Biology subjects

Spear, J.

Publications and source records attributed to Spear, J..

7 recordsLinked to original sources

bioRxiv2025

Molecular insights into phycobilisome assembly pathway reveal crystalline bodies in cyanobacteria

In oxygenic photosynthetic organisms, light energy is converted to chemical energy to drive CO2 fixation reactions and sustain life on Earth. Cyanobacteria contain phycobilisome (PBS) complexes that play critical roles in light harvesting and directing light energy to the photosystem I and II reaction centers. The proper assembly of PBS components is an intricate process that is required for their activity and association with photosystem I and II. To understand the complex mechanisms regulating the PBS assembly, we knocked out the terminal emitter apcE, which forms the structural scaffold for the PBS core. ApcE knockout led to growth and pigment defects, including elevated levels of photosystem II and abnormal emission spectra. Light microscopy experiments revealed the accumulation of highly fluorescent puncta localized to the pole of apcE knockout cells. Further investigation using electron cryo-tomography identified highly repetitive crystalline arrays of densely packed PBS cylinders. Together, these data indicate that cyanobacteria may accumulate PBS components in the form of highly organized crystalline bodies as intermediates during PBS assembly.

microbiology↗

bioRxiv2025

Genetic surveillance of Plasmodium-Anopheles compatibility markers during Anopheles stephensi associated malaria outbreak

Despite previous decline of malaria in Ethiopia, an outbreak in Dire Dawa in 2022 implicated invasive vector An. stephensi as responsible. The transmission of Plasmodium by invasive An. stephensi raises questions about the molecular basis of compatibility, and the origin of the Plasmodium being transmitted. The Plasmodium P47 gene is a parasite-vector interaction gene in Anopheles, and along with corresponding mosquito P47 receptor (P47Rec), can be critical in establishment of Plasmodium infections in anophelines. Here, we analyzed P47 and P47Rec sequences to determine the origin of Plasmodium detected in An. stephensi during the outbreak and evaluate markers of compatibility. Analysis of geographically informative SNPs in Pfs47 revealed that these P. falciparum exhibit the African haplotype. We also identified a single amino acid change in P47Rec within these An. stephensi, which could act as a marker for the propensity of An. stephensi populations to outbreaks. Together, we provide the basis for further study to deepen the understanding of invasive An. stephensi -African Plasmodium interactions to better control transmission of malaria and prevent further outbreaks.

evolutionary biology↗

bioRxiv2023

A regional One Health approach to the risk of invasion by Anopheles stephensi in Mauritius

BackgroundAnopheles stephensi is an invasive malaria vector in Africa that threatens to put an additional 126 million people at risk of malaria if it continues to spread. The island nation of Mauritius is highly connected to Asia and Africa and is at risk of introduction due to this connectivity. For early detection of An. stephensi, the Vector Biology and Control Division under the Ministry of Health in Mauritius, leveraged a well-established Aedes program, as An. stephensi is known to share Aedes habitats. These efforts triggered multisectoral coordination and cascading benefits of integrated vector and One Health approaches. MethodsBeginning June 2021, entomological surveys were conducted at points of entry (seaport, airport) and on ships transporting livestock in collaboration with the Civil Aviation Department, the Mauritian Port Authority and National Veterinary Services. A total of 39, 18, 723 mosquito larval surveys were respectively conducted in the seaport, airport and other localities in Mauritius while 20, two and 26 adult mosquito surveys were respectively conducted in the seaport, airport and twenty-six animal points. Alongside adult mosquito surveys, surveillance of vectors of veterinary importance (e.g.- licoides spp.) was also carried out in collaboration with National Parks and Conservation Service and land owners. ResultsA total of 8,428 adult mosquitoes were collected and 1,844 larval habitats were positive for mosquitoes. All collected mosquitoes were morphologically identified and 151 Anopheles and 339 Aedes mosquitoes were also molecularly characterized. Mosquito species detected were Aedes albopictus, Anopheles arabiensis, An. coustani, An. merus, Culex quinquefasciatus, Cx. thalassius and Lutzia tigripes. Anopheles stephensi was not detected. The One Health approach was shared with the French Agricultural Research Centre for International Development (CIRAD), strengthening collaboration between Mauritius and Reunion Island on vector surveillance at entry points and insecticide resistance monitoring. The Indian Ocean Commission (IOC) was also alerted to the risk of An. stephensi, leading to regional efforts supporting trainings and development of a response strategy to An. stephensi bringing together stakeholders from Comoros, Madagascar, Mauritius, Reunion Island and Seychelles. ConclusionsMauritius is a model system showing how existing public health entomology capabilities can be used to enhance vector surveillance and control and create multisectoral networks to respond to any emerging public and veterinary health vector-borne disease threat. Author summaryThe malaria mosquito, Anopheles stephensi, is invasive in Africa where it threatens to put an additional 126 million people at risk of malaria if it continues to spread throughout the continent. The island nation of Mauritius is highly connected to Asia and Africa through maritime trade and therefore may be at risk of An. stephensi introduction and establishment. Mauritius implemented a One Health approach, enhancing entomological surveillance at entry points and collaborating across sectors (e.g. veterinary services, sea and air port authorities, national parks and conservation, communities, etc.) conducted extensive integrated vector surveillance, inspecting 85,071 larval habitats, and analyzing 8,428 adult mosquitoes morphologically and molecularly. Although An. stephensi was not detected, the initiative catalyzed and strengthened multisectoral partnerships nationally and across the Indian Ocean region member states (Comoros, Madagascar, Mauritius, Reunion Island and Seychelles). Leveraging the threat of An. stephensi, Mauritius exemplifies utilizing existing capabilities to create multisectoral networks for effective vector surveillance and response.

ecology↗

bioRxiv2021

Tracking of Anopheles stephensi in Ethiopia using mitochondrial DNA reveals pattern of spread

The recent detection of the South Asian malaria vector Anopheles stephensi in the Horn of Africa (HOA) raises concerns about the impact of this mosquito on malaria transmission in the region. The mode and history of introduction is important for predicting the likelihood of continued introduction and future spread. Analysis of An. stephensi genetic diversity and population structure can provide insight into the history of the mosquito in the HOA. We investigated genetic diversity of An. stephensi in eastern Ethiopia where detection suggests a range expansion to this region to understand the history of this invasive population. We sequenced the cytochrome oxidase subunit I (COI) and cytochrome B gene (CytB) in 187 An. stephensi collected from 10 sites in Ethiopia in 2018. Phylogenetic analyses using a maximum-likelihood approach and minimum spanning network were conducted for Ethiopian sequences. Molecular identification of bloodmeal sources was also performed using universal vertebrate CytB sequencing. Six COI-CytB haplotypes were observed based on five segregating sites, with the highest number of haplotypes in the northeastern sites (Semera, Bati, and Gewana towns) relative to the southeastern sites (Kebridehar, Godey, and Degehabur) in eastern Ethiopia. In the phylogenetic and network analysis, we observed population differentiation based on the distribution of the haplotypes across the northeastern and central sites (Erer Gota, Dire Dawa, and Awash Sebat Kilo) compared to the southeastern sites and evidence of a South Asian origin of the HOA An. stephensi lineages. The presence of the putative South Asian haplotype of origin at sites closest to Ethiopias northeastern borders support route of introductions into Ethiopia from the northeast. Finally, molecular bloodmeal analysis revealed evidence of feeding on bovines, goats, dogs, and humans, as well as evidence of multiple (mixed) blood meals. In conclusion, we find support for the hypothesis for the recent expansion of An. stephensi into southeastern Ethiopia with multiple introductions. We also find evidence that supports the hypothesis that HOA An. stephensi populations originate from South Asia rather than the Arabian Peninsula. The evidence of both zoophagic and anthropophagic feeding support the potential for livestock movement to play a role in vector spread in this region.

ecology↗

bioRxiv2019

Geographical distribution of Anopheles stephensi in eastern Ethiopia

BackgroundThe recent detection of the South Asian malaria vector An. stephensi in Ethiopia and other regions in the Horn of Africa has raised concerns about its potential impact on malaria transmission. We report here findings of survey for this species in eastern Ethiopia using both morphological and molecular methods for species identification.\n\nMethodsAdult and larval/pupal collections were conducted at ten sites in eastern Ethiopia and Anopheles specimens species were determined using standard morphological keys and genetic analysis.\n\nResultsIn total, 2,231 morphologically identified An. stephensi were collected. A molecular approach incorporating both PCR endpoint assay and sequencing of portions of the internal transcribed spacer 2 (ITS2) and cytochrome oxidase I (COI) loci confirmed the identity of the An. stephensi in most cases (119/124 of the morphologically identified An. stephensi confirmed molecularly). Additionally, we observed Aedes aegypti larvae and pupae at many of the An. stephensi larval habitats.\n\nConclusionsOur findings show that An. stephensi is widely distributed in eastern Ethiopia and highlight the need for further surveillance in the southern, western and northern parts of the country and throughout the Horn of Africa.

ecology↗

bioRxiv2019

Discrete Community Assemblages Within Hypersaline Paleolake Sediments of Pilot Valley, Utah

Hypersaline paleolake sediments are understudied ecosystems whose microbial ecology is largely unknown. Here we present mineralogical, geochemical, and small-subunit 16S rRNA gene sequence data on one such environment, the Pilot Valley Basin (PVB), a sub-basin of ancient Lake Bonneville located in northwest Utah. PVB exhibits a variety of aqueous minerals including phyllosilicates, carbonates, and sulfates, as well as microbially-induced sedimentary structures. As perchlorate occurs naturally (up to 6.5 ppb) in Pilot Valley sediments, and because recent evidence suggests that it is subject to biotic reduction, PVB has been proposed as a Mars analog site for astrobiological studies. 16S rRNA gene sequencing was used to investigate microbial diversity and community structure along horizontal and vertical transects within the upper basin sediments and beta diversity analyses indicate that the microbial communities in Pilot Valley are structured into three discrete groups. Operational taxonomic units (OTUs) belonging to the main archaeal phylum, Euryarchaeota, make up ~23% of the sequences, while OTUs belonging to three bacterial phyla, Proteobacteria, Bacteroides and Gemmatimonadetes, constitute ~60-70% of the sequences recovered at all sites. Diversity analyses indicate that the specific composition of each community correlates with sediment grain size, and with biogeochemical parameters such as nitrate and sulfate concentrations. Interestingly, OTUs belonging to the phylum Gemmatimonadetes are co-located with extreme halophilic archaeal and bacterial taxa, which suggests a potential new attribute, halophilicity, of this newly-recognized phylum. Altogether, results of this first comprehensive geomicrobial study of Pilot Valley reveal that basin sediments harbor a complex and diverse ecosystem.

microbiology↗

bioRxiv2017

BugBase Predicts Organism Level Microbiome Phenotypes

Shotgun metagenomics and marker gene amplicon sequencing can be used to directly measure or predict the functional repertoire of the microbiota en masse, but current methods do not readily estimate the functional capability of individual microorganisms. Here we present BugBase, an algorithm that predicts organism-level coverage of functional pathways as well as biologically interpretable phenotypes such as oxygen tolerance, Gram staining and pathogenic potential, within complex microbiomes using either whole-genome shotgun or marker gene sequencing data. We find BugBases organism-level pathway coverage predictions to be statistically higher powered than current bag-of-genes approaches for discerning functional changes in both host-associated and environmental microbiomes.

bioinformatics↗