Impact of mycolactone produced by Mycobacterium ulcerans on life-history traits of Aedes aegypti (L.) and resulting habitat selection for oviposition.

Buruli ulcer (BU) is a globally recognized, yet largely neglected tropical disease whose etiologic agent is Mycobacterium ulcerans. Although the exact mode of transmission is unclear, epidemiological evidence links BU incidence with slow-moving or stagnant, aquatic habitats, and laboratory-based experiments have shown disease manifestation in animals with dermal punctures. Therefore, hypotheses for transmission include contact with slowmoving aquatic habitats and associated biting aquatic insects, such as mosquitoes. Recent research demonstrated the toxin produced by M. ulcerans, mycolactone, is an attractant for adult mosquitoes seeking a blood-meal as well as oviposition sites. In the study presented here, we examined the impact of mycolactone at different concentrations on immature lifehistory traits of Aedes aegypti, which commonly occurs in the same environment as M. ulcerans. We determined percent egg hatch was not significantly different across treatments. However, concentration impacted the survivorship of larval mosquitoes to the adult stage (p < 0.001). Resulting adults also showed a slight preference, but not significant (p > 0.05), for oviposition in habitats contaminated with mycolactone suggesting a legacy effect.

Impact of mycolactone produced by Mycobacterium ulcerans on life-history traits of Aedes aegypti (L.) and resulting habitat selection for oviposition

@#Buruli ulcer (BU) is a globally recognized, yet largely neglected tropical disease whose etiologic agent is Mycobacterium ulcerans. Although the exact mode of transmission is unclear, epidemiological evidence links BU incidence with slow-moving or stagnant, aquatic habitats, and laboratory-based experiments have shown disease manifestation in animals with dermal punctures. Therefore, hypotheses for transmission include contact with slowmoving aquatic habitats and associated biting aquatic insects, such as mosquitoes. Recent research demonstrated the toxin produced by M. ulcerans, mycolactone, is an attractant for adult mosquitoes seeking a blood-meal as well as oviposition sites. In the study presented here, we examined the impact of mycolactone at different concentrations on immature lifehistory traits of Aedes aegypti, which commonly occurs in the same environment as M. ulcerans. We determined percent egg hatch was not significantly different across treatments. However, concentration impacted the survivorship of larval mosquitoes to the adult stage (p < 0.001). Resulting adults also showed a slight preference, but not significant (p > 0.05), for oviposition in habitats contaminated with mycolactone suggesting a legacy effect.

Mycobacterium ulcerans toxin, mycolactone may enhance host-seeking and oviposition behaviour by Aedes aegypti (L.) (Diptera: Culicidae).

The ecological functions of many toxins continue to remain unknown for those produced by environmental pathogens. Mycobacterium ulcerans, the causative agent of the neglected tropical disease, Buruli ulcer, produces a cytotoxic macrolide, mycolactone, whose function(s) in the environment remains elusive. Through a series of dual-choice behaviour assays, they show that mycolactone may be an interkingdom cue for the yellow fever mosquito, Aedes aegypti, seeking blood-meals as well as oviposition sites. Results provide novel insight into the evolution between bacteria and potential vectors. While further studies are needed to determine if mycolactone is an actual signal rather than simply a cue, this discovery could serve as a model for determining roles for toxins produced by other environmental pathogens and provide opportunities for developing novel strategies for disease prevention. The relationship between M. ulcerans, mycolactone, and Ae. aegypti further suggests there could be an amplification effect for the spread of pathogens responsible for other diseases, such as yellow fever and dengue.

Fluorescently labeled bacteria provide insight on post-mortem microbial transmigration.

Microbially mediated mechanisms of human decomposition begin immediately after death, and are a driving force for the conversion of a once living organism to a resource of energy and nutrients. Little is known about post-mortem microbiology in cadavers, particularly the community structure of microflora residing within the cadaver and the dynamics of these communities during decomposition. Recent work suggests these bacterial communities undergo taxa turnover and shifts in community composition throughout the post-mortem interval. In this paper we describe how the microbiome of a living host changes and transmigrates within the body after death thus linking the microbiome of a living individual to post-mortem microbiome changes. These differences in the human post-mortem from the ante-mortem microbiome have demonstrated promise as evidence in death investigations. We investigated the post-mortem structure and function dynamics of Staphylococcus aureus and Clostridium perfringens after intranasal inoculation in the animal model Mus musculus L. (mouse) to identify how transmigration of bacterial species can potentially aid in post-mortem interval estimations. S. aureus was tracked using in vivo and in vitro imaging to determine colonization routes associated with different physiological events of host decomposition, while C. perfringens was tracked using culture-based techniques. Samples were collected at discrete time intervals associated with various physiological events and host decomposition beginning at 1h and ending at 60 days post-mortem. Results suggest that S. aureus reaches its highest concentration at 5-7 days post-mortem then begins to rapidly decrease and is undetectable by culture on day 30. The ability to track these organisms as they move in to once considered sterile space may be useful for sampling during autopsy to aid in determining post-mortem interval range estimations, cause of death, and origins associated with the geographic location of human remains during death investigations.

A simplified method of echocardiographic data analysis.

Rapid accurate analysis of echocardiographic data is accomplished using a sonic digitizer and programmable calculator. This method allows the echocardiographer to select technically optimal areas of the recording for analysis. The resolution of the measuring device is 0.1 mm. A hardcopy printout of both measurement and calculation is provided. Instead of expensive on-line computer, an inexpensive programmable calculator is used.