Linked Life Data

9421933

Source:http://linkedlifedata.com/resource/pubmed/id/9421933

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1998-3-17
pubmed:abstractText
Tip growth of plant cells has been suggested to be regulated by a tip-focused gradient in cytosolic calcium concentration ([Ca2+]c). However, whether this gradient orients apical growth or follows the driving force for this process remains unknown. Using localized photoactivation of the caged calcium ionophore Br-A23187 we have been able to artificially generate an asymmetrical calcium influx across the root hair tip. This led to a change in the direction of tip growth towards the high point of the new [Ca2+]c gradient. Such reorientation of growth was transient and there was a return to the original direction within 15 min. Root hairs forced to change the direction of their growth by placing a mechanical obstacle in their path stopped, reoriented growth to the side, and grew past the mechanical blockage. However, as soon as the growing tip had cleared the obstacle, growth returned to the original direction. Confocal ratio imaging revealed that a tip-focused [Ca2+]c gradient was always centered at the site of active growth. When the root hair changed direction the gradient also reoriented, and when growth returned to the original direction, so did the [Ca2+]c gradient. This normal direction of apical growth of Arabidopsis thaliana (L.) Heynh, root hairs was found to be at a fixed angle from the root of 85 +/- 6.7 degrees. In contrast, Tradescantia virginiana (L.) pollen tubes that were induced to reorient by touch or localized activation of the caged ionophore, did not return to the original growth direction, but continued to elongate in their new orientation. These results suggest that the tip-focused [Ca2+]c gradient is an important factor in localizing growth of the elongating root hair and pollen tube to the apex. However, it is not the primary determinant of the direction of elongation in root hairs, suggesting that other information from the root is acting to continuously reset the growth direction away from the root surface.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
B
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0032-0935
pubmed:author
pubmed:issnType
Print
pubmed:volume
203
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
495-505
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Root hair growth in Arabidopsis thaliana is directed by calcium and an endogenous polarity.
pubmed:affiliation
Department of Biology, Pennsylvania State University, University Park 16802, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S.