Figures
Fig. 1: tßhnM18
mutant flies show a reduced sugar response compared to wild type
flies after 20 h of starvation.
Proboscis extension
response was measured in wild type (n = 79, white) and
mutant flies (n = 65, grey). A. Fraction of flies that
responded to several concentrations of sucrose. Data points indicate
the mean. B. For each fly, we calculated a response score
corresponding to the total number of all positive responses over the
seven sugar presentations. This score is depicted in boxplots
representing the median (bar), the 75%- and 25%-quartiles (box) and
data within 1.5 times the interquartile range (whiskers). Data
outside 1.5 times the interquartile range are considered as outliers
(black dots). Numbers inside the boxes indicate sample sizes. The
asterisk denotes significant difference between genotypes (Wilcoxon
rank sum test, p < 0.05).
Fig. 2: Change in
hemolymph glucose and trehalose after starvation is smaller in
tßhnM18 mutants than in wild type.
The trehalose and
glucose content was measured in the hemolymph of fed and 20 h starved
mutant (grey) and wild type (white) flies. A. The concentration of
trehalose and glucose in hemolymph is calculated from the glucose
absorbance at 540nm and shown as mean ± SEM. Numbers in bars
indicate sample size. B. The glucose absorbance in starved animals
was normalized to the absorbance in fed animals for each genotype.
The change in absorbance after starvation is shown as mean ± SEM
(Welch Two Sample t-Test, n = 12, p < 0.05).
Fig. 3: tßhnM18
mutants survive longer under starvation conditions.
Survival under
starvation conditions was determined by counting dead flies in vials
containing either mutants (n = 16, grey) or wild type flies
(n = 16, white) every 3 h at daytimes. A. Proportion
of living animals per vial is depicted over time in mean ± SEM
(n = 16). B. The time point of 50% death rate (LD50)
is depicted as boxplots. The asterisk indicates significant
difference between genotypes (Wilcoxon rank sum test, p < 0.05).
Numbers beneath boxes indicate sample size.
Fig. 4: tßh
induction immediately before testing increases sucrose response in
mutants.
Total number of
proboscis extension responses of wild type flies (white), mutants
(grey), and mutants with hsp-tßh construct (blue) represented as
boxplots. A. Temperature-induced ubiquitous expression of the tßh
gene increases the sucrose responsiveness when expression is induced
3 h before testing. B. Inducing tßh-expression once a day
during starvation but not before the test does not rescue the
mutants’ sucrose response phenotype. Small numbers within graph
indicate sample sizes, small letters denote significant difference
between groups (paired Wilcoxon rank sum test, p < 0.05).
Fig. 5: Effect of
starvation on taste neuron sensitivity.
Electrophysiological
recording from different gustatory sensilla on the labellum A. in
sated and starved tßhnM18 mutants (grey) and controls (white) and B.
in sated (white) and starved (grey) wild type flies. Extracellular
action potentials within 1 s after stimulation onset were
counted and plotted as boxplots. Numbers represent the sample size of
the recorded sensilla; asterisks indicate statistical differences
between groups (Wilcoxon rank sum test, p < 0.05).
Fig. 6: TA- and
OA-receptor mutants are differently affected in survival and sucrose
response.
Female TA or
OA-receptor mutants (grey) and their respective genetic background
control (white) are tested in sucrose response (A) or survival (B).
A. The total number of proboscis extensions to sucrose in Octß2 and
two different OAMB receptor mutants are not affected. The TA-receptor
mutants TyrRf05682, TyrRII∆24, and honoka respond less to sucrose,
the double mutant TyrRII-TyrR∆124 is not affected. B. The LD50 in
Octβ2R∆3.22 and Octß2R∆4.3 is later. Neither of the oamb
mutants shows a change in survival. TyrRf05682, honoka, and the
double mutant TyrRII-TyrR∆124 survive longer. TyrRII∆29 is not
affected.
Small numbers within
graph indicate sample sizes, small letters or asterisks indicate
significant difference between regarding receptor mutant and the
control (Wilcoxon rank sum test, p < 0.05).
Fig. 7: Spatial
rescues of the tßhnM18 mutant.
Total number of
proboscis extensions of GAL4-controls (grey) and the same GAL4-lines
expressing UAS-tßh (blue), both in tßh mutant background,
illustrated as boxplots. tßh expression in mutant background could
increase the sugar response when expressed using Actin-GAL4,
Tdc1-GAL4, and nSyb-GAL4 but not when expressed using Tdc2-GAL4 or
NP7088-GAL4. Small numbers in boxes indicate sample sizes. Asterisks
denote significant difference between mutant and rescue group
(Wilcoxon rank sum test, p < 0.05).
Table 1: TA- and
OA-receptor mutants are differently affected in survival and sugar
response.
Horizontal arrows
indicate no effect. Arrows indicate significant difference to
respective control and illustrate the trend of the data.