Biology subjects

Adams, K. L.

Publications and source records attributed to Adams, K. L..

4 recordsLinked to original sources

bioRxiv2021

A screen for mutants deficient in coronatine-mediated suppression of root immunity identifies Arabidopsis SDA1 as a novel integrator of immunity and phytohormone signaling

Despite the importance of the root immune system in the interaction with rhizosphere microbes, the majority of genetic screens for immunity regulators have been performed in leaves. A previous screen identified 27 hsm (hormone-mediated suppression of MAMP-triggered immunity) mutants that are impaired in jasmonic acid (JA)-mediated suppression of pattern-triggered immunity (PTI) in roots. Here we characterized 16 of the hsm mutants that retain JA sensitivity and are potential negative regulators of root immunity. We found that the majority of hsm mutants show enhanced resistance to Fusarium, a root fungal pathogen; however, only a subset are more resistant to a foliar pathogen. Surprisingly, 12 of 16 hsm mutants are also impaired in abscisic acid (ABA)-mediated suppression of PTI, suggesting a largely shared pathway between JA- and ABA-mediated immune suppression in roots. Although all hsm mutants are insensitive to JA-mediated suppression of root immunity, hsm4 shows hypersensitivity to JA-mediated root growth inhibition and JA-induced gene expression. Consistently, hsm4 is more resistant to leaf pathogens, suggesting that HSM4 is a negative regulator of both root and leaf immunity. Hsm4 was mapped to a mutation in a conserved ARM-repeat protein homologous to yeast SDA1, which has been reported to regulate 60S ribosome biogenesis. As translational reprogramming is a critical layer of immune regulation, this work suggests that AtSDA1 is a novel negative translational regulator of immunity. Additionally, a comprehensive characterization of all 16 hsm mutants provides a genetic toolkit to identify novel mechanisms that regulate root immunity.

plant biology↗

bioRxiv2021

Cuticular hydrocarbons are associated with mating success and insecticide resistance in malaria vectors

Anopheles coluzzii females, important malaria vectors in Africa, mate only once in their lifetime. Mating occurs in aerial swarms with a high male-to-female ratio, where the traits underlying male mating success are largely unknown. Here, we investigated whether cuticular hydrocarbons (CHCs) influence mating success in natural mating swarms in Burkina Faso. As insecticides are widely used in this area for malaria control, we also determined whether CHCs affect insecticide resistance levels. We find that mated males have higher CHC abundance than unmated controls, suggesting CHCs could be a determinant of mating success. Additionally, mated males have higher insecticide resistance under pyrethroid challenge, and we show a link between resistance intensity and CHC abundance. Taken together, our results reveal overlapping roles played by CHCs in mate choice and insecticide resistance, and point to sexual selection for insecticide resistance traits that limit the efficacy of our best malaria control tools.

ecology↗

bioRxiv2021

Wolbachia cifB induces cytoplasmic incompatibility in the malaria mosquito

Wolbachia infections are a fascinating example of reproductive parasitism with strong potential to combat vector-borne diseases, due to their combined ability to spread in insect populations and block pathogen replication. Though the Wolbachia factors mediating the notable reproductive manipulation cytoplasmic incompatibility (CI) have now been identified as prophage WO genes cifA and cifB, the relative role of these genes is still intensely debated, with different models claiming that CI requires either both factors or cifB alone. Here we investigated whether cifA and cifB are sufficient to induce conditional sterility in the major malaria vector Anopheles gambiae, a species that appears to have limited susceptibility to invasion by Wolbachia. We report that CI can be fully recapitulated in these mosquitoes, and that cifB is sufficient to cause this reproductive manipulation. cifB-induced sterility is fully rescued by high levels of cifA expression in females. Surprisingly, however, when cifA is highly expressed in males alongside cifB, the CI phenotype is attenuated. cifB strongly impairs fertility also when expressed in the female germline, again mitigated by cifA. These data support a system whereby cifB and cifA must be fine-tuned to exercise CI and rescue, respectively, possibly explaining the limited success of Wolbachia at invading Anopheles. Our findings pave the way towards facilitating Wolbachia infections in anopheline vectors, for use in malaria control strategies.

microbiology↗

bioRxiv2021

Antimalarials in mosquitoes overcome Anopheles and Plasmodium resistance to malaria control strategies

The spread of insecticide resistance in Anopheles mosquitoes and drug resistance in Plasmodium parasites is contributing to a global resurgence of malaria, making the generation of control tools that can overcome these issues an urgent public health priority. We recently showed that the transmission of Plasmodium falciparum parasites can be efficiently blocked when exposing Anopheles gambiae females to antimalarials deposited on a treated surface, with no negative consequences on mosquito fitness. Here, we demonstrate this approach can overcome the hurdles of insecticide resistance in mosquitoes and drug resistant in parasites. We show that the transmission-blocking efficacy of mosquito-targeted antimalarials is maintained when field-derived, insecticide resistant Anopheles are exposed to the potent cytochrome b inhibitor atovaquone, demonstrating that this drug escapes insecticide resistance mechanisms that could potentially interfere with its function. Moreover, this approach prevents transmission of field-derived, artemisinin resistant P. falciparum parasites (Kelch13 C580Y mutant), proving that this strategy could be used to prevent the spread of parasite mutations that induce resistance to front-line antimalarials. Atovaquone is also highly effective at limiting parasite development when ingested by mosquitoes in sugar solutions, including in ongoing infections. These data support the use of mosquito-targeted antimalarials as a promising tool to complement and extend the efficacy of current malaria control interventions. Significance StatementEffective control of malaria is hampered by resistance to vector-targeted insecticides and parasite-targeted drugs. This situation is exacerbated by a critical lack of chemical diversity in both interventions and, as such, new interventions are badly needed. Recent laboratory studies have shown that an alternative approach based on treating Anopheles mosquitoes directly with antimalarial compounds can render the vector incapable of transmitting the Plasmodium parasites that cause malaria. While promising, showing that mosquito-targeted antimalarials remain effective against wild parasites and mosquitoes, including drug- and insecticide-resistant populations, respectively, is crucial to the future viability of this approach. In this study, carried out in the US and Burkina Faso, we show that antimalarial exposure is highly effective, even against extremely resistant mosquitoes, and can block transmission of drug-resistant parasites. By combining lab, and field-based studies in this way we have demonstrated that this novel approach can be effective in areas where conventional control measures are no longer as effective.

microbiology↗