title: PeerJ description: Articles published in PeerJ link: https://peerj.com/articles/index.rss3?journal=peerj&page=1053 creator: info@peerj.com PeerJ errorsTo: info@peerj.com PeerJ language: en title: Dual-tasking effects on static and dynamic postural balance performance: a comparison between endurance and team sport athletes link: https://peerj.com/articles/9765 last-modified: 2020-09-16 description: In sports, postural balance control has been demonstrated to be one of the limiting factors of performance and a necessary component to achieve any sport technique. Team players (TP) must process and react to multiple external stimuli while executing at the same time the skills of the game. By contrast, endurance athletes (END) must perform the same gesture repetitively without a concurrent coordination of continuous stimuli-related actions. However, END are used to facilitate their physical performance by adopting cognitive strategies while performing their sport gesture. Therefore, we aimed to investigate static and dynamic balance performance in these two types of athletes, both in single and dual-task conditions. Nineteen END and sixteen TP underwent a static and a dynamic balance assessment on a dynamometric platform and an instrumented oscillating board, respectively. Among TP static but not dynamic postural balance performance was negatively affected by dual-tasking considering the area of the confidence ellipse (p < 0.001; d = 0.52) and the sway path mean speed (p < 0.001; d = 0.93). Conversely, END unaltered static balance performance but showed an overall improvement in the dynamic one when dual-tasking occurred. The limited human processing capacity accounted the worsening of the cognitive performance in both TP (p < 0.05; d = 0.22) and END (p < 0.001; d = 0.37). Although TP are more used coping dual tasking, the better performance of END could be accounted for by the employment of the external attentive focus (i.e. counting backward aloud) that called into play a strategy close to those adopted during training and competitions. These surprising results should be considered when driving and developing new trainings for team players in dual-tasking conditions. creator: Fabio Sarto creator: Giorgia Cona creator: Francesco Chiossi creator: Antonio Paoli creator: Patrizia Bisiacchi creator: Elisabetta Patron creator: Giuseppe Marcolin uri: https://doi.org/10.7717/peerj.9765 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2020 Sarto et al. title: If you build it, they will come: rapid colonization by dragonflies in a new effluent-dependent river reach link: https://peerj.com/articles/9856 last-modified: 2020-09-16 description: BackgroundAquatic ecosystems are greatly altered by urban development, including the complete loss of natural habitat due to water diversions or channel burial. However, novel freshwater habitats also are created in cities, such as effluent-dependent streams that rely on treated wastewater for flow. It is unclear how diverse these novel ecosystems are, or how quickly aquatic species are able to colonize them. In this study, we (1) quantify odonate (Insecta, Odonata) colonization of a novel effluent-dependent river reach, (2) examine how drying events affect odonates in these novel habitats, and (3) explore whether effluent-dependent streams can support diverse odonate assemblages.MethodsWe conducted monthly odonate surveys at three sites along the Santa Cruz River (Tucson, AZ, USA) between June 2019 and May 2020. One site was in a long-established effluent-dependent reach (flowing since the 1970s) that served as a reference site and two sites were in a newly-established reach that began flowing on June 24, 2019 (it was previously dry). We compared odonate species richness, assemblage composition, and colonization patterns across these reaches, and examined how these factors responded to flow cessation events in the new reach.ResultsSeven odonate species were observed at the study sites in the new reach within hours of flow initiation, and species rapidly continued to arrive thereafter. Within 3 months, species richness and assemblage composition of adult odonates were indistinguishable in the new and reference reaches. However, drying events resulted in short-term and chronic reductions in species richness at one of the sites. Across all three sites, we found over 50 odonate species, which represent nearly 40% of species known from the state of Arizona.DiscussionOdonates were surprisingly diverse in the effluent-dependent Santa Cruz River and rapidly colonized a newly established reach. Richness levels remained high at study sites that did not experience drying events. These results suggest that consistent discharge of high-quality effluent into dry streambeds can be an important tool for promoting urban biodiversity. However, it remains to be seen how quickly and effectively less vagile taxa (e.g., mayflies, caddisflies) can colonize novel reaches. Effluent-dependent urban streams will always be highly managed systems, but collaboration between ecologists and urban planners could help to maximize aquatic biodiversity while still achieving goals of public safety and urban development. creator: Michael T. Bogan creator: Drew Eppehimer creator: Hamdhani Hamdhani creator: Kelsey Hollien uri: https://doi.org/10.7717/peerj.9856 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2020 Bogan et al. title: Biological function of Klebsiella variicola and its effect on the rhizosphere soil of maize seedlings link: https://peerj.com/articles/9894 last-modified: 2020-09-16 description: BackgroundDeterioration of the ecological environment in recent years has led to increasing soil salinization, which severely affects the cultivation of agricultural crops. While research has focused on improving soil environment through the application of pollution-free microbial fertilizers, there are relatively few plant growth-promoting bacteria suitable for saline-alkali environments. Although Klebsiella variicola can adapt to saline-alkali environments to successfully colonize rhizosphere microenvironments, only a few studies have investigated its role in promoting crop growth. Its effect on the crop rhizosphere soil microenvironment is especially unclear.MethodsIn this study, the biological function of K. variicola and its colonization in maize seedling rhizosphere soil were studied in detail through selective media and ultraviolet spectrophotometry. The effects of K. variicola on the rhizosphere soil microenvironment and the growth of maize seedlings in saline-alkali and neutral soils were systematically analysed using the colorimetric method, the potassium dichromate volumetric method, and the diffusion absorption method.ResultsOur results showed that K. variicola played a role in indole acetic acid, acetoin, ammonia, phosphorus, and potassium production, as well as in nitrogen fixation. A high level of colonization was observed in the rhizosphere soil of maize seedlings. Following the application of K. variicola in neutral and saline-alkali soils, the nutrient composition of rhizosphere soil of maize seedlings increased in varying degrees, more notably in saline-alkali soil. The content of organic matter, alkali-hydrolysable nitrogen, available phosphorus, available potassium, alkaline phosphatase, sucrase, urease, and catalase increased by 64.22%, 117.39%, 175.64%, 28.63%, 146.08%, 76.77%, 86.60%, and 45.29%, respectively, insaline-alkalisoil.ConclusionK.variicola, therefore, performed a variety of biological functions to promote the growth of maize seedlings and effectively improve the level of soil nutrients and enzymes in the rhizosphere of maize seedlings, undersaline-alkali stress conditions. It played an important role in enhancing the rhizosphere microenvironment of maize seedlings under saline-alkali stress. creator: Lijuan Yang creator: Kejun Yang uri: https://doi.org/10.7717/peerj.9894 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2020 Yang and Yang title: Entomopathogenic fungi decrease Rhizoctonia disease in potato in field conditions link: https://peerj.com/articles/9895 last-modified: 2020-09-16 description: Rhizoctonia potato disease is widespread in the world and causes substantial yield and quality losses in potato. This study aimed to evaluate the efficacy of entomopathogenic fungi Metarhizium robertsii and Beauveria bassiana in the inhibition of potato Rhizoctonia complex disease. The efficacy of the entomopathogenic fungi M. robertsii and B. bassiana in the defense of potato against Rhizoctonia disease (stem cancer, black scrulf and other forms of manifestation on tubers) was estimated under field conditions in Western Siberia. Preplanting treatment of the tubers with B. bassiana decreased Rhizoctonia disease in the stems and stolons. At the same time, treatment with M. robertsii did not cause a decrease in Rhizoctonia disease in these organs. However, both fungi decreased the sclerotium index on the tubers of new crops. We demonstrated two mechanisms of inhibition of Rhizoctonia solani by M. robertsii and B. bassiana, including (1) direct effect, expressed as inhibition of R. solani sclerotium formation in cocultivation assays, and (2) indirect effect, which is associated with increased peroxidase activity in potato roots under the influence of colonization by entomopathogenic fungi. We suggest that the treatment of seed tubers with B. basiana can effectively manage Rhizoctonia disease during the plant vegetative season and that both fungi significantly improve the quality of the new tuber crop. creator: Oksana G. Tomilova creator: Elena M. Shaldyaeva creator: Natalia A. Kryukova creator: Yulia V. Pilipova creator: Natalia S. Schmidt creator: Viktor P. Danilov creator: Vadim Y. Kryukov creator: Viktor V. Glupov uri: https://doi.org/10.7717/peerj.9895 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2020 Tomilova et al. title: Community based actions save Yellow-spotted river turtle (Podocnemis unifilis) eggs and hatchlings flooded by rapid river level rises link: https://peerj.com/articles/9921 last-modified: 2020-09-16 description: The conservation and recovery of increasingly threatened tropical freshwater turtle populations depends on effective management plans and actions. Here we show that community-based actions saved Yellow-spotted river turtle (Podocnemis unifilis) eggs submerged by unseasonal flooding and ensured the release of hatchlings. We recovered 926 eggs and 65 premature hatchlings from 74 submerged nests at 16 flooded nesting areas along 75 km of waterways. The rescued eggs were transferred to a rearing center and incubated. Hatchlings emerged from eggs that had remained underwater for up to two days. Hatchlings were maintained in 250–500 L nursery tanks until yolk sac scars had closed. Healthy hatchlings were then immediately released around the original nesting areas. We released 599 hatchlings (60.4%) from 991 submerged eggs and hatchlings. Egg survival (61.7% (571/926)) was substantially less than hatchling survival (94.2% (599/636)) but within the expected range of values reported for this species. These findings suggest that Yellow-spotted river turtle eggs and embryos are resistant to short-term submersion, which could help explain the widespread distribution of this species across highly seasonal Amazonian rivers. Management plans should take the possible survival of submerged eggs into consideration as part of species conservation and recovery actions. creator: Darren Norris creator: Fernanda Michalski creator: James P. Gibbs uri: https://doi.org/10.7717/peerj.9921 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2020 Norris et al. title: Ultraviolet-reflective film applied to windows reduces the likelihood of collisions for two species of songbird link: https://peerj.com/articles/9926 last-modified: 2020-09-16 description: Perhaps a billion birds die annually from colliding with residential and commercial windows. Therefore, there is a societal need to develop technologies that reduce window collisions by birds. Many current window films that are applied to the external surface of windows have human-visible patterns that are not esthetically preferable. BirdShades have developed a short wavelength (ultraviolet) reflective film that appears as a slight tint to the human eye but should be highly visible to many bird species that see in this spectral range. We performed flight tunnel tests of whether the BirdShades external window film reduced the likelihood that two species of song bird (zebra finch, Taeniopygia guttata and brown-headed cowbird, Molothrus ater) collide with windows during daylight. We paid particular attention to simulate the lighting conditions that birds will experience while flying during the day. Our results indicate a 75–90% reduction in the likelihood of collision with BirdShades-treated compared with control windows, in forced choice trials. In more ecologically relevant comparison between trials where all windows were either treated or control windows, the estimated reduction in probability of collision was 30–50%. Further, both bird species slow their flight by approximately 25% when approaching windows treated with the BirdShades film, thereby reducing the force of collisions if they were to happen. Therefore, we conclude that the BirdShades external window film will be effective in reducing the risk of and damage caused to populations and property by birds’ collision with windows. As this ultraviolet-reflective film has no human-visible patterning to it, the product might be an esthetically more acceptable low cost solution to reducing bird-window collisions. Further, we call for testing of other mitigation technologies in lighting and ecological conditions that are more similar to what birds experience in real human-built environments and make suggestions for testing standards to assess collision-reducing technologies. creator: John P. Swaddle creator: Lauren C. Emerson creator: Robin G. Thady creator: Timothy J. Boycott uri: https://doi.org/10.7717/peerj.9926 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2020 Swaddle et al. title: Seasonal variations in leaf and branch trace elements and the influence of a 3-yr 100% rainfall exclusion on Pinus massoniana Lamb link: https://peerj.com/articles/9935 last-modified: 2020-09-16 description: BackgroundTrace elements are essential for the growth and survival of plants, and their concentrations and distributions in plants are effective reflections of ecological adaptation strategies. However, this aspect has seldom been addressed.MethodChanges in the leaf and branch trace elements of Pinus massoniana Lamb, induced by seasonal dynamics and in response to a 3-yr 100% rainfall exclusion, were evaluated.ResultsThe results showed that the concentrations of Fe, Cu, Zn, Cd, Ni and Cr in leaves of P. massoniana in the control group had high seasonal resolution. There were three groups according to their patterns over the growing season: (1) nutrient elements (Cu, Zn, Ni and Cd), which continuously decreased in concentration during the growing season, with the highest concentration in spring and the lowest in autumn; (2) accumulating element (Cr), which increased in concentration from spring to autumn; and (3) indifferent element (Fe), which increased in concentration from spring to summer and decreased in concentration from summer to autumn. The concentrations of trace elements in leaves and branches showed no significant differences with mild drought stress, except for Fe and Cr in leaves and Cr in branches, which significantly increased (p < 0.05) under the result of self-selection under mild drought stress. Therefore, the resultant seasonal and drought effects on trace element cycling in P. massoniana could provide theoretical support to respond to future climate change. creator: Tian Lin creator: Xuanmei Zheng creator: Huaizhou Zheng uri: https://doi.org/10.7717/peerj.9935 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2020 Lin et al. title: Nitrogen form plays an important role in the growth of moso bamboo (Phyllostachys edulis) seedlings link: https://peerj.com/articles/9938 last-modified: 2020-09-16 description: BackgroundThis study aimed to gain an understanding of the growth response of Phyllostachys edulis (moso bamboo) seedlings to nitrogen (N) and potassium (K) to benefit nutrient management practices and the design of proper fertilizer in nursery cultivation.MethodsAn orthogonal array L8(4×24) was used to study the effects of N forms (NH4+, NO3−), N concentrations (8, 32 mmol/L), and K+concentrations (0, 0.5, 1.5, 3 mmol/L) on seedling height, leaf number, chlorophyll content (SPAD value), biomass, root systems, and N content of P. edulis seedlings. Plants were grown in vermiculite under controlled greenhouse conditions.ResultsOur study showed that N form played a significant role in the overall performance of P. edulis seedlings, followed by the effect of N and K+ concentrations. Among the N forms, NH4+ significantly improved the growth of P. edulis seedlings compared with NO3−. Seedling height, leaf number, chlorophyll SPAD value, biomass, and root system architecture (root length, root surface area, root volume, and root tips) were greater with 8 mmol/L of NH4+ treatments than with 32 mmol/L of NH4+treatments, whereas root diameter and N content of P. edulis seedlings were higher with 32 mmol/L of NH4+ than with 8 mmol/L of NH4+. K displayed inconsistent effects on the growth of P. edulis seedlings. Specifically, seedling height, leaf number, biomass and root volume increased when the K+ concentration was increased from 0 to 0.5 mmol/L, followed by a decrease when the K+ concentration was further increased from 0.5 to 3 mmol/L. Root average diameter of the seedlings was the highest with a K+ concentration of 1.5 mmol/L, and K had some inhibitory effects on the chlorophyll SPAD value of the seedlings. P. edulis seedlings performed well with 8 mmol/L NH4+and further tolerated a higher concentration of both NH4+ and NO3−, although excessive N could inhibit seedling growth. A lower concertation of K (≤ 0.5 mmol/L) promoted seedling growth and increasing K+ concentration in the nutrient solution did not alleviate the inhibitory effect of high N on the growth of P. edulis seedlings. Therefore, NH4+nitrogen as the main form of N fertilizer, together with a low concertation of K+, should be supplied in the cultivation and nutrient management practices of moso bamboo. creator: Na Zou creator: Ling Huang creator: Huijing Chen creator: Xiaofeng Huang creator: Qingni Song creator: Qingpei Yang creator: Tianchi Wang uri: https://doi.org/10.7717/peerj.9938 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2020 Zou et al. title: An empirical examination of sample size effects on population demographic estimates in birds using single nucleotide polymorphism (SNP) data link: https://peerj.com/articles/9939 last-modified: 2020-09-16 description: Sample size is a critical aspect of study design in population genomics research, yet few empirical studies have examined the impacts of small sample sizes. We used datasets from eight diverging bird lineages to make pairwise comparisons at different levels of taxonomic divergence (populations, subspecies, and species). Our data are from loci linked to ultraconserved elements and our analyses used one single nucleotide polymorphism per locus. All individuals were genotyped at all loci, effectively doubling sample size for coalescent analyses. We estimated population demographic parameters (effective population size, migration rate, and time since divergence) in a coalescent framework using Diffusion Approximation for Demographic Inference, an allele frequency spectrum method. Using divergence-with-gene-flow models optimized with full datasets, we subsampled at sequentially smaller sample sizes from full datasets of 6–8 diploid individuals per population (with both alleles called) down to 1:1, and then we compared estimates and their changes in accuracy. Accuracy was strongly affected by sample size, with considerable differences among estimated parameters and among lineages. Effective population size parameters (ν) tended to be underestimated at low sample sizes (fewer than three diploid individuals per population, or 6:6 haplotypes in coalescent terms). Migration (m) was fairly consistently estimated until <2 individuals per population, and no consistent trend of over-or underestimation was found in either time since divergence (T) or theta (Θ = 4Nrefμ). Lineages that were taxonomically recognized above the population level (subspecies and species pairs; that is, deeper divergences) tended to have lower variation in scaled root mean square error of parameter estimation at smaller sample sizes than population-level divergences, and many parameters were estimated accurately down to three diploid individuals per population. Shallower divergence levels (i.e., populations) often required at least five individuals per population for reliable demographic inferences using this approach. Although divergence levels might be unknown at the outset of study design, our results provide a framework for planning appropriate sampling and for interpreting results if smaller sample sizes must be used. creator: Jessica F. McLaughlin creator: Kevin Winker uri: https://doi.org/10.7717/peerj.9939 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2020 McLaughlin and Winker title: Galectin-3 not Galectin-9 as a candidate prognosis marker for hepatocellular carcinoma link: https://peerj.com/articles/9949 last-modified: 2020-09-16 description: BackgroundGalectins (Gal) are a family of protein that bind to the β-galactoside of glycoproteins. It modulates a variety of biological functions, such as tumor growth, angiogenesis and tumor metastasis. A series of experimental and clinical evidences have been reported to support a correlation between galectin expressions and neoplastic transformation, progression and prognosis. The objective of this study was to estimate the expression of Gal-3 and Gal-9 in order to evaluate their relation to hepatocellular carcinoma (HCC) -related clinical features and their prognostic values.MethodsWe evaluated Gal-3 and Gal-9 expression in 247 HCC patients by a tissue microarray immunohistochemistry method, then analyzed the relationship between expression levels of Gal-3 and Gal-9 protein and tumor parameters or clinical outcomes.ResultsThe Gal-3 expression was significantly higher in tumor tissues compared with adjacent non-tumor tissues (P < 0.001), while no significant differences of Gal-9 was detected (P = 0.222). A higher Gal-3 expression was significantly associated with lymph-vascular invasion (P = 0.049), poor histological differentiation (P = 0.016), and no cirrhosis (P = 0.040). In contrast, a lower Gal-9 expression was related to lymph-vascular invasion (P = 0.012) and poor histological differentiation (P = 0.002). Survival analysis showed that patients with higher Gal-3 expression had worse overall survival (P = 0.012) , however no correlation was found between Gal-9 expression and survival (P = 0.185). Multivariate analysis showed that multiple tumor (HR = 1.94, 95% CI [1.36–2.78]), tumor size ≥ 5 cm (HR = 1.51, 95% CI [1.07–2.12]), Lymph-vascular invasion (HR = 1.45, 95% CI [1.00–2.10]) and Gal-3 expression (HR = 1.57, 95% CI [1.06–2.33]) were independent influencing factors of prognosis in patients with hepatocellular carcinoma.ConclusionGal-3 was expected to serve as a novel prognostic marker of hepatocellular carcinoma, while Gal-9 expression was only related to tumor progression. creator: Fei Kong creator: Meishan Jin creator: Donghui Cao creator: Zhifang Jia creator: Yawen Liu creator: Jing Jiang uri: https://doi.org/10.7717/peerj.9949 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2020 Kong et al.