Geology Reports⌕ Search
Home/Archive/USGS

USGS · 1014241

Thin-section electron microscopy of mature Myxosoma cerebralis (Myxosporidea) spores

P.D. Lunger·B.L. Rhoads·K. Wolf·M.E. Markiw
View original source ↗Export metadata ↓

Abstract

The morphology of purified, mature Myxosoma cerebralis spores was examined by thin-section electron microscopy. Surface architecture corresponded closely to that described in an earlier scanning electron microscopy study of this organism (Lom and Hoffman, 1971). A uniformly thick spore wall is composed of finely granular, electron-lucent material. Intrawall "valvoplasm" at the sutural border region contains small, light spheroidal profiles with dense centers situated in a background matrix; such structures are absent in the intermediate wall areas. Ovoid polar capsules contain complex filamentous profiles within the peripheral matrix region. Individual filaments appear twisted into S-shaped configurations and contain moderately electron-opaque material within their lumina.

Explore related subjects

Journal of ParasitologyArticle

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

P.D. Lunger, B.L. Rhoads, K. Wolf, M.E. Markiw. 1975. Thin-section electron microscopy of mature Myxosoma cerebralis (Myxosporidea) spores. https://doi.org/10.2307/3279327

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2025

Two new species of Henneguya Thélohan, 1892 (Cnidaria: Bivalvulida: Myxobolidae) infecting gill of blue catfish, Ictalurus furcatus (Rafinesque) (Siluriformes: Ictaluridae) from the Tallapoosa River and Chesapeake Bay tributaries

We herein describe 2 new species of Henneguya Thélohan, 1892 (Bivalvulida: Myxobolidae), Henneguya auburnensis Ksepka and Bullard n. sp. and Henneguya chesapeakensis Ksepka, Walsh, and Bullard n. sp., infecting the inter-lamellar epithelium of cultured blue catfish ( Ictalurus furcatus [Valenciennes, 1840] [Siluriformes: Ictaluridae]) from Saugahatchee Creek (Tallapoosa River; Auburn, Alabama) and the inter-lamellar epithelium of invasive blue catfish captured in Chesapeake Bay tributaries, respectively. Henneguya auburnensis resembles Henneguya mississippiensis Rosser, Griffin, Quiniou, Khoo, Greenway, Wise, and Pote, 2015 , and Henneguya sutherlandi Griffin, Pote, Wise, Greenway, Mauel, and Camus, 2008 , which both infect channel catfish ( Ictalurus punctatus [Rafinesque, 1818] [Siluriformes: Ictaluridae]) in Mississippi, but differs from these species by having more polar tubule coils (10–12 vs. 8–9 and 6, respectively). Henneguya chesapeakensis resembles Henneguya longicauda Minchew, 1977 , which infects channel catfish in Mississippi, but differs from this species by having shorter polar capsules (6.0–7.0 vs. 7.0–9.0). A phylogenetic analysis of the small subunit (SSU) rDNA recovered ictalurid-infecting Henneguya spp. as monophyletic, with H. auburnensis sister to a clade of Henneguya spp. that, except for H. chesapeakensis , infect the gill or adipose fin of channel catfish. Henneguya chesapeakensis was recovered sister to Henneguya ictaluri Pote, Hanson, and Shivaji, 2000 . Histological sections of infected gill filaments revealed that the plasmodia of both new species developed within the inter-lamellar epithelium. The new species comprise the second and third species of Henneguya reported from blue catfish.

Journal of Parasitology↗
USGS2024

Abiotic and demographic drivers of flea parasitism on deer mice in a recovering mixed-conifer forest a decade postfire

With the intensity and frequency of wildfires increasing rapidly, the need to study the ecological effects of these wildfires is also growing. An understudied aspect of fire ecology is the effect fires have on parasite–host interactions, including ectoparasites that might be pathogen vectors. Although some studies have examined the impacts of fire on ticks, studies on other ectoparasites, including pathogen vectors, are rare. To help address this knowledge gap, we examined the abiotic and biotic factors that predict the likelihood and extent of parasitism of deer mice ( Peromyscus maniculatus ) by fleas within a landscape of unburned and recovering burned (>9 yr postfire) mixed conifer forests. We sampled 227 individual deer mice across 27 sites within the Jemez Mountains of northern New Mexico in 2022 and quantified measures of parasitism by fleas (primarily Aetheca wagneri ). These sites were distributed in both unburned areas (n = 15) and recovering burned areas (n = 12), with the latter derived from 2 large fires, the Las Conchas fire (2011) and the Thompson Ridge fire (2013). Using these data, we tested for differences in prevalence, mean abundance, and mean intensity of fleas on deer mice, focusing on the predictive importance of host sex and fire history. We also created generalized linear mixed-effects models to investigate the best host and environmental predictors of parasitism by fleas. Approximately a decade postfire, we found minimal evidence to suggest that fire history influenced either the presence or intensity of fleas on deer mice. Rather, at the current forest-regeneration stage, the extent of parasitism by fleas was best predicted by measures of host sex, body condition, and the trapline's ability to accumulate water, as measured through topography. As host body condition increased, the probability of males being parasitized increased, whereas the opposite pattern was seen for females. Male mice also had significantly greater flea loads. Among potential abiotic predictors, the topographic wetness index or compound topographic index (a proxy for soil moisture) was positively related to flea intensity, suggesting larger flea populations in burrows with higher relative humidity. In summary, although fire may potentially have short-term impacts on the likelihood and extent of host parasitism by fleas, in this recovering study system, host characteristics and topographic wetness index are the primary predictors of parasitism by fleas.

New Mexico↗
USGS2022

Detection of Splendidofilaria sp. (Onchocercidae:Splendidofilariinae) Microfilaria within Alaskan ground-dwelling birds in the grouse subfamily tetraoninae using taqman probe-based real-time PCR

Grouse and ptarmigan (Galliformes) harbor fairly diverse helminth faunas that can impact the host's health, including filarial nematodes in the genus Splendidofilaria . As host and parasite distributions are predicted to shift in response to recent climate change, novel parasites may be introduced into a region and impose additional stressors on bird populations. Limited information is available on the prevalence of filariasis in Alaska galliforms. To date, no molecular surveys have been completed. Past studies relied on examining blood smears or total body necropsies, which are time-consuming and may not detect filarial parasites with low prevalence in hosts. Therefore, we developed a TaqMan probe-based real-time PCR assay targeting the cytochrome c oxidase 1 gene ( COI ) of Splendidofilaria to decrease processing times and increase sensitivity as well as provide baseline data on the diversity of filariid infections in galliform species in Alaska. We screened a combined total of 708 galliform samples (678 unique individual birds) from different tissues (blood, muscle, and lung) for the presence of filarial DNA across the state of Alaska. Real-time PCR screening revealed an overall prevalence of filarial infection of 9.5% across species: Bonasa umbellus (0%, n = 23), Dendragapus fuliginosus (0%, n = 8), Falcipennis canadensis (26.8%, n = 198), Lagopus lagopus (2.6%, n = 274), Lagopus leucura (0%, n = 23), Lagopus muta (3%, n = 166), and Tympanuchus phasianellus (12.5%, n = 16). We observed microfilarial infections throughout most of Alaska except in Arctic regions and the Aleutian Islands where viable vectors may not be present.

Journal of Parasitology↗