Arsenic and mercury tolerant rhizobacteria that can improve phytoremediation of heavy metal contaminated soils
Background Mining deposits often contain high levels of toxic elements such as mercury (Hg) and arsenic (As) representing strong environmental hazards. The purpose of this study was the isolation for plant growth promoting bacteria (PGPBs) that can improve phytoremediation of such mine waste deposits. Methods We isolated native soil bacteria from the rhizosphere of plants of mine waste deposits and agricultural land that was previously mine tailings from Tlalpujahua Michoacán, Mexico, and were identified by their fatty acid profile according to the MIDI Sherlock system. Plant growth promoting traits of all bacterial isolates were examined including production of 3-indoleacetic acid (IAA), siderophores, biofilm formation, and phosphate solubilization. Finally, the response of selected bacteria to mercury and arsenic was examined an in-vitro assay. Results A total 99 bacterial strains were isolated and 48 identified, representing 34 species belonging to 23 genera. Sixty six percent of the isolates produced IAA of which Pseudomonas fluorescens TL97 produced the most. Herbaspirillum huttiense TL36 performed best in terms of phosphate solubilization and production of siderophores. In terms of biofilm formation, Bacillus atrophaeus TL76 was the best. Discussion Most of the bacteria isolates showed high level of tolerance to the arsenic (as HAsNa2O4 and AsNaO2), whereas most isolates were susceptible to HgCl2. Three of the selected bacteria with PGP traits Herbispirillum huttiense TL36, Klebsiella oxytoca TL49 and Rhizobium radiobacter TL52 were also tolerant to high concentrations of mercury chloride, this might could be used for restoring or phytoremediating the adverse environmental conditions present in mine waste deposits.
Environmental Contamination and Remediation
Rojas-Solis et al. (2023) Arsenic and mercury tolerant rhizobacteria that can improve phytoremediation of heavy metal contaminated soils. PeerJ 11:e14697 https://doi.org/10.7717/peerj.14697
Effects of high-intensity interval exercise on cardiac troponin elevation when comparing with moderate-intensity continuous exercise: a systematic review and meta-analysis
Background This systematic review and meta-analysis aimed to compare the effects of high-intensity interval exercise (HIIE) with different recovery modes versus moderate-intensity continuous exercise (MICE) on cardiac troponin (cTn) elevation. Methodology A literature search was conducted in four databases: Scopus, PubMed, EBSCO and Web of Science from January 2010 to June 2022. The articles were screened, evaluated for quality before data were extracted. The review protocol was registered at PROSPERO (CRD42021245649). Standardized mean differences (SMD) of peak cTn were analyzed with a 95% confidence interval (95% CI) using Revman 5.4 software. Results Six studies satisfied the inclusion criteria with a total of 92 and 79 participants for HIIE and MICE, respectively. Overall, there was no significant difference between HIIE and MICE in the elevation of cardiac troponin T (SMD: 0.41 [95% CI [−0.21, 1.03]], p = 0.20, I2 = 77%, p for heterogeneity <0.01). In subgroup analysis, HIIE with passive recovery elicits greater release of cardiac troponin T than MICE (SMD: 0.85 [95% CI [0.44, 1.27]], p < 0.01, I2 = 32%, p for heterogeneity = 0.22). Changes of cardiac troponin T (SMD: 0.41 [95% CI [−0.21, 1.03]], p = 0.20, I2 = 77%, p for heterogeneity < 0.01) after HIIE with active recovery were not significantly different from those of MICE. Conclusions There was no significant difference between HIIE and MICE in the elevation of cardiac troponin T. However, HIIE with passive recovery elicited more cardiac troponin T elevation than MICE, which should be considered when developing exercise programs.
Li et al. (2023) Effects of high-intensity interval exercise on cardiac troponin elevation when comparing with moderate-intensity continuous exercise: a systematic review and meta-analysis. PeerJ 11:e14508 https://doi.org/10.7717/peerj.14508
Taxonomic review of Saguinus mystax (Spix, 1823) (Primates, Callitrichidae), and description of a new species
Although the Amazon has the greatest diversity of primates, there are still taxonomic uncertainties for many taxa, such as the species of the Saguinus mystax group. The most geographically broadly distributed and phenotypically diverse species in this group is S. mystax, and its phenotypic diversity has been recognized as three subspecies—S. mystax mystax, S. mystax pileatus and S. mystax pluto—with non-overlapping geographic distributions. In this sense, we carried out an extensive field survey in their distribution areas and used a framework of taxonomic hypothesis testing of genomic data combined with an integrative taxonomic decision-making framework to carry out a taxonomic revision of S. mystax. Our tests supported the existence of three lineages/species. The first species corresponds to Saguinus mystax mystax from the left bank of the Juruá River, which was raised to the species level, and we also discovered and described animals from the Juruá–Tefé interfluve previously attributed to S. mystax mystax as a new species. The subspecies S. m. pileatus and S. m. pluto are recognized as a single species, under a new nomenclatural combination. However, given their phenotypic distinction and allopatric distribution, they potentially are a manifestation of an early stage of speciation, and therefore we maintain their subspecific designations.
Lopes et al. (2023) Taxonomic review of Saguinus mystax (Spix, 1823) (Primates, Callitrichidae), and description of a new species. PeerJ 11:e14526 https://doi.org/10.7717/peerj.14526
Senile dementia and psychiatric stigma among community health service providers and relatives of diagnosed and suspected dementia patients: a cross-sectional study
Background The number of people suffering from dementia is increasing rapidly in China. Early identification, referral, and intervention for dementia patients within communities are important to public health. However, these measures could be impacted by misconceptions about dementia and associated psychiatric stigma from community health professionals and relatives of dementia patients. Methods A cross-sectional survey was conducted on 249 participants, which included community doctors, community nurses, and relatives of diagnosed and suspected dementia patients in Guiyang, China. Participants were recruited through convenient sampling. The Chinese version of Dementia Knowledge Assessment Scale (DKAS) and the Perceived Psychiatric Stigma Scale (PPSS) were used to evaluate the participants’ knowledge of dementia and dementia-related psychiatric stigma. Results A total of 249 participants completed the questionnaire. The participants had moderate overall knowledge of dementia and the associated psychiatric stigma. Participants who were ≥45 years old, had a low level of education, had a low monthly income, or gained knowledge of dementia through non-media channels had lower awareness of dementia and stronger psychiatric stigma. In the “Communication & behavior” subscale of DKAS, all participants had a low level of awareness. Relatives of diagnosed and suspected dementia patients had higher total PPSS and “Marital preclusion” subscale scores than community doctors and nurses but lower psychiatric stigma based on the PPSS “Self-deprecation” subscale score. Conclusions Despite their profession, community doctors and nurses did not show an absolute advantage over relatives of diagnosed and suspected dementia patients in the dementia knowledge, and they even showed higher psychiatric stigma in some subscales. The self-deprecation subscale is related to the identification with negative labels such as “people with a mental illness are the weak”. This study shows that reducing stigma on the “Self-deprecation” subscale should be a core component of training and educational programs targeted at improving dementia knowledge among community health service providers.
Zhang et al. (2023) Senile dementia and psychiatric stigma among community health service providers and relatives of diagnosed and suspected dementia patients: a cross-sectional study. PeerJ 11:e14613 https://doi.org/10.7717/peerj.14613
Anatomical and physiological responses of Aechmea blanchetiana (Bromeliaceae) induced by silicon and sodium chloride stress during in vitro culture
Salt stress is one of the most severe abiotic stresses affecting plant growth and development. The application of silicon (Si) is an alternative that can increase the tolerance of plants to various types of biotic and abiotic stresses. The objective was to evaluate salt stress’s effect in vitro and Si’s mitigation potential on Aechmea blanchetiana plants. For this purpose, plants already established in vitro were transferred to a culture medium with 0 or 14 µM of Si (CaSiO3). After growth for 30 days, a stationary liquid medium containing different concentrations of NaCl (0, 100, 200, or 300 µM) was added to the flasks. Anatomical and physiological analyses were performed after growth for 45 days. The plants cultivated with excess NaCl presented reduced root diameter and effective photochemical quantum yield of photosystem II (PSII) (ΦPSII) and increased non-photochemical dissipation of fluorescence (qN). Plants that grew with the presence of Si also had greater content of photosynthetic pigments and activity of the enzymes of the antioxidant system, as well as higher values of maximum quantum yield of PSII (FV/FM), photochemical dissipation coefficient of fluorescence (qP) and fresh weight bioaccumulation of roots and shoots. The anatomical, physiological and biochemical responses, and growth induced by Si mitigated the effect of salt stress on the A. blanchetiana plants cultivated in vitro, which can be partly explained by the tolerance of this species to grow in sandbank (Restinga) areas.
Cipriano et al. (2023) Anatomical and physiological responses of Aechmea blanchetiana (Bromeliaceae) induced by silicon and sodium chloride stress during in vitro culture. PeerJ 11:e14624 https://doi.org/10.7717/peerj.14624
Mass media pressure on physical build, psychological well-being and physical-healthy profile. An explanatory model in adulthood
Background The pressure exerted by the media on mental image, psychological well-being and the physical-dietary sphere is of vital interest in understanding human behavioral patterns at different stages of development. The present research reflects the objectives of developing an explanatory model of the associations between media pressure and physical build on psychological well-being, physical activity and the Mediterranean diet and testing the structural model using a multi-group model according to participants’ stage of adulthood development. Methods A descriptive, non-experimental, cross-sectional study was carried out on a sample of 634 participants aged between 18 and 65 years (35.18 ± 9.68). An ad hoc socio-demographic questionnaire, Sociocultural Attitudes Towards Appearance Questtionnaire-4, Psychological Well-Being Scale, Predimed questtionnaire and International Physical Activity Questionnaire-Short Form were used for data collection. Results Participants in early adulthood show higher scores for media pressure and for pressure on physical build. It is also observed that participants in middle adulthood show higher scores for psychological well-being and physical activity levels. Conclusions In conclusion, it can be seen that there are a large number of physical, physical-health and psychological differences in each of the phases of adulthood.
Melguizo-Ibáñez et al. (2023) Mass media pressure on physical build, psychological well-being and physical-healthy profile. An explanatory model in adulthood. PeerJ 11:e14652 https://doi.org/10.7717/peerj.14652
Transcriptome and metabolome response of eggplant against Ralstonia solanacearum infection
Bacterial wilt is a soil-borne disease that represents ubiquitous threat to Solanaceae crops. The whole-root transcriptomes and metabolomes of bacterial wilt-resistant eggplant were studied to understand the response of eggplant to bacterial wilt. A total of 2,896 differentially expressed genes and 63 differences in metabolites were identified after inoculation with Ralstonia solanacearum. Further analysis showed that the biosynthesis pathways for phytohormones, phenylpropanoids, and flavonoids were altered in eggplant after inoculation with R. solanacearum. The results of metabolomes also showed that phytohormones played a key role in eggplant response to bacterial wilt. Integrated analyses of the transcriptomic and metabolic datasets indicated that jasmonic acid (JA) content and gene involved in the JA signaling pathway increased in response to bacterial wilt. These findings remarkably improve our understanding of the mechanisms of induced defense response in eggplant and will provide insights intothe development of disease-resistant varieties of eggplant.
Xiao et al. (2023) Transcriptome and metabolome response of eggplant against Ralstonia solanacearum infection. PeerJ 11:e14658 https://doi.org/10.7717/peerj.14658
Distribution, conservation status and proposed measures for preservation of Radiodiscus microgastropods in Chile
The genus Radiodiscus includes minute terrestrial snails occurring throughout the American continent. We assessed the conservation status of eight poorly known Chilean Radiodiscus species using the International Union for Conservation of Nature (IUCN) and NatureServe categories and criteria. Under the IUCN guidelines the species were assessed using the Criterion B of geographic range, which considers the extent of occurrence (EOO) and area of occupancy (AOO) as subcriteria. For NatureServe we used these two parameters plus the number of occurrences, ecological viability, and threats. Considering species rarity and possible sampling bias, we also used ecological niche modeling to determine climate and environmental tolerances and predict potential species distributions analyzing bioclimatic and geographical layers. Radiodiscus australis, R. coarctatus and R. quillajicola were listed as Critically Endangered by IUCN and NatureServe standards; R. coppingeri, R. flammulatus, R. magellanicus and R. villarricensis as Endangered by both methods; while R. riochicoensis as Endangered by IUCN standards and Vulnerable by NatureServe standards. Niche modeling results indicated that Radiodiscus species respond to different environmental conditions and that the predicted distribution areas contain suitable habitats beyond the current ranges, which may be helpful for future management plans. Nature-based sport tourism, forestry activities, urbanization, roads, pollution, mining, forest fires, livestock, volcanism, tsunamis, soil erosion and introduced species are among the major threats affecting these snails. Based on the low number of occurrences and the threats identified, the most at-risk species are R. coarctatus and R. quillajicola (one record), R. australis (two records) and R. villarricensis (three records); the latter two lacking occurrences within protected areas. Compiling our findings, we propose a list of actions to preserve Chilean Radiodiscus species.
Collado et al. (2023) Distribution, conservation status and proposed measures for preservation of Radiodiscus microgastropods in Chile. PeerJ 11:e14027 https://doi.org/10.7717/peerj.14027
RNA-Seq and genetic diversity analysis of faba bean (Vicia faba L.) varieties in China
Background Faba bean (Vicia faba L) is one of the most important legumes in the world. However, there is relatively little genomic information available for this species owing to its large genome. The lack of data impedes the discovery of molecular markers and subsequent genetic research in faba bean. The objective of this study was to analyze the faba bean transcriptome, and to develop simple sequence repeat (SSR) markers to determine the genetic diversity of 226 faba bean varieties derived from different regions in China. Methods Faba bean varieties with different phenotype were used in transcriptome analysis. The functions of the unigenes were analyzed using various database. SSR markers were developed and the polymorphic markers were selected to conduct genetic diversity analysis. Results A total of 92.43 Gb of sequencing data was obtained in this study, and 133,487 unigene sequences with a total length of 178,152,541 bp were assembled. A total of 5,200 SSR markers were developed on the basis of RNA-Seq analysis. Then, 200 SSR markers were used to evaluate polymorphisms. In total, 103 (51.5%) SSR markers showed significant and repeatable bands between different faba bean varieties. Clustering analysis revealed that 226 faba bean materials were divided into five groups. Genetic diversity analysis revealed that the relationship between different faba beans in China was related, especially in the same region. These results provided a valuable data resource for annotating genes to different categories and developing SSR markers.
Hou et al. (2023) RNA-Seq and genetic diversity analysis of faba bean (Vicia faba L.) varieties in China. PeerJ 11:e14259 https://doi.org/10.7717/peerj.14259
Flexor hallucis brevis motor unit behavior in response to moderate increases in rate of force development
Background Studies on motor unit behaviour with varying rates of force development have focussed predominantly on comparisons between slow and ballistic (i.e., very fast) contractions. It remains unclear how motor units respond to less extreme changes in rates of force development. Here, we studied a small intrinsic foot muscle, flexor hallucis brevis (FHB) where the aim was to compare motor unit discharge rates and recruitment thresholds at two rates of force development. We specifically chose to investigate relatively slow to moderate rates of force development, not ballistic, as the chosen rates are more akin to those that presumably occur during daily activity. Methods We decomposed electromyographic signals to identify motor unit action potentials obtained from indwelling fine-wire electrodes in FHB, from ten male participants. Participants performed isometric ramp-and-hold contractions from relaxed to 50% of a maximal voluntary contraction. This was done for two rates of force development; one with the ramp performed over 5 s (slow condition) and one over 2.5 s (fast condition). Recruitment thresholds and discharge rates were calculated over the ascending limb of the ramp and compared between the two ramp conditions for matched motor units. A repeated measures nested linear mixed model was used to compare these parameters statistically. A linear repeated measures correlation was used to assess any relationship between changes in recruitment threshold and mean discharge rate between the two conditions. Results A significant increase in the initial discharge rate (i.e., at recruitment) in the fast (mean: 8.6 ± 2.4 Hz) compared to the slow (mean: 7.8 ± 2.3 Hz) condition (P = 0.027), with no changes in recruitment threshold (P = 0.588), mean discharge rate (P = 0.549) or final discharge rate (P = 0.763) was observed. However, we found substantial variability in motor unit responses within and between conditions. A small but significant negative correlation (R2 = 0.33, P = 0.003) was found between the difference in recruitment threshold and the difference in mean discharge rate between the two conditions. Conclusion These findings suggest that as force increases for contractions with slower force development, increasing the initial discharge rate of recruited motor units produces the increase in rate of force development, without a change in their recruitment thresholds, mean or final discharge rate. However, an important finding was that for only moderate changes in rate of force development, as studied here, not all units respond similarly. This is different from what has been described in the literature for ballistic contractions in other muscle groups, where all motor units respond similarly to the increase in neural drive. Changing the discharge behaviour of a small group of motor units may be sufficient in developing force at the required rate rather than having the discharge behaviour of the entire motor unit pool change equally.
Aeles et al. (2023) Flexor hallucis brevis motor unit behavior in response to moderate increases in rate of force development. PeerJ 11:e14341 https://doi.org/10.7717/peerj.14341