Hormonal regulation of a cysteine proteinase gene, EPB-1, in barley aleurone layers: cis- and trans-acting elements involved in the co-ordinated gene expression regulated by gibberellins and abscisic acid.

The synthesis of EPB, a cysteine proteinase responsible for the degradation of seed endosperm storage proteins in barley (Hordeum vulgare), is induced by gibberellins (GA) and repressed by abscisic acid (ABA). The EPB gene family consists of two very similar members, EPB-1 and EPB-2, with the former being more highly induced by GA. We have functionally characterized the cis-acting elements in the EPB-1 promoter and determined that a gibberellin response element (GARE), a pyrimidine box and an upstream element are necessary for GA induction. By comparison with the promoters of alpha-amylase genes, which are also induced by GA, we suggest that GARE is coupled with the upstream element and the pyrimidine box to form a GA response complex. In addition, we have shown that the 3'-untranslated/untranscribed region of the EPB-1 gene is required for a low background expression in the absence of GA. Constitutive expression of a transcription factor, GAMyb, in the absence of GA leads to the transactivation of EPB-1 expression in a dosage dependent manner with the highest level comparable to that in fully GA-induced tissue. Co-expression of a truncated version of GAMyb containing only the DNA binding domain blocks the GA-induction of EPB-1, further supporting the role of GAMyb in the regulation of gene expression. Although ABA is very effective in blocking the GA induction of EPB-1, it has no effect on the GAMyb-mediated expression of EPB-1. We suggest that ABA acts upstream of the formation of functional GAMyb which co-ordinates the hormonal regulation of a diverse group of genes in cereal aleurone layers, including those encoding EPB and alpha-amylases.

Experience-Weighted Attraction Learning in Coordination Games: Probability Rules, Heterogeneity, and Time-Variation.

In earlier research we proposed an "experience-weighted attraction (EWA) learning" model for predicting dynamic behavior in economic experiments on multiperson noncooperative normal-form games. We showed that EWA learning model fits significantly better than existing learning models (choice reinforcement and belief-based models) in several different classes of games. The econometric estimation in that research adopted a representative agent approach and assumed that learning parameters are stationary across periods of an experiment. In addition, we used the logit (exponential) probability response function to transform attraction of strategies into choice probability. This paper allows for nonstationary learning parameters, permits two "segments" of players with different parameter values in order to allow for some heterogeneity, and compares the power and logit probability response functions. These specifications are estimated using experimental data from weak-link and median-action coordination games. Results show that players are heterogeneous and that they adjust their learning parameters over time very slightly. Logit probability response functions never fit worse than power functions, and generally fit better. Copyright 1998 Academic Press.

Dehydration-stress-regulated transgene expression in stably transformed rice plants

To confer abscisic acid (ABA) and/or stress-inducible gene expression, an ABA-response complex (ABRC1) from the barley (Hordeum vulgare L.) HVA22 gene was fused to four different lengths of the 5' region from the rice (Oryza sativa L.) Act1 gene. Transient assay of beta-glucuronidase (GUS) activity in barley aleurone cells shows that, coupled with ABRC1, the shortest minimal promoter (Act1-100P) gives both the greatest induction and the highest level of absolute activity following ABA treatment. Two plasmids with one or four copies of ABRC1 combined with the same Act1-100P and HVA22(I) of barley HVA22 were constructed and used for stable expression of uidA in transgenic rice plants. Three Southern blot-positive lines with the correct hybridization pattern for each construct were obtained. Northern analysis indicated that uidA expression is induced by ABA, water-deficit, and NaCl treatments. GUS activity assays in the transgenic plants confirmed that the induction of GUS activity varies from 3- to 8-fold with different treatments or in different rice tissues, and that transgenic rice plants harboring four copies of ABRC1 show 50% to 200% higher absolute GUS activity both before and after treatments than those with one copy of ABRC1.