Biology subjects

Pedra, J. H.

Publications and source records attributed to Pedra, J. H..

3 recordsLinked to original sources

bioRxiv2023

Genetic manipulation of an Ixodes scapularis cell line

Although genetic manipulation is one of the hallmarks in model organisms, its applicability to non-model species has remained difficult due to our limited understanding of their fundamental biology. For instance, manipulation of a cell line originated from the blacklegged tick Ixodes scapularis, an arthropod that serves as a vector of several human pathogens, has yet to be established. Here, we demonstrate the successful genetic modification of the commonly used tick ISE6 line through ectopic expression and clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) genome editing. We performed ectopic expression using nucleofection and attained CRISPR-Cas9 editing via homology dependent recombination. Targeting the E3 ubiquitin ligase X-linked inhibitor of apoptosis (xiap) and its substrate p47 led to alteration in molecular signaling within the immune deficiency (IMD) network and increased infection of the rickettsial agent Anaplasma phagocytophilum in I. scapularis ISE6 cells. Collectively, our findings complement techniques for genetic engineering of ticks in vivo and aid in circumventing the long-life cycle of I. scapularis, of which limits efficient and scalable molecular genetic screens. ImportanceGenetic engineering in arachnids has lagged compared to insects, largely because of substantial differences in their biology. This study unveils the implementation of ectopic expression and CRISPR-Cas9 gene editing in a tick cell line. We introduced fluorescently tagged proteins in ISE6 cells and edited its genome via homology dependent recombination. We ablated the expression of xiap and p47, two signaling molecules present in the immune deficiency (IMD) pathway of I. scapularis. Impairment of the tick IMD pathway, an analogous network of the tumor necrosis factor receptor in mammals, led to enhanced infection of the rickettsial agent A. phagocytophilum. Altogether, our findings provide a critical technical resource to the scientific community to enable a deeper understanding of biological circuits in the blacklegged tick Ixodes scapularis.

genetics↗

bioRxiv2023

Metabolic disruption impacts tick fitness and microbial relationships

Arthropod-borne microbes rely on the metabolic state of a host to cycle between evolutionarily distant species. For instance, arthropod tolerance to infection may be due to redistribution of metabolic resources, often leading to microbial transmission to mammals. Conversely, metabolic alterations aids in pathogen elimination in humans, who do not ordinarily harbor arthropod-borne microbes. To ascertain the effect of metabolism on interspecies relationships, we engineered a system to evaluate glycolysis and oxidative phosphorylation in the tick Ixodes scapularis. Using a metabolic flux assay, we determined that the rickettsial bacterium Anaplasma phagocytophilum and the Lyme disease spirochete Borrelia burgdorferi, which are transstadially transmitted in nature, induced glycolysis in ticks. On the other hand, the endosymbiont Rickettsia buchneri, which is transovarially maintained, had a minimal effect on I. scapularis bioenergetics. Importantly, the metabolite {beta}-aminoisobutyric acid (BAIBA) was elevated during A. phagocytophilum infection of tick cells following an unbiased metabolomics approach. Thus, we manipulated the expression of genes associated with the catabolism and anabolism of BAIBA in I. scapularis and detected impaired feeding on mammals, reduced bacterial acquisition, and decreased tick survival. Collectively, we reveal the importance of metabolism for tick-microbe relationships and unveil a valuable metabolite for I. scapularis fitness.

microbiology↗

bioRxiv2020

Immune factor of bacterial origin protects ticks against host microbial commensals

Hard ticks are blood-feeding arthropods that carry and transmit microbes to their vertebrate hosts1. Tick-borne disease cases have been on the rise over the last several decades, drawing much-needed attention to the molecular interplay between transmitted pathogens and their human hosts. However, far less is known about how ticks control their own microbes, which is critical for understanding how zoonotic transmission cycles persist. We previously found that ticks horizontally acquired an antimicrobial toxin gene from bacteria known as domesticated amidase effector 2 (dae2)2. Here we show that this effector from the tick vector Ixodes scapularis (Dae2Is) has structurally and biochemically diverged from ancestral bacterial representatives, expanding its antibacterial targeting range to include host skin microbes. Disruption of dae2Is increases the burden of skin-associated staphylococci within I. scapularis and adversely affects tick fitness, suggesting resistance of host microbes may be important for the parasitic blood-feeding lifestyle. In contrast, Dae2Is has no intrinsic ability to kill Borrelia burgdorferi, the tick-borne bacterium of Lyme disease. Our observations suggest that ticks have evolved to tolerate their own symbionts while resisting host skin commensals, which we discover are natural opportunistic pathogens of ticks. This work moves our understanding of vector biology beyond a human-centric view: just as tick commensals are pathogenic to humans, so too do our commensals pose a threat to ticks. These observations illuminate how a complex and mirrored set of interkingdom interactions between blood-feeding vectors, their hosts, and associated microbes can ultimately lead to disease.

evolutionary biology↗