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Full-Text Articles in Cell Biology

Münch, Morphology, Microfluidics – Our Structural Problem With The Phloem [Review Article], Michael Knoblauch, Winfried S. Peters Aug 2010

Münch, Morphology, Microfluidics – Our Structural Problem With The Phloem [Review Article], Michael Knoblauch, Winfried S. Peters

Winfried S. Peters

The sieve tubes of the phloem are enigmatic structures. Their role as channels for the distribution of assimilates was established in the 19th century, but their sensitivity to disturbations has hampered the elucidation of their transport mechanisms and its regulation ever since. Ernst Münch's classical monograph of 1930 is generally regarded as the first coherent theory of phloem transport, but the ‘Münchian’ pressure flow mechanism had been discussed already before the turn of the century. Münch's impact rather rested on his simple physical models of the phloem that visualized pressure flow in an intuitive way, and we argue ...


Legume Phylogeny And The Evolution Of A Unique Contractile Apparatus That Regulates Phloem Transport, Winfried Peters, Claudia Hanakam, Dietmar Haffer, Aart Van Bel, Michael Knoblauch Mar 2010

Legume Phylogeny And The Evolution Of A Unique Contractile Apparatus That Regulates Phloem Transport, Winfried Peters, Claudia Hanakam, Dietmar Haffer, Aart Van Bel, Michael Knoblauch

Winfried S. Peters

Protein bodies called forisomes undergo Ca2+-dependent deformations to occlude sieve tubes reversibly, providing a unique regulatory mechanism of phloem transport. Because forisomes are known exclusively from the Papilionoideae (Leguminosae), the evolution of forisome function may have played a role in the rapid radiation of this huge taxon. The unexpected discovery of a papilionoid species lacking forisomes led us to evaluate a representative set of species covering 33 of the 36 legume tribes traditionally recognized. We found forisomes in Papilionoideae but not in Caesalpinioideae and Mimosoideae. Forisomes were absent from several species of the papilionoid tribe Galegeae. Forisomes with tail-like ...


The Wheat Bzip Factor, Taabf1, Mediates Aba-Induced Gene Expression In Bombarded Barley Aleurone Layers, Benjamin R. Keyser Jan 2010

The Wheat Bzip Factor, Taabf1, Mediates Aba-Induced Gene Expression In Bombarded Barley Aleurone Layers, Benjamin R. Keyser

Honors Theses

The plant hormone Abscisic acid (ABA) plays a central role in maturation and germination in seeds, as well as mediating adaptive responses to abiotic environmental stresses. ABA induces the expression of many genes, including late-embryogenesis-abundant genes such as HVA1. To elucidate the ABA signaling pathway leading to HVA1 expression, we focus on the bZIP factor TaABF1. Analysis of the interplay between ABA and TaABF1 in the aleurone cells of imbibing cereal grains indicated that the two are not additive in their induction of the HVA1 promoter. A synthetic ABA analog, PBI-51, did not specifically inhibit the effect of exogenous ABA ...


Tor Is A Negative Regulator Of Autophagy In Arabidopsis Thaliana, Yimo Liu, Diane C. Bassham Jan 2010

Tor Is A Negative Regulator Of Autophagy In Arabidopsis Thaliana, Yimo Liu, Diane C. Bassham

Genetics, Development and Cell Biology Publications

Background: Autophagy is a protein degradation process by which cells recycle cytoplasmic contents under stress conditions or during senescence; a basal level of housekeeping autophagy also occurs under non-stressed conditions. Although a number of genes that function in autophagy (ATG genes) have been identified in plants, the upstream components that regulate the plant autophagy pathway are still obscure. Target of rapamycin (TOR) is a negative regulator of autophagy in both yeast and animals, and homologs of TOR in plants control plant growth and protein synthesis. However, a role for TOR in regulation of autophagy in plants has not been demonstrated ...