Biology subjects

Klug, D.

Publications and source records attributed to Klug, D..

8 recordsLinked to original sources

bioRxiv2026

Differential signaling by two Plasmodium sporozoite adhesins mediates transmission of malaria parasites

Malaria parasites are transmitted in the form of Plasmodium sporozoites, highly motile cells that form in oocysts at the mosquito midgut and invade salivary glands. After transmission to the vertebrate host, sporozoites migrate in the skin and liver to enter and differentiate in hepatocytes. Sporozoite migration and invasion are mediated by surface adhesins which link the extracellular substrate to the actin-myosin motor, providing the force for gliding motility. Here we show that two adhesins, TRAP and TRP1, use different extracellular domains and distinct cytoplasmic signaling to mediate salivary gland invasion and gliding motility. The extracellular thrombospondin repeat (TSR) of TRP1 but not the TSR of TRAP is essential for gliding and transmission and the TSR of TRAP can only partially rescue TSR function in TRP1. Furthermore, the cytoplasmic domain of TRAP cannot replace the equivalent domain of TRP1, which is essential for gliding and salivary gland invasion. This suggests that sporozoites integrate signals through multiple essential outside-in signaling pathways to achieve migration and invasion.

cell biology↗

bioRxiv2026

Genetic ablation of visual perception reveals behaviour changes in male and female malaria mosquitoes

The role of vision in the behavior of blood-feeding mosquitoes has remained largely overlooked, particularly in species of the Anopheles genus, despite their significant impact on global health. While the importance of olfactory and thermal cues in host-seeking is well established, the contribution of visual stimuli to mating and feeding behavior remains far less understood. In particular, Anopheles mosquitoes exhibit complex swarming behavior that depends on visual input, suggesting an underexplored avenue of research with direct implications for vector control. This study introduces a genetically modified mosquito line lacking the enzyme Tan, a hydrolase involved in both dopamine and histamine metabolism, to investigate the behavioral relevance of visual cues in Anopheles. Through a combination of behavioral assays and controlled laboratory experiments, the impact of visual disruption on attraction to UV-B light, host-seeking, and blood-feeding success was assessed. The findings demonstrate a reduced light-dependent attraction in both Anopheles males and females, suggesting an impairment in visual processing or a related behavioral response. This observation has implications for reproductive success and potential adaptation to anthropogenic environments with artificial light. By leveraging this novel knockout model, the study offers new tools and perspectives to better understand how vision shapes mosquito behavior and how this knowledge could be harnessed in the development of next-generation vector control strategies.

animal behavior and cognition↗

bioRxiv2025

Yellow shapes mosquito pigmentation and vector competence to Plasmodium berghei

The insect-specific yellow gene, first described over a century ago, remains enigmatic despite its conserved role in pigmentation. In the malaria vector mosquito Anopheles coluzzii, yellow is strongly expressed during juvenile stages and in adult ovaries, mirroring pigmentation patterns that likely enhance desiccation resistance, camouflage, and reproductive fitness. To dissect its function, we generated a complete knockout allele yellow(-)KI by replacing the first exon with an EGFP reporter, and introgressed it into multiple genetic backgrounds. Loss of yellow abolished black cuticle pigmentation and delayed larval development but left adult lifespan unaffected. Developmental delay likely impaired mating success in competition with wild-type mosquitoes, hastening the decline of the X-linked yellow(-)KI allele. Notably, yellow(-)KI females showed a consistent twofold increase in susceptibility to the rodent malaria parasite Plasmodium berghei, independent of the complement factor TEP1 and melanization, whereas infection with P. falciparum was unchanged. Antibiotic treatment reversed the heightened P. berghei susceptibility, implicating altered gut microbiota as a mediator. Our findings reveal that yellow not only shapes pigmentation but also indirectly modulates vector competence through microbiota-dependent mechanisms, underscoring the complex interplay between cuticle biochemistry, microbial ecology, and pathogen transmission.

microbiology↗

bioRxiv2022

Conformational change of the Plasmodium TRAP I domain is essential for sporozoite migration and transmission of malaria

Eukaryotic cell adhesion and migration relies on surface adhesins connecting extracellular ligands to the intracellular actin cytoskeleton. Plasmodium sporozoites are transmitted by mosquitoes and rely on adhesion and gliding motility to colonize the salivary glands and to reach the liver after transmission. During gliding the essential sporozoite adhesin TRAP engages actin filaments in the cytoplasm of the parasite., while binding ligands on the substrate through its inserted (I)-domain. Crystal structures of TRAP from different Plasmodium species revealed the I-domain in closed and open conformations. Here, we probe the importance of these two conformational states by generating parasites expressing versions of TRAP with the I-domain stabilized in either the open or closed state with disulfide bonds. Strikingly, both mutations impact sporozoite gliding, mosquito salivary gland entry and transmission. Absence of gliding in sporozoites expressing the open TRAP I-domain could be partly rescued by adding a reducing agent. This suggests that dynamic conformational change is required for ligand binding, gliding motility and organ invasion and hence sporozoite transmission from mosquito to mammal.

cell biology↗

bioRxiv2022

A population modification gene drive targeting both Saglin and Lipophorin disables Plasmodium transmission in Anopheles mosquitoes

Lipophorin is an essential, highly expressed lipid transport protein that is secreted and circulates in insect hemolymph. We hijacked the Anopheles coluzzii Lipophorin gene to make it co-express a single-chain version of antibody 2A10, which binds sporozoites of the malaria parasite Plasmodium falciparum. The resulting transgenic mosquitoes show a markedly decreased ability to transmit Plasmodium berghei expressing the P. falciparum circumsporozoite protein. To force the spread of this anti-malarial transgene in a mosquito population, we designed and tested several CRISPR/Cas9-based gene drives. One of these is installed in, and disrupts, the pro-parasitic gene Saglin and also cleaves wild-type Lipophorin, causing the anti-malarial modified Lipophorin version to replace the wild type and hitch-hike together with the Saglin drive. Although generating drive-resistant alleles and showing instability in its gRNA-encoding multiplex array, the Saglin-based gene drive reached high levels in caged mosquito populations and efficiently promoted the simultaneous spread of the antimalarial Lipophorin::Sc2A10 allele. This combination is expected to decrease parasite transmission via two different mechanisms. This work contributes to the design of novel strategies to spread antimalarial transgenes in mosquitoes, and illustrates some expected and unexpected outcomes encountered when establishing a population modification gene drive.

genetics↗

bioRxiv2022

The salivary protein Saglin facilitates efficient midgut colonization of Anopheles mosquitoes by malaria parasites

Malaria is caused by the unicelullar parasite Plasmodium which is transmitted to humans through the bite of infected female Anopheles mosquitoes. To initiate sexual reproduction and to infect the midgut of the mosquito, Plasmodium gametocytes are able to recognize the intestinal environment after being ingested during blood feeding. A shift in temperature, pH change and the presence of the insect-specific compound xanthurenic acid have been shown to be important stimuli perceived by gametocytes to become activated and proceed to sexual reproduction. Here we report that the salivary protein Saglin, previously proposed to be a receptor for the recognition of salivary glands by sporozoites, facilitates Plasmodium colonization of the mosquito midgut, but does not contribute to salivary gland invasion. In mosquito mutants lacking Saglin, Plasmodium infection of Anopheles females is greatly reduced, resulting in impaired transmission of sporozoites at low infection densities. Interestingly, our results suggest that Saglin, present in mosquito saliva, must be ingested with the blood meal to affect Plasmodium development, indicating a previously unknown host-pathogen interaction. Furthermore, we were able to show that saglin deletion has no fitness cost in laboratory conditions, suggesting this gene would be an interesting target for gene drive approaches.

microbiology↗

bioRxiv2021

A pigment-deficient mosquito line with fluorescent salivary glands enables in vivo imaging of individual Plasmodium sporozoites

Mosquito saliva is a vehicle for the transmission of vector borne pathogens such as Plasmodium parasites and different arboviruses. Despite the key role of the salivary glands in the process of disease transmission, knowledge of host-pathogen interactions taking place within this organ is very limited. To improve the experimental tractability of the salivary glands, we have generated fluorescent reporter lines in the African malaria mosquito Anopheles coluzzii using the salivary gland-specific promoters of the anopheline antiplatelet protein (AAPP), the triple functional domain protein (TRIO) and saglin (SAG). Promoter activity was specifically observed in the distal-lateral lobes or in the median lobe of the salivary gland. Besides a comparison of the expression patterns of the selected promoters, the fluorescent probes allowed us to evaluate the inducibility of the selected promoters upon blood feeding and to measure intracellular redox changes. We also combined the aapp-DsRed fluorescent reporter line with a pigmentation-deficient yellow(-) mosquito mutant to assess the feasibility of in vivo microscopy of parasitized salivary glands. This combination allowed locating the salivary gland through the cuticle and imaging of individual sporozoites in vivo, which facilitates live imaging studies of salivary gland colonization by Plasmodium sporozoites.

microbiology↗

bioRxiv2018

Cationic charge and polyspecificity of an integrin domain regulates infectivity of malaria parasites

Cell-cell and cell-substrate adhesion is critical for many functions in life. In eukaryotes, I-domains mediate functions as divergent as tissue traversal by malaria-causing Plasmodium parasites as well as cell adhesion and migration by human leucocytes. The I-domain containing protein TRAP is important for Plasmodium sporozoite motility and invasion. Here we show that the I-domain of TRAP is required to mediate adhesional properties which can be partially preserved when the native I-domain is replaced by I-domains from human integrins or from an apicomplexan parasite that does not infect insects. By putting in vivo data and structural features in perspective we conclude that polyspecificity and positive charge around the ligand binding site of the I-domain are important for TRAP function. Our data suggest a highly preserved functionality of I-domains across eukaryotic evolution that is used by apicomplexan parasites to invade a broad range of tissues in a variety of hosts.

microbiology↗