Development of Onchocerca volvulus Larvae in Simulium pintoi in the Amazonas Region of Venezuela

The intake and development of Onchocerca volvulus in Simulium pintoi from the Parima mountain region of the Federal Territory of Amazonas in Venezuela, were studied experimentally. When wild females fed on the lower half of the legs and lower third of the back of an onchocerciasis patient harboring 23 and 264 microfilariae per skin snip, respectively, at each site, an average (median) of 14 (range, 1?77) and 245 (range, 58?495) microfilariae was ingested. However, within 24 hours of microfilarial ingestion a mortality of 47% (16/34 flies) was observed in the group of flies which fed on the back, as compared with 2% (2/101 flies) in the other group which fed on the legs. At a temperature varying between 16°C and 24°C, the development of O. volvulus larvae in S. pintoi was synchronous and orderly; no abnormal nor deformed larvae were observed. Third-stage larvae were first seen in the head of flies dying between 8 and 9 days after microfilarial ingestion, and 98 of 100 larvae recovered from days 10?16 were in the third stage. The proportions of females harboring third-stage larvae among flies which lived through day 8 in the two groups which fed on the legs and back, respectively, were 55% (21/38 flies) and 63% (5/8 flies). Although only two of five positive flies in the latter group contained third-stage larvae in the head (1 and 12, respectively), 71% (15/21 positive flies) of the former group had an average of 2.7 third-stage larvae in the head (range, 1?10). In conclusion, it is suggested that S. pintoi is an efficient vector of O. volvulus due to its high susceptibility, in spite of the high mortality caused by an excessive intake of microfilariae

From friends to foes: fungi could be emerging marine sponge pathogens under global change scenarios

Global change, experienced in the form of ocean warming and pollution by man-made goods and xenobiotics, is rapidly affecting reef ecosystems and could have devastating consequences for marine ecology. Due to their critical role in regulating marine food webs and trophic connections, sponges are an essential model for studying and forecasting the impact of global change on reef ecosystems. Microbes are regarded as major contributors to the health and survival of sponges in marine environments. While most culture-independent studies on sponge microbiome composition to date have focused on prokaryotic diversity, the importance of fungi in holobiont behavior has been largely overlooked. Studies focusing on the biology of sponge fungi are uncommon. Thus, our current understanding is quite limited regarding the interactions and “crosstalk” between sponges and their associated fungi. Anthropogenic activities and climate change may reveal sponge-associated fungi as novel emerging pathogens. Global change scenarios could trigger the expression of fungal virulence genes and unearth new opportunistic pathogens, posing a risk to the health of sponges and severely damaging reef ecosystems. Although ambitious, this hypothesis has not yet been proven. Here we also postulate as a pioneering hypothesis that manipulating sponge-associated fungal communities may be a new strategy to cope with the threats posed to sponge health by pathogens and pollutants. Additionally, we anticipate that sponge-derived fungi might be used as novel sponge health promoters and beneficial members of the resident sponge microbiome in order to increase the sponge's resistance to opportunistic fungal infections under a scenario of global change

Evaluación de Impactos sobre Salud Ambiental en la Amazonia

Versión en inglés disponible en la Biblioteca Digital del IDRC: Environmental health impact assessment in the Amazo

Environmental health impact assessment in the Amazon

Spanish version available in IDRC Digital Library: Evaluación de Impactos sobre Salud Ambiental en la Amazoni

Diversity of culturable bacteria recovered from Pico Bolívar’s glacial and subglacial environments,at 4950 m,in Venezuelan tropical Andes

Even though tropical glaciers are retreating rapidly and many will disappear in the next few years,their microbial diversity remains to be studied in depth. In this paper we report on the biodiversity of the culturable fraction of bacteria colonizing Pico Bolívar’s glacier ice and subglacial meltwaters,at ~4950 m in the Venezuelan Andean Mountains. Microbial cells of diverse morphologies and exhibiting uncompromised membranes were present at densities ranging from 1.5 × 104 to 4.7 × 104 cells/mL in glacier ice and from 4.1 × 105 to 9.6 × 105 cells/mL in subglacial meltwater. Of 89 pure isolates recovered from the samples,the majority were eurypsychrophilic or stenopsychrophilic,according to their temperature range of growth. Following analysis of their 16S rDNA nucleotidic sequence,54 pure isolates were assigned to 23 phylotypes distributed within 4 different phyla or classes: Beta- and Gammaproteobacteria,Actinobacteria,and Bacteroidetes. Actinobacteria dominated the culturable fraction of glacier ice samples,whereas Proteobacteria were dominant in subglacial meltwater samples. Chloramphenicol and ampicillin resistance was exhibited by 73.07% and 65.38%,respectively,of the subglacial isolates,and nearly 35% of them were multiresistant. Considering the fast rate at which tropical glaciers are melting,this study confirms the urgent need to study the microbial communities immured in such environments

Etude de l'opéron rus, codant pour sept protéines transporteurs d'électrons, chez la bactérie acidophile, chimioautotrophe obligatoire, Acidithiobacillus ferrooxidans

AIX-MARSEILLE2-BU Sci.Luminy (130552106) / SudocSudocFranceF

Microbial-based technologies for improving smallholder agriculture in the Ecuadorian Andes: current situation, challenges, and prospects

As in other Andean countries, smallholder agriculture is the base that supports food and nutrient security in Ecuador. Ironically, in spite of their importance, the development of context-appropriate technologies for these farming systems remains still at its infancy. Today, most smallholders in the Ecuadorian Andes practice a type of hybrid agriculture that merges traditional local practices and modern technologies. This mixture of traditional and “modern” conventional technologies does not always result in resource-efficient sustainable practices. Although they represent only part of a global solution, microbial-based technologies offer a great potential to improve the functioning of smallholder farms in the Ecuadorian Andes. From nutrient cycling to biocontrol and plant growth promotion, microbial technology applications match existing needs for technology development in these systems; however, as in many cases, knowledge gaps and context-adapted implementation are some of the challenges that slow down the spreading and efficient use of these technologies. Here we offer a review of the efforts made as of today to characterize, develop and test microbial-based technologies that could boost smallholder Andean agriculture with a particular focus in the Ecuadorian context. We also propose potential lines of action to increase or accelerate the impact of these technologies

Antarctic pseudomonas spp. promote wheat germination and growth at low temperatures

The development of cold-active biofertilizers and biopesticides could help improve sustainable agriculture in mountainous regions. With this aim, both psychrophilic and psychrotolerant microorganisms have been prospected in cold regions around the world and tested for their plant-growth promoting (PGP) effects. Interestingly, very little is known about the PGP effects of polar microorganisms in commercial crops. This study aimed at isolating cold-active plant-growth promoting Pseudomonas spp. from Antarctic soils and testing their PGP effects, both in vitro and on wheat (Triticum aestivum). Twenty-five Pseudomonas spp. strains isolated from Antarctic soils at Greenwich Island (South Shetland Islands, Antarctic Peninsula) were tested. The isolates grew well at temperatures ranging from 4 to 30 °C and were therefore considered as eury-psychrophiles. The isolates solubilized tri-calcium phosphate at 8 and 16 °C in the presence of different sugars as sole carbon sources. Besides producing indole-acetic acid, siderophores and hydrogen cyanide, several isolates inhibited growth of three plant pathogenic fungi (Fusarium oxysporum, Pythium ultimum and Phytophtora infestans) by means of both soluble- and volatile-secondary metabolites. Bacterization of T. aestivum seeds with selected isolates significantly enhanced root elongation. Moreover, when grown in sterile soil and in a temperature-controlled growth chamber at 14 ± 1 °C, inoculated T. aestivum seedlings showed a significant increase in their root- and shoot-lengths compared to untreated controls. Overall, the results suggest that some of these Antarctic Pseudomonas spp. isolates could act as cold-active biofertilizers