Comparative genomics of seven genomes of genus Idiomarina reveals important halo adaptations and genes for stress response

The genus Idiomarina consists of halophilic and/or haloalkaliphilic organisms. We compared the complete genomes of seven strains of the genus Idiomarina to investigate its adaptation to saline environment. A total of 1,313 core genes related to salinity tolerance, stress response, antibiotic resistance genes, virulence factors, and drug targets were found. Comparative genomics revealed various genes involved in halo adaptations of these organisms, including transporters and influx or efflux systems for elements such as Fe, Cu, Zn, Pb, and Cd. In agreement with their isolation sources (such as hydrothermal vents and marine sediments) and environments abundant in heavy metals, various resistance proteins and transporters associated with metal tolerance were also identified. These included copper resistance proteins, zinc uptake transcriptional repressor Zur, MerC domain-containing protein, Cd(II)/Pb(II)-responsive transcriptional regulator, Co/Zn/Cd efflux system protein, and mercuric transporter. Interestingly, we observed that the carbohydrate metabolism pathways were incomplete in all the strains and transporters used for absorption of small sugars were also not found in them. Also, the presence of higher proportion of genes involved in protein metabolism than carbohydrate metabolism indicates that proteinaceous substrates act as the major food substrates for these bacterial strains than carbohydrates. Genomic islands were detected in some species, highlighting the role of horizontal gene transfer for acquisition in novel genes. Genomic rearrangements in terms of partially palindromic regions were detected in all strains. To our knowledge, this is the first comprehensive comparative genomics study among the genus Idiomarina revealing unique genomic features within bacterial species inhabiting different ecological niches.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03887-3.

Integrative Analysis of Core Genes and Biological Process Involved in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a common gynecological endocrine disordered disease, affecting the function of the ovaries in women of reproductive age. However, there are limited curative therapies for PCOS due to lack of reliable candidates. Hence, this study aimed to identify hub pathogenic genes and potential therapeutic targets for PCOS using bioinformatics tools. We obtained the expression profiles of 29 PCOS samples and 24 normal samples from three Gene Expression Omnibus (GEO) datasets. Then, the differentially expressed genes (DEGs) were screened, which were subjected to functional enrichment analyses. Moreover, we found 30 ferroptosis-related genes out of the 89 DEGs. Among the top 10 significant ferroptosis-related DEGs, 8 genes showed good predictive performance. We constructed interaction network of top three ferroptosis-related DEGs (SLC38A1, ACO1, DDIT3). Finally, real-time PCR was performed to test the relative expression of these genes. In conclusions, we have identified ferroptosis-related DEGs as core genes and potential therapeutic targets of PCOS based on comprehensive bioinformatics analysis. The findings are conducive to understanding of the pathogenesis of PCOS and paving the way towards curative therapies.

Comparative genomic analysis reveals new evidence of genus boundary for family Iridoviridae and explores qualified hallmark genes

Members of the family Iridoviridae (iridovirids) are globally distributed and trigger adverse economic and ecological impacts on aquaculture and wildlife. Iridovirids taxonomy has previously been studied based on a limited number of genomes, but this is not suitable for the current and future virological studies as more iridovirids are emerging. In our study, 57 representative iridovirids genomes were selected from a total of 179 whole genomes available on NCBI. Then 18 core genes were screened out for members of the family Iridoviridae. Average amino acid sequence identity (AAI) analysis indicated that a cut-off value of 70% is more suitable for the current iridovirids genome database than ICTV-defined 50% threshold to better clarify viral genus boundaries. In addition, more subgroups were divided at genus level with the AAI threshold of 70%. This observation was further confirmed by genomic synteny analysis, codon usage preference analysis, genome GC content and length analysis, and phylogenic analysis. According to the pairwise comparison analysis of core genes, 9 hallmark genes were screened out to conduct preliminary identification and investigation at the genus level of iridovirids in a more convenient and economical manner.

Transcriptomic analysis of tuberous root in two sweet potato varieties reveals the important genes and regulatory pathways in tuberous root development

Background

Tuberous root formation and development is a complex process in sweet potato, which is regulated by multiple genes and environmental factors. However, the regulatory mechanism of tuberous root development is unclear.

Results

In this study, the transcriptome of fibrous roots (R0) and tuberous roots in three developmental stages (Rl, R2, R3) were analyzed in two sweet potato varieties, GJS-8 and XGH. A total of 22,914 and 24,446 differentially expressed genes (DEGs) were identified in GJS-8 and XGH respectively, 15,920 differential genes were shared by GJS-8 and XGH. KEGG pathway enrichment analysis showed that the DEGs shared by GJS-8 and XGH were mainly involved in “plant hormone signal transduction” “starch and sucrose metabolism” and “MAPK signal transduction”. Trihelix transcription factor (Tai6.25300) was found to be closely related to tuberous root enlargement by the comprehensive analysis of these DEGs and weighted gene co-expression network analysis (WGCNA).

Conclusion

A hypothetical model of genetic regulatory network for tuberous root development of sweet potato is proposed, which emphasizes that some specific signal transduction pathways like “plant hormone signal transduction” “Ca²⁺signal” “MAPK signal transduction” and metabolic processes including “starch and sucrose metabolism” and “cell cycle and cell wall metabolism” are related to tuberous root development in sweet potato. These results provide new insights into the molecular mechanism of tuberous root development in sweet potato.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08670-x.

A new and effective genes-based method for phylogenetic analysis of Klebsiella pneumoniae

The exponential increase in the number of genomes deposited in public databases can help us gain a more holistic understanding of the phylogeny and epidemiology of Klebsiella pneumoniae. However, inferring the evolutionary relationships of K. pneumoniae based on big genomic data is challenging for existing methods. In this study, core genes of K. pneumoniae were determined and analysed in terms of differences in GC content, mutation rate, size, and potential functions. We then developed a stable genes-based method for big data analysis and compared it with existing methods. Our new method achieved a higher resolution phylogenetic analysis of K. pneumoniae. Using this genes-based method, we explored global phylogenetic relationships based on a public database of nearly 953 genomes. The results provide useful information to facilitate the phylogenetic and epidemiological analysis of K. pneumoniae, and the findings are relevant for security applications.

Genomic analysis of Poxviridae and exploring qualified gene sequences for phylogenetics

The members of the Poxviridae family are globally distributed all over the world and can cause infectious diseases. Although genome sequences are publicly available for representative isolates of all genera, studies on the criteria for genome-based classification within the Poxviridae family have rarely been reported. In our study, 60 Poxviridae genomes were re-annotated using Prokka. By using BLAST filtration and MCScanX, synteny and similarity of whole genomic amino acid sequences were visualized. According to the analysis pattern, the Chordopoxvirinae and Entomopoxvirinae subfamilies can be subdivided into five and two categories respectively, which is consistent with the phylogenetic tree constructed based on whole genomic amino acid sequences and Poxvirus core genes. Finally, four genes (Early transcription factor, DNA-directed RNA polymerase, RNA polymerase-associated transcription-specificity factor and DNA-dependent RNA polymerase) were selected from Poxvirus core genes by substitution saturation analysis and phylogenetic tree verification. Phylogenetic trees constructed based on single gene and concatenated sequences of the four selected genes showed that the classification of subgroups was consistent with the phylogenetic trees based on genome. Conclusion: a new method based on the similarity of whole genomic amino acid sequences was proposed for Poxviridae taxon demarcation, and the use of the four selected qualified genes will help make phylogenic identification of newly discovered Poxviridae isolates more convenient and accurate.

Bioinformatics analysis of sequential gene expression profiling after skin and skeletal muscle wound in mice

It is of great value to use bioinformatics methods to screen the core differentially expressed genes (DEGs) at different times after mouse skin and skeletal muscle wound, and to explore the relationship between them and the wound age. To this end, we downloaded the gene expression profiles of GSE140517 and GSE23006 from the NCBI-GEO gene database, used GEO2R online tools and Venn diagrams to screen out DEGs at different times and common-DEGs. The Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) channel analysis were carried out through the DAVID website respectively. Use STRING tool to build a Protein-protein Interaction (PPI) network, and use Cytoscape software to screen out core DEGs. The results showed that 13, 53, 43 and 13 core DEGs were screened out in the 6 h, 12 h, 24 h and common-DEGs group after wound. There were 7 core DEGs (Cxcl2, Cxcl3, Il1b, Ptgs2, Cxcl1, Timp1, Ccl3) in both the different time point and the common DEGs group. Meanwhile, there are 1 core DEGs (Ccl4) specifically expressed in the 6 h, 29 specifically expressed core DEGs (Isg20, Rtp4, Fcgr1, Ifi44, Trim30a, etc.) in the 12 h, and 18 specifically expressed core DEGs (Ccr7, Myd88, Igsf6, Ccr2, Gpsm3, etc.) in the 24 h, there are 6 core DEGs (Ccl4, Ccl7, Saa3, Cxcl5, Ccl2, Lcn2) specifically expressed in the common-DEGs group. The results of GO and KEGG analysis showed that the deterioration and exudation of the inflammatory response were the main cause at 6 h after wound. In addition to inflammation at 12 h and 24 h, the systemic immune response against viral and bacterial infections also gradually increased. In summary, the core DEGs selected in this study have combined characteristics, consistent with the healing function at the corresponding time point, and they are also has specificity and correlation with wound age. Therefore, by detecting the changes in the expression of co-expressed core DEGs at different times after wound, as well as detecting specific expressed DEGs at a specific time point or a specific period of time, it is very promising to provide help for the wound age estimation. However, limited by the GSE140517 gene expression profile in the database, only the difference in gene expression at different times within 24 h after wound was explored, and the research on the late wound age still needs to be further in-depth.

Hongsoonwoonella zoysiae gen. nov., sp. nov., a new member of the family Stappiaceae isolated from a tidal mudflat

A Gram stain-negative bacterial strain, designated SY4-7^T, was isolated from rhizosphere mudflat of a halophyte (Zoysia sinica) collected around Seonyu Island, Republic of Korea. Cells of the organism were strictly aerobic, non-sporulating, non-motile rods and grew at 20-42 °C, pH 6-8 and 1-6% (w/v) NaCl. The 16S rRNA gene-based phylogenetic analyses revealed that strain SY4-7^T formed an independent cluster separated from the recognized genera of the family Stappiaceae, which was also supported by phylogenomic analysis-based 92-core gene sequences. The type stains of the phylogenetically closest relatives were Stappia indica (95.6% sequence similarity), Stappia stellulata (95.1%) and Roseibium hamelinense (95.1%). The isoprenoid quinone was Q-10. The polar lipids consisted of phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, three unidentified aminophospholipids, an unidentified phosphoglycolipid, an unidentified aminolipid, two unidentified phospholipids and an unidentified lipid. The major cellular fatty acids are C_18:1ω7c and C_19:1 cyclo ω8c. The G + C content of the genomic DNA is 60.7%. Discrimination of the organism from all the recognized genera of the family Stappiaceae was apparent by the chemotaxonomic and phylogenetic features. Based on the results presented here, strain SY4-7^T (= KCTC 72226^T = NBRC 113902^T) represents a novel species of a new genus in the family Stappiaceae, for which the name Hongsoonwoonella zoysiae sp. nov. is proposed.

Identification of two core genes in glioblastomas with different isocitrate dehydrogenase mutation status

Glioblastoma (GBM) is one of the most common malignancies of the central nervous system, and the Isocitrate Dehydrogenase (IDH) mutation status of GBM has been recognized as a critical prognostic indicator. However, the molecular mechanism underlying the GBM with different IDH mutation status is still not unclear. In this study, a total of 353 DEGs including 207 up-regulated and 146 down-regulated were screened from multiple GBM data sets. Moreover, the biological processes and pathways enriched by DEGs were mainly associated with tumor progression, especially invasion and migration. Then, eight hub genes, including SDC4, SERPINE1, TNC, THBS1, COL1A1, CXCL8, TIMP1 and VEGFA, were selected from a PPI network. Finally, core genes, SERPINE1 and TIMP1, were identified from hub genes by survival analysis and sample validation. Overall, in this study, we revealed underlying molecular mechanisms in GBMs with different IDH mutation status and identified core genes that could be potential markers and targets for diagnosis and treatment of GBMs.

Pan-genomics of Ochrobactrum species from clinical and environmental origins reveals distinct populations and possible links

Ochrobactrum genus is comprised of soil-dwelling Gram-negative bacteria mainly reported for bioremediation of toxic compounds. Since last few years, mainly two species of this genus, O. intermedium and O. anthropi were documented for causing infections mostly in the immunocompromised patients. Despite such ubiquitous presence, study of adaptation in various niches is still lacking. Thus, to gain insights into the niche adaptation strategies, pan-genome analysis was carried out by comparing 67 genome sequences belonging to Ochrobactrum species. Pan-genome analysis revealed it is an open pan-genome indicative of the continuously evolving nature of the genus. The presence/absence of gene clusters also illustrated the unique presence of antibiotic efflux transporter genes and type IV secretion system genes in the clinical strains while the genes of solvent resistance and exporter pumps in the environmental strains. A phylogenomic investigation based on 75 core genes depicted better and robust phylogenetic resolution and topology than the 16S rRNA gene. To support the pan-genome analysis, individual genomes were also investigated for the mobile genetic elements (MGE), antibiotic resistance genes (ARG), metal resistance genes (MRG) and virulence factors (VF). The analysis revealed the presence of MGE, ARG, and MRG in all the strains which play an important role in the species evolution which is in agreement with the pan-genome analysis. The average nucleotide identity (ANI) based on the genetic relatedness between the Ochrobactrum species indicated a distinction between individual species. Interestingly, the ANI tool was able to classify the Ochrobactrum genomes to the species level which were assigned till the genus level on the NCBI database.

Identification of Flap endonuclease 1 as a potential core gene in hepatocellular carcinoma by integrated bioinformatics analysis

Hepatocellular carcinoma (HCC) is a common yet deadly form of malignant cancer. However, the specific mechanisms involved in HCC diagnosis have not yet fully elucidated. Herein, we screened four publically available Gene Expression Omnibus (GEO) expression profiles (GSE14520, GSE29721, GSE45267 and GSE60502), and used them to identify 409 differentially expressed genes (DEGs), including 142 and 267 up- and down-regulated genes, respectively. The DAVID database was used to look for functionally enriched pathways among DEGs, and the STRING database and Cytoscape platform were used to generate a protein-protein interaction (PPI) network for these DEGs. The cytoHubba plug-in was utilized to detect 185 hub genes, and three key clustering modules were constructed with the MCODE plug-in. Gene functional enrichment analyses of these three key clustering modules were further performed, and nine core genes including BIRC5, DLGAP5, DTL, FEN1, KIAA0101, KIF4A, MCM2, MKI67, and RFC4, were identified in the most critical cluster. Subsequently, the hierarchical clustering and expression of core genes in TCGA liver cancer tissues were analyzed using the UCSC Cancer Genomics Browser, and whether elevated core gene expression was linked to a poor prognosis in HCC patients was assessed using the GEPIA database. The PPI of the nine core genes revealed an interaction between FEN1, MCM2, RFC4, and BIRC5. Furthermore, the expression of FEN1 was positively correlated with that of three other core genes in TCGA liver cancer tissues. FEN1 expression in HCC and other tumor types was assessed with the FIREBROWSE and ONCOMINE databases, and results were verified in HCC samples and hepatoma cells. FEN1 levels were also positively correlated with tumor size, distant metastasis and vascular invasion. In conclusion, we identified nine core genes associated with HCC development, offering novel insight into HCC progression. In particular, the aberrantly elevated FEN1 may represent a potential biomarker for HCC diagnosis and treatment.

Expanding dynamics of the virulence-related gene variations in the toxigenic Vibrio cholerae serogroup O1

Background

Toxigenic Vibrio cholerae serogroup O1 is the causative pathogen in the sixth and seventh cholera pandemics. Cholera toxin is the major virulent factor but other virulence and virulence-related factors play certain roles in the pathogenesis and survival in the host. Along with the evolution of the epidemic strains, the virulence-related genes also experience variation, gain and loss, and lead to genetic divergence in different strains.

Results

In this study, we analyzed the virulence-related gene profiles in the toxigenic serogroup O1 strains isolated from 1923 to 2015, the genomes of which were publicly available. The virulence-related genes of the V. cholerae O1 strains were annotated based on the Virulence Factors Database (VFDB). An average of 230.1 virulence-related genes per strain were identified; significant differences in the average numbers were found between the classical and El Tor biotypes, and increasing trends in the number of virulence-related genes along with the isolation years were observed in the El Tor biotype strains. A total of 176 homologs of virulence-related genes were found from these strains, of which 25 belonged to the core genes, suggesting their conservative and necessary roles in V. cholerae pathogenesis. We described the diversities of the homologs by defining gene sequence type, and illustrated its association with gene duplication; we found that gene duplication clearly increased the complexity of the gene sequence types in the core virulence-related genes. In addition, we provided virulence-related gene profiles whose genetic characteristic depend on the isolation years from the view of gene gain and loss, variation, gene duplication and gene sequence type number.

Conclusions

Our study reveals the comprehensive variation dynamics of the virulence-related genes in toxigenic V. cholerae serogroup O1 during epidemics. The increasing trend for the virulence-related genes may suggest the evolutional advantage of strains by gaining virulence-related genes with diverse functional categories.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5725-y) contains supplementary material, which is available to authorized users.

A brief review of software tools for pangenomics

Since the proposal for pangenomic study, there have been a dozen software tools actively in use for pangenomic analysis. By the end of 2014, Panseq and the pan-genomes analysis pipeline (PGAP) ranked as the top two most popular packages according to cumulative citations of peer-reviewed scientific publications. The functions of the software packages and tools, albeit variable among them, include categorizing orthologous genes, calculating pangenomic profiles, integrating gene annotations, and constructing phylogenies. As epigenomic elements are being gradually revealed in prokaryotes, it is expected that pangenomic databases and toolkits have to be extended to handle information of detailed functional annotations for genes and non-protein-coding sequences including non-coding RNAs, insertion elements, and conserved structural elements. To develop better bioinformatic tools, user feedback and integration of novel features are both of essence.