Biology subjects

Gutierrez, S.

Publications and source records attributed to Gutierrez, S..

15 recordsLinked to original sources

bioRxiv2025

Apparent failure and cryptic success of disease control via intermediate host population reduction: Density dependence in copepods has implications for Guinea worm disease transmission

All populations experience density dependence, lest they grow infinitely. However, elucidating what forms of density dependence act most strongly for a given species remains incredibly challenging. Identifying the mechanisms that regulate population density is particularly relevant to pest control, which often causes high mortality, reducing population density but enabling recovery when survivors are freed from intraspecific competition and density dependent vital rates (e.g., birth, death, and maturation rates). Understanding these demographic responses is critical for effective pest management, especially when specific life stages of pests differ in the harm they cause. Guinea worm disease (GWD) is a neglected tropical disease with an obligate copepod intermediate host, and importantly, only large-bodied copepods can be infected with GW parasites. GW disease has been the target of control for several decades, with main management strategies including the use of a chemical larvicide, Abate, which is applied to water bodies to cull copepod populations. Despite the wide application of Abate in GW endemic countries, little is known about long-term copepod population dynamics in response to Abate. Thus, we evaluated this mortality-based management of intermediate copepod hosts to control GW transmission, combining mathematical models with a population dynamics experiment designed to mimic Abate pesticide control methods across a range of intensities. Despite initial reductions in both total and stage specific population densities, copepod populations recovered so rapidly that control appeared to fail, enabled by extremely fast maturation rates in low-density populations. Much to our surprise, model simulations of GW transmission showed that although total and stage-specific densities rebounded, infectious adult copepods --the proximate cause of infections--were strongly suppressed, indicating cryptic success. This effect was enabled by the 15-day developmental period of GW larvae within copepods, which blocks the accumulation of infectious copepods between interventions. Ultimately, this study highlights the importance of understanding mechanisms of density dependence when designing and optimizing pest control interventions, as well as interpreting counterintuitive consequences of interventions.

ecology↗

bioRxiv2025

How an arthropod-borne virus manages host switches: exploration of host-specific mutations and gene formula in bluetongue virus

Arthropod-borne viruses, also known as arboviruses, cause disease worldwide. These viruses alternate between vertebrates and arthropods, facing distinct selection pressures in each host type. Surprisingly, whether specific mechanisms facilitate host alternation remains unclear. Here, we use bluetongue virus (BTV) as a model to investigate two phenomena potentially facilitating host alternation: adaptive mutations and genome formula variation (GFV). First, we searched for mutations indicative of host adaptation in cattle, sheep, and midges infected during an epizooty. We found a limited number of parallel mutations. This result suggests that adaptive mutations are not a main mechanism facilitating host alternation in BTV. Second, we investigated a link of GFV with a proxy of viral fitness, the speed of virus dissemination in midges. We analyzed the genome formula (GF) in experimentally-infected Culicoides imicola midges, either with an infection disseminated into the head or not. GFs differed between dissemination levels, suggesting a link between GF and the speed of virus dissemination. Finally, we investigated the mechanisms underlying GF generation. Currently, two scenarios have been proposed: random generation followed by selection, or directed generation through molecular mechanisms. To limit the influence of selection, we analyzed the GF after a single replication cycle in cell culture. GF values converged towards specific values among replicates. Moreover, GFs differed between arthropod and vertebrate cells. Thus, GF generation is not purely stochastic and is probably influenced by host-specific mechanisms. Overall, our findings highlight GFV as a potential mechanism facilitating BTV alternation across hosts, but not classical mutation-driven evolution. Author SummaryArthropod-borne viruses are important public health problems in the world. These viruses follow a complex cycle involving alternation between arthropods and vertebrates. Surprisingly, we know little on the mechanisms that facilitate alternation between the two host types. Knowledge on such mechanisms could allow the development of antiviral tools. Here, using Bluetongue virus as a model, we investigated two potential mechanisms facilitating alternation: adaptive mutations and genome formula variation (GFV). We found limited evidence for host-specific mutations in natural populations. We observed a potential link between GFV and viral fitness. Moreover, our results suggest that molecular mechanisms generate GFV in a host-specific way from the first round of cell infection.

microbiology↗

bioRxiv2024

Treatment with Metal-Organic Frameworks (MOFs) elicits secondary metabolite accumulation in Aquilaria crassna (Agarwood) callus culture

Thymelaceaous trees are prized for accumulating fragrant resins composed of hundreds of secondary metabolites in their woody tissues. Slow growth and increasing consumer demand have stretched natural sources of agarwood trees to being endangered and alternative production modes, including silviculture and tissue culture, are currently being investigated. Dedifferentiated tissue culture of agarwood trees provides a means of cell propagation independent of environmental context. However, secondary metabolite accumulation, as found in fragrant resins, occurs largely in response to wounding. Here, we investigated the application of metal-organic frameworks (MOFs) as potential elicitors of secondary metabolite formation in Aquilaria crassna tissue culture samples. Callus cultures were exposed to five commercially available MOFs: UiO-67, MOF-808, HKUST-1, ZIF-67, and MOF-74, and ethanol extracts were used to quantify secondary metabolite accumulation compared to untreated cultures. Samples that were exposed to Zr-based MOFs exhibited similar metabolite production profiles, (trans-2-Carboxy-cyclo-hexyl)-acetic acid was reduced in the presence of all MOFs, the Cu-containing HKUST-1 MOF increased palmitic acid levels, and MOF-808 and ZIF-67 were found to elicit the highest accumulation of secondary metabolites with potential fragrance applications. These results demonstrate the possibility of eliciting secondary metabolites from dedifferentiated agarwood tree cell culture and may provide an alternative means of sourcing fragrant specialty chemicals from these plants.

biochemistry↗

bioRxiv2024

Compartmentalized sesquiterpenoid biosynthesis and functionalization in the Chlamydomonas reinhardtii plastid

Terpenoids play key roles in cellular metabolism, with some organisms having evolved expanded terpenoid profiles for specialized functions such as signaling and defense. Many terpenoids have applications in pharmaceuticals, fragrances, and agriculture, but their harvest from natural sources can be challenging. Heterologous production of specialty terpenoids in microbial hosts offers an alternative, using terpene synthases and further enzymatic decoration to expand chemical complexity and functionality. Here, we explored the heterologous production of 10 different sesquiterpenoids (STPs, C15) and their further biofunctionalization mediated by cytochrome P450s (CYPs) in the green alga Chlamydomonas reinhardtii. STP synthases were expressed from the nuclear genome and localized to the algal plastid, coupled with co-expression of selected CYPs. STP production in the plastid was supported by farnesyl pyrophosphate synthase fusions to STP synthases, and CYPs were modified for soluble localization in the plastid stroma by removing transmembrane domains. Various target CYPs were screened for STP functionalization in the alga, and different product ratios were generated based on trophic modes. Overall STP yields ranged between 250-2500 {micro}g L-1 under screening conditions, with CYP-mediated functionalization reaching up to 80% of accumulated heterologous STP products. Living two-phase terpenoid extractions with different perfluorinated solvents revealed variable performances based on sesquiterpenoid functionalization and solvent type. This work demonstrates the feasibility of generating heterologous functionalized terpenoid products in alga using soluble, plastid-localized CYPs without reductase partners. However, overall improvements in photobioreactor cultivation concepts will be required to facilitate the use of algal chassis for scaled production. Significance StatementThis study demonstrates the feasibility of producing and modifying heterologous terpenoid products in the algal plastid using sesquiterpene synthases (STPS) and soluble cytochrome P450s (CYPs). We show that algal cultivation conditions influence the composition and ratios of functionalized terpenoid products, which can be extracted through solvent-based milking during growth. The reducing equivalents that enable CYP activity in the plastid appear derived from photosynthetic electrons without requiring the co-expression of a cytochrome P450 reductase (CPR) partner, simplifying engineering strategies. As algae can be cultivated with minimal inputs (trace elements, light, and CO2) from sources like wastewater, this approach offers the potential for sustainable production of complex specialty terpenoid chemicals.

bioengineering↗

bioRxiv2024

A metagenomics-based survey of the virus diversity in mosquito vectors allows the first detection of Sindbis virus in Burkina Faso

Mosquito-borne viruses represent a threat to human health worldwide. This taxonomically-diverse group includes numerous viruses that recurrently spread into new regions. Thus, periodic surveillance of the arbovirus diversity in a given region can help optimizing the diagnosis of arboviral infections. Nevertheless, such screenings are rarely carried out, especially in low-income countries. Consequently, case investigation is often limited to a fraction of the arbovirus diversity. This situation probably results in undiagnosed cases. Here, we have explored the diversity of mosquito-borne viruses in two regions of Burkina Faso. To this end, we have screened mosquitoes collected along three years in six urban and rural areas using untargeted metagenomics. The analysis focused on two mosquito species, Aedes aegypti and Culex quinquefasciatus, considered among the main vectors of arboviruses worldwide. The screening detected Sindbis virus (SINV, Togaviridae) for the first time in Burkina Faso. This zoonotic arbovirus has spread from Africa into Europe. SINV causes periodic outbreaks in Europe but its distribution and epidemiology in Africa remains largely unstudied. SINV was detected in one of the six areas of the study, and at a single year. Detection was validated with isolation in cell culture. SINV was only detected in Cx. quinquefasciatus, thus extending the list of potential vectors of SINV in nature. SINV infection rate in mosquitoes was similar to those observed in European regions that experience SINV outbreaks. A phylogenetic analysis placed the nearly-full genome within a cluster of Central African strains of lineage I. This cluster is supposedly at the origin of the SINV strains introduced into Europe. Thus, West Africa should also be considered as a potential source of the European SINV strains. Our results call for studies on the prevalence of SINV infections in the region to estimate disease burden and the interest of SINV diagnostic in case investigation. Author summaryMosquito-borne viruses are responsible for millions of cases worldwide every year. Moreover, they have repeatedly shown an ability to spread over large distances. Thus, periodic surveys of the arbovirus diversity in a given region can help to define the diagnostic tests to use during case investigation. However, comprehensive surveys are rarely carried out, especially in low-income countries. Here, the arbovirus diversity was assessed in two main mosquito vectors in Burkina Faso using untargeted metagenomics. This screening identified Sindbis virus (SINV), a zoonotic arbovirus, for the first time in Burkina Faso. Moreover, SINV was found in nature for the first time in Culex quinquefasciatus, a main mosquito vector of several pathogens and with a cosmopolitan distribution. SINV leads to periodic outbreaks mainly in Europe. Despite a likely African origin, its distribution and epidemiology in Africa remains largely unstudied. The SINV sequence from Burkina Faso felt within the cluster of Central African strains thought to be at the origin of the European SINV strains. Thus, our results indicate that West Africa should be considered as another potential source of the SINV introductions in Europe. Further studies are required to characterize SINV epidemiology in Burkina Faso and the West African region.

microbiology↗

bioRxiv2023

Host influence on the eukaryotic virome of sympatric mosquitoes and abundance of diverse viruses with a broad host range.

Mosquitoes harbor a large diversity of eukaryotic viruses. Those viromes probably influence mosquito physiology and the transmission of human pathogens. Nevertheless, their ecology remains largely unstudied. Here, we address two key questions in virome ecology. First, we assessed the influence of mosquito species on virome taxonomic diversity and relative abundance. Contrary to most previous studies, the potential effect of the habitat was explicitly included. Thousands of individuals of Culex poicilipes and Culex tritaeniorhynchus, two vectors of viral diseases, were concomitantly sampled in three habitats over two years. A total of 95 viral taxa from 25 families were identified with meta-transcriptomics, with 75% of taxa shared by both mosquitoes. Viromes significantly differed by mosquito species but not by habitat. Differences were largely due to changes in relative abundance of shared taxa. Then, we studied the diversity of viruses with a broad host range. We searched for viral taxa shared by the two Culex species and Aedes vexans, another disease vector, present in one of the habitats. Twenty-six out of the 163 viral taxa were found in the three mosquitoes. These taxa encompassed 14 families. A database analysis supported broad host ranges for many of those viruses, as well as a widespread geographical distribution. Thus, the viromes of mosquitoes from the same genera mainly differed in the relative abundance of shared taxa, whereas differences in viral diversity dominated between mosquito genera. Whether this new model of virome diversity and structure applies to other mosquito communities remains to be determined.

ecology↗

bioRxiv2023

A green alternative to fragrant agarwood sesquiterpenoid production

Certain endangered Thymelaeaceous trees are major sources of the fragrant and highly valued resinous agarwood, comprised of hundreds of oxygenated sesquiterpenoids (STPs). Despite growing pressure on natural agarwood sources, the chemical complexity of STPs severely limits synthetic production. Here, we catalogued the chemical diversity in 58 agarwood samples by two-dimensional gas chromatography-mass spectrometry and partially recreated complex STP mixtures through synthetic biology. We improved STP yields in the unicellular alga Chlamydomonas reinhardtii by combinatorial engineering to biosynthesise nine macrocyclic STP backbones found in agarwood. A bioprocess following green-chemistry principles was developed that exploits milking of STPs without cell lysis, solvent-solvent STP extraction, solvent-STP nanofiltration, and bulk STP oxy-functionalisation to obtain terpene mixtures like those of agarwood. This process occurs with total solvent recycling and enables continuous production. Our synthetic-biology approach offers a sustainable alternative to harvesting agarwood trees to obtain mixtures of complex, fragrant, oxygenated STPs.

synthetic biology↗

bioRxiv2023

A tale of caution: How endogenous viral elements affect virus discovery in transcriptomic data

Large-scale metagenomic and -transcriptomic studies have revolutionized our understanding of viral diversity and abundance. In contrast, endogenous viral elements (EVEs), remnants of viral sequences integrated into host genomes, have received limited attention in the context of virus discovery, especially in RNA-Seq data. EVEs resemble their original viruses, a challenge that makes distinguishing between active infections and integrated remnants difficult, affecting virus classification and biases downstream analyses. Here, we systematically assess the effects of EVEs on a prototypical virus discovery pipeline, evaluate their impact on data integrity and classification accuracy, and provide some recommendations for better practices. We examined EVEs and exogenous viral sequences linked to Orthomyxoviridae, a diverse family of negative-sense segmented RNA viruses, in 13 genomic and 538 transcriptomic datasets of Culicinae mosquitoes. Our analysis revealed a substantial number of viral sequences in transcriptomic datasets. However, a significant portion appeared not to be exogenous viruses but transcripts derived from EVEs. Distinguishing between transcribed EVEs or exogenous virus sequences was especially difficult in samples with low viral abundance. For example, three transcribed EVEs showed full-length segments, devoid of frameshift and nonsense mutations, exhibiting sufficient mean read depths that qualify them as exogenous virus hits. Mapping reads on a host genome containing EVEs before assembly somewhat alleviated the EVE burden, but it led to a drastic reduction of viral hits and reduced quality of assemblies, especially in regions of the viral genome relatively similar to EVEs. Our study highlights that our knowledge of the genetic diversity of viruses can be altered by the underestimated presence of EVEs in transcriptomic datasets, leading to false positives and altered or missing sequence information. Thus, recognizing and addressing the influence of EVEs in virus discovery pipelines will be key to enhancing our ability to capture the full spectrum of viral diversity.

microbiology↗

bioRxiv2023

Mitochondrial translocation of TFEB regulates complex I and inflammation

TFEB is a master regulator of autophagy, lysosome biogenesis and mitochondrial metabolism that works, and immunity, primarily through transcription controlled by cytosol-to-nuclear translocation. Emerging data indicate additional regulatory interactions at the surface of organelles such as lysosomes. Here we show that TFEB has a non-transcriptional role in mitochondria, regulating the electron transport chain complex I to down-modulate inflammation. Proteomic analysis revealed extensive TFEB co-precipitation with several mitochondrial proteins, whose interactions are disrupted upon infection with S. Typhimurium. Localization of TFEB in the mitochondrial matrix was confirmed by high resolution confocal microscopy and biochemistry with translocation dependent on a conserved N-terminal TOMM20-binding motif enhanced by mTOR inhibition. Within the mitochondria, TFEB and protease LONP1 antagonistically co-regulate complex I, reactive oxygen species and the inflammatory response. Consequently, during infection, lack of TFEB specifically in the mitochondria exacerbates the expression of pro-inflammatory cytokines, contributing to innate immune pathogenesis.

cell biology↗

bioRxiv2022

The ketone body acetoacetate activates human neutrophils through FFA2R

Neutrophils express many surface receptors that sense environmental changes. One such sensor is FFA2R (free fatty acid receptor 2), a receptor that detects gut microbiota-derived short chain fatty acids. As such, FFA2R has been regarded as a molecular link between metabolism and inflammation. Our recent studies on FFA2R, using its endogenous agonist propionate in combination with allosteric modulators, have identified several novel aspects of FFA2R regulation. A recent study has also identified the ketone body acetoacetate as an endogenous ligand for mouse FFA2R. Whether human FFA2R also recognizes acetoacetate and how this recognition modulates human neutrophil functions has not been earlier investigated. In this study, we found that acetoacetate can induce a decrease of cAMP and translocation of {beta}-arrestin in cells overexpressing FFAR2. In addition, we show that similar to propionate, FFA2R specific allosteric modulators enhance acetoacetate-induced transient rise in cytosolic calcium, production of reactive oxygen species and cell migration in human neutrophils. In summary, we demonstrate that human neutrophils recognize the ketone body acetoacetate through FFA2R. Thus, our data further highlight the key role of FFA2R in inflammation and metabolism.

cell biology↗

bioRxiv2022

MembraneFold: Visualising transmembrane protein structure and topology

BackgroundAlphaFolds accuracy, which is often comparable to that of experimentally determined structures, has revolutionized protein structure research. Being a statistical method, AlphaFold implicitly infers the cellular environment, e.g. the cell membrane, from the protein sequence. Membrane protein topology prediction methods predict the cellular environment for each protein residue but not the structure. Current structure and topology tools thus provide complementary information. ResultsWe introduce the web server MembraneFold. MembraneFold combines protein structure (from an uploaded PDB file/AlphaFold DB/OmegaFold) and topology (DeepTMHMM) prediction in one server. The output is shown both as a structure with topology superimposed and as a sequence annotation. MembraneFold uses structures predicted by OmegaFold if neither a PDB file is uploaded nor the structure is available in AlphaFold DB. ConclusionMembraneFold is a user-friendly web server that provides practitioners with fast and accurate information about membrane proteins. It is available at https://ku.biolib.com/MembraneFold/.

bioinformatics↗

bioRxiv2022

Spatial scale influences taxon conservation in the eukaryotic virome of a mosquito

Our knowledge on the diversity of eukaryotic viruses has recently undergone a massive expansion. This diversity could influence host physiology through yet unknown phenomena of potential interest to the fields of health and food production. However, the assembly processes in eukaryotic viromes of terrestrial animals remain elusive. This situation hinders hypothesis-driven tests of virome influence on host physiology. Here, we explore virome assembly at different spatial scales in the eukaryotic virome of the mosquito Culex pipiens. This mosquito is a vector of human pathogens worldwide. Several new aspects of virome assembly were unveiled through a sampling involving five countries in Africa and Europe and large sample sizes. A group of viruses was conserved in C. pipiens populations in all countries. This core group represented a relatively large and diverse fraction of the virome. However, core viruses were not shared by all host individuals in a given country, and their infection rates fluctuated between countries and years. Moreover, the distribution of co-infections in individual mosquitoes suggested random co-occurrence of certain core viruses. We also observed differences in the virome depending on geography, with viromes tending to cluster depending on the continent. Thus, our results unveil that taxon conservation in a eukaryotic virome changes with spatial scale. Thus, predictions on virome assembly seem possible at a large geographical scale in C. pipiens. IMPORTANCEThe study of the eukaryotic virome of mosquitoes is an emerging research field. Beyond its fundamental interest, this field could lead to the development of control tools against the transmission of mosquito-borne human pathogens. However, we yet know little on the assembly patterns in the eukaryotic viromes of mosquitoes, as well as of terrestrial animals in general. This situation hampers the design of hypothesis-driven studies on the influence of the virome on pathogen transmission. Here, we have analyzed virome assembly in the mosquito vector Culex pipiens within and between countries in Africa and Europe. Our results show that integrating contrasted spatial scales allows to identify deterministic patterns in virome assembly. Such patterns can guide future studies of virome influence on mosquito physiology.

ecology↗

bioRxiv2021

S. Typhimurium impairs glycolysis-mediated acidification of phagosomes to evade macrophage defense

Regulation of the cellular metabolism is now recognized as a crucial mechanism for the homeostasis of innate and adaptive immune cells upon diverse extracellular stimuli. Macrophages, for instance, increase glycolysis upon stimulation with pathogen-associated molecular patterns (PAMPs). Conceivably, pathogens also counteract these metabolic changes for their own survival in the host. However, despite this dynamic interplay in host-pathogen interactions, the role of immunometabolism in the context of intracellular bacterial infections is still unclear. Here, employing unbiased metabolomic and transcriptomic approaches, we investigated the role of metabolic adaptations of macrophages upon Salmonella enterica serovar Typhimurium (S. Typhimurium) infections. Importantly, our results suggested that S. Typhimurium abrogates glycolysis and its modulators such as insulin-signaling to impair macrophage defense. Mechanistically, glycolytic enzyme aldolase A is critical for v-ATPase assembly and the acidification of phagosomes upon S. Typhimurium infection, and impairment in the glycolytic machinery eventually leads to decreased bacterial clearance and antigen presentation in macrophages. Collectively, our results highlight a vital molecular link between metabolic adaptation and phagosome maturation in macrophages, which is targeted by S. Typhimurium to evade cell-autonomous defense.

microbiology↗

bioRxiv2020

eEF1A2 controls local translation and actin dynamics in structural synaptic plasticity

Synaptic plasticity involves structural modifications in dendritic spines. Increasing evidence suggests that structural plasticity is modulated by local protein synthesis and actin remodeling in a synapsis-specific manner. However, the precise molecular mechanisms connecting synaptic stimulation to these processes in dendritic spines are still unclear. In the present study, we demonstrate that the configuration of phosphorylation sites in eEF1A2, an essential translation elongation factor in neurons, is a key modulator of structural plasticity in dendritic spines. A mutant that cannot be phosphorylated stimulates translation but reduces actin dynamics and spine density. By contrast, the phosphomimetic variant loosens its association with F-actin and becomes inactive as a translation elongation factor. Metabotropic glutamate receptor signaling triggers a transient dissociation of eEF1A2 from its GEF protein in dendritic spines, in a phospho-dependent manner. We propose that eEF1A2 establishes a crosstalk mechanism that coordinates local translation and actin dynamics during spine remodeling.

neuroscience↗

bioRxiv2020

Evolution of colonial life history in styelids tunicates involves changes in complexity patterns

Biological complexity is defined as the number of modules that compose an organism or a biological system, the type of interactions between these modules, and new hierarchies that describe these interactions. These patterns in biological complexity are changing during the evolution of life-histories, such as the evolution of coloniality in animals. In relation to coloniality, it is possible to observe an increment in all the aspects defined in the concept of biological complexity. First, in colonial animals, there is an increment in the modules that compound the system (i.e. zooids) compared with a solitary organism in which the multicellular individual a unity. Consequently, this transformation of the multicellular individual, in a component of the modular architecture in colonies, involves an increase in the regulatory processes of colonial system. This is precisely the case of the colonial life history evolution from solitary ancestors in the Styelids tunicates. Therefore, the main question of this study is How is the regulation of the asexual developmental processes that occurred simultaneously in the modules of the colonies? This question was studied, by the research of colonial strategy in the styelid Symplegma. Using in vivo observations of the budding process, description and classification of the extra-corporeal blood vessels system and the blood cells, by cytohistological assays. The conclusion is that the regulation of the simultaneous developmental processes that occurred in Symplegma colonies is mediated by the system of extra-corporeal blood vessels, which maintain physically the cohesion of the individuals, the plasma, and migratory blood cells transport signals between the individuals of the colonies.

developmental biology↗