ATHB12, an ABA-inducible homeodomain-leucine zipper (HD-Zip) protein of Arabidopsis, negatively regulates the growth of the inflorescence stem by decreasing the expression of a gibberellin 20-oxidase gene.

Arabidopsis thaliana homeobox 12 (ATHB12) is rapidly induced by ABA and water stress. A T-DNA insertion mutant of ATHB12 with a reduced level of ATHB12 expression in stems had longer inflorescence stems and reduced sensitivity to ABA during germination. A high level of transcripts of gibberellin 20-oxidase 1 (GA20ox1), a key enzyme in the synthesis of gibberellins, was detected in athb12 stems, while transgenic lines overexpressing ATHB12 (A12OX) had a reduced level of GA20ox1 in stems. Consistent with these data, ABA treatment of wild-type plants resulted in decreased GA20ox1 expression whereas ABA treatment of the athb12 mutant gave rise to slightly decreased GA20ox1 expression. Retarded stem growth in 3-week-old A12OX plants was rescued by exogenous GA(9), but not by GA(12), and less GA(9) was detected in A12OX stems than in wild-type stems. These data imply that ATHB12 decreases GA20ox1 expression in stems. On the other hand, the stems of A12OX plants grew rapidly after the first 3 weeks, so that they were almost as high as wild-type plants at about 5 weeks after germination. We also found changes in the stems of transgenic plants overexpressing ATHB12, such as alterations of expression GA20ox and GA3ox genes, and of GA(4) levels, which appear to result from feedback regulation. Repression of GA20ox1 by ATHB12 was confirmed by transfection of leaf protoplasts. ABA-treated protoplasts also showed increased ATHB12 expression and reduced GA20ox1 expression. These findings all suggest that ATHB12 negatively regulates the expression of a GA 20-oxidase gene in inflorescence stems.

Impact of depressive mood on lifestyle changes in patients with coronary artery disease.

OBJECTIVE: The aims of this study were to investigate the time-course of depressive mood in patients with coronary artery disease during a secondary prevention rehabilitation program, and to analyse how different pre-treatment levels of depressive mood during a treatment phase were related to the degree of lifestyle change at 36 months follow-up. SUBJECTS: The study group comprised 109 of the original 183 consecutive coronary artery disease patients (91 male and 18 female) of whom 48 recently had experienced an acute myocardial infarction, 36 had been treated with coronary bypass surgery, 13 with percutaneous transluminal coronary angioplasty, and 12 had angina pectoris that had not been invasively treated. The subjects were divided into 3 subgroups based on their pre-treatment level of depressive mood. METHODS: Depressive mood was assessed at baseline, after 4 weeks and 12 months, using the depression subscale of the Hospital Anxiety and Depression scale. Lifestyle changes analysed included diet, smoking, relaxation (stress management) and exercise. RESULTS: Overall depressive mood ratings were significantly lower, both at the 4-week and 12-month assessments, compared with baseline, with the greatest improvements in patients with higher Hospital Anxiety and Depression measured depression. Original levels of depressive mood were not found to influence change of lifestyle habits during a 36-month follow-up period. CONCLUSION: Depressive mood might not be an obstacle to lifestyle changes when participating in a behaviourally oriented rehabilitation program including exercise-training, which might be a component important for improved depressive mood.

Homeodomain leucine zipper class I genes in Arabidopsis. Expression patterns and phylogenetic relationships.

Members of the homeodomain leucine zipper (HDZip) family of transcription factors are present in a wide range of plants, from mosses to higher plants, but not in other eukaryotes. The HDZip genes act in developmental processes, including vascular tissue and trichome development, and several of them have been suggested to be involved in the mediation of external signals to regulate plant growth. The Arabidopsis (Arabidopsis thaliana) genome contains 47 HDZip genes, which, based on sequence criteria, have been grouped into four different classes: HDZip I to IV. In this article, we present an overview of the class I HDZip genes in Arabidopsis. We describe their expression patterns, transcriptional regulation properties, duplication history, and phylogeny. The phylogeny of HDZip class I genes is supported by data on the duplication history of the genes, as well as the intron/exon patterning of the HDZip-encoding motifs. The HDZip class I genes were found to be widely expressed and partly to have overlapping expression patterns at the organ level. Further, abscisic acid or water deficit treatments and different light conditions affected the transcript levels of a majority of the HDZip I genes. Within the gene family, our data show examples of closely related HDZip genes with similarities in the function of the gene product, but a divergence in expression pattern. In addition, six HDZip class I proteins tested were found to be activators of gene expression. In conclusion, several HDZip I genes appear to regulate similar cellular processes, although in different organs or tissues and in response to different environmental signals.

The homeobox genes ATHB12 and ATHB7 encode potential regulators of growth in response to water deficit in Arabidopsis.

The Arabidopsis thaliana homeodomain leucine-zipper gene ATHB7 , which is active specifically under water deficit conditions, is proposed to act as a negative regulator of growth (Soderman et al ., 1996, Plant J. 10: 375 381; Hjellstrom et al ., 2003, Plant Cell Environ 26: 1127 1136). In this report we demonstrate that the paralogous gene, ATHB12 , has a similar expression pattern and function. ATHB12 ,like ATHB7 ,was up-regulated during water deficit conditions, the up-regulation being dependent on abscisic acid (ABA) and on the activity of the Ser/Thr phosphatases ABI1 and ABI2. Plants that are mutant for ATHB12 , as a result of T-DNA insertions in the ATHB12 gene, showed a reduced sensitivity to ABA in root elongation assays, whereas transgenic Arabidopsis plants expressing ATHB12 and/or ATHB7 as driven by the CaMV 35S promoter were hypersensitive in this response compared to wild-type. High-level expression of either gene also resulted in a delay in inflorescence stem elongation growth and caused plants to develop rosette leaves with a more rounded shape, shorter petioles, and increased branching of the inflorescence stem. Transgenic Arabidopsis plants expressing the reporter gene uidA under the control of the ATHB12 promoter showed marker gene activity in axillary shoot primordia, lateral root primordia, inflorescence stems and in flower organs. Treatment of plants with ABA or water deficit conditions caused the activity of ATHB12 to increase in the inflorescence stem, the flower organs and the leaves, and to expand into the vasculature of roots and the differentiation/elongation zone of root tips. Taken together, these results indicate that ATHB12 and ATHB7 act to mediate a growth response to water deficit by similar mechanisms.

The Arabidopsis homeobox gene, ATHB16, regulates leaf development and the sensitivity to photoperiod in Arabidopsis.

This report describes the characterisation of ATHB16, a novel Arabidopsis thaliana homeobox gene, which encodes a homeodomain-leucine zipper class I (HDZip I) protein. We demonstrate that ATHB16 functions as a growth regulator, potentially as a component in the light-sensing mechanism of the plant. Endogenous ATHB16 mRNA was detected in all organs of Arabidopsis, at highest abundance in rosette leaves. Reduced levels of ATHB16 expression in transgenic Arabidopsis plants caused an increase in leaf cell expansion and consequently an increased size of the leaves, whereas leaf shape was unaffected. Transgenic plants with increased ATHB16 mRNA levels developed leaves that were smaller than wild-type leaves. Therefore, we suggest ATHB16 to act as a negative regulator of leaf cell expansion. Furthermore, the flowering time response to photoperiod was increased in plants with reduced ATHB16 levels but reduced in plants with elevated ATHB16 levels, indicating that ATHB16 has an additional role as a suppressor of the flowering time sensitivity to photoperiod in wild-type Arabidopsis. As deduced from the response of transgenic plants with altered levels of ATHB16 expression in hypocotyl elongation assays, the gene may act to regulate plant development as a mediator of a blue light response.

Depression as a predictor of return to work in patients with coronary artery disease.

The importance of depression in coronary artery disease (CAD) outcomes is being increasingly recognized. The aim of this study was to investigate the power of depression as a predictor of return to work, both at full time and at reduced working hours, within 12 months of participation in a behaviorally oriented rehabilitation program in Sweden. The sample comprised 198 employed patients who had recently experienced an acute myocardial infarction (AMI, n=85), or had been treated with coronary by-pass surgery (CABG, n=73) or coronary angioplasty (PTCA, n=40). The results showed that clinical depression before intervention (>or=16 as measured by the Beck Depression Inventory) exerted a great influence on work resumption both at full-time (odds ratio 9.43, CI=3.15-28.21) and at reduced working-hours (odds ratio 5.44, CI=1.60-18.53), while mild depression (BDI 10-15) influenced only work resumption at full-time (odds ratio 2.89, CI=1.08-7.70). Education and, at full-time hours, age also predicted work resumption. This highlights the importance of depressive symptoms in relation to return to work after a CAD event. More research is needed in order to elaborate the degree to which treatment of depression enhances work resumption rates.