Influence of DNA conformation and role ofcomAandrecAon natural transformation inRalstonia solanacearum

2009 ◽  
Vol 55 (6) ◽  
pp. 762-770 ◽  
Author(s):  
Anne Mercier ◽  
Franck Bertolla ◽  
Eugénie Passelègue-Robe ◽  
Pascal Simonet

Naturally competent bacteria such as the plant pathogen Ralstonia solanacearum are characterized by their ability to take up free DNA from their surroundings. In this study, we investigated the efficiency of various DNA types including chromosomal linear DNA and circular or linearized integrative and (or) replicative plasmids to naturally transform R. solanacearum. To study the respective regulatory role of DNA transport and maintenance in the definite acquisition of new DNA by bacteria, the natural transformation frequencies were compared with those obtained when the bacterial strain was transformed by electroporation. An additional round of electrotransformation and natural transformation was carried out with the same set of donor DNAs and with R. solanacearum disrupted mutants that were potentially affected in competence (comA gene) and recombination (recA gene) functions. Our results confirmed the critical role of the comA gene for natural transformation and that of recA for recombination and, more surprisingly, for the maintenance of an autonomous plasmid in the host cell. Finally, our results showed that homologous recombination of chromosomal linear DNA fragments taken up by natural transformation was the most efficient way for R. solanacearum to acquire new DNA, in agreement with previous data showing competence development and natural transformation between R. solanacearum cells in plant tissues.

Author(s):  
Janet H. Woodward ◽  
D. E. Akin

Silicon (Si) is distributed throughout plant tissues, but its role in forages has not been clarified. Although Si has been suggested as an antiquality factor which limits the digestibility of structural carbohydrates, other research indicates that its presence in plants does not affect digestibility. We employed x-ray microanalysis to evaluate Si as an antiquality factor at specific sites of two cultivars of bermuda grass (Cynodon dactvlon (L.) Pers.). “Coastal” and “Tifton-78” were chosen for this study because previous work in our lab has shown that, although these two grasses are similar ultrastructurally, they differ in in vitro dry matter digestibility and in percent composition of Si.Two millimeter leaf sections of Tifton-7 8 (Tift-7 8) and Coastal (CBG) were incubated for 72 hr in 2.5% (w/v) cellulase in 0.05 M sodium acetate buffer, pH 5.0. For controls, sections were incubated in the sodium acetate buffer or were not treated.


2008 ◽  
Vol 15 (2) ◽  
pp. 50-59 ◽  
Author(s):  
Amy Philofsky

AbstractRecent prevalence estimates for autism have been alarming as a function of the notable increase. Speech-language pathologists play a critical role in screening, assessment and intervention for children with autism. This article reviews signs that may be indicative of autism at different stages of language development, and discusses the importance of several psychometric properties—sensitivity and specificity—in utilizing screening measures for children with autism. Critical components of assessment for children with autism are reviewed. This article concludes with examples of intervention targets for children with ASD at various levels of language development.


1998 ◽  
Vol 5 (1) ◽  
pp. 115A-115A
Author(s):  
K CHWALISZ ◽  
E WINTERHAGER ◽  
T THIENEL ◽  
R GARFIELD
Keyword(s):  

2018 ◽  
Vol 20 (3) ◽  
pp. 99-110
Author(s):  
Na Zhang ◽  
Jingjing Li ◽  
Xing Bu ◽  
Zhenxing Gong ◽  
Gilal Faheem Gul

2016 ◽  
Vol 10 (2) ◽  
pp. 1 ◽  
Author(s):  
Melody Hermel ◽  
Rebecca Duffy ◽  
Alexander Orfanos ◽  
Isabelle Hack ◽  
Shayna McEnteggart ◽  
...  

Cardiac registries have filled many gaps in knowledge related to arrhythmogenic cardiovascular conditions. Despite the less robust level of evidence available in registries when compared with clinical trials, registries have contributed a range of clinically useful information. In this review, the authors discuss the role that registries have played – related to diagnosis, natural history, risk stratification, treatment, and genetics of arrhythmogenic cardiovascular conditions – in closing knowledge gaps, and their role in the future.


2018 ◽  
Vol 2018 ◽  
pp. 1004-1014
Author(s):  
Sofia Batsila ◽  
◽  
George Panigyrakis ◽  
Anastasios Panopoulos

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