Biology subjects

Cleveland, C. A.

Publications and source records attributed to Cleveland, C. A..

3 recordsLinked to original sources

bioRxiv2026

Global distribution of cultivated Trichodesmium subclades revealed by multi-omics

Trichodesmium is an important oceanic N2 fixing cyanobacterial genus that has been shown to provide up to 50% of new N to oligotrophic regimes. Despite its importance, we know relatively little about the genomic potential and functional diversity of the two major clades of Trichodesmium (Clade I and Clade III, hereafter Thieb and Tery, respectively). With the expanded collection of Trichodesmium isolates in the USCTCC (University of Southern California Trichodesmium Culture Collection), we sequenced genomes from seven cultivated strains to further characterize the genomic diversity within the genus. For example, sequencing the genome of the "gigantic", red Trichodesmium contortum surprisingly shows that they are closely related to the smallest Trichodesmium clade, TeryA. The high genomic identity between TeryA and T. contortum (>98.5% ANI) and lack of implicated auxiliary genes suggests their large biovolume differences might be transcriptional or epigenetic in origin. Furthermore, these data show that using Tery-subclades are a more accurate designation than the classical Trichodesmium species delineation. Finally, we placed the analysis of these genomes in an ecological context via read mapping with globally distributed RNA and DNA datasets. Our data show that Tery clades (A&B) are both lower in relative abundance compared to Thieb in global oceans, generally co-occur when detected in the field, and are highly linked to decreased salinity and increased temperatures, especially for sampling locations in the Bay of Bengal. Lastly, even though TeryA members are undersaturated with respect to current CO2 concentrations, our phenotypic and biogeography data suggests that salinity/ocean color could limit their predicted global impact as climate changes.

microbiology↗

bioRxiv2025

Comparative transcriptome profiles of first-stage larvae and adult female Dracunculus medinensis (Guinea worm)

Dracunculus medinensis, also called the Guinea worm, is a nematode that causes dracunculiasis, a debilitating neglected tropical disease in humans. The parasite is currently targeted by the global Guinea Worm Eradication Program (GWEP). Historically, GWEP in endemic countries have focused on interrupting transmission of the disease through intervention such as isolation and management of patients, health education, provision of improved water sources and promotion of filtering drinking water to avoid ingestion of the copepod intermediate host (IH) that may contain infectious third-stage larvae. The recent shift of Guinea worm infections in animals - particularly domestic dogs - has introduced an additional challenge to the eradication program, underscoring the urgent need for diagnostics and therapeutics. Understanding the parasite biology and survival strategies in the mammalian host, the copepod IH, and fresh water is pivotal to identifying new control measures. Comparative transcriptomic analysis provides a powerful tool to uncover the molecular mechanisms underlying parasite survival and adaptations. Here, we compared the transcriptome of adult gravid female and first-stage larvae (L1), the stage infective for the copepod IH. Comparative transcriptomic analysis of two adult females and their L1 revealed an upregulation of genes involved in translation, transcription, and DNA repair in L1, likely reflecting adaptations essential for survival in freshwater and subsequent infection of copepods. Additionally, genes involved in cuticle formation were upregulated in adult females highlighting the role of cuticle integrity in retaining millions of L1 until the gravid female worm emerges. We identified highly expressed genes in the adult female that may represent promising candidates for diagnostic markers. This study provides novel insights into the biology of the Guinea worm by examining the transcriptome of L1 and adult female stages. These findings could support the development of novel diagnostics and therapeutics to advance the ongoing eradication effort. Authors summaryGuinea worm disease is caused by the nematode Dracunculus medinensis, a parasitic worm responsible for a debilitating neglected tropical disease in humans and targeted for global eradication. Infection occurs through the consumption of contaminated drinking water with the infective larval stage harbored within fresh water crustacean copepods - the intermediate host of the parasite. The high number of Guinea worm infections in animals specially dogs poses a significant challenge to eradication, as infected animals act as reservoirs, contributing to the parasites persistence in the environment. Furthermore, the absence of early diagnostic tools and effective therapeutics complicates disease control. In this study, we performed a comparative transcriptome analysis of adult female Guinea worms and their first-stage larvae. We identified highly expressed genes in the adult female that may represent promising candidates for diagnostic markers. Additionally, we found genes and pathways upregulated in first-stage larvae which are likely essential for survival in freshwater and subsequent infection of copepods. Our study provides insight into the molecular mechanisms underlying Guinea worm survival across life stages and environments. These findings aim to support the development of novel diagnostics and therapeutics to advance ongoing eradication efforts of this neglected tropical disease.

genomics↗

bioRxiv2019

Population genomic evidence that human and animal infections in Africa come from the same populations of Dracunculus medinensis

BackgroundGuinea worm - Dracunculus medinensis - was historically one of the major parasites of humans and has been known since antiquity. Now, Guinea worm is on the brink of eradication, as efforts to interrupt transmission have reduced the annual burden of disease from millions of infections per year in the 1980s to only 30 human cases reported globally last year. Despite the enormous success of eradication efforts to date, one complication has arisen. Over the last few years, hundreds of dogs have been found infected with this previously apparently anthroponotic parasite, almost all in Chad. Moreover, the relative numbers of infections in humans and dogs suggests that dogs may be key in maintaining transmission in that country.\n\nResultsIn an effort to shed light on this peculiar epidemiology of Guinea worm in Chad, we have sequenced and compared the genomes of worms from dog, human and other animal infections. Confirming previous work with other molecular markers, we show that all of these worms are D. medinensis, and that the same population of worms are causing both infections, can confirm the suspected transmission between host species and detect signs of a population bottleneck due to the eradication efforts. The diversity of worms in Chad appears to exclude the possibility that there were no, or very few, worms present in the country during a 10-year absence of reported cases.\n\nConclusionsThis work reinforces the importance of adequate surveillance of both human and dog populations in the Guinea worm eradication campaign and suggests that control programs should stay aware of the possible emergence of unusual epidemiology as they approach elimination.

genomics↗