Biology subjects

Yarza, F.

Publications and source records attributed to Yarza, F..

3 recordsLinked to original sources

bioRxiv2021

Lizard feeding enhances Ixodes pacificus vector competency

A vectors susceptibility and ability to transmit a pathogen-- termed vector competency--determines disease outcomes, yet the ecological factors influencing tick vector competency remain largely unknown. Ixodes pacificus, the vector of Borrelia burgdorferi (Bb) in the western U.S., feeds on rodents, birds, and lizards. While rodents and birds are reservoirs for Bb and infect juvenile ticks, lizards are Bb-refractory. Despite I. pacificus feeding on a range of hosts, it is undetermined how larval host bloodmeal identity affects future nymphal vector competency. We experimentally evaluate the influence of larval host bloodmeal on Bb acquisition by nymphal I. pacificus. Larval I. pacificus were fed on either lizards or mice and after molting, nymphs were fed on Bb-infected mice. We found that lizard-fed larvae were significantly more likely to become infected with Bb during their next bloodmeal than mouse-fed larvae. We also conducted the first RNA-seq analysis on whole-bodied I. pacificus and found significant upregulation of antioxidants and antimicrobial peptides in the lizard-fed group. Our results indicate that the lizard bloodmeal significantly alters vector competency and gene regulation in ticks, highlighting the importance of host bloodmeal identity in disease transmission and upends prior notions about the role of lizards in Lyme disease transmission.

ecology↗

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↗

bioRxiv2019

Lanthanide transport, storage, and beyond: genes and processes contributing to XoxF function in Methylorubrum extorquens AM1

Lanthanide elements have been recently recognized as "new life metals" for diverse environmental microorganisms including Gram-negative methylotrophic bacteria and strains of Pseudomonas and Bradyrhizobium. Yet much remains unknown regarding lanthanide acquisition and homeostasis. In Methylorubrum extorquens AM1, the periplasmic lanthanide-dependent methanol dehydrogenase XoxF1 produces formaldehyde, which is lethal if allowed to accumulate. This property enabled a transposon mutagenesis study to expand knowledge of the metabolic network required for methanol oxidation when lanthanides are available. Growth studies were conducted to detail the involvement of novel gene products that impact the ability of XoxF-type enzymes to oxidize methanol to formaldehyde. The identified genes encode an MxaD homolog, an ABC-type transporter, an aminopeptidase, a putative homospermidine synthase, and two genes of unknown function annotated as orf6 and orf7. Lanthanide transport and trafficking genes were also identified. Growth and lanthanide uptake were measured using strains lacking individual lanthanide transport cluster genes and transmission electron microscopy was used to visualize lanthanide localization. We corroborated previous reports that a TonB-ABC transport system is required for lanthanide incorporation to the cytoplasm. However, cells are able to acclimate overtime and bypass the requirement for the TonB outer membrane transporter to allow expression of xoxF1 and growth. Transcriptional reporter fusions show that excess lanthanides repress the gene encoding the TonB-receptor. Using growth studies along with energy dispersive X-ray spectroscopy and transmission electron microscopy, we demonstrate that lanthanides are stored as cytoplasmic inclusions that resemble polyphosphate granules. IMPORTANCEThe increasing genetic and biochemical evidence that lanthanide-dependent enzymes are widespread among numerous environmental microbes leads to the parallel questions of how these insoluble metals are scavenged, transported, and used by bacteria. Results herein describe the contribution of the different gene products that constitute the lanthanide utilization and transport machinery in the methylotroph M. extorquens AM1 and highlight possible redundancies by periplasmic components. The discovery and characterization of intracellular lanthanide storage in mineral form by these microbes opens the possibility of using methylotrophic platforms for concentration and recovery of these critical energy metals from diverse sources. In addition, methylotrophs are effective biotechnological platforms for the production of biofuels and bioplastics from pollutants such as methane, and inexpensive carbon feedstocks like methanol. Defining the lanthanide acquisition, transport, and storage machinery is a step forward in designing a sustainable platform to recover lanthanides efficiently.

microbiology↗