Search results for " Population"

Recent expansion of Northeast Atlantic and Mediterranean populations of Melicertus (Penaeus) kerathurus (Crustacea: Decapoda).

2009

We analysed the genetic diversity of Melicertus kerathurus (Penaeidae), a commercially valuable penaeid shrimp that is distributed in the Mediterranean Sea and eastern Atlantic Ocean. We examined the polymorphism of a 494 bp DNA segment of the mitochondrial COI region in 173 individuals, sampled in nine Mediterranean and two Atlantic samples, covering the whole range of the species from the tropical waters of the Gulf of Guinea to the eastern part of the Mediterranean Sea. The mean nucleotide and haplotype diversities were π = 0.00275 and h = 0.718, respectively, for the global data set, with the highest values occurring in the African samples and the lowest in the Adriatic Sea. A clear sam…

Geothermal Gases Shape the Microbial Community of the Volcanic Soil of Pantelleria, Italy

2020

The Favara Grande nature reserve on the volcanic island of Pantelleria (Italy) is known for its geothermal gas emissions and high soil temperatures. These volcanic soil ecosystems represent “hot spots” of greenhouse gas emissions. The unique community might be shaped by the hostile conditions in the ecosystem, and it is involved in the cycling of elements such as carbon, hydrogen, sulfur, and nitrogen. Our metagenome study revealed that most of the microorganisms in this extreme environment are only distantly related to cultivated bacteria. The results obtained profoundly increased the understanding of these natural hot spots of greenhouse gas production/degradation and will help to enrich …

Utilization of microbial abundance and diversity as indicators of the origin of soil aggregates produced by earthworms

2013

This study aimed at testing the capability of microbial community structure and abundance to be used as bioindicators of the origin of earthworm cast aggregates. Compact surface casts produced by Amynthas khami and surrounding aggregates lacking visible signs of biological activity (control) were left to disaggregate by natural rainfall and separated into four size classes (5-2, 2-0.5, 0.5-0.25 and <0.25 mm). The genetic structure and the abundance of the bacterial and fungal communities were characterized using B- and F-ARISA fingerprinting approach and quantitative PCR directly from DNA extracted from soil. Bacteria and to a lesser extent fungi were more abundant in casts than in control …

2020

Microbial communities are continuously exposed to the arrival of alien species. In complex environments such as soil, the success of invasion depends on the characteristics of the habitat, especially the diversity and structure of the residing bacterial communities. While most data available on microbial invasion relies on experiments run under constant conditions, the fate of invading species when the habitat faces disturbances has not yet been addressed. Here, we designed experiments to assess the consequences of habitat disturbance on the success of ongoing microbial invasion. We investigated (i) if disturbance-induced alterations in resident microbial communities could mitigate or facil…

Fungemia due to Candida guilliermondii in a pediatric and adult population during a 12-year period.

2007

Candida guilliermondii fungemia is usually described in adults with hematologic malignancies, but in children, only 2 episodes have been published. From 1995 to 2006, 7 episodes (5 in children) were detected in our hospital. Molecular typing excluded a common infection source. C. guilliermondii fungemia may occur in children with underlying conditions other than cancer.

Bioprospecting the solar panel microbiome: High-throughput screening for antioxidant bacteria in a caenorhabditis elegansModel

2018

Microbial communities that are exposed to sunlight typically share a series of adaptations to deal with the radiation they are exposed to, including efficient DNA repair systems, pigment production and protection against oxidative stress, which makes these environments good candidates for the search of novel antioxidant microorganisms. In this research project, we isolated potential antioxidant pigmented bacteria from a dry and highly-irradiated extreme environment: solar panels. High-throughput in vivo assays using Caenorhabditis elegans as an experimental model demonstrated the high antioxidant and ultraviolet-protection properties of these bacterial isolates that proved to be rich in car…

Finding the missing link between diversity and activity using denitrifying bacteria as a model functional community

2005

The recent development and application of numerous methods mainly based on 16S rDNA analyses have brought insights into the questions of which and how many bacterial populations can be found in a given ecosystem. A new and challenging question for microbial ecologists has emerged from the exploration of this diversity: what is its significance for ecosystem functioning? We propose the denitrifying bacteria as a model microbial community for understanding the relationship between community structure and activity, and have summarized the recent progress in studies of this functional community.

Origin and phylogeography of the Chagas disease main vector Triatoma infestans based on nuclear rDNA sequences and genome size

2004

For about half of all Chagas disease cases T. infestans has been the responsible vector. Contributing to its genetic knowledge will increase Our understanding of the capacity of geographic expansion and domiciliation of triatomines. Populations of all infestans subcomplex species, T. infestans, T. delpontei, T. platensis and T. melanosoma and the so-called T. infestans "dark morph", from many South American countries were studied. A total of 10 and 7 different ITS-2 and ITS-1 haplotypes, respectively, were found. The total intraspecific ITS-2 nucleotide variability detected in T. infestans is the highest hitherto known in triatomines. ITS-1 minisatellites, detected for the first time in tri…

Genetic structure of Triatoma venosa (Hemiptera: Reduviidae): molecular and morphometric evidence.

2006

Triatoma venosa presents a restricted geographical distribution in America and is considered as a secondary vector of Chagas disease in Colombia and Ecuador. A total of 120 adult insects were collected in domestic and peridomestic habitats in an endemic area of the department of Boyaca, Colombia, in order to determine their genetic structure through morphometric and molecular techniques. The head and wings of each specimen were used for the analyses of size, shape, and sexual dimorphism. A significant sexual dimorphism was found, although no differences in size among the studied groups were detected. Differences were found in the analyzed structures except for male heads. DNA was extracted …

r- and K-selection in experimental populations of vesicular stomatitis virus.

2002

Here we explore the adaptation of vesicular stomatitis RNA virus to different population densities and the existence of a trade-off between r- and K-selection. Increasing population density represents a challenging special situation for viruses, since different selective pressures arise depending upon the number of available host cells per virus. Adaptation to low density represents a prototypical case of r-selection, where the optimal evolutionary solution should be a high replication rate. Adaptation to high density represents a case of K-selection. In this case, genotypes optimally exploiting the resources, instead of faster replicating ones, should be selected. Five independent populati…