Microheterogeneity in 16S ribosomal DNA-defined bacterial populations from a stratified planktonic environment is related to temporal changes and to ecological adaptations

Temporal changes of the bacterioplankton from a meromictic lake (Lake Vilar, Banyoles, Spain) were analyzed with four culture-independent techniques: epifluorescence microscopy, PCR-denaturing gradient gel electrophoresis (DGGE) fingerprinting, fluorescence in situ whole-cell hybridization and flow cytometry sorting. Microscopically, blooms of one cyanobacterium (Synechococcus sp.-like), one green sulfur bacterium (Chlorobium phaeobacteroides-like), and one purple sulfur bacterium (Thiocystis minor-like) were observed at different depths and times. DGGE retrieved these populations and, additionally, populations related to the Cytophaga-Flavobacterium-Bacteroides phylum as predominant community members. The analyses of partial 16S ribosomal DNA sequences from the DGGE fingerprints (550 bp analyzed) revealed higher genetic diversity than expected from microscopic observation for most of these groups. Thus, the sequences of two Synechococcus spp. (both had a similarity of 97% to Synechococcus sp. strain PCC6307 in 16S rRNA), two Thiocystis spp. (similarities to Thiocystis minor of 93 and 94%, respectively), and three Cytophaga spp. (similarities to Cytophaga fermentans of 88 and 89% and to Cytophaga sp. of 93%, respectively) were obtained. The two populations of Synechococcus exhibited different pigment compositions and temporal distributions and their 16S rRNA sequences were 97.3% similar. The two Thiocystis populations differed neither in pigment composition nor in morphology, but their 16S rRNA sequences were only 92.3% similar and they also showed different distributions over time. Finally, two of the Cytophaga spp. showed 96.2% similarity between the 16S rRNA sequences, but one of them was found to be mostly attached to particles and only in winter. Thus, the identity of the main populations changed over time, but the function of the microbial guilds was maintained. Our data showed that temporal shifts in the identity of the predominant population is a new explanation for the environmental 16S rRNA microdiversity retrieved from microbial assemblages and support the hypothesis that clusters of closely related 16S rRNA environmental sequences may actually represent numerous closely related, yet ecologically distinct, populations.     

Environmental impacts of household goods in Europe: a process-based life cycle assessment model to assess consumption footprint

The International Journal of Life Cycle Assessment - Current patterns of household goods consumption generate relevant environmental pressures and impacts. Environmental impacts are not only...     

Fungal Olecranon Bursitis in an Immunocompetent Patient by <Emphasis Type="Italic">Knoxdaviesia dimorphospora</Emphasis> sp. nov.: Case Report and Review

Bursitis is a common medical condition that can occur either with or without infection. We present a case of fungal olecranon bursitis in an immunocompetent individual caused by the new species Knoxdaviesia dimorphospora. It is a dematiaceous filamentous fungus characterized by the production of two different conidia: hyaline and cylindrical, which rise up from phialidic conidiogenous cells located in the upper part of differentiated and unbranched conidiophores, and pale brown and ellipsoidal conidia produced by phialidic conidiogenous cells which are born directly on hyphae. In addition to its morphological peculiarities, the novelty of the fungus was confirmed by sequence analysis of the internal transcribed spacer (ITS) regions and D1/D2 domains of the 28S of the nuclear rRNA gene. The fungal infection was confirmed by cytological examination and repeated cultures. The infection was resolved by surgical debridement and drainage, and the patient presented a complete functional recovery 3 months later. The in vitro antifungal susceptibility to this new human opportunist is provided, terbinafine being the drug with the most potent activity.     

Regional community assembly drivers and microbial environmental sources shaping bacterioplankton in an alpine lacustrine district (Pyrenees,Spain)

Microbial communities in natural ecosystems are subject to strong ecological rules. The study of local communities along a regional metacommunity can reveal patterns of community assembly, and disentangle the underlying ecological processes. In particular, we seek drivers of community assembly at the regional scale using a large lacustrine dataset (>300 lakes) along the geographical, limnological and physico-chemical gradients in the Pyrenees. By using high throughput amplicon sequencing of the 16S rRNA gene, and inferring environmental sources of bacterial immigrants, we showed that surface aquatic bacterial assemblages were strongly influenced by terrestrial populations from soil, biofilms or sediments, and primarily selected by a pH-alkalinity gradient. Indeed, source proportions explained 27% of the community variation, and chemistry 15% of the total variation, half of it shared with the sources. Major taxonomic groups such as Verrucomicrobia, Actinobacteria and Bacteroidetes showed higher aquatic affinities than Parcubacteria, Gammaproteobacteria, Alphaproteobacteria or Betaproteobacteria, which may be recruited and selected through different hydrographic habitats. A regional fingerprint was observed with lower alpha diversity and higher beta diversity in the central Pyrenees than in both ends. We suggest an ecological succession process, likely influenced by complex interactions of environmental source dispersal and environmental filtering along the mountain range geography.     

Oral health awareness in Croatian and Italian urban adolescents

Purpose of this study was to investigate and compare differences in oral health awareness between Croatian and Italian urban adolescents. The sample consisted of primary school last grade students aged between 13 and 15 years, 300 children from Zagreb (Croatia) and 298 children from Bari (Italy). Oral health awareness was evaluated using a self-administered standardized questionnaire. Self-perception of oral health proved to be different between the two groups (p < 0.001). The Croatians reported that their oral health was "excellent" or "very-good" more often than the Italians (68.6% vs. 50.2%). The reasons given for visiting a dentist were different (p < 0.001). The Italians cleaned their teeth more often than the Croatians ("two or more times a day", 83.1% vs. 72.2%, p < 0.003). Wooden toothpicks were preferred by the Croatians (p < 0.001), while floss was preferred by the Italians (p = 0.03). The awareness regarding the use of fluoridated toothpaste was higher in the Italian group (95.6% vs. 72.5%, p < 0.001). The Croatians were consuming sweetened foods more often than the Italians (p < 0.001). Croatian adolescents reported more indicators of a lower level of oral health awareness than the Italians, while on the contrary Croatians had higher esteem of their oral health. Defining national preventive strategies is essential for improving adolescents' attitudes toward oral health in both countries, particularly in Croatia.     

Analysis of kinetic,stoichiometry and regulation of glucose and glutamine metabolism in hybridoma batch cultures using logistic equations

Batch cultures were carried out to study the kinetic, stoichiometry, and regulation of glucose and glutamine metabolism of a murine hybridoma line. Asymmetric logistic equations (ALEs) were used to fit total and viable cell density, and nutrient and metabolite/product concentrations. Since these equations were analytically differentiable, specific rates and yield coefficients were readily calculated. Asymmetric logistic equations described satisfactorily uncontrolled batch cultures, including death phase. Specific growth rate showed a Monod-type dependence on initial glucose and glutamine concentrations. Yield coefficients of cell and lactate from glucose, and cell and ammonium from glutamine were all found to change dramatically at low residual glucose and glutamine concentrations. Under stoichiometric glucose limitation, the glucose-to-cell yield increased and glucose-to-lactate yield decreased, indicating a metabolic shift. Under stoichiometric glutamine limitation the glutamine-to-cell and glutamine-to-ammonium yields increased, but also glucose-to-cell yield increased and the glucose-to-lactate yield decreased. Monoclonal antibody production was mainly non-growth associated, independently of glucose and glutamine levels.     

Genetic study of the population of Tenerife (Canary Islands,Spain): Protein markers and review of classical polymorphisms

Data on six protein polymorphisms (19 alleles) from the human population of Tenerife are presented and discussed along with other classical markers in relation to the origin of the Canarians. Genetic influences from three population groups were considered: the Iberians, and the Berbers and non-Berbers (Arabs) from north Africa. The systems examined show the Tenerife population lies within the limits of variation described for various Iberian groups, with a slight tendency towards the characteristics of north African populations. When blood groups, red cell enzymes and serum protein data were considered, the similarity of the Canary population to Iberians seems strengthened (70% estimated contribution of Iberian peninsula genes to the present-day Canarian pool), while some relation with north African groups is shown. Genetic distances between Canarians and Arabs and Canarians and Berbers are lower than those between the two north African groups, indicating a relative and comparable contribution of each to the present-day gene pool of the Canarian population. The Arab contribution could be attributable to the slaves who were introduced to these islands after the conquest in the 15th century, while the Berber contribution could be the remnants of the extinct aboriginal peoples of the islands (Guanches) or a more recent immigration due to slavery. Genetic data do not allow us to distinguish between these two possibilities. Am. J. Phys. Anthropol. 102:337–349, 1997. © 1997 Wiley-Liss, Inc.