Indole acetic acid production by fluorescent Pseudomonas spp. from the rhizosphere of Plectranthus amboinicus (Lour.) Spreng. and their variation in extragenic repetitive DNA sequences.

Fluorescent Pseudomonas (FP) is a heterogenous group of growth promoting rhizobacteria that regulate plant growth by releasing secondary metabolic compounds viz., indole acetic acid (IAA), siderophores, ammonia and hydrogen cyanide. In the present study, IAA producing FPs from the rhizosphere of Plectranthus amboinicus were characterized morphologically, biochemically and at the molecular level. Molecular identification of the isolates were carried out using Pseudomonas specific primers. The effect of varying time (24, 48, 72 and 96 h), Trp concentrations (100, 200, 300, 400 and 500 µg.ml-1), temperature (10, 26, 37 and 50±2 °C) and pH (6, 7 and 8) on IAA production by 10 best isolates were studied. Results showed higher IAA production at 72 h incubation, at 300 µg.ml-1 Trp concentration, temperature 26±2 °C and pH 7. TLC with acidified ethyl acetate extract showed that the IAA produced has a similar Rf value to that of the standard IAA. Results of TLC were confirmed by HPLC analysis. Genetic diversity of the isolates was also studied using 40 RAPD and 4 Rep primers. Genetic diversity parameters such as dominance, Shannon index and Simpson index were calculated. Out of 40 RAPD primers tested, 9 (2 OP-D series and 7 OP-E series) were shortlisted for further analysis. Studies using RAPD, ERIC, BOX, REP and GTG5 primers revealed that isolates exhibit significant diversity in repetitive DNA sequences irrespective of the rhizosphere.

Perception of Smile Attractiveness by Laypeople–influence of Profession and Treatment Experience.

Aims: To assess the influence of profession, treatment experience, age and gender on the perception of smile aesthetics with different buccal corridors and smile arcs, and to identify the threshold where buccal corridor space becomes aesthetically displeasing. Study Design: A questionnaire-based descriptive study on the assessment of attractiveness ratings by laypeople. Place and Duration of Study: Amman/Jordan, University of Jordan Hospital; Faculty of Dentistry, Division of Orthodontics, from 2010-2011. Methodology: A coloured photograph of a female smile was digitally modified to produce six smile images with buccal corridor spaces (BCSs) ranging from 0% to 25% and three smile images with altered smile arcs (consonant, flat and reverse). These images were shown to 104 laypeople who were asked to rate the attractiveness of each smile on a scale of one to ten. Analysis of variance was used to study the effect of age, gender, profession and treatment experience on smile attractiveness rating. A one-way ANOVA post hoc Duncan test was used to establish the threshold where BCS was considered unattractive. Results: The most attractive smile was the broadest and consonant smile (7.42 +/- 1.87). The image with a reverse smile arc was rated as the least attractive (2.65 +/- 1.85). Duncan’s test revealed that the threshold at which BCS was considered significantly unattractive was when it reached 25%. Analysis of variance showed that young adults perceived the broadest smile as significantly more attractive than older adults (P = .03). Profession had a significant influence on smile attractiveness ratings while gender and treatment experience did not. Conclusion: Flattening the smile arc was found to have more of an unattractive bearing than small variations in BCS. Thus, it is advisable to take into consideration the smile arc during any treatment that involves the anterior maxillary area, especially prosthodontic and restorative treatments, orthognathic surgery and orthodontics.