No abstract

Ethanolic fermentation is classically associated with flooding tolerance when plant cells switch from respiration to anaerobic fermentation. However, recent studies have suggested that fermentation also has important functions in the presence of oxygen, mainly in germinating pollen and during abiotic stress. Pyruvate decarboxylase (PDC), which catalyzes the first step in this pathway, is thought to be the main regulatory enzyme. Here, we characterize the PDC gene family in Arabidopsis. PDC is encoded by four closely related genes. By using real-time quantitative polymerase chain reaction, we determined the expression levels of each individual gene in different tissues, under normal growth conditions, and when the plants were subjected to anoxia or other environmental stress conditions. We show that PDC1 is the only gene induced under oxygen limitation among the PDC1 gene family and that a pdc1 null mutant is comprised in anoxia tolerance but not other environmental stresses. We also characterize the expression of the aldehyde dehydrogenase (ALDH) gene family. None of the three genes is induced by anoxia but ALDH2B7 reacts strongly to ABA application and dehydration, suggesting that ALDH may play a role in aerobic detoxification of acetaldehyde. We discuss the possible role of ethanolic fermentation as a robust back-up energy production pathway under adverse conditions when mitochondrial function is disturbed.The ethanolic fermentation pathway branches off the main glycolytic pathway at pyruvate. In the first step, pyruvate is the substrate of pyruvate decarboxylase (PDC), yielding CO 2 and acetaldehyde. Subsequently, acetaldehyde is reduced to ethanol with the concomitant oxidation of NADH to NAD ϩ by alcohol dehydrogenase (ADH). In the present day aerobic atmosphere, ethanolic fermentation is used only by specialized organisms or under particular conditions. In plants, it has been studied because of its relevance in flooding tolerance where plant cells switch from aerobic respiration to anaerobic fermentation (for review, see Drew, 1997).ADH has been the subject of numerous genetic studies, and adh mutants have been reported for a number of species, including maize (Zea mays; for review, see Freeling and Bennett, 1985), tobacco (Nicotiana tabacum; Rousselin et al., 1990), and Arabidopsis (Jacobs et al., 1988). Maize adh null mutants are sensitive to strict anoxia but no obvious phenotype is apparent in acclimated plants (Johnson et al., 1994). Experiments with isogenic maize lines differing in ADH activity over a approximately 200-fold range indicated that ADH activity does not limit the capacity for energy production by ethanolic fermentation unless there is a reduction in activity to less than 1% of wild-type levels (Roberts et al., 1989).These results suggest that ADH is present in large excess and are inconsistent with the idea of ADH as the regulatory enzyme of this pathway.Overexpression of a bacterial PDC in transgenic tobacco resulted in constitutive high and active protein levels under both normoxic an...

The first commercial indirect immunofluorescence assay (IFA) using Euroimmun Biochip technology was evaluated for the serodiagnosis of immunoglobulin G (IgG) and IgM antibodies against yellow fever virus (YFV) and was compared with the plaque reduction neutralization test (PRNT), which is currently the gold standard test for YFV. An overall correlation between the tests of 98.7% was established based on the analysis of 150 sera from individuals after vaccination with the 17D yellow fever vaccine. The sensitivity and specificity, calculated using the 150 sera from vaccinees and 150 sera from healthy blood donors, were 95% and 95%, respectively, for the IgG IFA and 94% and 97% for the IgM IFA. Antibody titers found in the PRNT correlated poorly with the IgM and IgG titers detected by IFA. The analysis of preexisting heterologous flaviviral immunity revealed the presence of antibodies reactive with YFV, tick-borne encephalitis virus, West Nile virus, Japanese encephalitis virus, and dengue virus serotypes 1 to 4 in 20 out of the 150 vaccinees. The indirect IFA showed that nine of these individuals with previous flaviviral exposure who received 17D vaccine failed to produce detectable IgM antibodies. Despite this preexisting immunity, all vaccinees developed protective immunity as detected by PRNT and anti-YFV IgG antibodies as detected by IFA. The high specificity and sensitivity of the IFA make it a useful tool for rapid diagnosis of yellow fever during outbreaks, for epidemiological studies, and for serosurveillance after vaccination.

The virosome-adjuvanted influenza vaccine showed greater immunogenicity over the split influenza vaccine in unprimed children and showed a trend toward better immunogenicity in the rest of the study population. Both vaccines were well-tolerated.