Motility Response Research Articles

Functional Characterization of Transcriptional Regulator Rem in Candidatus Liberibacter asiaticus.

Citrus HLB, caused by Candidatus Liberibacter asiaticus (CLas), is the most devastating citrus disease worldwide. Usually 10% of total genes in bacteria are regulatory genes, but only 2% of CLas genes encode transcriptional factors. Here, 20 transcriptional regulators were predicted including eight genes (lsrB, ldtR, rem, visR, visN, ctrA, mucR, pelD, and atoC) directly or indirectly involved in regulating motility, and five genes (i.e., rpoH, prbP, phrR, rirA, and lsrB) involved in oxidative stress response. We demonstrated that rem, lsrB, and visNR of CLas can complement the corresponding mutants of S. meliloti in their reduced motility. We further investigated traits controlled by Rem in S. meliloti and CLas using RNA-seq analyses of rem mutant vs. complementation strains with remSmc or remLas. Transcriptomic analysis showed RemLas significantly regulates the expression of genes in S. meliloti, which was used to infer its regulation of CLas genes by identification of homologous genes. We found Rem is involved in regulating motility, chemotaxis, transporters, and oxidative phosphorylation in S. meliloti and regulating flagellar and transporter genes in CLas. Among the 39 putative RemLas-regulated genes in CLas, 16 contain Rem binding motif, including 10 genes involved in flagellar assembly. Taken together, this study offers valuable insights regarding regulatory genes of CLas with many of them involved in regulating motility and oxidative stress response. The regulation of flagellar genes by Rem in CLas unravels critical information regarding motility in CLas infection of hosts.

Correlation of fecal microbiome dysregulation to synovial transcriptome in an equine model of obesity associated osteoarthritis.

Osteoarthritis (OA) is increasingly thought to be a multifactorial disease in which sustained gut inflammation serves as a continued source of inflammatory mediators driving degenerative processes at distant sites such as joints. The objective of this study was to use the equine model of naturally occurring obesity associated OA to compare the fecal microbiome in OA and health and correlate those findings to differential gene expression synovial fluid (SF) cells, circulating leukocytes and cytokine levels (plasma, SF) towards improved understanding of the interplay between microbiome and immune transcriptome in OA pathophysiology. Feces, peripheral blood mononuclear cells (PBMCs), and SF cells were isolated from healthy skeletally mature horses (n=12; 6 males, 6 females) and those with OA (n=6, 2 females, 4 males). Horses were determined to have OA via lameness evaluation, response to intra-articular (IA) diagnostic analgesia, and radiographic and arthroscopic evidence. Horses were excluded who had received medications or joint injections within 2 months. Cytokine analyses of plasma and SF were performed via multiplex immunoassay. Fecal bacterial microbial 16s DNA sequencing was performed and correlated to bulk RNA sequencing of SF cells and PBMC performed using an Illumina based platform. Horses with OA had higher body condition scores (P=0.009). Cytokines were elevated in plasma [interleukin (IL)-2, IL-6, IL-18, interferon gamma (IFN-γ), interferon gamma inducible protein 10 (CXCL10 or IP-10), granulocyte colony-stimulating factor (G-CSF)] and SF (IL-1β, IL-6, IL-17A, IL-18, IP-10, G-CSF) in OA. Microbial principal coordinate analysis (PCoA) using Bray-Curtis dissimilarity for β-diversity demonstrated distinct grouping of samples from OA versus healthy horses (P=0.003). Faith alpha diversity was reduced in OA (P=0.02). Analysis of microbiome composition showed differential relative abundance of taxa on multiple levels in OA. Specific phyla (Firmicutes, Verrucomicrobia, Tenericutes, Fibrobacteres), correlated to transcriptomic differences related to cell structure, extracellular matrix, collagen, laminin, migration, and motility, or immune response to inflammation in OA. These findings provide compelling evidence for a link between obesity, gut microbiome dysbiosis and differential gene expression in distant joint sites associated with development of OA in a relevant large animal model, establishing a connection here that provides a platform from which development of therapeutic interventions targeting the gut microbiome can build.

Agreeability and gastrointestinal motility responses to fully characterized experimental pasta enriched in wheat by-products

Pasta, a Mediterranean diet staple, enhances well-being when enriched with healthy ingredients like durum wheat-germ (WG) and wheat-bran (WB). We studied the nutritional and clinical responses to four experimental pastas (EP1-EP4) made with de-oiled WG, WB, and microencapsulated durum wheat-oil (mWO), compared to a control pasta of water and semolina dough. WG addition significantly boosted total phenols and radical scavenging activity. Simulated colonic fermentation showed WG-enriched pasta enhanced short-chain fatty acids production.The clinical response to pasta was studied in 70 healthy subjects by semiquantitative scales of sensory perception, functional ultrasonography of gastric and gallbladder kinetics, and breath test for orocecal transit time. Sensory analysis revealed differences in odor, aftertaste, and overall pleasantness, especially in EP2. Gastrointestinal motility was similar across pastas, but EP3 had a shorter transit time and higher colonic fermentation. This study suggests that wheat by-products enriched pastas offer nutraceutical benefits, agreeability, digestibility, and sustainability.

Mitochondria are absent from microglial processes performing surveillance, chemotaxis, and phagocytic engulfment.

Microglia continually surveil the brain allowing for rapid detection of tissue damage or infection. Microglial metabolism is linked to tissue homeostasis, yet how mitochondria are subcellularly partitioned in microglia and dynamically reorganize during surveillance, injury responses, and phagocytic engulfment in the intact brain are not known. Here, we performed intravital imaging of microglia mitochondria, revealing that microglial processes diverge, with some containing multiple mitochondria while others are completely void. Microglial processes that engage in minute-to-minute surveillance typically do not have mitochondria. Moreover, unlike process surveillance, mitochondrial motility does not change with animal anesthesia. Likewise, the processes that acutely chemoattract to a lesion site or initially engage with a neuron undergoing programmed cell death do not contain mitochondria. Rather, microglia mitochondria have a delayed arrival into the responding cell processes. Thus, there is subcellular heterogeneity of mitochondrial partitioning and asymmetry between mitochondrial localization and cell process motility or acute damage responses.

Differential abundance of microRNAs in seminal plasma extracellular vesicles (EVs) in Sahiwal cattle bull related to male fertility.

Sahiwal cattle, known for their high milk yield, are propagated through artificial insemination (AI) using male germplasm, largely contingent on semen quality. Spermatozoa, produced in the testes, carry genetic information and molecular signals essential for successful fertilization. Seminal plasma, in addition to sperm, contains nano-sized lipid-bound extracellular vesicles (SP-EVs) that carry key biomolecules, including fertility-related miRNAs, which are essential for bull fertility. The current study focused on miRNA profiling of SP-EVs from high-fertile (HF) and low-fertile (LF) Sahiwal bulls. SP-EVs were isolated using size exclusion chromatography (SEC) and characterized by dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). Western blotting detected the EV-specific protein markers TSG101 and CD63. The DLS analysis showed SP-EV sizes of 170-180nm in HF and 130-140nm in LF samples. The NTA revealed particle concentrations of 5.76 × 1010 to 5.86 × 1011 particles/mL in HF and 5.31 × 1010 to 2.70 × 1011 particles/mL in LF groups, with no significant differences in size and concentration between HF and LF. High-throughput miRNA sequencing identified 310 miRNAs in SP-EVs from both groups, with 61 upregulated and 119 downregulated in HF bull. Further analysis identified 41 miRNAs with significant fold changes and p-values, including bta-miR-1246, bta-miR-195, bta-miR-339b, and bta-miR-199b, which were analyzed for target gene prediction. Gene Ontology (GO) and KEGG pathway analyses indicated that these miRNAs target genes involved in transcription regulation, ubiquitin-dependent endoplasmic reticulum-associated degradation (ERAD) pathways, and signalling pathways. Functional exploration revealed that these genes play roles in spermatogenesis, motility, acrosome reactions, and inflammatory responses. qPCR analysis showed that bta-miR-195 had 80% higher expression in HF spermatozoa compared to LF, suggesting its association with fertility status (p < 0.05). In conclusion, this study elucidates the miRNA cargoes in SP-EVs as indicators of Sahiwal bull fertility, highlighting bta-miR-195 as a potential fertility factor among the various miRNAs identified.

Effect of chemical pollution on the fertility of male rodents from natural populations: сomparing the response of sperm morphology, motility, and concentration

The results of studies of epididymal spermatozoa of three species of rodents (bank vole Clethrionomys glareolus, northern red-backed vole Cl. rutilus, and herb field mouse Sylvaemus uralensis) living under long-term exposure to atmospheric emissions from two large copper smelters in the Middle Urals are summarized (Middle Ural and Kirovgrad copper smelters). The impact of pollution (including at the individual level on the accumulation of Cu, Zn, Pb, and Cd in the liver) was assessed for indicators characterizing the quality of sperm from different aspects: morphology (proportion of cells with head and tail defects), motility (proportion of motile cells, velocity, and straightness of movement) and concentration. Sperm motility responds to pollution: in impact zones, the proportion of motile cells and their velocity were lower than in background zones. The occurrence of abnormal cells and sperm concentration were not statistically significantly different between impact and background zones. The reaction of sperm to chemical pollution is species-specific: voles react more strongly than the herb field mouse. The consistency of changes in sperm parameters (in the direction of their deterioration) in response to increased pollution was found only in the bank vole. Effect sizes for sperm parameters are much smaller compared to those for liver Cd accumulation and animal abundance. In general, the reaction of sperm to pollution turned out to be weak, none of the studied indicators can be a reliable marker of industrial pollution.

Defining lower esophageal sphincter physiomechanical states among esophageal motility disorders using functional lumen imaging probe panometry.

Functional lumen imaging probe (FLIP) panometry assesses esophageal motility in response to controlled volumetric distension. This study aimed to describe the physiomechanical states of the lower esophageal sphincter (LES) in response to serial filling/emptying regimes for esophageal motility disorders. Fourty-five patients with absent contractile response on FLIP and diagnoses of normal motility (n = 6), ineffective esophageal motility (IEM; n = 8), scleroderma (SSc; n = 10), or nonspastic achalasia (n = 21) were included, as were 20 patient controls with normal motility on FLIP and manometry. LES diameter and pressure were measured after stepwise FLIP filling at 60 mL, 70 mL, and emptying to 60 mL with relative changes used to define physiomechanical states. Passive dilatation after FLIP filling occurred in 63/65 (97%) patients among all diagnoses. After FLIP emptying, passive shortening occurred in 12/14 (86%) normal motility/IEM, 10/10 (100%) SSc, 9/21(43%) achalasia, and 16/20 (80%) controls, with auxotonic relaxation seen in 2/14 (14%) normal motility/IEM, 12/21 (57%) achalasia, and 4/20 (20%) controls. After achalasia treatment (LES myotomy), 21/21 (100%) achalasia had passive shortening after FLIP emptying. Physiomechanical states of the LES can be determined via response to FLIP filling and emptying regimes. While passive shortening was the general response to FLIP emptying, auxotonic relaxation was observed in achalasia, which was disrupted by LES myotomy. Further investigation is warranted into the clinical impact on diagnosis and treatment of esophageal motility disorders.

Lipidomic and Proteomic Insights from Extracellular Vesicles in Postmortem Dorsolateral Prefrontal Cortex Reveal Substance Use Disorder-Induced Brain Changes.

Substance use disorder (SUD) significantly increases the risk of neurotoxicity, inflammation, oxidative stress, and impaired neuroplasticity. The activation of inflammatory pathways by substances may lead to glial activation and chronic neuroinflammation, potentially mediated by the release of extracellular particles (EPs), such as extracellular condensates (ECs) and extracellular vesicles (EVs). These particles, which reflect the physiological, pathophysiological, and metabolic states of their cells of origin, might carry molecular signatures indicative of SUD. In particular, our study investigated neuroinflammatory signatures in SUD by isolating EVs from the dorsolateral prefrontal cortex (dlPFC) Brodmann's area 9 (BA9) in postmortem subjects. We isolated BA9-derived EVs from postmortem brain tissues of eight individuals (controls: n=4, SUD: n=4). The EVs were analyzed for physical properties (concentration, size, zeta potential, morphology) and subjected to integrative multi-omics analysis to profile the lipidomic and proteomic characteristics. We assessed the interactions and bioactivity of EVs by evaluating their uptake by glial cells. We further assessed the effects of EVs on complement mRNA expression in glial cells as well as their effects on microglial migration. No significant differences in EV concentration, size, zeta potential, or surface markers were observed between SUD and control groups. However, lipidomic analysis revealed significant enrichment of glycerophosphoinositol bisphosphate (PIP2) in SUD EVs. Proteomic analysis indicates downregulation of SERPINB12, ACYP2, CAMK1D, DSC1, and FLNB, and upregulation of C4A, C3, and ALB in SUD EVs. Gene ontology and protein-protein interactome analyses highlight functions such as cell motility, focal adhesion, and acute phase response signaling that is associated with the identified proteins. Both control and SUD EVs increased C3 and C4 mRNA expression in microglia, but only SUD EVs upregulated these genes in astrocytes. SUD EVs also significantly enhanced microglial migration in a wound healing assay.This study successfully isolated EVs from postmortem brains and used a multi-omics approach to identify EV-associated lipids and proteins in SUD. Elevated C3 and C4 in SUD EVs and the distinct effects of EVs on glial cells suggest a crucial role in acute phase response signaling and neuroinflammation.

Effects of Cholecystokinin on Esophageal Motor Response to Distension in Asymptomatic Volunteers.

Cholecystokinin (CCK) administration has been shown to reduce lower esophageal sphincter (LES) pressure in normal subjects in manometric studies. Functional luminal imaging probe (FLIP) panometry offers a method to assess esophageal motility in response to sustained distension though mechanisms related to this response remain unexplored. The aim of this study is to evaluate the effect of CCK-8 on the esophageal response to distension in asymptomatic volunteers using FLIP. Esophageal response to distension was studied in 7 asymptomatic volunteers (mean age ± SD [27 ± 2]; 86% female) before and after CCK-8 administration in a crossover study design. During sedated endoscopy, FLIP was performed twice with CCK-8 administered via intravenous push in one of 2 protocols: during filling (n = 4) or during emptying (n = 3). Esophagogastric junction distensibility index (EGJ-DI) at 60 mL fill volume and esophageal body contractile response patterns were analyzed. During the baseline FLIP study, all subjects had a contractile response with repetitive antegrade contractions both before and after CCK-8 administration. However, a sustained LES contraction or a sustained occluding contraction with esophageal shortening was observed in all subjects in the filling protocol, but in none during the emptying protocol. EGJ-DI was similar before and after CCK-8 during both filling (4.7 ± 1.9 mm2/mmHg vs 4.3 ± 1.8 mm2/mmHg) and emptying protocol (7.5 ± 1.4 mm2/mmHg vs 6.9 ± 0.6 mm2/mmHg). While EGJ-DI appeared unaffected by CCK-8 administration in asymptomatic volunteers, CCK induced spastic-reactive contractions of the LES during distention suggesting that exogenous CCK interferes with normal LES relaxation during secondary peristalsis.

The Posterior Insular Cortex is Necessary for Feeding-Induced Jejunal Myoelectrical Activity in Male Rats

The gastrointestinal tract exhibits coordinated muscle motility in response to food digestion, which is regulated by the central nervous system through autonomic control. The insular cortex is one of the brain regions that may regulate the muscle motility. In this study, we examined whether, and how, the insular cortex, especially the posterior part, regulates gastrointestinal motility by recording jejunal myoelectrical signals in response to feeding in freely moving male rats. Feeding was found to induce increases in jejunal myoelectrical signal amplitudes. This increase in the jejunal myoelectrical signals was abolished by vagotomy and pharmacological inhibition of the posterior insular cortex. Additionally, feeding induced a decrease and increase in sympathetic and parasympathetic nervous activities, respectively, both of which were eliminated by posterior insular cortical inhibition. These results suggest that the posterior insular cortex regulates jejunal motility in response to feeding by modulating autonomic tone.

Effect of Chemical Pollution on the Fertility of Male Rodents from Natural Populations: Сomparing the Response of Sperm Morphology, Motility, and Concentration

Effect of Chemical Pollution on the Fertility of Male Rodents from Natural Populations: Сomparing the Response of Sperm Morphology, Motility, and Concentration

Low concentrations of soybean lecithin nanoparticles had a positive impact on Holstein bulls' cryopreserved semen.

Spermatozoa can experience negative changes when subjected to freezing and thawing, including lowered motility, viability and acrosome response. Herein, the effects of different concentrations of soybean lecithin nanoparticles on cryopreserved Holstein bull semen were examined. Semen was collected, cryopreserved and utilized for sperm kinetic parameter analysis following dilution, equilibration and thawing with 0.5% soybean lecithin (E1), the control extender, and 0.75% (E2), 0.5% (E3), 0.25% (E4) and 0.125% (E5) of lecithin nanoparticles. Results revealed that following dilution, the progressive motility (PM) at E3, E4 and E5 of lecithin nanoparticles was higher (p < .05) than it was for E2. After equilibration, compared to the E1, E2, and E3 values, the PM, vitality, normal morphology, membrane integrity and intact acrosome values at the E5 were consistently greater (p < .05). Comparing the percentages of intact acrosome and membrane integrity at E2 and E3 to E4 and E5, a substantial decrease (p < .05) was seen. Following thawing, the percentage of PM improved at E2 and E5, even though their mean PM values were similar (p > .05) compared to E1, E3 and E4. Vigour and progression parameters of sperm (DAP, DCL, DSL, VAP, VCL, VSL and STR) at E5 were higher (p < .05) than those at E1, E2, E3 and E4. In conclusion, the cryopreserved sperm from Holstein bulls revealed outstanding properties both after equilibration and after thawing with 0.125% lecithin nanoparticles, and they were sensitive to high dosages.

Roles of DJ41_1407 and DJ41_1408 in Acinetobacter baumannii ATCC19606 Virulence and Antibiotic Response.

Acinetobacter baumannii is a major cause of nosocomial infections, and its highly adaptive nature and broad range of antibiotic resistance enable it to persist in hospital environments. A. baumannii often employs two-component systems (TCSs) to regulate adaptive responses and virulence-related traits. This study describes a previously uncharacterized TCS in the A. baumannii ATCC19606 strain, consisting of a transcriptional sensor, DJ41_1407, and its regulator, DJ41_1408, located adjacent to GacA of the GacSA TCS. Markerless mutagenesis was performed to construct DJ41_1407 and DJ41_1408 single and double mutants. DJ41_1408 was found to upregulate 49 genes and downregulate 43 genes, most of which were associated with carbon metabolism and other metabolic pathways, such as benzoate degradation. MEME analysis revealed a putative binding box for DJ41_1408, 5'TGTAAATRATTAYCAWTWAT3'. Colony size, motility, biofilm-forming ability, virulence, and antibiotic resistance of DJ41_1407 and DJ41_1408 single and double mutant strains were assessed against wild type. DJ41_1407 was found to enhance motility, while DJ41_1408 was found to upregulate biofilm-forming ability, and may also modulate antibiotic response. Both DJ41_1407 and DJ41_1408 suppressed virulence, based on results from a G. mellonella infection assay. These results showcase a novel A. baumannii TCS involved in metabolism, with effects on motility, biofilm-forming ability, virulence, and antibiotic response.

Abstract 5694: Elucidating areca nut-induced miRNA-mRNA regulatory networks in head and neck cancer pathogenesis

Abstract Areca nut has been considered a high-risk carcinogen for head and neck cancer (HNC) in Southeast Asia, while its molecular effects, especially on the miRNA regulatory roles, remain elusive. This study characterized miRNA-mRNA networks associated with areca nut-related HNC. We integratively analyzed the areca nut-induced mRNA profile and TCGA-HNSC gene set. A total of 2575 genes were identified, with 1971 upregulated and 604 downregulated in cancers. The KEGG pathway analysis revealed that these genes were enriched in the cellular functions related to motility and stress response. Experimental studies confirmed that arecoline promoted cell migration, invasion, and chemo-radioresistance. We further cross-analyzed the miRNAs induced by areca nut and dysregulated in TCGA-HNSC data and defined 71 molecules affected, with 35 upregulation and 36 downregulation. Using the multimiR tool to map potential mRNA-miRNA interactions, we uncovered that these miRNAs were connected to 2173 genes. These molecules participated in several oncogenic mechanisms, such as ErbB and PI3K-Akt signaling, cell adhesion, and DNA damage response. We endeavored to establish miRNA-mRNA interaction networks with the functions of cellular motility and stress response via the Cytoscape analytical method. Our data revealed nexus comprising 41 miRNAs with 83 mRNAs, and 38 miRNAs with 66 mRNAs, respectively, co-regulate these two malignant functions. A key miRNA, miR-410-3p, downregulated in HNC and decreased following areca nut treatment, was studied. Ectopic expression of miR-410-3p attenuated areca nut-induced cell invasion and exerted modulatory effects on its target oncogenes, CRK. Thus, our study delineates a comprehensive view of the miRNA-mRNA interplay altered by areca nut, illustrating a sophisticated mechanism of carcinogenesis and suggesting new avenues for diagnostic and therapeutic strategies in HNC. Citation Format: Hung-Han Huang, Guo-Rung You, Kai-Hsin Lin, Yin-Ju Chen, Ann-Joy Cheng. Elucidating areca nut-induced miRNA-mRNA regulatory networks in head and neck cancer pathogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5694.

APOE4 genotype and aging impair injury-induced microglial behavior in brain slices, including toward Aβ, through P2RY12

Microglia are highly dynamic cells that play a critical role in tissue homeostasis through the surveillance of brain parenchyma and response to cues associated with damage. Aging and APOE4 genotype are the strongest risk factors for Alzheimer’s disease (AD), but how they affect microglial dynamics remains unclear. Using ex vivo confocal microscopy, we analyzed microglial dynamic behaviors in the entorhinal cortex (EC) and hippocampus CA1 of 6-, 12-, and 21-month-old mice APOE3 or APOE4 knock-in mice expressing GFP under the CX3CR1 promoter. To study microglia surveillance, we imaged microglia baseline motility for 20 min and measured the extension and retraction of processes. We found that APOE4 microglia exhibited significantly less brain surveillance (27%) compared to APOE3 microglia in 6-month-old mice; aging exacerbated this deficit. To measure microglia response to damage, we imaged process motility in response to ATP, an injury-associated signal, for 30 min. We found APOE4 microglia extended their processes significantly slower (0.9 µm/min, p < 0.005) than APOE3 microglia (1.1 μm/min) in 6-month-old animals. APOE-associated alterations in microglia motility were observed in 12- and 21-month-old animals, and this effect was exacerbated with aging in APOE4 microglia. We measured protein and mRNA levels of P2RY12, a core microglial receptor required for process movement in response to damage. We found that APOE4 microglia express significantly less P2RY12 receptors compared to APOE3 microglia despite no changes in P2RY12 transcripts. To examine if the effect of APOE4 on the microglial response to ATP also applied to amyloid β (Aβ), we infused locally Hi-Lyte Fluor 555-labeled Aβ in acute brain slices of 6-month-old mice and imaged microglia movement for 2 h. APOE4 microglia showed a significantly slower (p < 0.0001) process movement toward the Aβ, and less Aβ coverage at early time points after Aβ injection. To test whether P2RY12 is involved in process movement in response to Aβ, we treated acute brain slices with a P2RY12 antagonist before Aβ injection; microglial processes no longer migrated towards Aβ. These results provide mechanistic insights into the impact of APOE4 genotype and aging in dynamic microglial behaviors prior to gross Aβ pathology and could help explain how APOE4 brains are more susceptible to AD pathogenesis.

Abstract PR-005: CAR T-cell motility response to interstitial fluid flow and tumor microenvironment

Abstract PR-005: CAR T-cell motility response to interstitial fluid flow and tumor microenvironment

The impact of 48 h high carbohydrate diets with high and low FODMAP content on gastrointestinal status and symptoms in response to endurance exercise, and subsequent endurance performance.

This study investigated the effects of a high carbohydrate diet, with varied fermentable oligo-, di-, and mono-saccharide and polyol (FODMAP) content, before endurance exercise on gastrointestinal integrity, motility, and symptoms; and subsequent exercise performance. Twelve endurance athletes were provided with a 48 h high carbohydrate (mean±SD: 12.1±1.8 g kg day-1) diet on two separate occasions, composed of high (54.8±10.5 g day-1) and low FODMAP (3.0±0.2 g day-1) content. Thereafter, participants completed a 2 h steady-state running exercise at 60% of (22.9±1.2 °C, 46.4±7.9% RH), followed by a 1 h distance performance test. Pre-exercise and every 20 min during steady-state exercise, 100 mL maltodextrin (10%w/v) solution was consumed. A 150 mL lactulose (20 g) solution was consumed 30 min into the distance performance test to determine orocecal transit time (OCTT) during exercise. Blood was collected pre- and post exercise to determine gastrointestinal integrity biomarkers (i.e., I-FABP, sCD14, and CRP). Breath hydrogen (H2) and gastrointestinal symptoms (GIS) were determined pre-exercise, every 15 min, during and throughout recovery. No differences in gastrointestinal integrity biomarkers, OCTT, or distance completed were observed between trials. Pre-exercise total-GIS (1.3±2.9vs. 4.3±4.4), gut discomfort (9.9±8.1vs. 15.8±9.0), and upper-GIS (2.8±2.6vs. 5.7±4.8) during exercise were less severe on high carbohydrate low FODMAP (HC-LFOD) versus high carbohydrate high FODMAP (HC-HFOD) (p<0.05). Gut discomfort (3.4±4.4vs. 0.2±0.6) and total-GIS (4.9±6.8vs. 0.2±0.6) were higher during recovery on HC-LFOD versus HC-HFOD (p<0.05). The FODMAP content of a 48 h high carbohydrate diet does not impact gastrointestinal integrity or motility in response to endurance exercise. However, a high FODMAP content exacerbates GIS before and during exercise, but this does not impact performance outcomes.

The Photoprotective Behavior of a Motile Benthic Diatom as Elucidated from the Interplay Between Cell Motility and Physiological Responses to a Light Microgradient Using a Novel Experimental Setup

It has long been hypothesized that benthic motile pennate diatoms use phototaxis to optimize photosynthesis and minimize photoinhibitory damage by adjusting their position within vertical light gradients in coastal benthic sediments. However, experimental evidence to test this hypothesis remains inconclusive, mainly due to methodological difficulties in studying cell behavior and photosynthesis over realistic spatial microscale gradients of irradiance and cell position. In this study, a novel experimental approach was developed and used to test the hypothesis of photosynthesis optimization through motility, based on the combination of single-cell in vivo chlorophyll fluorometry and microfluidic chips. The approach allows the concurrent study of behavior and photosynthetic activity of individual cells of the epipelic diatom species Craspedostauros britannicus exposed to a light microgradient of realistic dimensions, simulating the irradiance and distance scales of light microgradients in benthic sediments. Following exposure to light, (i) cells explored their light environment before initiating light-directed motility; (ii) cells used motility to lower their light dose, when exposed to the highest light intensities; and (iii) motility was combined with reversible non-photochemical quenching, to allow cells to avoid photoinhibition. The results of this proof-of-concept study not only strongly support the photoprotective nature of photobehavior in the studied species but also revealed considerable variability in how individual cells reacted to a light microgradient. The experimental setup can be readily applied to study motility and photosynthetic light responses of other diatom species or natural assemblages, as well as other photoautotrophic motile microorganisms, broadening the toolset for experimental microbial ecology research.

Real-time imaging of pressure response of bacterial motility

Real-time imaging of pressure response of bacterial motility

Fighting Microbial Infections from Escherichia coli O157:H7: The Combined Use of Three Essential Oils of the Cymbopogon Genus and a Derivative of Esculentin-1a Peptide.

The absence of effective therapy against Escherichia coli O157:H7 infections has led to the need to develop new antimicrobial agents. As the use of synergistic combinations of natural antimicrobial compounds is growing as a new weapon in the fight against multidrug-resistant bacteria, here, we have tested new synergistic combinations of natural agents. Notably, we investigated a possible synergistic effect of combinations of essential oils and natural peptides to counteract the formation of biofilm. We chose three essential oils (i.e., Cymbopogon citratus, C. flexuosus and C. martinii) and one peptide already studied in our previous works. We determined the fractional inhibitory concentration (FIC) by analyzing the combination of the peptide derived from esculentin-1a, Esc(1-21), with the three essential oils. We also studied the effects of combinations by time-kill curves, scanning electron microscopy on biofilm and Sytox Green on cell membrane permeability. Finally, we analyzed the expression of different genes implicated in motility, biofilm formation and stress responses. The results showed a different pattern of gene expression in bacteria treated with the mixtures compared to those treated with the peptide or the single C. citratus essential oil. In conclusion, we demonstrated that the three essential oils used in combination with the peptide showed synergy against the E. coli O157:H7, proving attractive as an alternative strategy against E. coli pathogen infections.