Biology subjects

Scolari, F.

Publications and source records attributed to Scolari, F..

6 recordsLinked to original sources

bioRxiv2026

Widespread SARS-CoV-2 infection in free-ranging Neotropical bats suggests repeated human-to-bat spillback

Bats harbor exceptional coronavirus diversity and are considered ancestral sources of several human pathogens. As SARS-CoV-2 transitioned from pandemic emergence to global endemicity in humans, concern has shifted from wildlife-to-human spillover toward reverse zoonosis. However, infection of free-ranging bat populations under natural conditions has not previously been demonstrated. Here, we report widespread detection of SARS-CoV-2 RNA in wild Neotropical bats sampled across Andean and Amazonian ecosystems of Southern Ecuador. RT-qPCR screening of 126 individuals, representing nine taxa, detected SARS-CoV-2 RNA in 34.12% of bats across multiple sites. Partial to near-complete viral genomes recovered from five individuals showed >99% nucleotide identity to contemporary human SARS-CoV-2 lineages and clustered within multiple global phylogenetic clades. Mixed-effects modeling revealed pronounced species-level heterogeneity, a positive association between elevation and infection probability, and higher infection probability in females compared with males. The close phylogenetic affinity of bat-derived genomes to circulating human variants and their distribution across multiple lineages suggest repeated anthropogenic spillback rather than sustained bat-specific circulation. These results expand current understanding of the ecological footprint of the COVID-19 pandemic and highlight the importance of integrating wildlife surveillance into long-term One Health strategies for emerging infectious diseases.

microbiology↗

bioRxiv2025

Endosymbiont hijacking of acylcarnitines regulates insect vector fecundity by suppressing the viability of stored sperm

Competition between insects and their endosymbiotic bacteria for environmentally limited nutrients can compromise the fitness of both organisms. Tsetse flies, the vectors of pathogenic African trypanosomes, harbor a species and population-specific consortium of vertically transmitted endosymbiotic bacteria that range on the functional spectrum from mutualistic to parasitic. Tsetses indigenous microbiota can include a member of the genus Spiroplasma, and infection with this bacterium causes fecundity-reducing phenotypes in the fly that include a prolonged gonotrophic cycle and a reduction in the motility of stored spermatozoa post-copulation. Herein we demonstrate that Spiroplasma and tsetse spermatozoa compete for fly-derived acylcarnitines, which in other bacteria and animals are used to maintain cell membranes and produce energy. The fat body of mated female flies increases acylcarnitine production in response to infection with Spiroplasma. Additionally, their spermathecae (sperm storage organs), and likely the sperm within, up-regulate expression of carnitine O-palmitoyltransferase-1, which is indicative of increased acylcarnitine metabolism and thus increased energy demand and energy production in this organ. These compensatory measures are insufficient to rescue the motility defect of spermatozoa stored in the spermathecae of Spiroplasma-infected females and thus results in reduced fly fecundity. Tsetses taxonomically simple and highly tractable indigenous microbiota make the fly an efficient model system for studying the biological processes that facilitate the maintenance of bacterial endosymbioses, and how these relationships impact conserved mechanisms (mammalian spermatozoa also use acylcarnitines as an energy source) that regulated animal host fecundity. In the case of insect pests and vectors, a better understanding of the metabolic mechanisms that underlie these associations can lead to the development of novel control strategies. Author SummaryAnimals and the endosymbiotic bacteria that live inside them often compete for nutrients that both organisms require in order to survive. Tsetse flies, which transmit pathogenic African trypanosomes, can house several endosymbionts that have different impacts on their hosts physiological well-being. Female tsetse flies that are infected with one of these bacteria, Spiroplasma, produce fewer offspring than do their uninfected counterparts. In this study we demonstrate that the bacterium and the flys sperm cells (spermatozoa) compete for a specific type of lipid called acylcarnitines. When mated female tsetse flies are experimentally manipulated to produce less acylcarnitine Spiroplasma density decreases. Additionally, spermatozoa stored in the sperm storage organs of acylcarnitine depleted females lose motility and are eventually resorbed, thus rendering the females reproductively sterile. These findings mechanistically demonstrate how endosymbiotic bacteria can manipulate their hosts reproductive potential. In the case of arthropods that transmit pathogenic microbes, this relationship has significant implications for disease transmission and epidemiology.

microbiology↗

bioRxiv2022

Lipid metabolism dysfunction following symbiont elimination is linked to altered Kennedy pathway homeostasis

Lipid metabolism is critical for insect reproduction, especially for species that invest heavily into early developmental stages of their offspring. The role of symbiotic bacteria during this process is unknown but likely essential, especially in the case of obligate microbes that fulfill key biological functions in the host. Using a combined lipidomics, functional genomics and biochemical strategy, we examined the role of lipid metabolism in the interaction between the viviparous tsetse fly (Glossina morsitans morsitans) and its obligate endosymbiotic bacteria (Wigglesworthia glossinidia) during tsetse pregnancy. We observed increased CTP:phosphocholine cytidylyltransferase (cct1) expression during pregnancy. This gene codes for the enzyme that functions as the rate limiting step in phosphatidylcholine biosynthesis in the Kennedy pathway which is critical for stored lipid metabolism and progeny development. Experimental removal of Wigglesworthia impaired lipid metabolism via disruption of the Kennedy pathway, yielding obese mothers whose developing progeny ultimately starve. Functional validation via experimental cct1 suppression revealed a phenotype similar to females lacking obligate Wigglesworthia symbionts. These results indicate that, in Glossina, symbiont-derived factors, likely B vitamins, are critical for proper function of both lipid biosynthesis and lipolysis. Loss of the symbiosis has a dramatic impact on Glossina fecundity, and may be broadly applicable to other insect systems, particularly to species that require symbiotic partners to maximize lipolysis and reproductive output.

physiology↗

bioRxiv2019

Maleness-on-the-Y (MoY) orchestrates male sex determination in major agricultural fruit fly pests

In insects, rapidly evolving primary sex-determining signals are transduced by a conserved regulatory module producing sex-specific proteins that direct sex determination and sexual differentiation1-4. In the agricultural pest Ceratitis capitata (medfly), a Y-linked maleness factor (M) is thought to repress the autoregulatory splicing of transformer (Cctra), which is required in XX individuals to establish and maintain female sex determination5,6. Despite previous attempts of isolating Y-linked genes using the medfly whole genome, the M factor has remained elusive7. Here, we report the identification of a Y-linked gene, Maleness-on the-Y (MoY), and show that it encodes a small novel protein which is both necessary and sufficient for medfly male sex determination. Transient silencing of MoY in XY individuals leads to the development of fertile females while transient expression of MoY in XX individuals results in fertile males. Notably, a cross between these sex reverted individuals gives rise to both fertile males and females indicating that a functional MoY can be maternally transmitted. In contrast to the diversity of M factors found in dipteran species8-11, we discovered MoY orthologues in seven other Tephritid species spanning [~]111 millions of years of evolution (Mya). We confirmed their male determining function in the olive fly (Bactrocera oleae) and the oriental fruit fly (Bactrocera dorsalis). This unexpected conservation of the primary MoY signal in a large number of important agricultural pests12 will facilitate the development of transferable genetic control strategies in these species, for example sterile male releases or sex-ratio-distorting gene drives.

genetics↗

bioRxiv2019

The Glossina Genome Cluster: Comparative Genomic Analysis of the Vectors of African Trypanosomes

BackgroundTsetse flies (Glossina sp.) are the sole vectors of human and animal trypanosomiasis throughout sub-Saharan Africa. Tsetse are distinguished from other Diptera by unique adaptations, including lactation and the birthing of live young (obligate viviparity), a vertebrate blood specific diet by both sexes and obligate bacterial symbiosis. This work describes comparative analysis of six Glossina genomes representing three sub-genera: Morsitans (G. morsitans morsitans (G.m. morsitans), G. pallidipes, G. austeni), Palpalis (G. palpalis, G. fuscipes) and Fusca (G. brevipalpis) which represent different habitats, host preferences and vectorial capacity. ResultsGenomic analyses validate established evolutionary relationships and sub-genera. Syntenic analysis of Glossina relative to Drosophila melanogaster shows reduced structural conservation across the sex-linked X chromosome. Sex linked scaffolds show increased rates of female specific gene expression and lower evolutionary rates relative to autosome associated genes. Tsetse specific genes are enriched in protease, odorant binding and helicase activities. Lactation associated genes are conserved across all Glossina species while male seminal proteins are rapidly evolving. Olfactory and gustatory genes are reduced across the genus relative to other characterized insects. Vision associated Rhodopsin genes show conservation of motion detection/tracking functions and significant variance in the Rhodopsin detecting colors in the blue wavelength ranges. ConclusionsExpanded genomic discoveries reveal the genetics underlying Glossina biology and provide a rich body of knowledge for basic science and disease control. They also provide insight into the evolutionary biology underlying novel adaptations and are relevant to applied aspects of vector control such as trap design and discovery of novel pest and disease control strategies.

genomics↗

bioRxiv2018

Evolutionary landscape of mosquito viral integrations

The sequenced genome of the arboviral vector mosquito, Aedes albopictus, is replete with repetitive DNA and it harbors an unusually large number of endogenous viral sequences, collectively called Nonretroviral Integrated RNA Virus Sequences (NIRVS). NIRVS are enriched both within protein-coding gene exons and PIWI-interacting RNA (piRNA) clusters, where they encode piRNAs. Based on these features, NIRVS have been proposed to function as novel mosquito antiviral immune factors. However, the relative importance and contributions of different NIRVS as functional antiviral elements and their mechanisms of action remain open questions.\n\nWe apply an analytical approach that intersects computational, evolutionary and molecular methods to identify NIRVS most likely affecting mosquito immunity. Using this strategy, we show that NIRVS are a highly dynamic component of the Ae. albopictus repeatome, which nevertheless maintains a core set of seemingly the oldest NIRVS with similarity to Rhabdoviruses. Population-level polymorphism of NIRVS varies depending on whether they occur in intergenic regions, piRNA clusters or are part of gene exons. NIRVS from piRNA clusters are differentially widespread in diverse populations but conserved at the sequence level. This is consistent with the hypothesis that they act analogously to fragments of transposable elements in piRNA clusters and contribute to piRNA-based immunity. Among NIRVS from gene exons, AlbRha52 and AlbRha12 have the hallmarks of domestication as they are fixed across populations, stably expressed, and as polymorphic at the sequence level as fast-evolving genes. Overall these results support the hypothesis that NIRVS contribute to mosquito immunity, potentially through diverse modes of action.

evolutionary biology↗