CeRNA network analysis and functional enrichment of salt sensitivity of blood pressure by weighted-gene co-expression analysis
Background Salt sensitivity of blood pressure (SSBP) is an independent risk factor for cardiovascular disease. The pathogenic mechanisms of SSBP are still uncertain. This study aimed to construct the co-regulatory network of SSBP and data mining strategy based on the competitive endogenous RNA (ceRNA) theory. Methods LncRNA and mRNA microarray was performed to screen for candidate RNAs. Four criteria were used to select the potential differently expressed RNAs. The weighted correlation network analysis (WGCNA) package of R software and target miRNA and mRNA prediction online databases were used to construct the ceRNA co-regulatory network and discover the pathways related to SSBP. Gene ontology enrichment, gene set enrichment analysis (GSEA) and KEGG pathway analysis were performed to explore the functions of hub genes in networks. Results There were 274 lncRNAs and 36 mRNAs that differently expressed between salt-sensitive and salt-resistant groups (P < 0.05). Using WGCNA analysis, two modules were identified (blue and turquoise). The blue module had a positive relationship with salt-sensitivity (R = 0.7, P < 0.01), high-density lipoprotein (HDL) (R = 0.53, P = 0.02), and total cholesterol (TC) (R = 0.55, P = 0.01). The turquoise module was positively related with triglyceride (TG) (R = 0.8, P < 0.01) and low-density lipoprotein (LDL) (R = 0.54, P = 0.01). Furthermore, 84 ceRNA loops were identified and one loop may be of great importance for involving in pathogenesis of SSBP. KEGG analysis showed that differently expressed mRNAs were mostly enriched in the SSBP-related pathways. However, the enrichment results of GSEA were mainly focused on basic physical metabolic processes. Conclusion The microarray data mining process based on WGCNA co-expression analysis had identified 84 ceRNA loops that closely related with known SSBP pathogenesis. The results of our study provide implications for further understanding of the pathogenesis of SSBP and facilitate the precise diagnosis and therapeutics.
Cao et al. (2019) CeRNA network analysis and functional enrichment of salt sensitivity of blood pressure by weighted-gene co-expression analysis. PeerJ 7:e7534 https://doi.org/10.7717/peerj.7534
Genome skimming is a low-cost and robust strategy to assemble complete mitochondrial genomes from ethanol preserved specimens in biodiversity studies
Global loss of biodiversity is an ongoing process that concerns both local and global authorities. Studies of biodiversity mainly involve traditional methods using morphological characters and molecular protocols. However, conventional methods are a time consuming and resource demanding task. The development of high-throughput sequencing (HTS) techniques has reshaped the way we explore biodiversity and opened a path to new questions and novel empirical approaches. With the emergence of HTS, sequencing the complete mitochondrial genome became more accessible, and the number of genome sequences published has increased exponentially during the last decades. Despite the current state of knowledge about the potential of mitogenomics in phylogenetics, this is still a relatively under-explored area for a multitude of taxonomic groups, especially for those without commercial relevance, non-models organisms and with preserved DNA. Here we take the first step to assemble and annotate the genomes from HTS data using a new protocol of genome skimming which will offer an opportunity to extend the field of mitogenomics to under-studied organisms. We extracted genomic DNA from specimens preserved in ethanol. We used Nextera XT DNA to prepare indexed paired-end libraries since it is a powerful tool for working with diverse samples, requiring a low amount of input DNA. We sequenced the samples in two different Illumina platform (MiSeq or NextSeq 550). We trimmed raw reads, filtered and had their quality tested accordingly. We performed the assembly using a baiting and iterative mapping strategy, and the annotated the putative mitochondrion through a semi-automatic procedure. We applied the contiguity index to access the completeness of each new mitogenome. Our results reveal the efficiency of the proposed method to recover the whole mitogenomes of preserved DNA from non-model organisms even if there are gene rearrangement in the specimens. Our findings suggest the potential of combining the adequate platform and library to the genome skimming as an innovative approach, which opens a new range of possibilities of its use to obtain molecular data from organisms with different levels of preservation.
Trevisan et al. (2019) Genome skimming is a low-cost and robust strategy to assemble complete mitochondrial genomes from ethanol preserved specimens in biodiversity studies. PeerJ 7:e7543 https://doi.org/10.7717/peerj.7543
Biochar application significantly affects the N pool and microbial community structure in purple and paddy soils
Background The increasing demand for food production has resulted in the use of large quantities of chemical fertilizers. This has created major environmental problems, such as increased ammonia volatilization, N2O emission, and nitrogen (N) leaching from agricultural soil. In particular, the utilization rate of N fertilizer is low in subtropical southern parts of China due to high rainfall. This causes not only large financial losses in agriculture, but also serious environmental pollution. Methods In this study, 16S rDNA-based analysis and static-chamber gas chromatography were used to elucidate the effects of continuous straw biochar application on the N pool and bacteria environment in two typical soil types, purple and paddy soils, in southern China. Results Straw biochar application (1) improved the soil N pool in both rhizosphere and non-rhizosphere soils; (2) significantly reduced the emission of N2O, with no difference in emission between 1 and 2 years of application; (3) increased the abundance of N-processing bacteria in the soil and altered the bacterial community structure; and (4) improved the tobacco yield and N use efficiency in paddy soil. These findings suggest that, in southern China, the application of straw biochar can promote N transformation in purple and paddy soils and reduce the emission of the greenhouse gas N2O.
Yan et al. (2019) Biochar application significantly affects the N pool and microbial community structure in purple and paddy soils. PeerJ 7:e7576 https://doi.org/10.7717/peerj.7576
Notes on vocalizations of Brazilian amphibians IV: advertisement calls of 20 Atlantic Forest frog species
Bioacoustics is a powerful tool used for anuran species diagnoses, given that advertisement calls are signals related to specific recognition and mate attraction. Thus, call descriptions can support species taxonomy. In spite of that, call descriptions are lacking for many species, delaying advances in biodiversity research. Here, we describe the advertisement calls of 20 anuran species from the Brazilian Atlantic Forest. We accessed 50 digital recordings deposited in the Fonoteca Neotropical Jacques Vielliard. Acoustic analyses were carried out in the software Raven pro 1.5. We provide a general comparison of call structure among species inside taxonomic groups and genera. The vocalizations described here belong to poorly known species, which are representatives of six families: Brachycephalidae, Bufonidae, Ceratophryidae, Cycloramphidae, Hylidae, and Phyllomedusidae. Despite this, still there are 163 species of anurans from Atlantic Forest with calls not formally described. Our work represents an important step in providing data for a taxonomic perspective and improving the knowledge of the Atlantic Forest anuran diversity.
Forti et al. (2019) Notes on vocalizations of Brazilian amphibians IV: advertisement calls of 20 Atlantic Forest frog species. PeerJ 7:e7612 https://doi.org/10.7717/peerj.7612
Analysis of small RNA changes in different Brassica napus synthetic allopolyploids
Allopolyploidy is an evolutionary and mechanisticaly intriguing process involving the reconciliation of two or more sets of diverged genomes and regulatory interactions, resulting in new phenotypes. In this study, we explored the small RNA changes of eight F2 synthetic B. napus using small RNA sequencing. We found that a part of miRNAs and siRNAs were non-additively expressed in the synthesized B. napus allotetraploid. Differentially expressed miRNAs and siRNAs differed among eight F2 individuals, and the differential expression of miR159 and miR172 was consistent with that of flowering time trait. The GO enrichment analysis of differential expression miRNA target genes found that most of them were concentrated in ATP-related pathways, which might be a potential regulatory process contributing to heterosis. In addition, the number of siRNAs present in the offspring was significantly higher than that of the parent, and the number of high parents was significantly higher than the number of low parents. The results have shown that the differential expression of miRNA lays the foundation for explaining the trait separation phenomenon, and the significant increase of siRNA alleviates the shock of the newly synthesized allopolyploidy. It provides a new perspective between small RNA changes and trait separation in the early stages of allopolyploid polyploid formation.
Wei et al. (2019) Analysis of small RNA changes in different Brassica napus synthetic allopolyploids. PeerJ 7:e7621 https://doi.org/10.7717/peerj.7621
EnContact: predicting enhancer-enhancer contacts using sequence-based deep learning model
Chromatin contacts between regulatory elements are of crucial importance for the interpretation of transcriptional regulation and the understanding of disease mechanisms. However, existing computational methods mainly focus on the prediction of interactions between enhancers and promoters, leaving enhancer-enhancer (E-E) interactions not well explored. In this work, we develop a novel deep learning approach, named Enhancer-enhancer contacts prediction (EnContact), to predict E-E contacts using genomic sequences as input. We statistically demonstrated the predicting ability of EnContact using training sets and testing sets derived from HiChIP data of seven cell lines. We also show that our model significantly outperforms other baseline methods. Besides, our model identifies finer-mapping E-E interactions from region-based chromatin contacts, where each region contains several enhancers. In addition, we identify a class of hub enhancers using the predicted E-E interactions and find that hub enhancers tend to be active across cell lines. We summarize that our EnContact model is capable of predicting E-E interactions using features automatically learned from genomic sequences.
Gan et al. (2019) EnContact: predicting enhancer-enhancer contacts using sequence-based deep learning model. PeerJ 7:e7657 https://doi.org/10.7717/peerj.7657
Screening and identification of SipC-interacting proteins in Salmonella enteritidis using Gal4 yeast two-hybrid system in duck
The zoonotic pathogen Salmonella not only reduces the production performance in ducks, but also poses a serious threat to human health through eggs and pollutes water bodies through feces. SipC, an effector protein of type III secretion systems (T3SS) in Salmonella, mediates translocation of effectors into the eukaryotic host. However, the precise role of SipC effectors remains unknown in ducks. In this study, the SipC from duck granulosa cells (dGCs) was selected as bait, and the SipC-interacting proteins in Salmonella enteritidis (SE) were screened using Gal4 yeast two-hybrid system in duck. Twelve SipC-interacting proteins were identified. Among those, the p53-effector related to PMP-22 (PERP) and TGF-β activated kinase 1-binding protein 2 (TAB2) were selected to further confirm the function by GST pull-down in vitro. Over-expression of PERP resulted in not only increasing SE adhesion and invasion but also triggering the production of IL-1β and IFN-α in SE infected dGCs, while knock-down PERP showed the opposite tendency (P < 0.01). In addition, TAB2 significantly induced the production of IL-6, IL-1β, IFN-α, and INF-γ in SE infected dGCs (P < 0.05), but did not cause obvious changes in SE adhesion and invasion. When the sipC in SE was deleted, the activities of duck PERP and TAB2 were abolished because they could not bind to SipC. Taken together, although the protein of PERP and TAB2 can interact with SipC, their mechanisms were different in duck challenged by SE. Therefore, PERP was involved in SE invasion and inflammatory response of dGC ovaries, and TAB2 only contributed to dGCs inflammatory response, which provided critical insights about the mechanism in host- bacterium protein interactions during Salmonella invasion in duck.
Zhang et al. (2019) Screening and identification of SipC-interacting proteins in Salmonella enteritidis using Gal4 yeast two-hybrid system in duck. PeerJ 7:e7663 https://doi.org/10.7717/peerj.7663
Searching for phylogenetic patterns of Symbiodiniaceae community structure among Indo-Pacific Merulinidae corals
Over half of all extant stony corals (Cnidaria: Anthozoa: Scleractinia) harbour endosymbiotic dinoflagellates of the family Symbiodiniaceae, forming the foundational species of modern shallow reefs. However, whether these associations are conserved on the coral phylogeny remains unknown. Here we aim to characterise Symbiodiniaceae communities in eight closely-related species in the genera Merulina, Goniastrea and Scapophyllia, and determine if the variation in endosymbiont community structure can be explained by the phylogenetic relatedness among hosts. We perform DNA metabarcoding of the nuclear internal transcribed spacer 2 using Symbiodiniaceae-specific primers on 30 coral colonies to recover three major endosymbiont clades represented by 23 distinct types. In agreement with previous studies on Southeast Asian corals, we find an abundance of Cladocopium and Durusdinium, but also detect Symbiodinium types in three of the eight coral host species. Interestingly, differences in endosymbiont community structure are dominated by host variation at the intraspecific level, rather than interspecific, intergeneric or among-clade levels, indicating a lack of phylogenetic constraint in the coral-endosymbiont association among host species. Furthermore, the limited geographic sampling of four localities spanning the Western and Central Indo-Pacific preliminarily hints at large-scale spatial structuring of Symbiodiniaceae communities. More extensive collections of corals from various regions and environments will help us better understand the specificity of the coral-endosymbiont relationship.
Leveque et al. (2019) Searching for phylogenetic patterns of Symbiodiniaceae community structure among Indo-Pacific Merulinidae corals. PeerJ 7:e7669 https://doi.org/10.7717/peerj.7669
Red-crowned crane (Grus japonensis) prefers postharvest reed beds during winter period in Yancheng National Nature Reserve
Reed beds represent an important habitat for the survival of birds by providing favorable foraging and reproduction conditions. Reed management, as a traditional agricultural activity, primarily includes water level control and vegetation removal by cutting. Red-crowned crane (Grus japonensis) is one of the most endangered cranes, and their population continues to decline due to habitat loss caused by artificial activities. A lack of research relating to how reed management affects crane habitat distribution patterns throughout the wintering period hinders our ability to offer conservation recommendations. In the present study, we explored the effect of reed management on the habitat distribution patterns and analyzed the food resources of red-crowned crane in the Yancheng National Nature Reserve (YNNR). According to the reed management activities in December, we divided the wintering period into two phases: the preharvest period and the postharvest period. Throughout the wintering period, the number of cranes recorded in the common seepweed (Suaeda glauca) tidal flats remained stable, but cranes were rarely recorded in the smooth cordgrass (Spartina alterniflora) tidal flats and aquaculture fish ponds. The number of cranes, however, showed a noticeable fluctuation in the reed beds during the two periods. Before the reed harvest, only a small proportion of cranes were recorded in the reed beds (relative abundance = 2.9%). However, more cranes (relative abundance = 61.0%) were recorded after the reed harvest. Water was introduced from adjacent rivers and fish ponds to submerge the cut reed beds. Changes in potential animal food resources (items and biomass) might be one of the vital reasons for the preference of cranes to the postharvest reed beds. Our results suggest that traditional reed management in the YNNR could benefit this flagship crane species that winters in the wetland system. However, as reed harvest has been forbidden in the core zone for conservation purposes since 2016, further research is needed to verify whether forbidding the harvest of reeds is reasonable.
Xu et al. (2019) Red-crowned crane (Grus japonensis) prefers postharvest reed beds during winter period in Yancheng National Nature Reserve. PeerJ 7:e7682 https://doi.org/10.7717/peerj.7682
Niches and climate-change refugia in hundreds of species from one of the most arid places on Earth
Background and Aims Global climate change is a major threat to biodiversity worldwide. Several arid areas might expand in the future, but it is not clear if this change would be positive or negative for arid-adapted lineages. Here, we explore whether climatic niche properties are involved in the configuration of climate refugia and thus in future species trends. Methods To estimate putative climate refugia and potential expansion areas, we used maximum entropy models and four climate-change models to generate current and future potential distributions of 142 plant species endemic to the Atacama and mediterranean Chilean ecosystems. We assessed the relationship between the similarity and breadth of thermal and precipitation niches with the size of climate refugia and areas of potential expansions. Key Results We found a positive relationship between breadth and similarity for thermal niche with the size of climate refugia, but only niche similarity of the thermal niche was positively related with the size of expansion areas. Although all lineages would reduce their distributions in the future, few species are predicted to be at risk of extinction in their current distribution, and all of them presented potential expansion areas. Conclusion Species with a broad niche and niche dissimilarity will have larger refugia, and species with niche dissimilarity will have larger expansion areas. In addition, our prediction for arid lineages shows that these species will be moderately affected by climate change.
Duarte et al. (2019) Niches and climate-change refugia in hundreds of species from one of the most arid places on Earth. PeerJ 7:e7409 https://doi.org/10.7717/peerj.7409