Transgenic Effectors for Neurogenic Manipulation

Genetic technologies will continue to play an increasingly important role in enabling the function of specific neurons in insect behavior to be determined.

Larval brain of Drosophila melanogaster. from Atlas of Drosophila Development by Volker Hartenstein

Larval brain of Drosophila melanogaster.
from Atlas of Drosophila Development by Volker Hartenstein

The genetic technologies available for manipulating Drosophila melanogaster provides not only great examples but some of these technologies might also be resources for those working on other insects. With the increasing technical capabilities of those studying other insect systems, it is possible to imagine some of these advanced technologies being adopted for use in other insect systems.

Pauls et al. (2014) describe their efforts to compare “transgenic effectors” (transgenes that affect in various ways the cells in which they are expressed) on their ability to manipulate neurons in Drosophila larvae.

Pauls et al. (2014) is a nice compilation of information on various genetic strategies for manipulating neurons in Drosophila. They use certain larval behaviors as paradigms and are able to quantitatively compare the effects of using various genetic strategies to, kill/ablate specific neurons, silence neuronal activity and increase neuronal excitability on specific behaviors.

Example of UAS/Gal4 in larval brain of D. melanogaster.  CCAP-Gal4 (Crustacean Cardioactive Peptide) + UAS-GFP. from Neuron 52(3):425-436. 2006 http://dx.doi.org/10.1016/j.neuron.2006.08.028

Example of UAS/Gal4 in larval brain of D. melanogaster. CCAP-Gal4 (Crustacean Cardioactive Peptide) + UAS-GFP.
from Neuron 52(3):425-436. 2006
doi: 10.1016/j.neuron.2006.08.028

These neurogenic manipulation technologies are constructed on the Gal4 /UAS platform technology that is so well developed in the Drosophila melanogaster system. The existence of many Gal4 ‘driver’ lines that express Gal4 in very specific neurons is the cornerstone of neurogenic manipulation using transgenic technologies.

Although not quite as robust as the Gal4 /UAS system in D. melanogaster, this technology is available in a number of other insect systems including Tribolium castaneum, Bombyx mori and Anopheles stephensi. In these non-drosophilid systems The number of Gal4 driver lines is somewhat limited but, with effort, drivers of specific interest could be obtained.

Simplified signalling pathway leading to apoptosis showing how misexpression of Hid, Grim or Reaper will lead to cell death.

Simplified signalling pathway leading to apoptosis showing how misexpression of Hid, Grim or Reaper will lead to cell death.

‘Effectors’ are transgenes regulated by promoters containing Gal4 Upstream Activating Sequences (UAS).

There are effectors that trigger cell death – UAS-reaper, neuronal silencing – UAS-shibirets, and neuronal activation – UAS-TRMP8, to name just a few.

Table 1 in Pauls et al (2014) is a nice summary of 14 UAS-regulated effector transgenes that are used to manipulate neurogenic behavior in one way or another.

Transgenic effectors used by Pauls et al (2014)

Transgenic effectors used by Pauls et al (2014)

Supplemental table 1 is a useful compilation of 44 publications using different effector gene combinations to manipulate neurons and behaviors in Drosophila larvae.

Overall, Pauls et al (2014) report similar although not identical effects of various effector lines within the context of the behavioral paradigms used in the study and their results could help guide future experimental designs not only in D. melanogaster but in other insect as well.

 

Pauls D, von Essen A, Lyutova R, van Giesen L, Rosner R, Wegener C, Sprecher SG (2014) Potency of Transgenic Effectors for Neurogenetic Manipulation in Drosophila Larvae. Genetics  10.1534/genetics.114.172023

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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