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Root Regions (root + regions)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Effect of post-space treatment on retention of fiber posts in different root regions using two self-etching systems

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2008
Ling Zhang
The effect of post-space treatment on the retention of fiber posts in different root regions was evaluated using two self-etching systems. Post spaces were prepared in extracted premolars and then the root canals were subjected to one of the following post-space treatments: (i) water irrigation (control); (ii) etching with 35% phosphoric acid for 30 s; (iii) irrigation with 17% EDTA followed by 5.25% sodium hypochlorite (NaOCl); and (iv) ultrasonic agitation associated with 17% EDTA and 5.25% NaOCl irrigating solutions. The dentin surfaces were examined under scanning electron microscopy (SEM) after different post-space treatments. Fiber posts were then luted in the treated roots using resin cement with either Clearfil SE Bond or Clearfil DC Bond, and the thin-slice push-out test was performed. Scanning electron microscopy showed that all the post-space treatments tested were effective in removal of the smear layer of debris, or sealer/gutta-percha remnants, on the root canal. The apical push-out strength was affected by post-space treatment. Both 35% phosphoric acid etching and ultrasonic agitation in combination with EDTA/NaOCl irrigation improved the apical push-out strength of the fiber post, regardless of the type of self-etching system. A solo irrigation with an EDTA/NaOCl solution resulted in a lower apical push-out strength compared with the other two experimental groups. [source]

Analysing scots pine defence-related transcripts and fungal DNA levels in seedlings single- or dual-inoculated with endophytic and pathogenic Rhizoctonia species

FOREST PATHOLOGY, Issue 6 2009
H. Grönberg
Summary Fungal DNA and induction of host defence-related transcripts were monitored by real-time PCR in young Scots pine seedlings inoculated with pathogenic uninucleate (UNR) and endophytic binucleate (BNR) Rhizoctonia species. The UNR (teleomorph Ceratobasidium bicorne) causes root dieback in conifer seedlings following invasion of the vascular cylinder via root apex and destroying apical meristems whilst the BNR, representing anastomosis group AG-I of genus Ceratobasidium, is primarily restricted to the cortex in basal root regions. In the experiment 1 the fungi were simultaneously inoculated on roots, while in experiment 2, BNR was pre-inoculated 168 h before inoculation with UNR. Nucleic acids were extracted from infected roots at intervals up to 192 h post-infection (hpi), and the genomic DNA levels of the host and fungi and the transcript levels of a house-keeping gene (glyceraldehyde-3-phosphate dehydrogenase) and nine putative defence genes were quantified. In simultaneous inoculation UNR was more competitive than BNR whereas pre-inoculation of BNR suppressed but did not completely prevent root colonization by UNR. Stilbene synthase (STS) transcription was significantly up-regulated in single-inoculations with both fungi and in dual inoculation in both experiments. Maximum STS transcript levels were observed in roots single-inoculated with UNR; the peak level at 48 hpi in experiment 2 was significantly higher than in seedlings single-inoculated with BNR or co-inoculated with both fungi, the latter two treatments showing relatively similar STS transcript levels. Similarly, transcript levels of phenylalanine ammonia lyase at 48 hpi in experiment 2 were significantly higher in roots single-inoculated with UNR compared with BNR or in UNR+BNR co-inoculations. The other seven putative defence genes monitored did not show any clear-cut up-regulation following fungal inoculation. We conclude that BNR suppresses UNR in Scots pine roots via direct competition for infection sites, since the studied transcripts showed no evidence of BNR induced resistance against UNR. [source]

Functional ecology of a blue light photoreceptor: effects of phototropin-1 on root growth enhance drought tolerance in Arabidopsis thaliana

NEW PHYTOLOGIST, Issue 1 2007
Candace Galen
Summary ,,The blue light photoreceptor phototropin-1 has been shown to enhance fitness in Arabidosis thaliana under field conditions. Here, we ask whether performance consequences of phototropin-1 reflect its impact on root growth and drought tolerance. ,,We used a PHOT1-GFP gene construct to test whether phototropin-1 abundance in roots is highest at shallow soil depths where light penetration is greatest. We then compared root growth efficiency and size at maturity between individuals with and without functional phototropin-1. Comparisons were made under wet and dry conditions to assess the impact of phototropin-1 on drought tolerance. ,,Phototropin-1 was most abundant in upper root regions and its impact on root growth efficiency decreased with soil depth. Roots of plants with functional phototropin-1 made fewer random turns and traveled further for a given length (higher efficiency) than roots of phot1 mutants. In dry (but not wet) soil, enhancement of root growth efficiency by phototropin-1 increased plant size at maturity. ,,Results indicate that phototropin-1 enhances performance under drought by mediating plastic increases in root growth efficiency near the soil surface. [source]