RAPID DETECTION OF MICROBIAL CONTAMINATION IN TRICLOSAN AND HIGH FLUORIDE DENTIFRICES USING AN ATP BIOLUMINESCENCE ASSAY

Abstract The Celsis ATP Bioluminescence method was optimized and validated to detect the presence of microbial contamination in High Fluoride and Triclosan dentifrice formulations. Several enrichment broths were evaluated by using a 24–27 h incubation period. The ATP concentrations of the enrichment broths were found to a range from 0.012 to 0.040 nM. None of the tested enrichment broths were found to exhibit any sample inhibition/enhancement effects on the ATP Bioluminescence reaction. Dentifrice suspensions were inoculated with bacteria, yeast, and mold. All test microorganisms (ca. 1–15 CFU/g) were detected within a 24–27 h incubation period by using TAT Broth Base enrichment broths containing different concentrations of the following ingredients: Tween 20, Neopeptone, Dextrose, Triton X-100, Thiosulfate, Sodium Dibasic Phosphate, and Glycine. Negative ATP response after 24–27 h of incubation at 35C indicates the absence of contamination from these products.     

Pleural Fluid Adenosine Deaminase and Lymphocyte Proportion: Clinical Usefulness In the Diagnosis of Tuberculosis

Adenosine deaminase (ADA) and lymphocyte proportion are known to be independently elevated in tuberculous effusions, but are non-specific, and false positive results are frequent. to overcome this problem the combined use of both parameters was prospectively studied in 276 patients with pleural effusion seen at Porto Alegre, Brazil. Using a cut-off level of 40 U/l at 37°C (method of Giusti¹⁹) for ADA activity and lymphocyte proportion of more than 50%, the correct diagnosis of tuberculosis (sensitivity) was made in 90.7% (CI 87.3–94.1%) of 54 patients. A specificity of 97.7% (CI 95.9–99.5%) was recorded. Five false positive diagnoses of tuberculous effusion were made. Five false negative diagnoses were made: three cases with haematogenous tuberculous dissemination with low ADA levels, and two other patients with low lymphocyte proportion. the combined use of ADA activity determination and lymphocyte proportion is a highly efficient diagnostic strategy of low cost, that merits wider use.     

Species-specific phytoplankton responses to nutrients and zooplankton manipulations in enclosure experiments

1. In situ enclosure experiments were performed in the mesotrophic Bermejales reservoir to evaluate the algal response to changes in the nutrient supply and in the zooplankton size structure and density in a 2 × 2 factorial design. The experiments were conducted during the spring bloom of nanoplanktonic diatoms in 1989. 2. Nutrient enrichment promoted a great increase of phytoplankton biomass indicating a strong nutrient limitation on phytoplankton growth. Total phytoplankton biomass was significantly lower in the Daphina-added enclosures at a given nutrient level and strong direct an indirect effect of zooplankton on phytoplankton community structure and nutrient availability were observed. 3. Most of the nanoplanktonic species were effectively grazed but species with protective coverings and large size colonies were favoured by grazers and small chlorococcales were unaffected probably because of their compensatory high growth rates. The decrease in total biomass imposed by grazers is attributable mainly to the decrease of Cyclotella ocellata, the most abundant species. This taxon suffers two net effects of zooplankton: direct grazing and the indirect decrease of Si availability caused by the growth of C. ocellata which was promoted by P excretion by zooplankton. Indirect effects of grazers on Si availability should, therefore, be taken into account in explaining phytoplankton succession and community structure. 4. In this experiment grazers affected considerably the nanoplanktonic community in Bermejales reservoir. The extent which they were affected, however, depended not only on the algal size as a determinant of edibility but also greatly on the specific nutrient requirements and taxonomic features of the algal species.     

Resource density regulates the foraging investment in higher termite species

1. Resource density can regulate the area that animals use. At low resource density, there is a conflict in terms of balance between costs of foraging and benefits acquired. The foraging of the higher termite Nasutitermes aff. coxipoensis consists of searching throughout trails and a building galleries phase. 2. In this study, a manipulative field experiment was used to test the hypothesis that colonies of N. aff. coxipoensis forage towards a more profitable balance between the establishment of trails and gallery construction at low resource density. 3. The experiment was conducted in north‐eastern Brazil. Seven experimental plots were established with a continuous increase in resource density (sugarcane baits). Entire colonies of N. aff. coxipoensis were transplanted from their original sites to the experimental plot, totalling 35 nests. The number, branches and total length of trails and galleries were quantified. 4. The results show that N. aff. coxipoensis optimises its foraging output, intensifying the establishment of trails at the cost of gallery construction when resource density is low. The number of trails, the number of trail branches and the total length of trails decreased with increasing resource density. Interestingly, at low resource density, the search effort was concentrated on forming longer and a greater number of trails, a small proportion of which were converted into galleries. The opposite relationship was observed at high resource density. 5. These results suggest an optimisation of search efforts during foraging depending on resource density, a mechanism that may help researchers to understand the use of space by higher termite species.     

Population recovery of the sea urchin Lytechinus variegatus in a seagrass flat (Araruama Lagoon,Brazil): the role of recruitment in a disturbed environment

Summary

The size, structure, and density of a population of Lytechinus variegatus were recorded from a shallow seagrass bed (Halodule wrightii) at 40-day intervals from April 1994 to April 1995. A local mass mortality was observed in May 1994. The density declined from 0.57±0.10 to 0.06±0.05 ind.m^?2, mean size declined from 37.6±0.49 to 16.2±2.14 mm and maximum size from 75 to 40 mm. Ten months after mortality, the maximum and mean sizes had returned to initialvalues, but density had not (0.10±0.03 ind.m^?2). A second, smaller mass mortality occurred in April 1995. High values of gonad index were recorded before mortality (9.40±5.97) and after population recovery (11.96±5.74). Recruitment was continuous throughout the year, but reached a peak from August to October. This can he related to the patterns of upwelling in the region. Mass mortality is probably an annual event in this population that can be correlated with the occurrence of low tides during daytime in the fell. The population can recover during the summer when low tides occur during the night. The massive input of recruits prevents extinction of the population during the season of high mortality. Population recovery depends on the magnitude of recruitment.     

Parental care and the transition to independence of Spanish Imperial Eagles Aquila heliaca in Doñana National Park, southwest Spain

The behaviour of five broods of radio-tagged Spanish Imperial Eagles Aquila heliaca adalberti was studied in Doñana National Park, Spain during the post-fledging period. The distance between perching sites and nest, the mean flight duration and distance, the percentage of time spent flying and the home range all increased exponentially with age. As the young got older, the parents spent less time in their vicinity. Young were not seen hunting, but depended on their parents for food. They begged and chased their parents throughout the post-fledging period, with higher intensity at the end. Nevertheless, the adults became progressively more reluctant to feed them, as reflected in the decrease in feeding frequency and in the number of approaching flights towards the young. At the end of the post-fledging period, adults often performed aerial displays and frequently chased their offspring. The age of independence of the different young studied varied between 123 and 145 days. The correlations between individual independence and the dates when the young were last fed by their parents, and when the highest intensity of parental aggressive behaviour occurred, were higher than correlations with the variables related to the maturation of flying. Therefore, it is suggested that parental 'meanness' and aggressive behaviour may be the factors determining the date of juvenile independence and dispersal from the home territory.     

Ferricrocin synthesis in Magnaporthe grisea and its role in pathogenicity in rice

Iron is an essential element for the growth of nearly all organisms. In order to overcome the problem of its low bioavailability, microorganisms (including fungi) secrete siderophores, high-affinity iron chelators. As the acquisition of iron is also a key step in infection processes, siderophores have been considered as potential virulence factors in several host–pathogen interactions. Most fungi produce siderophores of the hydroxamate-type, which are synthesized by non-ribosomal peptide synthetases (NRPSs). Magnaporthe grisea , the causal agent of rice blast disease, produces ferricrocin as intracellular storage siderophore and excretes coprogens. In the M. grisea genome we identified SSM1 , an NRPS gene, and a gene encoding an l -ornithine N5-monooxygenase ( OMO1 ) that is clustered with SSM1 and responsible for catalysing the first step in siderophore biosynthesis, the N⁵ hydroxylation of ornithine. Disruption of SSM1 confirmed that the gene encodes ferricrocin synthetase. Pathogenicity of these mutants towards rice was reduced, suggesting a role of this siderophore in pathogenicity of M. grisea .