animal are dramatically affected. Interestingly, this aging phenotype is not observed in all H. oligactis strains, thus providing a powerful experimental model for investigations of the genetic control of aging. Given the presence in the cnidarian genome of a large number of human orthologs that have been lost in ecdysozoans, such approaches might help uncover novel regulators of aging in vertebrates.

Structural reevaluation of Streptococcus pneumoniae Lipoteichoic acid and new insights into its immunostimulatory potency.

Streptococcus pneumoniae is a Gram-positive human pathogen with a complex lipoteichoic acid (pnLTA) structure. Because the current structural model for pnLTA shows substantial inconsistencies, we reinvestigated purified and, more importantly, O-deacylated pnLTA, which is most suitable for NMR spectroscopy and electrospray ionization-MS spectrometry. We analyzed pnLTA of nonencapsulated pneumococcal strains D39Δcps and TIGR4Δcps, respectively. The data obtained allowed us to (re)define (i) the position and linkage of the repeating unit, (ii) the putative α-GalpNAc substitution at the ribitiol 5-phosphate (Rib-ol-5-P), and (iii) the length of (i.e. the number of repeating units in) the pnLTA chain. We here also describe for the first time that the terminal sugar residues in the pnLTA (Forssman disaccharide; α-D-GalpNAc-(1→3)-ß-D-GalpNAc-(1→)), responsible for the cross-reactivity with anti-Forssman antigen antibodies, can be heterogeneous with respect to its degree of phosphorylcholine substitution in both O-6-positions. To assess the proinflammatory potency of pnLTA, we generated a (lipopeptide-free) Δlgt mutant of strain D39Δcps, isolated its pnLTA, and showed that it is capable of inducing IL-6 release in human mononuclear cells, independent of TLR2 activation. This finding was quite in contrast to LTA of the Staphylococcus aureus SA113Δlgt mutant, which did not activate human mononuclear cells in our experiments. Remarkably, this is also contrary to various other reports showing a proinflammatory potency of S. aureus LTA. Taken together, our study refines the structure of pnLTA and indicates that pneumococcal and S. aureus LTAs differ not only in their structure but also in their bioactivity.

Bioavailability and allergoprotective capacity of milk-associated conjugated linoleic acid in a murine model of allergic airway inflammation.

BACKGROUND: Cross-sectional epidemiological studies have demonstrated that farm milk from traditional farm settings possesses allergoprotective properties. Up to now, it has not been clarified which milk ingredient is responsible for protection against allergic diseases. As farm milk is rich in conjugated linoleic acids (CLA), it is hypothesized that this n-3 polyunsaturated fatty acid family contributes to the allergoprotective capacity of farm milk. We aim to prove this hypothesis in a murine model of allergic airway inflammation. METHODS: To prove the bioavailability and allergoprotective capacity of milk-associated CLA in a standardized protocol, milk batches that differed significantly in terms of their CLA content were spray dried and incorporated into a basic diet by substituting the regular sunflower fat fraction. Initially, the milk CLA uptake from the diet was monitored via measurement of the CLA content in plasma and erythrocyte membranes obtained from supplemented mice. To determine whether a milk CLA-enriched diet possesses allergoprotective properties, female Balb/c mice were fed the milk CLA-enriched diet ahead of sensitization and a challenge with ovalbumin (OVA) and the parameters of airway inflammation and eisosanoid pattern were measured. RESULTS: In animals, supplementation with a diet rich in milk CLA resulted in elevated CLA levels in plasma and erythrocyte membranes, indicating bioavailability of milk fatty acids. Though membrane-associated phospholipid patterns were affected by supplementation with milk CLA, this application neither reduced the hallmarks of allergic airway inflammation in sensitized and OVA-challenged mice nor modified the eiconsanoid pattern in the bronchoalveolar lavage fluid of these animals. CONCLUSION: Milk-associated CLA was not capable of preventing murine allergic airway inflammation in an animal model of OVA-induced allergic airway inflammation.

Nanostructure-mediated transport of biologics across epithelial tissue: enhancing permeability via nanotopography.

Herein, we demonstrate that nanotopographical cues can be utilized to enable biologics >66 kDa to be transported across epithelial monolayers. When placed in contact with epithelial monolayers, nanostructured thin films loosen the epithelial barrier and allow for significantly increased transport of FITC-albumin, FITC-IgG, and a model therapeutic, etanercept. Our work highlights the potential to use drug delivery systems which incorporate nanotopography to increase the transport of biologics across epithelial tissue.

Effects of simulation-based flipped classroom in developing head and neck examination skills in dental students.

OBJECTIVES: To evaluate the effectiveness of a simulation-based flipped classroom in developing dental students' head and neck examination skills. METHODS: Second-year dental students (n = 118) participated in a simulation-based flipped classroom experience. A pre-class recorded lecture and video were posted online one week before the simulation date. In class, students completed a pre-quiz assessing pre-class coursework understanding of head and neck examination content. Then, students attended a question-and-answer session before the patient simulation. A formative assessment of head and neck examination simulation on a patient in the clinic was completed. Lastly, students completed an in-class post-quiz assessing understanding of head and neck examination content after the simulation, classroom simulation discussion, and open-response survey. RESULTS: Student post-quiz scores were significantly higher than pre-quiz scores, with an average improvement of 4.8 ± 7.2 percentage points. There was no difference between male and female improvement in scores. Student survey responses indicated that students liked combining simulation and flipped classroom methodology, flexibility with their schedules, learning at their pace, and opportunities for a deeper level of learning. Students reported wanting more practice sessions for their technical skills and more accessibility to faculty. CONCLUSIONS: According to this study's results, students had significantly higher post-quiz scores than pre-quiz scores and reported positive perceptions of this combined teaching technique. A simulation-based flipped classroom might be an effective teaching approach for developing head and neck examination skills that can be applied at other dental facilities with potentially similar results.

Filtered back projection vs. iterative reconstruction for CBCT: effects on image noise and processing time.

OBJECTIVES: To assess the effect of standard filtered back projection (FBP) and iterative reconstruction (IR) methods on CBCT image noise and processing time (PT), acquired with various acquisition parameters with and without metal artefact reduction (MAR). METHODS: CBCT scans using the Midmark EIOS unit of a human mandible embedded in soft tissue equivalent material with and without the presence of an implant at mandibular first molar region were acquired at various acquisition settings (milliamperages [4mA-14mA], FOV [5 × 5, 6 × 8, 9 × 10 cm], and resolutions [low, standard, high] and reconstructed using standard FBP and IR, and with and without MAR. The processing time was recorded for each reconstruction. ImageJ was used to analyze specific axial images. Radial transaxial fiducial lines were created relative to the implant site. Standard deviations of the gray density values (image noise) were calculated at fixed distances on the fiducial lines on the buccal and lingual aspects at specific axial levels, and mean values for FBP and IR were compared using paired t-tests. Significance was defined as p < 0.05. RESULTS: The overall mean for image noise (± SD) for FBP was 198.65 ± 55.58 and 99.84 ± 16.28 for IR. IR significantly decreased image noise compared to FBP at all acquisition parameters (p < 0.05). Noise reduction among different scanning protocols ranged between 29.7% (5 × 5 cm FOV) and 58.1% (5mA). IR increased processing time by an average of 35.1 s. CONCLUSIONS: IR significantly reduces CBCT image noise compared to standard FBP without substantially increasing processing time.

Activity of the osmotically regulated yqiHIK promoter from Bacillus subtilis is controlled at a distance.

The yqiHIK gene cluster from Bacillus subtilis is predicted to encode an extracellular lipoprotein (YqiH), a secreted N-acetylmuramoyl-L-alanine amidase (YqiI), and a cytoplasmic glycerophosphodiester phosphodiesterase (YqiK). Reverse transcriptase PCR (RT-PCR) analysis showed that the yqiHIK genes are transcribed as an operon. Consistent with the in silico prediction, we found that the purified YqiI protein exhibited hydrolytic activity toward peptidoglycan sacculi. Transcription studies with yqiH-treA reporter fusion strains revealed that the expression of yqiHIK is subjected to finely tuned osmotic control, but enhanced expression occurs only in severely osmotically stressed cells. Primer extension analysis pinpointed the osmotically responsive yqiHIK promoter, and site-directed mutagenesis was employed to assess functionally important sequences required for promoter activity and osmotic control. Promoter variants with constitutive activity were isolated. A deletion analysis of the yqiHIK regulatory region showed that a 53-bp AT-rich DNA segment positioned 180 bp upstream of the -35 sequence is critical for the activity and osmotic regulation of the yqiHIK promoter. Hence, the expression of yqiHIK is subjected to genetic control at a distance. Upon the onset of growth of cells of the B. subtilis wild-type strain in high-salinity medium (1.2 M NaCl), we observed gross morphological deformations of cells that were then reversed to a rod-shaped morphology again when the cells had adjusted to the high-salinity environment. The products of the yqiHIK gene cluster were not critical for reestablishing rod-shaped morphology, but the deletion of this operon yielded a B. subtilis mutant impaired in growth in a defined minimal medium and at high salinity.

The structure of the extracellular teichoic acids from the allergy-protective bacterium Lactococcus lactis G121.

The Gram-positive bacterium Lactococcus lactis G121 is a farm isolate that protects mice from ovalbumin-induced asthma. To understand the molecular mechanisms of such allergy-protective properties, the isolation and characterization of cell envelope constituents is crucial. Here, structural analyses of the extracellular teichoic acid (EC TA) from L. lactis G121 are presented. Extraction with 0.9% saline afforded a crude TA fraction. Consecutive size exclusion chromatography on Biogel P60 and P10 matrix was performed to purify the sample. Chemical component analyses, high-resolution electrospray ionization Fourier-transformed ion cyclotron mass spectrometry, and nuclear magnetic resonance spectroscopy were conducted for structural elucidation. The EC TA was a poly(glycosylglycerol phosphate) molecule with a repeating unit of -6)-[ß-D-Glcp-(1→3)-][α-D-GlcpNAc-(1→4)-]α-D-GalpNAc-(1→3)-ß-D-GlcpNAc-(1→2)-glycerol-(1-P-).