Population isolation in the Plains spadefoot toad: causes and conservation implications
Range disjunctions appear to be common in nature, although they may be caused by various factors. They may simply be an artefact of inadequate sampling. If real, they may be the result of colonization events or habitat change. With natural habitats showing increasing fragmentation because of human activity, understanding the cause of a disjunction can have important conservation implications. We investigate the geographical range of the Plains spadefoot toad, Spea bombifrons, a widely distributed species in the midwestern and southwestern United States, with a putative disjunct population in southern Texas. We combine GIS mapping, species distribution modeling, and population genetic analysis to investigate this putative disjunction. We establish that this southern Texas population is truly geographically disjunct and genetically distinct. Further, using climate projections we show that this unique population is at high risk of local extinction.
Chunco et al. (2024) Population isolation in the Plains spadefoot toad: causes and conservation implications. PeerJ 12:e17968 https://doi.org/10.7717/peerj.17968
Application of a reaction-based water quality model to the total dissolved solids concentration of the Pasig River
With the goal to support effective water resource management, water quality models have gained popularity as tools for evaluating the distributions of pollutants and sediments. This work focuses on the application of the numerical solution of an advection-dispersion-reaction (ADR) water quality model for rivers and streams to a major Philippine waterway, the Pasig River. The water quality constituent is described by a system of reaction and advection-dispersion-reaction equations. The model and method are based on a previously used strategy where Guass-Jordan decomposition is applied to the matrix system and the resulting conservative form of the model is solved numerically using the fully implicit scheme and finite element method. The methodology is demonstrated by a case study in Pasig River involving the concentrations of total dissolved solids (TDS) obtained from the Department of Environment and Natural Resources (DENR) through the Pasig River Unified Monitoring Stations (PRUMS) report. Sensitivity analysis and parameter estimation are also applied to the model to assess which parameters influence the model output the most.
Environmental Contamination and Remediation
Abas et al. (2024) Application of a reaction-based water quality model to the total dissolved solids concentration of the Pasig River. PeerJ 12:e18076 https://doi.org/10.7717/peerj.18076
Genotype-specific responses to in vitro drought stress in myrtle (Myrtus communis L.): integrating machine learning techniques
Background Myrtle (Myrtus communis L.), native to the Mediterranean region of Türkiye, is a valuable plant with applications in traditional medicine, pharmaceuticals, and culinary practices. Understanding how myrtle responds to water stress is essential for sustainable cultivation as climate change exacerbates drought conditions. Methods This study investigated the performance of selected myrtle genotypes under in vitro drought stress by employing tissue culture techniques, rooting trials, and acclimatization processes. Genotypes were tested under varying polyethylene glycol (PEG) concentrations (1%, 2%, 4%, and 6%). Machine learning (ML) algorithms, including Gaussian process (GP), support vector machine (SVM), Random Forest (RF), and Extreme Gradient Boosting (XGBoost), were utilized to model and predict micropropagation and rooting efficiency. Results The research revealed a genotype-dependent response to drought stress. Black-fruited genotypes exhibited higher micropropagation rates compared to white-fruited ones under stress conditions. The application of ML models successfully predicted micropropagation and rooting efficiency, providing insights into genotype performance. Conclusions The findings suggest that selecting drought-tolerant genotypes is crucial for enhancing myrtle cultivation. The results underscore the importance of genotype selection and optimization of cultivation practices to address climate change impacts. Future research should explore the molecular mechanisms of stress responses to refine breeding strategies and improve resilience in myrtle and similar economically important crops.
Bektaş et al. (2024) Genotype-specific responses to in vitro drought stress in myrtle (Myrtus communis L.): integrating machine learning techniques. PeerJ 12:e18081 https://doi.org/10.7717/peerj.18081
Longitudinal relations between non-suicidal self-injury and both depression and anxiety among senior high school adolescents: a cross-lagged panel network analysis
Background Comorbidity between non-suicidal self-injury (NSSI) and depression and anxiety was common. In the framework of network theory, the examination of directionality and gender differences in longitudinal relationships at the symptom level made a significant contribution to the understanding of comorbidity. Therefore, this study employed cross-lagged panel network analysis to investigate the longitudinal interrelations between NSSI and depression and anxiety in Chinese adolescents, with a focus on gender differences. Method The study was conducted with a sample of 884 senior high school students (F/M: 481/403; mean age: 15.19 ± 0.48 years) from Jinchang City, Gansu Province, China. All respondents completed the Adolescent Non-Suicidal Self-Injury Assessment Questionnaire and the two subscales (depression and anxiety) of the Brief Symptom Inventory at two intervals. The data were estimated in R 4.2.0 to construct the cross-lagged panel network (CLPN). Results The CLPN results uncovered the gender differences. For boys, self-hitting and feeling scared emerged as central symptoms. Cutting predicted subsequent feelings of sadness (β = − 0.57), tension (β = − 0.52) and indifference (β = − 0.49), potentially serving as a bridge connecting NSSI to depression and anxiety. For girls, biting themselves and feeling scared were central symptoms. Carving and skin rubbing predicted subsequent feelings of indifference (β = − 0.31, −0.21), bridging NSSI to depression and anxiety. In addition, feeling scared emerged as the key bridge symptom connecting depression and anxiety. Conclusion The findings showed the gender-specific developmental characteristics of the directional relations between NSSI and depression and anxiety at the symptom level. They provided new insights into the comorbidity of NSSI and depression and anxiety, carrying important implications for the screening and intervention of adolescent NSSI.
Zhao et al. (2024) Longitudinal relations between non-suicidal self-injury and both depression and anxiety among senior high school adolescents: a cross-lagged panel network analysis. PeerJ 12:e18134 https://doi.org/10.7717/peerj.18134
Licorice-root extract and potassium sorbate spray improved the yield and fruit quality and decreased heat stress of the ‘osteen’ mango cultivar
Heat stress, low mango yields and inconsistent fruit quality are main challenges for growers. Recently, licorice-root extract (LRE) has been utilized to enhance vegetative growth, yield, and tolerance to abiotic stresses in fruit trees. Potassium sorbate (PS) also plays a significant role in various physiological and biochemical processes that are essential for mango growth, quality and abiotic stress tolerance. This work aimed to elucidate the effects of foliar sprays containing LRE and PS on the growth, yield, fruit quality, total chlorophyll content, and antioxidant enzymes of ‘Osteen’ mango trees. The mango trees were sprayed with LRE at 0, 2, 4 and 6 g/L and PS 0, 1, 2, and 3 mM. In mid-May, the mango trees were sprayed with a foliar solution, followed by monthly applications until 1 month before harvest. The results showed that trees with the highest concentration (6 g/L) of LRE exhibited the maximum leaf area, followed by those treated with the highest concentration (3 mM) of PS. Application of LRE and PS to Osteen mango trees significantly enhanced fruit weight, number of fruits per tree, yield (kg/tree), yield increasing%, and reduced number of sun-burned fruits compared to the control. LRE and PS foliar sprays to Osteen mango trees significantly enhanced fruit total soluble solids ˚Brix, TSS/acid ratio, and vitamin C content compared to the control. Meanwhile, total acidity percentage in ‘Osteen’ mango fruits significantly decreased after both LRE and PS foliar sprays. ‘Osteen’ mango trees showed a significant increase in leaf area, total chlorophyll content, total pigments, and leaf carotenoids. Our results suggest that foliar sprays containing LRE and PS significantly improved growth parameters, yield, fruit quality, antioxidant content, and total pigment concentration in ‘Osteen’ mango trees. Moreover, the most effective treatments were 3 mM PS and 6 g/L LRE. LRE and PS foliar spray caused a significant increase in yield percentage by 305.77%, and 232.44%, in the first season, and 242.55%, 232.44% in the second season, respectively.
Al-Saif et al. (2024) Licorice-root extract and potassium sorbate spray improved the yield and fruit quality and decreased heat stress of the ‘osteen’ mango cultivar. PeerJ 12:e18200 https://doi.org/10.7717/peerj.18200
A novel gene silencing strategy based on tobacco rattle virus in Hibiscus mutabilis
Background Hibiscus mutabilis L. is a popular regional characteristic plant in China, cultivated for its attractive flower colors, extended bloom time, and medicinal properties. To enhance molecular breeding and gene function studies, we conducted transcriptome analysis and identified valuable genes in previous research. Nonetheless, the current inefficient and labor-intensive transformation techniques have hindered their applications. Virus-induced gene silencing (VIGS) provides a precise and effective strategy for post-transcriptional down-regulation of endogenous gene expression. Methods We investigated the performance of tobacco rattle virus (TRV) as a tool for targeting and silencing the gene encoding the protein involved in chloroplast development, cloroplastos alterados 1 (altered chloroplast; CLA1), of H. mutabilis through Agrobacterium tumefaciens-mediated infiltration. Results By effectively suppressing the CLA1 gene associated with chloroplast development in H. mutabilis via the TRV-VIGS system, we have illustrated the inaugural implementation of VIGS in this species. Quantitative RT-PCR proved that HmCLA1 expression in agro-infiltrated plants was lower than in the mock-infiltrated (mock) and the control (CK) plants. Phenotypic observations corroborated the albino phenotype in leaves following successful HmCLA1 silencing. Conclusions Our study showcases TRV-VIGS as a potential gene silencing tool for H. mutabilis, facilitating functional genomics studies and molecular breeding efforts in this species.
Sang et al. (2024) A novel gene silencing strategy based on tobacco rattle virus in Hibiscus mutabilis. PeerJ 12:e18211 https://doi.org/10.7717/peerj.18211
Cross-cultural adaptation and psychometric properties of the Chinese version of the Intermittent Self-Catheterization Questionnaire (ISC-Q)
Background The intermittent self-catheterization questionnaire (ISC-Q) is a valid and reliable tool to assess the quality of life (QOL) in patients with neurogenic lower urinary tract dysfunction (NLUTD) who engage in ISC. The aim of this research is to culturally adapt the ISC-Q and evaluate its psychometric properties within the Chinese patient population. Methods The cross-sectional research was meticulously conducted in two pivotal stages: initially, the focus was on cross-cultural adaptation, followed by an extensive phase of psychometric testing. This comprehensive analysis involved 405 Chinese patients with NLUTD who use ISC. Various analyses, including evaluations of the floor and ceiling effects, item analysis, content validity, exploratory and confirmatory factor analysis (EFA and CFA), assessments of convergent, discriminant, and criterion validity. Additionally, Cronbach’s alpha was utilized to determine internal consistency, and test-retest reliability was measured using the intraclass correlation coefficient (ICC). Results No floor and ceiling effects were observed. The content validity index was 0.967. The EFA identified four factors, accounting for 64.953% of the total variance, and this four-factor structure was confirmed by the CFA. The fit indices in CFA were favorable, with χ2/df = 1.999, root mean square error of approximation = 0.070, comparative fit index = 0.916, Tucker–Lewis index = 0.900, goodness-of-fit index = 0.863, and incremental fit index = 0.917. The average variance extracted for the four factors ranged from 0.466 to 0.565, with composite reliability values ranging from 0.776 to 0.859. The ISC-Q showed a positive correlation with the intermittent self-catheterization acceptance questionnaire (r = 0.557, P < 0.001). The ICC overall Cronbach’s alpha coefficient for the questionnaire was 0.821, and the for test-retest reliability was 0.951 (95% CI [0.900–0.976] P < 0.001). Conclusion The validity and reliability of the Chinese version of the ISC-Q have been verified, making it suitable for measuring the QOL in NLUTD patients who practice ISC.
Hu et al. (2024) Cross-cultural adaptation and psychometric properties of the Chinese version of the Intermittent Self-Catheterization Questionnaire (ISC-Q). PeerJ 12:e18226 https://doi.org/10.7717/peerj.18226
Genome-wide association study reveals genetic basis and candidate genes for chlorophyll content of leaves in maize (Zea mays L.)
The chlorophyll content (CC) directly affects photosynthesis, growth, and yield. However, the genetic basis of CC is still unclear in maize (Zea mays L.). Here, we conducted a genome-wide association study using mixed linear model for CC of the fifth leaves at seedling stage (CCFSS) and the ear leaves at filling stage (CCEFS) for 334 maize inbred lines. The heritability estimates for CCFSS and CCEFS, obtained via variance components analysis using the lme4 package in R, were 70.84% and 78.99%, respectively, indicating that the CC of leaves is primarily controlled by genetic factors. A total of 15 CC-related SNPs and 177 candidate genes were identified with a p-value < 4.49 × 10−5, which explained 4.98–7.59% of the phenotypic variation. Lines with more favorable gene variants showed higher CC. Meanwhile, Gene Ontology (GO) analysis implied that these candidate genes were probably related to chlorophyll biosynthesis. In addition, gene-based association analyses revealed that six variants in GRMZM2G037152, GRMZM5G816561, GRMZM2G324462, and GRMZM2G064657 genes were significantly (p-value < 0.01) correlated with CC, of which GRMZM2G064657 (encodes a phosphate transporter protein) and GRMZM5G816561 (encodes a cytochrome P450 protein) were specifically highly expressed in leaves tissues. Interestingly, these candidate genes were previously reported to involve in the regulation of the contents of chlorophyll in plants or Chlamydomonas. These results may contribute to the understanding of genetic basis and molecular mechanisms of maize CC and the selection of maize varieties with improved CC.
Liu et al. (2024) Genome-wide association study reveals genetic basis and candidate genes for chlorophyll content of leaves in maize (Zea mays L.). PeerJ 12:e18278 https://doi.org/10.7717/peerj.18278
Changes in the force-time curve during a repeat power ability assessment using loaded countermovement jumps
Background Repeat power ability (RPA) assessments traditionally use discrete variables, such as peak power output, to quantify the change in performance across a series of jumps. Rather than using a discrete variable, the analysis of the entire force-time curve may provide additional insight into RPA performance. The aims of this study were to (1) analyse changes in the force-time curve recorded during an RPA assessment using statistical parametric mapping (SPM) and (2) compare the differences in the force-time curve between participants with low and high RPA scores, as quantified by traditional analysis. Materials and Methods Eleven well-trained field hockey players performed an RPA assessment consisting of 20 loaded countermovement jumps with a 30% one repetition maximum half squat load (LCMJ20). Mean force-time series data was normalized to 100% of the movement duration and analysed using SPM. Peak power output for each jump was also derived from the force-time data and a percent decrement score calculated for jumps 2 to 19 (RPA%dec). An SPM one-way ANOVA with significance accepted at α = 0.05, was used to identify the change in the force-time curve over three distinct series of jumps across the LCMJ20 (series 1 = jumps 2–5, series 2 = jumps 9–12 and series 3 = jumps 16–19). A secondary analysis, using an independent T-test with significance accepted at p < 0.001, was also used to identify differences in the force-time curve between participants with low and high RPA%dec. Results Propulsive forces were significantly lower (p < 0.001) between 74–98% of the movement compared to 0–73% for changes recorded during the LCMJ20. Post hoc analysis identified the greatest differences to occur between jump series 1 and jump series 2 (p < 0.001) at 70–98% of the movement and between jump series 1 and jump series 3 (p < 0.001) at 86–99% of the movement. No significant differences were found between jump series 2 and jump series 3. Significant differences (p < 0.001) in both the braking phase at 44–48% of the jump and the propulsive phase at 74–94% of the jump were identified when participants were classified based on low or high RPA%dec scores (with low scores representing an enhanced ability to maintain peak power output than high scores). Conclusion A reduction in force during the late propulsive phase is evident as the LCMJ20 progresses. SPM analysis provides refined insight into where changes in the force-time curve occur during performance of the LCMJ20. Participants with the lower RPA%dec scores displayed both larger braking and propulsive forces across the LCMJ20 assessment.
Natera et al. (2024) Changes in the force-time curve during a repeat power ability assessment using loaded countermovement jumps. PeerJ 12:e17971 https://doi.org/10.7717/peerj.17971
Acute psycho-physiological responses to submaximal constant-load cycling under intermittent hypoxia-hyperoxia vs. hypoxia-normoxia in young males
Background Hypoxia and hyperoxia can affect the acute psycho-physiological response to exercise. Recording various perceptual responses to exercise is of particular importance for investigating behavioral changes to physical activity, given that the perception of exercise-induced pain, discomfort or unpleasure, and a low level of exercise enjoyment are commonly associated with a low adherence to physical activity. Therefore, this study aimed to compare the acute perceptual and physiological responses to aerobic exercise under intermittent hypoxia-hyperoxia (IHHT), hypoxia-normoxia (IHT), and sustained normoxia (NOR) in young, recreational active, healthy males. Methods Using a randomized, single-blinded, crossover design, 15 males (age: 24.5 ± 4.2 yrs) performed 40 min of submaximal constant-load cycling (at 60% peak oxygen uptake, 80 rpm) under IHHT (5 × 4 min hypoxia and hyperoxia), IHT (5 × 4 min hypoxia and normoxia), and NOR. Inspiratory fraction of oxygen during hypoxia and hyperoxia was set to 14% and 30%, respectively. Heart rate (HR), total hemoglobin (tHb) and muscle oxygen saturation (SmO2) of the right vastus lateralis muscle were continuously recorded during cycling. Participants’ peripheral oxygen saturation (SpO2) and perceptual responses (i.e., perceived motor fatigue, effort perception, perceived physical strain, affective valence, arousal, motivation to exercise, and conflict to continue exercise) were surveyed prior, during (every 4 min), and after cycling. Prior to and after exercise, peripheral blood lactate concentration (BLC) was determined. Exercise enjoyment was ascertained after cycling. For statistical analysis, repeated measures analyses of variance were conducted. Results No differences in the acute perceptual responses were found between conditions (p ≥ 0.059, ηp2 ≤ 0.18), while the physiological responses differed. Accordingly, SpO2 was higher during the hyperoxic periods during the IHHT compared to the normoxic periods during the IHT (p < 0.001, ηp2 = 0.91). Moreover, HR (p = 0.005, ηp2 = 0.33) and BLC (p = 0.033, ηp2 = 0.28) were higher during IHT compared to NOR. No differences between conditions were found for changes in tHb (p = 0.684, ηp2 = 0.03) and SmO2 (p = 0.093, ηp2 = 0.16). Conclusion IHT was associated with a higher physiological response and metabolic stress, while IHHT did not lead to an increase in HR and BLC compared to NOR. In addition, compared to IHT, IHHT seems to improve reoxygenation indicated by a higher SpO2 during the hyperoxic periods. However, there were no differences in perceptual responses and ratings of exercise enjoyment between conditions. These results suggest that replacing normoxic by hyperoxic reoxygenation-periods during submaximal constant-load cycling under intermittent hypoxia reduced the exercise-related physiological stress but had no effect on perceptual responses and perceived exercise enjoyment in young recreational active healthy males.
Behrendt et al. (2024) Acute psycho-physiological responses to submaximal constant-load cycling under intermittent hypoxia-hyperoxia vs. hypoxia-normoxia in young males. PeerJ 12:e18027 https://doi.org/10.7717/peerj.18027