Wolbachia Symbiont Infections Induce Strong Cytoplasmic Incompatibility in the Tsetse Fly Glossina morsitans

Tsetse flies are vectors of the protozoan parasite African trypanosomes, which cause sleeping sickness disease in humans and nagana in livestock. Although there are no effective vaccines and efficacious drugs against this parasite, vector reduction methods have been successful in curbing the disease, especially for nagana. Potential vector control methods that do not involve use of chemicals is a genetic modification approach where flies engineered to be parasite resistant are allowed to replace their susceptible natural counterparts, and Sterile Insect technique (SIT) where males sterilized by chemical means are released to suppress female fecundity. The success of genetic modification approaches requires identification of strong drive systems to spread the desirable traits and the efficacy of SIT can be enhanced by identification of natural mating incompatibility. One such drive mechanism results from the cytoplasmic incompatibility (CI) phenomenon induced by the symbiont Wolbachia. CI can also be used to induce natural mating incompatibility between release males and natural populations. Although Wolbachia infections have been reported in tsetse, it has been a challenge to understand their functional biology as attempts to cure tsetse of Wolbachia infections by antibiotic treatment damages the obligate mutualistic symbiont (Wigglesworthia), without which the flies are sterile. Here, we developed aposymbiotic (symbiont-free) and fertile tsetse lines by dietary provisioning of tetracycline supplemented blood meals with yeast extract, which rescues Wigglesworthia-induced sterility. Our results reveal that Wolbachia infections confer strong CI during embryogenesis in Wolbachia-free (GmmApo) females when mated with Wolbachia-infected (GmmWt) males. These results are the first demonstration of the biological significance of Wolbachia infections in tsetse. Furthermore, when incorporated into a mathematical model, our results confirm that Wolbachia can be used successfully as a gene driver. This lays the foundation for new disease control methods including a population replacement approach with parasite resistant flies. Alternatively, the availability of males that are reproductively incompatible with natural populations can enhance the efficacy of the ongoing sterile insect technique (SIT) applications by eliminating the need for chemical irradiation

Gene expression level influences amino acid usage, but not codon usage, in the tsetse fly endosymbiont Wigglesworthia

Author Posting. © Society for General Mircobiology, 2003. This article is posted here by permission of Society for General Mircobiology for personal use, not for redistribution. The definitive version was published in Microbiology 149 (2003): 2585-2596, doi:10.1099/mic.0.26381-0.Wigglesworthia glossinidia brevipalpis, the obligate bacterial endosymbiont of the tsetse fly Glossina brevipalpis, is characterized by extreme genome reduction and AT nucleotide composition bias. Here, multivariate statistical analyses are used to test the hypothesis that mutational bias and genetic drift shape synonymous codon usage and amino acid usage of Wigglesworthia. The results show that synonymous codon usage patterns vary little across the genome and do not distinguish genes of putative high and low expression levels, thus indicating a lack of translational selection. Extreme AT composition bias across the genome also drives relative amino acid usage, but predicted high-expression genes (ribosomal proteins and chaperonins) use GC-rich amino acids more frequently than do low-expression genes. The levels and configuration of amino acid differences between Wigglesworthia and Escherichia coli were compared to test the hypothesis that the relatively GC-rich amino acid profiles of high-expression genes reflect greater amino acid conservation at these loci. This hypothesis is supported by reduced levels of protein divergence at predicted high-expression Wigglesworthia genes and similar configurations of amino acid changes across expression categories. Combined, the results suggest that codon and amino acid usage in the Wigglesworthia genome reflect a strong AT mutational bias and elevated levels of genetic drift, consistent with expected effects of an endosymbiotic lifestyle and repeated population bottlenecks. However, these impacts of mutation and drift are apparently attenuated by selection on amino acid composition at high-expression genes.This work was made possible by support to J. J. W. from the NIH (R01 GM62626-01) and NSF (DEB 0089455), and the Josephine Bay Paul and C. Michael Paul Foundation

Insight into the Transmission Biology and Species-Specific Functional Capabilities of Tsetse (Diptera: Glossinidae) Obligate Symbiont Wigglesworthia

Ancient endosymbionts have been associated with extreme genome structural stability with little differentiation in gene inventory between sister species. Tsetse flies (Diptera: Glossinidae) harbor an obligate endosymbiont, Wigglesworthia, which has coevolved with the Glossina radiation. We report on the ~720-kb Wigglesworthia genome and its associated plasmid from Glossina morsitans morsitans and compare them to those of the symbiont from Glossina brevipalpis. While there was overall high synteny between the two genomes, a large inversion was noted. Furthermore, symbiont transcriptional analyses demonstrated host tissue and development-specific gene expression supporting robust transcriptional regulation in Wigglesworthia, an unprecedented observation in other obligate mutualist endosymbionts. Expression and immunohistochemistry confirmed the role of flagella during the vertical transmission process from mother to intrauterine progeny. The expression of nutrient provisioning genes (thiC and hemH) suggests that Wigglesworthia may function in dietary supplementation tailored toward host development. Furthermore, despite extensive conservation, unique genes were identified within both symbiont genomes that may result in distinct metabolomes impacting host physiology. One of these differences involves the chorismate, phenylalanine, and folate biosynthetic pathways, which are uniquely present in Wigglesworthia morsitans. Interestingly, African trypanosomes are auxotrophs for phenylalanine and folate and salvage both exogenously. It is possible that W. morsitans contributes to the higher parasite susceptibility of its host species

Phylogenomics of Reichenowia parasitica, an Alphaproteobacterial Endosymbiont of the Freshwater Leech Placobdella parasitica

Although several commensal alphaproteobacteria form close relationships with plant hosts where they aid in (e.g.,) nitrogen fixation and nodulation, only a few inhabit animal hosts. Among these, Reichenowia picta, R. ornata and R. parasitica, are currently the only known mutualistic, alphaproteobacterial endosymbionts to inhabit leeches. These bacteria are harbored in the epithelial cells of the mycetomal structures of their freshwater leech hosts, Placobdella spp., and these structures have no other obvious function than housing bacterial symbionts. However, the function of the bacterial symbionts has remained unclear. Here, we focused both on exploring the genomic makeup of R. parasitica and on performing a robust phylogenetic analysis, based on more data than previous hypotheses, to test its position among related bacteria. We sequenced a combined pool of host and symbiont DNA from 36 pairs of mycetomes and performed an in silico separation of the different DNA pools through subtractive scaffolding. The bacterial contigs were compared to 50 annotated bacterial genomes and the genome of the freshwater leech Helobdella robusta using a BLASTn protocol. Further, amino acid sequences inferred from the contigs were used as queries against the 50 bacterial genomes to establish orthology. A total of 358 orthologous genes were used for the phylogenetic analyses. In part, results suggest that R. parasitica possesses genes coding for proteins related to nitrogen fixation, iron/vitamin B translocation and plasmid survival. Our results also indicate that R. parasitica interacts with its host in part by transmembrane signaling and that several of its genes show orthology across Rhizobiaceae. The phylogenetic analyses support the nesting of R. parasitica within the Rhizobiaceae, as sister to a group containing Agrobacterium and Rhizobium species

Nutritional upgrading for omnivorous carpenter ants by the endosymbiont Blochmannia

<p>Abstract</p> <p>Background</p> <p>Carpenter ants (genus <it>Camponotus</it>) are considered to be omnivores. Nonetheless, the genome sequence of <it>Blochmannia floridanus</it>, the obligate intracellular endosymbiont of <it>Camponotus floridanus</it>, suggests a function in nutritional upgrading of host resources by the bacterium. Thus, the strongly reduced genome of the endosymbiont retains genes for all subunits of a functional urease, as well as those for biosynthetic pathways for all but one (arginine) of the amino acids essential to the host.</p> <p>Results</p> <p>Nutritional upgrading by <it>Blochmannia </it>was tested in 90-day feeding experiments with brood-raising in worker-groups on chemically defined diets with and without essential amino acids and treated or not with antibiotics. Control groups were fed with cockroaches, honey water and Bhatkar agar. Worker-groups were provided with brood collected from the queenright mother-colonies (45 eggs and 45 first instar larvae each). Brood production did not differ significantly between groups of symbiotic workers on diets with and without essential amino acids. However, aposymbiotic worker groups raised significantly less brood on a diet lacking essential amino acids. Reduced brood production by aposymbiotic workers was compensated when those groups were provided with essential amino acids in their diet. Decrease of endosymbionts due to treatment with antibiotic was monitored by qRT-PCR and FISH after the 90-day experimental period. Urease function was confirmed by feeding experiments using ¹⁵N-labelled urea. GC-MS analysis of ¹⁵N-enrichment of free amino acids in workers revealed significant labelling of the non-essential amino acids alanine, glycine, aspartic acid, and glutamic acid, as well as of the essential amino acids methionine and phenylalanine.</p> <p>Conclusion</p> <p>Our results show that endosymbiotic <it>Blochmannia </it>nutritionally upgrade the diet of <it>C. floridanus </it>hosts to provide essential amino acids, and that it may also play a role in nitrogen recycling via its functional urease. <it>Blochmannia </it>may confer a significant fitness advantage via nutritional upgrading by enhancing competitive ability of <it>Camponotus </it>with other ant species lacking such an endosymbiont. Domestication of the endosymbiont may have facilitated the evolutionary success of the genus <it>Camponotus</it>.</p

Tsetse Immune System Maturation Requires the Presence of Obligate Symbionts in Larvae

Tsetse harbors an obligate symbiont, Wigglesworthia glossinidia, that must be present during larval maturation for the fly's immune system to develop and function properly during adulthood

Ornithologische Beobachtungen im afghanischen Pamir

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An integrated software architecture for rapid product development processes

In the complex process of product development, the ongoing distribution of processes and globalization of markets force companies to implement means of cooperation between partners at remote sites and coordination of tasks. In this paper we describe a distributed software architecture which provides an integrated set of tools for a wide range of Rapid Product Development processes. The central component is an active knowledge base called ASN (Active Semantic Network) which is used as shared data repository and team process coordination and upon which the other components of the system operate. The scenarios described are coming from the car manufacturing area ranging from collaborative development of simulation prototypes using supercomputers to virtual reality analysis techniques