title: PeerJ description: Articles published in PeerJ link: https://peerj.com/articles/index.rss3?journal=peerj&page=704 creator: info@peerj.com PeerJ errorsTo: info@peerj.com PeerJ language: en title: Tracing RNA viruses associated with Nudibranchia gastropods link: https://peerj.com/articles/13410 last-modified: 2022-05-13 description: BackgroundNudibranchia is an under-studied taxonomic group of gastropods, including more than 3,000 species with colourful and extravagant body shapes and peculiar predatory and defensive strategies. Although symbiosis with bacteria has been reported, no data are available for the nudibranch microbiome nor regarding viruses possibly associated with these geographically widespread species.MethodsBased on 47 available RNA sequencing datasets including more than two billion reads of 35 nudibranch species, a meta-transcriptome assembly was constructed. Taxonomic searches with DIAMOND, RNA-dependent-RNA-polymerase identification with palmscan and viral hallmark genes identification by VirSorter2 in combination with CheckV were applied to identify genuine viral genomes, which were then annotated using CAT.ResultsA total of 20 viral genomes were identified as bona fide viruses, among 552 putative viral contigs resembling both RNA viruses of the Negarnaviricota, Pisuviricota, Kitrinoviricota phyla and actively transcribing DNA viruses of the Cossaviricota and Nucleocytoviricota phyla. The 20 commonly identified viruses showed similarity with RNA viruses identified in other RNA-seq experiments and can be putatively associated with bacteria, plant and arthropod hosts by co-occurence analysis. The RNA samples having the highest viral abundances showed a heterogenous and mostly sample-specific distribution of the identified viruses, suggesting that nudibranchs possess diversified and mostly unknown viral communities. creator: Umberto Rosani uri: https://doi.org/10.7717/peerj.13410 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Rosani title: Exploring the spatiotemporal changes in carbon storage under different development scenarios in Jiangsu Province, China link: https://peerj.com/articles/13411 last-modified: 2022-05-13 description: Carbon storage (CS) is closely linked to the global challenge of climate change. Land use/cover (LULC) change is the main factor driving changes in CS, and evaluating the impact of LULC changes on CS is important for carbon balance. Taking Jiangsu Province as an example, we used the Integrated Valuation of Ecosystem Services and Trade-offs model to analyze the spatiotemporal changes in CS during 2000–2015. Then we coupled it with the patch-generating land use simulation model to simulate and predict LULC and CS in 2050 under four different development plans. The results showed that LULC change in Jiangsu Province was manifested mainly as transformation of cropland to construction land (3,485 km2) and cropland to water body (470 km2). The high value area for CS was concentrated mainly in forest land, water body and grassland, whereas the low value area was concentrated mainly in construction land. During 2000–2015, CS decreased by 0.23 Tg, and during 2015–2050, CS was predicted to decrease by 0.16, 1.69, 0.02, and 0.10 Tg under the baseline, fast, slow and harmonious development scenarios. The conversion of a large amount of cropland to construction land was the main cause of CS loss. In all scenarios, the carbon loss was the largest in southern Jiangsu and lowest in central Jiangsu. It is necessary to balance the conflict between economic development and ecological protection during the process of urbanization. This study can provide an important reference for decision makers during the formulation of regional development models and ecological management strategies. creator: Xiaomian Zhang creator: Jun Wang creator: Chunlei Yue creator: Shuai Ma creator: Liang-Jie Wang uri: https://doi.org/10.7717/peerj.13411 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Zhang et al. title: Identification of key differential genes in intimal hyperplasia induced by left carotid artery ligation link: https://peerj.com/articles/13436 last-modified: 2022-05-13 description: BackgroundIntimal hyperplasia is a common pathological process of restenosis following angioplasty, atherosclerosis, pulmonary hypertension, vein graft stenosis, and other proliferative diseases. This study aims to screen for potential novel gene targets and mechanisms related to vascular intimal hyperplasia through an integrated microarray analysis of the Gene Expression Omnibus Database (GEO) database.Material and MethodsThe gene expression profile of the GSE56143 dataset was downloaded from the Gene Expression Omnibus database. Functional enrichment analysis, protein-protein interaction (PPI) network analysis, and the transcription factor (TF)-target gene regulatory network were used to reveal the biological functions of differential genes (DEGs). Furthermore, the expression levels of the top 10 key DEGs were verified at the mRNA and protein level in the carotid artery 7 days after ligation.ResultsA total of 373 DEGs (199 upregulated DEGs and 174 downregulated DEGs) were screened. These DEGs were significantly enriched in biological processes, including immune system process, cell adhesion, and several pathways, which were mainly associated with cell adhesion molecules and the regulation of the actin cytoskeleton. The top 10 key DEGs (Ptprc, Fn1, Tyrobp, Emr1, Itgb2, Itgax, CD44, Ctss, Ly86, and Aif1) acted as key genes in the PPI network. The verification of these key DEGs at the mRNA and protein levels was consistent with the results of the above-mentioned bioinformatics analysis.ConclusionThe present study identified key genes and pathways involved in intimal hyperplasia induced by carotid artery ligation. These results improved our understanding of the mechanisms underlying the development of intimal hyperplasia and provided candidate targets. creator: Lina Zhang creator: Jianjun Gu creator: Sichuan Wang creator: Fuming He creator: Kaizheng Gong uri: https://doi.org/10.7717/peerj.13436 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Zhang et al. title: The Microphenotron: a novel method for screening plant growth-promoting rhizobacteria link: https://peerj.com/articles/13438 last-modified: 2022-05-13 description: BackgroundThe ‘Microphenotron’ is an automated screening platform that uses 96-well microtiter plates to test the response of seedlings to natural products. This system allows monitoring the phenotypic effect of a large number of small molecules. Here, this model system was used to study the effect of phytohormones produced by plant growth-promoting rhizobacteria (PGPR) on the growth of wild-type and mutant lines of Arabidopsis thaliana.MethodsIn the present study, high-throughput screening based on ‘Microphenotron’ was used to screen PGPRs. Rhizobacteria were isolated from the rhizosphere of Acacia Arabica, which was growing in saline habitats. The phylogeny of these rhizobacteria was determined by 16S rRNA gene sequencing. Strains were screened for plant growth-promoting traits such as auxin production, 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, and phosphate solubilization. Ultra-Performance Liquid Chromatography (UPLC) was used to detect the presence of different indolic compounds. Finally, PGPR were evaluated to enhance the growth of A. thaliana in the ‘Microphenotron’ system and pot trials.ResultsSelected rhizobacteria strains showed positive results for multiple plant-growth promoting traits. For instance, strain (S-6) of Bacillus endophyticus exhibited the highest ACC-deaminase activity. UPLC analysis indicated the presence of different indolic compounds in bacterial extracts that included indole lactic acid (ILA), indole carboxylic acid (ICA), and indole-3-acetic acid (IAA). Two strains (S-7 and S-11) of Psychrobacter alimentarius produced the most IAA, ICA and ILA. A screening bioassay through 96-well microtiter plates with wild-type Col. N6000 showed an increase in root growth and proliferation. The highest twofold increase was recorded in root growth with B. thuringiensis S-26 and B. thuringiensis S-50. In pot trials, mutant lines of A. thaliana impaired for auxin signaling showed that B. endophyticus S-6, Psy. alimenterius S-11, Enterobacter asburiae S-24 and B. thuringiensis S-26 used auxin signaling for plant growth promotion. Similarly, for ethylene insensitive mutant lines (ein2.5 and etr1), Prolinoborus fasciculus S-3, B. endophyticus S-6, Psy. alimenterius S-7, E. asburiae S-24, and B. thuringiensis S-26 showed the involvement of ethylene signaling. However, the growth promotion pattern for most of the strains indicated the involvement of other mechanisms in enhancing plant growth. The result of Microphenotron assays generally agreed with pot trials with mutant and wild type A. thaliana varieties. Bacterial strains that induced the highest growth response by these cultivars in the ‘Microphenotron’ promoted plant growth in pot trials. This suggests that Microphenotron can accelerate the evaluation of PGPR for agricultural applications. creator: Asif Raheem creator: Basharat Ali uri: https://doi.org/10.7717/peerj.13438 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Raheem and Ali title: Lipopolysaccharide-activated macrophages regulate the osteogenic differentiation of bone marrow mesenchymal stem cells through exosomes link: https://peerj.com/articles/13442 last-modified: 2022-05-13 description: BackgroundPeriodontal tissue regeneration is the ultimate goal of periodontitis treatment. Exosomes are nanoscale vesicles secreted by cells that participate in and regulate the physiological activities between cells. However, the relationship between inflammatory macrophage-derived exosomes and osteoblast differentiation in periodontitis has not been thoroughly reported. Here, we attempt to explore the role of inflammatory macrophage-derived exosomes in crosstalk with osteoblasts.MethodsPorphyromonas gingivalis lipopolysaccharide was used to stimulate macrophages and inflate their inflammatory cellular state. Exosomes were extracted from inflammatory macrophages using supercentrifugation, and their characteristics were detected by transmission electron microscopy, particle size analysis, and Western blotting. Exosome uptake bybone marrow mesenchymal stem cells (BMSCs) was observed by fluorescence microscopy. The effects of exosomes on the BMSC inflammatory response and on osteogenic differentiation were detected by quantitative polymerase chain reaction and Western blot analysis. Alkaline phosphatase activity was tested for verification.ResultsWe successfully extracted and identified inflammatory macrophage-derived exosomes and observed that BMSCs successfully took up exosomes. Inflammatory macrophage-derived exosomes upregulated the expression levels of the inflammatory factors interleukin-6 and tumour necrosis factor-alpha in BMSCs and mediated inflammatory stimulation. Additionally, they inhibited the transcription levels of the osteogenic genes alkaline phosphatase, type I collagen, and Runt-related transcription factor 2 as well as the alkaline phosphatase activity, while the use of the exosome inhibitor GW4869 attenuated this effect.ConclusionOur study shows that macrophages in periodontitis can mediate inflammatory stimulation and inhibit the osteogenic differentiation of bone marrow mesenchymal stem cells through the exosome pathway. Interference with exosome secretion is likely to be a promising method for bone tissue regeneration in inflammatory states. creator: Xiao Song creator: Yiwen Xue creator: Siyu Fan creator: Jing Hao creator: Runzhi Deng uri: https://doi.org/10.7717/peerj.13442 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Song et al. title: A field test of forest canopy structure measurements with the CanopyCapture smartphone application link: https://peerj.com/articles/13450 last-modified: 2022-05-13 description: BackgroundSeveral smartphone applications have been developed for the purpose of low-cost and convenient assessments of vegetation canopy structure and understorey illumination. Like standard hemispherical photography, most of these applications require user decisions about image processing, posing challenges for repeatability of measurements. Here I report a test of CanopyCapture, an application that instantaneously estimates percentage canopy gap fraction without any input from the user, and has the added advantage of an intuitive levelling mechanism.MethodsGap fraction estimates by CanopyCapture were compared with gap fraction values computed by the LAI-2200C Canopy Analyzer, in two contrasting evergreen temperate forests in New Zealand: an even-aged southern beech (Nothofagus) stand and an old-growth podocarp/broadleaf forest. These comparisons were repeated using a wide-angle adapter to enhance the smartphone camera’s field of view from 45 to 65°. I also asked if CanopyCapture results depended on sky condition (sunny vs. overcast) and on the type of smartphone used.ResultsCanopyCapture output was significantly correlated with gap fraction computed by the LAI-2200C (R2 = 0.39), and use of the wide-angle adapter lifted this value to 0.56. However, CanopyCapture output was not significantly correlated with LAI-2200C output in the even-aged Nothofagus stand, where there was less spatial variation in canopy structure. Despite being much less sensitive to variation in gap fraction than the LAI-2200C, CanopyCapture was nevertheless able to detect differences in average gap fraction between the two forests studied. CanopyCapture results beneath intact canopies were not significantly affected by sky condition, but reflection of direct light off tree trunks in sunny weather caused slight overestimation of gap fraction beneath broken canopies and gaps. Uneven or patchy cloud cover can also cause erroneous readings beneath large canopy openings. Three different models of smartphone gave different results.ConclusionsCanopyCapture offers a rapid and repeatable proxy for comparisons of average canopy gap fraction in multiple stands/forests, provided large sample sizes are used. Measurement under even overcast skies is recommended, and studies involving multiple operators will need to standardize smartphones to ensure comparability of results. Although wide-angle adapters can improve performance, CanopyCapture’s low sensitivity prevents high-resolution comparisons of the light environments of individual understorey plants within a stand. creator: Christopher H. Lusk uri: https://doi.org/10.7717/peerj.13450 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Lusk title: Soil properties and microbial communities of spring maize filed in response to tillage with straw incorporation and nitrogen fertilization in northeast China link: https://peerj.com/articles/13462 last-modified: 2022-05-13 description: Soil enzymes and microorganisms are both important to maintaining good soil quality and are also sensitive to changes in agricultural management. The individual effects of tillage, straw incorporation and nitrogen (N) fertilization on soil enzymes and microflora have been widely acknowledged, but their interactive effect remains largely unknown. In a 5–year in–situ field study, effects of rotary (RTS) and plow tillage (PTS) practices with straw incorporation combined with three N fertilization levels (0 kg N ha–1, CK; 187 kg N ha–1, MN; 337 kg N ha–1, HN) on soil enzyme activities and microbial communities were assessed. Our results showed that the activities of β–glucosidase (βG), N–acetylglucosaminidase (NAG) and acid phosphatase (APH) were improved in RTS+MN. The bacterial and fungal abundances in RTS+MN and RTS+HN were 1.27–27.51 times higher than those in other treatment groups. However, the bacterial and fungal alpha diversities were enhanced in PTS+MN and PTS+CK compared with other treatments, respectively. Proteobacteria and Basidiomycota were the predominant phylum for the respective bacterial and fungal communities. Moreover, significant interactive effects were found in the fungal community composition, but only minor impacts were observed on the bacterial community composition. Soil water content and penetration resistance contributed more to the soil enzyme activity and microbial community than other soil properties investigated, whereas there was a significant positive correlation between βG and APH activities and microbial abundance. These findings can provide new insights into tillage with straw incorporation and N fertilization on maize cultivation in northeast China. creator: Pengxiang Sui creator: Ping Tian creator: Zhengyu Wang creator: Hongli Lian creator: Yadong Yang creator: Ziqi Ma creator: Ying Jiang creator: Jinyu Zheng creator: Hua Qi uri: https://doi.org/10.7717/peerj.13462 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Sui et al. title: Linking multi-level population dynamics: state, role, and population link: https://peerj.com/articles/13315 last-modified: 2022-05-12 description: The dynamics of an ecological community can be described at different focal scales of the species, such as individual states or the population level. More detailed descriptions of ecological dynamics offer more information, but produce more complex models that are difficult to analyze. Adequately controlling the model complexity and the availability of multiple descriptions of the concerned dynamics maximizes our understanding of ecological dynamics. One of the central goals of ecological studies is to develop links between multiple descriptions of an ecological community. In this article, starting from a nonlinear state-level description of an ecological community (generalized McKendrick–von Foerster model), role-level and population-level descriptions (Lotka–Volterra model) are derived in a consistent manner. The role-level description covers a wider range of situations than the population-level description. However, using the established connections, it is demonstrated that the population-level description can be used to predict the equilibrium status of the role-level description. This approach connects state-, role-, and population-level dynamics consistently, and offers a justification for the multiple choices of model description. creator: Nao Takashina uri: https://doi.org/10.7717/peerj.13315 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Takashina title: Non-destructive monitoring of 3D cell cultures: new technologies and applications link: https://peerj.com/articles/13338 last-modified: 2022-05-12 description: 3D cell cultures are becoming the new standard for cell-based in vitro research, due to their higher transferrability toward in vivo biology. The lack of established techniques for the non-destructive quantification of relevant variables, however, constitutes a major barrier to the adoption of these technologies, as it increases the resources needed for the experimentation and reduces its accuracy. In this review, we aim at addressing this limitation by providing an overview of different non-destructive approaches for the evaluation of biological features commonly quantified in a number of studies and applications. In this regard, we will cover cell viability, gene expression, population distribution, cell morphology and interactions between the cells and the environment. This analysis is expected to promote the use of the showcased technologies, together with the further development of these and other monitoring methods for 3D cell cultures. Overall, an extensive technology shift is required, in order for monolayer cultures to be superseded, but the potential benefit derived from an increased accuracy of in vitro studies, justifies the effort and the investment. creator: Marilisa Cortesi creator: Emanuele Giordano uri: https://doi.org/10.7717/peerj.13338 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Cortesi and Giordano title: The choice of reference point for computing sagittal plane angular momentum affects inferences about dynamic balance link: https://peerj.com/articles/13371 last-modified: 2022-05-12 description: BackgroundMeasures of whole-body angular momentum in the sagittal plane are commonly used to characterize dynamic balance during human walking. To compute angular momentum, one must specify a reference point about which momentum is calculated. Although biomechanists primarily compute angular momentum about the center of mass (CoM), momentum-based controllers for humanoid robots often use the center of pressure. Here, we asked if the choice of the reference point influences interpretations of how dynamic balance is controlled in the sagittal plane during perturbed walking.MethodsEleven healthy young individuals walked on a dual-belt treadmill at their self-selected speed. Balance disturbances were generated by treadmill accelerations of varying magnitudes and directions. We computed angular momentum about two reference points: (1) the CoM or (2) the leading edge of the base of support and then projected it along the mediolateral axes that pass through either of the reference points as the sagittal plane angular momentum. We also performed principal component analysis to determine if the choice of reference point influences our interpretations of how intersegmental coordination patterns contribute to perturbation recovery.ResultsWe found that the peak angular momentum was correlated with perturbation amplitude and the slope of this relationship did not differ between reference points. One advantage of using a reference point at the CoM is that one can easily determine how the momenta from contralateral limbs, such as the left and right legs, offset one another to regulate the whole-body angular momentum. Alternatively, analysis of coordination patterns referenced to the leading edge of the base of support may provide more insight into the inverted-pendulum dynamics of walking during responses to sudden losses of balance. creator: Chang Liu creator: Sungwoo Park creator: James Finley uri: https://doi.org/10.7717/peerj.13371 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Liu et al.