Fluorescence-Tagged Transgenic Lines Reveal Genetic Defects in Pollen Growth—Application to the Eif3 Complex

BACKGROUND: Mutations in several subunits of eukaryotic translation initiation factor 3 (eIF3) cause male transmission defects in Arabidopsis thaliana. To identify the stage of pollen development at which eIF3 becomes essential it is desirable to examine viable pollen and distinguish mutant from wild type. To accomplish this we have developed a broadly applicable method to track mutant alleles that are not already tagged by a visible marker gene through the male lineage of Arabidopsis. METHODOLOGY/PRINCIPAL FINDINGS: Fluorescence tagged lines (FTLs) harbor a transgenic fluorescent protein gene (XFP) expressed by the pollen-specific LAT52 promoter at a defined chromosomal position. In the existing collection of FTLs there are enough XFP marker genes to track nearly every nuclear gene by virtue of its genetic linkage to a transgenic marker gene. Using FTLs in a quartet mutant, which yields mature pollen tetrads, we determined that the pollen transmission defect of the eif3h-1 allele is due to a combination of reduced pollen germination and reduced pollen tube elongation. We also detected reduced pollen germination for eif3e. However, neither eif3h nor eif3e, unlike other known gametophytic mutations, measurably disrupted the early stages of pollen maturation. CONCLUSION/SIGNIFICANCE: eIF3h and eIF3e both become essential during pollen germination, a stage of vigorous translation of newly transcribed mRNAs. These data delimit the end of the developmental window during which paternal rescue is still possible. Moreover, the FTL collection of mapped fluorescent protein transgenes represents an attractive resource for elucidating the pollen development phenotypes of any fine-mapped mutation in Arabidopsis

716-3 Prognostic Significance of Transient Ischemic Episodes; Response to Treatment Shows Improved Prognosis. Results of the TIBBS-follow-up

TIBBS is a multi-center trial in which patients with stable angina pectoris and a positive exercise ECG were selected for randomized medical treatment when they showed transient ischemic episodes (TIE) on 48-h-ambulatory ECG monitoring (AECG). The follow-up study at 1 year investigates the implications for the prognosis of the patients, of 621 patients screened on the basis of history of stable angina pectoris and positive exercise ECG, 565 had technically sufficient 48-h-AECG. and 193 showed 0 or 1 TIE (1mm, 1min, 1min. apart) 152 showed 2-6 TIE. 153 showed >6 TIE. Follow-up at one year was >90% complete, Physicians in charge of the patients were unaware of the results of AECG. Patients with 0-1 TIE had less cardiac events (death. AMI, CABG, PTCA, hospitalisation for unstable A.p.) at one year (11.9%) compared to patients with 2-6 TIE (+26.3%) or patients with >6 TIE (30.5%) (p<0.001). Of 268 randomized patients. those 90 patients who had shown response to medical treatment with 100% reduction of TIE during the 8-week active phase of TIBBS (treatment with Bisoprolol 10mg/20 mg o,d. vs. Nifedipin slow release 2×20/2×40mg b.i.d.) had better prognosis: 17.8% events compared to 30.6% events in patients with less or no reduction of TIE (p<0,025). Patients who responded with 50% reduction of TIE showed only a trend towards reduced risk of events: 23.3% vs 30.9% (p<0,117).ConclusionAECG in patients with stable angina pectoris and positive exercise ECG selects patients with increased risk of cardiac events. Patients who do not respond to medical treatment with reduction of TIE are at further increased risk