Genome最新文献

The North American (NA) Atlantic salmon typically has 27 pairs of chromosomes, whereas the European (EU) subspecies typically has 29. We investigated within-family recombination within three previously identified chromosome rearrangements (Ssa01p/23, Ssa08/29, and Ssa26/28) in NA Atlantic salmon by creating high-density linkage maps using a custom 50K SNP chip developed for the Saint John River aquaculture strain. Linkage maps created for individual purebred and EU hybrid parents in 10 full-sibling families averaged 14 337 SNPs per cross, covering 43 033 SNPs from the 50K SNP chip. Chromosomal translocation Ssa01p/23 was fixed except in one hybrid female map. In contrast, fusion Ssa08/29 was present in maps in 4 out of 10 females and 8 out of 10 males, whereas fusion Ssa26/28 was present in maps in 6 out of 10 females and 8 out of 10 males. The orientation of Ssa08/29 differed from the previous map; the short arm of the metacentric Ssa08 was fused to the centromere of the acrocentric Ssa29. We detected large regions of recombination suppression in female maps at the fusion of Ssa08 to Ssa29. This suppression may reduce the impacts of aneuploidy resulting from pairing of fused and unfused chromosomes, thereby allowing the persistence of chromosomal polymorphisms in this population.

Macroptilium (Benth.) Urb. is a neotropical legume genus from the subtribe Phaseolinae. The investigated species present a stable chromosome number (2n = 22), but differ in their karyotype formulae, suggesting the presence of chromosome rearrangements. In this work, we comparatively analysed the karyotypes of six species (Macroptilium atropurpureum, Macroptilium bracteatum, Macroptilium erythroloma, Macroptilium gracile, Macroptilium lathyroides, and Macroptilium martii) from the two main clades that form the genus. Heterochromatin distribution was investigated with chromomycin A₃ (CMA)/4',6-diamidino-2-phenylindole (DAPI) staining and fluorescent in situ hybridization was used to localize the 5S and 35S ribosomal DNA (rDNA) sites. Single copy bacterial artificial chromosomes (BACs) previously mapped in the related genera Phaseolus L. and Vigna Savi were used to establish chromosome orthologies and to investigate possible rearrangements among species. CMA⁺/DAPI^- bands were observed, mostly associated with rDNA sites. Additional weak, pericentromeric bands were observed on several chromosomes. Although karyotypes were similar, species could be differentiated mainly by the number and position of the 5S and 35S rDNA sites. BAC markers demonstrated conserved synteny of the main rDNA sites on orthologous chromosomes 6 and 10, as previously observed for Phaseolus and Vigna. The karyotypes of the six species could be differentiated, shedding light on its karyotype evolution.

Genome size evolution is known to be related with transposable elements, yet such relation in incipient species remains poorly understood. For decades, the willistoni subgroup of Drosophila has been a model for evolutionary studies because of the different evolutionary stages and degrees of reproductive isolation its species present. Our main question here was how speciation influences genome size evolution and the fraction of repetitive elements, with a focus on transposable elements. We quantitatively compared the mobilome of four species and two subspecies belonging to this subgroup with their genome size, and performed comparative phylogenetic analyses. Our results showed that genome size and the fraction of repetitive elements evolved according to the evolutionary history of these species, but the content of transposable elements showed some discrepancies. Signals of recent transposition events were detected for different superfamilies. Their low genomic GC content suggests that in these species transposable element mobilization might be facilitated by relaxed natural selection. Additionally, a possible role of the superfamily DNA/TcMar-Tigger in the expansion of these genomes was also detected. We hypothesize that the undergoing process of speciation could be promoting the observed increase in the fraction of repetitive elements and, consequently, genome size.

1-Deoxy-d-xylulose-5-phosphate synthase and 1-deoxy-d-xylulose-5-phosphate reductoismerase are considered two key enzymes in the 2-C-methyl-d-erythritol-4-phosphate pathway of terpenoid biosynthesis and are related to the synthesis and accumulation of sesquiterpenoids. We cloned two DXS and DXR genes from Atractylodes lancea and analysed their expression in different tissues and in response to methyl jasmonate (MeJA). Subcellular localisation analysis revealed that the AlDXS and AlDXR1 proteins are located in the chloroplasts and cytoplasm, whereas AlDXR2 is only located in the chloroplasts. pET-AlDXS-28a and pGEX-AlDXR-4T-1 were expressed in Escherichia coli BL21(DE3) and BL21, respectively. Based on the abiotic stress analysis, the growth rate of the recombinant pGEX-AlDXR-4T-1 was higher than that of the control in HCl and NaOH. AlDXS exhibited the highest expression level in rhizomes of A. lancea from Hubei but was highest in leaves from Henan. In contrast, AlDXR showed maximum expression in the leaves of A. lancea from Hubei and Henan. Moreover, DXS and DXR gene expression, enzyme activities, and antioxidant enzyme activities oscillated in response to MeJA, with expression peaks appearing at different time points. Our findings indicated that the characterisation and function of AlDXS and AlDXR could be useful for further elucidating the functions of DXR and DXR genes in A. lancea.

Transposable elements (TEs) are DNA sequences that possess the ability to move from one genomic location to another. These sequences contribute to a significant fraction of the genomes of most eukaryotes and can impact their architecture and regulation. In this paper, we present the first data related to the identification and characterization of TEs present in the transcriptome of Anticarsia gemmatalis. Approximately, 835 transcripts showed significant similarity to TEs and (or) characteristic domains. Retrotransposons accounted for 71.2% (595 sequences) of the identified elements, while DNA transposons were less abundant, with 240 annotations (28.8%). TEs were classified into 30 superfamilies, with SINE3/5S and Gypsy being the most abundant. Based on the sequences of TEs found in the transcriptome, we were able to locate conserved regions in the chromosomes of this species. The analysis of differential expression of TEs in susceptible and resistant strains, challenged and not challenged with Bacillus thuringiensis (Bt) from in silico analysis, indicated that exposure to Bt can regulate the transcription of mobile genetic elements in the velvetbean caterpillar. Thus, these data contribute significantly to the knowledge of the structure and composition of these elements in the genome of this species, and suggest the role of stress on their expression.

Paenibacillus terrae NK3-4 is a plant growth-promoting rhizobacterium. In this study, the effects of NK3-4 on rice growth and gene transcription were determined. The results indicated that a seed soaking treatment and a pre-germination seed treatment using NK3-4 promoted rice growth, especially spraying rice seedlings with NK3-4 increased the root number and root length by 34.2% and 34.1%, respectively. Moreover, NK3-4 induced the differential transcription of genes annotated with gene ontology (GO) terms; the number of up-regulated genes was 4.38-times higher than the number of down-regulated genes. The NK3-4 treatment induced the differential transcription of genes in 1794 GO functional groups, with 1531 functional groups containing up-regulated genes. Specific growth-related genes up-regulated by NK3-4 are involved in biological processes, including responses to auxin, hormone biosynthesis, cellular component biogenesis, root system development, and other functions. Furthermore, stress resistance-related genes were up-regulated, some of which encode WRKYs, NPK1-related protein kinase, NPR1-like 4, CaM-like proteins, MYBs, ERFs, TIFYs, NACs, EL5s, PR1s, PR2, PR8, PODs, and PAD4. Considered together, these findings imply that NK3-4 may promote plant growth and enhance stress resistance by regulating gene expression, making it a potentially useful microbe for regulating rice growth and stress resistance.

C2H2-zinc finger (C2H2-ZF) genes are involved in various biological processes in plants including stress response; however, they lack characterization in Brassica napus. We identified 267 C2H2-ZF genes in B. napus and deciphered their physiological properties, subcellular localization, structure, synteny, and phylogeny and investigated the expression of 20 genes in response to different stresses and phytohormone treatments. The 267 genes were distributed on 19 chromosomes; phylogenetic analysis categorized them into five clades. They varied from 0.41 to 9.2 kb in length, had stress-responsive cis-acting elements in promoter regions, and their protein length varied from 9 to 1366 amino acids. About 42% of the genes had one exon, and 88% genes had orthologs in Arabidopsis thaliana. About 97% of the genes were located in nucleus and 3% in cytoplasmic organelles. qRT-PCR analysis showed a different expression pattern of these genes in response to biotic stresses (Plasmodiophora brassicae and Sclerotinia sclerotiorum) and abiotic stresses (cold, drought, and salinity) and hormonal treatments. Differential expression of the same gene was observed under multiple stress conditions, and a few genes showed similar expression in response to more than one phytohormones. Our results suggest that the C2H2-ZF genes can be targeted for the improvement of stress tolerance in canola.

All the 36 known species to date of the genus Aeromonas are mesophilic except the species Aeromonas salmonicida, which includes both psychrophilic and mesophilic subspecies. For 20 years, more and more mesophilic A. salmonicida strains have been discovered. Only A. salmonicida subsp. pectinolytica has officially been classified as a mesophilic subspecies. Most mesophiles have been isolated in hot countries. We present, for the first time, the characterization of two new mesophilic isolates from Quebec (Canada). Phenotypic and genomic characterizations were carried out on these strains, isolated from dead fish from a fish farm. Isolates 19-K304 and 19-K308 are clearly mesophiles, virulent to the amoeba Dictyostelium discoideum, a surrogate host, and close to strain Y577, isolated in India. To our knowledge, this is the first time that mesophilic strains isolated from different countries are so similar. The major difference between the isolates is the presence of plasmid pY47-3, a cryptic plasmid that sometimes presents in mesophilic strains. More importantly, our extensive phylogenetic analysis reveals two well-defined clades of mesophilic strains with psychrophiles associated with one of these clades. This helps to have a better understanding of the evolution of this species and the apparition of psychrophilic subspecies.

Polygonatum cyrtonema Hua is a traditional Chinese herb medicine, and it is widely distributed in China. The intrageneric taxonomy and phylogenetic relationships within Polygonatum have long been controversial due to their morphological similarity and lacking special DNA barcodes. In this paper, the complete chloroplast genome is a relatively conserved quadripartite structure including a large single copy region of 84 711 bp, a small single copy region of 18 210 bp, and a pair of inverted repeats region of 26 142 bp. A total of 342 simple sequence repeats were identified, and most of them were found to be composed of A/T, including 126 mono-nucleotides and 179 di-nucleotides. Nucleotide diversity was analyzed and eight highly variable regions (psbl∼trnT-CGU, atpF∼atpH, trnT-GGU∼psbD, psaJ∼rps20, trnL-UAG∼ndhD, ndhG∼ndhl, ndhA, and rpl32∼ccsA) were identified as potential molecular markers. Phylogenetic analysis based on the whole chloroplast genome showed that P. cyrtonema, within the family Asparagaceae, is closely related to Polygonatum sibiricum and Polygonatum kingianum. The sequence matK, trnT-GGU & ccsA, and ndhG∼ndhA were identified as three DNA barcodes. The assembly and comparative analysis of P. cyrtonema complete chloroplast genome will provide essential molecular information about the evolution and molecular biology for further study.

Fetal myogenesis represents a critical period of porcine skeletal muscle development and requires coordinated expression of thousands of genes. Epigenetic mechanisms, including DNA methylation, drive transcriptional regulation during development; however, these processes are understudied in developing porcine tissues. We performed bisulfite sequencing to assess DNA methylation in pig longissimus dorsi muscle at 41- and 70-days gestation (dg), as well as RNA- and small RNA-sequencing to identify coordinated changes in methylation and expression between myogenic stages. We identified 45 739 differentially methylated regions (DMRs) between stages, and the majority (N = 34 232) were hypomethylated at 70 versus 41 dg. Integration of methylation and transcriptomic data revealed strong associations between differential gene methylation and expression. Differential miRNA methylation was significantly negatively correlated with abundance, and dynamic expression of assayed miRNAs persisted postnatally. Motif analysis revealed significant enrichment of myogenic regulatory factor motifs among hypomethylated regions, suggesting that DNA hypomethylation may function to increase accessibility of muscle-specific transcription factors. We show that developmental DMRs are enriched for GWAS SNPs for muscle- and meat-related traits, demonstrating the potential for epigenetic processes to influence phenotypic diversity. Our results enhance understanding of DNA methylation dynamics of porcine myogenesis and reveal putative cis-regulatory elements governed by epigenetic processes.