A Dual-Promoter Gene Orchestrates the Sucrose-Coordinated Synthesis of Starch and Fructan in Barley.

Sequential carbohydrate synthesis is important for plant survival because it guarantees energy supplies for growth and development during plant ontogeny and reproduction. Starch and fructan are two important carbohydrates in many flowering plants and in human diets. Understanding this coordinated starch and fructan synthesis and unraveling how plants allocate photosynthates and prioritize different carbohydrate synthesis for survival could lead to improvements to cereals in agriculture for the purposes of greater food security and production quality. Here, we report a system from a single gene in barley employing two alternative promoters, one intronic/exonic, to generate two sequence-overlapping but functionally opposing transcription factors, in sensing sucrose, potentially via sucrose/glucose/fructose/trehalose 6-phosphate signaling. The system employs an autoregulatory mechanism in perceiving a sucrose-controlled trans activity on one promoter and orchestrating the coordinated starch and fructan synthesis by competitive transcription factor binding on the other promoter. As a case in point for the physiological roles of the system, we have demonstrated that this multitasking system can be exploited in breeding barley with tailored amounts of fructan to produce healthy food ingredients. The identification of an intron/exon-spanning promoter in a hosting gene, resulting in proteins with distinct functions, adds to the complexity of plant genomes.

Rinsing with alcohol-free or alcohol-based chlorhexidine solutions after periodontal surgery. A double-blind, randomized, cross-over, pilot study.

The aim of this randomized, double-blind, cross-over pilot study was to evaluate the effect on plaque formation and patient experience of rinsing after periodontal surgery using chlorhexidine solution with or without alcohol. Twenty patients refrained from tooth brushing after surgery and used two mouth rinses.Ten patients used alcohol-based (AB) 0.1% and another ten used alcohol-free (AF) 0.12% chlorhexidine (CHX). Sutures were removed after 2 weeks and teeth were cleaned; thereafter, the two groups shifted solution. Plaque at operated teeth was recorded at 2 and 4 weeks (Quigley-Hein Index). Patient experience was assessed with a visual analogue scale (0-10). Mean (SD) plaque indices at 2 and 4 weeks were 1.0 (0.8) and 1.1 (1.0) for AB CHX and 1.1 (0.7) and 0.8 (0.7) for AF CHX, respectively (no significant differences between solutions). At 2 weeks, between-group differences in taste experience of the solutions differed non-significantly: 6.1 (2.8) for AB and 6.0 (2.3) for AF. At 4 weeks, values were 4.6 (2.5) for AB and 6.9 (3.3) for AF-patients tended to prefer AF (p = 0.050). Taste change over the study period was equal for both groups: -37 (3.3) for AB and 3.4 (2.3) for AF at 2 weeks and slightly higher at 4 weeks 4.9 (2.8) and 4.5 (2.5) for AB and AF, respectively. Smarting was low in both groups: 2.2 (3.2) and 1.3 (2.2) for AB and 1.0 (1.5) and 1.9 (2.0) for AF at 2 and 4 weeks, respectively. To conclude, alcohol-free and alcohol-based chlorhexidine showed the same plaque inhibitory effect in periodontal patients after periodontal surgery. Both rinses were well tolerated by the patients.

Sugar-mediated semidian oscillation of gene expression in the cassava storage root regulates starch synthesis.

Starch branching enzyme (SBE) activity in the cassava storage root exhibited a diurnal fluctuation, dictated by a transcriptional oscillation of the corresponding SBE genes. The peak of SBE activity coincided with the onset of sucrose accumulation in the storage, and we conclude that the oscillatory mechanism keeps the starch synthetic apparatus in the storage root sink in tune with the flux of sucrose from the photosynthetic source. When storage roots were uncoupled from the source, SBE expression could be effectively induced by exogenous sucrose. Turanose, a sucrose isomer that cannot be metabolized by plants, mimicked the effect of sucrose, demonstrating that downstream metabolism of sucrose was not necessary for signal transmission. Also glucose and glucose-1-P induced SBE expression. Interestingly, induction by sucrose, turanose and glucose but not glucose-1-P sustained an overt semidian (12-h) oscillation in SBE expression and was sensitive to the hexokinase (HXK) inhibitor glucosamine. These results suggest a pivotal regulatory role for HXK during starch synthesis. Abscisic acid (ABA) was another potent inducer of SBE expression. Induction by ABA was similar to that of glucose-1-P in that it bypassed the semidian oscillator. Both the sugar and ABA signaling cascades were disrupted by okadaic acid, a protein phosphatase inhibitor. Based on these findings, we propose a model for sugar signaling in regulation of starch synthesis in the cassava storage root.

Antisense oligodeoxynucleotide inhibition as a potent strategy in plant biology: identification of SUSIBA2 as a transcriptional activator in plant sugar signalling.

Sugar signalling cascades are important components of regulatory networks in cells. Compared with the situation in bacteria, yeast and animals, participants of the sugar signalling pathways in plants are poorly understood. Several genes involved in starch synthesis are known to be sugar inducible, although the signal transduction pathways remain undisclosed. We reported recently the isolation of SUSIBA2, a transcription factor involved in sugar-mediated regulation of starch synthesis. Here, we used antisense oligodeoxynucleotide (ODN) inhibition, a powerful approach in medical sciences, to block the effects of SUSIBA2 in sugar-treated barley leaves. The uptake and intracellular trafficking of an 18-mer susiba2 antisense ODN in leaves were followed by confocal microscopy. Administration of the antisense ODN to the leaves impeded susiba2 expression by RNase H activation. This dramatically diminished the ectopic expression of the iso1 and sbeIIb genes and resulted in altered starch synthesis. This study illustrates the successful exploitation of the antisense ODN technology in plant biology, e.g. as a rapid antecedent to time-consuming transgenic studies, and identifies SUSIBA2 as a transcriptional activator in plant sugar signalling. Based on our findings, we propose a model for sugar-signalling control of starch synthesis.

A novel WRKY transcription factor, SUSIBA2, participates in sugar signaling in barley by binding to the sugar-responsive elements of the iso1 promoter.

SURE (sugar responsive) is a cis element in plant sugar signaling. The SURE element was reported first for potato, in which it confers sugar responsiveness to the patatin promoter. A SURE binding transcription factor has not been isolated. We have isolated a transcription factor cDNA from barley and purified the corresponding protein. The transcription factor, SUSIBA2 (sugar signaling in barley), belongs to the WRKY proteins and was shown to bind to SURE and W-box elements but not to the SP8a element in the iso1 promoter. Nuclear localization of SUSIBA2 was demonstrated in a transient assay system with a SUSIBA2:green fluorescent protein fusion protein. Exploiting the novel transcription factor oligodeoxynucleotide decoy strategy with transformed barley endosperm provided experimental evidence for the importance of the SURE elements in iso1 transcription. Antibodies against SUSIBA2 were produced, and the expression pattern for susiba2 was determined at the RNA and protein levels. It was found that susiba2 is expressed in endosperm but not in leaves. Transcription of susiba2 is sugar inducible, and ectopic susiba2 expression was obtained in sugar-treated leaves. Likewise, binding to SURE elements was observed for nuclear extracts from sugar-treated but not from control barley leaves. The temporal expression of susiba2 in barley endosperm followed that of iso1 and endogenous sucrose levels, with a peak at approximately 12 days after pollination. Our data indicate that SUSIBA2 binds to the SURE elements in the barley iso1 promoter as an activator. Furthermore, they show that SUSIBA2 is a regulatory transcription factor in starch synthesis and demonstrate the involvement of a WRKY protein in carbohydrate anabolism. Orthologs to SUSIBA2 were isolated from rice and wheat endosperm.

Undergraduate education in endodontology at two European dental schools. A comparison between the Faculty of Odontology, Malmö University, Malmö, Sweden and Faculty of Odontology, Paris 5 University (René Descartes), France.

The aim of this study was to compare the courses in endodontics and to assess the treatment quality in the student clinics in two dental schools, in Malmö, Sweden and Paris, France. A further aim was to improve the curriculum development in Paris 5 and Malmö by testing student exchange programmes. The comparison was based on the guidelines for undergraduate education set up by the European Society of Endodontology (ESE) [Int. Endod. J. 25 (1992) 169] and on the criteria formulated by Qualtrough and Dummer [Int. Endod. J. 30 (1997) 234]. The latter criteria covered the following aspects: educational methods, the timing of endodontic teaching, pre-clinical practical exercises, student assessment, recommended literature, clinical/practical procedures, the education of the staff and number of students per teacher. The quality guidelines for endodontic treatment set up by the ESE [Int. Endod. J. 27 (1994) 115] were used for the assessment of the quality of the treatment. The following aspects were covered: history, diagnosis and treatment planning, records, infection control, root-canal treatment, assessment of endodontic treatment. The undergraduate education in endodontics was fundamentally similar in Paris 5 and Malmö. The main differences observed were related to: Educational methods: In Malmö, problem-based learning and in Paris 5, traditional. Assessment of student performance. In Malmö, self-assessment and in Paris 5, credits for clinical/practical procedures. Clinical/practical procedures relating to infection control. Aseptic treatment regimens were more meticulously performed in Malmö than in Paris 5. Assessment (follow-up) of all endodontic treatments was a routine only in Malmö.