Biology subjects

Pages, N.

Publications and source records attributed to Pages, N..

4 recordsLinked to original sources

bioRxiv2025

Dissection and internal observation of the giant tropical bont tick Amblyomma variegatum

Ticks are parasites arthropods that feed on the blood of animals and humans, serving as vectors responsible for numerous diseases worldwide. The tropical bont tick, Amblyomma variegatum, is the primary vector of Ehrlichia ruminantium, the causative agent of heartwater, endemic in sub-Saharan and southern Africa and several Caribbean islands. Due to their economic and public health impacts, A. variegatum and heartwater have been classified as high-consequence foreign animal diseases and pests by the United States Department of Agricultures Animal and Plant Health Inspection Service. Understanding the ecology and biology of A. variegatum is thus crucial to describe the tick-bacteria interactions and thus developing effective control methods. A key initial step in this endeavor involves the precise isolation and detailed functional characterization of tick organs to better understand vector competence. However, complete anatomical descriptions of internal structures within the Amblyomma genus remain scarce. In this study, we present a thorough characterization of the internal anatomy of A. variegatum. By accurately identifying and mapping organs of interest, we highlight notable morphological differences from other tick species. This work not only enhances our understanding of A. variegatum anatomy but also serves as a crucial resource for investigating tick-borne disease transmission. Ultimately, these findings support the development of targeted vector control strategies, applicable to both endemic and non-endemic regions.

zoology↗

bioRxiv2025

Caribbean octocoral communities: finding the forest for the trees?

Octocorals have increased in abundance on many Caribbean coral reefs, and at some sites "octocoral forest" may be a better community descriptor than "coral reef." Implicit to the concept of a forest is that structural elements, trees, colonies, etc., alter the environment in ways that affect the structural elements themselves and the organisms that inhabit the forest. At what density do the structural elements create the emergent properties of a "forest?" Communities traditionally characterized as hardgrounds and coral reefs around Puerto Rico and St John, US Virgin Islands, varied in density of octocoral colonies from a few to >100 colonies m-2in surveys conducted in 2021 and 2022. Canopy cover was correlated with the density of colonies. Among the quadrats with the highest octocoral density there was no significant correlation between numbers of colonies and canopy cover. Frontal area, a measure related to the communitys effect on water flow, as well as the volume occupied by colonies followed patterns similar to canopy cover. Vertical profiles of flow velocity were measured from the substratum to 3 m above the bottom on a reef on St John where octocoral population density ranged from 0 to 16 colonies m-2. Profiles of orbital velocity exhibited perturbations which were more pronounced in locations with > 12 colonies m-2. Using the effect on flow as a criterion, 4 of the 8 surveyed sites would function as forests. Understanding the density at which emergent properties appear is critical to understanding the bio-physical interactions affecting the community.

ecology↗

bioRxiv2022

pWCP is a widely distributed and highly conserved Wolbachia plasmid in Culex mosquitoes worldwide

Mosquitoes represent the most important pathogen vectors and are responsible for the spread of a wide variety of poorly treatable diseases. Wolbachia are obligate intracellular bacteria that are widely distributed among arthropods and collectively represents one of the most promising solutions for vector control. In particular, Wolbachia has been shown to limit the transmission of pathogens, and to dramatically affect the reproductive behavior of their host through its phage WO. While much research has focused on deciphering and exploring the biocontrol applications of these WO-related phenotypes, the extent and potential impact of the Wolbachia mobilome remain poorly appreciated. Notably, several Wolbachia plasmids, carrying WO-like genes and Insertion Sequences (IS), thus possibly interrelated to other genetic units of the endosymbiont, have been recently discovered. Here we investigated the diversity and biogeography of the first described plasmid of Wolbachia in Culex pipiens (pWCP) in several islands and continental countries around the world--including Cambodia, Guadeloupe, Martinique, Thailand, and Mexico--together with mosquito strains from colonies that evolved for 2 to 30 years in the laboratory. Together with earlier observation, our results show that pWCP is omnipresent and strikingly conserved among Wolbachia populations within mosquitoes from distant geographies and environmental conditions. These data suggest a critical role for the plasmid in Wolbachia ecology and evolution, and the potential of a great tool for the further genetic dissection or potential manipulation of the endosymbiont.

microbiology↗

bioRxiv2021

The mosquito microbiome includes habitat-specific but rare symbionts

Microbial communities are known to influence mosquito lifestyles by modifying essential metabolic and behavioral processes that affect reproduction, development, immunity, digestion, egg survival, and ability to transmit pathogens. Many studies have used 16S rRNA gene amplicons to characterize mosquito microbiota and investigate factors that influence host-microbiota dynamics. However, a relatively low taxonomic resolution due to clustering methods based on arbitrary threshold and the overall dominance of Wolbachia or Asaia populations obscured the investigation of rare members of mosquito microbiota in previous studies. Here, we used high resolution Shannon entropy-based oligotyping approaches to analyze the microbiota of Culex pipiens, Culex quinquefasciatus and Aedes individuals from continental and overseas regions in Southern France and Guadeloupe as well as from laboratories with or without antibiotics treatment. Our experimental design that resulted in a series of mosquito samples with a gradient of Wolbachia density and relative abundance along with high-resolution analyses of amplicon sequences enabled the recovery of a robust signal from typically less accessible bacterial taxa. Our data confirm species-specific mosquito-bacteria associations with geography as a primary factor that influences bacterial community structure. But interestingly, they also reveal co-occurring symbiotic bacterial variants within single individuals for both Elizabethkingia and Erwinia genera, distinct and specific Asaia and Chryseobacterium in continental and overseas territories and a putative rare Wolbachia variant. Overall, our study reveals the presence of previously-overlooked microdiversity and multiple closely related symbiotic strains within mosquito individuals with a remarkable habitat-specificity.

microbiology↗