Fluorescence-guided Single Sensillum Recording

Fluorescence-guided Single Sensillum Recordings (FgSSR) is a method for performing GFP-targeted SSR in Drosophila.

Full details can be found in Lin and Potter, PLoS One, 2015

 

Traditional single sensillum recordings (SSR) rely on the sizes, shapes, locations and neuronal odor responses (typically to a panel of up to 10 standard odors) to correctly identify target sensilla. We acquired all available OrX-Gal4 lines from the Bloomington Stock Center, and validated which lines, when combined with 10xUAS-IVS-mCD8GFP (on Chromosome 2) or 15xUAS-IVS-mCD8GFP (on Chromosome 3), drove sufficient expression in only a single type of olfactory neuron and were still strong enough to allow identification of sensilla when viewed on a SSR compound microscope setup (see Table below). This significantly shortens the time span needed to identify small sensilla (e.g. ab4-ab10, pb1-3, ai1-3) but also provide a direct method to record from genetically identifiable sensilla.

 

Sensilla (Neuron)

Receptors

Bloomington Stocks for Validated transgenic lines for FgSSRa

Suggested mounting positions

ab1

Or92a, Or42b, Gr21a, Or10a

No needb

Medial

ab2 (A)

Or59b

23897

Medial

ab2 (B)

Or85a

24461

Medial

ab3 (A)

Or22a

9951

Medial

ab3 (B)

Or85b

23911

Medial

ab4 (A)

Or7a

GAL4 Knock-In

Posterior

ab4 (B)

Or56a

23896

Posterior

ab5 (A)

Or82a

23126

Posterior

ab5 (B)

Or47a

9982

Posterior

ab6 (B)

Or49b

9986

Posterior

ab7 (A)

Or98a

23141

Medial

ab7 (B)

Or67c

23905

Medial

ab8 (A)

Or43b

23894

Posterior

ab9 (B)

Or67b

9995

Posterior

ab10 (B?)

Or67a

23904

Medial

at1 (A)

Or67d

GAL4 Knock-In

Posterior or Anterior

at4 (A)

Or47b

9983

Posterior or Anterior

at4 (B)

Or65a

9994

Posterior or Anterior

at4 (C)

Or88a

23138

Posterior or Anterior

ai1 (A)

Or13a

23886

Posterior

ai2 (A)

Or83c

23131

Lateral

ai2 (B)

Or23a

9956

Lateral

ai3 (A)

Or19a

23887

Lateral

ai3 (C)

Or43a

9974

Lateral

pb1c (A)

Or42a

9969

Posterior

pb1c (B)

Or71a

23122

Posterior

pb2c (A)

Or33c

9966

Posterior

pb3c (A)

Or59c

23899

Anterior

pb3c (B)

Or85d

24148

Anterior

a  OrX-Gal4 lines on II were recombined with 10xUAS-IVS-mCD8GFP (Chr II attP40; BS#32186).

  OrX-Gal4 lines on III were recombined with 15xUAS-IVS-mCD8GFP (Chr III attP2; BS#32193).

b ab1 sensilla are the only large basiconic sensilla that contain 4 neurons and thus very easily 

   identified.

c Mounting positions of pb sensilla are less strict since they are more uniformly distributed.

  Homozygous lines (OrX-Gal4, UAS-mCD8GFP/OrX-Gal4, UAS-mCD8GFP) are not recommended in

  maxillary palp ORNs as thinner cuticles cause high fluorescence signals from the

  cell bodies. The thicker cuticle of the antenna greatly reduces visible cell body fluorescence and

  allows for the use of homozygous reporter lines when identifying antenna sensilla. Homozygous

  reporter lines are especially useful when targeting trichoid sensillum.

 

This technique helped clarify the classifcation of intermediate and trichoid sensilla.

There are 2 trichoid sensilla in D. melanogaster (at1, at4), and 3 intermediate sensilla (ai1, ai2, ai3). 



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