Biology subjects

Teixeira, L.

Publications and source records attributed to Teixeira, L..

13 recordsLinked to original sources

bioRxiv2025

SEPSIS-INDUCED LIPID DROPLET ACCUMULATION ENHANCES ANTIBACTERIAL INNATE IMMUNITY

Lipid droplets (LDs) are lipid-rich organelles recognized as central players in lipid homeostasis, signaling, and inflammation. While their functions in inflammation are well-documented, the role of LDs in antibacterial immunity and infection resistance remains less understood. In this study, we investigated triglyceride synthesis and LD accumulation in the context of antibacterial innate immunity during sepsis. Our results show that LD accumulation is part of immunometabolic reprogramming in E. coli-infected macrophages. Pharmacological inhibition or genetic knockdown of DGAT1, a key enzyme in triglyceride synthesis, reduced LD formation, bacterial clearance, and pro-inflammatory responses (nitric oxide, PGE2, CCL2, IL-6, IFN-{beta}). Notably, DGAT1 inhibition impaired the expression of several interferon-stimulated genes (ISGs), including viperin, iNOS, cathelicidin, and IGTP, in E. coli-infected macrophages. In a sepsis model, DGAT1 inhibition reduced sepsis-induced LD accumulation in peritoneal cells and decreased levels of CCL2, IFN-{beta}, nitric oxide, and lipid mediators (PGE2, LTB4, and RvD1). Furthermore, DGAT1 inhibition accelerated sepsis-related mortality, coinciding with elevated bacterial loads in the peritoneum and bloodstream at 6 and 24 hours post-sepsis. Our results demonstrate that tryglicerides synthesis and LDs are critical regulators of infection resistance, contributing to both bacterial clearance and the coordination of a protective proinflammatory response during sepsis.

immunology↗

bioRxiv2024

A flexible fluid delivery system for rodent behavior experiments

Experimental behavioral neuroscience relies on the ability to deliver precise amounts of liquid volumes to animal subjects. Among others, it allows the progressive shaping of behavior through successive, automated, reinforcement, thus allowing training in more demanding behavioral tasks and the manipulation of variables that underlie the decision making process (e.g.: reward magnitude). Here we introduce a stepper-motor-based, fully integrated, open-source solution, that allows the reproducible delivery of small (<1 {micro}L) liquid volumes. The system can be controlled via software using the Harp protocol (e.g.: from Bonsai or Python interfaces), or directly through a low-level I/O interface. Both the control software and electronics are compatible with a wide variety of motor models and mechanical designs. However, we also provide schematics, and step-by-step assembly instructions, for the mechanical design used and characterized in this manuscript. We provide benchmarks of the full integrated system using a computer-vision method capable of measuring across-trial delivery of small volumes, an important metric when having behavior experiments in mind. Finally, we provide experimental validation of our system by employing it in a psychophysics rodent task, and during electrophysiological recordings.

bioengineering↗

bioRxiv2023

Brood division in a marsh-dwelling bird and its relation with the increase in offspring survival, acceleration of renest, and reduced competition for food resources

Parental care involves strategies that increase the offsprings survival. In some birds, each adult only feeds one young (brood division). Six hypotheses explain the functions of brood division: 1) reduced predation; 2) selection of a young by the parents; 3) selection of an adult by the young; 4) reduction of offspring competition; 5) efficiency improvement in parent-offspring interactions; and 6) social specialization. We studied the reproductive behavior and nestling morphology of the species to evaluate the possible functions associated with the brood division in Formicivora acutirostris, a bird of tidal marshes of southern Brazil. Females lay two eggs, but nests with one nestling may occur. We monitored 899 nests, nestlings, and parental care of young until they reached independence. Brood division occurred when the fledglings left the nest and continued until their independence. We did not observe a difference in the frequency with which sex feed single fledglings clutches. The fledglings remain in separated areas (pro hypothesis #1). There is a sex bias in the division (pro hypothesis #2). Adults fed the siblings equally (contra hypothesis #3). There is no aggression between siblings (contra hypothesis #4). Each fledgling remained close to their adult and responds only to it (pro hypotheses #5 and #6). We propose that brood division in the species may 7) reduce drowning of fledglings, 8) spatially divide food consumption, and 9) allow concomitant reproduction. We emphasize flooding as a structuring force for F. acutirostris, which raises concerns about the effects of climate change on this species.

animal behavior and cognition↗

bioRxiv2023

Novel pathways converge with quorum sensing to regulate plant and insect host-specific factors in Erwinia carotovora

Erwinia carotovora Ecc15 is a vector-borne phytopathogen that relies on insects to be transmitted between plant hosts. To interact with its hosts, this bacterium depends on host-specific bacterial traits. Plant tissue maceration depends on production of plant cell wall degrading enzymes (PCWDE), while survival in the digestive tract of the insect requires the Erwinia virulence factor (evf). Evf expression is responsible for the cost of Ecc15 infection in Drosophila melanogaster and overexpression is lethal to the insect host. Therefore, its expression must be well controlled. Expression of evf and PCWDEs is co-regulated by quorum sensing via the transcriptional regulator Hor. Since virulence factors are often controlled by multiple signals, we asked which additional factors regulate evf expression. Using a genetic screen, we identified the sensor histidine kinase arcB and a new TetR-like regulator (named herein as lvtR, after Low Virulence Transcriptional Repressor), as novel regulators not only of evf, but also of pelA, which encodes a major PCWDE. We further demonstrate that arcB and lvtR mutants have reduced plant tissue maceration and reduced development delay and lethality in Drosophila melanogaster, compared to wild-type bacteria. Thus showing the importance of these regulators in the establishment of Erwinia-host-vector interactions. We also found that ArcB and LvtR regulation converges on Hor, independently of quorum sensing, to co-regulate expression of both plant and insect bacterial interaction factors during plant infection. Taken together, our results reveal a novel regulatory hub that enables Ecc15 to integrate quorum sensing responses and environmental cues to co-regulate traits required for infection of both the plant and the insect vector. Moreover, we show that ArcB regulation of bacteria-host interaction processes is conserved in other bacteria. Author SummaryVector-borne pathogens depend on continuous cycles of replication and transmission between hosts and vectors, requiring multiple factors to interact with each of the hosts. The expression of these multiple interaction factors can be very costly, so it is expected that regulation of virulence has been evolutionarily tuned to produce expressions patterns that minimize the cost of establishing the infection while maximizing transmission efficiency of the pathogen. Here, we investigate the tripartite interaction between Ecc15, a plant and an insect, and show that quorum sensing, a widely conserved sensory regulator arcB and a regulator of previously unknown function, lvtR, converge to simultaneously co-regulate the expression of bacterial factors required for these interactions. Gene expression regulation is channeled through the conserved regulator Hor, which serves as a molecular hub for the integration of these multiple signals. Our data suggest that integration of multiple signals to co-regulate plant and insect associated factors ensure fine-tune titration of gene expression and maximization of bacterial energetic resources.

microbiology↗

bioRxiv2021

Viral route of infection determines the effect of Drosophila melanogaster gut bacteria on host resistance and tolerance to disease.

The microbial community interacting with a host can modulate the outcome of pathogenic infections. For instance, Wolbachia, one of the most prevalent invertebrate endosymbionts, strongly increases resistance of Drosophila melanogaster and other insect hosts, to many RNA viruses. D. melanogaster is also in continuous association with gut bacteria, whose role in antiviral immunity is poorly characterized. Here we asked how gut-colonizing bacteria impact viral titres and host survival, and how these interact with route of infection or Wolbachia presence. We compared germ-free flies and flies associated with two gut bacteria species recently isolated from wild flies (Acetobacter thailandicus and Lactobacillus brevis). We found that Wolbachia-conferred protection to both DCV or FHV is not affected by the presence or absence of these gut bacteria. Flies carrying A. thailandicus have lower DCV loads than germ-free flies, upon systemic infection, but reduced survival, indicating that these bacteria increase resistance to virus and decrease disease tolerance. Association with L. brevis, alone or in combination with A. thailandicus, did not lead to changes in survival to systemic infection. In contrast to the effect on systemic infection, we did not observe an impact of these bacteria on survival or viral loads after oral infection. Overall, the impact of gut-associated bacteria in resistance and tolerance to viruses was mild, when compared with Wolbachia. These results indicate that the effect of gut-associated bacteria to different viral infections, and different routes of infection, is complex and understanding it requires a detailed characterization of several parameters of infection.

immunology↗

bioRxiv2020

Regulation of Wolbachia proliferation by the amplification and deletion of an addictive genomic island

Wolbachia is one of the most prevalent bacterial endosymbionts, infecting approximately 40% of terrestrial arthropod species. Wolbachia is often a reproductive parasite but can also provide fitness benefits to its host, as, for example, protection against viral pathogens. This protective effect is currently being applied to fight arboviruses transmission by releasing Wolbachia-transinfected mosquitoes. Titre regulation is a crucial aspect of Wolbachia biology. Higher titres can lead to stronger phenotypes and fidelity of transmission but can have a higher cost to the host. Since Wolbachia is maternally transmitted, its fitness depends on host fitness, and, therefore, its cost to the host may be under selection. Understanding how Wolbachia titres are regulated and other aspects of Wolbachia biology has been hampered by the lack of genetic tools. Here we developed a forward genetic screen to identify new Wolbachia over-proliferative mutant variants. We characterized in detail two new mutants, wMelPop2 and wMelOctoless, and show that the amplification or loss of the Octomom genomic region lead to over-proliferation. These results confirm previous data and expand on the complex role of this genomic region in the control of Wolbachia proliferation. Both new mutants shorten the host lifespan and increase antiviral protection. Moreover, we show that Wolbachia proliferation rate in Drosophila melanogaster depends on the interaction between Octomom copy number, the host developmental stage, and temperature. Our analysis also suggests that the life shortening and antiviral protection phenotypes of Wolbachia are dependent on different, but related, properties of the endosymbiont; the rate of proliferation and the titres near the time of infection, respectively. Altogether, we demonstrate the feasibility of a novel and unbiased experimental approach to study Wolbachia biology, which can be further adapted to characterize other genetically intractable bacterial endosymbionts.

microbiology↗

bioRxiv2020

Lipid droplets fuels SARS-CoV-2 replication and inflammatory response

Viruses are obligate intracellular parasites that make use of the host metabolic machineries to meet their biosynthetic needs, identifying the host pathways essential for the virus replication may lead to potential targets for therapeutic intervention. The mechanisms and pathways explored by SARS-CoV-2 to support its replication within host cells are not fully known. Lipid droplets (LD) are organelles with major functions in lipid metabolism and energy homeostasis, and have multiple roles in infections and inflammation. Here we described that monocytes from COVID-19 patients have an increased LD accumulation compared to SARS-CoV-2 negative donors. In vitro, SARS-CoV-2 infection modulates pathways of lipid synthesis and uptake, including CD36, SREBP-1, PPAR{gamma} and DGAT-1 in monocytes and triggered LD formation in different human cells. LDs were found in close apposition with SARS-CoV-2 proteins and double-stranded (ds)-RNA in infected cells. Pharmacological modulation of LD formation by inhibition of DGAT-1 with A922500 significantly inhibited SARS-CoV-2 replication as well as reduced production of pro-inflammatory mediators. Taken together, we demonstrate the essential role of lipid metabolic reprograming and LD formation in SARS-CoV-2 replication and pathogenesis, opening new opportunities for therapeutic strategies to COVID-19.

immunology↗

bioRxiv2020

The neuropeptides VIP and PACAP inhibit SARS-CoV-2 replication in monocytes and lung epithelial cells and decrease the production of proinflammatory cytokines in infected cells.

Infection by SARS-CoV-2 may elicit uncontrolled and damaging inflammatory responses. Thus, it is critical to identify compounds able to inhibit virus replication and thwart the inflammatory reaction. Here, we show that the plasma levels of the immunoregulatory neuropeptide VIP are elevated in patients with severe COVID-19, correlating with reduced inflammatory mediators and with survival on those patients. In vitro, VIP and PACAP, highly similar neuropeptides, decreased the SARS-CoV-2 genome replication in human monocytes and viral production in lung epithelial cells, also reducing cell death. Both neuropeptides inhibited the production of proinflammatory mediators in lung epithelial cells and in monocytes. VIP and PACAP prevented in monocytes the SARS-CoV-2-induced activation of NF-kB and SREBP1 and SREBP2, transcriptions factors involved in proinflammatory reactions and lipid metabolism, respectively. They also promoted CREB activation, a transcription factor with antiapoptotic activity and negative regulator of NF-kB. Specific inhibition of NF-kB and SREBP1/2 reproduced the anti-inflammatory, antiviral and cell death protection effects of VIP and PACAP. Our results support further clinical investigations of these neuropeptides against COVID-19.

microbiology↗

bioRxiv2020

Wolbachia-conferred antiviral protection is determined by developmental temperature

Wolbachia is a maternally transmitted bacterium widespread in arthropods and filarial nematodes, and confers strong antiviral protection in Drosophila melanogaster and other insects. Wolbachia-transinfected Aedes aegypti are currently being deployed to fight transmission of dengue and Zika viruses. However, the mechanism of antiviral protection and factors influencing it are still not fully understood. Here we show that temperature modulates Wolbachia-conferred protection in Drosophila melanogaster. Temperature after infection directly impacts Drosophila C virus replication and modulates Wolbachia protection. At higher temperatures virus proliferates more and is more lethal, while Wolbachia confers lower protection. Strikingly, host developmental temperature is a determinant of Wolbachia-conferred antiviral protection. While there is a strong protection when flies are raised from egg to adult at 25{degrees}C, the protection is highly reduced or completely abolished when flies develop at 18{degrees}C. However, Wolbachia-induced changes during development are not sufficient to limit virus-induced mortality, as Wolbachia is still required to be present in adults at the time of infection. This developmental effect is general, since it was present in different host genotypes, Wolbachia variants and upon infection with different viruses. Overall, we show that Wolbachia-conferred antiviral protection is temperature dependent, being present or absent depending on the environmental conditions. This interaction likely impacts Wolbachia-host interactions in nature and, as a result, frequencies of host and symbionts in different climates. Dependence of Wolbachia-mediated pathogen blocking on developmental temperature could be used to dissect the mechanistic bases of protection and should be considered by programmes deploying Wolbachia as an antiviral agent in the field. Significance StatementInsects are often infected with beneficial intracellular bacteria. The bacterium Wolbachia can protect insects from pathogenic viruses. This effect can be used to prevent transmission of dengue and Zika viruses by Wolbachia-infected mosquitoes. To deploy Wolbachia in the field successfully and understand the biology of insects in the wild we need to discover which factors affect Wolbachia-conferred antiviral protection. Here we show that the temperature in which insects develop from eggs to adults can determine presence or absence of antiviral protection. The environment, therefore, influences this insect-bacterium interaction. Our work may help to provide insights into the mechanism of viral blocking by Wolbachia and inform programs using Wolbachia in mosquito-borne disease control.

microbiology↗

bioRxiv2019

Quorum sensing regulation in Erwinia carotovora affects development of Drosophila melanogaster infected larvae

Multi-host bacteria must rapidly adapt to drastic environmental changes, relying on integration of multiple stimuli for an optimal genetic response. Erwinia spp. are phytopathogens that cause soft-rot disease in plants. Erwinia carotovora Ecc15 is used as a model for bacterial oral-route infection in Drosophila melanogaster as it harbors a gene, the Erwinia virulence factor (Evf), which has been previously shown to be a major determinant for infection of D. melanogaster gut. However, the factors involved in regulation of evf expression are poorly understood. We investigated whether evf could be controlled by quorum sensing since, in the Erwinia genus, quorum sensing regulates pectolytic enzymes, the major virulence factors needed to infect plants. Here, we show that transcription of evf is positively regulated by quorum sensing in Ecc15 via the acyl-homoserine lactone (AHL) signal synthase ExpI, and the AHL receptors ExpR1 and ExpR2. Moreover, we demonstrate that the GacS/A two-component system is partially required for evf expression. We also show that the load of Ecc15 in the gut depends upon the quorum sensing-mediated regulation of evf. Furthermore, we demonstrate that larvae infected with Ecc15 suffer a developmental delay as a direct consequence of the regulation of evf via quorum sensing. Overall, our results show that Ecc15 relies on quorum sensing to control production of both pectolytic enzymes and Evf. This regulation influences the interaction of Ecc15 with its two known hosts, indicating that quorum sensing and GacS/A signaling systems may impact bacterial dissemination via insect vectors that feed on rotting plants. SignificanceIntegration of genetic networks allows bacteria to rapidly adapt to changing environments. This is particularly important in bacteria that interact with multiple hosts. Erwinia carotovora Ecc15 is a plant pathogen that uses Drosophila melanogaster as a vector. To interact with these two hosts, Ecc15 uses two different sets of virulence factors: plant cell wall-degrading enzymes to infect plants and the Erwinia virulence factor (evf) to infect Drosophila. Our work shows that, despite the virulence factors being different, both are regulated by homoserine lactone quorum sensing and the two component GacS/A system. Moreover, we show that these pathways are essential for Ecc15 loads in the gut of Drosophila and that this interaction carries a cost to the vector in the form of a developmental delay. Our findings provide evidence for the importance of quorum sensing regulation in the establishment of multi-host interactions.

microbiology↗

bioRxiv2018

Effect of partial substitution of rice with sorghum and inclusion of hydrolyzable tannins on digestibility and postprandial glycemia in adult dogs

Sorghum is used as a substitute of rice in dog food, owing to its nutritional similarity and low cost. However, its use has been associated with negative effects, like a reduction in palatability, digestibility, and enzyme activity, which can decrease nutrient absorption. The presence of condensed tannins (CT) in sorghum may cause these effects. Another tannin group, the hydrolysable tannins (HT), is known for its antioxidant properties. Research has shown the nutritional effects of sorghum on dogs, but the effect of HT on dogs remains unknown. We evaluated the effects of substituting rice with sorghum containing CT and inclusion of commercial extract of HT on digestibility, fecal and urinary characteristics, and postprandial blood glucose levels in adult dogs. Nine adult Beagle were randomly subjected to 4 treatments: 50% rice; (RS) 25% rice + 25% sorghum; (RHT) 50% rice + 0.10% HT; (RSHT) 25% rice + 25% sorghum + 0,10% HT. Tannins did not affect food intake. The digestibility of dry matter, organic matter, crude protein, acid hydrolyzed fat, gross energy, and metabolizable energy (ME) decreased with sorghum inclusion (P < 0.05). Sorghum also decreased protein digestibility (P < 0.05). Greater fecal dry matter was observed with the RHT diet. HT associated with sorghum reduced ME (P < 0.05). Sorghum inclusion enhanced fecal output, without altering fecal score (P > 0.05). No alterations in urinary characteristics were observed. Sorghum and HT did not affect the postprandial blood glucose response measured by the area under the curve (P > 0.05). The substitution of rice by sorghum negatively affected protein absorption and ME of the diets. Sorghum can be considered as a good source of carbohydrates in therapeutic diets for weight control. HT may potentiate the effect of CT, but more research is needed to evaluate its potential use in dog nutrition.

biochemistry↗

bioRxiv2018

Drosophila melanogaster establishes a species-specific mutualistic interaction with stable gut-colonizing bacteria

Animals live together with diverse bacteria that can impact their biology. In Drosophila melanogaster, gut-associated bacterial communities are relatively simple in composition but also have a strong impact on host development and physiology. However, it is still unknown if bacteria can proliferate and stably associate with the gut of D. melanogaster. In fact, it is generally assumed that bacteria are transient and their constant ingestion with food is required to maintain their presence in the gut. Here, we identify bacterial species from wild-caught D. melanogaster that stably associate with the host independently of continuous inoculation. Moreover, we show that specific Acetobacter wild isolates can proliferate in the gut. We further demonstrate that the interaction between D. melanogaster and the wild isolated Acetobacter thailandicus is mutually beneficial and that the stability of the gut association is key to this mutualism. The stable population in the gut of D. melanogaster allows continuous bacterial spreading into the environment, which is advantageous to the bacterium itself. The bacterial dissemination is in turn advantageous to the host since the next generation of flies develops in the presence of this particularly beneficial bacterium. Ac. thailandicus leads to a faster host development and higher fertility of emerging adults, when compared to other bacteria isolated from wild-caught flies. Furthermore, Ac. thailandicus is sufficient and advantageous when D. melanogaster develops in axenic or freshly collected figs, respectively. This isolate of Ac. thailandicus colonizes several genotypes of D. melanogaster but not of the closely related Drosophila simulans, indicating that the stable association is host specific. This work establishes a new conceptual model to understand D. melanogaster- gut microbiota interactions in an ecological context; stable interactions can be mutualistic through microbial farming, a common strategy in insects. Moreover, these results develop the use of D. melanogaster as a model to study gut microbiota proliferation and colonization.\n\nAuthor summaryAnimals, including humans, live together with complex bacterial communities in their gut that influence their physiology and health. The fruit fly Drosophila melanogaster has been an excellent model organism to study host-microbe interactions and harbours a relative simple gut bacterial community. However, it is not known which of these bacteria can proliferate and form stable communities in the gut, and the current hypothesis is that these bacteria are only transiently associated with the gut. Here, we show that in D. melanogaster collected from a natural population stable gut bacteria do exist. We isolated specific species that can proliferate in the gut and form a stable association. This is beneficial to the bacteria since they can be constantly spread by the flies as they move around. On the other hand, this is a form of farming as the next generation of flies benefit from the association with these particular bacteria during development. They become adults faster and are more fertile than if they develop with other bacteria encountered in nature. These advantages are also observed when flies develop in figs, a natural food source. Our findings show that D. melanogaster has stable colonizing bacteria in the gut and establish a new framework to study host-gut bacteria interactions.

microbiology↗

bioRxiv2017

Within host selection for faster replicating bacterial symbionts

Wolbachia is a widespread, intracellular symbiont of arthropods, able to induce reproductive distortions and antiviral protection in insects. Wolbachia can also be pathogenic, as is the case with wMelPop, a virulent variant of the endosymbiont of Drosophila melanogaster. An extensive genomic amplification of the 20kb region encompassing eight Wolbachia genes, called Octomom, is responsible for wMelPop virulence. The Octomom copy number in wMelPop can be highly variable between individual D. melanogaster flies, even when comparing siblings arising from a single female. Moreover, Octomom copy number can change rapidly between generations. These data suggest an intra-host variability in Octomom copy number between Wolbachia cells. Since wMelPop Wolbachia with different Octomom copy numbers grow at different rates, we hypothesized that selection could act on this intra-host variability. Here we tested if total Octomom copy number changes during the lifespan of individual Drosophila hosts, revealing selection for different Wolbachia populations. We performed a time course analysis of Octomom amplification in flies whose mothers were controlled for Octomom copy number. We show that despite the Octomom copy number being relatively stable it increases slightly throughout D. melanogaster adult life. This indicates that there is selection acting on the intra-host variation in the Octomom copy number over the lifespan of individual hosts. This within host selection for faster replicating bacterial symbionts may be in conflict with between host selection against highly pathogenic Wolbachia.

microbiology↗