PeerJ
type: channel
link: https://peerj.com/articles/
description: Articles published in PeerJ
publisher: PeerJ Inc.
publication name: PeerJ
issn: 2167-8359
items: Species turnover reveals hidden effects of decreasing nitrogen deposition in mountain hay meadows
items: Identification of special key genes for alcohol-related hepatocellular carcinoma through bioinformatic analysis
items: Digging for DNA at depth: rapid universal metabarcoding surveys (RUMS) as a tool to detect coral reef biodiversity across a depth gradient
items: Genetic alteration of histone lysine methyltransferases and their significance in renal cell carcinoma
items: Comprehensive analysis of lncRNA-associated competing endogenous RNA network in tongue squamous cell carcinoma
items: Quantitative color profiling of digital images with earth mover’s distance using the R package colordistance
items: Behavioral correlates of semi-zygodactyly in Ospreys (Pandion haliaetus) based on analysis of internet images
items: Low-carbohydrate diets differing in carbohydrate restriction improve cardiometabolic and anthropometric markers in healthy adults: A randomised clinical trial
items: Genome-wide identification and comparative evolutionary analysis of the Dof transcription factor family in physic nut and castor bean
items: Blood parasites infecting the Hoatzin (Opisthocomus hoazin), a unique neotropical folivorous bird

Species turnover reveals hidden effects of decreasing nitrogen deposition in mountain hay meadows
type: item
type: AcademicArticle
description: Nitrogen (N) deposition is a major threat to biodiversity in many habitats. The recent introduction of cleaner technologies in Switzerland has led to a reduction in the emissions of nitrogen oxides, with a consequent decrease in N deposition. We examined different drivers of plant community change, that is, N deposition, climate warming, and land-use change, in Swiss mountain hay meadows, using data from the Swiss biodiversity monitoring program. We compared indicator values of species that disappeared from or colonized a site (species turnover) with the indicator values of randomly chosen species from the same site. While oligotrophic plant species were more likely to colonize, compared to random expectation, we found only weak shifts in plant community composition. In particular, the average nutrient value of plant communities remained stable over time (2003–2017). We found the largest deviations from random expectation in the nutrient values of colonizing species, suggesting that N deposition or other factors that change the nutrient content of soils were important drivers of the species composition change over the last 15 years in Swiss mountain hay meadows. In addition, we observed an overall replacement of species with lower indicator values for temperature with species with higher values. Apparently, the community effects of the replacement of eutrophic species with oligotrophic species was outweighed by climate warming. Our results add to the increasing evidence that plant communities in changing environments may be relatively stable regarding average species richness or average indicator values, but that this apparent stability is often accompanied by a marked turnover of species.
format: application/pdf
format: text/html
creator: Tobias Roth
creator: Lukas Kohli
creator: Christoph Bühler
creator: Beat Rihm
creator: Reto Giulio Meuli
creator: Reto Meier
creator: Valentin Amrhein
subject: Biodiversity
subject: Ecology
subject: Plant Science
subject: Climate Change Biology
subject: Environmental Impacts
description: doi:10.7717/peerj.6347
publisher: PeerJ Inc.
rights: © 2019 Roth et al.
abstract: Nitrogen (N) deposition is a major threat to biodiversity in many habitats. The recent introduction of cleaner technologies in Switzerland has led to a reduction in the emissions of nitrogen oxides, with a consequent decrease in N deposition. We examined different drivers of plant community change, that is, N deposition, climate warming, and land-use change, in Swiss mountain hay meadows, using data from the Swiss biodiversity monitoring program. We compared indicator values of species that disappeared from or colonized a site (species turnover) with the indicator values of randomly chosen species from the same site. While oligotrophic plant species were more likely to colonize, compared to random expectation, we found only weak shifts in plant community composition. In particular, the average nutrient value of plant communities remained stable over time (2003–2017). We found the largest deviations from random expectation in the nutrient values of colonizing species, suggesting that N deposition or other factors that change the nutrient content of soils were important drivers of the species composition change over the last 15 years in Swiss mountain hay meadows. In addition, we observed an overall replacement of species with lower indicator values for temperature with species with higher values. Apparently, the community effects of the replacement of eutrophic species with oligotrophic species was outweighed by climate warming. Our results add to the increasing evidence that plant communities in changing environments may be relatively stable regarding average species richness or average indicator values, but that this apparent stability is often accompanied by a marked turnover of species.
bibliographic citation: Roth et al. (2019) Species turnover reveals hidden effects of decreasing nitrogen deposition in mountain hay meadows. PeerJ 7:e6347 https://doi.org/10.7717/peerj.6347
date submitted: 2018-09-14
date accepted: 2018-12-24
issued: 2019-02-06
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Roth
  given name: Tobias
author list: Agent
  family name: Kohli
  given name: Lukas
author list: Agent
  family name: Bühler
  given name: Christoph
author list: Agent
  family name: Rihm
  given name: Beat
author list: Agent
  family name: Meuli
  given name: Reto Giulio
author list: Agent
  family name: Meier
  given name: Reto
author list: Agent
  family name: Amrhein
  given name: Valentin
doi: 10.7717/peerj.6347
volume: 7
issn: 2167-8359
publication name: PeerJ
publication date: 2019-02-06
copyright: © 2019 Roth et al.
attribution name: Roth et al.

Identification of special key genes for alcohol-related hepatocellular carcinoma through bioinformatic analysis
type: item
type: AcademicArticle
description: Background Alcohol-related hepatocellular carcinoma (HCC) was reported to be diagnosed at a later stage, but the mechanism was unknown. This study aimed to identify special key genes (SKGs) during alcohol-related HCC development and progression. Methods The mRNA data of 369 HCC patients and the clinical information were downloaded from the Cancer Genome Atlas project (TCGA). The 310 patients with certain HCC-related risk factors were included for analysis and divided into seven groups according to the risk factors. Survival analyses were applied for the HCC patients of different groups. The patients with hepatitis B virus or hepatitis C virus infection only were combined into the HCC-V group for further analysis. The differentially expressed genes (DEGs) between the HCCs with alcohol consumption only (HCC-A) and HCC-V tumors were identified through limma package in R with cutoff criteria│log2 fold change (logFC)|>1.0 and p < 0.05. The DEGs between eight alcohol-related HCCs and their paired normal livers of GSE59259 from the Gene Expression Omnibus (GEO) were identified through GEO2R (a built-in tool in GEO database) with cutoff criteria |logFC|> 2.0 and adj.p < 0.05. The intersection of the two sets of DEGs was considered SKGs which were then investigated for their specificity through comparisons between HCC-A and other four HCC groups. The SKGs were analyzed for their correlations with HCC-A stage and grade and their prognostic power for HCC-A patients. The expressional differences of the SKGs in the HCCs in whole were also investigated through Gene Expression Profiling Interactive Analysis (GEPIA). The SKGs in HCC were validated through Oncomine database analysis. Results Pathological stage is an independent prognostic factor for HCC patients. HCC-A patients were diagnosed later than HCC patients with other risk factors. Ten SKGs were identified and nine of them were confirmed for their differences in paired samples of HCC-A patients. Three (SLC22A10, CD5L, and U…
format: application/pdf
format: text/html
creator: Xiuzhi Zhang
creator: Chunyan Kang
creator: Ningning Li
creator: Xiaoli Liu
creator: Jinzhong Zhang
creator: Fenglan Gao
creator: Liping Dai
subject: Bioinformatics
subject: Gastroenterology and Hepatology
subject: Global Health
subject: Oncology
description: doi:10.7717/peerj.6375
publisher: PeerJ Inc.
rights: © 2019 Zhang et al.
abstract: Background Alcohol-related hepatocellular carcinoma (HCC) was reported to be diagnosed at a later stage, but the mechanism was unknown. This study aimed to identify special key genes (SKGs) during alcohol-related HCC development and progression. Methods The mRNA data of 369 HCC patients and the clinical information were downloaded from the Cancer Genome Atlas project (TCGA). The 310 patients with certain HCC-related risk factors were included for analysis and divided into seven groups according to the risk factors. Survival analyses were applied for the HCC patients of different groups. The patients with hepatitis B virus or hepatitis C virus infection only were combined into the HCC-V group for further analysis. The differentially expressed genes (DEGs) between the HCCs with alcohol consumption only (HCC-A) and HCC-V tumors were identified through limma package in R with cutoff criteria│log2 fold change (logFC)|>1.0 and p < 0.05. The DEGs between eight alcohol-related HCCs and their paired normal livers of GSE59259 from the Gene Expression Omnibus (GEO) were identified through GEO2R (a built-in tool in GEO database) with cutoff criteria |logFC|> 2.0 and adj.p < 0.05. The intersection of the two sets of DEGs was considered SKGs which were then investigated for their specificity through comparisons between HCC-A and other four HCC groups. The SKGs were analyzed for their correlations with HCC-A stage and grade and their prognostic power for HCC-A patients. The expressional differences of the SKGs in the HCCs in whole were also investigated through Gene Expression Profiling Interactive Analysis (GEPIA). The SKGs in HCC were validated through Oncomine database analysis. Results Pathological stage is an independent prognostic factor for HCC patients. HCC-A patients were diagnosed later than HCC patients with other risk factors. Ten SKGs were identified and nine of them were confirmed for their differences in paired samples of HCC-A patients. Three (SLC22A10, CD5L, and U…
bibliographic citation: Zhang et al. (2019) Identification of special key genes for alcohol-related hepatocellular carcinoma through bioinformatic analysis. PeerJ 7:e6375 https://doi.org/10.7717/peerj.6375
date submitted: 2018-09-18
date accepted: 2018-12-31
issued: 2019-02-06
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Zhang
  given name: Xiuzhi
author list: Agent
  family name: Kang
  given name: Chunyan
author list: Agent
  family name: Li
  given name: Ningning
author list: Agent
  family name: Liu
  given name: Xiaoli
author list: Agent
  family name: Zhang
  given name: Jinzhong
author list: Agent
  family name: Gao
  given name: Fenglan
author list: Agent
  family name: Dai
  given name: Liping
doi: 10.7717/peerj.6375
volume: 7
issn: 2167-8359
publication name: PeerJ
publication date: 2019-02-06
copyright: © 2019 Zhang et al.
attribution name: Zhang et al.

Digging for DNA at depth: rapid universal metabarcoding surveys (RUMS) as a tool to detect coral reef biodiversity across a depth gradient
type: item
type: AcademicArticle
description: Background Effective biodiversity monitoring is fundamental in tracking changes in ecosystems as it relates to commercial, recreational, and conservation interests. Current approaches to survey coral reef ecosystems center on the use of indicator species and repeat surveying at specific sites. However, such approaches are often limited by the narrow snapshot of total marine biodiversity that they describe and are thus hindered in their ability to contribute to holistic ecosystem-based monitoring. In tandem, environmental DNA (eDNA) and next-generation sequencing metabarcoding methods provide a new opportunity to rapidly assess the presence of a broad spectrum of eukaryotic organisms within our oceans, ranging from microbes to macrofauna. Methods We here investigate the potential for rapid universal metabarcoding surveys (RUMS) of eDNA in sediment samples to provide snapshots of eukaryotic subtropical biodiversity along a depth gradient at two coral reefs in Okinawa, Japan based on 18S rRNA. Results Using 18S rRNA metabarcoding, we found that there were significant separations in eukaryotic community assemblages (at the family level) detected in sediments when compared across different depths ranging from 10 to 40 m (p = 0.001). Significant depth zonation was observed across operational taxonomic units assigned to the class Demospongiae (sponges), the most diverse class (contributing 81% of species) within the phylum Porifera; the oldest metazoan phylum on the planet. However, zonation was not observed across the class Anthozoa (i.e., anemones, stony corals, soft corals, and octocorals), suggesting that the former may serve as a better source of indicator species based on sampling over fine spatial scales and using this universal assay. Furthermore, despite their abundance on the examined coral reefs, we did not detect any octocoral DNA, which may be due to low cellular shedding rates, assay sensitivities, or primer biases. Discussion Overall, our pilot study demonst…
format: application/pdf
format: text/html
creator: Joseph D. DiBattista
creator: James D. Reimer
creator: Michael Stat
creator: Giovanni D. Masucci
creator: Piera Biondi
creator: Maarten De Brauwer
creator: Michael Bunce
subject: Biodiversity
subject: Marine Biology
description: doi:10.7717/peerj.6379
publisher: PeerJ Inc.
rights: © 2019 DiBattista et al.
abstract: Background Effective biodiversity monitoring is fundamental in tracking changes in ecosystems as it relates to commercial, recreational, and conservation interests. Current approaches to survey coral reef ecosystems center on the use of indicator species and repeat surveying at specific sites. However, such approaches are often limited by the narrow snapshot of total marine biodiversity that they describe and are thus hindered in their ability to contribute to holistic ecosystem-based monitoring. In tandem, environmental DNA (eDNA) and next-generation sequencing metabarcoding methods provide a new opportunity to rapidly assess the presence of a broad spectrum of eukaryotic organisms within our oceans, ranging from microbes to macrofauna. Methods We here investigate the potential for rapid universal metabarcoding surveys (RUMS) of eDNA in sediment samples to provide snapshots of eukaryotic subtropical biodiversity along a depth gradient at two coral reefs in Okinawa, Japan based on 18S rRNA. Results Using 18S rRNA metabarcoding, we found that there were significant separations in eukaryotic community assemblages (at the family level) detected in sediments when compared across different depths ranging from 10 to 40 m (p = 0.001). Significant depth zonation was observed across operational taxonomic units assigned to the class Demospongiae (sponges), the most diverse class (contributing 81% of species) within the phylum Porifera; the oldest metazoan phylum on the planet. However, zonation was not observed across the class Anthozoa (i.e., anemones, stony corals, soft corals, and octocorals), suggesting that the former may serve as a better source of indicator species based on sampling over fine spatial scales and using this universal assay. Furthermore, despite their abundance on the examined coral reefs, we did not detect any octocoral DNA, which may be due to low cellular shedding rates, assay sensitivities, or primer biases. Discussion Overall, our pilot study demonst…
bibliographic citation: DiBattista et al. (2019) Digging for DNA at depth: rapid universal metabarcoding surveys (RUMS) as a tool to detect coral reef biodiversity across a depth gradient. PeerJ 7:e6379 https://doi.org/10.7717/peerj.6379
date submitted: 2018-10-15
date accepted: 2018-12-24
issued: 2019-02-06
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: DiBattista
  given name: Joseph D.
author list: Agent
  family name: Reimer
  given name: James D.
author list: Agent
  family name: Stat
  given name: Michael
author list: Agent
  family name: Masucci
  given name: Giovanni D.
author list: Agent
  family name: Biondi
  given name: Piera
author list: Agent
  family name: De Brauwer
  given name: Maarten
author list: Agent
  family name: Bunce
  given name: Michael
doi: 10.7717/peerj.6379
volume: 7
issn: 2167-8359
publication name: PeerJ
publication date: 2019-02-06
copyright: © 2019 DiBattista et al.
attribution name: DiBattista et al.

Genetic alteration of histone lysine methyltransferases and their significance in renal cell carcinoma
type: item
type: AcademicArticle
description: Background Histone lysine methyltransferases (HMTs), a category of enzymes, play essential roles in regulating transcription, cellular differentiation, and chromatin construction. The genomic landscape and clinical significance of HMTs in renal cell carcinoma (RCC) remain uncovered. Methods We conducted an integrative analysis of 50 HMTs in RCC and discovered the internal relations among copy number alterations (CNAs), expressive abundance, mutations, and clinical outcome. Results We confirmed 12 HMTs with the highest frequency of genetic alterations, including seven HMTs with high-level amplification, two HMTs with somatic mutation, and three HMTs with putative homozygous deletion. Patterns of copy number and expression varied among different subtypes of RCC, including clear cell renal cell carcinoma, papillary cell carcinoma, and chromophobe renal carcinoma. Kaplan–Meier survival analysis and multivariate analysis identified that CNA or mRNA expression in some HMTs were significantly associated with shorter overall patient survival. Systematic analysis identified six HMTs (ASH1L, PRDM6, NSD1, EZH2, WHSC1L1, SETD2) which were dysregulated by genetic alterations as candidate therapeutic targets. Discussion In summary, our findings strongly evidenced that genetic alteration of HMTs may play an important role in generation and development of RCC, which lays a solid foundation for the mechanism for further research in the future.
format: application/pdf
format: text/html
creator: Libin Yan
creator: Yangjun Zhang
creator: Beichen Ding
creator: Hui Zhou
creator: Weimin Yao
creator: Hua Xu
subject: Genetics
subject: Oncology
subject: Urology
description: doi:10.7717/peerj.6396
publisher: PeerJ Inc.
rights: © 2019 Yan et al.
abstract: Background Histone lysine methyltransferases (HMTs), a category of enzymes, play essential roles in regulating transcription, cellular differentiation, and chromatin construction. The genomic landscape and clinical significance of HMTs in renal cell carcinoma (RCC) remain uncovered. Methods We conducted an integrative analysis of 50 HMTs in RCC and discovered the internal relations among copy number alterations (CNAs), expressive abundance, mutations, and clinical outcome. Results We confirmed 12 HMTs with the highest frequency of genetic alterations, including seven HMTs with high-level amplification, two HMTs with somatic mutation, and three HMTs with putative homozygous deletion. Patterns of copy number and expression varied among different subtypes of RCC, including clear cell renal cell carcinoma, papillary cell carcinoma, and chromophobe renal carcinoma. Kaplan–Meier survival analysis and multivariate analysis identified that CNA or mRNA expression in some HMTs were significantly associated with shorter overall patient survival. Systematic analysis identified six HMTs (ASH1L, PRDM6, NSD1, EZH2, WHSC1L1, SETD2) which were dysregulated by genetic alterations as candidate therapeutic targets. Discussion In summary, our findings strongly evidenced that genetic alteration of HMTs may play an important role in generation and development of RCC, which lays a solid foundation for the mechanism for further research in the future.
bibliographic citation: Yan et al. (2019) Genetic alteration of histone lysine methyltransferases and their significance in renal cell carcinoma. PeerJ 7:e6396 https://doi.org/10.7717/peerj.6396
date submitted: 2018-08-01
date accepted: 2019-01-05
issued: 2019-02-06
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Yan
  given name: Libin
author list: Agent
  family name: Zhang
  given name: Yangjun
author list: Agent
  family name: Ding
  given name: Beichen
author list: Agent
  family name: Zhou
  given name: Hui
author list: Agent
  family name: Yao
  given name: Weimin
author list: Agent
  family name: Xu
  given name: Hua
doi: 10.7717/peerj.6396
volume: 7
issn: 2167-8359
publication name: PeerJ
publication date: 2019-02-06
copyright: © 2019 Yan et al.
attribution name: Yan et al.

Comprehensive analysis of lncRNA-associated competing endogenous RNA network in tongue squamous cell carcinoma
type: item
type: AcademicArticle
description: Background Increasing evidence has demonstrated that long non-coding RNAs (lncRNAs) play an important role in the competitive endogenous RNA (ceRNA) networks in that they regulate protein-coding gene expression by sponging microRNAs (miRNAs). However, the understanding of the ceRNA network in tongue squamous cell carcinoma (TSCC) remains limited. Methods Expression profile data regarding mRNAs, miRNAs and lncRNAs as well as clinical information on 122 TSCC tissues and 15 normal controls from The Cancer Genome Atlas (TCGA) database were collected. We used the edgR package to identify differentially expressed mRNAs (DEmRNAs), lncRNAs (DElncRNAs) and miRNAs (DEmiRNAs) between TSCC samples and normal samples. In order to explore the functions of DEmRNAs, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was performed. Subsequently, a ceRNA network was established based on the identified DElncRNAs–DEmiRNAs and DEmiRNAs–DEmRNAs interactions. The RNAs within the ceRNA network were analyzed for their correlation with overall disease survival. Finally, lncRNAs were specifically analyzed for their correlation with clinical features in the included TSCC patient samples. Results A total of 1867 mRNAs, 828 lncRNAs and 81 miRNAs were identified as differentially expressed in TSCC tissues (—log 2fold change— ≥ 2; adjusted P value <0.01). The resulting ceRNA network included 16 mRNAs, 56 lncRNAs and 6 miRNAs. Ten out of the 56 lncRNAs were found to be associated with the overall survival in TSCC patients (P < 0.05); 10 lncRNAs were correlated with TSCC progression (P < 0.05). Conclusion Our study deepens the understanding of ceRNA network regulatory mechanisms in TSCC. Furthermore, we identified ten lncRNAs (PART1, LINC00261, AL163952.1, C2orf48, FAM87A, LINC00052, LINC00472, STEAP3-AS1, TSPEAR-AS1 and ERVH48-1) as novel, potential prognostic biomarkers and therapeutic targets for TSCC.
format: application/pdf
format: text/html
creator: Shusen Zhang
creator: Ruoyan Cao
creator: Qiulan Li
creator: Mianfeng Yao
creator: Yu Chen
creator: Hongbo Zhou
subject: Bioinformatics
subject: Dentistry
subject: Oncology
description: doi:10.7717/peerj.6397
publisher: PeerJ Inc.
rights: © 2019 Zhang et al.
abstract: Background Increasing evidence has demonstrated that long non-coding RNAs (lncRNAs) play an important role in the competitive endogenous RNA (ceRNA) networks in that they regulate protein-coding gene expression by sponging microRNAs (miRNAs). However, the understanding of the ceRNA network in tongue squamous cell carcinoma (TSCC) remains limited. Methods Expression profile data regarding mRNAs, miRNAs and lncRNAs as well as clinical information on 122 TSCC tissues and 15 normal controls from The Cancer Genome Atlas (TCGA) database were collected. We used the edgR package to identify differentially expressed mRNAs (DEmRNAs), lncRNAs (DElncRNAs) and miRNAs (DEmiRNAs) between TSCC samples and normal samples. In order to explore the functions of DEmRNAs, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was performed. Subsequently, a ceRNA network was established based on the identified DElncRNAs–DEmiRNAs and DEmiRNAs–DEmRNAs interactions. The RNAs within the ceRNA network were analyzed for their correlation with overall disease survival. Finally, lncRNAs were specifically analyzed for their correlation with clinical features in the included TSCC patient samples. Results A total of 1867 mRNAs, 828 lncRNAs and 81 miRNAs were identified as differentially expressed in TSCC tissues (—log 2fold change— ≥ 2; adjusted P value <0.01). The resulting ceRNA network included 16 mRNAs, 56 lncRNAs and 6 miRNAs. Ten out of the 56 lncRNAs were found to be associated with the overall survival in TSCC patients (P < 0.05); 10 lncRNAs were correlated with TSCC progression (P < 0.05). Conclusion Our study deepens the understanding of ceRNA network regulatory mechanisms in TSCC. Furthermore, we identified ten lncRNAs (PART1, LINC00261, AL163952.1, C2orf48, FAM87A, LINC00052, LINC00472, STEAP3-AS1, TSPEAR-AS1 and ERVH48-1) as novel, potential prognostic biomarkers and therapeutic targets for TSCC.
bibliographic citation: Zhang et al. (2019) Comprehensive analysis of lncRNA-associated competing endogenous RNA network in tongue squamous cell carcinoma. PeerJ 7:e6397 https://doi.org/10.7717/peerj.6397
date submitted: 2018-10-03
date accepted: 2019-01-07
issued: 2019-02-06
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Zhang
  given name: Shusen
author list: Agent
  family name: Cao
  given name: Ruoyan
author list: Agent
  family name: Li
  given name: Qiulan
author list: Agent
  family name: Yao
  given name: Mianfeng
author list: Agent
  family name: Chen
  given name: Yu
author list: Agent
  family name: Zhou
  given name: Hongbo
doi: 10.7717/peerj.6397
volume: 7
issn: 2167-8359
publication name: PeerJ
publication date: 2019-02-06
copyright: ©2019 Zhang et al.
attribution name: Zhang et al.

Quantitative color profiling of digital images with earth mover’s distance using the R package colordistance
type: item
type: AcademicArticle
description: Biological color may be adaptive or incidental, seasonal or permanent, species- or population-specific, or modified for breeding, defense or camouflage. Although color is a hugely informative aspect of biology, quantitative color comparisons are notoriously difficult. Color comparison is limited by categorization methods, with available tools requiring either subjective classifications, or expensive equipment, software, and expertise. We present an R package for processing images of organisms (or other objects) in order to quantify color profiles, gather color trait data, and compare color palettes on the basis of color similarity and amount. The package treats image pixels as 3D coordinates in a “color space,” producing a multidimensional color histogram for each image. Pairwise distances between histograms are computed using earth mover’s distance, a technique borrowed from computer vision, that compares histograms using transportation costs. Users choose a color space, parameters for generating color histograms, and a pairwise comparison method to produce a color distance matrix for a set of images. The package is intended as a more rigorous alternative to subjective, manual digital image analyses, not as a replacement for more advanced techniques that rely on detailed spectrophotometry methods unavailable to many users. Here, we outline the basic functions of colordistance, provide guidelines for the available color spaces and quantification methods, and compare this toolkit with other available methods. The tools presented for quantitative color analysis may be applied to a broad range of questions in biology and other disciplines.
format: application/pdf
format: text/html
creator: Hannah I. Weller
creator: Mark W. Westneat
subject: Biodiversity
subject: Evolutionary Studies
subject: Statistics
description: doi:10.7717/peerj.6398
publisher: PeerJ Inc.
rights: © 2019 Weller and Westneat
abstract: Biological color may be adaptive or incidental, seasonal or permanent, species- or population-specific, or modified for breeding, defense or camouflage. Although color is a hugely informative aspect of biology, quantitative color comparisons are notoriously difficult. Color comparison is limited by categorization methods, with available tools requiring either subjective classifications, or expensive equipment, software, and expertise. We present an R package for processing images of organisms (or other objects) in order to quantify color profiles, gather color trait data, and compare color palettes on the basis of color similarity and amount. The package treats image pixels as 3D coordinates in a “color space,” producing a multidimensional color histogram for each image. Pairwise distances between histograms are computed using earth mover’s distance, a technique borrowed from computer vision, that compares histograms using transportation costs. Users choose a color space, parameters for generating color histograms, and a pairwise comparison method to produce a color distance matrix for a set of images. The package is intended as a more rigorous alternative to subjective, manual digital image analyses, not as a replacement for more advanced techniques that rely on detailed spectrophotometry methods unavailable to many users. Here, we outline the basic functions of colordistance, provide guidelines for the available color spaces and quantification methods, and compare this toolkit with other available methods. The tools presented for quantitative color analysis may be applied to a broad range of questions in biology and other disciplines.
bibliographic citation: Weller et al. (2019) Quantitative color profiling of digital images with earth mover’s distance using the R package colordistance. PeerJ 7:e6398 https://doi.org/10.7717/peerj.6398
date submitted: 2018-02-05
date accepted: 2019-01-03
issued: 2019-02-06
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Weller
  given name: Hannah I.
author list: Agent
  family name: Westneat
  given name: Mark W.
doi: 10.7717/peerj.6398
volume: 7
issn: 2167-8359
publication name: PeerJ
publication date: 2019-02-06
copyright: © 2019 Weller and Westneat
attribution name: Weller and Westneat

Behavioral correlates of semi-zygodactyly in Ospreys (Pandion haliaetus) based on analysis of internet images
type: item
type: AcademicArticle
description: Ospreys are renowned for their fishing abilities, which have largely been attributed to their specialized talon morphology and semi-zygodactyly−the ability to rotate the fourth toe to accompany the first toe in opposition of toes II and III. Anecdotal observations indicate that zygodactyly in Ospreys is associated with prey capture, although to our knowledge this has not been rigorously tested. As a first pass toward understanding the functional significance of semi-zygodactyly in Ospreys, we scoured the internet for images of Osprey feet in a variety of circumstances. From these we cross-tabulated the number of times each of three toe configurations (anisodactylous, zygodactylous, and an intermediate condition between these) was associated with different grasping scenarios (e.g., grasping prey or perched), contact conditions (e.g., fish, other objects, or substrate), object sizes (relative to foot size), and grasping behaviors (e.g., using one or both feet). Our analysis confirms an association between zygodactyly and grasping behavior; the odds that an osprey exhibited zygodactyly while grasping objects in flight were 5.7 times greater than whilst perched. Furthermore, the odds of zygodactyly during single-foot grasps were 4.1 times greater when pictured grasping fish compared to other objects. These results suggest a functional association between predatory behavior and zygodactyly and has implications for the selective role of predatory performance in the evolution of zygodactyly more generally.
format: application/pdf
format: text/html
creator: Diego Sustaita
creator: Yuri Gloumakov
creator: Leah R. Tsang
creator: Aaron M. Dollar
subject: Animal Behavior
subject: Zoology
description: doi:10.7717/peerj.6243
publisher: PeerJ Inc.
rights: © 2019 Sustaita et al.
abstract: Ospreys are renowned for their fishing abilities, which have largely been attributed to their specialized talon morphology and semi-zygodactyly−the ability to rotate the fourth toe to accompany the first toe in opposition of toes II and III. Anecdotal observations indicate that zygodactyly in Ospreys is associated with prey capture, although to our knowledge this has not been rigorously tested. As a first pass toward understanding the functional significance of semi-zygodactyly in Ospreys, we scoured the internet for images of Osprey feet in a variety of circumstances. From these we cross-tabulated the number of times each of three toe configurations (anisodactylous, zygodactylous, and an intermediate condition between these) was associated with different grasping scenarios (e.g., grasping prey or perched), contact conditions (e.g., fish, other objects, or substrate), object sizes (relative to foot size), and grasping behaviors (e.g., using one or both feet). Our analysis confirms an association between zygodactyly and grasping behavior; the odds that an osprey exhibited zygodactyly while grasping objects in flight were 5.7 times greater than whilst perched. Furthermore, the odds of zygodactyly during single-foot grasps were 4.1 times greater when pictured grasping fish compared to other objects. These results suggest a functional association between predatory behavior and zygodactyly and has implications for the selective role of predatory performance in the evolution of zygodactyly more generally.
bibliographic citation: Sustaita et al. (2019) Behavioral correlates of semi-zygodactyly in Ospreys (Pandion haliaetus) based on analysis of internet images. PeerJ 7:e6243 https://doi.org/10.7717/peerj.6243
date submitted: 2018-07-15
date accepted: 2018-12-09
issued: 2019-02-05
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Sustaita
  given name: Diego
author list: Agent
  family name: Gloumakov
  given name: Yuri
author list: Agent
  family name: Tsang
  given name: Leah R.
author list: Agent
  family name: Dollar
  given name: Aaron M.
doi: 10.7717/peerj.6243
volume: 7
issn: 2167-8359
publication name: PeerJ
publication date: 2019-02-05
copyright: © 2019 Sustaita et al.
attribution name: Sustaita et al.

Low-carbohydrate diets differing in carbohydrate restriction improve cardiometabolic and anthropometric markers in healthy adults: A randomised clinical trial
type: item
type: AcademicArticle
description: Background Low-carbohydrate, high-fat (LCHF) diets are useful for treating a range of health conditions, but there is little research evaluating the degree of carbohydrate restriction on outcome measures. This study compares anthropometric and cardiometabolic outcomes between differing carbohydrate-restricted diets. Objective Our hypothesis was that moderate carbohydrate restriction is easier to maintain and more effective for improving cardiometabolic health markers than greater restriction. Design A total of 77 healthy participants were randomised to a very low-carbohydrate ketogenic diet (VLCKD), low-carbohydrate diet (LCD), or moderate-low carbohydrate diet (MCD), containing 5%, 15% and 25% total energy from carbohydrate, respectively, for 12-weeks. Anthropometric and metabolic health measures were taken at baseline and at 12 weeks. Using ANOVA, both within and between-group outcomes were analysed. Results Of 77 participants, 39 (51%) completed the study. In these completers overall, significant reductions in weight and body mass index occurred ((mean change) 3.7 kg/m2; 95% confidence limits (CL): 3.8, 1.8), along with increases in high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, (0.49 mmol/L; 95% CL; 0.06, 0.92; p = 0.03), and total cholesterol concentrations (0.11 mmol/L; 95% CL; 0.00, 0.23; p = 0.05). Triglyceride (TG) levels were reduced by 0.12 mmol/L (95% CL; −0.20, 0.02; p = 0.02). No significant changes occurred between groups. The largest improvements in high density lipoprotein cholesterol (HDL-c) and TG and anthropometric changes occurred for the VLCKD group. Conclusions Low-carbohydrate, high-fat diets have a positive effect on markers of health. Adherence to the allocation of carbohydrate was more easily achieved in MCD, and LCD groups compared to VLCKD and there were comparable improvements in weight loss and waist circumference and greater improvements in HDL-c and TG with greater carbohydrate restriction.
format: application/pdf
format: text/html
creator: Cliff J. d. C. Harvey
creator: Grant M. Schofield
creator: Caryn Zinn
creator: Simon J. Thornley
creator: Catherine Crofts
creator: Fabrice L. R. Merien
subject: Nutrition
subject: Public Health
subject: Metabolic Sciences
description: doi:10.7717/peerj.6273
publisher: PeerJ Inc.
rights: © 2019 Harvey et al.
abstract: Background Low-carbohydrate, high-fat (LCHF) diets are useful for treating a range of health conditions, but there is little research evaluating the degree of carbohydrate restriction on outcome measures. This study compares anthropometric and cardiometabolic outcomes between differing carbohydrate-restricted diets. Objective Our hypothesis was that moderate carbohydrate restriction is easier to maintain and more effective for improving cardiometabolic health markers than greater restriction. Design A total of 77 healthy participants were randomised to a very low-carbohydrate ketogenic diet (VLCKD), low-carbohydrate diet (LCD), or moderate-low carbohydrate diet (MCD), containing 5%, 15% and 25% total energy from carbohydrate, respectively, for 12-weeks. Anthropometric and metabolic health measures were taken at baseline and at 12 weeks. Using ANOVA, both within and between-group outcomes were analysed. Results Of 77 participants, 39 (51%) completed the study. In these completers overall, significant reductions in weight and body mass index occurred ((mean change) 3.7 kg/m2; 95% confidence limits (CL): 3.8, 1.8), along with increases in high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, (0.49 mmol/L; 95% CL; 0.06, 0.92; p = 0.03), and total cholesterol concentrations (0.11 mmol/L; 95% CL; 0.00, 0.23; p = 0.05). Triglyceride (TG) levels were reduced by 0.12 mmol/L (95% CL; −0.20, 0.02; p = 0.02). No significant changes occurred between groups. The largest improvements in high density lipoprotein cholesterol (HDL-c) and TG and anthropometric changes occurred for the VLCKD group. Conclusions Low-carbohydrate, high-fat diets have a positive effect on markers of health. Adherence to the allocation of carbohydrate was more easily achieved in MCD, and LCD groups compared to VLCKD and there were comparable improvements in weight loss and waist circumference and greater improvements in HDL-c and TG with greater carbohydrate restriction.
bibliographic citation: Harvey et al. (2019) Low-carbohydrate diets differing in carbohydrate restriction improve cardiometabolic and anthropometric markers in healthy adults: A randomised clinical trial. PeerJ 7:e6273 https://doi.org/10.7717/peerj.6273
date submitted: 2018-10-02
date accepted: 2018-12-11
issued: 2019-02-05
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Harvey
  given name: Cliff J. d. C.
author list: Agent
  family name: Schofield
  given name: Grant M.
author list: Agent
  family name: Zinn
  given name: Caryn
author list: Agent
  family name: Thornley
  given name: Simon J.
author list: Agent
  family name: Crofts
  given name: Catherine
author list: Agent
  family name: Merien
  given name: Fabrice L. R.
doi: 10.7717/peerj.6273
volume: 7
issn: 2167-8359
publication name: PeerJ
publication date: 2019-02-05
copyright: © 2019 Harvey et al.
attribution name: Harvey et al.

Genome-wide identification and comparative evolutionary analysis of the Dof transcription factor family in physic nut and castor bean
type: item
type: AcademicArticle
description: DNA-binding with one finger (Dof) proteins comprise a plant-specific transcription factor family involved in plant growth, development and stress responses. This study presents a genome-wide comparison of Dof family genes in physic nut (Jatropha curcas) and castor bean (Ricinus communis), two Euphorbiaceae plants that have not experienced any recent whole-genome duplication. A total of 25 or 24 Dof genes were identified from physic nut and castor genomes, respectively, where JcDof genes are distributed across nine out of 11 chromosomes. Phylogenetic analysis assigned these genes into nine groups representing four subfamilies, and 24 orthologous groups were also proposed based on comparison of physic nut, castor, Arabidopsis and rice Dofs. Conserved microsynteny was observed between physic nut and castor Dof-coding scaffolds, which allowed anchoring of 23 RcDof genes to nine physic nut chromosomes. In contrast to how no recent duplicate was present in castor, two tandem duplications and one gene loss were found in the Dof gene family of physic nut. Global transcriptome profiling revealed diverse patterns of Jc/RcDof genes over various tissues, and key Dof genes involved in flower development and stress response were also identified in physic nut. These findings provide valuable information for further studies of Dof genes in physic nut and castor.
format: application/pdf
format: text/html
creator: Zhi Zou
creator: Xicai Zhang
subject: Genomics
subject: Plant Science
description: doi:10.7717/peerj.6354
publisher: PeerJ Inc.
rights: © 2019 Zou and Zhang
abstract: DNA-binding with one finger (Dof) proteins comprise a plant-specific transcription factor family involved in plant growth, development and stress responses. This study presents a genome-wide comparison of Dof family genes in physic nut (Jatropha curcas) and castor bean (Ricinus communis), two Euphorbiaceae plants that have not experienced any recent whole-genome duplication. A total of 25 or 24 Dof genes were identified from physic nut and castor genomes, respectively, where JcDof genes are distributed across nine out of 11 chromosomes. Phylogenetic analysis assigned these genes into nine groups representing four subfamilies, and 24 orthologous groups were also proposed based on comparison of physic nut, castor, Arabidopsis and rice Dofs. Conserved microsynteny was observed between physic nut and castor Dof-coding scaffolds, which allowed anchoring of 23 RcDof genes to nine physic nut chromosomes. In contrast to how no recent duplicate was present in castor, two tandem duplications and one gene loss were found in the Dof gene family of physic nut. Global transcriptome profiling revealed diverse patterns of Jc/RcDof genes over various tissues, and key Dof genes involved in flower development and stress response were also identified in physic nut. These findings provide valuable information for further studies of Dof genes in physic nut and castor.
bibliographic citation: Zou et al. (2019) Genome-wide identification and comparative evolutionary analysis of the Dof transcription factor family in physic nut and castor bean. PeerJ 7:e6354 https://doi.org/10.7717/peerj.6354
date submitted: 2018-10-15
date accepted: 2018-12-27
issued: 2019-02-05
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Zou
  given name: Zhi
author list: Agent
  family name: Zhang
  given name: Xicai
doi: 10.7717/peerj.6354
volume: 7
issn: 2167-8359
publication name: PeerJ
publication date: 2019-02-05
copyright: © 2019 Zou and Zhang
attribution name: Zou and Zhang

Blood parasites infecting the Hoatzin (Opisthocomus hoazin), a unique neotropical folivorous bird
type: item
type: AcademicArticle
description: The Hoatzin (Opisthocomus hoazin) is the only extant member of the order Opisthocomiformes. This unique South American bird lives in the riparian lowland vegetation characteristic of the Amazon and Orinoco basins. Hoatzins nest in communal social units close to water bodies; they are strictly folivores being the only bird with pregastric fermentation in the crop. Because of the complex logistics involved in capturing this bird, there is a knowledge gap on its parasites. This study documents two distant lineages of haemosporidian parasites (Plasmodium spp.) in a juvenile and two adults sampled in the Cojedes state, Venezuela. Although negative by microscopy, the parasite identification was possible by using molecular methods. We estimated the phylogenetic relationships on the parasite cytochrome b (cytb, 480 bp) gene and the mitochondrial DNA. We found one of the parasites lineages in two individuals (nestling and adult), and the corresponding fragment of cytb was identical to a one found in Wood Stork (Mycteria americana) from Brazil. The other lineage, found in an adult, has an identity of 469 out of 478 bp (98%) with Plasmodium sp. GAL-2012 (isolate THAMB08) from Brazil. Although a morphological description of these parasites was not possible, this is the first molecular study focusing on Hoatzin haemosporidian parasites and the first documentation of Plasmodium infections in the Hoatzin from Venezuela. Furthermore, we reported microfilaria in two adults as well as hematological parameters for six individuals. Information on hematological parameters could contribute to establishing the necessary baseline to detect underlying conditions, such as infections, in this bird species.
format: application/pdf
format: text/html
creator: M. Andreína Pacheco
creator: M. Alexandra García-Amado
creator: Jaime Manzano
creator: Nubia E. Matta
creator: Ananias A. Escalante
subject: Biodiversity
subject: Conservation Biology
subject: Genetics
subject: Parasitology
subject: Zoology
description: doi:10.7717/peerj.6361
publisher: PeerJ Inc.
rights: © 2019 Pacheco et al.
abstract: The Hoatzin (Opisthocomus hoazin) is the only extant member of the order Opisthocomiformes. This unique South American bird lives in the riparian lowland vegetation characteristic of the Amazon and Orinoco basins. Hoatzins nest in communal social units close to water bodies; they are strictly folivores being the only bird with pregastric fermentation in the crop. Because of the complex logistics involved in capturing this bird, there is a knowledge gap on its parasites. This study documents two distant lineages of haemosporidian parasites (Plasmodium spp.) in a juvenile and two adults sampled in the Cojedes state, Venezuela. Although negative by microscopy, the parasite identification was possible by using molecular methods. We estimated the phylogenetic relationships on the parasite cytochrome b (cytb, 480 bp) gene and the mitochondrial DNA. We found one of the parasites lineages in two individuals (nestling and adult), and the corresponding fragment of cytb was identical to a one found in Wood Stork (Mycteria americana) from Brazil. The other lineage, found in an adult, has an identity of 469 out of 478 bp (98%) with Plasmodium sp. GAL-2012 (isolate THAMB08) from Brazil. Although a morphological description of these parasites was not possible, this is the first molecular study focusing on Hoatzin haemosporidian parasites and the first documentation of Plasmodium infections in the Hoatzin from Venezuela. Furthermore, we reported microfilaria in two adults as well as hematological parameters for six individuals. Information on hematological parameters could contribute to establishing the necessary baseline to detect underlying conditions, such as infections, in this bird species.
bibliographic citation: Pacheco et al. (2019) Blood parasites infecting the Hoatzin (Opisthocomus hoazin), a unique neotropical folivorous bird. PeerJ 7:e6361 https://doi.org/10.7717/peerj.6361
date submitted: 2018-09-07
date accepted: 2018-12-30
issued: 2019-02-05
is part of: PeerJ
license: http://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Pacheco
  given name: M. Andreína
author list: Agent
  family name: García-Amado
  given name: M. Alexandra
author list: Agent
  family name: Manzano
  given name: Jaime
author list: Agent
  family name: Matta
  given name: Nubia E.
author list: Agent
  family name: Escalante
  given name: Ananias A.
doi: 10.7717/peerj.6361
volume: 7
issn: 2167-8359
publication name: PeerJ
publication date: 2019-02-05
copyright: ©2019 Pacheco et al.
attribution name: Pacheco et al.

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