The limits to genomic predictions: role of sigma(N) in environmental stress survival of Pseudomonas putida

Based on genomic data and on the phenotypes of an FlhF mutant of Pseudomonas putida, the alternative sigma factor sigma(N) (sigma(54)) has been proposed to play a key role in survival to various nutritional and environmental stresses in this bacterium. Quite in contrast, we show that unlike sigma(S) (sigma(38)) the loss of sigma(N) does not impair to any significant extent the ability of P. putida to survive long-term starvation. rpoN mutants (lacking sigma(N)) are indistinguishable from the wild-type with respect to solvent tolerance, resistance to heat shock or sensitivity to hydrogen peroxide. These data suggest that while sigma(N) is a key component of expression of alternative biodegradative pathways for unusual carbon sources (i.e. m-xylene or dimethylphenols), its loss does not compromise bacterial endurance to gross types of environmental stress. Moreover, these results point out the limitations, if not the deception, of genomic predictions when confronted with experimental data.     

Single-chain antibody fragments specific to the hepatitis B surface antigen, produced in recombinant tobacco cell cultures

An anti-hepatitis B surface antigen (HBsAg), single-chain Fv antibody fragment (scFv) with a 6-histidine N-terminal tag was produced in cultured transgenic tobacco cells. Western blot and antigen-specific chromatography showed high levels of biologically active scFv in the culture supernatant (1 mg l^–1) and in cells (5 mg kg^–1). A simple one-step scFv purification was developed using immobilized metal ion affinity chromatography.     

Reproduction, age, growth and mortality of axillary seabream, Pagellus acarne (Sparidae), from the Canarian archipelago

Axillary seabream Pagellus acarne (Risso 1826) caught off the Canary Islands from January 1991 to December 1994 were studied. The length range of the catches was between 11 and 31 cm, with a modal distribution between 17 and 21 cm. The overall ratio of males to females was 1:1.74. Males were observed up to a length of 24 cm. Hermaphrodites were recorded at lengths between 15 and 23 cm. The species was characterized by protandric hermaphroditism. The reproductive season extended from October to March, with a peak in spawning activity in December–January. The size at sexual maturity was 15.8 cm total length (2 years old) for males and 19.4 cm total length (3 years old) for females. The total length–total weight relationship for the entire population is described by the parameters a = 0.0068, and b = 3.2401. Otolith age readings showed that the population exploited consisted of 10 age groups (1–10 years), including a very high proportion of individuals between 1 and 4 years old. The von Bertalanffy growth parameters for all individuals were L_∞ = 32.98 cm, k = 0.22 years⁻¹, and t₀ = −0.87 years. Males grew comparatively slower than females. The instantaneous rates of mortality for all fish were Z = 0.96 years⁻¹, M = 0.30 years⁻¹, and F = 0.66 years⁻¹. The exploitation ratio and the length at first capture were, respectively, E = 0.69 and LC₅₀ = 16.1 cm. The stock is overexploited, therefore measures such as closed seasons or changes in fishing patterns would be desirable to safeguard the spawning stock and recruits.     

Evaluation of the effect of some biocides against organisms isolated from historic monuments

On the surfaces of monuments and buildings, organic and inorganic pollutants accumulate, as well as various microbial communities which contribute to stone decay. In order to control these organisms, we have tested some chemical products with biocide and water-repellent properties. Some of these products were tested in an agar diffusion test and on limestone slabs. Efficacy of the products and the microbial inhibition were studied with scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM) techniques. This revised version was published online in June 2006 with corrections to the Cover Date.     

Analytic assessment of the various bioimpedance methods used to estimate body water

Knowledge of patient fluid distribution would beuseful clinically. Both single-frequency (SF) and impedance modelingapproaches are proposed. The high intercorrelation between body watercompartments makes determining the best approach difficult. This studywas conducted to evaluate the merits of an SF approach. Mathematical simulation was performed to determine the effect of tissue change onresistance and reactance. Dilution results were reanalyzed, andresistance and parallel reactance were used to predict the intracellular water for two groups. Results indicated that the amountof intracellular and extracellular water conduction at any SF can varywith tissue change, and reactance at any SF is affected by all tissueparameters. Modeling provided a good prediction of dilutionintracellular and extracellular water, but an SF method did not.Intracellular, extracellular, and total body water were equallypredicted at all frequencies by SF resistance and parallel reactance.Extracellular and intracellular water are best measured throughmodeling, because only at the zero and infinite frequencies are theresults sensitive only to extracellular and intracellular water. At allother frequencies there are other effects.

     

Monitoring of clinical signs in goats with transmissible spongiform encephalopathies

Background  

As there is limited information about the clinical signs of BSE and scrapie in goats, studies were conducted to describe the clinical progression of scrapie and BSE in goats and to evaluate a short clinical protocol for its use in detecting scrapie-affected goats in two herds with previously confirmed scrapie cases. Clinical assessments were carried out in five goats intracerebrally infected with the BSE agent as well as five reported scrapie suspects and 346 goats subject to cull from the two herds, 24 of which were retained for further monitoring. The brain and selected lymphoid tissue were examined by postmortem tests for disease confirmation.