Biology subjects

Kilpatrick, A. M.

Publications and source records attributed to Kilpatrick, A. M..

12 recordsLinked to original sources

bioRxiv2026

RAPID DECLINE OF NESTING PEREGRINE FALCONS IN THE SAN FRANCISCO BAY REGION OF CALIFORNIA SYNCHRONOUS WITH AN H5N1 OUTBREAK

After rebounding from near extirpation during the organochlorine era, breeding Peregrine Falcons (Falco peregrinus) in California are again facing adversity, this time consistent with an outbreak of a highly pathogenic avian influenza. Following the first detection of the H5N1 variant clade 2.3.4.4b virus in California wild birds in July 2022, we assembled data from long-term monitoring (2000-2025) of peregrine breeding territory occupancy in the broad vicinity of San Francisco Bay to examine possible impacts on falcon populations. Prior to the outbreak, 47 focal breeding territories had shown nearly complete occupancy by pairs (98.5% of 390 site-years), with very few vacancies, single birds in attendance, or subadult pair members. Within 8 mo of the outbreak, occupancy had dropped to 65.1%, and 2 yrs later (2025), only 36.2% of sites remained occupied. An uptick in site-occupancy by single birds also occurred after the outbreak, but it is unclear whether these were survivors or floaters attempting to fill vacant territories where both pair members had perished. The high vacancy rates signaled an impact upon floaters (nonbreeding adults) that normally buffer breeding site-occupancy in healthy peregrine populations. From October 2022 through November 2025, 17 peregrine fatalities were diagnosed with H5N1 within the counties comprising our study area. Evidence that H5N1 caused these territory vacancies includes, (1) the striking temporal coincidence of occupancy loss with the outbreak, and (2) the lethality of the virus to peregrines and its confirmed presence in peregrine prey in our study area. Our study reaffirms the value of long-term territory occupancy monitoring in this sentinel species.

ecology↗

bioRxiv2024

Transinfection of Wolbachia wAlbB into Culex quinquefasciatus mosquitoes does not alter vector competence for Hawaiian avian malaria (Plasmodium relictum GRW4)

Avian malaria is expanding upslope with warmer temperatures and driving multiple species of Hawaiian birds towards extinction. Methods to reduce malaria transmission are urgently needed to prevent further declines. Releasing Wolbachia-infected incompatible male mosquitoes suppress mosquito populations and releasing Wolbachia-infected female mosquitoes could reduce pathogen transmission if the Wolbachia strain reduced vector competence. We cleared Culex quinquefasciatus of their natural Wolbachia pipientis wPip infection and transinfected them with Wolbachia wAlbB isolated from Aedes albopictus. We show that wAlbB infection was transmitted transovarially, and demonstrate cytoplasmic incompatibility with wild-type mosquitoes infected with wPip from Oahu and Maui, Hawaii. We measured vector competence for avian malaria, Plasmodium relictum, lineage GRW4, of seven mosquito lines (two with wAlbB; three with natural wPip infection, and two cleared of Wolbachia infection) by allowing them to feed on canaries infected with recently collected field isolates of Hawaiian P. relictum. We tested 73 groups (Ntotal = 1176) of mosquitoes for P. relictum infection in abdomens and disseminated (thorax) infections 6-14 days after feeding across a range of parasitemias from 0.028% to 2.49%, and a smaller subset of salivary glands. We found no measurable effect of Wolbachia on any endpoint, but strong effects of parasitemia, days post feeding, and mosquito strain on both abdomen infection prevalence and disseminated infection prevalence. These results suggest that releasing male wAlbB-infected C. quinquefasciatus mosquitoes could suppress wPip-infected mosquito populations, but would have little positive or negative impact on mosquito vector competence for P. relictum if wAlbB became established in local mosquito populations. More broadly, the lack of Wolbachia effects on vector competence we observed highlights the variable impacts of both native and transfected Wolbachia infections in mosquitoes.

ecology↗

bioRxiv2023

Electroconvulsive stimuli reverse neuro-inflammation and behavioral deficits in a mouse model of depression.

BackgroundElectroconvulsive therapy is a fast, safe, and effective treatment for severe clinical depression but there is an ongoing search for mechanistic insights. MethodsWe used a mouse neuro-endocrine model of depression to examine behavioral, cellular, and molecular effects of electroconvulsive stimuli (ECS). ResultsThe behavioral response to repeated ECS correlated with adult neurogenesis, more strongly in the ventral than dorsal hippocampus. Subsequent RNA-seq analysis targeting the ventral subgranular zone (SGZ) delineated ECS-responsive molecular pathways that were shared between naive and depressive-state conditions, and which may represent core biological responses to seizure induction. Other pathways responded to ECS preferentially in the depressive state, suggesting further state- specific mechanisms. By comparing gene set pathways reciprocally altered in depressed-state animals then reversed by ECS, we identified and validated neuro-inflammation as a candidate regulator of the antidepressant response. We further identified 56 novel candidate antidepressant response genes in the ventral SGZ that may contribute to recovery, half of which have been implicated in human neuropsychiatric phenotypes. ConclusionsElectroconvulsive stimuli reverse neuro-inflammation in a mouse model of depression. The results offer a detailed molecular characterization of potential SGZ antidepressant response-specific genes and pathways in brain regions implicated in depression.

neuroscience↗

bioRxiv2022

Host abundance and heterogeneity in infectiousness determine extent of the environmental reservoir

Environmental pathogen reservoirs exist for many globally important diseases and can fuel epidemics, influence pathogen evolution, and increase the threat of host extinction. Species composition can be an important factor that shapes reservoir dynamics and ultimately determines the outcome of a disease outbreak. However, disease induced mortality can change species communities, indicating that species responsible for environmental reservoir maintenance may change over time. Here we examine reservoir dynamics of Pseudogymnoascus destructans, the fungal pathogen that causes white-nose syndrome in bats. We quantified changes in pathogen shedding, infection prevalence and intensity, host abundance, and the subsequent propagule pressure imposed by each species over time. We find that highly shedding species are important during pathogen invasion, but contribute less over time to environmental contamination as they also suffer the greatest declines. Less infected species remain more abundant, resulting in equivalent or higher propagule pressure. More broadly, we demonstrate that high infection intensity and subsequent mortality during disease progression can reduce the contributions of high shedding species to long-term pathogen maintenance.

ecology↗

bioRxiv2022

SEX-BIASED INFECTIONS SCALE TO POPULATION IMPACTS FOR AN EMERGING WILDLIFE DISEASE

Demographic factors are fundamental in shaping infectious disease dynamics. Aspects of populations that create structure, like age and sex, can affect patterns of transmission, infection intensity and population outcomes. However, studies rarely link these processes from individual to population-scale effects. Moreover, the mechanisms underlying demographic differences in disease are frequently unclear. Here, we explore sex-biased infections for a multi-host fungal disease of bats, white-nose syndrome, and link disease-associated mortality between sexes, the distortion of sex ratios, and the potential mechanisms underlying sex differences in infection. We collected data on host traits, infection intensity, and survival of five bat species at 42 sites across seven years. We found females were more infected than males for all five species. Females also had lower apparent survival over winter and accounted for a smaller proportion of populations over time. Notably, female-biased infections were evident by early hibernation and likely driven by sex-based differences in autumn mating behavior. Male bats were more active during autumn which likely reduced replication of the cool-growing fungus. Higher disease impacts in female bats may have cascading effects on bat populations beyond the hibernation season by limiting recruitment and increasing the risk of Allee effects.

ecology↗

bioRxiv2022

Reducing environmentally mediated transmission to moderate impacts of an emerging wildlife disease

O_LIEmerging infectious diseases are a serious threat to wildlife communities, and the ability of pathogens to survive in the environment can exacerbate disease impacts on hosts and increase the likelihood of species extinction. Targeted removal or control of these environmental reservoirs could provide an effective mitigation strategy for reducing disease impacts but is rarely used in wildlife disease control. C_LIO_LIWe examined the effectiveness of managing environmental transmission to reduce impacts of an emerging infectious disease of bats, white-nose syndrome. We used a chemical disinfectant, chlorine dioxide (ClO2), to experimentally reduce Pseudogymnoascus destructans, the fungal pathogen causing WNS, in the environment. We conducted laboratory experiments followed by three years of field trials at four abandoned mines to determine whether ClO2 could effectively reduce P. destructans in the environment, reduce host infection, and limit population impacts. C_LIO_LIClO2 was effective at killing P. destructans in vitro across a range of concentrations. In field settings, higher concentrations of ClO2 treatment sufficiently reduced viable P. destructans conidia in the environment. C_LIO_LIThe reduction in the environmental reservoir at treatment sites resulted in lower fungal loads on bats compared to untreated control populations. Survival following treatment was higher in little brown bats (Myotis lucifugus), and trended higher for tricolored bats (Perimyotis subflavus) compared to untreated sites. C_LIO_LIThese findings support the management of environmental reservoirs as an effective control strategy for wildlife disease and provide a valuable tool for ongoing conservation efforts. More broadly, these results highlight how the intensity of environmental reservoirs can have cascading impacts on host infection and population declines. C_LI

ecology↗

bioRxiv2022

Marked regional glial heterogeneity in the human white matter of the central nervous system

The myelinated white matter tracts of the central nervous system (CNS) are essential for fast transmission of electrical impulses and are commonly affected in neurodegenerative diseases. However, these often uniquely human diseases differentially affect white matter regions, at various ages and between males and females, and we hypothesised that this is secondary to physiological variation in white matter glia with region, age and sex. Using single nucleus RNA sequencing of healthy human post-mortem samples, we find marked glial heterogeneity with tissue region (primary motor cortex, cerebellum, cervical spinal cord), with tissue-specific cell populations of oligodendrocyte precursor cells and astrocytes, and a spinal cord-enriched oligodendrocyte type that appears human-specific. Spinal cord microglia but not astrocytes show a more activated phenotype compared to brain. These regional effects, with additional differentially expressed genes with age and sex in all glial lineages, help explain pathological patterns of disease - essential knowledge for therapeutic strategies.

neuroscience↗

bioRxiv2022

Transcriptional response of individual Hawaiian Culex quinquefasciatus mosquitoes to the avian malaria parasite Plasmodium relictum

Culex quinquefasciatus, the mosquito vector of avian malaria in Hawai{square}i, became established in the islands in the 1820s and the deadly effects of malaria on endemic bird species have been documented for many decades. To evaluate the gene expression response of the mosquito to the parasite, we let the offspring of wild-collected Hawaiian Cx. quinquefasciatus feed on a domestic canary infected with Plasmodium relictum GRW4 freshly isolated from a wild-caught Hawaiian honeycreeper. Control mosquitoes were fed on an uninfected canary. We sequenced the individual transcriptomes of five infected and three uninfected individual mosquitoes at three different stages of the parasite life cycle: 24 h post feeding (hpf) during ookinete invasion; 5 days post feeding (dpf) when oocysts are developing; 10 dpf when sporozoites are released and invade the salivary glands. Differential gene expression analyses showed that during ookinete invasion (24 hpf), genes related to oxidoreductase activity and galactose catabolism had lower expression levels in infected mosquitoes compared to controls. Oocyst development (5 dpf) was associated with reduced expression of a gene with a predicted innate immune function. At 10 dpf, infected mosquitoes had reduced expression levels of a serine protease inhibitor. Overall, the gene expression response of Hawaiian Culex exposed to a Plasmodium infection intensity that occur naturally in Hawaii was low, but more pronounced during ookinete invasion. The low fitness costs often documented in Culex infected with avian Plasmodium likely reflect the relatively small transcriptional changes observed in mosquito genes related to immune response and nutrient metabolism.

microbiology↗

bioRxiv2021

A new SARS-CoV-2 lineage that shares mutations with known Variants of Concern is rejected by automated sequence repository quality control

We report a SARS-CoV-2 lineage that shares N501Y, P681H, and other mutations with known variants of concern, such as B.1.1.7. This lineage, which we refer to as B.1.x (COG-UK sometimes references similar samples as B.1.324.1), is present in at least 20 states across the USA and in at least six countries. However, a large deletion causes the sequence to be automatically rejected from repositories, suggesting that the frequency of this new lineage is underestimated using public data. Recent dynamics based on 339 samples obtained in Santa Cruz County, CA, USA suggest that B.1.x may be increasing in frequency at a rate similar to that of B.1.1.7 in Southern California. At present the functional differences between this variant B.1.x and other circulating SARS-CoV-2 variants are unknown, and further studies on secondary attack rates, viral loads, immune evasion and/or disease severity are needed to determine if it poses a public health concern. Nonetheless, given what is known from well-studied circulating variants of concern, it seems unlikely that the lineage could pose larger concerns for human health than many already globally distributed lineages. Our work highlights a need for rapid turnaround time from sequence generation to submission and improved sequence quality control that removes submission bias. We identify promising paths toward this goal.

genomics↗

bioRxiv2020

Failures of nerve regeneration caused by aging or chronic denervation are rescued by restoring Schwann cell c-Jun

After nerve injury, myelin and Remak Schwann cells reprogram to repair cells specialized for regeneration. Normally providing strong regenerative support, these cells fail in aging animals, and during the chronic denervation that results from the slow growth of axons. This impairs axonal regeneration and causes a significant clinical problem. In mice, we find that repair cells express reduced c-Jun protein as the regenerative support provided by these cells declines in aging animals and during chronic denervation. In both cases, genetically restoring Schwann cell c-Jun levels restores regeneration to that in controls. We identify potential gene candidates mediating this effect and implicate Shh in the control of Schwann cell c-Jun levels. This establishes that a common mechanism, reduced c-Jun in Schwann cells, regulates the success and failure of nerve repair both during aging and chronic denervation. This provides a molecular framework for addressing important clinical problems, and suggests molecular pathways that can be targeted to promote repair in the PNS.

neuroscience↗

bioRxiv2019

White-nose syndrome restructures bat skin microbiomes

The skin microbiome is an essential line of host defense against pathogens, yet our understanding of microbial communities and how they change when hosts become infected is limited. We investigated skin microbial composition in three North American bat species (Myotis lucifugus, Eptesicus fuscus, and Perimyotis subflavus) that have been impacted by the infectious disease, white-nose syndrome, caused by an invasive fungal pathogen, Pseudogymnoascus destructans. We compared bacterial and fungal composition from 154 skin swab samples and 70 environmental samples using a targeted 16S rRNA and ITS amplicon approach. We found that for M. lucifugus, a species that experiences high mortality from white-nose syndrome, bacterial microbiome diversity was dramatically lower when P. destructans is present. Key bacterial families--including those potentially involved in pathogen defense--significantly differed in abundance in bats infected with P. destructans compared to uninfected bats. However, skin bacterial diversity was not lower in E. fuscus or P. subflavus when P. destructans was present, despite populations of the latter species declining sharply from white-nose syndrome. The fungal species present on bats substantially overlapped with the fungal taxa present in the environment at the site where the bat was sampled, but fungal community composition was unaffected by the presence of P. destructans for any of the three bat species. This species-specific alteration in bat skin bacterial microbiomes after pathogen invasion may suggest a mechanism for the severity of WNS in M. lucifugus, but not for other bat species impacted by white-nose syndrome.

microbiology↗

bioRxiv2019

Field trial of a probiotic bacteria and a chemical, chitosan, to protect bats from white-nose syndrome

Tools for reducing wildlife disease impacts are needed to conserve biodiversity. White-nose syndrome (WNS), caused by the fungus Pseudogymnoascus destructans, has caused widespread declines in North American bat populations and threatens several species with extinction. Few tools exist for managers to reduce WNS impacts. We tested the efficacy of two treatments, a probiotic bacterium, Pseudomonas fluorescens, and a chemical, chitosan, to reduce impacts of WNS in two simultaneous experiments conducted with caged and free-flying Myotis lucifugus bats at a mine in Wisconsin, USA. In the free-flying experiment, treatment with P. fluorescens increased apparent overwinter survival five-fold compared to the control group (from 8.4% to 46.2%) by delaying emergence of bats from the site by 30 days. Apparent overwinter survival for free-flying chitosan-treated bats was 18.0%, which did not differ significantly from control bats. In the cage experiment, chitosan-treated bats had significantly higher survival until release on March 8 (53%) than control and P. fluorescens-treated bats (both 27%). However, these differences were likely due to within-cage disturbance and not reduced WNS impacts, because chitosan-treated bats actually had significantly higher UV-fluorescence (a measure of disease severity), and body mass, not infection intensity, predicted mortality. Further, few of the bats released from the cage experiment were detected emerging from the mine, indicating that the survival estimates at the time of release did not carryover to overwinter survival. These results suggest that treatment of bats may reduce WNS mortality, but additional measures are needed to prevent declines.

ecology↗