Genes & Genomics

Pre-labelled oligo probe-FISH karyotype analyses of four Araliaceae species using rDNA and telomeric repeat Abstract Background The family Araliaceae contains many medicinal species including ginseng of which the whole genome sequencing analyses have been going on these days. Objective To characterize the chromosomal distribution of 5S and 45S rDNAs and telomeric repeat in four ginseng related species of Aralia elata (Miq.) Seem., Dendropanax morbiferus H. Lév., Eleutherococcus sessiliflorus (Rupr. Et Maxim.) Seem., Kalopanax septemlobus (Thunb. ex A.Murr.) Koidz. Method Pre-labelled oligoprobe (PLOP)-fluorescence in situ hybridization (FISH) was carried out. Results The chromosome number of A. elata was 2n = 24, whereas that of the other three species of D. morbiferus, E. sessiliflorus, and K. septemlobus was 2n = 48, corresponding to diploid and tetraploid, respectively, based on the basic chromosome number x = 12 in Araliaceae. In all four species, one pair of 5S signals were detected in the proximal regions of the short arms of chromosome 3, whereas in K. septemlobus, the 5S rDNA signals localized in the subtelomeric region of short arm of chromosome 3, while all the 45S rDNA signals localized at the paracentromeric region of the short arm of chromosome 1. And the telomeric repeat signals were detected at the telomeric region of both short and long arms of most chromosomes. Conclusion The PLOP-FISH was very effective compared with conventional FISH method. These results provide useful comparative cytogenetic information to better understand the genome structure of each species and will be useful to trace the history of ginseng genomic constitution.

Comparative transcriptome analysis of salt-sensitive and salt-tolerant maize reveals potential mechanisms to enhance salt resistance Abstract Background Salt stress is a devastating environmental stress that causes plant growth inhibition and yield reduction. Objective The identification of salt-tolerant genes brings hope for the generation of salinity-tolerant crop plants through molecular breeding. Methods In this study, one salt-sensitive and one salt-tolerant maize inbred line were screened from 242 maize inbred lines. Reactive oxygen species (ROS)-related enzyme activities were detected and salt-responsive comparative transcriptome analysis was performed for control and 220 mM NaCl treated maize leaves. Results Salt-tolerant maize inbred line (L87) showed higher ROS-related enzyme (SOD, POD, APX and CAT) activities and accumulated relatively lower levels of ROS under salt stress. Of the total DEGs, 1856 upregulated DEGs were specific to L87, including stress tolerance-related members of the 70kDa family of heat shock proteins (Hsp70s) and aquaporins. The DEGs involved in the abscisic acid (ABA), ethylene, jasmonic acid (JA) and salicylic acid (SA) signal transduction pathways may determine the difference in salt tolerance between the two varieties, especially one central component SnRK2, that positively regulates ABA signaling and was only upregulated in L87. Analysis of DEGs related to ROS scavenging showed that some peroxidase (POD), glutathione S-transferase (GST), catalase (CAT) and superoxide dismutase (SOD) genes specific to L87 probably enhanced its salt tolerance. The analysis of differentially expressed transcription factors (TFs) suggested that WRKY TFs could contribute to the difference in salt tolerance between the two maize lines. Conclusion Compared with Salt-sensitive maize inbred line (L29), L87 exhibits specific regulatory mechanisms related to salt tolerance, including plant hormone interactions, ROS scavenging and the regulation of TFs. Our study identifies new candidate genes that may regulate maize tolerance to salt stress and provides useful information for breeding maize with high salt resistance.

Pathogenic potential of non-typhoidal Salmonella serovars isolated from aquatic environments in Mexico Abstract Background River water has been implicated as a source of non-typhoidal Salmonella (NTS) serovars in Mexico. Objective To dissect the molecular pathogenesis and defense strategies of seven NTS strains isolated from river water in Mexico. Methods The genome of Salmonella serovars Give, Pomona, Kedougou, Stanley, Oranienburg, Sandiego, and Muenchen were sequenced using the whole-genome shotgun methodology in the Illumina Miseq platform. The genoma annotation and evolutionary analyses were conducted in the RAST and FigTree servers, respectively. The MLST was performed using the SRST2 tool and the comparisons between strains were clustered and visualized using the Gview server. Experimental virulence assay was included to evaluate the pathogenic potential of strains. Results We report seven high-quality draft genomes, ranging from ~ 4.61 to ~ 5.12 Mb, with a median G + C value, coding DNA sequence, and protein values of 52.1%, 4697 bp, and 4,589 bp, respectively. The NTS serovars presented with an open pan-genome, offering novel genetic content. Each NTS serovar had an indistinguishable virulotype with a core genome (352 virulence genes) closely associated with Salmonella pathogenicity; 13 genes were characterized as serotype specific, which could explain differences in pathogenicity. All strains maintained highly conserved genetic content regarding the Salmonella pathogenicity islands (1–5) (86.9–100%), fimbriae (84.6%), and hypermutation (100%) genes. Adherence and invasion capacity were confirmed among NTS strains in Caco-2 cells. Conclusion Our results demonstrated the arsenal of virulence and defense molecular factors harbored on NTS serovars and highlight that environmental NTS strains are waterborne pathogens worthy of attention.

Evidence for relaxed selection of mitogenome in rapid-flow cyprinids Abstract Background Hypoxia adaptation is developed in many fish species, which helped them to habitat most of water bodies. However, fishes living under high oxygen concentration may lose this feature. Rapid flows provide high level and stable dissolved oxygen, which facilitate organism's oxygen supply and energy production. Previous studies showed that fish species from rapid-flow habitats exhibited lower hypoxia tolerance compared with fish from intermediate- and slow-flow habitats. Mitochondrial genomes code 13 key components in oxidative phosphorylation pathway; these genes may be under relaxed selection in rapid-flow species. Objectives The primary objectives of this study is to investigate the evolutionary patterns of the 13 mitochondrial OXPHOS genes among nine cyprinids from different water bodies and to test the hypotheses that mitochondrial OXPHOS genes may experience relaxed selection in rapid-flow habitats. Methods We classified nine cyprinid fish species into three groups based on their habitats: rapid-flow, intermediate-flow and slow-flow. To detect relaxed selections, we investigated the 13 protein-coding genes with codon evolution programs RELAX; to estimate evolutionary rates among the cyprinids, free-ratio model in Codeml program was applied; Branch-site models were applied to detect positive selection sites. The polymorphisms of homologous sites were evaluated with PROVEAN program and projected to 3D structure prediction of the proteins using SWISS-MODEL. Results We found that nine out of the 13 genes are under relaxed selection in rapid-flow species. Furthermore, dN, dS and dN/dS are relatively increased when compared with those of intermediate-flow species. More amino acid polymorphic sites are presented in rapid-flow species than in intermediate- and slow-flow species. Furthermore, rapid-flow species had more deleterious substitutions than other groups. 3D structure prediction of these proteins and projection of the polymorphic sites indicated that these sites were randomly distributed, suggesting relaxed functional constraints of these proteins in rapid-flow species. Conclusion Our results suggest that mitochondrial genes are under relaxed selection in rapid-flow cyprinids.

Deep sequencing reveals microRNA signature is altered in the rat epididymis following bilateral castration Abstract Background In the epididymis of bilateral castrated male rat, gene expression profile changed significantly. However, up to date, no study has investigated how these genes were regulated by microRNAs (miRNAs). Objective We investigated the alterations in the miRNA signature of the epididymis from sham-operated and bilaterally castrated rats. Methods By employing deep sequencing technology and qPCR, the global alterations of epididymal miRNA signature between sham-operated (Con-EP library) and bilaterally castrated rats (Cas-EP library) were explored. MiRNA-target interaction networks were annotated by GO and KEGG enrichment. Results We identified 313 and 306 known miRNAs as well as 152 and 114 novel miRNAs in the Con-EP and Cas-EP libraries, respectively. 59 miRNAs were differentially expressed, including 24 up-regulated and 35 down-regulated miRNAs, among which two up-regulated and three down-regulated ones were validated using qPCR. The expression of these miRNAs in the epididymides of rats at different postnatal ages showed regular changes from birth to adult, suggesting they were androgen-regulated. GO analysis showed that many of the miRNA targets were enriched in metabolic processes. KEGG analysis demonstrated that the targets mainly participated in the mitogen-activated protein kinase (MAPK) pathway. Moreover, 3 and 6 functional modules were detected among the up- and down-regulated miRNA target interaction networks, respectively, and these modules were involved in various biological processes. Conclusion This study represents the first systematic investigation of alterations in the miRNA signature of the epididymis from bilaterally castrated rats and will provide useful resources for functional studies of the miRNAs in the male reproductive system.

Evolutionary and functional implications of 3′ untranslated region length of mRNAs by comprehensive investigation among four taxonomically diverse metazoan species Abstract Background In eukaryotic organisms, it has been well acknowledged that 3′ untranslated regions (3′ UTRs) of mRNA are actively involved in post-transcriptional regulations of gene expression. Although both shortening and lengthening of 3′ UTRs of specific candidate genes were explicitly documented to have functional consequences, landscape of 3′ UTR lengths in relation to evolutionary dynamics and biological meanings remains to be elucidated when large-scale data become available. Objectives The primary objective of this study was to revealed different inter- and intra-species patterns on length distribution of 3′ UTRs in comparison with 5′ UTRs and coding regions. Methods In the present study, we investigated 3′ UTR lengths in a highly curated set of 57,135 mRNA sequences among four well-studied and taxonomically diverse metazoan species (fruit fly, zebrafish, mouse and human). Results The average length ratio of 3′–5′ UTRs considerably increased from fruit fly (twofold) to human (fivefold). Moreover, genes can be characterized by the obviously different patterns of evolutionary change on 3′ UTR lengths. By utilizing the Gene Ontology annotations, genes with differential lengths of 3′ UTRs were suggested to have the divergent functional implications. In human, we further revealed that ubiquitously transcribed genes had higher median lengths of 3′ UTRs than the genes of tissue-restricted expressions. Conclusion We conducted a comprehensive analysis and provided an overview regarding 3′ UTRs biology of mRNAs in animals, whereas the mechanistic explanations of 3′ UTRs length variation in correlation to regulation of gene expression still remain to be further studied.

A comprehensive analysis of the Baboon-specific full-length LINE-1 retrotransposons Abstract Background Long interspersed elements-1 (LINE-1s or L1s) and Alu elements are most successful retrotransposons that have generated genetic diversity and genomic fluidity in the primate genome. They account for ~ 27.7% of the primate genome. Interestingly, a previous study has shown that the retrotransposition rate of Alu elements is nine times higher in baboons than in humans. Objective The expansion of Alu copies could be dependent on the activity of L1-encoded proteins. Thus, we aimed to investigate full-length baboon-specific L1s and characterize structurally and functionally intact baboon-specific L1s (ORF1p/ORF2p and ORF2p only) that could induce trans-mobilization of Alu elements in the baboon genome. Results A total of 673 baboon-specific L1 candidates (> 4 kb) were identified through the comparative genomic analysis. Applying the baboon-specific correction value obtained from the experimental validation, it demonstrated that approximately 446 baboon-specific L1s (> 4 kb) were present in the baboon reference genome (papAnu2). In addition, we observed phylogenetic relationship of the baboon-specific L1s through the neighbor-joining method and they diverged from the L1PA6 consensus sequence. Finally, we identified 36 full-length baboon-specific L1s that were intact both ORF1p and ORF2p. Conclusion The number of baboon-specific full-length L1s is fewer than the number of human-specific full-length L1s. Therefore, there is possibility that the "L1 master gene" or "L1 source gene" is more abundant in the baboon genome, or that in trans retrotransposition activity of baboon-specific L1s is relatively stronger than in the other genomes.

Long noncoding RNA UCA1 inhibits ischaemia/reperfusion injury induced cardiomyocytes apoptosis via suppression of endoplasmic reticulum stress Abstract Background Ischemia heart disease is one of the major causes of death worldwide which often associated with tissue infarction and limit the recovery of function. Multiple factors involved in the I/R-induced cardiomyocyte dysfunction which were consistent with a role of oxidative stress and altered endothelium-dependent responses. However, the pathogenic mechanisms in I/R injury remain unclear. Materials and methods The H9C2 cells were in the ischaemia/reperfusion (I/R) condition. After I/R, the cells were transfected with or without adenovirus-urothelial carcinoma associated 1(Ad-UCA1). Then qRT-PCR analysis was performed to quantify mRNA expression of different treatment groups. Cell apoptosis rate was assessed using flow cytometry and ER stress biomarker expression were measured by immunoblotting. Intracellular and mitochondrial ROS generation were assayed by fluorescence microscope after staining with the DCFDA or MitoSOX. Results I/R conditions trigger lncRNAs UCA1 expression, cellular and mitochondria ROS production, resulting in cell apoptosis through the induction of oxidative and ER stress. Overexpression of UCA1 protects H9C2 cells from I/R-induced ER stress and cell apoptosis. Moreover, UCA1 might be a potential regulator in the protective effect of I/R‑induced oxidative stress and mitochondria dysfunction. Subsequently, ER stress inhibitor attenuated the effect of siUCA1 induced injury in H9C2 cells. Conclusion The expression of UCA1 against I/R induced oxidative stress and mitochondria dysfunction via suppression of endoplasmic reticulum stress. UCA1 might be a biomarker to improved diagnosis of I/R injury.

Transcriptome-wide identification of miRNA targets and a TAS3-homologous gene in Populus by degradome sequencing Abstract Background Degradome sequencing has been applied to identify miRNA-directed mRNA cleavage and understand the biological function of miRNAs and their target genes in plants defense to stress. miRNAs involved in the response to cold stress have been identified in Populus, however, there are few reports about the validated targets of miRNAs in Populus under cold stress. Objectives The primary objective of this investigation was to globally identify and validate the targets of the miRNAs and regulatory components in Populus under cold stress. Methods Populus plantlets grown in vitro were treated with cold (4 °C for 8 h) and total RNA was extracted using Trizol reagent. Approximately 200 µg total RNA was used for the construction of the degradome library, and degradome sequencing was conducted on an Illumina HiSeq 2000. The sequences were mapped to Populus genome using SOAP 2.0 and then were collected for degradome analysis. Additionally, trans-acting siRNA sequences from transacting siRNA gene 3 sequences and mature miRNAs cleaved from precursor miRNAs of Populus were analyzed. 5′ RNA ligase-mediated-RACE (5′-RACE) were further conducted. Results 80 genes were experimentally determined to be the target of 51 unique miRNAs, including three down-regulated miRNAs (pto-miR156k, pto-miR169i-m, and pto-miR394a-5p/b-5p) and two up-regulated miRNAs (pto-miR167a-d and pto-miR167f/g). The specificity and diversity of cleavage sites of miRNA targets were validated through 5′-RACE experiment and the results were similar with that of degradome sequencing, further supporting the empirical cleavage of miRNAs on targets in vivo in Populus. Interestingly, the TAS-homologous gene pto-TAS3 (EF146176.1) was identified and 11 potential ta-siRNAs [D1(+)–D11(+)] and their possible biogenesis sites within the pto-TAS3 transcript sequence were predicted in Populus. In addition, the biosynthesis of miRNA from precursor miRNA (pre-miRNA) was also validated through the detection of a total of 17 pre-miRNAs. Conclusion Our investigation expands the application of degradome sequencing for evaluating miRNA regulatory elements and evidence of the miRNA synthesis process, and provides empirical evidence of bona fide cleavage of target genes by miRNAs in Populus, which might be used for the research of miRNA-mediated regulation mechanism and molecular improvement of resistance to cold stress.

Sugar metabolism as input signals and fuel for leaf senescence Abstract Senescence in plants is an active and acquired developmental process that occurs at the last developmental stage during the life cycle of a plant. Leaf senescence is a relatively slow process, which is characterized by loss of photosynthetic activity and breakdown of macromolecules, to compensate for reduced energy production. Sugars, major photosynthetic assimilates, are key substrates required for cellular respiration to produce intermediate sources of energy and reducing power, which are known to be essential for the maintenance of cellular processes during senescence. In addition, sugars play roles as signaling molecules to facilitate a wide range of developmental processes as metabolic sensors. However, the roles of sugar during the entire period of senescence remain fragmentary. The purpose of the present review was to examine and explore changes in production, sources, and functions of sugars during leaf senescence. Further, the review explores the current state of knowledge on how sugars mediate the onset or progression of leaf senescence. Progress in the area would facilitate the determination of more sophisticated ways of manipulating the senescence process in plants and offer insights that guide efforts to maintain nutrients in leafy plants during postharvest storage.

Alexandros Sfakianakis
Anapafseos 5 . Agios Nikolaos
Crete.Greece.72100
2841026182

6948891480

alsfakia@gmail.com