PeerJ
type: channel
link: https://peerj.com/articles/
description: Articles published in PeerJ
publisher: PeerJ Inc.
publication name: PeerJ
issn: 2167-8359
items: Founder effects drive the genetic structure of passively dispersed aquatic invertebrates
items: Four tyrosine residues of the rice immune receptor XA21 are not required for interaction with the co-receptor OsSERK2 or resistance to Xanthomonas oryzae pv. oryzae
items: A tuber mustard AP2/ERF transcription factor gene, BjABR1, functioning in abscisic acid and abiotic stress responses, and evolutionary trajectory of the ABR1 homologous genes in Brassica species
items: Changes in intentional binding effect during a novel perceptual-motor task
items: Combining ultraconserved elements and mtDNA data to uncover lineage diversity in a Mexican highland frog (Sarcohyla; Hylidae)
items: Effects of crude oil on survival and development in embryonated eggs in Callinectes sapidus Rathbun, 1896 (Decapoda, Portunidae)
items: Stress among on-duty firefighters: an ambulatory assessment study
items: Plant-derived chimeric antibodies inhibit the invasion of human fibroblasts by Toxoplasma gondii
items: Behavior problems and personality in Korean high school students
items: Effects of gelsemine on oxidative stress and DNA damage responses of Tetrahymena thermophila

Founder effects drive the genetic structure of passively dispersed aquatic invertebrates
type: item
type: AcademicArticle
description: Populations of passively dispersed organisms in continental aquatic habitats typically show high levels of neutral genetic differentiation despite their high dispersal capabilities. Several evolutionary factors, including founder events, local adaptation, and life cycle features such as high population growth rates and the presence of propagule banks, have been proposed to be responsible for this paradox. Here, we have modeled the colonization process to assess the impact of migration rate, population growth rate, population size, local adaptation and life-cycle features on the population genetic structure in these organisms. Our simulations show that the strongest effect on population structure are persistent founder effects, resulting from the interaction of a few population founders, high population growth rates, large population sizes and the presence of diapausing egg banks. In contrast, the role of local adaptation, genetic hitchhiking and migration is limited to small populations in these organisms. Our results indicate that local adaptation could have different impact on genetic structure in different groups of zooplankters.
format: application/pdf
format: text/html
creator: Javier Montero-Pau
creator: Africa Gómez
creator: Manuel Serra
subject: Ecology
subject: Evolutionary Studies
subject: Genetics
subject: Freshwater Biology
description: doi:10.7717/peerj.6094
publisher: PeerJ Inc.
rights: © 2018 Montero-Pau et al.
abstract: Populations of passively dispersed organisms in continental aquatic habitats typically show high levels of neutral genetic differentiation despite their high dispersal capabilities. Several evolutionary factors, including founder events, local adaptation, and life cycle features such as high population growth rates and the presence of propagule banks, have been proposed to be responsible for this paradox. Here, we have modeled the colonization process to assess the impact of migration rate, population growth rate, population size, local adaptation and life-cycle features on the population genetic structure in these organisms. Our simulations show that the strongest effect on population structure are persistent founder effects, resulting from the interaction of a few population founders, high population growth rates, large population sizes and the presence of diapausing egg banks. In contrast, the role of local adaptation, genetic hitchhiking and migration is limited to small populations in these organisms. Our results indicate that local adaptation could have different impact on genetic structure in different groups of zooplankters.
bibliographic citation: Montero-Pau et al. (2018) Founder effects drive the genetic structure of passively dispersed aquatic invertebrates. PeerJ 6:e6094 https://doi.org/10.7717/peerj.6094
date submitted: 2018-07-24
date accepted: 2018-11-10
issued: 2018-12-11
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Montero-Pau
  given name: Javier
author list: Agent
  family name: Gómez
  given name: Africa
author list: Agent
  family name: Serra
  given name: Manuel
doi: 10.7717/peerj.6094
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-12-11
copyright: ©2018 Montero-Pau et al.
attribution name: Montero-Pau et al.

Four tyrosine residues of the rice immune receptor XA21 are not required for interaction with the co-receptor OsSERK2 or resistance to Xanthomonas oryzae pv. oryzae
type: item
type: AcademicArticle
description: Tyrosine phosphorylation has emerged as an important regulator of plasma membrane-localized immune receptors activity. Here, we investigate the role of tyrosine phosphorylation in the regulation of rice XANTHOMONAS RESISTANCE 21 (XA21)-mediated immunity. We demonstrate that the juxtamembrane and kinase domain of Escherichia coli–expressed XA21 (XA21JK) autophosphorylates on tyrosine residues. Directed mutagenesis of four out of the nine tyrosine residues in XA21JK reduced autophosphorylation. These sites include Tyr698 in the juxtamembrane domain, and Tyr786, Tyr907, and Tyr909 in the kinase domain. Rice plants expressing XA21-GFP fusion proteins or proteins with these tyrosine residues individually mutated to phenylalanine (XA21YF-GFP), which prevents phosphorylation at these sites, maintain resistance to Xanthomonas oryzae pv. oryzae. In contrast, plants expressing phosphomimetic XA21 variants with tyrosine mutated to aspartate (XA21YD-GFP) were susceptible. In vitro purified XA21JKY698F, XA21JKY907F, and XA21JKY909F variants are catalytically active, whereas activity was not detected in XA21JKY768F and the four XA21JKYD variants. We previously demonstrated that interaction of XA21 with the co-receptor OsSERK2 is critical for biological function. Four of the XA21JKYF variants maintain interaction with OsSERK2 as well as the XA21 binding (XB) proteins XB3 and XB15 in yeast, suggesting that these four tyrosine residues are not required for their interaction. Taken together, these results suggest that XA21 is capable of tyrosine autophosphorylation, but the identified tyrosine residues are not required for activation of XA21-mediated immunity or interaction with predicted XA21 signaling proteins.
format: application/pdf
format: text/html
creator: Daniel F. Caddell
creator: Tong Wei
creator: Sweta Sharma
creator: Man-Ho Oh
creator: Chang-Jin Park
creator: Patrick Canlas
creator: Steven C. Huber
creator: Pamela C. Ronald
subject: Agricultural Science
subject: Molecular Biology
subject: Plant Science
description: doi:10.7717/peerj.6074
publisher: PeerJ Inc.
rights: © 2018 Caddell et al.
abstract: Tyrosine phosphorylation has emerged as an important regulator of plasma membrane-localized immune receptors activity. Here, we investigate the role of tyrosine phosphorylation in the regulation of rice XANTHOMONAS RESISTANCE 21 (XA21)-mediated immunity. We demonstrate that the juxtamembrane and kinase domain of Escherichia coli–expressed XA21 (XA21JK) autophosphorylates on tyrosine residues. Directed mutagenesis of four out of the nine tyrosine residues in XA21JK reduced autophosphorylation. These sites include Tyr698 in the juxtamembrane domain, and Tyr786, Tyr907, and Tyr909 in the kinase domain. Rice plants expressing XA21-GFP fusion proteins or proteins with these tyrosine residues individually mutated to phenylalanine (XA21YF-GFP), which prevents phosphorylation at these sites, maintain resistance to Xanthomonas oryzae pv. oryzae. In contrast, plants expressing phosphomimetic XA21 variants with tyrosine mutated to aspartate (XA21YD-GFP) were susceptible. In vitro purified XA21JKY698F, XA21JKY907F, and XA21JKY909F variants are catalytically active, whereas activity was not detected in XA21JKY768F and the four XA21JKYD variants. We previously demonstrated that interaction of XA21 with the co-receptor OsSERK2 is critical for biological function. Four of the XA21JKYF variants maintain interaction with OsSERK2 as well as the XA21 binding (XB) proteins XB3 and XB15 in yeast, suggesting that these four tyrosine residues are not required for their interaction. Taken together, these results suggest that XA21 is capable of tyrosine autophosphorylation, but the identified tyrosine residues are not required for activation of XA21-mediated immunity or interaction with predicted XA21 signaling proteins.
bibliographic citation: Caddell et al. (2018) Four tyrosine residues of the rice immune receptor XA21 are not required for interaction with the co-receptor OsSERK2 or resistance to Xanthomonas oryzae pv. oryzae. PeerJ 6:e6074 https://doi.org/10.7717/peerj.6074
date submitted: 2018-08-09
date accepted: 2018-11-02
issued: 2018-12-11
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Caddell
  given name: Daniel F.
author list: Agent
  family name: Wei
  given name: Tong
author list: Agent
  family name: Sharma
  given name: Sweta
author list: Agent
  family name: Oh
  given name: Man-Ho
author list: Agent
  family name: Park
  given name: Chang-Jin
author list: Agent
  family name: Canlas
  given name: Patrick
author list: Agent
  family name: Huber
  given name: Steven C.
author list: Agent
  family name: Ronald
  given name: Pamela C.
doi: 10.7717/peerj.6074
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-12-11
copyright: © 2018 Caddell et al.
attribution name: Caddell et al.

A tuber mustard AP2/ERF transcription factor gene, BjABR1, functioning in abscisic acid and abiotic stress responses, and evolutionary trajectory of the ABR1 homologous genes in Brassica species
type: item
type: AcademicArticle
description: The AP2/ERF superfamily of transcription factors is one of the largest transcription factor families in plants and plays an important role in plant development processes and stress responses. In this study, BjABR1, an AP2/ERF superfamily gene, from tuber mustard (Brassica juncea var. tumida Tsen et Lee), sharing high amino acid sequence similarity with the AtABR1 (Arabidopsis thaliana AP2-like abscisic acid repressor 1) gene, were performed functional research, and the ABR1 homologous genes in Brassica species were identified and performed phylogenetic analysis. The promoter sequence of BjABR1 contained many phytohormone- and stress-related cis-elements; ABA (abscisic acid) and abiotic stresses can induce BjABR1 expression in tuber mustard; overexpression of BjABR1 in Arabidopsis can alleviate plant sensitivity to ABA and salt and osmotic stresses, and the alleviation may be due to changes in stress/ABA-induced gene expression. These results indicated that BjABR1 functions in ABA and abiotic stress responses. By BLAST searches against the genome database of five Brassica species (three diploids, B. rapa, B. nigra, and B. oleracea, and two allotetraploid, B. juncea and B. napus) using the protein sequence of AtABR1, 3, 3, 3, 6, and 5 ABR1 homologous genes in B. nigra, B. rapa, B. oleracea, B. juncea, and B. napus were identified, respectively, and they shared high sequence similarity. By sequence analysis, annotation mistakes of the protein-coding regions of two ABR1 homologous genes, GSBRNA2T00134741001 and BjuB007684, were found and corrected. Then, the evolution analysis of these ABR1 homologous genes showed that the ancestor of the three diploid species had three ABR1 homologous genes and each diploid inherited all the three genes from their ancestor; then, allotetraploid B. juncea inherited all the six genes from B. rapa and B. nigra with no gene lost, while allotetraploid B. napus inherited all the three genes from B. oleracea and two genes from B. rapa with on…
format: application/pdf
format: text/html
creator: Liuxin Xiang
creator: Chao Liu
creator: Jingzhi Luo
creator: Lin He
creator: Yushan Deng
creator: Jie Yuan
creator: Chaofeng Wu
creator: Yingfan Cai
subject: Bioinformatics
subject: Molecular Biology
subject: Plant Science
description: doi:10.7717/peerj.6071
publisher: PeerJ Inc.
rights: © 2018 Xiang et al.
abstract: The AP2/ERF superfamily of transcription factors is one of the largest transcription factor families in plants and plays an important role in plant development processes and stress responses. In this study, BjABR1, an AP2/ERF superfamily gene, from tuber mustard (Brassica juncea var. tumida Tsen et Lee), sharing high amino acid sequence similarity with the AtABR1 (Arabidopsis thaliana AP2-like abscisic acid repressor 1) gene, were performed functional research, and the ABR1 homologous genes in Brassica species were identified and performed phylogenetic analysis. The promoter sequence of BjABR1 contained many phytohormone- and stress-related cis-elements; ABA (abscisic acid) and abiotic stresses can induce BjABR1 expression in tuber mustard; overexpression of BjABR1 in Arabidopsis can alleviate plant sensitivity to ABA and salt and osmotic stresses, and the alleviation may be due to changes in stress/ABA-induced gene expression. These results indicated that BjABR1 functions in ABA and abiotic stress responses. By BLAST searches against the genome database of five Brassica species (three diploids, B. rapa, B. nigra, and B. oleracea, and two allotetraploid, B. juncea and B. napus) using the protein sequence of AtABR1, 3, 3, 3, 6, and 5 ABR1 homologous genes in B. nigra, B. rapa, B. oleracea, B. juncea, and B. napus were identified, respectively, and they shared high sequence similarity. By sequence analysis, annotation mistakes of the protein-coding regions of two ABR1 homologous genes, GSBRNA2T00134741001 and BjuB007684, were found and corrected. Then, the evolution analysis of these ABR1 homologous genes showed that the ancestor of the three diploid species had three ABR1 homologous genes and each diploid inherited all the three genes from their ancestor; then, allotetraploid B. juncea inherited all the six genes from B. rapa and B. nigra with no gene lost, while allotetraploid B. napus inherited all the three genes from B. oleracea and two genes from B. rapa with on…
bibliographic citation: Xiang et al. (2018) A tuber mustard AP2/ERF transcription factor gene, BjABR1, functioning in abscisic acid and abiotic stress responses, and evolutionary trajectory of the ABR1 homologous genes in Brassica species. PeerJ 6:e6071 https://doi.org/10.7717/peerj.6071
date submitted: 2018-08-08
date accepted: 2018-11-02
issued: 2018-12-11
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Xiang
  given name: Liuxin
author list: Agent
  family name: Liu
  given name: Chao
author list: Agent
  family name: Luo
  given name: Jingzhi
author list: Agent
  family name: He
  given name: Lin
author list: Agent
  family name: Deng
  given name: Yushan
author list: Agent
  family name: Yuan
  given name: Jie
author list: Agent
  family name: Wu
  given name: Chaofeng
author list: Agent
  family name: Cai
  given name: Yingfan
doi: 10.7717/peerj.6071
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-12-11
copyright: © 2018 Xiang et al.
attribution name: Xiang et al.

Changes in intentional binding effect during a novel perceptual-motor task
type: item
type: AcademicArticle
description: Perceptual-motor learning describes the process of improving the smoothness and accuracy of movements. Intentional binding (IB) is a phenomenon whereby the length of time between performing a voluntary action and the production of a sensory outcome during perceptual-motor control is perceived as being shorter than the reality. How IB may change over the course of perceptual-motor learning, however, has not been explicitly investigated. Here, we developed a set of IB tasks during perceptual-motor learning. Participants were instructed to stop a circular moving object by key press when it reached the center of a target circle on the display screen. The distance between the center of the target circle and the center of the moving object was measured, and the error was used to approximate the perceptual-motor performance index. This task also included an additional exercise that was unrelated to the perceptual-motor task: after pressing the key, a sound was presented after a randomly chosen delay of 200, 500, or 700 ms and the participant had to estimate the delay interval. The difference between the estimated and actual delay was used as the IB value. A cluster analysis was then performed using the error values from the first and last task to group the participants based on their perceptual-motor performance. Participants showing a very small change in error value, and thus demonstrating a small effect of perceptual-motor learning, were classified into cluster 1. Those who exhibited a large decrease in error value from the first to the last set, and thus demonstrated a strong improvement in perceptual-motor performance, were classified into cluster 2. Those who exhibited perceptual-motor learning also showed improvements in the IB value. Our data suggest that IB is elevated when perceptual-motor learning occurs.
format: application/pdf
format: text/html
creator: Shu Morioka
creator: Kazuki Hayashida
creator: Yuki Nishi
creator: Sayaka Negi
creator: Michihiro Osumi
creator: Satoshi Nobusako
subject: Neuroscience
subject: Psychiatry and Psychology
description: doi:10.7717/peerj.6066
publisher: PeerJ Inc.
rights: © 2018 Morioka et al.
abstract: Perceptual-motor learning describes the process of improving the smoothness and accuracy of movements. Intentional binding (IB) is a phenomenon whereby the length of time between performing a voluntary action and the production of a sensory outcome during perceptual-motor control is perceived as being shorter than the reality. How IB may change over the course of perceptual-motor learning, however, has not been explicitly investigated. Here, we developed a set of IB tasks during perceptual-motor learning. Participants were instructed to stop a circular moving object by key press when it reached the center of a target circle on the display screen. The distance between the center of the target circle and the center of the moving object was measured, and the error was used to approximate the perceptual-motor performance index. This task also included an additional exercise that was unrelated to the perceptual-motor task: after pressing the key, a sound was presented after a randomly chosen delay of 200, 500, or 700 ms and the participant had to estimate the delay interval. The difference between the estimated and actual delay was used as the IB value. A cluster analysis was then performed using the error values from the first and last task to group the participants based on their perceptual-motor performance. Participants showing a very small change in error value, and thus demonstrating a small effect of perceptual-motor learning, were classified into cluster 1. Those who exhibited a large decrease in error value from the first to the last set, and thus demonstrated a strong improvement in perceptual-motor performance, were classified into cluster 2. Those who exhibited perceptual-motor learning also showed improvements in the IB value. Our data suggest that IB is elevated when perceptual-motor learning occurs.
bibliographic citation: Morioka et al. (2018) Changes in intentional binding effect during a novel perceptual-motor task. PeerJ 6:e6066 https://doi.org/10.7717/peerj.6066
date submitted: 2018-05-10
date accepted: 2018-11-05
issued: 2018-12-11
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Morioka
  given name: Shu
author list: Agent
  family name: Hayashida
  given name: Kazuki
author list: Agent
  family name: Nishi
  given name: Yuki
author list: Agent
  family name: Negi
  given name: Sayaka
author list: Agent
  family name: Nishi
  given name: Yuki
author list: Agent
  family name: Osumi
  given name: Michihiro
author list: Agent
  family name: Nobusako
  given name: Satoshi
doi: 10.7717/peerj.6066
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-12-11
copyright: © 2018 Morioka et al.
attribution name: Morioka et al.

Combining ultraconserved elements and mtDNA data to uncover lineage diversity in a Mexican highland frog (Sarcohyla; Hylidae)
type: item
type: AcademicArticle
description: Molecular studies have uncovered significant diversity in the Mexican Highlands, leading to the description of many new endemic species. DNA approaches to this kind of species discovery have included both mitochondrial DNA (mtDNA) sequencing and multilocus genomic methods. While these marker types have often been pitted against one another, there are benefits to deploying them together, as linked mtDNA data can provide the bridge between uncovering lineages through rigorous multilocus genomic analysis and identifying lineages through comparison to existing mtDNA databases. Here, we apply one class of multilocus genomic marker, ultraconserved elements (UCEs), and linked mtDNA data to a species complex of frogs (Sarcohyla bistincta, Hylidae) found in the Mexican Highlands. We generated data from 1,891 UCEs, which contained 1,742 informative SNPs for S. bistincta and closely related species and captured mitochondrial genomes for most samples. Genetic analyses based on both whole loci and SNPs agree there are six to seven distinct lineages within what is currently described as S. bistincta. Phylogenies from UCEs and mtDNA mostly agreed in their topologies, and the few differences suggested a more complex evolutionary history of the mtDNA marker. Our study demonstrates that the Mexican Highlands still hold substantial undescribed diversity, making their conservation a particularly urgent goal. The Trans-Mexican Volcanic Range stands out as a significant geographic feature in Sarcohyla and may have acted as a dispersal corridor for S. bistincta to spread to the north. Combining multilocus genomic data with linked mtDNA data is a useful approach for identifying potential new species and associating them with already described taxa, which will be especially important in groups with undescribed subadult phenotypes and cryptic species.
format: application/pdf
format: text/html
creator: Eugenia Zarza
creator: Elizabeth M. Connors
creator: James M. Maley
creator: Whitney L.E. Tsai
creator: Peter Heimes
creator: Moises Kaplan
creator: John E. McCormack
subject: Biodiversity
subject: Zoology
description: doi:10.7717/peerj.6045
publisher: PeerJ Inc.
rights: © 2018 Zarza et al.
abstract: Molecular studies have uncovered significant diversity in the Mexican Highlands, leading to the description of many new endemic species. DNA approaches to this kind of species discovery have included both mitochondrial DNA (mtDNA) sequencing and multilocus genomic methods. While these marker types have often been pitted against one another, there are benefits to deploying them together, as linked mtDNA data can provide the bridge between uncovering lineages through rigorous multilocus genomic analysis and identifying lineages through comparison to existing mtDNA databases. Here, we apply one class of multilocus genomic marker, ultraconserved elements (UCEs), and linked mtDNA data to a species complex of frogs (Sarcohyla bistincta, Hylidae) found in the Mexican Highlands. We generated data from 1,891 UCEs, which contained 1,742 informative SNPs for S. bistincta and closely related species and captured mitochondrial genomes for most samples. Genetic analyses based on both whole loci and SNPs agree there are six to seven distinct lineages within what is currently described as S. bistincta. Phylogenies from UCEs and mtDNA mostly agreed in their topologies, and the few differences suggested a more complex evolutionary history of the mtDNA marker. Our study demonstrates that the Mexican Highlands still hold substantial undescribed diversity, making their conservation a particularly urgent goal. The Trans-Mexican Volcanic Range stands out as a significant geographic feature in Sarcohyla and may have acted as a dispersal corridor for S. bistincta to spread to the north. Combining multilocus genomic data with linked mtDNA data is a useful approach for identifying potential new species and associating them with already described taxa, which will be especially important in groups with undescribed subadult phenotypes and cryptic species.
bibliographic citation: Zarza et al. (2018) Combining ultraconserved elements and mtDNA data to uncover lineage diversity in a Mexican highland frog (Sarcohyla; Hylidae). PeerJ 6:e6045 https://doi.org/10.7717/peerj.6045
date submitted: 2018-03-28
date accepted: 2018-10-31
issued: 2018-12-11
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Zarza
  given name: Eugenia
author list: Agent
  family name: Connors
  given name: Elizabeth M.
author list: Agent
  family name: Maley
  given name: James M.
author list: Agent
  family name: Tsai
  given name: Whitney L.E.
author list: Agent
  family name: Heimes
  given name: Peter
author list: Agent
  family name: Kaplan
  given name: Moises
author list: Agent
  family name: McCormack
  given name: John E.
doi: 10.7717/peerj.6045
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-12-11
copyright: ©2018 Zarza et al.
attribution name: Zarza et al.

Effects of crude oil on survival and development in embryonated eggs in Callinectes sapidus Rathbun, 1896 (Decapoda, Portunidae)
type: item
type: AcademicArticle
description: Blue crabs, Callinectes sapidus Rathbun, 1896, are ubiquitous along the Atlantic and Gulf coasts of the USA. These organisms play an integral role in the ecosystems of the Gulf of Mexico (GOM), where not only are they a keystone species, but are also socioeconomically important. The survival of embryonated eggs is necessary to ensure adequate recruitment into the next generation. Because the 2010 Deepwater Horizon oil spill (DWH) occurred during the peak of the blue crab spawning season, the incident likely impacted blue crab embryos. In order to assess the effect of oil on embryonic growth and development, we collected embryonated eggs from seven different female blue crabs from the GOM throughout the spawning season and exposed them to an oil concentration of 500 ppb (the approximate concentration of oil at the surface water near the site of the Deepwater Horizon oil rig). Exposure to oil at this concentration caused a significantly larger proportion of prezoeae vs. zoeae to hatch from embryonated eggs in experiments lasting longer than 4 days. Exposure to oil did not significantly affect overall survival or development rate. The prezoeal stage is a little-studied stage of blue crab development. Though it may or may not be a normal stage of development, this stage has been found to occur in suboptimal conditions and has lower survival than zoeal stages. The larger proportion of prezoeae following prolonged exposure to oil thus indicates that crude oil at concentrations likely to be experienced by crabs after the DWH spill negatively impacted the development of blue crab embryos. In addition to providing insight into the effects of the DWH, this study sheds light on embryonic development in blue crabs, a critical, but poorly investigated phase of this important species’ life cycle.
format: application/pdf
format: text/html
creator: Kelsie L. Kelly
creator: Caz M. Taylor
subject: Developmental Biology
subject: Marine Biology
subject: Toxicology
subject: Ecotoxicology
subject: Environmental Impacts
description: doi:10.7717/peerj.5985
publisher: PeerJ Inc.
rights: © 2018 Kelly and Taylor
abstract: Blue crabs, Callinectes sapidus Rathbun, 1896, are ubiquitous along the Atlantic and Gulf coasts of the USA. These organisms play an integral role in the ecosystems of the Gulf of Mexico (GOM), where not only are they a keystone species, but are also socioeconomically important. The survival of embryonated eggs is necessary to ensure adequate recruitment into the next generation. Because the 2010 Deepwater Horizon oil spill (DWH) occurred during the peak of the blue crab spawning season, the incident likely impacted blue crab embryos. In order to assess the effect of oil on embryonic growth and development, we collected embryonated eggs from seven different female blue crabs from the GOM throughout the spawning season and exposed them to an oil concentration of 500 ppb (the approximate concentration of oil at the surface water near the site of the Deepwater Horizon oil rig). Exposure to oil at this concentration caused a significantly larger proportion of prezoeae vs. zoeae to hatch from embryonated eggs in experiments lasting longer than 4 days. Exposure to oil did not significantly affect overall survival or development rate. The prezoeal stage is a little-studied stage of blue crab development. Though it may or may not be a normal stage of development, this stage has been found to occur in suboptimal conditions and has lower survival than zoeal stages. The larger proportion of prezoeae following prolonged exposure to oil thus indicates that crude oil at concentrations likely to be experienced by crabs after the DWH spill negatively impacted the development of blue crab embryos. In addition to providing insight into the effects of the DWH, this study sheds light on embryonic development in blue crabs, a critical, but poorly investigated phase of this important species’ life cycle.
bibliographic citation: Kelly et al. (2018) Effects of crude oil on survival and development in embryonated eggs in Callinectes sapidus Rathbun, 1896 (Decapoda, Portunidae). PeerJ 6:e5985 https://doi.org/10.7717/peerj.5985
date submitted: 2017-03-07
date accepted: 2018-10-22
issued: 2018-12-11
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Kelly
  given name: Kelsie L.
author list: Agent
  family name: Taylor
  given name: Caz M.
doi: 10.7717/peerj.5985
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-12-11
copyright: © 2018 Kelly and Taylor
attribution name: Kelly and Taylor

Stress among on-duty firefighters: an ambulatory assessment study
type: item
type: AcademicArticle
description: Background Stress at work has been broadly acknowledged as a worldwide problem and has been the focus of concern for many researchers. Firefighting, in particular, is frequently reported as a highly stressful occupation. In order to investigate firefighters’ occupational health in terms of stress events, perceptions, symptoms, and physiological reactions under real-world conditions, an ambulatory assessment protocol was developed. Methods Seventeen firefighters’ cardiac signal was continuously monitored during an average of three shifts within a working week with medical clinically certified equipment (VitalJacket®), which allows for continuous electrocardiogram (ECG) and actigraphy measurement. Psychological data were collected with a software application running on smartphones, collecting potential stressful events, stress symptoms, and stress appraisal. Results A total of 450.56 h of medical-quality ECG were collected, and heart rate variability (HRV) analysis was performed. Findings suggest that although ‘fire’ situations are more common, ‘accidents’ are more stressful. Additionally, firefighters showed high levels of physiological stress (based on AVNN and LF/HF HRV metrics) when compared to normative healthy population values that may not be diagnosed using merely self-reports. Discussion The proposed ambulatory study seems to be useful for the monitoring of stress levels and its potential impact on health of first responders. Additionally, it could also be an important tool for the design and implementation of efficient interventions and informed management resolutions in real time. Potential applications of this research include the development of quantified occupational health (qOHealth) devices for real life monitoring of emergency personnel stress reactions.
format: application/pdf
format: text/html
creator: Susana Rodrigues
creator: Joana S. Paiva
creator: Duarte Dias
creator: João Paulo S. Cunha
subject: Bioengineering
subject: Psychiatry and Psychology
subject: Public Health
description: doi:10.7717/peerj.5967
publisher: PeerJ Inc.
rights: © 2018 Rodrigues et al.
abstract: Background Stress at work has been broadly acknowledged as a worldwide problem and has been the focus of concern for many researchers. Firefighting, in particular, is frequently reported as a highly stressful occupation. In order to investigate firefighters’ occupational health in terms of stress events, perceptions, symptoms, and physiological reactions under real-world conditions, an ambulatory assessment protocol was developed. Methods Seventeen firefighters’ cardiac signal was continuously monitored during an average of three shifts within a working week with medical clinically certified equipment (VitalJacket®), which allows for continuous electrocardiogram (ECG) and actigraphy measurement. Psychological data were collected with a software application running on smartphones, collecting potential stressful events, stress symptoms, and stress appraisal. Results A total of 450.56 h of medical-quality ECG were collected, and heart rate variability (HRV) analysis was performed. Findings suggest that although ‘fire’ situations are more common, ‘accidents’ are more stressful. Additionally, firefighters showed high levels of physiological stress (based on AVNN and LF/HF HRV metrics) when compared to normative healthy population values that may not be diagnosed using merely self-reports. Discussion The proposed ambulatory study seems to be useful for the monitoring of stress levels and its potential impact on health of first responders. Additionally, it could also be an important tool for the design and implementation of efficient interventions and informed management resolutions in real time. Potential applications of this research include the development of quantified occupational health (qOHealth) devices for real life monitoring of emergency personnel stress reactions.
bibliographic citation: Rodrigues et al. (2018) Stress among on-duty firefighters: an ambulatory assessment study. PeerJ 6:e5967 https://doi.org/10.7717/peerj.5967
date submitted: 2018-07-03
date accepted: 2018-10-19
issued: 2018-12-11
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Rodrigues
  given name: Susana
author list: Agent
  family name: Paiva
  given name: Joana S.
author list: Agent
  family name: Dias
  given name: Duarte
author list: Agent
  family name: Cunha
  given name: João Paulo S.
doi: 10.7717/peerj.5967
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-12-11
copyright: ©2018 Rodrigues et al.
attribution name: Rodrigues et al.

Plant-derived chimeric antibodies inhibit the invasion of human fibroblasts by Toxoplasma gondii
type: item
type: AcademicArticle
description: The parasite Toxoplasma gondii causes an opportunistic infection, that is, particularly severe in immunocompromised patients, infants, and neonates. Current antiparasitic drugs are teratogenic and cause hypersensitivity-based toxic side effects especially during prolonged treatment. Furthermore, the recent emergence of drug-resistant toxoplasmosis has reduced the therapeutic impact of such drugs. In an effort to develop recombinant antibodies as a therapeutic alternative, a panel of affinity-matured, T. gondii tachyzoite-specific single-chain variable fragment (scFv) antibodies was selected by phage display and bioinformatic analysis. Further affinity optimization was attempted by introducing point mutations at hotspots within light chain complementarity-determining region 2. This strategy yielded four mutated scFv sequences and a parental scFv that were used to produce five mouse–human chimeric IgGs in Nicotiana benthamiana plants, with yields of 33–72 mg/kg of plant tissue. Immunological analysis confirmed the specific binding of these plant-derived antibodies to T. gondii tachyzoites, and in vitro efficacy was demonstrated by their ability to inhibit the invasion of human fibroblasts and impair parasite infectivity. These novel recombinant antibodies could therefore be suitable for the development of plant-derived immunotherapeutic interventions against toxoplasmosis.
format: application/pdf
format: text/html
creator: Sherene Swee Yin Lim
creator: Kek Heng Chua
creator: Greta Nölke
creator: Holger Spiegel
creator: Wai Leong Goh
creator: Sek Chuen Chow
creator: Boon Pin Kee
creator: Rainer Fischer
creator: Stefan Schillberg
creator: Rofina Yasmin Othman
subject: Biotechnology
subject: Molecular Biology
subject: Parasitology
subject: Plant Science
subject: Immunology
description: doi:10.7717/peerj.5780
publisher: PeerJ Inc.
rights: © 2018 Lim et al.
abstract: The parasite Toxoplasma gondii causes an opportunistic infection, that is, particularly severe in immunocompromised patients, infants, and neonates. Current antiparasitic drugs are teratogenic and cause hypersensitivity-based toxic side effects especially during prolonged treatment. Furthermore, the recent emergence of drug-resistant toxoplasmosis has reduced the therapeutic impact of such drugs. In an effort to develop recombinant antibodies as a therapeutic alternative, a panel of affinity-matured, T. gondii tachyzoite-specific single-chain variable fragment (scFv) antibodies was selected by phage display and bioinformatic analysis. Further affinity optimization was attempted by introducing point mutations at hotspots within light chain complementarity-determining region 2. This strategy yielded four mutated scFv sequences and a parental scFv that were used to produce five mouse–human chimeric IgGs in Nicotiana benthamiana plants, with yields of 33–72 mg/kg of plant tissue. Immunological analysis confirmed the specific binding of these plant-derived antibodies to T. gondii tachyzoites, and in vitro efficacy was demonstrated by their ability to inhibit the invasion of human fibroblasts and impair parasite infectivity. These novel recombinant antibodies could therefore be suitable for the development of plant-derived immunotherapeutic interventions against toxoplasmosis.
bibliographic citation: Lim et al. (2018) Plant-derived chimeric antibodies inhibit the invasion of human fibroblasts by Toxoplasma gondii. PeerJ 6:e5780 https://doi.org/10.7717/peerj.5780
date submitted: 2017-06-14
date accepted: 2018-09-17
issued: 2018-12-11
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Lim
  given name: Sherene Swee Yin
author list: Agent
  family name: Chua
  given name: Kek Heng
author list: Agent
  family name: Nölke
  given name: Greta
author list: Agent
  family name: Spiegel
  given name: Holger
author list: Agent
  family name: Goh
  given name: Wai Leong
author list: Agent
  family name: Chow
  given name: Sek Chuen
author list: Agent
  family name: Kee
  given name: Boon Pin
author list: Agent
  family name: Fischer
  given name: Rainer
author list: Agent
  family name: Schillberg
  given name: Stefan
author list: Agent
  family name: Othman
  given name: Rofina Yasmin
doi: 10.7717/peerj.5780
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-12-11
copyright: © 2018 Lim et al.
attribution name: Lim et al.

Behavior problems and personality in Korean high school students
type: item
type: AcademicArticle
description: Introduction Extant studies have examined the effect of psychological characteristics on clinical features that define behavior problems. The purpose of this study was to analyze the effects of temperament and character as both individual factors and complex profiles on behavior problems in a community sample of adolescents. Methods Behavior problems and personality of 670 Korean high school students were measured with the Youth Self-Report (YSR) and Junior version of the Temperament and Character Inventory (JTCI). Stepwise regression analysis analyzed the effects of JTCI character and temperament traits on YSR Total, Internalizing and Externalizing subscale scores, and Profile Analysis examined differences of JTCI personality profiles among three latent YSR subscale profiles acquired from Latent Profile Analysis. Results Seven subscales of the JTCI explained 38% of the YSR total degree of behavior problems, and JTCI Novelty-Seeking and Harm-Avoidance were found to account for vulnerability while JTCI Reward-Dependence and Self-Directedness explained resilience to behavior problems. There were three distinct latent YSR profile groups based on nine YSR subscales, and low behavior problem group showed a resilient personality profile characterized by low Novelty-Seeking and Harm-Avoidance and high Reward-Dependence, Persistence, Self-Directedness and Cooperativeness while high behavior problem group exhibited a vulnerable personality profile of the opposite tendency. Discussion Temperament and character explained behavior problems of Korean high school students as both individual personality traits and a complex personality profile. The results and implications of this study were examined in regard to mental health of adolescents, and the importance of education in the development of mature personality are discussed.
format: application/pdf
format: text/html
creator: Soo Jin Lee
creator: Soo Hyun Park
creator: C Robert Cloninger
creator: Han Chae
subject: Pediatrics
subject: Psychiatry and Psychology
subject: Public Health
description: doi:10.7717/peerj.6106
publisher: PeerJ Inc.
rights: © 2018 Lee et al.
abstract: Introduction Extant studies have examined the effect of psychological characteristics on clinical features that define behavior problems. The purpose of this study was to analyze the effects of temperament and character as both individual factors and complex profiles on behavior problems in a community sample of adolescents. Methods Behavior problems and personality of 670 Korean high school students were measured with the Youth Self-Report (YSR) and Junior version of the Temperament and Character Inventory (JTCI). Stepwise regression analysis analyzed the effects of JTCI character and temperament traits on YSR Total, Internalizing and Externalizing subscale scores, and Profile Analysis examined differences of JTCI personality profiles among three latent YSR subscale profiles acquired from Latent Profile Analysis. Results Seven subscales of the JTCI explained 38% of the YSR total degree of behavior problems, and JTCI Novelty-Seeking and Harm-Avoidance were found to account for vulnerability while JTCI Reward-Dependence and Self-Directedness explained resilience to behavior problems. There were three distinct latent YSR profile groups based on nine YSR subscales, and low behavior problem group showed a resilient personality profile characterized by low Novelty-Seeking and Harm-Avoidance and high Reward-Dependence, Persistence, Self-Directedness and Cooperativeness while high behavior problem group exhibited a vulnerable personality profile of the opposite tendency. Discussion Temperament and character explained behavior problems of Korean high school students as both individual personality traits and a complex personality profile. The results and implications of this study were examined in regard to mental health of adolescents, and the importance of education in the development of mature personality are discussed.
bibliographic citation: Lee et al. (2018) Behavior problems and personality in Korean high school students. PeerJ 6:e6106 https://doi.org/10.7717/peerj.6106
date submitted: 2018-07-12
date accepted: 2018-11-14
issued: 2018-12-10
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Lee
  given name: Soo Jin
author list: Agent
  family name: Park
  given name: Soo Hyun
author list: Agent
  family name: Cloninger
  given name: C Robert
author list: Agent
  family name: Chae
  given name: Han
doi: 10.7717/peerj.6106
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-12-10
copyright: ©2018 Lee et al.
attribution name: Lee et al.

Effects of gelsemine on oxidative stress and DNA damage responses of Tetrahymena thermophila
type: item
type: AcademicArticle
description: Gelsemine is an important toxic substance extracted from Gelsemium elegans, which has a lot of biological functions in cells and organisms, but its toxicity has been rarely reported in Tetrahymena thermophila. In this study, we used the protozoan T. thermophila as an experimental model to investigate the potential toxicity-induced mechanism of gelsemine in the unicellular eukaryote. Our results clearly showed gelsemine inhibited T. thermophila growth in a dose-dependent manner. This exposure also resulted in oxidative stress on T. thermophila cells and antioxidant enzyme levels were significantly altered at high gelsemine levels (p < 0.05). Gelsemine produced a slight apoptotic effect at the highest (0.8 mg/mL) gelsemine level used here (p < 0.05). Furthermore, the toxin-induced DNA damage in a dose-dependent manner. The ultrastructural analysis also revealed mitophagic vacuoles at 0.4 and 0.8 mg/mL levels of gelsemine exposure. Moreover, expressions of oxidative stress-related and MAP kinase genes were significantly changed after exposure to 0.8 mg/mL level of gelsemine (p < 0.05). Altogether, our results clearly show that gelsemine from G. elegans can inhibit the growth via inducing oxidative stress and DNA damage in T. thermophila cells.
format: application/pdf
format: text/html
creator: Qiao Ye
creator: Yongyong Feng
creator: Zhenlu Wang
creator: Wenzhao Jiang
creator: Yuexin Qu
creator: Chaonan Zhang
creator: Aiguo Zhou
creator: Shaolin Xie
creator: Jixing Zou
subject: Microbiology
subject: Toxicology
subject: Zoology
description: doi:10.7717/peerj.6093
publisher: PeerJ Inc.
rights: © 2018 Ye et al.
abstract: Gelsemine is an important toxic substance extracted from Gelsemium elegans, which has a lot of biological functions in cells and organisms, but its toxicity has been rarely reported in Tetrahymena thermophila. In this study, we used the protozoan T. thermophila as an experimental model to investigate the potential toxicity-induced mechanism of gelsemine in the unicellular eukaryote. Our results clearly showed gelsemine inhibited T. thermophila growth in a dose-dependent manner. This exposure also resulted in oxidative stress on T. thermophila cells and antioxidant enzyme levels were significantly altered at high gelsemine levels (p < 0.05). Gelsemine produced a slight apoptotic effect at the highest (0.8 mg/mL) gelsemine level used here (p < 0.05). Furthermore, the toxin-induced DNA damage in a dose-dependent manner. The ultrastructural analysis also revealed mitophagic vacuoles at 0.4 and 0.8 mg/mL levels of gelsemine exposure. Moreover, expressions of oxidative stress-related and MAP kinase genes were significantly changed after exposure to 0.8 mg/mL level of gelsemine (p < 0.05). Altogether, our results clearly show that gelsemine from G. elegans can inhibit the growth via inducing oxidative stress and DNA damage in T. thermophila cells.
bibliographic citation: Ye et al. (2018) Effects of gelsemine on oxidative stress and DNA damage responses of Tetrahymena thermophila. PeerJ 6:e6093 https://doi.org/10.7717/peerj.6093
date submitted: 2018-06-06
date accepted: 2018-11-10
issued: 2018-12-10
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Ye
  given name: Qiao
author list: Agent
  family name: Feng
  given name: Yongyong
author list: Agent
  family name: Wang
  given name: Zhenlu
author list: Agent
  family name: Jiang
  given name: Wenzhao
author list: Agent
  family name: Qu
  given name: Yuexin
author list: Agent
  family name: Zhang
  given name: Chaonan
author list: Agent
  family name: Zhou
  given name: Aiguo
author list: Agent
  family name: Xie
  given name: Shaolin
author list: Agent
  family name: Zou
  given name: Jixing
doi: 10.7717/peerj.6093
volume: 6
issn: 2167-8359
publication name: PeerJ
publication date: 2018-12-10
copyright: © 2018 Ye et al.
attribution name: Ye et al.

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