Limits...
Lack of an antibacterial response defect in Drosophila Toll-9 mutant.

Narbonne-Reveau K, Charroux B, Royet J - PLoS ONE (2011)

Bottom Line: These results have led to the idea that Toll-9 could be a constitutively active receptor that maintain significant levels of antimicrobial molecules and therefore provide constant basal protection against micro-organisms.To test theses hypotheses, we generated and analyzed phenotypes associated with a complete loss-of-function allele of Toll-9.Our results suggest that Toll-9 is neither required to maintain a basal anti-microbial response nor to mount an efficient immune response to bacterial infection.

View Article: PubMed Central - PubMed

Affiliation: Institut de Biologie du Développement de Marseille-Luminy, CNRS UMR 6216/Aix-Marseille II University, Campus de Luminy, Marseille, France.

ABSTRACT
Toll and Toll-like receptors represent families of receptors involved in mediating innate immunity response in insects and mammals. Although Drosophila proteome contains multiple Toll paralogs, Toll-1 is, so far, the only receptor to which an immune role has been attributed. In contrast, every single mammalian TLR is a key membrane receptor upstream of the vertebrate immune signaling cascades. The prevailing view is that TLR-mediated immunity is ancient. Structural analysis reveals that Drosophila Toll-9 is the most closely related to vertebrate TLRs and utilizes similar signaling components as Toll-1. This suggests that Toll-9 could be an ancestor of TLR-like receptors and could have immune function. Consistently, it has been reported that over-expression of Toll-9 in immune tissues is sufficient to induce the expression of some antimicrobial peptides in flies. These results have led to the idea that Toll-9 could be a constitutively active receptor that maintain significant levels of antimicrobial molecules and therefore provide constant basal protection against micro-organisms. To test theses hypotheses, we generated and analyzed phenotypes associated with a complete loss-of-function allele of Toll-9. Our results suggest that Toll-9 is neither required to maintain a basal anti-microbial response nor to mount an efficient immune response to bacterial infection.

Show MeSH

Related in: MedlinePlus

Toll-9−/− mutant emerging length is delay and lifespan is reduced.(A) Toll-9−/− mutant emergence is delayed of one day compared to wild-type +/+ and heterozygous Toll-9−/+. (B) Toll-9−/− and Toll-9−/Def(Toll-9) mutant lifespan is reduced. Median survival is of 32 and 27 days respectively for mutants and 42 days in controls. This reduction is still observed if flies grown on food supplemented with antibiotics (29 in Toll-9−/− versus 41 days in controls).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3046252&req=5

pone-0017470-g002: Toll-9−/− mutant emerging length is delay and lifespan is reduced.(A) Toll-9−/− mutant emergence is delayed of one day compared to wild-type +/+ and heterozygous Toll-9−/+. (B) Toll-9−/− and Toll-9−/Def(Toll-9) mutant lifespan is reduced. Median survival is of 32 and 27 days respectively for mutants and 42 days in controls. This reduction is still observed if flies grown on food supplemented with antibiotics (29 in Toll-9−/− versus 41 days in controls).

Mentions: In order to study Toll-9 receptor function, we generated a complete loss-of-function allele by targeted homologous recombination [44]. 5′ and 3′ flanking regions of homology were introduced into the pW25 vector (Figure 1A) to generate transgenic flies. The Toll-9 gene disruption knock-out candidate flies were screened and verified using PCR (with specific primers in the two flanking regions of Toll-9 -5F and 3R-, within Toll-9 -1 and 21- and within whs -5R and 3F-, Figure 1A, B) and quantitative PCR (using q5 and q3 primers, Figure 1C, D). Toll-9−/− mutants in which both maternal and zygotic contributions have been removed hatched into morphologically normal and fertile adults, although the Toll-9−/− flies emerged one day later than the w control. Indeed, the t50 (time by which 50% of the progeny has emerged) is of 10.7 days for the control and of 11.6 days for Toll-9−/− (Figure 2A). Moreover, Toll-9−/− and Toll-9−/Def(Toll-9) flies showed a reduced lifespan (Figure 2B) with the mean lifespan of w control flies being at 42 days versus 32 and 27 days for Toll-9−/− and Toll-9−/Def(Toll-9) mutant flies, respectively. A similar lifespan shift was observed when flies are grown in axenic conditions (Figure 2B). Finally, an embryonic lethality was observed, since only one third of the expected Toll-9−/− embryos hatched into larvae. The analysis of the dead embryos revealed that the lethality occurs at the end of embryogenesis. In conclusion, loss of Toll-9−/− function is associated with partial embryonic lethality, delay in adult flies emergence and reduced lifespan.


Lack of an antibacterial response defect in Drosophila Toll-9 mutant.

Narbonne-Reveau K, Charroux B, Royet J - PLoS ONE (2011)

Toll-9−/− mutant emerging length is delay and lifespan is reduced.(A) Toll-9−/− mutant emergence is delayed of one day compared to wild-type +/+ and heterozygous Toll-9−/+. (B) Toll-9−/− and Toll-9−/Def(Toll-9) mutant lifespan is reduced. Median survival is of 32 and 27 days respectively for mutants and 42 days in controls. This reduction is still observed if flies grown on food supplemented with antibiotics (29 in Toll-9−/− versus 41 days in controls).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3046252&req=5

pone-0017470-g002: Toll-9−/− mutant emerging length is delay and lifespan is reduced.(A) Toll-9−/− mutant emergence is delayed of one day compared to wild-type +/+ and heterozygous Toll-9−/+. (B) Toll-9−/− and Toll-9−/Def(Toll-9) mutant lifespan is reduced. Median survival is of 32 and 27 days respectively for mutants and 42 days in controls. This reduction is still observed if flies grown on food supplemented with antibiotics (29 in Toll-9−/− versus 41 days in controls).
Mentions: In order to study Toll-9 receptor function, we generated a complete loss-of-function allele by targeted homologous recombination [44]. 5′ and 3′ flanking regions of homology were introduced into the pW25 vector (Figure 1A) to generate transgenic flies. The Toll-9 gene disruption knock-out candidate flies were screened and verified using PCR (with specific primers in the two flanking regions of Toll-9 -5F and 3R-, within Toll-9 -1 and 21- and within whs -5R and 3F-, Figure 1A, B) and quantitative PCR (using q5 and q3 primers, Figure 1C, D). Toll-9−/− mutants in which both maternal and zygotic contributions have been removed hatched into morphologically normal and fertile adults, although the Toll-9−/− flies emerged one day later than the w control. Indeed, the t50 (time by which 50% of the progeny has emerged) is of 10.7 days for the control and of 11.6 days for Toll-9−/− (Figure 2A). Moreover, Toll-9−/− and Toll-9−/Def(Toll-9) flies showed a reduced lifespan (Figure 2B) with the mean lifespan of w control flies being at 42 days versus 32 and 27 days for Toll-9−/− and Toll-9−/Def(Toll-9) mutant flies, respectively. A similar lifespan shift was observed when flies are grown in axenic conditions (Figure 2B). Finally, an embryonic lethality was observed, since only one third of the expected Toll-9−/− embryos hatched into larvae. The analysis of the dead embryos revealed that the lethality occurs at the end of embryogenesis. In conclusion, loss of Toll-9−/− function is associated with partial embryonic lethality, delay in adult flies emergence and reduced lifespan.

Bottom Line: These results have led to the idea that Toll-9 could be a constitutively active receptor that maintain significant levels of antimicrobial molecules and therefore provide constant basal protection against micro-organisms.To test theses hypotheses, we generated and analyzed phenotypes associated with a complete loss-of-function allele of Toll-9.Our results suggest that Toll-9 is neither required to maintain a basal anti-microbial response nor to mount an efficient immune response to bacterial infection.

View Article: PubMed Central - PubMed

Affiliation: Institut de Biologie du Développement de Marseille-Luminy, CNRS UMR 6216/Aix-Marseille II University, Campus de Luminy, Marseille, France.

ABSTRACT
Toll and Toll-like receptors represent families of receptors involved in mediating innate immunity response in insects and mammals. Although Drosophila proteome contains multiple Toll paralogs, Toll-1 is, so far, the only receptor to which an immune role has been attributed. In contrast, every single mammalian TLR is a key membrane receptor upstream of the vertebrate immune signaling cascades. The prevailing view is that TLR-mediated immunity is ancient. Structural analysis reveals that Drosophila Toll-9 is the most closely related to vertebrate TLRs and utilizes similar signaling components as Toll-1. This suggests that Toll-9 could be an ancestor of TLR-like receptors and could have immune function. Consistently, it has been reported that over-expression of Toll-9 in immune tissues is sufficient to induce the expression of some antimicrobial peptides in flies. These results have led to the idea that Toll-9 could be a constitutively active receptor that maintain significant levels of antimicrobial molecules and therefore provide constant basal protection against micro-organisms. To test theses hypotheses, we generated and analyzed phenotypes associated with a complete loss-of-function allele of Toll-9. Our results suggest that Toll-9 is neither required to maintain a basal anti-microbial response nor to mount an efficient immune response to bacterial infection.

Show MeSH
Related in: MedlinePlus