Analysis of chromosome karyotype and genome size in echiuran Urechis unicinctus Drasche, 1880 (Polychaeta, Urechidae)

Karyotype and genome size are two primary cytogenetic characteristics of species, which are of great significance to the study of cytogenetics, taxonomy, phylogenesis, evolution as well as molecular biology. However, this basic cytogenetic information in echiurans is lacking. Therefore, we analyzed characteristics of karyotype and genome size in the echiuran worm Urechis unicinctus Drasche, 1880. In this study, coelomic cells of U. unicinctus were used for analyzing the genome size by a flow cytometry with chicken erythrocytes as DNA standard, and the 2C DNA content was determined to be 1.85 pg, which was corresponded to the genome size of 904.58 Mbp approximately. Furthermore, trochophores of U. unicinctus were dissociated and cells were utilized for preparing the chromosomes stained with DAPI, and the karyotype was determined as 2n = 30 (10m + 6sm + 6st + 8t), FN=52. Our data provided the basic cytogenetic information of U. unicinctus, which could be utilized in taxonomic study and whole-genome sequencing in future

Genetic variants in PDSS1 and SLC16A6 of the ketone body metabolic pathway predict cutaneous melanoma-specific survival

A few single-nucleotide polymorphisms (SNPs) have been identified to be associated with cutaneous melanoma (CM) survival though genome-wide association studies, but stringent multiple testing corrections required for the hypothesis-free testing may have masked some true associations. Using a hypothesis-driven analysis approach, we sought to evaluate associations between SNPs in ketone body metabolic pathway genes and CM survival. We comprehensively assessed associations between 4,196 (538 genotyped and 3,658 imputed) common SNPs in ketone body metabolic pathway genes and CM survival, using a dataset of 858 patients of a case-control study from The University of Texas M.D. Anderson Cancer Center as the discovery set and another dataset of 409 patients from the Nurses’ Health Study and the Health Professionals Follow-up Study as the replication set. There were 95/858 (11.1%) and 48/409 (11.5%) patients who died of CM, respectively. We identified two independent SNPs (i.e., PDSS1 rs12254548 G>C and SLC16A6 rs71387392 G>A) that were associated with CM survival, with allelic hazards ratios of 0.58 (95% confidence interval [CI]=0.44-0.76, P=9.00×10−5) and 1.98 (95% CI=1.34-2.94, P=6.30×10−4), respectively. Additionally, associations between genotypes of the SNPs and mRNA expression levels of their corresponding genes support the biologic plausibility of a role for these two variants in CM tumor progression and survival. Once validated by larger studies, PDSS1 rs12254548 and SLC16A6 rs71387392 may be biomarker for CM survival

Full-length transcriptome analysis provides insights into larval shell formation in Mulinia lateralis

Mollusca is the second largest animal phylum and represents one of the most evolutionarily successful animal groups. Mulinia lateralis, a small bivalve, is a promising model organism to facilitate studies of mollusc development. However, because of the lack of published genomic and transcriptomic resources, integrated research on the formation of larval shells in this species, which is a representative developmental process of molluscs and of great importance for larva survival, is hindered. In this study, the blastula, gastrula, trochophore larva, and D-shaped larva of M. lateralis were utilized for generating a comprehensive full-length transcriptome through Pacific BioSciences (PacBio) isoform sequencing (Iso-seq) and Illumina RNA-Seq. A total of 238,919 full-length transcripts with an average length of 3,267 bp and 121,424 annotated genes were obtained. Illumina RNA-Seq data analysis showed that 4,512, 10,637, and 17,829 differentially expressed genes (DEGs) were obtained between the two adjacent developmental stages. Functional annotation and enrichment analysis revealed the specific function of genes in shell biomineralization during different developmental stages. Twelve genes that may be involved in the formation of the larval shell of M. lateralis were identified, including insoluble shell matrix protein-encoding gene 1 (ISMP1), ISMP2, ISMP5, chitin synthase, tyrosinase, chitin-binding protein, collagen and pu14 involved in shell matrix deposition, and carbonic anhydrase, solute carrier family 4 member 8 (slc4a8), EF-hand, and a calmodulin coding gene C-2442 participated in ion transportation. In addition, calcium ion binding function, calcium signaling pathway, and endocrine and other factor-regulated calcium reabsorption pathways were significantly enriched. Weighted gene correlation network analysis (WGCNA) identified two modules related to biomineralization and larval shell formation, and slc4a8 and ring finger protein 41 (rnf41) were key hub genes that may be involved in this process. Moreover, it could be implied that the process of ion transport occurs earlier than the deposition of the shell matrix. This work provided a clear view of the transcriptome for M. lateralis and will be valuable in elucidating the mechanisms of larval shell formation as well as other developmental processes in molluscs

Social Memory and the Resilience of Communities Affected by Land Degradation

Based on evidence collected in 22 village communities from nine study sites situated in Spain, Italy, Greece, Morocco and China, this study analyses the complex interlinkages between social memory, community resilience and land degradation. Social memory is seen as an important explanation regarding the ability of a local community to manage and cope with land degradation. Emphasis is placed on the importance of three components of social memory – rites, traditions and social learning processes – for shaping community resilience in coping with land degradation processes. The study argues that, although there are subtle differences between the 22 village communities, the loss of social memory and learning pathways associated with managing land degradation is emerging as a critical factor constraining stakeholders from effectively responding to land degradation issue

A novel CpG-methylation-based nomogram predicts survival in colorectal cancer

Aberrant DNA methylation is significantly associated with the prognosis of patients with colorectal cancer (CRC). Therefore, the aim of this study was to develop a CpG-methylation-based nomogram for prognostic prediction in CRC. First, 378 CRC patients with methylation data from The Cancer Genome Atlas were randomly divided into training cohort (n = 249) and test cohort (n = 129). A multistep screening strategy was performed to identify six CpG sites that were significantly associated with overall survival in the training cohort. Then, Cox regression modelling was performed to construct a prognostic signature based on the candidate CpG sites. The six-CpG signature successfully separated patients into high-risk and low-risk groups in both training and test cohorts, and its performance was superior to that of previously published methylation markers (P < 0.05). Furthermore, we established a prognostic nomogram incorporating this signature, TNM stage, and age. The nomogram exhibited better prediction for overall survival in comparison with the three independent prognostic factors in the training cohort (C-index: 0.798 vs 0.620 to 0.737; P < 0.001). In the test cohort, the performance of nomogram was also superior to that of the three independent prognostic factors (C-index: 0.715 vs 0.590 to 0.665; P < 0.05). Meanwhile, the calibration curves for survival probability showed good agreement between prediction by nomogram and actual observation in both training and test cohorts. Together, the present study provides a novel CpG-methylation-based nomogram as a promising predictor for overall survival of CRC patients, which may help improve decision-making regarding the personalized treatments of patients with CRC

Genetic and biological characterization of H9N2 avian influenza viruses isolated in China from 2011 to 2014.

The genotypes of the H9N2 avian influenza viruses have changed since 2013 when almost all H9N2 viruses circulating in chickens in China were genotype 57 (G57) with the fittest lineage of each gene. To characterize the H9N2 variant viruses from 2011 to 2014, 28 H9N2 influenza viruses were isolated from live poultry markets in China from 2011-2014 and were analyzed by genetic and biological characterization. Our findings showed that 16 residues that changed antigenicity, two potential N-linked glycosylation sites, and one amino acid in the receptor binding site of the HA protein changed significantly from 2011-2014. Moreover, the HA and NA genes in the phylogenetic tree were mainly clustered into two independent branches, A and B, based on the year of isolation. H9N2 virus internal genes were related to those from the human-infected avian influenza viruses H5N1, H7N9, and H10N8. In particular, the NS gene in the phylogenetic tree revealed genetic divergence of the virus gene into three branches labeled A, B, and C, which were related to the H9N2, H10N8, and H7N9 viruses, respectively. Additionally, the isolates also showed varying levels of infection and airborne transmission. These results indicated that the H9N2 virus had undergone an adaptive evolution and variation from 2011-2014

Identification and validation of the reference genes in the echiuran worm Urechis unicinctus based on transcriptome data

Abstract Background Real-time quantitative PCR (RT-qPCR) is a crucial and widely used method for gene expression analysis. Selecting suitable reference genes is extremely important for the accuracy of RT-qPCR results. Commonly used reference genes are not always stable in various organisms or under different environmental conditions. With the increasing application of high-throughput sequencing, transcriptome analysis has become an effective method for identifying novel stable reference genes. Results In this study, we identified candidate reference genes based on transcriptome data covering embryos and larvae of early development, normal adult tissues, and the hindgut under sulfide stress using the coefficient of variation (CV) method in the echiuran Urechis unicinctus, resulting in 6834 (15.82%), 7110 (16.85%) and 13880 (35.87%) candidate reference genes, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that the candidate reference genes were significantly enriched in cellular metabolic process, protein metabolic process and ribosome in early development and normal adult tissues as well as in cellular localization and endocytosis in the hindgut under sulfide stress. Subsequently, ten genes including five new candidate reference genes and five commonly used reference genes, were validated by RT-qPCR. The expression stability of the ten genes was analyzed using four methods (geNorm, NormFinder, BestKeeper, and ∆Ct). The comprehensive results indicated that the new candidate reference genes were more stable than most commonly used reference genes. The commonly used ACTB was the most unstable gene. The candidate reference genes STX12, EHMT1, and LYAG were the most stable genes in early development, normal adult tissues, and hindgut under sulfide stress, respectively. The log2(TPM) of the transcriptome data was significantly negatively correlated with the Ct values of RT-qPCR (Ct =  − 0.5405 log2(TPM) + 34.51), which made it possible to estimate the Ct value before RT-qPCR using transcriptome data. Conclusion Our study is the first to select reference genes for RT-qPCR from transcriptome data in Echiura and provides important information for future gene expression studies in U. unicinctus

Amino acid changes at key sites on the HA protein from H9N2 viruses from 2010 to 2015.

<p>a) The percentage of three potential glycosylation sites, including 145NGTS148, 218NRTF221, and 313NCSK316, was quantified by comparison with approximately 1100 H9N2 HA sequences deposited in GenBank from 2010 to 2015. b) The percentage of mutations at position 198 was quantified by comparison with approximately 1100 H9N2 HA sequences deposited in GenBank from 2010 to 2015. c) The percentage of mutations at positions 234–235 at the right-edge receptor-binding pocket were quantified by comparison with approximately 1100 H9N2 HA sequences deposited in GenBank from 2010 to 2015. d) The percentage of mutations at position 334–335 in the cleavage sites were quantified by comparison with approximately 1100 H9N2 HA sequences deposited in GenBank from 2010 to 2015.</p