An ex vivo system for investigation of Plasmodium berghei invasion of the salivary gland of Anopheles stephensi mosquitoes

Plasmodium sporozoites associated with the midgut and in the hemolymph of mosquitoes differ from sporozoites in the secretory cavities and ducts of the insects' salivary glands in their transcriptome, proteome, motility, and infectivity. Using an ex vivo Anopheles stephensi salivary gland culture system incorporating simple microfluidics and transgenic Plasmodium berghei with the fluorescent protein gene mCherry under the transcriptional control of the Pbuis4 promoter whose expression served as a proxy for parasite maturation, we observed rapid parasite maturation in the absence of salivary gland invasion. While in vivo Pbuis4::mCherry expression was only detectable in sporozoites within the salivary glands (mature parasites) as expected, the simple exposure of P. berghei sporozoites to dissected salivary glands led to rapid parasite maturation as indicated by mCherry expression. These results suggest that previous efforts to develop ex vivo and in vitro systems for investigating sporozoite interactions with mosquito salivary glands have likely been unsuccessful in part because the maturation of sporozoites leads to a loss in the ability to invade salivary glands.

A Cross-Sectional Survey of Biosafety Professionals Regarding Genetically Modified Insects

BACKGROUND

Genetic technologies such as gene editing and gene drive create challenges for existing frameworks used to assess risk and make regulatory determinations by governments and institutions. Insect genetic technologies including transgenics, gene editing, and gene drive may be particularly challenging because of the large and increasing number of insect species being genetically modified and the degree of familiarity with these organisms and technologies by biosafety officials charged with making containment decisions.

METHODS

An anonymous online survey of biosafety professionals was distributed to the membership of ABSA International, a global society of biosafety professionals, to investigate their perspectives on their preparedness to meet these new challenges.

RESULTS

Existing guidance used to make containment decisions for nongenetically modified insects was widely seen as adequate, and most respondents thought the available guidance for making containment decisions for genetically modified insects with and without gene drives was inadequate. Most respondents reported having less confidence in their decisions concerning containment of genetically modified insects compared to decisions involving genetically modified microbes, (noninsect) animals, and plants.

CONCLUSIONS

These results reveal a need for additional support for biosafety professionals to improve the quality of and confidence in containment decisions regarding genetically modified insects with and without gene drive. These needs might be addressed by increasing training, updating existing guidance, creating new guidance, and creating a third-party accreditation entity to support institutions. Sixty percent of the respondents said they either would or might use a voluntary third-party accreditation service to support insect containment decisions.

O’brochta D. Microinjection protocol for Spodoptera Sp. v1.. [DOI: 10.17504/protocols.io.marc2d6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Modification on the coventional protocol for insect microinjection was performed. This protocol describe a simple and unique protocol for microinjecting Spodoptera frugiperda. Insect eggs with thin chorions such as S. frugiperda or with chorions that are removable can be sensitive to desiccation, resulting in death of the embyro. To control or prevent excessive desiccation, eggs can be covered with liquid during the microinjection process. Spodoptera frugiperda are relatively large insect eggs (about 400μm in diameter) and because the chorion does not have to be removed it is somewhat less sensitive to desiccation during the microinjection process. However, injecting S. frugiperda eggs in the absence of any fluid covering resulted in rapid clogging of injection needles due to rapid drying of residual ooplasm onto the outside of the needle. So, seek for alternative covering liquid became a demand to overcome the lethal effect of the conventional covering liquid in order to developed microinjection and delivering system for the target insect emberyo. New liquids were tested for their compatibility with S. frugiperda viability. Halocarbon oils (either low viscosity #27 or high viscosity #700) which are used routinely during the microinjection of some Diptera, allowed for easy injections but were lethal to S. frugiperda embryos even after removing as much of the residual oil as possible immediately following injection. Alternatively, an emulsion of halocarbon oil and water; polysorbate 20 (Tween 20®); was used and didn’t affect on egg viability (90% hatch rate), while it causes turbidity and made injections more difficult due to the obstructed visibility. Finally, dilution of honey was found to a very effective medium with which to temporarily cover the eggs during injection resulting in a 100% survival rate of properly aged embryos. The solutions viscosity was similar to halocarbon oil #27 and this allowed the honey solution to completely cover the eggs without flowing off of the eggs and onto the glass slide. There were no problems with injection needles clogging due to ooplasm adhering and drying on the outside of the needle, and the honey solution was readily removed immediately after injection. Prolonged (24hrs or longer) exposure of developing embryos to the honey solution was detrimental to embryonic development and led eventually to death of the embryos before hatching and therefore it was removed immediately after eggs were injected.

O’brochta D. Microinjection protocol for Spodoptera Sp. v3.. [DOI: 10.17504/protocols.io.manc2de] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Modification on the coventional protocol for insect microinjection was performed. This protocol describe a simple and unique protocol for microinjecting Spodoptera frugiperda. Insect eggs with thin chorions such as S. frugiperda or with chorions that are removable can be sensitive to desiccation, resulting in death of the embyro. To control or prevent excessive desiccation, eggs can be covered with liquid during the microinjection process. Spodoptera frugiperda are relatively large insect eggs (about 400μm in diameter) and because the chorion does not have to be removed it is somewhat less sensitive to desiccation during the microinjection process. However, injecting S. frugiperda eggs in the absence of any fluid covering resulted in rapid clogging of injection needles due to rapid drying of residual ooplasm onto the outside of the needle. So, seek for alternative covering liquid became a demand to overcome the lethal effect of the conventional covering liquid in order to developed microinjection and delivering system for the target insect emberyo. New liquids were tested for their compatibility with S. frugiperda viability. Halocarbon oils (either low viscosity #27 or high viscosity #700) which are used routinely during the microinjection of some Diptera, allowed for easy injections but were lethal to S. frugiperda embryos even after removing as much of the residual oil as possible immediately following injection. Alternatively, an emulsion of halocarbon oil and water; polysorbate 20 (Tween 20®); was used and didn’t affect on egg viability (90% hatch rate), while it causes turbidity and made injections more difficult due to the obstructed visibility. Finally, dilution of honey was found to a very effective medium with which to temporarily cover the eggs during injection resulting in a 100% survival rate of properly aged embryos. The solutions viscosity was similar to halocarbon oil #27 and this allowed the honey solution to completely cover the eggs without flowing off of the eggs and onto the glass slide. There were no problems with injection needles clogging due to ooplasm adhering and drying on the outside of the needle, and the honey solution was readily removed immediately after injection. Prolonged (24hrs or longer) exposure of developing embryos to the honey solution was detrimental to embryonic development and led eventually to death of the embryos before hatching and therefore it was removed immediately after eggs were injected.

O’brochta D. Microinjection protocol for Spodoptera Sp. v4.. [DOI: 10.17504/protocols.io.maqc2dw] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Modification on the coventional protocol for insect microinjection was performed. This protocol describe a simple and unique protocol for microinjecting Spodoptera frugiperda. Insect eggs with thin chorions such as S. frugiperda or with chorions that are removable can be sensitive to desiccation, resulting in death of the embyro. To control or prevent excessive desiccation, eggs can be covered with liquid during the microinjection process. Spodoptera frugiperda are relatively large insect eggs (about 400μm in diameter) and because the chorion does not have to be removed it is somewhat less sensitive to desiccation during the microinjection process. However, injecting S. frugiperda eggs in the absence of any fluid covering resulted in rapid clogging of injection needles due to rapid drying of residual ooplasm onto the outside of the needle. So, seek for alternative covering liquid became a demand to overcome the lethal effect of the conventional covering liquid in order to developed microinjection and delivering system for the target insect emberyo. New liquids were tested for their compatibility with S. frugiperda viability. Halocarbon oils (either low viscosity #27 or high viscosity #700) which are used routinely during the microinjection of some Diptera, allowed for easy injections but were lethal to S. frugiperda embryos even after removing as much of the residual oil as possible immediately following injection. Alternatively, an emulsion of halocarbon oil and water; polysorbate 20 (Tween 20®); was used and didn’t affect on egg viability (90% hatch rate), while it causes turbidity and made injections more difficult due to the obstructed visibility. Finally, dilution of honey was found to a very effective medium with which to temporarily cover the eggs during injection resulting in a 100% survival rate of properly aged embryos. The solutions viscosity was similar to halocarbon oil #27 and this allowed the honey solution to completely cover the eggs without flowing off of the eggs and onto the glass slide. There were no problems with injection needles clogging due to ooplasm adhering and drying on the outside of the needle, and the honey solution was readily removed immediately after injection. Prolonged (24hrs or longer) exposure of developing embryos to the honey solution was detrimental to embryonic development and led eventually to death of the embryos before hatching and therefore it was removed immediately after eggs were injected.

Post-integration silencing of piggyBac transposable elements in Aedes aegypti

The piggyBac transposon, originating in the genome of the Lepidoptera Trichoplusia ni, has a broad host range, making it useful for the development of a number of transposon-based functional genomic technologies including gene vectors, enhancer-, gene- and protein-traps. While capable of being used as a vector for the creation of transgenic insects and insect cell lines, piggyBac has very limited mobility once integrated into the genome of the yellow fever mosquito, Aedes aegypti. A transgenic Aedes aegypti cell line (AagPB8) was created containing three integrated piggyBac elements and the remobilization potential of the elements was tested. The integrated piggyBac elements in AagPB8 were transpositionally silent in the presence of functional transposase, which was shown to be capable of catalyzing the movement of plasmid-borne piggyBac elements in the same cells. The structural integrity of one of the integrated elements along with the quality of element-flanking DNA, which is known to influence transposition rates, were tested in D. melanogaster. The element was found to be structurally intact, capable of transposition and excision in the soma and germ-line of Drosophila melanogaster, and in a DNA sequence context highly conducive to element movement in Drosophila melanogaster. These data show that transpositional silencing of integrated piggyBac elements in the genome of Aedes aegypti appears to be a function of higher scale genome organization or perhaps epigenetic factors, and not due to structural defects or suboptimal integration sites.