196,075 research outputs found
Microbial symbiosis and the control of vector-borne pathogens in tsetse flies, human lice, and triatomine bugs
No full textSymbiosis is a widespread biological phenomenon, and is particularly common in arthropods. Bloodsucking insects are among the organisms that rely on beneficial bacterial symbionts to complement their unbalanced diet. This review is focused on describing symbiosis, and possible strategies for the symbiont-based control of insects and insect-borne diseases, in three bloodsucking insects of medical importance: the flies of the genus Glossina, the lice of the genus Pediculus, and triatomine bugs of the subfamily Triatominae. Glossina flies are vector of Trypanosoma brucei, the causative agent of sleeping sickness and other pathologies. They are also associated with two distinct bacterial symbionts, the primary symbiont Wigglesworthia spp., and the secondary, culturable symbiont Sodalis glossinidius. The primary symbiont of human lice, Riesia pediculicola, has been shown to be fundamental for the host, due to its capacity to synthesize B-group vitamins. An antisymbiotic approach, with antibiotic treatment targeted on the lice symbionts, could represent an alternative strategy to control these ectoparasites. In the case of triatominae bugs, the genetic modification of their symbiotic Rhodococcus bacteria, for production of anti- Trypanosoma molecules, is an example of paratransgenesis, i.e. the use of symbiotic microorganism engineered in order to reduce the vector competence of the insect host
Generalità sulle simbiosi in parassiti e in artropodi vettori, con alcuni riferimenti alle applicazioni in campo medico-veterinario
No full textInvestigation over the life cycle of ST1-C the endosymbiont of Scaphoideus titanus
No full textScaphoideus titanus Ball (Hemiptera Cicadellidae) is a phloem-feeder leafhopper vector of ‘Candidatus Phytoplasma vitis’, the
phytoplasma responsible of “flavescence dorée” (FD), a grape yellows afflicting several wine production areas in Europe. Natural
symbionts of the leafhopper for symbiotic control of FD transmission could be used. Previous work showed the presence of a
CFB bacterium, ‘Candidatus Cardinium sp.’ (named ST1-C) in several body districts of S. titanus. Our work was aimed to investigate
the life cycle of ST1-C endosymbiont inside and outside of insect body. We fed S. titanus individuals on artificial media
and tested insects and diets after the treatment for the presence of the ST1-C endosymbiont by qualitative and quantitative PCR,
showing the release of the bacterium during feeding. We also performed fluorescent in situ hybridization on the sugar solutions
after insect feeding, detecting ST1-C cells that confirmed its release into the medium. We tested by ST1-C-specific PCR DNA
extracted from small areas of grape leaves exposed to S. titanus, identifying the bacterium in the majority of pierced leaves. Our
experiments suggest that the ST1-C endosymbiont can undergo a horizontal transmission and have a complex life cycle possibly
involving more than one host
Do organic, conventional, and intensive approaches in livestock farming have an impact on the circulation of infectious agents and antimicrobial resistance? A systematic review, focused on dairy cattle
No full textIntroduction: A common thought is that extensive and organic breeding systems are associated with lower prevalence of infections in livestock animals, compared to intensive ones. In addition, organic systems limit the use of anti-microbial drugs, which may lead to lower emergence of antimicrobial resistances (AMR). Methods: To examine these issues, avoiding any a priori bias, we carried out a systematic literature search on dairy cattle breeding. Search was targeted to publications that compared different types of livestock farming (intensive, extensive, conventional, organic) in terms of the circulation of infectious diseases and AMR. Results and discussion: A total of 101 papers were finally selected. These papers did not show any trend in the circulation of the infections in the four types of breeding systems. However, AMR was more prevalent on conventional dairy farms compared to organic ones. The prevalence of specific pathogens and types of resistances were frequently associated with specific risk factors that were not strictly related to the type of farming system. In conclusion, we did not find any evidence suggesting that extensive and organic dairy farming bears any advantage over the intensive and conventional ones, in terms of the circulation of infectious agents
Ultrastructure of a novel Cardinium sp. symbiont in Scaphoideus titanus (Hemiptera: Cicadellidae)
No full textAn ultrastructural study of the novel symbiont Cardinium sp. was performed with particular attention to the description of the structure and organization of highly elaborated cytoplasmic complexes containing microtubule-like elements (MLC). Three major components were observed. The first was a system of microtubule-like elements (ML) arranged in parallel array extending from the plasma membrane into the cytosol of the bacterium. The second, an fibrous electrondense plaque (FEP), approximately 8 nm thick, located 7.5 nm away from the plasma membrane and parallel to it. The third component, not previously reported, was described for the first time in this paper. This consisted of a set of regularly distributed 8 nm electron-dense structures (ES), with a center-to-center spacing of about 12 nm, adhering to the outer leaflet of the plasma membrane. Often, the ES created a close connection between the plasma membrane and the outer membrane, so that in this area they became straight and stiff. The first and second component of these structures are compared to previously described microtubules and microfilaments
Presence of wolbachia in three hymenopteran species : diprion pini (Hymenoptera: Diprionidae), neodiprion sertifer (Hymenoptera: Diprionidae), and dahlbominus fuscipennis (Hymenoptera: Eulophidae)
No full textSawflies are important pests of various plant species. Diprion pini (L.) and Neodiprion sertifer (Geoffroy) (Hymenoptera: Diprionidae) are two of the most important sawfly pests in Italy, and both species are parasitized by the hymenopteran parasitoid Dahlbominus fuscipennis (Zetterstedt). Bacterial endosymbionts are currently studied for their high potential in strategies of biocontrol in a number of insect species. In this study, we investigated the presence of symbiotic bacteria (Wolbachia and Cardinium) in the three species of hymenoptera mentioned earlier, both in wild and laboratory populations. Although all samples were negative for the presence of Cardinium, 100% prevalence for Wolbachia was detected, as all examined individuals resulted to be PCR positive. Furthermore, 16S rDNA and ftsZ gene sequencing indicated that all individuals from the three hymenopteran species are infected by a single Wolbachia strain. Additionally, we report the presence of gynandromorphic individuals in D. pini, both in wild and laboratory-reared populations. Heat treatments on D. pini colonies removed the Wolbachia symbionts, but they also prevented the development of adults
Study of the bacterial community affiliated to Hyalesthes obsoletus, the insect vector of "bois noir" phytoplasma of grape
No full textGrape yellows caused by phytoplasmas afflict several important wine-producing areas of Europe. A grape yellows with increasing incidence in European vineyards is "bois noir" (BN), caused by 'Candidatus Phytoplasma solani'. Its vector is the planthopper Hyalesthes obsoletus Signoret (Hemiptera Cixiidae), occasionally feeding on grapevine. An innovative strategy for reducing the diffusion of the disease could be symbiotic control, exploiting the action of symbiotic microorganisms of the insect host. To investigate the occurrence of possible microbial candidates for symbiotic control we performed a molecular characterization of the bacteria associated to H. obsoletus. Length heterogeneity PCR was applied for a preliminary population screening. Taxonomic affiliations of the bacterial species were analyzed by denaturing gradient gel electrophoresis, showing, within the microbial diversity, the intracellular reproductive parasite Wolbachia pipientis and a Bacteroidetes symbiont with 92% nt identity with 'Candidatus Sulcia muelleri'. PCR essays specific for these bacteria showed they co-localize in several organs of H. obsoletus. Fluorescent in situ hybridization was performed to assess the distribution of these microorganisms within the insect body, showing interesting localization patterns, particularly in insect gonads and salivary glands. These results could be a starting point for a deeper investigation of functions and relationships between microbial species
Individuation and localization of "Candidatus Cardinium sp." endosymbiont in tissues and organs of Scaphoideus titanus, insect vector of Flavescence dorée in Vitis vinifera
No full textStudy of the bacterial community affiliated to Hyalesthes obsoletus, the insect vector of “bois noir” phytoplasma of grape
No full textGrape yellows caused by phytoplasmas afflict several important wine-producing areas of Europe. A grape yellows with increasingincidence in European vineyards is “bois noir” (BN), caused by ‘Candidatus Phytoplasma solani’. Its vector is the planthopperHyalesthes obsoletus Signoret (Hemiptera Cixiidae), occasionally feeding on grapevine. An innovative strategy for reducing thediffusion of the disease could be symbiotic control, exploiting the action of symbiotic microorganisms of the insect host. To investigatethe occurrence of possible microbial candidates for symbiotic control we performed a molecular characterization of thebacteria associated to H. obsoletus. Length heterogeneity PCR was applied for a preliminary population screening. Taxonomicaffiliations of the bacterial species were analyzed by denaturing gradient gel electrophoresis, showing, within the microbial diversity,the intracellular reproductive parasite Wolbachia pipientis and a Bacteroidetes symbiont with 92% nt identity with ‘CandidatusSulcia muelleri’. PCR essays specific for these bacteria showed they co-localize in several organs of H. obsoletus. Fluorescentin situ hybridization was performed to assess the distribution of these microorganisms within the insect body, showing interestinglocalization patterns, particularly in insect gonads and salivary glands. These results could be a starting point for a deeper investigationof functions and relationships between microbial species
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
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