title: PeerJ description: Articles published in PeerJ link: https://peerj.com/articles/index.rss3?journal=peerj&page=696 creator: info@peerj.com PeerJ errorsTo: info@peerj.com PeerJ language: en title: Calotropin and corotoxigenin 3-O-glucopyranoside from the desert milkweed Asclepias subulata inhibit the Na+/K+-ATPase activity link: https://peerj.com/articles/13524 last-modified: 2022-06-02 description: Na+/K+-ATPase is an essential transmembrane enzyme found in all mammalian cells with critical functions for cell ion homeostasis. The inhibition of this enzyme by several cardiotonic steroids (CTS) has been associated with the cytotoxic effect on cancer cell lines of phytochemicals such as ouabain and digitoxin. This study evaluated the inhibitory capacity of cardenolides calotropin and corotoxigenin 3-O-glucopyranoside (C3OG) from Asclepias subulata over the Na+/K+-ATPase activity in vitro and silico. The inhibitory assays showed that calotropin and C3OG decreased the Na+/K+-ATPase activity with IC50 values of 0.27 and 0.87 μM, respectively. Furthermore, the molecules presented an uncompetitive inhibition on Na+/K+-ATPase activity, with Ki values of 0.2 μM to calotropin and 0.5 μM to C3OG. Furthermore, the molecular modeling indicated that calotropin and C3OG might interact with the Thr797 and Gln111 residues, considered essential to the interaction with the Na+/K+-ATPase. Besides, these cardenolides can interact with amino acid residues such as Phe783, Leu125, and Ala323, to establish hydrophobic interactions on the binding site. Considering the results, these provide novel evidence about the mechanism of action of cardenolides from A. subulata, proposing that C3OG is a novel cardenolide that deserves further consideration for in vitro cellular antiproliferative assays and in vivo studies as an anticancer molecule. creator: Salvador E. Meneses-Sagrero creator: Luisa A. Rascón-Valenzuela creator: Juan C. García-Ramos creator: Wagner Vilegas creator: Aldo A. Arvizu-Flores creator: Rogerio R. Sotelo-Mundo creator: Ramon E. Robles-Zepeda uri: https://doi.org/10.7717/peerj.13524 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Meneses-Sagrero et al. title: High-throughput sequencing reveals rhizosphere fungal community composition and diversity at different growth stages of Populus euphratica in the lower reaches of the Tarim River link: https://peerj.com/articles/13552 last-modified: 2022-06-02 description: BackgroundPopulus euphratica is one of the most ancient and primitive tree species of Populus spp and plays an important role in maintaining the ecological balance in desert areas. To decipher the diversity, community structure, and relationship between rhizosphere fungi and environmental factors at different growth stages of P. euphratica demands an in-depth investigation.MethodsIn this study, P. euphratica at different growth stages (young, medium, overripe, and decline periods) was selected as the research object, based on the determination of the physicochemical properties of its rhizosphere soil, the fungal community structure and diversity of P. euphratica and their correlation with soil physicochemical properties were comprehensively analyzed through high-throughput sequencing technology (internal transcribed spacer (ITS)) and bioinformatics analysis methods.ResultsAccording to the analysis of OTU annotation results, the rhizosphere soil fungal communities identified in Populus euphratica were categorized into10 phyla, 36 classes, 77 orders, 165 families, 275 genera and 353 species. The alpha diversity analysis showed that there was no obvious change between the different growth stages, while beta diversity analysis showed that there were significantly differences in the composition of rhizosphere soil fungal communities between mature and overripe trees (R2 = 0.31, P = 0.001), mature and deadwood (R2 = 0.28, P = 0.001). Ascomycota and Basidiomycota were dominant phyla in the rhizosphere fungal community and the dominant genera were Geopora, Chondrostereum and unidentified_Sordariales_sp. The relative abundance of the top ten fungi at each classification level differed greatly in different stages. Canonical correspondence analysis (CCA) and Spearman’s correlation analysis showed that conductivity (EC) was the main soil factor affecting the composition of Populus euphratica rhizosphere soil fungal community (P < 0.01), followed by total dissolvable salts (TDS) and available potassium (AK) (P < 0.05).ConclusionsOur data revealed that the rhizosphere fungal communities at the different growth stages of P. euphratica have differences, conductivity (EC) was the key factor driving rhizosphere fungi diversity and community structure, followed by total dissolvable salts (TDS) and available potassium (AK). creator: Yuanyuan Li creator: Hanli Dang creator: Xinhua Lv creator: Zhongke Wang creator: Xiaozhen Pu creator: Li Zhuang uri: https://doi.org/10.7717/peerj.13552 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Li et al. title: Nitric oxide production rather than oxidative stress and cell death is associated with the onset of coral bleaching in Pocillopora acuta link: https://peerj.com/articles/13321 last-modified: 2022-06-01 description: Elevated seawater temperatures associated with climate change lead to coral bleaching. While the ultimate causes of bleaching are well understood, the proximate physiological mechanisms underlying the bleaching response are not as well defined. Here we measured nitric oxide synthase activity, oxidative stress, and cell death in algal symbionts (Symbiodinaceae) freshly isolated from the reef-building coral Pocillopora acuta collected in the field under natural non-bleaching conditions and from corals experimentally exposed to elevated temperatures. Nitric oxide synthase activity in the algal symbionts was >3 orders of magnitude higher than that of the host and increased dramatically with increasing temperature and time of exposure (up to 72 h), consistent with the onset of bleaching for these corals. Oxidative stress and cell death among the algal symbionts were highest in coral holobionts exposed to intermediate as opposed to maximal temperatures, suggesting that these mechanisms are not proximal triggers for bleaching in this species. Our results point to nitric oxide production by the algal symbionts, rather than symbiont dysfunction, as a more important driver of coral bleaching under acute thermal stress in this coral. creator: Christopher P. Jury creator: Brian M. Boeing creator: Henry Trapido-Rosenthal creator: Ruth D. Gates creator: Robert J. Toonen uri: https://doi.org/10.7717/peerj.13321 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Jury et al. title: Assessment of a developed pig cadaver model for teaching crown lengthening surgical procedures link: https://peerj.com/articles/13421 last-modified: 2022-06-01 description: BackgroundInformation regarding using a pig cadaver model for teaching purposes in dentistry is limited, especially for periodontal surgery procedures. The aim of this study was to assess the feasibility and efficacy of teaching crown lengthening surgical procedures using a prepared pig cadaver model.MethodsMandibles of slaughtered pigs with subgingival crown fracture defects on two premolars and two molars on each side were prepared as periodontal surgery teaching cases. A resident group (n = 20) and an instructor group (n = 18) participated in assessing the efficacy of the model by completing questionnaires before and after training sessions. Data was either assessed descriptively or analyzed statistically with Wilcoxon signed-rank test with the significance level at α = 0.05.ResultsResults revealed that all the knowledge points showed statistically significant improvements (p < 0.05) except for the procedure to determine the quantity of bone removal during osteotomy procedures. Most residents rated the efficacy of the model obtained with 9.0 out of 10 scale. The data of effectiveness of the pig cadaver model from the instructor group ranged from 7.4 ± 1.4 to 9.0 ± 1.0.ConclusionResults of this study support feasibility in using prepared pig cadaver models to teach crown lengthening surgical procedures to postgraduates. creator: Jinsheng Zhong creator: Dong Shi creator: Cui Wang creator: Min Zhen creator: Yiping Wei creator: Ziyao Han creator: Wenjie Hu creator: Kwok-Hung Chung uri: https://doi.org/10.7717/peerj.13421 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Zhong et al. title: First genomic resource for an endangered neotropical mega-herbivore: the complete mitochondrial genome of the forest-dweller (Baird’s) tapir (Tapirus bairdii) link: https://peerj.com/articles/13440 last-modified: 2022-06-01 description: Baird’s tapir, or the Central American Tapir Tapirus bairdii (family Tapiridae), is one of the largest mammals native to the forests and wetlands of southern North America and Central America, and is categorized as ‘endangered’ on the 2014 IUCN Red List of Threatened Species. This study reports, for the first time, the complete mitochondrial genome of T. bairdii and examines the phylogenetic position of T. bairdii amongst closely related species in the same family and order to which it belongs using mitochondrial protein-coding genes (PCG’s). The circular, double-stranded, A-T rich mitochondrial genome of T. bairdii is 16,697 bp in length consisting of 13 protein-coding genes (PCG’s), two ribosomal RNA genes (rrnS (12s ribosomal RNA and rrnL (16s ribosomal RNA)), and 22 transfer RNA (tRNA) genes. A 33 bp long region was identified to be the origin of replication for the light strand (OL), and a 1,247 bp long control region (CR) contains the origin of replication for the heavy strand (OH). A majority of the PCG’s and tRNA genes are encoded on the positive, or heavy, strand. The gene order in T. baiirdi is identical to that of T. indicus and T. terrestris, the only two other species of extant tapirs with assembled mitochondrial genomes. An analysis of Ka/Ks ratios for all the PCG’s show values <1, suggesting that all these PCGs experience strong purifying selection. A maximum-likelihood phylogenetic analysis supports the monophyly of the genus Tapirus and the order Perissodactyla. The complete annotation and analysis of the mitochondrial genome of T. bairdii will contribute to a better understanding of the population genomic diversity and structure of this species, and it will assist in the conservation and protection of its dwindling populations. creator: Caroline C. Ennis creator: Jorge Ortega creator: J. Antonio Baeza uri: https://doi.org/10.7717/peerj.13440 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Ennis et al. title: Grafting-enhanced tolerance of cucumber to toxic stress is associated with regulation of phenolic and other aromatic acids metabolism link: https://peerj.com/articles/13521 last-modified: 2022-06-01 description: Toxic stress caused by autotoxins is a common phenomenon for cucumber under monoculture condition. A previous study demonstrated that grafting could enhance the resistance of cucumber to cinnamic acid (CA) stress, but the underlying mechanism behind this enhanced resistance is still unclear. In the present study, we reconfirmed the stronger resistance of grafted rootstock (RG) compared to the non-grafted (NG) cucumber as measured though plant biomass accumulation. In addition, we focused on the phenolic and other aromatic acids metabolism in hydroponic culture model system using a combination of qRT-PCR (to measure gene expression of relevant genes) and HPLC (to detect the presence of phenolic and other aromatic acids). The results showed that the exogenous CA lead to the expression of four enzymes involved in phenolic and other aromatic acids biosynthesis, and a larger increase was observed in grafted rootstock (RG). Specifically, expression of six genes, involved in phenolic and other aromatic acids biosynthesis (PAL, PAL1, C4H, 4CL1, 4CL2 and COMT), with the exception of 4CL2, were significantly up-regulated in RG but down-regulated in NG when exposed to CA. Furthermore, six kinds of phenolic and other aromatic acids were detected in leaves and roots of NG and RG cucumber, while only benzoic acid and cinnamic acid were detected in root exudate of all samples. The CA treatment resulted in an increase of p-hydroxybenzonic acid, benzoic acid and cinnamic acid contents in RG cucumber, but decrease of p-coumaric acid and sinapic acid contents in NG cucumber. Surprisingly, the type and amount of phenolic and other aromatic acids in root exudate was improved by exogenous CA, particularly for RG cucumber. These results suggest that a possible mechanism for the stronger resistance to CA of RG than NG cucumber could involve the up-regulation of key genes involved in phenolic and other aromatic acids metabolism, and that the excessive phenolic compounds released to surroundings is a result of the accumulation of phenolic compounds in a short time by the plant under stress. creator: Xuemei Xiao creator: Ju Li creator: Jian Lyu creator: Linli Hu creator: Yue Wu creator: Zhongqi Tang creator: Jihua Yu creator: Alejandro Calderón-Urrea uri: https://doi.org/10.7717/peerj.13521 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Xiao et al. title: Study on soil-water characteristic curves in the profiles of collapsing walls of typical granite Benggang in southeast China link: https://peerj.com/articles/13526 last-modified: 2022-06-01 description: Benggang with steep collapsing walls is one of the worst soil erosion problems in South China. The collapse of walls is the most critical process in Benggang development. This is mainly due to the soil water properties. The soil water characteristic curve (SWCC) is a key indicator for analyzing soil moisture, but the SWCC and its mechanism of influence in collapsing walls remain obscure. A pressure plate meter was used for drying experiments to research the SWCCs of undisturbed soils of five layers (from top to bottom: red soil layer, transition layer I, sand soil layer, transition layer II and detrital layer) of two typical collapsing walls. The van Genuchten (VG) model can be fitted to the SWCCs for different layers (NSE ≥ 0.90). With increasing soil depth, the parameters a and θs first decreased and then increased, the parameters n first increased and then decreased, θr declined as the soil depth increased. These findings illustrate that soil water holding capacity decreases with increasing soil depth. The bottom of the soil is weak in water retention and water can easily reach saturation, resulting in a decline in soil stability, thus promoting soil collapse and finally inducing upper soil collapse. Furthermore, gravel content and particle morphology are factors that should not be neglected for SWCCs. The results of this study provide a theoretical basis for understanding the process of wall collapse in Benggang landforms in South China. creator: Liting Zhang creator: Shujun Sun creator: Mengqi Lin creator: Kaijun Feng creator: Yue Zhang creator: Jinshi Lin creator: Hongli Ge creator: Yanhe Huang creator: Fangshi Jiang uri: https://doi.org/10.7717/peerj.13526 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Zhang et al. title: The effect of listening to preferred music after a stressful task on performance and psychophysiological responses in collegiate golfers link: https://peerj.com/articles/13557 last-modified: 2022-06-01 description: BackgroundThis study explores whether listening to preferred music after a stressful situation affects putting and swinging performance, heart rate (HR), HR variability (HRV), and anxiety among amateur golfers.MethodsTwenty healthy amateur collegiate golfers voluntarily participated in this study (age 20.1 ± 1.17 yrs., height = 173.8 ± 7.74 cm, body weight = 72.35 ± 12.67 kg). Pre- and post-intervention HR and HRV measurements were taken, along with a self-report of the State-Trait Anxiety Inventory (STAI-S) and Triple Factor Anxiety Inventory (TFAI). Participants were exposed to a stressful situation through the Stroop Colour and Word Test (SCWT) and then instructed to perform three golf-practice sessions in a golf simulator, separated by 48–72 hours of recovery, under different conditions: control, pre-task music, and synchronised music.ResultsNo significant difference was identified between the experimental conditions for swinging (in terms of total distance (p = 0.116), carry distance (p = 0.608), speed of the ball (p = 0.819), and launch angle (p = 0.550) and putting performance (the number of successful putts on target (p > 0.05) and distance error between the target and ball (p = 0.122). No main effect for condition and time of intervention, as well as no interaction between these two factors was found for HR, HRV, and STAI-S (p = 0.116). However, the pre and post-intervention percentages of physiological items of the TFAI indicated a large, significant difference in synchronised music trial (p = 0.012, pre-task trial = −1.92% < control trial = 0% < synchronised trial = 4.58%).ConclusionsThe results imply that following a stressful situation, listening to preferred music before and/or during golf has no immediate effect on golf performance, anxiety, and psychophysiological responses in collegiate golfers. creator: Hung-Tsung Wang creator: Yung-Sheng Chen creator: Ghazi Rekik creator: Chia-Chen Yang creator: Mao-Sheng Lai creator: Hsia-Ling Tai uri: https://doi.org/10.7717/peerj.13557 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Wang et al. title: High gene flow in the silverlip pearl oyster Pinctada maxima between inshore and offshore sites near Eighty Mile Beach in Western Australia link: https://peerj.com/articles/13323 last-modified: 2022-05-31 description: An understanding of stock recruitment dynamics in fisheries is fundamental to successful management. Pinctada maxima is a bivalve mollusc widely distributed throughout the Indo-Pacific and is the main species targeted for cultured pearl and pearl shell production in Australia. Pearl production in Australia relies heavily on wild-caught individuals, the majority of which come from the Eighty Mile Beach region near Broome in Western Australia. In this study, we used a genotyping by sequencing approach to explore fine-scale patterns of genetic connectivity among inshore shallow and offshore deep populations of P. maxima near Eighty Mile Beach. Our results revealed high-levels of gene flow among inshore and offshore sites and no differences in genetic diversity between depths. Global estimates of genetic differentiation were low (FST = 0.006) but significantly different from zero, and pairwise estimates of genetic differentiation among sites were significant in only 3% of comparisons. Moreover, Bayesian clustering detected no separation of inshore and offshore sample sites, and instead showed all samples to be admixed among sites, locations and depths. Despite an absence of any clear spatial clustering among sites, we identified a significant pattern of isolation by distance. In a dynamic environment like Eighty Mile Beach, genetic structure can change from year-to-year and successive dispersal and recruitment events over generations likely act to homogenize the population. Although we cannot rule out the null hypothesis of panmixia, our data indicate high levels of dispersal and connectivity among inshore and offshore fishing grounds. creator: Luke Thomas creator: Karen J. Miller uri: https://doi.org/10.7717/peerj.13323 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Thomas and Miller title: Ferulic acid attenuates high glucose-induced apoptosis in retinal pigment epithelium cells and protects retina in db/db mice link: https://peerj.com/articles/13375 last-modified: 2022-05-31 description: BackgroundHerein, we aimed to present evidence that Ferulic acid (FA), a phenolic acid, can alleviate high glucose (HG)-induced retinal pigment epithelium (RPE) cell apoptosis and protect retina in db/db mice.MethodsARPE-19 cells (a human RPE cell line) were divided into four groups: control group; HG group (30 mmol/L glucose); HG+FA group (30 mmol/L glucose and 10 mmol/L FA). Cell viability and apoptosis were detected using CCK-8 and Annexin-5 staining, respectively. Apoptosis-related markers including P53, BAX and Bcl2 were examined by RT-qPCR, western blot and immunohistochemistry. Totally, 30 male db/db mice were randomly divided into db/db group (5 ml/kg saline) and FA group (0.05 g/kg FA). After treatment for 2 months, retinal samples were subjected to hematoxylin and eosin (H&E) and Masson staining. Moreover, immunofluorescence was used to detect apoptosis-related markers. Blood samples were collected for measuring cholesterol, triglyceride (TG), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) levels.ResultsFA treatment markedly increased cell viability and suppressed cell apoptosis of ARPE-19 cells compared to the HG-exposed group. Furthermore, FA ameliorated the abnormal expression levels of P53, BAX and Bcl2 in HG-induced ARPE-19 cells. In animal models, FA attenuated pathological changes in the retina tissues of diabetic mice. Consistent with in vitro models, FA significantly ameliorated the expression of apoptosis-related markers in retina tissues. Biochemical test results showed that FA reduced hyperlipidemia in diabetic mice.ConclusionOur findings suggest that FA alleviates HG-induced apoptosis in RPE cells and protects retina in db/db mice, which can be associated with P53 and BAX inactivation and Bcl2 activation. creator: Dejun Zhu creator: Wenqing Zou creator: Xiangmei Cao creator: Weigang Xu creator: Zhaogang Lu creator: Yan Zhu creator: Xiaowen Hu creator: Jin Hu creator: Qing Zhu uri: https://doi.org/10.7717/peerj.13375 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Zhu et al.