Effect of hyperbaric stress on yeast morphology: Study by automated image analysis

The effects of hyperbaric stress on the morphology of Saccharomyces cerevisiae were studied in batch cultures under pressures between 0.1 MPa and 0.6 MPa and different gas compositions (air, oxygen, nitrogen or carbon dioxide), covering aerobic and anaerobic conditions. A method using automatic image analysis for classification of S. cerevisiae cells based on their morphology was developed and applied to experimental data. Information on cell size distribution and bud formation throughout the cell cycle is reported. The results show that the effect of pressure on cell activity strongly depends on the nature of the gas used for pressurization. While nitrogen and air to a maximum of 0.6 MPa of pressure were innocuous to yeast, oxygen and carbon dioxide pressure caused cell inactivation, which was confirmed by the reduction of bud cells with time. Moreover, a decrease in the average cell size was found for cells exposed for 7.5 h to 0.6 MPa CO2.CAPES and CNPq (Brazil). Fundação para a Ciência e Tecnologia (Portugal)

The Dyad Symmetry Element of Epstein-Barr Virus Is a Dominant but Dispensable Replication Origin

OriP, the latent origin of Epstein-Barr virus (EBV), consists of two essential elements: the dyad symmetry (DS) and the family of repeats (FR). The function of these elements has been predominantly analyzed in plasmids transfected into transformed cells. Here, we examined the molecular functions of DS in its native genomic context and at an ectopic position in the mini-EBV episome. Mini-EBV plasmids contain 41% of the EBV genome including all information required for the proliferation of human B cells. Both FR and DS function independently of their genomic context. We show that DS is the most active origin of replication present in the mini-EBV genome regardless of its location, and it is characterized by the binding of the origin recognition complex (ORC) allowing subsequent replication initiation. Surprisingly, the integrity of oriP is not required for the formation of the pre-replicative complex (pre-RC) at or near DS. In addition we show that initiation events occurring at sites other than the DS are also limited to once per cell cycle and that they are ORC-dependent. The deletion of DS increases initiation from alternative origins, which are normally used very infrequently in the mini-EBV genome. The sequence-independent distribution of ORC-binding, pre-RC-assembly, and initiation patterns indicates that a large number of silent origins are present in the mini-EBV genome. We conclude that, in mini-EBV genomes lacking the DS element, the absence of a strong ORC binding site results in an increase of ORC binding at dispersed sites

Measurement of Trilinear Gauge Couplings in e+e−e^+ e^- Collisions at 161 GeV and 172 GeV

Trilinear gauge boson couplings are measured using data taken by DELPHI at 161~GeV and 172~GeV. Values for $WWV$ couplings ($V=Z, \gamma$) are determined from a study of the reactions \eeWW\ and \eeWev, using differential distributions from the $WW$ final state in which one $W$ decays hadronically and the other leptonically, and total cross-section data from other channels. Limits are also derived on neutral $ZV\gamma$ couplings from an analysis of the reaction \eegi

Search for neutral heavy leptons produced in ZZ decays

Weak isosinglet Neutral Heavy Leptons (νm) have been searched for using data collected by the DELPHI detector corresponding to 3.3 × 106 hadronic Z0 decays at LEP1. Four separate searches have been performed, for short-lived νm production giving monojet or acollinear jet topologies, and for long-lived νm giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(Z0 → νmν̄) of about 1.3 × 10-6 at 95% confidence level for νm masses between 3.5 and 50 GeV/c2. Outside this range the limit weakens rapidly with the νm mass. The results are also interpreted in terms of limits for the single production of excited neutrinos. © Springer-Verlag 1997

Cassava starch processing at small scale in North Vietnam

In Northern Vietnam, small-scale cassava starch processing is conducted in densely populated craft villages, where processors face difficulties to expand their activities. Three different processing systems were studied among a cluster of three communes in the Red River Delta, producing up to 430 t of starch (at 55% dry matter) per day. The first system, type A, is a cylindrical rasper and a manual sieve, the second, type B, is a cylindrical rasper and stirring-filtering machine and the third, type C, used equipment for both the rasping and filtering stages. Moisture, starch, crude fibers and ash content analysis were carried out on samples collected from the A-B-C manufacturing processes to establish the mass balance of starch. Production capacity, water consumption, electrical requirements and capital-labor costs per tonne of starch (12% moisture) were also reported. A-B-C manufacturing processes enabled 75% recovery of the starch present in fresh roots. No significant change was observed in the composition of starch. Upgrading from system A to B and subsequently to C resulted in an increase in the extraction capacities (up to 0.9 t of peeled roots per hour), the extraction efficiencies during the extraction stage (up to 93%), and an increase in the water consumption and electrical power (up to 21 m3 and 55 kWh per tonne of starch, respectively). The highest amount of total solids carried in the waste-water was obtained with type C (up to 17% of the dry weight of fresh roots, compared to 10% and 13% for type A and B, respectively). This may lead to a higher chemical oxygen demand (COD) and biological oxygen demand (BOD) in waste-water, which can result in more polluted waste-water than compared with the type A and B technologies. Upgrading the rasping-extraction technologies also resulted in higher profits and reduction of labor per tonne of starch (up to 18 US$ and 26 man-hours respectively). The diagnosis proposed in this study can be applied in different contexts to recommend technological options by considering space, energy and capital-labor availabilities