No abstract

Crop wild relatives that have experienced multiple and independent domestication events provide an excellent model for understanding adaptation processes in crop populations and a first and relevant aspect to investigate is the geographic origin of landraces. The aim of this research was to establish the origin of Mesoamerican and Andean Lima bean (Phaseolus lunatus L.) landraces by analyzing chloroplast DNA and ITS polymorphisms in a sample of 59 wild and 50 landrace accessions. According to seed size, genetic distance analyses, and haplotype networks, at least two independent domestication events are proposed. The first one would have taken place in the Andes of southern Ecuador–northwestern Peru and would have given rise to the large‐seeded landraces collectively known as the “Big Lima” cultivars. The second one would have taken place in central–western Mexico, more likely in the area to the north and northwest of the Isthmus of Tehuantepec. This event, along with post‐domestication migrations of landraces in South America, would have given rise to the great variety of small‐seeded Mesoamerican landraces that exist today. We did not find any evidence supporting the existence of two discrete groups within Mesoamerican landraces that might correspond to the previously proposed “Sieva” and “Potato” cultigroups. A severe reduction in genetic diversity because of domestication, known as the “founder effect”, was detected, which may have implications for the conservation of genetic resources in this species.

The prokaryotic community at the "La Cira-Infantas" oil field, located in Colombia's Middle Magdalena Valley Basin, was characterized using 16S rRNA gene sequence analysis. This characterization is a first-step in assessing the dynamics of microbial degradation and defining strategies that may increase oil recovery and quality at the site. Two 16S rRNA gene libraries were generated from the total community DNA extracted from production water using both Eubacterial and Archaea universal primers. Sequence analysis of the libraries indicated that a large percentage of Eubacteria clones were affiliated with class -, -and -Proteobacteria, Clostridia and Bacteroidetes. Archaea clones were dominated by Methanobacteria andMethanococci. Annotations at these generic level indicate that the prokaryotic community has the following metabolic capacities: i) reduction of sulfur-compounds and fermentation, ii) nitrate reduction and sulfide oxidation, iii) decomposition of aromatic compounds, and iv) methane production. These results are discussed in the context of the importance of the characterized metabolic capacities for oil biodegradation in the mesothermic and water-flooded environment of this reservoir. Geomicrobiology Journal ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT3

Chagas disease is a severe public health problem in Latin-American countries. In Colombia, the predominance of Trypanosoma cruzi I has been described in the literature, with a broad heterogeneity between strains. However, most of the studies carried out centered on isoenzyme analysis, with a smaller number that focus on other molecular methods. In this report, we discuss the results of a molecular analysis of T. cruzi I strains, isolated from the domestic cycle, from the department of Santander, one of the territorial divisions where the prevalence of infection is highest. Internal transcribed spacer-restriction fragment length polymorphism and random amplification of polymorphic DNA were used to characterize 16 strains from human and vector (Triatominae) hosts. The data reveal a clustering based on the biological origin. Human and vector strains grouped separately; however, three vector strains clustered together with human strains. These results indicate that genetic differences exist in the strains that infect both hosts. We conclude that T. cruzi I populations in the domestic cycle of transmission of Chagas disease in Santander are heterogeneous and are composed of different clones. The epidemiological and biological implications are discussed.

One hundred twenty Rhodnius prolixus (Stal) (Hemiptera: Reduviidae) specimens from 6 Colombian Departments and 1 Venezuelan State had 594-bp of the mitochondrial cytochrome-b gene sequenced to improve the understanding of evolutionary processes that shape the main vector of Chagas disease. The levels of genetic diversity for this species were low-medium with reference to other bugs. The genetic heterogeneity among the populations was very limited which means there has been extensive gene flow and/or very recent split processes. The overall sample as well as some individual populations showed evidence of recent population expansions (with the exception of Arauca, which yielded evidence of a bottleneck for a mismatch distribution). This expansion (11,000 or 2000-25,000 year ago depending of two procedures employed) coincides with the ending of the last intense glacial conditions during the Pleistocene and the beginning of the Holocene that had a warmer and wetter climate. Some of our autocorrelation analyses (AIDA and Genetic Landscape Interpolation Analysis) indicated local patches of high genetic similarity but no globally significant spatial structure. We did show an original haplotype distributed throughout the entirety of the geographical area studied.