Community structure and carbon metabolism functions of bacterioplankton in the Guangdong coastal zone.

Coastal ecosystems are an important region for biogeochemical cycling, are a hotspot of anthropogenic disturbance and play a crucial role in global carbon cycling through the metabolic activities of bacterioplankton. Bacterioplankton can be broadly classified into two lifestyles: free-living (FL) and particle-attached (PA). However, how coastal bacterioplankton the community structure, co-occurrence networks and carbon metabolic functions with different lifestyles are differentiated is still largely unknown. Understanding these processes is necessary to better determine the contributions of coastal bacterioplankton to carbon cycling. Here, the characteristics of community structure and carbon metabolism function of bacterioplankton with two lifestyles in the coastal areas of Guangdong Province were investigated using amplicon sequencing, metagenomic, and metatranscriptomic techniques. The results show that the main bacterioplankton responsible for carbon metabolism were the Pseudomonadota, Bacteroidota, and Actinomycetota. The microbial community structure, carbon metabolic function, and environmental preferences differ between different lifestyles. FL and PA bacteria exhibited higher carbon fixation and degradation potentials, respectively. A range of environmental factors, such as dissolved oxygen, pH, and temperature, were associated with the community structure and carbon metabolic functions of the bacterioplankton. Human activities, such as nutrient discharge, may affect the distribution of functional genes and enhance the carbon degradation functions of bacterioplankton. In conclusion, this study increased the understanding of the role of microorganisms in regulating carbon export in coastal ecosystems with intense human activity. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-024-00245-x.

Co-occurrence between key HAB species and particle-attached bacteria and substrate specificity of attached bacteria in the coastal ecosystem.

The ecological dynamics of particle-attached bacteria (PAB) were observed through changes in the core phytoplankton phycosphere, and were associated with the dynamics of free-living bacteria (FLB) using metabarcoding and microscopic analyses over 210 days (with weekly sampling intervals) in the Jangmok coastal ecosystem, South Korea. Cluster analysis and non-metric multidimensional scaling classified the phytoplankton community into six groups comprising core phytoplankton species, including the harmful algal species Akashiwo sanguinea (dinoflagellate) in late autumn, Teleaulax amphioxeia (cryptomonads) in early winter and spring, Skeletonema marinoi-dohrnii complex (diatom) in winter, Pseudo-nitzschia delicatissima (diatom) in early spring, and diatom complexes such as Chaetoceros curvisetus and Leptocylindrus danicus in late spring. We identified 59 and 32 indicators in PAB and FLB, respectively, which rapidly changed with the succession of the six core phytoplankton species. The characteristics of PAB were mainly divided into "Random encounters" or "Attraction of motivation by chemotaxis." When Akashiwo sanguinea bloomed, bacteria of the genera Kordiimonas and Polaribacter, which are commonly observed in PAB and FLB, indicated "Random encounter" characteristics. In addition, Sedimenticola of PAB was uniquely presented in Akashiwo sanguinea, exhibiting characteristics of "Attraction of motivation by chemotaxis." In contrast, FLB followed the strategy of "Random encounters" because it was not affected by specific habitats and energy sources. Thus, many common bacteria were PAB and FLB, thereby dictating the bacteria's strategy of "Random encounters." "Attraction of motivation by chemotaxis" has characteristics of the species-specific interactions between PAB and specific harmful algal species, and is potentially influenced by organic matter of core phytoplankton cell surface and/or EPS released from phytoplankton.

Therapeutic glycan-specific antibody binding mediates protection during primary amoebic meningoencephalitis.

Naegleria fowleri (N. fowleri) infection via the upper respiratory tract causes a fatal CNS disease known as primary amoebic meningoencephalitis (PAM). The robust in vivo immune response to N. fowleri infection underlies the immunopathology that characterizes the disease. However, little is known about why this pathogen evades immune control. Infections occur in seemingly healthy individuals and effective clinical options are lacking, thus a nearly 98% fatality rate. It is unclear how or if host factors may contribute to susceptibility or disease exacerbation, yet mechanistic studies of the in vivo immune response and disease progression are hampered by a lack of tools. In this study, we have generated monoclonal antibodies to N. fowleri surface antigens and shown them to be excellent tools for studying the in vivo immune response. We also identified one monoclonal, 2B6, with potent inherent anti-amoebastatic activity in vitro. This antibody is also able to therapeutically prolong host survival in vivo and furthermore, recombinant antibodies with an isotype more capable of directing immune effector activity further improved survival when given therapeutically. Thus, we report the generation of a novel monoclonal antibody to N. fowleri that can enhance beneficial immune functions, even when given therapeutically during disease. We believe this provides evidence for the potential of therapeutic antibody treatments in PAM.IMPORTANCENaegleria fowleri (N. fowleri) is a free-living amoeba that is found ubiquitously in warm freshwater. While human exposure is common, it rarely results in pathogenesis. However, when N. fowleri gains access to the upper airway, specifically the olfactory mucosa, infection leads to a lethal disease known as primary amoebic meningoencephalitis (PAM). As a free-living amoeba, N. fowleri does not need a mammalian host; indeed, it can be accurately described as an accidental opportunistic pathogen. While most opportunistic infections occur in humans who are immunocompromised, there are no reported immune dysfunctions associated with N. fowleri infection. Therefore, the basis for N. fowleri opportunism is not known, and the reasons why some humans develop PAM while others do not are simply not well understood. It is reasonable to speculate that local or acute immune failures, potentially even a lack of prior adaptive immunity, are related to disease susceptibility. Careful immune profiling and characterization of the in vivo immune response to N. fowleri in a mammalian host are desperately needed to understand which host factors are critical to defense, and how these responses might be compromised in a way that results in lethal infection. To identify genes and pathways that provide resistance against in vivo N. fowleri infection, we generated surface reactive monoclonal antibodies (Abs) that provide rapid amoeba detection and quantification in vivo. Interestingly, N. fowleri binding Abs have been readily detected in the serum and saliva of humans and animals suggesting that non-lethal exposure drives a humoral immune response against the amoeba. Yet, how Abs might interact with Naegleria in vivo or contribute to preventing lethal infection is not well understood. In this study, we have generated and characterized a monoclonal antibody (Ab), Clone 2B6, that recognizes a glycosylated surface antigen present in cultured in vitro N. fowleri as well as mouse passaged N. fowleri. When clone 2B6 binds to N. fowleri, it inhibits amoeba motility and feeding behavior, leading to strong growth inhibition. Mice treated systemically and intracerebrally with Ab displayed a delayed disease onset and prolonged survival. In addition, we found that enhancing immune-directed effector activity via antibody isotype could further enhance survival without obvious immunopathogenic side effects. These findings show the potential for antibody treatment as an additional therapeutic to those used currently in PAM.

Do Repeated Respiratory Tract Infections Predispose to Amoebic Meningoencephalitis Caused by Free-Living Amoebae?

Recent reports of fatal meningoencephalitis from Kerala, South India, are creating ripples among medical and health administrations. Free-living amoebae (FLA) have been attributed to these infections. Despite their free-living nature, these amoebae have been recognized as potential opportunistic organisms that occasionally cause infections in immunocompetent and immunocompromised individuals. The pathophysiology, epidemiology, and clinical course of diseases caused by FLA are not completely understood. Exposure to humans and animals is imminent given their presence in the air, water, and soil. Human infections, although infrequent, can lead to severe morbidity and mortality as evidenced by the recently emerging reports from Kerala, South India. Since these infections were noticed among children, it is unlikely that they were immunocompromised. Therefore, in this editorial, we speculate on the possibility of frequent upper respiratory tract viral infections as predisposing factors for infection with FLA.

Vermamoeba vermiformis as the etiological agent in a patient with suspected non-Acanthamoeba keratitis.

Vermamoeba vermiformis (V. vermiformis) is one of the most common free-living amoeba (FLA) and is frequently found in environments such as natural freshwater areas, surface waters, soil, and biofilms. V. vermiformis has been reported as a pathogen with pathogenic potential for humans and animals. The aim is to report a case of non-Acanthamoeba keratitis in which V. vermiformis was the etiological agent, identified by culture and molecular techniques. Our case was a 48-year-old male patient with a history of trauma to his eye 10 days ago. The patient complained of eye redness and purulent discharge. A slit-lamp examination of the eye revealed a central corneal ulcer with peripheral infiltration extending into the deep stroma. The corneal scraping sample taken from the patient was cultured on a non-nutritious agar plate (NNA). Amoebae were evaluated according to morphological evaluation criteria. It was investigated by PCR method and confirmed by DNA sequence analysis. Although no bacterial or fungal growth was detected in the routine microbiological evaluation of the corneal scraping sample that was cultured, amoeba growth was detected positively in the NNA culture. Meanwhile, Acanthamoeba was detected negative by real-time PCR. However, V. vermiformis was detected positive with the specific PCR assay. It was confirmed by DNA sequence analysis to be considered an etiological pathogenic agent. Thus, topical administration of chlorhexidine gluconate %0.02 (8 × 1) was initiated. Clinical regression was observed 72 h after chlorhexidine initiation, and complete resolution of keratitis with residual scarring was noticed in 5 weeks. In conclusion, corneal infections due to free-living amoebae can occur, especially in poor hygiene. Although Acanthamoeba is the most common keratitis due to amoeba, V. vermiformis is also assumed to associate keratitis in humans. Clinicians should also be aware of other amoebic agents, such as V. vermiformis, in keratitis patients.

First report of Acanthamoeba spp. isolation in a recreational hot spring in the Philippines.

Natural hot springs are ideal places and environmental matrices that offer relaxation to people and microorganisms of different types. A total of 40 surface water samples were collected from the five identified collection sites, eight water samples for each site. Collection sites are designated 200 m apart to cover the entire study site. Surface water samples were collected approximately 10-20 cm from the surface. Water samples were filtered, cultured, and microscopically observed for 14 days. After 14 days of cultivation, eight (20%) water samples revealed cystic and trophozoite stages. Polymerase chain reaction using JDP1 and JDP2 specific primers confirmed the presence of Acanthamoeba spp. from two of our isolates in the hot spring, isolates 1.1 and 5.1. Further sequencing revealed that the isolates are Acanthamoeba T20 and Acanthamoeba genotype T7. Sequences were deposited to GenBank and were assigned accession numbers PP741726 and PP741727, respectively. The isolation of Acanthamoeba spp. in hot springs has significant health implications, especially for those who use it for recreational activity. Private resort owners are highly encouraged to regularly monitor and maintain hot spring resorts to avoid future infections.

Isolates of Acanthamoeba species in the marine environment in the Philippines.

Acanthamoebae spp. are considered the most commonly occurring free-living amoebae (FLA) in the environment. Their high resilience enables them to thrive in different types of environments. Using purposive sampling, 80 surface water samples were collected from identified coastal sites in Mariveles, Bataan, and Lingayen Gulf (40 water samples for each). Nineteen (23.75%) of the 80 water samples yielded positive amoebic growth during the 14-day culture and microscopic examination. The polymerase chain reaction confirmed Acanthamoeba spp. DNA in isolates MB1, A3, A4, A7, C5, and D3 using JDP1 and JDP2 primer sets. Further sequencing revealed that the isolates belonged to Acanthamoeba sp., Acanthamoeba culbertsoni, Acanthamoeba castellani, and Acanthamoeba genotype T4. The sequences were deposited in GenBank and registered under accession numbers PP741651, PP767364, PP741728, PP741729, PP767365, and PP767366, respectively. Potential risk factors such as waste disposal, expansion of human settlements to coastal locations, and soil runoffs in these environments should be controlled to mitigate the proliferation of potentially pathogenic strains of FLAs.

Diversity of Anaplasmataceae Transmitted by Ticks (Ixodidae) and the First Molecular Evidence of Anaplasma phagocytophilum and Candidatus Anaplasma boleense in Paraguay.

Anaplasmataceae bacteria are emerging infectious agents transmitted by ticks. The aim of this study was to identify the molecular diversity of this bacterial family in ticks and hosts, both domestic and wild, as well as blood meal sources of free-living ticks in northeastern Paraguay. The bacteria were identified using PCR-HRM, a method optimized for this purpose, while the identification of ticks and their blood meal was performed using conventional PCR. All amplified products were subsequently sequenced. The bacteria detected in the blood hosts included Ehrlichia canis, Anaplasma platys, and Anaplasma phagocytophilum, Candidatus Anaplasma boleense, and Wolbachia spp., which had not been previously reported in the country. Free-living and parasitic ticks on dogs (Canis lupus familiaris) and wild armadillos (Dasypus novemcinctus) were collected and identified as Rhipicephalus sanguineus and Amblyomma spp. The species E. canis, A. platys, A. phagocytophilum, and Ca. A. boleense were detected in domestic dog ticks, and E. canis and A. platys were found for the first time in armadillos and free-living ticks. Blood feeding sources detected in free-living ticks were rodents, humans, armadillos and dogs. Results show a high diversity of tick-borne pathogens circulating among domestic and wild animals in the northeastern region of Paraguay.

Adjustability of gait speed in clinics and free-living environments in people with Parkinson's disease.

Objective: Gait speed is regulated by varying gait parameters depending on the diverse contexts of the environment. People with Parkinson's disease (PwPD) have difficulty in adapting to gait control in their environment; however, the relationship between gait speed and spatiotemporal parameters in free-living environments has not been clarified. This study aimed to compare gait parameters according to gait speed in clinics and free-living environments. Methods: PwPD were assessed at the clinic and in a free-living environment using an accelerometer on the lower back. By fitting a bimodal Gaussian model to the gait speed distribution, gait speed was divided into lower and higher speeds. We compared the spatiotemporal gait parameters using a 22 (environment [clinic/free-living]  speed [lower/higher]) repeated-measures analysis of variance. Associations between Parkinson's disease symptoms and gait parameters were evaluated using Bayesian Pearson's correlation coefficients. Results: In the 41 PwPD included in this study, spatiotemporal gait parameters were significantly worse in free-living environments than in clinics and at lower speeds than at higher speeds. The fit of the walking speed distribution to the bimodal Gaussian model (adjustability of gait speed) in free-living environments was related to spatiotemporal gait parameters, severity of Parkinson's disease, number of falls, and quality of life. Conclusions: The findings suggest that gait control, which involves adjusting gait speed according to context, differs between clinics and free-living environments in PwPD. Gait assessment for PwPD in both clinical and free-living environments should interpret gait impairments in a complementary manner.

Diversity of Free-Living Amoebae in New Zealand Groundwater and Their Ability to Feed on Legionella pneumophila.

Free-living amoebae (FLA) are common in both natural and engineered freshwater ecosystems. They play important roles in biofilm control and contaminant removal through the predation of bacteria and other taxa. Bacterial predation by FLA is also thought to contribute to pathogen dispersal and infectious disease transmission in freshwater environments via the egestion of viable bacteria. Despite their importance in shaping freshwater microbial communities, the diversity and function of FLA in many freshwater ecosystems are poorly understood. In this study, we isolated and characterized FLA from two groundwater sites in Canterbury, New Zealand using microbiological, microscopic, and molecular techniques. Different methods for groundwater FLA isolation and enrichment were trialed and optimized. The ability of these isolated FLA to predate on human pathogen Legionella pneumophila was assessed. FLA were identified by 18S metagenomic amplicon sequencing. Our study showed that Acanthamoeba spp. (including A. polyphaga) and Vermamoeba veriformis were the main FLA species present in both groundwater sites examined. While most of the isolated FLA co-existed with L. pneumophila, the FLA populations in the L. pneumophila co-culture experiments predominantly consisted of A. polyphaga, Acanthamoeba spp., Naegleria spp., V. vermiformis, Paravahlkampfia spp., and Echinamoeba spp. These observations suggest that FLA may have the potential to act as reservoirs for L. pneumophila in Canterbury, New Zealand groundwater systems and could be introduced into the local drinking water infrastructure, where they may promote the survival, multiplication, and dissemination of Legionella. This research addresses an important gap in our understanding of FLA-mediated pathogen dispersal in freshwater ecosystems.

Approaches for Targeting Naegleria fowleri Using Nanoparticles and Artificial Peptides.

Naegleria fowleri is a free-living amoeba which causes primary amoebic meningoencephalitis (PAM). Although PAM is rare, the fatality rate is staggering at over 97%. So, the importance of finding an effective treatment and cure for PAM caused by N. fowleri is a crucial area of research. Existing research on developing novel therapeutic strategies to counter N. fowleri infection is limited. Since the blood-brain barrier (BBB) presents an obstacle to delivering drugs to the site of infection, it is important to employ strategies that can effectively direct the therapeutics to the brain. In this regard, our review focuses on understanding the physiology and mechanisms by which molecules pass through the BBB, the current treatment options available for PAM, and the recent research conducted in the decade of 2012 to 2022 on the use of nanomaterials to enhance drug delivery. In addition, we compile research findings from other central nervous system (CNS) diseases that use shuttle peptides which allow for transport of molecules through the BBB. The approach of utilizing BBB shuttles to administer drugs through the BBB may open up new areas of drug discovery research in the field of N. fowleri infection.

Two new species of the genus Halichoanolaimus (Nematoda, Selachinematidae) from the intertidal zone of the Yellow Sea, China.

Two new marine nematode species belonging to the genus Halichoanolaimus from the intertidal zone of the Yellow Sea are described. Halichoanolaimussinensis sp. nov. is characterized by amphideal fovea with 2.5-3.0 turns, 20-27% of corresponding body diameters; spicules curved, middle portion broad, tapering distally, 1.4-1.5 cloacal body diameters long; gubernaculum slender consisting of two detached lateral pieces tapering distally; 10-13 papilliform precloacal supplements in two groups, the posterior three supplements smaller and closer to each other, the remaining supplements larger and widely spaced; tail conico-cylindrical with a half cylindrical portion. The second new species, Halichoanolaimuszhangi sp. nov. is distinct by having lateral differentiation present except in anterior half of pharynx which has even punctations, amphideal fovea with 3.0-3.3 turns, spicules curved, gradually narrowing from proximal to distal end with pointed tip, 7 papilliform precloacal supplements, gradually increasing the spacing distance forward, two rows of subventral conical setae situated at the precloacal region, tail elongated, filiform. An updated key to 30 valid species of Halichoanolaimus is provided.

THE 72-KDA PROTEIN OF NAEGLERIA FOWLERI PLAYS AN IMPORTANT ROLE IN THE ADHESION OF TROPHOZOITES TO BALB/C MICE NASAL EPITHELIUM.

Naegleria fowleri is a protozoan that causes primary amebic meningoencephalitis (PAM). The infection occurs when the trophozoites enter the nasal cavity, adhere to the nasal mucosa, invade the epithelium, and migrate until they reach the olfactory bulb. Like other pathogens, there is evidence that the adhesion of N. fowleri to host cells is an important factor in the process of cytopathogenicity and disease progression. However, the factors involved in the adhesion of the pathogen to the cells of the nasal epithelium have not been characterized. The objective of this study was to identify a protein on the surface of N. fowleri, which could act as adhesin to the mouse nasal epithelium in the PAM model. The interaction between proteins of extracts of N. fowleri and cells of the nasal epithelium of BALB/c mice was analyzed using overlay and Western blot assays. A 72-kDa band of N. fowleri interacted directly with epithelial cell proteins, this polypeptide band was purified and analyzed by mass spectrometry. Analysis revealed that polypeptide bands of 72 kDa contained peptides that matched the membrane protein, actin 1 and 2, and Hsp70. Moreover, the N. fowleri extracts resolved in 2D-SDS-PAGE showed that 72-kDa spot interacted with proteins of mouse epithelial cells, which include characteristics of the theoretical data of molecular weight and pH obtained in the analysis by mass spectrometry. Immunofluorescence tests showed that this protein is located on the surface of trophozoites and plays an important role in the adhesion of amoeba either in vitro or in vivo assays, suggesting that this protein contributes during the N. fowleri invasion and migration to the brain, causing primary amoebic meningoencephalitis.

Isolation and Molecular Identification of Vahlkampfiidae and Vermamoeba Vermiformis from Fresh Vegetables: A Neglected Source of Infections.

Background: Naegleria spp., Tetramitus spp., and Vermamoeba vermiformis are potential pathogenic free-living amoebae (FLA) causing diseases such as keratitis, meningoencephalitis, and lung infections. We aimed to investigate the presence of Vahlkampfiidae and V. vermiformis in raw vegetables commonly consumed in Iran. Methods: Totally, 70 samples of vegetables samples including watercress (22), leeks (12), parsley (10), basil (13) and mint (13) were collected from municipal markets of Tehran, the capital of Iran during June to October 2021. After washing vegetables, samples were cultivated onto 2% non-nutrient agar (NNA) medium. After morphological confirmations, DNA was extracted and identical fragments of the FLA were amplified and sequenced. Results: Out of 70 cultured samples, 11 samples (15.71 %) were morphologically positive, of which four and seven were V. vermiformis and Vahlkampfiidae isolates, respectively. According to the PCR/sequencing results two, one, one, and one strains belonged to N. australiensis, N. americana, Vahlkampfia sp., V. inornata, and T. aberdonicus, respectively. All Vermamoeba genus were characterized as V. vermiformis. Conclusion: The results of current study revealed the contamination of fresh raw vegetables with Vahlkampfiidae and V. vermiformis. In addition, to our knowledge this is the first report of T. aberdonicus in raw vegetables. Our findings highlight the public health importance of vegetables in transmission of FLA, as well as the potential role of FLA in transmission of potential pathogenic microorganisms via consuming of fresh raw vegetables.

Social life of free-living amoebae in aquatic environment- comprehensive insights into interactions of free-living amoebae with neighboring microorganisms.

Free-living amoebae (FLA) are prevalent in nature and man-made environments, and they can survive in harsh conditions by forming cysts. Studies have discovered that some FLA species are able to show pathogenicity to human health, leading to severe infections of central nervous systems, eyes, etc. with an extremely low rate of recovery. Therefore, it is imperative to establish a surveillance framework for FLA in environmental habitats. While many studies investigated the risks of independent FLA, interactions between FLA and surrounding microorganisms determined microbial communities in ecosystems and further largely influenced public health. Here we systematically discussed the interactions between FLA and different types of microorganisms and corresponding influences on behaviors and health risks of FLA in the environment. Specifically, bacteria, viruses, and eukaryotes can interact with FLA and cause either enhanced or inhibited effects on FLA infectivity, along with microorganism community changes. Therefore, considering the co-existence of FLA and other microorganisms in the environment is of great importance for reducing environmental health risks.

Mycorrhizal association controls soil carbon-degrading enzyme activities and soil carbon dynamics under nitrogen addition: A systematic review.

Recent evidence suggests that changes in carbon-degrading extracellular enzyme activities (C-EEAs) can help explain soil organic carbon (SOC) dynamics under nitrogen (N) addition. However, the factors controlling C-EEAs remain unclear, impeding the inclusion of microbial mechanisms in global C cycle models. Using meta-analysis, we show that the responses of C-EEAs to N addition were best explained by mycorrhizal association across a wide range of environmental and experimental factors. In ectomycorrhizal (ECM) dominated ecosystems, N addition suppressed C-EEAs targeting the decomposition of structurally complex macromolecules by 13.1 %, and increased SOC stocks by 5.2 %. In contrast, N addition did not affect C-EEAs and SOC stocks in arbuscular mycorrhizal (AM) dominated ecosystems. Our results indicate that earlier studies may have overestimated SOC changes under N addition in AM-dominated ecosystems and underestimated SOC changes in ECM-dominated ecosystems. Incorporating this mycorrhizal-dependent impact of EEAs on SOC dynamics into Earth system models could improve predictions of SOC dynamics under environmental changes.

What Really Matters?: How Insulin Dose, Timing, and Distribution Relate to Meal Composition in Free-Living People with Type 1 Diabetes.

Optimizing postprandial glucose control in persons with type 1 diabetes (T1D) is challenging. We hypothesized that in free-living individuals, meal composition (high and low glycemic index [HGI and LGI], high and low fat [HF and LF]) may impact insulin requirements. Adults (N = 25) with T1D using open-loop insulin and continuous glucose monitoring were provided a meal-tagging app and prepackaged meals with defined macronutrient content. Data from 463 meals were analyzed. LGI meals required significantly more insulin than HGI meals (P = 0.01). Furthermore, the mean (±standard deviation) carbohydrate-to-insulin ratio (CIR) was significantly different overall among the LGI-LF (5.5 ± 3.4), LGI-HF (4.5 ± 3.8), HGI-LF (7.6 ± 5.1), and HGI-HF (8.7 ± 5.8) meals (P = 0.001). The risk of nocturnal hypoglycemia is associated with daytime hypoglycemia and amount of insulin administered prior to the evening and exercise. This exploratory study designed to examine the impact of different meal types on insulin dosing requirements in free-living adults with T1D emphasizes the need for individualized adjustment of the CIR depending on meal composition.

Gait kinematics differ by bout duration and setting.

BACKGROUND: Gait kinematics differ between settings and among young and older adults with and without knee osteoarthritis. Out-of-lab data has a variety of walking bout characteristics compared to controlled in-lab settings. The effect of walking bout duration on gait analysis results is unclear, and there is no standardized procedure for segmenting or selecting out-of-lab data for analysis. RESEARCH QUESTION: Do gait kinematics differ by bout duration or setting in young and older adults with and without knee osteoarthritis? METHODS: Ten young (28.1±3.5 yrs), ten older adults (60.8±3.3 yrs), and ten older adults with knee osteoarthritis (64.1±3.6 yrs) performed a standard in-lab gait analysis followed by a prescribed walking route outside the lab at a comfortable speed with four IMUs. Walking speed, stride length, and sagittal hip, knee, and ankle angular excursion (ROM) were calculated for each identified stride. Out-of-lab strides included straight-line, level walking divided into strides that occurred during long (>60 s) or short (≤60 s) bouts. Gait kinematics were compared between in-lab and both out-of-lab bout durations among groups. RESULTS: Significant main effects of setting or duration were found for walking speed and stride length, but there were no significant differences in hip, knee, or ankle joint ROM. Walking speed and stride length were greater in-lab followed by long and short bout out-of-lab. No significant interaction was observed between group and setting or bout duration for any spatiotemporal variables or joint ROMs. SIGNIFICANCE: Out-of-lab gait data can be beneficial in identifying gait characteristics that individuals may not encounter in the traditional lab setting. Setting has an impact on walking kinematics, so comparisons of in-lab and free-living gait may be impacted by the duration of walking bouts. A standardized approach for to analyzing out-of-lab gait data is important for comparing studies and populations.

A machine-learning approach for stress detection using wearable sensors in free-living environments.

Stress is a psychological condition resulting from the body's response to challenging situations, which can negatively impact physical and mental health if experienced over prolonged periods. Early detection of stress is crucial to prevent chronic health problems. Wearable sensors offer an effective solution for continuous and real-time stress monitoring due to their non-intrusive nature and ability to monitor vital signs, e.g., heart rate and activity. Typically, most existing research has focused on data collected in controlled environments. Yet, our study aims to propose a machine learning-based approach for detecting stress in a free-living environment using wearable sensors. We utilized the SWEET dataset, which includes data from 240 subjects collected via electrocardiography (ECG), skin temperature (ST), and skin conductance (SC). We assessed four machine learning models, i.e., K-Nearest Neighbors (KNN), Support Vector Classification (SVC), Decision Tree (DT), Random Forest (RF), and XGBoost (XGB) in four different settings. This study evaluates the performance of various machine learning models for stress classification using the SWEET dataset. The analysis included two binary classification scenarios (with and without SMOTE) and two multi-class classification scenarios (with and without SMOTE). The Random Forest model demonstrated superior performance in the binary classification without SMOTE, achieving an accuracy of 98.29 % and an F1-score of 97.89 %. For binary classification with SMOTE, the K-Nearest Neighbors model performed best, with an accuracy of 95.70 % and an F1-score of 95.70 %. In the three-level classification without SMOTE, the Random Forest model again excelled, achieving an accuracy of 97.98 % and an F1-score of 97.22 %. For three-level classification with SMOTE, XGBoost showed the highest performance, with an accuracy and F1-score of 98.98 %. These results highlight the effectiveness of different models under various conditions, emphasizing the importance of model selection and preprocessing techniques in enhancing classification performance.

Life cycle strategies in free-living unicellular eukaryotes: Diversity, evolution, and current molecular tools to unravel the private life of microorganisms.

An astonishing range of morphologies and life strategies has arisen across the vast diversity of protists, allowing them to thrive in most environments. In model protists, like Tetrahymena, Dictyostelium, or Trypanosoma, life cycles involving multiple life stages with different morphologies have been well characterized. In contrast, knowledge of the life cycles of free-living protists, which primarily consist of uncultivated environmental lineages, remains largely fragmentary. Various life stages and lineage-specific cellular innovations have been observed in the field for uncultivated protists, but such innovations generally lack functional characterization and have unknown physiological and ecological roles. In the actual state of knowledge, evidence of sexual processes is confirmed for 20% of free-living protist lineages. Nevertheless, at the onset of eukaryotic diversification, common molecular trends emerged to promote genetic recombination, establishing sex as an inherent feature of protists. Here, we review protist life cycles from the viewpoint of life cycle transitions and genetics across major eukaryotic lineages. We focus on the scarcely observed sexual cycle of free-living protists, summarizing evidence for its existence and describing key genes governing its progression, as well as, current methods for studying the genetics of sexual cycles in both cultivable and uncultivated protist groups.