Biology subjects

Teixeira, C.

Publications and source records attributed to Teixeira, C..

10 recordsLinked to original sources

bioRxiv2026

Maxillary constriction causes nasal septum deviation and deformity of the nasal floor

IntroductionWe investigated the direct effect of transverse maxillary constriction on nasal septal deviation (NSD) and nasal floor slanting. Methods and Materials60 growing Wistar rats (21days old) were divided into four groups (n=15): 1) Experimental Group 1 received active constriction force (100cN), 2) Experimental Group 2 received active expansion force (100cN), 3) Sham received the same spring as Experimental Groups without receiving any active force, and 4) Control group did not receive any appliance. Samples were collected after 28 days for microcomputed tomography (CT) analysis. ResultsExperimental Group 1 demonstrated maxillary constriction (both skeletal and dental), accompanied by mandibular shift on closure, clockwise mandibular rotation, and increased mandibular plane angle and facial height. Constriction also produced severe nasal floor slanting in the molar area that extended posteriorly. Nasal floor canting was accompanied by a slanted vomer and a C-shaped NSD. The direction of nasal floor canting and mandibular shift was always similar. Experimental Group 2, on the other hand, was not associated with nasal deviation, and a slight slanting of the nasal floor was observed only when there was a mandibular shift. ConclusionOur study suggests that the constricting transverse forces applied to the maxilla can induce slanting of the nasal floor and, consequently, the vomer, which in turn can lead to nasal septal deviation. Slanting of the nasal floor is caused mainly by rotation of the hemimaxilla in response to transverse forces and changes in occlusal forces due to a mandibular shift.

developmental biology↗

bioRxiv2025

Lutzomyia longipalpis salivary proteins elicit human innate and adaptive immune responses detrimental to Leishmania parasites

In Leishmania-endemic areas, humans are constantly exposed to sand fly bites. To explore the immune consequences of this chronic vector exposure, we performed a human challenge study with the sand fly Lutzomyia longipalpis. Peripheral blood mononuclear cells were collected from fifteen healthy volunteers who underwent multiple controlled exposures to sand fly bites. We identified two Lu. longipalpis salivary proteins, LJM19 and LJL143, which elicited type 1 cytokine responses in cells from exposed individuals and which correlated with enhanced killing of Leishmania parasites in co-cultured macrophages. Interestingly, LJM19 also exerted this parasite-killing effect in cells from unexposed individuals, consistent with innate immune activation. In support of this, both LJM19 and LJL143 stimulated the production of the innate cytokines IL-1{beta} and IFN-. Our results demonstrate that repeated exposure to sand fly bites induces innate and adaptive cytokine responses to vector salivary proteins that can be co-opted to protect humans against Leishmania infection.

immunology↗

bioRxiv2024

Inclusion of Salicornia ramosissima biomass in diets for juvenile whiteleg shrimp (Penaeus vannamei) induces favourable but transient effects in the immune and oxidative status

The whiteleg shrimp, Penaeus vannamei, is a highly valued and globally produced crustacean species. However, the rising cost of shrimp feed, exacerbated by increasing cereal prices, prompts the exploration of cost-effective and sustainable formulations for shrimp farming. This study investigates the potential of Salicornia ramosissima, a non-edible biomass co-product, as a substitute for wheat meal in juvenile whiteleg shrimp diets, aiming to create economically and ecologically sound formulations. The present study aimed to assess the impact of incorporating S. ramosissima into whiteleg shrimp aquafeeds on various aspects of shrimp development, including growth performance, survival, immune status, and oxidative status. A commercial-like diet was formulated and served as control, whereas four other diets contained S. ramosissima stems or a combination of leaves and seeds, both at inclusion levels of 5% and 10%, in addition to the control diet. Whiteleg shrimps were fed the experimental diets for 31 and 55 days, followed by a bacterial bath challenge to gauge their immune response to pathogens. At the end of the feeding period, whiteleg shrimps growth performance and survival rates remained consistent across all diets. However, whiteleg shrimp fed diets with S. ramosissima inclusion consumed more feed to achieve similar weights to those fed on the control diet, particularly in diets containing leaves and seeds at a 10% inclusion level, likely due to lower digestibility of dry matter, lipids, and energy. While S. ramosissima biomass inclusion did not affect shrimp weight, relative growth rate, or survival, it did lead to higher feed conversion ratios and feed intake, suggesting differences in nutrient digestibility and metabolic utilization. Additionally, S. ramosissima inclusion affected whiteleg shrimps overall body composition, particularly moisture and ash content. Dietary S. ramosissima inclusion modulated antioxidant enzyme activity in the shrimps hepatopancreas, indicating potential health improvements. The study also observed gene expression changes related to antioxidant enzymes, indicating an overall down-regulation with the inclusion of S. ramosissima. Despite challenges in feeding efficiency, the inclusion of S. ramosissima, especially stems, shows promise in reducing feed costs by utilizing a by-product. Furthermore, S. ramosissima inclusion led to subtle changes in certain plasma humoral parameters and hepatopancreas gene expression. Although some immune parameters varied, these effects appeared to diminish over time. In conclusion, this study highlights the potential of S. ramosissima as a functional feed ingredient capable of enhancing shrimps antioxidant response, aligning with global resource optimization and sustainability initiatives.

immunology↗

bioRxiv2023

Butyrate-producing bacteria as probiotic supplement: beneficial effects on metabolism and modulation of behavior in an obesity mouse model

Obesity is a risk factor for cardio-metabolic and neurological disease. The contribution of gut microbiota to derangements of the gut-brain axis in the context of obesity has been acknowledged, particularly through physiology modulation by short-chain fatty acids (SCFAs). Thus, probiotic interventions and administration of SCFAs have been employed with the purpose of alleviating symptoms in both metabolic and neurological disease. We have tested the effects of four butyrate-producing bacteria from the Lachnospiraceae family on the development of metabolic syndrome and behavioural alterations in a mouse model of diet-induced obesity. Male mice were fed either a high-fat diet (HFD) or an ingredient-matched control diet for 2 months, and bacteria cultures or culture medium were given by gavage to HFD-fed mice every second day. Assessment of the mice through a battery of metabolic and behaviour tests revealed that one of the administered bacteria affords some degree of protection against the development of obesity and its complications.

physiology↗

bioRxiv2023

RlmQ: A Newly Discovered rRNA Modification Enzyme Bridging RNA Modification and Virulence Traits in Staphylococcus aureus

rRNA modifications play crucial roles in fine-tuning the delicate balance between translation speed and accuracy, yet the underlying mechanisms remain elusive. Comparative analysis of the ribosomal RNA modifications in taxonomically distant bacteria could help define their general as well as species-specific roles. In this study, we identified a new methyltransferase, RlmQ, in Staphylococcus aureus responsible for the Gram-positive specific m7G2601, which is not modified in E. coli (G2574). We also demonstrate the absence of methylation on C1989, equivalent to E. coli C1962, which is methylated at position 5 by the Gram-negative specific RlmI methyltransferase, a paralogue of RlmQ. Both modifications (S. aureus m7G2601 and E. coli m5C1962) are situated within the same tRNA accommodation corridor, hinting at a potential shared function in translation. Inactivation of S. aureus rlmQ causes the loss of methylation at G2601 and significantly impacts growth, cytotoxicity, and biofilm formation. These findings unravel the intricate connections between rRNA modifications, translation, and virulence in pathogenic Gram-positive bacteria.

molecular biology↗

bioRxiv2023

Distinct disease-modifying therapies are associated with different blood immune cell profiles in people with relapsing-remitting multiple sclerosis

Disease modifying therapies (DMTs) used for treating people with relapsing-remitting multiple sclerosis (pwRRMS) target the immune system by different mechanisms of action. However, there is a lack of a comprehensive comparison of their effects on the immune system. Herein, we evaluated the numbers of circulating B cells, CD4+ and CD8+ T cells, regulatory T cells (Tregs), natural killer (NK) cells and NKT cells, and their subsets, in pwRRMS who were treatment-naive or treated with different DMTs. Compared to treatment-naive pwRRMS, common and divergent effects on immune system cells were observed on pwRRMS treated with different DMTs, with no consistent pattern across all therapies in any of the cell populations analysed. PwRRMS treated with fingolimod, dimethyl fumarate (DMF), or alemtuzumab have reduced numbers of CD4+ and CD8+ T cells, as well as Treg subsets, with fingolimod causing the most pronounced decrease in T cell subsets. In contrast, teriflunomide and interferon (IFN) {beta} have minimal impact on T cells, and natalizumab marginally increases the number of memory T cells in the blood. The effect of DMTs on the B cell, NKT and NK cell subsets is highly variable with alemtuzumab inducing a strong increase in the number of the most immature NK cells and its subsets. This study highlights the absence of a consistent pattern of the impact of various DMTs on immune system cells, with variations in both direction and magnitude of effect thus reenforcing the notion that distinct immune cell subsets are potential players in MS pathophysiology and/or DMT efficacy.

immunology↗

bioRxiv2023

Yeast extract improves growth in rainbow trout (Oncorhynchus mykiss) fed a fishmeal-free diet and modulates the hepatic and distal intestine transcriptomic profile

Replacing fishmeal with alternative protein sources and improving new ingredients diets with feed additives are major objectives in aquaculture. The aim of this study was to evaluate benefits for rainbow trout (Oncorhynchus mykiss) of supplementing a fishmeal-free diet, composed of processed animal proteins, with yeast extract. Juvenile rainbow trout (initial weight 37 {+/-} 2 g) were fed either with a control diet (19% fishmeal) or with a diet based on terrestrial animal by-products (17%) supplemented or not with 3% of yeast extract. Effects of the diets were evaluated in a 4-week digestibility trial and a 12-week growth experiment. Fish health was investigated by measuring plasma immune markers and performing histological study of the gut. Underlying molecular responses were investigated using unbiased transcriptomic analysis of the liver and distal intestine. Results indicated that supplementing with 3% yeast extract did not influence nutrient digestibility substantially. Nevertheless, fish fed the supplemented fishmeal-free diet grew more than those fed the non-supplemented processed animal protein diet. Plasma and structural parameters indicated no exacerbated immune response or signs of intestinal inflammation in fish fed the fishmeal-free diets. However, plasma total immunoglobulin M levels and intestinal villi were significantly higher in fish fed the diet supplemented with yeast extract. The transcriptomic analysis revealed that the diets influenced immune, inflammatory, pathogen fighting and coagulation gene-related expressions. These results suggest that the dietary inclusion of yeast can enhance a fishmeal-free diet by improving rainbow trout performances and potentially their robustness.

physiology↗

bioRxiv2022

Complex regulation of gamma-hemolysin expression impacts S. aureus virulence

Staphylococcus aureus gamma-hemolysin CB (HlgCB) is a core-genome encoded pore-forming toxin that targets the C5a receptor, similarly as the phage-encoded Panton-Valentine Leucocidin. Absolute quantification by mass spectrometry of HlgCB in 39 community-acquired pneumonia (CAP) isolates showed considerable variations in HlgC and HlgB yields between isolates. Interestingly, when testing the hypothesis that HlgCB might be associated with severe S. aureus CAP, we found that a high level of HlgCB synthesis was associated with mortality in a rabbit model of pneumonia. To decipher the molecular basis for the variation in hlgCB and hlgB expression and protein production among strains, different regulation levels were analyzed in representative clinical isolates and reference strains. Although HlgC and HlgB are encoded on a single operon, their levels were dissociated in 10% of the clinical strains studied. HlgCB amount and HlgC/HlgB ratio were found to both depend on promotor activity, mRNA stability and translatability, and on the presence of an individual hlgB mRNA processed from the hlgCB transcript. Strikingly, toe-printing and in vitro translation assays revealed that a single SNP in the 5-UTR of hlgCB mRNA strongly impaired hlgC translation in the USA300 strain, leading to a strong decrease in HlgC but not in HlgB; the level of HlgB is likely to have been maintained by the presence of the processed hlgB mRNA. This work illustrates the complexity of virulence factor expression in clinical strains and demonstrates a butterfly effect, where subtle genomic variations have a major impact on phenotype and virulence. Author SummaryThe Gram-positive bacterium Staphylococcus aureus can provoke a wide range of infections due to its ability to produce a large diversity of virulence factors, including immune evasion molecules, adhesins, and toxins. Some of these toxin-encoding genes are localized in mobile genetic elements, and are thus not present in all strains, whilst others are encoded in the core-genome and present in all strains. Gamma-hemolysin CB is a core-genome encoded toxin but its amount varies between community-acquired pneumonia isolates. The regulation mechanisms underlying this variation however, are not well characterized. Here, we show that gamma-hemolysin expression levels vary largely among clinical strains and that, when highly produced, it induces high mortality in a rabbit model of pneumonia. The molecular basis for the variation in gamma-hemolysin expression depends on multiple mechanisms including promoter strength, transcript stability and processing, and translatability (i.e. the amount of protein that is synthetized by the ribosome for a given transcript). Incredibly, all these factors rely on a subtle genetic modification. This work emphasizes the importance of the disparity in virulence factor expression among clinical isolates and points the extreme complexity of the molecular mechanisms underlying their regulation, rendering the prediction of virulence for a clinical isolate difficult.

microbiology↗

bioRxiv2020

Novel xylan degrading enzymes from polysaccharide utilizing loci of Prevotella copri DSM18205

Prevotella copri DSM18205 is a bacterium, classified under Bacteroidetes that can be found in the human gastrointestinal tract (GIT). The role of P. copri in the GIT is unclear, and elevated numbers of the microbe have been reported both in dietary fiber-induced improvement in glucose metabolism but also in conjunction with certain inflammatory conditions. These findings raised our interest in investigating the possibility of P. copri to grow on xylan, and identify the enzyme systems playing a role in digestion of xylan-based dietary fibers in P. copri, which currently are unexplored. Two xylan degrading polysaccharide utilizing loci (PUL10 and 15) were found in the genome, with three and eight GH-encoding genes, respectively. Three of the eight gene products were successfully produced in Escherichia coli: One monomeric two-domain extracellular enzyme from GH43 (subfamily 12, in PUL10, 60 kDa) and two dimeric single module enzymes from PUL15, one extracellular GH10 (41 kDa), and one intracellular GH43 subfamily 1 enzyme (37 kDa). The GH43_12 enzyme was hydrolysing arabinofuranose residues from different substrates, and a model of the 3D-structure revealed a single arabinose binding pocket. The GH10 (1) and GH43_1 are cleaving the xylan backbone. Hydrolysis products of GH10 (1) were DP2-4, and seven subsites (-3 to +4) were predicted in the 3D-model of the GH10 active site. GH43_1 mainly produced xylose (in line with its intracellular location). Based on our results we propose that in PUL15, GH10 (1) is an extracellular endo-1,4-{beta}-xylanase, that hydrolyses mainly glucuronosylated xylan polymers to xylooligosaccharides (XOS); while, GH43_1 in the same PUL, is an intracellular {beta}-xylosidase, catalysing complete hydrolysis of the XOS to xylose. In PUL10, the characterized GH43_12 is an arabinofuranosidase, with a role in degradation of arabinoxylan, catalysing removal of arabinose-residues on xylan polymers.

biochemistry↗

bioRxiv2018

State-dependent changes in olfactory cortical networks via cholinergic modulation

Activity in sensory cortical networks reflects both peripheral sensory input and intra- and inter-cortical network input. How sensory cortices balance these diverse inputs to provide relatively stable, accurate representations of the external world is not well understood. Furthermore, neuromodulation could alter the balance of these inputs in a state- and behavior-dependent manner. Here, we used optogenetic stimulation to directly assay the relative strength of bottom-up (olfactory bulb) and top-down (lateral entorhinal cortex) synaptic inputs to piriform cortex in freely moving rats. Optotrodes in the piriform cortex were used to test the relative strength of these two inputs, in separate animals, with extracellular, monosynaptic evoked potentials. The results suggest a rapid state-dependent shift in the balance of bottom-up and top-down inputs to PCX, with enhancement in the strength of lateral entorhinal cortex synaptic input and stability or depression of olfactory bulb synaptic input during slow-wave sleep compared to waking. The shift is in part due to a state-dependent change in cholinergic tone as assessed with fiber photometry of GCaMP6 fluorescence in basal forebrain ChAT+ neurons, and blockade of the state-dependent synaptic shift with cholinergic muscarinic receptor activation.

neuroscience↗