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Publications and source records attributed to J Mas.
Allele frequencies for 15 STR loci (D8S1179, D21S11, D7S820, CSF1PO, D19S433, HUMVWA31A, HUMTPOX, D18S51, D3S1358, HUMTHO1, D13S317, D16S539, D2S1338, D5S818 and HUMFGA) were analysed in the Fang population of Bioko Island, Equatorial Guinea. No deviation from Hardy-Weinberg equilibrium was found for all loci. Statistical parameters demonstrated the forensic utility of the analysed systems.
This paper describes an illuminated reactor that allows the spontaneous development of biofilms aimed at the treatment of sulfide-containing streams. The reactor operates as a sulfidostat and is composed of an illuminated packed-column, in which microorganisms are exposed to constant low substrate concentrations, thereby avoiding inhibition due to high sulfide concentrations. The control system allows highly polluted streams to be oxidized by the microbial biofilm while ensuring the quality of the effluent produced. Both monospecies and multispecies biofilms have been developed. Biofilms undergo changes in light irradiance and sulfide load while providing a consistent reduction of the sulfide levels, down to micromolar concentrations. Both types of biofilm developed differ from stirred reactors in that their specific activities are lower, constituting systems with a slow dynamic behavior and, therefore, they are less sensitive to sudden disturbances.
In the present work, we describe for the first time the utilization of a complex microbial biofilm for the treatment of sulfide-containing effluents. A non-aerated packed-column reactor was inoculated with anoxic lake sediment and exposed to light. A biofilm developed in the column and showed a stable oxidation performance for several weeks. Microbial species composition was analyzed by microscopy, pigment analysis and a bacterial 16S rRNA gene clone library. Colorless sulfur bacteria, green algae and purple sulfur bacteria were observed microscopically. Pigment composition confirmed the presence of algae and purple sulfur bacteria. The clone library was dominated by alpha-Proteobacteria (mostly Rhodobacter group), followed by gamma-Proteobacteria (Chromatiaceae-like and Thiothrix-like aerobic sulfur oxidizers) and the Cytophaga- Flavobacterium- Bacteroides group. Plastid signatures from algae were also present and a few clones belonged to both the beta- ( Rhodoferax sp., Thiobacillus sp.) and delta-Proteobacteria ( Desulfocapsa sp.) and to the low G+C Gram-positive bacteria (Firmicutes group). The coexistence of aerobic, anaerobic, phototrophic and chemotrophic microorganisms in the biofilm, the species richness found within these metabolic groups (42 operational taxonomic units) and the microdiversity observed within some species could be very important for the long-term functioning and versatility of the reactor.
AIMS: Biofilms in water distribution systems represent a far more significant reservoir of micro-organisms than the water phase. Biofilms are (i) resistant to disinfectants, (ii) nuclei for microbial regrowth, (iii) a refuge for pathogens, (iv) accompanied by taste and odour problems, and (v) corrode surfaces. The effects of the current strategies for disinfection of drinking water systems in large buildings (chlorination, copper and silver ionization, and hyper-heating) were compared with a new generation of bismuth thiol (BT) biocides. METHODS AND RESULTS: Multispecies biofilms were treated with 0.8 mg l(-1) of free chlorine, 400 and 40 microg l(-1) of copper and silver ions, respectively, at 55 and 70 degrees C, and bismuth-2,3-dimercaptopropanol (BisBAL). Furthermore, the effect of combined heat and BisBAL on planktonic cell viability was examined in monoculture using Escherichia coli suspensions. Inactivation rates for BisBAL were similar to copper-silver ions, where the effects were slower than for free chlorine or temperature. The BisBAL effect on E. coli monocultures was augmented greatly by increasing temperatures. CONCLUSIONS: Like copper-silver ions, BTs show more persistent residual effects than chlorine and hyper-heating in water systems. BT efficiency increased with temperature. Like copper-silver ions, BT action is relatively slow. SIGNIFICANCE AND IMPACT OF THE STUDY: BT presents a new approach to containing water biofilms. BT action is not as rapid, but is more thorough than chlorine, and less caustic. BTs may also be more efficacious in hot water systems. At sub-minimum inhibition concentration levels, BTs uniquely inhibit bacterial exopolysaccharide, thereby retarding biofilm formation. Thus, the combination of bactericidal and residual effects may prevent slime build-up in hot water systems.
The biting flies Chrysops dimidiatus Wulp and C.silaceus Austen (Diptera: Tabanidae), vectors of Loa loa (Cobbold) (Nematoda: Onchocercidae) on the African mainland, were found to be widespread on the island of Bioko (Equatorial Guinea) during 1996-2001. These tabanids were particularly prevalent in the southern part of Bioko, indicating potential transmission of loiasis on the island. The only other tabanids previously recorded on Bioko, Tabanus argenteus Surcouf (from 1915) and Haematopota near heptagramma Speiser (from 1933), were also collected. The possibility of loiasis being endemic on Bioko contra-indicates ivermectin treatment of onchocerciasis cases, due to risks of adverse side-effects.
Cytotaxonomic analysis of the polytene chromosomes from larvae of the Simulium damnosum Theobald complex from the island of Bioko in Equatorial Guinea is reported, and a new endemic cytoform is described. Chromosomally this cytoform is close to both S. squamosum (Enderlein) and S. yahense Vajime & Dunbar, but is not identical to either. However, it is morphologically and enzymatically identical to S. yahense. The Bioko form was also found to differ from other cytoforms of the S. damnosum complex in West Africa in the copy number or RFLP pattern of several different repetitive DNA sequences. It is clear that the Bioko form is genetically distinct from other populations of the S. damnosum complex, and whilst it is closest to S. yahense, it shows features that suggest a high degree of geographical and genetic isolation. Such isolation is an important consideration in the assessment of the potential for onchocerciasis vector eradication on Bioko.
AIMS: This study was designed to estimate the prevalence of blindness and its main aetiologies in Bioko, an onchocerciasis endemic zone of Equatorial Guinea. METHODS: Random sampling was applied, proportionally to population distribution into urban or rural areas. All the subjects underwent a basic eye examination by trained nurses. In the presence of any ocular affection or a visual acuity of less than 0.3, the subject was visited by the ophthalmologist. This visit included direct and indirect ophthalmoscopy, anterior segment examination with a slit lamp, and intraocular pressure recording. Blindness and visual impairment were defined by using the WHO criteria. RESULTS: 3218 subjects were screened, with a mean age of 34.1 (SD 21.6) years, ranging from 1 month to 102 years (median 34 years). The overall prevalence of blindness was 3.2% (95% CI: 2.6% to 3.9%). Unilateral blindness was present in 4.2%. Visual impairment was diagnosed in 200 patients (6.8%). More than 20% of the acuities inferior to 0.7 improved when explored with a pinhole. The main causes of blindness were cataracts (61.3%); macular affection (25.3%), optic atrophy (16%), and glaucoma (13.3%). Ocular onchocerciasis was detected in 12 cases (0.4%). CONCLUSION: Ocular onchocerciasis was very uncommon in an area of high endemicity. Results also pointed at the lack of basic ophthalmologist eye care and optician resources in the island.
Adenosine-5'-phosphosulfate (APS) reductase participates in the oxidation of sulfite to APS in Allochromatium vinosum. Oxidation of sulfite via the APS pathway yields ATP through substrate-level phosphorylation. An alternative enzyme for the oxidation of sulfite to sulfate, sulfite:acceptor oxidoreductase, has also been reported in Ach. vinosum. Oxidation of sulfite through this enzyme does not yield ATP. APS reductase is expressed constitutively in Ach. vinosum, suggesting that it performs an important role in this organism. However, studies carried out with batch cultures of an APS reductase mutant showed little or no differences in growth or in the rates of substrate oxidation when compared to the wild-type, therefore questioning the role of this enzyme. In an attempt to establish whether the ATP gain derived from APS-reductase-mediated oxidation of sulfite is relevant for energy-limited cultures, we compared growth of the wild-type SM50 and the APS-reductase-deficient mutant D3 when grown in continuous culture under different degrees of illumination. Little differences in the specific growth rates of the two strains were observed at light-limiting irradiances, suggesting that the ATP gained during sulfite oxidation through the APS reductase pathway does not constitute a significant energy input. However, at saturating irradiances, wild-type Ach. vinosum grew considerably faster than the mutant. Increasing the irradiance even further resulted in inhibition of the wild-type strain down to the level of the APS reductase mutant. The implications of these results are discussed.
Allele frequencies for eight STR loci (HUMTH01, HUMVWA31A, HUMCSF1PO, HUMTPOX, D3S1358, D8S1179, D18S51, D19S253) have been analysed in the Bubi population of Bioko Island, Equatorial Guinea. For all loci, no deviation from Hardy-Weinberg equilibrium was found. Data obtained were compared with that of Caucasian and African populations. Significant differences were found for all systems between all the black populations compared and the Caucasoid population. Similarities were observed between the Bubi and Zimbabweans, and also with African American populations. Also, more affinities were observed between Zimbabweans and Ugandans and Ovambos than between these groups and the Bubi population. From these comparisons it is suggested that in Africa, as in other continents, there is a certain genetic heterogeneity.
Pure cultures of phototrophic sulfur bacteria were compared to natural populations that bloom in karstic lakes by electrophoretic analysis of low molecular mass RNA molecules (lmwRNA) and microscopy. Similarities between dominant community members, field isolates and reference strains were established by comparing the lmwRNA band patterns through dendrograms produced with Euclidean distances and the average linkage clustering method, by a single, quick, one-step method. The fingerprinting analysis had three objectives: (i) to compare microbial assemblages from different geographical locations, (ii) to compare those organisms which grow in pure culture to those forming planktonic blooms and (iii) to give a preliminary view of the identity of the predominant community members. The lmwRNA analysis yielded a number of clusters consistent with the microscopic observations and allowed rapid comparison of the microbial communities without the need to isolate their individual components. The fingerprints of natural communities were different from most of the laboratory strains tested. Purple sulfur bacteria responsible for the blooms analyzed in karstic lakes were more closely related to the Thiocystis group than to the classical strains extensively studied in the laboratory.
UNLABELLED: Simultaneous 99mTc sestamibi/201Tl imaging enables the acquisition of images of myocardial stress perfusion and myocardial viability in a single process. One of the major limits of this technique is the crosstalk of the 99mTc downscattered photons into the 201Tl window. We propose using the spectral deconvolution technique photon energy recovery (PER) for correcting this crosstalk. METHODS: A planar line phantom made of 99Tc vertical lines and 201Tl horizontal lines and a cardiac SPECT phantom including an anterior (2 mL) and an inferior (1.5 mL) myocardial fixed defect were used. The phantoms were filled with an initial 99mTc/201Tl ratio of 5:1. Several successive acquisitions were made from time t = 0 to time t = 48 h (99mTc/201Tl ratio approximately 0) without moving the phantoms. Total number of counts, contrast, and normalized SD (NSD) were calculated on the Tl-raw and the Tl-PER planar images. SPECT datasets were analyzed. The Tl-raw images recorded at 48 h were considered the reference "virgin" 201Tl images. RESULTS: Total number of counts, contrast, and NSD ranged from 336% to 201%, 15% to 29%, and 257% to 225% of the virgin 201Tl values, respectively, for Tl-raw planar images; whereas values for Tl-PER images ranged from 128% to 108%, 61% to 79%, and 154% to 108%, respectively. Anterior and inferior defect contrasts ranged from 1.18 to 1.22 and 1.12 to 1.16 for Tl-raw SPECT images, respectively; whereas for Tl-PER images, value ranges were 1.28-1.32 and 1.21-1.24, respectively. The corresponding reference virgin 201Tl values were 1.31 and 1.25 respectively. Summed score, average defect severity, and average defect extent ranges were 4-5, 0.4-0.52, and 4.7-5.9 for Tl-raw images, respectively, and 8-9, 0.59-0.79, and 7.4-8.8 for Tl-PER images. The reference virgin 201Tl values were 9, 0.73, and 8.7, respectively. CONCLUSION: PER is quantitatively efficient to remove 99mTc crosstalk photons from 201Tl images for 99mTc/201Tl ratios ranging from 5:1 to 2:1.
While experiments carried out in Space with isolated cells have shown that eucaryotic cells are able to sense and respond to the absence of gravity by modifying their reactions, experiments in which more complex processes have been investigated, such as Biological Systems undergoing development under Microgravity, have been surprisingly unaffected by the space environment. This can be considered a curious result since all organisms are evolutionarily adapted to the current level of the gravity force in our planet and should eventually change if this parameter will vary in a permanent manner. In fact, the small effects of the modifications in gravity on development in short term experiments may be equivalent to the difficulties in detecting the involvement of other basic physical processes such as diffusion-controled auto-organizative reactions in currently developing biological systems. An apparent exception to this lack of effect is experiments where brine shrimp dormant gastrulae directly exposed to the space environment accumulate developmental defects as a consequence of cosmic irradiation. In this article we discuss the idea that at a certain stage during the evolutionary emergence of multicellular organisms the cues laid by generic forces such as gravity were involved in the evolutionary organization of these primitive organisms. As evolution proceed, these early mechanisms may have been obscured and/or made redundant by the appearance of new internal, environment-independent biological regulatory mechanisms. On the other hand, behavioral responses that may be important, for example, in setting the life-spans of organisms may still be more readily susceptible to manipulation by external cues as experiments carried out by our group in Space and on the ground with Drosophila melanogaster indicate. Grant Numbers: ESP-1775.
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This article analyzes how absorption of light by suspensions of phototrophic bacteria is modulated by changes in the biomass of the culture, the size of the culture vessel and by the presence of refractile structures within the cells. Increases in biomass and culture size result in higher rates of light absorption but in the decrease of the amount of energy available per cell. The presence of refractile structures has different consequences depending on the biomass concentration. In dense cultures, the accumulation of refractile structures increases the reflection of light, and also reduces specific light absorption. In diluted cultures, however, the effect is the opposite, and refractile structures seem to increase light absorption.
Metrifonate is converted nonenzymatically to 2.2, dimethyl dichlorovinyl phosphate (DDVP), an inhibitor of acetylcholinesterase (AChE). This 21-day, randomized, double-blind, placebo-controlled trial of metrifonate in patients with Alzheimer's disease (n = 27) evaluated four doses, each administered orally once daily. All patients received a loading dose (LD) for 6 days followed by a maintenance dose (MD) for 15 days. The treatment groups were: panel 1, LD = 1.5 mg/kg (75-135 mg), MD = 0.25 mg/kg (12.5-25 mg); panel 2, LD = 2.5 mg/kg (125-225 mg), MD = 0.40 mg/kg (20-35 mg); panel 3, LD = 4.0 mg/kg (200-335 mg), MD = 0.65 mg/kg (30-60 mg); and panel 4, LD = 4.0 mg/kg (200-335 mg), MD = 1.0 mg/kg (50-90 mg). All metrifonate doses were well tolerated. Most adverse events were mild to moderate in intensity, gastrointestinal in nature, and transient. Mean area under the concentration-time curve (AUC) and maximum concentration (Cmax) for both metrifonate and DDVP increased in relation to dose. Metrifonate and DDVP had similar, largely dose-independent mean values for time to Cmax (tmax) and half-life (t1/2). There was little or no accumulation of either metrifonate or DDVP with long-term administration. After 21 days of treatment, mean percent erythrocyte AChE inhibition was 14%, 35%, 66%, 77%, and 82% for placebo and panels 1 through 4, respectively. Cognitive improvement was observed with the two highest metrifonate doses. These results reflect favorable safety and pharmacokinetic profiles for the use of metrifonate in the treatment of Alzheimer's disease.
Several phototrophic sulfur bacteria were identified preliminarily through the analysis of the low-molecular-weight RNA fraction (lmwRNA) of bacterial cells. This fraction includes the ribosomal 5S RNA and several transfer RNAs. These molecules were separated by high-resolution electrophoresis in polyacrylamide gels, and the resulting band patterns were used as fingerprints for the identification of the organisms. We examined a large number of well-characterized reference strains together with a broad range of purple sulfur bacterial isolates from freshwater and marine environments. A cluster analysis was run using the similarity matrix calculated from the band patterns. Despite the shortcomings of the method, close relatives were clustered together yielding a number of groups consistent with the phylogenetic arrangement established through the analyses of a few available 16S rRNA gene sequences. Thus, the classification obtained gives further support to rearrangement of the group as the analyses of 16S rRNA gene sequences had previously suggested. We conclude that the analysis of lmwRNA band patterns is a rapid and simple tool for grouping and preliminarily identifying new isolates of phototrophic sulfur bacteria.
The photosynthetic response of the purple sulfur bacterium Chromatium vinosum DSM 185 to different degrees of illumination was analyzed. The microorganism was grown in continuous culture, and samples were taken from the effluent of the culture and incubated at different irradiances to determine the specific rate of sulfur oxidation as a measure of the photosynthetic activity of the organism. The activities obtained were plotted as a function of the specific rate of light uptake, and for each set of data a photosynthesis equation was fitted, which allowed the estimation of Pmax (photosynthetic capacity), qk (the threshold irradiance for light limitation), and m (maintenance coefficient). The results indicated that cells grown under light limitation are able to achieve higher photosynthetic activities than cells grown under light saturation. The photosynthetic capacity (Pmax) remained constant under all the conditions of illumination tested, while the maintenance expenses (m) were higher under light limitation. The parameter qk, on the contrary, decreased considerably at limiting irradiances.
This study describes how the phototrophic organism Chromatium vinosum, when grown under different degrees of light limitation, distributes the reducing power initially present in the medium as hydrogen sulfide. Under all the conditions of illumination tested, sulfur was the major store of reducing power. Glycogen, which was virtually absent under light limitation, accounted for 31.6% of the stored reducing power at saturating irradiances. Analysis of the electron budget showed that under light-limiting conditions, an important fraction of reducing power did not appear in storage products or in structural cell material. Analysis of dissolved organic carbon in the supernatant of the culture indicated the excretion of organic compounds.