168
PH. BULET and S. UTTENWEILER-}OSEPH
7
Induction of the DIMs in Different Mutant Backgrounds
The presence of the DIMs can also be followed in the hemolymph of Drosophila
carrying different mutations. As already discussed in the Introduction, recent
studies based on genetic analysis of the humoral immune response in different
mutant strains of Drosophila has led to the definition of two distinct pathways
regulating the antimicrobial peptide gene expression (Lemaitre et al. 1995,
Lemaitre et al. 1996). In adult Drosophila, the synthesis of the antifungal peptide
drosomycin is predominantly under the control of the Toll pathway, which
includes various genes also involved in the dorso-ventral patterning of Drosophila embryos (for review, see Morisato and Anderson 1995). The expression of
the genes encoding the antibacterial peptides (drosocin, cecropin, attacin, defensin and diptericin) is either controlled by the imd pathway or by both pathways
(for review, see Hoffmann and Reichhart 1997). The regulation of metchnikowin,
which exhibits both antibacterial and antifungal activities, is unique compared to
that of the other antimicrobial peptides, in that it appears to be regulated independently by the Toll and/or the imd pathways (Levashina et al. 1998).
MALDI-TOF MS analysis of the hemolymph of Drosophila carrying a mutation
in genes involved in these immune pathways confirms at the peptide level the
results obtained by Northern blot analysis and demonstrates that expression of
the unidentified DIMs is also controlled by these two pathways. The MALDI -TOF
MS spectra obtained from the hemolymph of unchallenged and immuneimd strain
I ~
1-1
ToW tra in II J m,,,clIl·2S
'J J''''''CII' " I S I
l ______________ U . )~
1()()O
2-1 h po I B e
17 11 >.:ld ll ll k<\"'111
... -161\1 0 3
Y~~JL ~oc
loon
.j ooo
'iIH)()
Fig. 11.S. Induction of the DIMs in different mutants with alteration of the immune response. The
induction of the DIMs was monitored in Drosophila mutants carrying a loss-of-function mutation for
the receptor Toll (ToW) and in Drosophila with an imd mutation background (imd) before (control)
and after a 24h bacterial-challenge (24h post Be). An additional DIM (molecular mass at 4619 Da)
was detected in the Toll" mutant
PH. BULET and S. UTTENWEILER-}OSEPH
7
Induction of the DIMs in Different Mutant Backgrounds
The presence of the DIMs can also be followed in the hemolymph of Drosophila
carrying different mutations. As already discussed in the Introduction, recent
studies based on genetic analysis of the humoral immune response in different
mutant strains of Drosophila has led to the definition of two distinct pathways
regulating the antimicrobial peptide gene expression (Lemaitre et al. 1995,
Lemaitre et al. 1996). In adult Drosophila, the synthesis of the antifungal peptide
drosomycin is predominantly under the control of the Toll pathway, which
includes various genes also involved in the dorso-ventral patterning of Drosophila embryos (for review, see Morisato and Anderson 1995). The expression of
the genes encoding the antibacterial peptides (drosocin, cecropin, attacin, defensin and diptericin) is either controlled by the imd pathway or by both pathways
(for review, see Hoffmann and Reichhart 1997). The regulation of metchnikowin,
which exhibits both antibacterial and antifungal activities, is unique compared to
that of the other antimicrobial peptides, in that it appears to be regulated independently by the Toll and/or the imd pathways (Levashina et al. 1998).
MALDI-TOF MS analysis of the hemolymph of Drosophila carrying a mutation
in genes involved in these immune pathways confirms at the peptide level the
results obtained by Northern blot analysis and demonstrates that expression of
the unidentified DIMs is also controlled by these two pathways. The MALDI -TOF
MS spectra obtained from the hemolymph of unchallenged and immuneimd strain
I ~
1-1
ToW tra in II J m,,,clIl·2S
'J J''''''CII' " I S I
l ______________ U . )~
1()()O
2-1 h po I B e
17 11 >.:ld ll ll k<\"'111
... -161\1 0 3
Y~~JL ~oc
loon
.j ooo
'iIH)()
Fig. 11.S. Induction of the DIMs in different mutants with alteration of the immune response. The
induction of the DIMs was monitored in Drosophila mutants carrying a loss-of-function mutation for
the receptor Toll (ToW) and in Drosophila with an imd mutation background (imd) before (control)
and after a 24h bacterial-challenge (24h post Be). An additional DIM (molecular mass at 4619 Da)
was detected in the Toll" mutant