PeerJ
type: channel
link: https://peerj.com/articles/
description: Articles published in PeerJ
publisher: PeerJ Inc.
publication name: PeerJ
issn: 2167-8359
items: Pollution of the sediments of the coastal zone of the Sambia Peninsula and the Curonian Spit (Southeastern Baltic Sea)
items: A new species of Pseudopaludicola (Anura, Leiuperinae) from Espírito Santo, Brazil
items: Integrated bioinformatic changes and analysis of retina with time in diabetic rats
items: Occurrence of termites (Isoptera) on living and standing dead trees in a tropical dry forest in Mexico
items: Overwintering temperature and body condition shift emergence dates of spring-emerging solitary bees
items: Identification of potential crucial genes and pathways associated with vein graft restenosis based on gene expression analysis in experimental rabbits
items: Coarse- and fine-scale patterns of distribution and habitat selection places an Amazonian floodplain curassow in double jeopardy
items: Modelling the growth of the brown frog (Rana dybowskii)
items: Breast fibroblasts in both cancer and normal tissues induce phenotypic transformation of breast cancer stem cells: a preliminary study
items: Latent profiles of elite Malaysian athletes’ use of psychological skills and techniques and relations with mental toughness

Pollution of the sediments of the coastal zone of the Sambia Peninsula and the Curonian Spit (Southeastern Baltic Sea)
type: item
type: AcademicArticle
description: The detailed environmental survey of the coastal zone of the Kaliningrad Region northern coast was carried out. The pollutants distribution in the silty clay fraction and calculation of ecological indexes allowed the evaluation of distribution of potentially harmful elements (PHEs). The sources of pollution in the most intensively used areas were identified, and transit and accumulation zones were allocated. A large area of anomalous content of PHEs was revealed on the underwater coastal slope of the Curonian Spit National Park, which is situated far from the sources of pollution. The alongshore bed load transport provides the contamination of the underwater slope whereas the beaches are less exposed to pollution.
format: application/pdf
format: text/html
creator: Alexander Krek
creator: Viktor Krechik
creator: Aleksandr Danchenkov
creator: Elena Krek
subject: Aquatic and Marine Chemistry
subject: Environmental Contamination and Remediation
description: doi:10.7717/peerj.4770
publisher: PeerJ Inc.
rights: © 2018 Krek et al.
abstract: The detailed environmental survey of the coastal zone of the Kaliningrad Region northern coast was carried out. The pollutants distribution in the silty clay fraction and calculation of ecological indexes allowed the evaluation of distribution of potentially harmful elements (PHEs). The sources of pollution in the most intensively used areas were identified, and transit and accumulation zones were allocated. A large area of anomalous content of PHEs was revealed on the underwater coastal slope of the Curonian Spit National Park, which is situated far from the sources of pollution. The alongshore bed load transport provides the contamination of the underwater slope whereas the beaches are less exposed to pollution.
bibliographic citation: Krek et al. (2018) Pollution of the sediments of the coastal zone of the Sambia Peninsula and the Curonian Spit (Southeastern Baltic Sea). PeerJ 6:e4770 https://doi.org/10.7717/peerj.4770
date submitted: 2018-02-01
date accepted: 2018-04-24
issued: 2018-05-16
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Krek
  given name: Alexander
author list: Agent
  family name: Krechik
  given name: Viktor
author list: Agent
  family name: Danchenkov
  given name: Aleksandr
author list: Agent
  family name: Krek
  given name: Elena
doi: 10.7717/peerj.4770
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-05-16
copyright: ©2018 Krek et al.
attribution name: Krek et al.

A new species of Pseudopaludicola (Anura, Leiuperinae) from Espírito Santo, Brazil
type: item
type: AcademicArticle
description: We describe a new anuran species of the genus Pseudopaludicola that inhabits sandy areas in resting as associated to the Atlantic Forest biome in the state of Espírito Santo, Brazil. The new species is characterized by: SVL 11.7–14.6 mm in males, 14.0–16.7 mm in females; body slender; fingertips knobbed, with a central groove; hindlimbs short; abdominal fold complete; arytenoid cartilages wide; prepollex with base and two segments; prehallux with base and one segment; frontoparietal fontanelle partially exposed; advertisement call with one note composed of two isolated pulses per call; call dominant frequency ranging 4,380–4,884 Hz; diploid chromosome number 22; and Ag-NORs on 8q subterminal. In addition, its 16S rDNA sequence shows high genetic distances when compared to sequences of related species, which provides strong evidence that the new species is an independent lineage.
format: application/pdf
format: text/html
creator: Dario E. Cardozo
creator: Diego Baldo
creator: Nadya Pupin
creator: João Luiz Gasparini
creator: Célio F. Baptista Haddad
subject: Biodiversity
subject: Taxonomy
subject: Zoology
description: doi:10.7717/peerj.4766
publisher: PeerJ Inc.
rights: © 2018 Cardozo et al.
abstract: We describe a new anuran species of the genus Pseudopaludicola that inhabits sandy areas in resting as associated to the Atlantic Forest biome in the state of Espírito Santo, Brazil. The new species is characterized by: SVL 11.7–14.6 mm in males, 14.0–16.7 mm in females; body slender; fingertips knobbed, with a central groove; hindlimbs short; abdominal fold complete; arytenoid cartilages wide; prepollex with base and two segments; prehallux with base and one segment; frontoparietal fontanelle partially exposed; advertisement call with one note composed of two isolated pulses per call; call dominant frequency ranging 4,380–4,884 Hz; diploid chromosome number 22; and Ag-NORs on 8q subterminal. In addition, its 16S rDNA sequence shows high genetic distances when compared to sequences of related species, which provides strong evidence that the new species is an independent lineage.
bibliographic citation: Cardozo et al. (2018) A new species of Pseudopaludicola (Anura, Leiuperinae) from Espírito Santo, Brazil. PeerJ 6:e4766 https://doi.org/10.7717/peerj.4766
date submitted: 2018-01-26
date accepted: 2018-04-17
issued: 2018-05-16
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Cardozo
  given name: Dario E.
author list: Agent
  family name: Baldo
  given name: Diego
author list: Agent
  family name: Pupin
  given name: Nadya
author list: Agent
  family name: Gasparini
  given name: João Luiz
author list: Agent
  family name: Baptista Haddad
  given name: Célio F.
doi: 10.7717/peerj.4766
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-05-16
copyright: ©2018 Cardozo et al.
attribution name: Cardozo et al.

Integrated bioinformatic changes and analysis of retina with time in diabetic rats
type: item
type: AcademicArticle
description: Diabetic retinopathy (DR) is the most common chronic complication of diabetes. It can cause impaired vision and even blindness. However, the pathological mechanism of DR is still unknown. In the present study, we use bioinformatic analysis to reveal the pathological changes of early DR in a streptozotocin (STZ) induced diabetes rat model. The dataset GSE28831 was downloaded from the Gene Expression Omnibus (GEO) database. To clarify the pathological mechanism of early DR, genes which were up-regulated (UP group) or down-regulated (DOWN group) over time were identified. One hundred eighty six genes in the UP group and 85 genes in the DOWN group were defined. There were in total 28 Gene ontology (GO) terms with a P value lower than 0.05 in UP group, including astrocyte development, neutrophil chemotaxis, neutrophil aggregation, mesenchymal cell proliferation and so on. In the DOWN group, there were totally 14 GO terms with a P value lower than 0.05, including visual perception, lens development in camera-type eye, camera-type eye development, bicellular tight junction and so on. Signaling pathways were analyzed with all genes in the UP and DOWN groups, and leukocyte transendothelial migration and tight junction were selected. Protein–protein interaction (PPI) network was constructed and six hub genes Diras3, Actn1, Tssk6, Cnot6l, Tek and Fgf4 were selected with connection degree ≥5. S100a8, S100a9 and Tek may be potential targets for DR diagnosis and treatment. This study provides the basis for the diagnosis and treatment of DR in the future.
format: application/pdf
format: text/html
creator: Zekai Cui
creator: Qiaolang Zeng
creator: Yonglong Guo
creator: Shiwei Liu
creator: Jiansu Chen
subject: Bioinformatics
subject: Ophthalmology
description: doi:10.7717/peerj.4762
publisher: PeerJ Inc.
rights: © 2018 Cui et al.
abstract: Diabetic retinopathy (DR) is the most common chronic complication of diabetes. It can cause impaired vision and even blindness. However, the pathological mechanism of DR is still unknown. In the present study, we use bioinformatic analysis to reveal the pathological changes of early DR in a streptozotocin (STZ) induced diabetes rat model. The dataset GSE28831 was downloaded from the Gene Expression Omnibus (GEO) database. To clarify the pathological mechanism of early DR, genes which were up-regulated (UP group) or down-regulated (DOWN group) over time were identified. One hundred eighty six genes in the UP group and 85 genes in the DOWN group were defined. There were in total 28 Gene ontology (GO) terms with a P value lower than 0.05 in UP group, including astrocyte development, neutrophil chemotaxis, neutrophil aggregation, mesenchymal cell proliferation and so on. In the DOWN group, there were totally 14 GO terms with a P value lower than 0.05, including visual perception, lens development in camera-type eye, camera-type eye development, bicellular tight junction and so on. Signaling pathways were analyzed with all genes in the UP and DOWN groups, and leukocyte transendothelial migration and tight junction were selected. Protein–protein interaction (PPI) network was constructed and six hub genes Diras3, Actn1, Tssk6, Cnot6l, Tek and Fgf4 were selected with connection degree ≥5. S100a8, S100a9 and Tek may be potential targets for DR diagnosis and treatment. This study provides the basis for the diagnosis and treatment of DR in the future.
bibliographic citation: Cui et al. (2018) Integrated bioinformatic changes and analysis of retina with time in diabetic rats. PeerJ 6:e4762 https://doi.org/10.7717/peerj.4762
date submitted: 2017-12-21
date accepted: 2018-04-23
issued: 2018-05-16
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Cui
  given name: Zekai
author list: Agent
  family name: Zeng
  given name: Qiaolang
author list: Agent
  family name: Guo
  given name: Yonglong
author list: Agent
  family name: Liu
  given name: Shiwei
author list: Agent
  family name: Chen
  given name: Jiansu
doi: 10.7717/peerj.4762
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-05-16
copyright: ©2018 Cui et al.
attribution name: Cui et al.

Occurrence of termites (Isoptera) on living and standing dead trees in a tropical dry forest in Mexico
type: item
type: AcademicArticle
description: Termites play a key role as ecosystem engineers in numerous ecological processes though their role in the dynamics of wood degradation in tropical dry forests, particularly at the level of the crown canopy, has been little studied. In this study, we analysed the occurrence of termites in the forest canopy by evaluating the density and proportion of living and standing dead trees associated with termites in deciduous and riparian habitats of the tropical dry forest in Chamela, Mexico. The results indicated that 60–98% of standing dead trees and 23–59% of living trees in Chamela were associated with termites. In particular, we found that the density of standing dead trees was higher in deciduous forests (0.057–0.066 trees/m2) than in riparian forests (0.022 and 0.027 trees/m2), even though the proportion of trees was not significantly different among habitats. Additionally, we found a higher density of trees associated with termites in trees of smaller size classes (0.01–0.09 trees/m2) than in larger class sizes (0–0.02 trees/m2). Interestingly, 72% of variation in the density of trees associated with termites is explained by the density of standing dead trees. Overall, these results indicate that standing dead tree availability might be the main factor regulating termite populations in Chamela forest and suggest that termites could play a key role in the decomposition of above-ground dead wood, mediating the incorporation of suspended and standing dead wood into the soil.
format: application/pdf
format: text/html
creator: Nancy Calderón-Cortés
creator: Luis H. Escalera-Vázquez
creator: Ken Oyama
subject: Ecosystem Science
subject: Forestry
description: doi:10.7717/peerj.4731
publisher: PeerJ Inc.
rights: © 2018 Calderón-Cortés et al.
abstract: Termites play a key role as ecosystem engineers in numerous ecological processes though their role in the dynamics of wood degradation in tropical dry forests, particularly at the level of the crown canopy, has been little studied. In this study, we analysed the occurrence of termites in the forest canopy by evaluating the density and proportion of living and standing dead trees associated with termites in deciduous and riparian habitats of the tropical dry forest in Chamela, Mexico. The results indicated that 60–98% of standing dead trees and 23–59% of living trees in Chamela were associated with termites. In particular, we found that the density of standing dead trees was higher in deciduous forests (0.057–0.066 trees/m2) than in riparian forests (0.022 and 0.027 trees/m2), even though the proportion of trees was not significantly different among habitats. Additionally, we found a higher density of trees associated with termites in trees of smaller size classes (0.01–0.09 trees/m2) than in larger class sizes (0–0.02 trees/m2). Interestingly, 72% of variation in the density of trees associated with termites is explained by the density of standing dead trees. Overall, these results indicate that standing dead tree availability might be the main factor regulating termite populations in Chamela forest and suggest that termites could play a key role in the decomposition of above-ground dead wood, mediating the incorporation of suspended and standing dead wood into the soil.
bibliographic citation: Calderón-Cortés et al. (2018) Occurrence of termites (Isoptera) on living and standing dead trees in a tropical dry forest in Mexico. PeerJ 6:e4731 https://doi.org/10.7717/peerj.4731
date submitted: 2018-02-07
date accepted: 2018-04-15
issued: 2018-05-16
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Calderón-Cortés
  given name: Nancy
author list: Agent
  family name: Escalera-Vázquez
  given name: Luis H.
author list: Agent
  family name: Oyama
  given name: Ken
doi: 10.7717/peerj.4731
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-05-16
copyright: ©2018 Calderón-Cortés et al.
attribution name: Calderón-Cortés et al.

Overwintering temperature and body condition shift emergence dates of spring-emerging solitary bees
type: item
type: AcademicArticle
description: Solitary bees in seasonal environments must align their life-cycles with favorable environmental conditions and resources; the timing of their emergence is highly fitness relevant. In several bee species, overwintering temperature influences both emergence date and body weight at emergence. High variability in emergence dates among specimens overwintering at the same temperatures suggests that the timing of emergence also depends on individual body conditions. However, possible causes for this variability, such as individual differences in body size or weight, have been rarely studied. In a climate chamber experiment using two spring-emerging mason bees (Osmia cornuta and O. bicornis), we investigated the relationship between temperature, emergence date, body weight, and body size, the last of which is not affected by overwintering temperature. Our study showed that body weight declined during hibernation more strongly in warm than in cold overwintering temperatures. Although bees emerged earlier in warm than in cold overwintering temperatures, at the time of emergence, bees in warm overwintering temperatures had lower body weights than bees in cold overwintering temperatures (exception of male O. cornuta). Among specimens that experienced the same overwintering temperatures, small and light bees emerged later than their larger and heavier conspecifics. Using a simple mechanistic model we demonstrated that spring-emerging solitary bees use a strategic approach and emerge at a date that is most promising for their individual fitness expectations. Our results suggest that warmer overwintering temperatures reduce bee fitness by causing a decrease in body weight at emergence. We showed furthermore that in order to adjust their emergence dates, bees use not only temperature but also their individual body condition as triggers. This may explain differing responses to climate warming within and among bee populations and may have consequences for bee-plant interactions as w…
format: application/pdf
format: text/html
creator: Mariela Schenk
creator: Oliver Mitesser
creator: Thomas Hovestadt
creator: Andrea Holzschuh
subject: Ecology
subject: Entomology
subject: Zoology
description: doi:10.7717/peerj.4721
publisher: PeerJ Inc.
rights: © 2018 Schenk et al.
abstract: Solitary bees in seasonal environments must align their life-cycles with favorable environmental conditions and resources; the timing of their emergence is highly fitness relevant. In several bee species, overwintering temperature influences both emergence date and body weight at emergence. High variability in emergence dates among specimens overwintering at the same temperatures suggests that the timing of emergence also depends on individual body conditions. However, possible causes for this variability, such as individual differences in body size or weight, have been rarely studied. In a climate chamber experiment using two spring-emerging mason bees (Osmia cornuta and O. bicornis), we investigated the relationship between temperature, emergence date, body weight, and body size, the last of which is not affected by overwintering temperature. Our study showed that body weight declined during hibernation more strongly in warm than in cold overwintering temperatures. Although bees emerged earlier in warm than in cold overwintering temperatures, at the time of emergence, bees in warm overwintering temperatures had lower body weights than bees in cold overwintering temperatures (exception of male O. cornuta). Among specimens that experienced the same overwintering temperatures, small and light bees emerged later than their larger and heavier conspecifics. Using a simple mechanistic model we demonstrated that spring-emerging solitary bees use a strategic approach and emerge at a date that is most promising for their individual fitness expectations. Our results suggest that warmer overwintering temperatures reduce bee fitness by causing a decrease in body weight at emergence. We showed furthermore that in order to adjust their emergence dates, bees use not only temperature but also their individual body condition as triggers. This may explain differing responses to climate warming within and among bee populations and may have consequences for bee-plant interactions as w…
bibliographic citation: Schenk et al. (2018) Overwintering temperature and body condition shift emergence dates of spring-emerging solitary bees. PeerJ 6:e4721 https://doi.org/10.7717/peerj.4721
date submitted: 2017-11-30
date accepted: 2018-04-16
issued: 2018-05-16
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Schenk
  given name: Mariela
author list: Agent
  family name: Mitesser
  given name: Oliver
author list: Agent
  family name: Hovestadt
  given name: Thomas
author list: Agent
  family name: Holzschuh
  given name: Andrea
doi: 10.7717/peerj.4721
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-05-16
copyright: ©2018 Schenk et al.
attribution name: Schenk et al.

Identification of potential crucial genes and pathways associated with vein graft restenosis based on gene expression analysis in experimental rabbits
type: item
type: AcademicArticle
description: Occlusive artery disease (CAD) is the leading cause of death worldwide. Bypass graft surgery remains the most prevalently performed treatment for occlusive arterial disease, and veins are the most frequently used conduits for surgical revascularization. However, the clinical efficacy of bypass graft surgery is highly affected by the long-term potency rates of vein grafts, and no optimal treatments are available for the prevention of vein graft restenosis (VGR) at present. Hence, there is an urgent need to improve our understanding of the molecular mechanisms involved in mediating VGR. The past decade has seen the rapid development of genomic technologies, such as genome sequencing and microarray technologies, which will provide novel insights into potential molecular mechanisms involved in the VGR program. Ironically, high throughput data associated with VGR are extremely scarce. The main goal of the current study was to explore potential crucial genes and pathways associated with VGR and to provide valid biological information for further investigation of VGR. A comprehensive bioinformatics analysis was performed using high throughput gene expression data. Differentially expressed genes (DEGs) were identified using the R and Bioconductor packages. After functional enrichment analysis of the DEGs, protein–protein interaction (PPI) network and sub-PPI network analyses were performed. Finally, nine potential hub genes and fourteen pathways were identified. These hub genes may interact with each other and regulate the VGR program by modulating the cell cycle pathway. Future studies focusing on revealing the specific cellular and molecular mechanisms of these key genes and pathways involved in regulating the VGR program may provide novel therapeutic targets for VGR inhibition.
format: application/pdf
format: text/html
creator: Qiang Liu
creator: Xiujie Yin
creator: Mingzhu Li
creator: Li Wan
creator: Liqiao Liu
creator: Xiang Zhong
creator: Zhuoqi Liu
creator: Qun Wang
subject: Bioinformatics
subject: Cell Biology
subject: Genetics
subject: Genomics
subject: Cardiology
description: doi:10.7717/peerj.4704
publisher: PeerJ Inc.
rights: © 2018 Liu et al.
abstract: Occlusive artery disease (CAD) is the leading cause of death worldwide. Bypass graft surgery remains the most prevalently performed treatment for occlusive arterial disease, and veins are the most frequently used conduits for surgical revascularization. However, the clinical efficacy of bypass graft surgery is highly affected by the long-term potency rates of vein grafts, and no optimal treatments are available for the prevention of vein graft restenosis (VGR) at present. Hence, there is an urgent need to improve our understanding of the molecular mechanisms involved in mediating VGR. The past decade has seen the rapid development of genomic technologies, such as genome sequencing and microarray technologies, which will provide novel insights into potential molecular mechanisms involved in the VGR program. Ironically, high throughput data associated with VGR are extremely scarce. The main goal of the current study was to explore potential crucial genes and pathways associated with VGR and to provide valid biological information for further investigation of VGR. A comprehensive bioinformatics analysis was performed using high throughput gene expression data. Differentially expressed genes (DEGs) were identified using the R and Bioconductor packages. After functional enrichment analysis of the DEGs, protein–protein interaction (PPI) network and sub-PPI network analyses were performed. Finally, nine potential hub genes and fourteen pathways were identified. These hub genes may interact with each other and regulate the VGR program by modulating the cell cycle pathway. Future studies focusing on revealing the specific cellular and molecular mechanisms of these key genes and pathways involved in regulating the VGR program may provide novel therapeutic targets for VGR inhibition.
bibliographic citation: Liu et al. (2018) Identification of potential crucial genes and pathways associated with vein graft restenosis based on gene expression analysis in experimental rabbits. PeerJ 6:e4704 https://doi.org/10.7717/peerj.4704
date submitted: 2017-12-01
date accepted: 2018-04-15
issued: 2018-05-16
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Liu
  given name: Qiang
author list: Agent
  family name: Yin
  given name: Xiujie
author list: Agent
  family name: Li
  given name: Mingzhu
author list: Agent
  family name: Wan
  given name: Li
author list: Agent
  family name: Liu
  given name: Liqiao
author list: Agent
  family name: Zhong
  given name: Xiang
author list: Agent
  family name: Liu
  given name: Zhuoqi
author list: Agent
  family name: Wang
  given name: Qun
doi: 10.7717/peerj.4704
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-05-16
copyright: ©2018 Liu et al.
attribution name: Liu et al.

Coarse- and fine-scale patterns of distribution and habitat selection places an Amazonian floodplain curassow in double jeopardy
type: item
type: AcademicArticle
description: Patterns of habitat selection are influenced by local productivity, resource availability, and predation risk. Species have taken millions of years to hone the macro- and micro-habitats they occupy, but these may now overlap with contemporary human threats within natural species ranges. Wattled Curassow (Crax globulosa), an endemic galliform species of the western Amazon, is threatened by both hunting and habitat loss, and is restricted to white-water floodplain forests of major Amazonian rivers. In this study conducted along the Juruá River, Amazonas, Brazil, we quantified the ranging ecology and fine-scale patterns of habitat selection of the species. We estimated the home range size of C. globulosa using conventional VHF telemetry. To estimate patterns of habitat selection, we used geo-locations of day ranges to examine the extent and intensity of use across the floodplain, which were then compared to a high-resolution flood map of the study area. We captured two females and one male, which we monitored for 13 months between September 2014 and September 2015. Average home range size was 283 ha, based on the 95% aLoCoH estimator. Wattled Curassows selected areas of prolonged flood pulses (six to eight months/year) and had a consistent tendency to be near open water, usually in close proximity to river banks and lakes, especially during the dry season. Amazonian floodplains are densely settled, and the small portions of floodplain habitat used by Wattled Curassows are both the most accessible to hunters and most vulnerable to deforestation. As a result, the geographic and ecological distribution of Wattled Curassows places them at much higher extinction risk at multiple spatial scales, highlighting the need to consider habitat preferences within their conservation strategy.
format: application/pdf
format: text/html
creator: Gabriel A. Leite
creator: Izeni P. Farias
creator: André L. S. Gonçalves
creator: Joseph E. Hawes
creator: Carlos A. Peres
subject: Conservation Biology
subject: Ecology
description: doi:10.7717/peerj.4617
publisher: PeerJ Inc.
rights: © 2018 Leite et al.
abstract: Patterns of habitat selection are influenced by local productivity, resource availability, and predation risk. Species have taken millions of years to hone the macro- and micro-habitats they occupy, but these may now overlap with contemporary human threats within natural species ranges. Wattled Curassow (Crax globulosa), an endemic galliform species of the western Amazon, is threatened by both hunting and habitat loss, and is restricted to white-water floodplain forests of major Amazonian rivers. In this study conducted along the Juruá River, Amazonas, Brazil, we quantified the ranging ecology and fine-scale patterns of habitat selection of the species. We estimated the home range size of C. globulosa using conventional VHF telemetry. To estimate patterns of habitat selection, we used geo-locations of day ranges to examine the extent and intensity of use across the floodplain, which were then compared to a high-resolution flood map of the study area. We captured two females and one male, which we monitored for 13 months between September 2014 and September 2015. Average home range size was 283 ha, based on the 95% aLoCoH estimator. Wattled Curassows selected areas of prolonged flood pulses (six to eight months/year) and had a consistent tendency to be near open water, usually in close proximity to river banks and lakes, especially during the dry season. Amazonian floodplains are densely settled, and the small portions of floodplain habitat used by Wattled Curassows are both the most accessible to hunters and most vulnerable to deforestation. As a result, the geographic and ecological distribution of Wattled Curassows places them at much higher extinction risk at multiple spatial scales, highlighting the need to consider habitat preferences within their conservation strategy.
bibliographic citation: Leite et al. (2018) Coarse- and fine-scale patterns of distribution and habitat selection places an Amazonian floodplain curassow in double jeopardy. PeerJ 6:e4617 https://doi.org/10.7717/peerj.4617
date submitted: 2018-01-24
date accepted: 2018-03-24
issued: 2018-05-16
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Leite
  given name: Gabriel A.
author list: Agent
  family name: Farias
  given name: Izeni P.
author list: Agent
  family name: Gonçalves
  given name: André L. S.
author list: Agent
  family name: Hawes
  given name: Joseph E.
author list: Agent
  family name: Peres
  given name: Carlos A.
doi: 10.7717/peerj.4617
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-05-16
copyright: © 2018 Leite et al.
attribution name: Leite et al.

Modelling the growth of the brown frog (Rana dybowskii)
type: item
type: AcademicArticle
description: Well-controlled development leads to uniform body size and a better growth rate; therefore, the ability to determine the growth rate of frogs and their period of sexual maturity is essential for producing healthy, high-quality descendant frogs. To establish a working model that can best predict the growth performance of frogs, the present study examined the growth of one-year-old and two-year-old brown frogs (Rana dybowskii) from metamorphosis to hibernation (18 weeks) and out-hibernation to hibernation (20 weeks) under the same environmental conditions. Brown frog growth was studied and mathematically modelled using various nonlinear, linear, and polynomial functions. The model input values were statistically evaluated using parameters such as the Akaike’s information criterion. The body weight/size ratio (Kwl) and Fulton’s condition factor (K) were used to compare the weight and size of groups of frogs during the growth period. The results showed that the third- and fourth-order polynomial models provided the most consistent predictions of body weight for age 1 and age 2 brown frogs, respectively. Both the Gompertz and third-order polynomial models yielded similarly adequate results for the body size of age 1 brown frogs, while the Janoschek model produced a similarly adequate result for the body size of age 2 brown frogs. The Brody and Janoschek models yielded the highest and lowest estimates of asymptotic weight, respectively, for the body weights of all frogs. The Kwl value of all frogs increased from 0.40 to 3.18. The K value of age 1 frogs decreased from 23.81 to 9.45 in the first four weeks. The K value of age 2 frogs remained close to 10. Graphically, a sigmoidal trend was observed for body weight and body size with increasing age. The results of this study will be useful not only for amphibian research but also for frog farming management strategies and decisions.
format: application/pdf
format: text/html
creator: Qing Tong
creator: Xiao-peng Du
creator: Zong-fu Hu
creator: Li-yong Cui
creator: Hong-bin Wang
subject: Agricultural Science
subject: Aquaculture
subject: Fisheries and Fish Science
subject: Zoology
description: doi:10.7717/peerj.4587
publisher: PeerJ Inc.
rights: © 2018 Tong et al.
abstract: Well-controlled development leads to uniform body size and a better growth rate; therefore, the ability to determine the growth rate of frogs and their period of sexual maturity is essential for producing healthy, high-quality descendant frogs. To establish a working model that can best predict the growth performance of frogs, the present study examined the growth of one-year-old and two-year-old brown frogs (Rana dybowskii) from metamorphosis to hibernation (18 weeks) and out-hibernation to hibernation (20 weeks) under the same environmental conditions. Brown frog growth was studied and mathematically modelled using various nonlinear, linear, and polynomial functions. The model input values were statistically evaluated using parameters such as the Akaike’s information criterion. The body weight/size ratio (Kwl) and Fulton’s condition factor (K) were used to compare the weight and size of groups of frogs during the growth period. The results showed that the third- and fourth-order polynomial models provided the most consistent predictions of body weight for age 1 and age 2 brown frogs, respectively. Both the Gompertz and third-order polynomial models yielded similarly adequate results for the body size of age 1 brown frogs, while the Janoschek model produced a similarly adequate result for the body size of age 2 brown frogs. The Brody and Janoschek models yielded the highest and lowest estimates of asymptotic weight, respectively, for the body weights of all frogs. The Kwl value of all frogs increased from 0.40 to 3.18. The K value of age 1 frogs decreased from 23.81 to 9.45 in the first four weeks. The K value of age 2 frogs remained close to 10. Graphically, a sigmoidal trend was observed for body weight and body size with increasing age. The results of this study will be useful not only for amphibian research but also for frog farming management strategies and decisions.
bibliographic citation: Tong et al. (2018) Modelling the growth of the brown frog (Rana dybowskii). PeerJ 6:e4587 https://doi.org/10.7717/peerj.4587
date submitted: 2017-11-22
date accepted: 2018-03-19
issued: 2018-05-16
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Tong
  given name: Qing
author list: Agent
  family name: Du
  given name: Xiao-peng
author list: Agent
  family name: Hu
  given name: Zong-fu
author list: Agent
  family name: Cui
  given name: Li-yong
author list: Agent
  family name: Wang
  given name: Hong-bin
doi: 10.7717/peerj.4587
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-05-16
copyright: © 2018 Tong et al.
attribution name: Tong et al.

Breast fibroblasts in both cancer and normal tissues induce phenotypic transformation of breast cancer stem cells: a preliminary study
type: item
type: AcademicArticle
description: Background Breast cancer stem cells (BCSCs) are associated with the invasion of breast cancer. In recent years, studies have demonstrated different phenotypes among BCSCs. Furthermore, BCSCs of diverse phenotypes are present at different tumour sites and different histological stages. Fibroblasts are involved in the phenotypic transformation of BCSCs. Cancer-associated fibroblasts (CAFs) participate in the induction of epithelial–mesenchymal transition, thereby promoting the acquisition of stem cell characteristics, but little is known about the role of normal fibroblasts (NFs) in the phenotypic transformation of BCSCs or about the effect of CAFs and NFs on BCSC phenotypes. Methods A total of six pairs of primary CAFs and NFs were isolated from surgical samples of breast cancer patients and subjected to morphological, immunohistochemical, cell invasion and proteomics analyses. After establishing a cell culture system with conditioned medium from CAFs and NFs, we used the mammosphere formation assay to explore the effect of CAFs and NFs on the self-renewal ability of BCSCs. The effect of CAFs and NFs on the phenotypic differentiation of BCSCs was further analysed by flow cytometry and immunofluorescence. Results The isolated CAFs and NFs did not show significant differences in cell morphology or alpha-smooth muscle actin (α-SMA) expression, but cell invasion and proteomics analyses demonstrated heterogeneity among these fibroblasts. Both CAFs and NFs could promote the generation of BCSCs, but CAFs displayed a greater ability than NFs in promoting mammosphere formation. Conditioned medium from CAFs increased the proportion of aldehyde dehydrogenase-1 positive (ALDH1+) BCSCs, but conditioned medium from NFs was more likely to promote the generation of CD44+CD24− BCSCs from MCF-7 cells. Discussion This study validated the heterogeneity among CAFs and NFs and expanded on the conclusion that fibroblasts promote the generation of cancer stem cells. Our results particularly…
format: application/pdf
format: text/html
creator: Bixiao Wang
creator: Chunfang Xi
creator: Mingwei Liu
creator: Haichen Sun
creator: Shuang Liu
creator: Lei Song
creator: Hua Kang
subject: Cell Biology
subject: Oncology
description: doi:10.7717/peerj.4805
publisher: PeerJ Inc.
rights: © 2018 Wang et al.
abstract: Background Breast cancer stem cells (BCSCs) are associated with the invasion of breast cancer. In recent years, studies have demonstrated different phenotypes among BCSCs. Furthermore, BCSCs of diverse phenotypes are present at different tumour sites and different histological stages. Fibroblasts are involved in the phenotypic transformation of BCSCs. Cancer-associated fibroblasts (CAFs) participate in the induction of epithelial–mesenchymal transition, thereby promoting the acquisition of stem cell characteristics, but little is known about the role of normal fibroblasts (NFs) in the phenotypic transformation of BCSCs or about the effect of CAFs and NFs on BCSC phenotypes. Methods A total of six pairs of primary CAFs and NFs were isolated from surgical samples of breast cancer patients and subjected to morphological, immunohistochemical, cell invasion and proteomics analyses. After establishing a cell culture system with conditioned medium from CAFs and NFs, we used the mammosphere formation assay to explore the effect of CAFs and NFs on the self-renewal ability of BCSCs. The effect of CAFs and NFs on the phenotypic differentiation of BCSCs was further analysed by flow cytometry and immunofluorescence. Results The isolated CAFs and NFs did not show significant differences in cell morphology or alpha-smooth muscle actin (α-SMA) expression, but cell invasion and proteomics analyses demonstrated heterogeneity among these fibroblasts. Both CAFs and NFs could promote the generation of BCSCs, but CAFs displayed a greater ability than NFs in promoting mammosphere formation. Conditioned medium from CAFs increased the proportion of aldehyde dehydrogenase-1 positive (ALDH1+) BCSCs, but conditioned medium from NFs was more likely to promote the generation of CD44+CD24− BCSCs from MCF-7 cells. Discussion This study validated the heterogeneity among CAFs and NFs and expanded on the conclusion that fibroblasts promote the generation of cancer stem cells. Our results particularly…
bibliographic citation: Wang et al. (2018) Breast fibroblasts in both cancer and normal tissues induce phenotypic transformation of breast cancer stem cells: a preliminary study. PeerJ 6:e4805 https://doi.org/10.7717/peerj.4805
date submitted: 2017-12-15
date accepted: 2018-04-29
issued: 2018-05-15
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Wang
  given name: Bixiao
author list: Agent
  family name: Xi
  given name: Chunfang
author list: Agent
  family name: Liu
  given name: Mingwei
author list: Agent
  family name: Sun
  given name: Haichen
author list: Agent
  family name: Liu
  given name: Shuang
author list: Agent
  family name: Song
  given name: Lei
author list: Agent
  family name: Kang
  given name: Hua
doi: 10.7717/peerj.4805
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-05-15
copyright: © 2018 Wang et al.
attribution name: Wang et al.

Latent profiles of elite Malaysian athletes’ use of psychological skills and techniques and relations with mental toughness
type: item
type: AcademicArticle
description: Background The majority of past work on athletes’ use of psychological skills and techniques (PSTs) has adopted a variable-centered approach in which the statistical relations among study variables are averaged across a sample. However, variable-centered-analyses exclude the possibility that PSTs may be used in tandem or combined in different ways across practice and competition settings. With this empirical gap in mind, the purposes of this study were to identify the number and type of profiles of elite athletes’ use of PSTs, and examine differences between these clusters in terms of their self-reported mental toughness. Methods In this cross-sectional survey study, 285 Malaysian elite athletes (170 males, 115 females) aged 15–44 years (M = 18.89, SD = 4.49) completed measures of various PSTs and mental toughness. Latent profile analysis was employed to determine the type and number of profiles that best represent athletes’ reports of their use of PSTs in practice and competition settings, and examine differences between these classes in terms of self-reported mental toughness. Results Our results revealed three profiles (low, moderate, high use) in both practice and competition settings that were distinguished primarily according to quantitative differences in the absolute levels of reported use across most of the PSTs assessed in practice and competition settings, which in turn, were differentially related with mental toughness. Specifically, higher use of PSTs was associated with higher levels of mental toughness. Conclusion This study provides one of the first analyses of the different configurations of athletes’ use of PSTs that typify unique subgroups of performers. An important next step is to examine the longitudinal (in) stability of such classes and therefore provide insight into the temporal dynamics of different configurations of athletes’ use of PSTs.
format: application/pdf
format: text/html
creator: Vellapandian Ponnusamy
creator: Robin L.J. Lines
creator: Chun-Qing Zhang
creator: Daniel F. Gucciardi
subject: Kinesiology
subject: Psychiatry and Psychology
description: doi:10.7717/peerj.4778
publisher: PeerJ Inc.
rights: © 2018 Ponnusamy et al.
abstract: Background The majority of past work on athletes’ use of psychological skills and techniques (PSTs) has adopted a variable-centered approach in which the statistical relations among study variables are averaged across a sample. However, variable-centered-analyses exclude the possibility that PSTs may be used in tandem or combined in different ways across practice and competition settings. With this empirical gap in mind, the purposes of this study were to identify the number and type of profiles of elite athletes’ use of PSTs, and examine differences between these clusters in terms of their self-reported mental toughness. Methods In this cross-sectional survey study, 285 Malaysian elite athletes (170 males, 115 females) aged 15–44 years (M = 18.89, SD = 4.49) completed measures of various PSTs and mental toughness. Latent profile analysis was employed to determine the type and number of profiles that best represent athletes’ reports of their use of PSTs in practice and competition settings, and examine differences between these classes in terms of self-reported mental toughness. Results Our results revealed three profiles (low, moderate, high use) in both practice and competition settings that were distinguished primarily according to quantitative differences in the absolute levels of reported use across most of the PSTs assessed in practice and competition settings, which in turn, were differentially related with mental toughness. Specifically, higher use of PSTs was associated with higher levels of mental toughness. Conclusion This study provides one of the first analyses of the different configurations of athletes’ use of PSTs that typify unique subgroups of performers. An important next step is to examine the longitudinal (in) stability of such classes and therefore provide insight into the temporal dynamics of different configurations of athletes’ use of PSTs.
bibliographic citation: Ponnusamy et al. (2018) Latent profiles of elite Malaysian athletes’ use of psychological skills and techniques and relations with mental toughness. PeerJ 6:e4778 https://doi.org/10.7717/peerj.4778
date submitted: 2018-02-12
date accepted: 2018-04-26
issued: 2018-05-15
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Ponnusamy
  given name: Vellapandian
author list: Agent
  family name: Lines
  given name: Robin L.J.
author list: Agent
  family name: Zhang
  given name: Chun-Qing
author list: Agent
  family name: Gucciardi
  given name: Daniel F.
doi: 10.7717/peerj.4778
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-05-15
copyright: © 2018 Ponnusamy et al.
attribution name: Ponnusamy et al.

PeerJ
type: Periodical
uri: PeerJ
issn: 2167-8359