High-resolution computational imaging of leaf hair patterning using polarized light microscopy.

The leaf hairs (trichomes) on the aerial surface of many plant species play important roles in phytochemical production and herbivore protection, and have significant applications in the chemical and agricultural industries. Trichome formation in the model plant Arabidopsis thaliana also presents a tractable experimental system to study cell differentiation and pattern formation in plants and animals. Studies of this developmental process suggest that trichome positioning may be the result of a self-forming pattern, emerging from a lateral inhibition mechanism determined by a network of regulatory factors.

From plant gene regulatory grids to network dynamics.

The regulation of gene expression is the most basic level at which genotypes encoded in DNA can manifest themselves into observable phenotypes. In eukaryotes, gene regulatory networks (GRNs) describe the regulatory web through which transcription factors and microRNAs tightly regulate the spatial and temporal expression of genes. In yeast, Escherichia coli, and animals the study of GRNs has uncovered many of the network properties responsible for creating complex regulatory behavior such as organism growth, development, and response to environmental stimuli.

Putative molecular mechanisms underlying tandem CCCH zinc finger protein mediated plant growth, stress, and gene expression responses.

In animals, Tandem CCCH Zinc Finger (TZF) proteins control a variety of cellular processes via regulation of gene expression at transcriptional and post-transcriptional levels. Plant-unique TZF proteins can also affect many aspects of plant growth, development, and stress responses. However, the molecular mechanisms underlying plant TZF function are unknown.

Can AtTZF1 act as a transcriptional activator or repressor in plants?

In animals, Tandem CCCH Zinc Finger (TZF) proteins can affect gene expression at both transcriptional and post-transcriptional levels. In Arabidopsis thaliana, AtTZF1 is a member of the TZF family characterized by a plant-unique tandem zinc finger motif. AtTZF1 can bind both DNA and RNA in vitro, and it can traffic between the nucleus and cytoplasmic foci.

The Arabidopsis tandem zinc finger protein AtTZF1 affects ABA- and GA-mediated growth, stress and gene expression responses.

Tandem zinc finger (TZF) proteins are characterized by two zinc-binding CCCH motifs arranged in tandem. Human TZFs such as tristetraproline (TTP) bind to and trigger the degradation of mRNAs encoding cytokines and various regulators. Although the molecular functions of plant TZFs are unknown, recent genetic studies have revealed roles in hormone-mediated growth and environmental responses, as well as in the regulation of gene expression.

AtTZF gene family localizes to cytoplasmic foci.

In eukaryotes, mRNA turnover and translational repression represent important regulatory steps in gene expression. Curiously, when under cellular stresses, factors involved in these processes aggregate into cytoplasmic foci known as Processing bodies (P-bodies) and Stress Granules (SGs). In animals, CCCH Tandem Zinc Finger (TZF) proteins play important roles in mRNA decay within P-bodies.

The Arabidopsis tandem zinc finger protein AtTZF1 traffics between the nucleus and cytoplasmic foci and binds both DNA and RNA.

Processing bodies (PBs) are specialized cytoplasmic foci where mRNA turnover and translational repression can take place. Stress granules are related cytoplasmic foci. The CCCH tandem zinc finger proteins (TZFs) play pivotal roles in gene expression, cell fate specification, and various developmental processes.