Improved robustness of an ethanologenic yeast strain through adaptive evolution in acetic acid is associated with its enzymatic antioxidant ability.

AIMS: To investigate multiple tolerance of Saccharomyces cerevisiae obtained through a laboratory strategy of adaptive evolution in acetic acid, its relation with enzymatic ROS detoxification and bioethanol 2G production. METHODS AND RESULTS: After adaptive evolution in acetic acid, a clone (Y8A) was selected for its tolerance to high acetic acid concentrations (13 g l-1 ) in batch cultures. Y8A was resistant to multiple stresses: osmotic, thermic, oxidative, saline, ethanol, organic acid, phenolic compounds and slow freeze-thawing cycles. Also, Y8A was able to maintain redox homeostasis under oxidative stress, whereas the isogenic parental strain (Y8) could not, indicating higher basal activity levels of antioxidative enzyme Catalase (CAT) and Gluthatione S-transferase (GST) in Y8A. Y8A reached higher bioethanol levels in a fermentation medium containing up to 8 g l-1 of acetic acid when compared to parental strain Y8. CONCLUSIONS: A multiple-stress-tolerant clone was obtained using adaptive evolution in acetic acid. Stress cross-tolerance could be explained by its enzymatic antioxidative capacity, namely CAT and GST. SIGNIFICANCE AND IMPACT OF THE STUDY: We demonstrate that adaptive evolution used in S. cerevisiae was a useful strategy to obtain a yeast clone tolerant to multiple stresses. At the same time, our findings support the idea that tolerance to oxidative stress is the common basis for stress cotolerance, which is related to an increase in the specific enzymes CAT and GST but not in Superoxide dismutase, emphasizing the fact that detoxification of H2 O2 and not O2 ˙ is a key condition for multiple stress tolerance in S. cerevisiae.

Miniemulsion polymerizations of n-butyl cyanoacrylate via two routes: towards a control of particle degradation.

This study aimed at determining the influence of the mechanism of polymerization on the molar mass and degradation of poly(n-butyl cyanoacrylate) (PBCA) nanoparticles obtained by miniemulsion polymerization. Therefore, nanoparticles of poly(n-butyl cyanoacrylate) were synthesized via radical and/or anionic miniemulsion polymerization stabilized by Brij®78, a POE based surfactant. Polymerization conditions had little influence on the final diameter while it severely affected the final molar masses of PBCA. An increase of the temperature and of the pH of the continuous phase led to higher molar masses. A further increase was observed when a radical initiator was added in the monomer. The evolution of the molar mass of the synthesized poly(n-butyl cyanoacrylate) was followed as a function of time at pH 7.4 by Size Exclusion Chromatography. As expected, the degradation kinetics strongly depended on the polymerization mechanism (anionic or radical).

Abdominal and fetal echography tele-operated in several medical centres sites, from an expert center, using a robotic arm & telephone or satellite link.

OBJECTIVE: to design and validate a method for tele-operating (from an expert site) an echographic examination in an isolated site where the patient stays. METHOD: A dedicated robotic arm (ESTELE) holding a real ultrasound probe is remotely controlled from the expert site with a fictive probe, and reproduces on the real probe all the movements of the expert hand. The isolated places, are areas with reduced medical facilities, (secondary hospitals 20 to 100 km from the main hospital in Europ, dispensaries in Africa, Amazonia, the a rescue vehicles.... RESULTS: ESTELE was tested on 87 adults and 29 pregnant with ISDN or satellite lines. During fetal tele-operated echography the expert was able to perform appropriate views of the fetal structures in 95% of the cases. During exploration of adult abdomen the expert visualized the main organs in 87% of the cases. Presently the ESTELE system is installed in 4 secondary hospitals, 40 to 100 km from our University Hospital and tele-operated daily by our staff. CONCLUSION: Robotized tele-echography provide similar information as direct examination. No false diagnostic was reported. Moreover the patients were examined by an expert from the University Hospital while staying in the Medical center proximal to their home.

Fetal tele-echography using a robotic arm and a satellite link.

OBJECTIVE: To design a method for conducting fetal ultrasound examinations in isolated hospital sites using a dedicated remotely controlled robotic arm (tele-echography). METHODS: Tele-echography was performed from our hospital (expert center) on 29 pregnant women in an isolated maternity hospital (patient site) 1700 km away, and findings were compared with those of conventional ultrasound examinations. At the patient site, a robotic arm holding the real ultrasound probe was placed on the patient's abdomen by an assistant with no experience of performing ultrasound. The robotic arm, remotely controlled with a fictive (expert) probe, reproduced the exact movements (tilting and rotating) of the expert hand on the real ultrasound probe. RESULTS: In 93.1% of the cases, all biometric parameters, placental location and amniotic fluid volume, were correctly assessed using the teleoperated robotic arm. In two cases, femur length could not be correctly measured. The mean duration of fetal ultrasound examination was 14 min (range, 10-18) and 18 min (range, 13-23) by conventional and tele-echography methods, respectively. The mean number of times the robotic arm was repositioned on the patient's abdomen was seven (range, 5-9). CONCLUSION: Tele-echography using a robotic arm provides the main information needed to assess fetal growth and the intrauterine environment within a limited period of time.

The robot and the satellite for tele-operating echographic examination in Earth isolated sites, or onboard ISS.

UNLABELLED: The objective was to design and validate a method for tele-operating (from an expert site) an echographic examination in an isolated site. METHOD: The isolated places, defined as areas with reduced medical facilities, could be secondary hospitals 20 to 50 km from the university hospital, or dispensaries in Africa or Amazonia, or a moving structure like a rescue vehicle or the International Space Station (ISS). At the expert center, the ultrasound medical expert moves a fictive probe, connected to a computer (n degrees 1) which sends, the coordinate changes of this probe via an ISDN or satellite line to a second computer (n degrees 2), located at the isolated site, which applies them to the robotic arm holding the real echographic probe. RESULTS: The system was tested at Tours Hospital on 105 patients. A complete investigation (visualization) of all the organs requested for different clinical cases was obtained in 76% of the cases with the robot, and 87% at the reference echography: In 11% of the cases, at least one of the organ visualized at reference echo could not be investigated by the robot, thus the diagnostic was not done. The number of repositioning was higher for the robot (6.5 +/- 2) than for the reference echo (5.1 +/- 2 = or > 24% more with robot). The duration of the examination was higher with the robot (16 +/- 10 min) than for the reference echography (11 +/- 4 min = or > +43% with the robot compare to reference echography. The system was also tested successfully using satellite links in a limited number of cases (approx 30).

Functional isolation of the Candida albicans FCR3 gene encoding a bZip transcription factor homologous to Saccharomyces cerevisiae Yap3p.

We have isolated a C. albicans gene, named FCR3 (for fluconazole resistance 3), based upon its ability to suppress the FCZ hypersusceptibility of a Saccharomyces cerevisiae mutant strain (JY312) lacking the transcription factors Pdr1p and Pdr3p. The FCR3 ORF (1200 bp) encodes a 399 amino acid protein containing a basic leucine zipper (bZip) domain. Fcr3p displays the highest level of sequence homology with the S. cerevisiae Yap3p protein (34% identity, 45% similarity). We had previously shown that deletion of the PDR5 gene encoding a multidrug transporter completely abolished the ability of FCR3 to suppress the FCZ hypersusceptibility of JY312, suggesting that FCR3 confers FCZ resistance by activating PDR5 expression. We show here that the beta-galactosidase activity of a PDR5 promoter-lacZ construct in JY312 is increased two-fold upon FCR3 overexpression, demonstrating that FCR3 regulates PDR5 at the transcriptional level. We also show that FCR3 overexpression not only suppresses the hypersusceptibility of JY312 to 4-nitroquinoline-N-oxide (4-NQO) but also confers higher levels of resistance to this compound as compared to the wild-type KY320 strain. Since PDR5 is not involved in 4-NQO resistance, this result indicates that FCR3 can also activate the transcription of other genes that can confer 4-NQO resistance. Finally, Northern blot analysis indicates that FCR3 encodes a single 2.4 kb RNA transcript in C. albicans, suggesting that the FCR3 mRNA contains long 5' and/or 3' untranslated regions. The nucleotide sequence of the FCR3 gene has been deposited at GenBank under Accession No. AF342983.

Pseudoknots in prion protein mRNAs confirmed by comparative sequence analysis and pattern searching.

The human prion gene contains five copies of a 24 nt repeat that is highly conserved among species. An analysis of folding free energies of the human prion mRNA, in particular in the repeat region, suggested biased codon selection and the presence of RNA patterns. In particular, pseudoknots, similar to the one predicted by Wills in the human prion mRNA, were identified in the repeat region of all available prion mRNAs available in GenBank, but not those of birds and the red slider turtle. An alignment of these mRNAs, which share low sequence homology, shows several co-variations that maintain the pseudoknot pattern. The presence of pseudoknots in yeast Sup35p and Rnq1 suggests acquisition in the prokaryotic era. Computer generated three-dimensional structures of the human prion pseudoknot highlight protein and RNA interaction domains, which suggest a possible effect in prion protein translation. The role of pseudoknots in prion diseases is discussed as individuals with extra copies of the 24 nt repeat develop the familial form of Creutzfeldt-Jakob disease.