Using next-generation sequencing technology alone, we have successfully generated and assembled a draft sequence of the giant panda genome. The assembled contigs (2.25 gigabases (Gb)) cover approximately 94% of the whole genome, and the remaining gaps (0.05 Gb) seem to contain carnivore-specific repeats and tandem repeats. Comparisons with the dog and human showed that the panda genome has a lower divergence rate. The assessment of panda genes potentially underlying some of its unique traits indicated that its bamboo diet might be more dependent on its gut microbiome than its own genetic composition. We also identified more than 2.7 million heterozygous single nucleotide polymorphisms in the diploid genome. Our data and analyses provide a foundation for promoting mammalian genetic research, and demonstrate the feasibility for using next-generation sequencing technologies for accurate, cost-effective and rapid de novo assembly of large eukaryotic genomes.

Abstract:Exosomes are small membrane-bound vesicles secreted by most cell types. Exosomes contain various functional proteins, mRNAs and microRNAs (miRNAs) that could be used for diagnostic and therapeutic purposes. How we should store the samples before RNA isolation and whether those long term stored samples could be used for circulating RNA investigation because of RNase is unknown. The aim of the study was to determine the stability of circulating miRNA in exosomes and plasma. Exosomes were isolated from plasma samples by using ExoQuick Precipitation methods. RNA was extracted from exosomes and the corresponding plasma samples with a Qiagen miRNeasy Mini kit. The concentration of RNA was measured by a Qubit ® RNA HS Assay Kit, and quantitative PCR was used for individual miRNA expression level detection. Results showed that exosomal miRNA showed extra stability under different storage conditions and no significant influence on plasma miRNA, except for short term storage at 4 °C. It is thus indicated that exosome miRNAs can be good biomarkers based on their stability under various storage conditions.

Modular protein domains are functional units that can be modified through the acquisition of new intrinsic activities or by the formation of novel domain combinations, thereby contributing to the evolution of proteins with new biological properties. Here, we assign proteins to groups with related domain compositions and functional properties, termed "domain clubs," which we use to compare multiple eukaryotic proteomes. This analysis shows that different domain types can take distinct evolutionary trajectories, which correlate with the conservation, gain, expansion, or decay of particular biological processes. Evolutionary jumps are associated with a domain that coordinately acquires a new intrinsic function and enters new domain clubs, thereby providing the modified domain with access to a new cellular microenvironment. We also coordinately analyzed the covalent and noncovalent interactions of different domain types to assess the molecular compartment occupied by each domain. This reveals that specific subsets of domains demarcate particular cellular processes, such as growth factor signaling, chromatin remodeling, apoptotic and inflammatory responses, or vesicular trafficking. We suggest that domains, and the proteins in which they reside, are selected during evolution through reciprocal interactions with protein domains in their local microenvironment. Based on this scheme, we propose a mechanism by which Tudor domains may have evolved to support different modes of epigenetic regulation and suggest a role for the germline group of mammalian Tudor domains in Piwi-regulated RNA biology.

Recent studies have suggested that the secondary structure of the 5 ′ untranslated region (5 ′ UTR) of messenger RNA (mRNA) is important for microRNA (miRNA)-mediated gene regulation in humans. mRNAs that are targeted by miRNA tend to have a higher degree of local secondary structure in their 5 ′ UTR; however, the general role of the 5 ′ UTR in miRNA-mediated gene regulation remains unknown. We systematically surveyed the secondary structure of 5 ′ UTRs in both plant and animal species and found a universal trend of increased mRNA stability near the 5 ′ cap in mRNAs that are regulated by miRNA in animals, but not in plants. Intra-genome comparison showed that gene expression level, GC content of the 5 ′ UTR, number of miRNA target sites, and 5 ′ UTR length may influence mRNA structure near the 5 ′ cap. Our results suggest that the 5 ′ UTR secondary structure performs multiple functions in regulating post-transcriptional processes. Although the local structure immediately upstream of the start codon is involved in translation initiation, RNA structure near the 5 ′ cap site, rather than the structure of the full-length 5 ′ UTR sequences, plays an important role in miRNA-mediated gene regulation.

24Circular RNAs (circRNAs) are a novel class of regulatory RNAs. Here, we present a 25 comprehensive investigation of circRNA expression profiles across 11 tissues and 4 26 developmental stages in rats, along with cross-species analyses in humans and mice. Although 27 the expression of circRNAs is positively correlated with that of cognate mRNAs, highly 28 expressed genes tend to splice a larger fraction of circular transcripts. Moreover, circRNAs 29 exhibit higher tissue specificity than cognate mRNAs. Intriguingly, while we observed a 30 monotonic increase of circRNA abundance with age in the rat brain, we further discovered a 31 dynamic, age-dependent pattern of circRNA expression in the testes that is characterized by a 32 dramatic increase with advancing stages of sexual maturity and a decrease with aging. The age-33 sensitive testicular circRNAs are highly associated with spermatogenesis, independent of cognate 34 mRNA expression.

Synonymous codons are widely selected for various biological mechanisms in both prokaryotes and eukaryotes. Recent evidence suggests that microRNA (miRNA) function may affect synonymous codon choices near miRNA target sites. To better understand this, we perform genome-wide analysis on synonymous codon usage around miRNA target sites in four plant genomes. We observed a general trend of increased site accessibility around miRNA target sites in plants. Guanine-cytosine (GC)-poor codons are preferred in the flank region of miRNA target sites. Within-genome analyses show significant variation among miRNA targets in species. GC content of the target gene can partly explain the variation of site accessibility among miRNA targets. miRNA targets in GC-rich genes show stronger selection signals than those in GC-poor genes. Gene's codon usage bias and the conservation level of miRNA and its target also have some effects on site accessibility, but the expression level of miRNA or its target and the mechanism of miRNA activity do not contribute to site accessibility differences among miRNA targets. We suggest that synonymous codons near miRNA targets are selected for efficient miRNA binding and proper miRNA function. Our results present a new dimension of natural selection on synonymous codons near miRNA target sites in plants, which will have important implications of coding sequence evolution.

BackgroundCircular RNAs (circRNAs) are a class of novel RNAs with important biological functions, and aberrant expression of circRNAs has been implicated in human diseases. However, the feasibility of using blood circRNAs as disease biomarkers is largely unknown.MethodsWe explored the potential of using human peripheral blood mononuclear cell (PBMC) circRNAs as marker molecules to diagnose active pulmonary tuberculosis (TB).FindingsFirst, we demonstrated that circRNAs are widely expressed in human PBMCs and that many are abundant enough to be detected. Second, we found that the magnitude of PBMC circRNAs in TB patients was higher than that in the paired healthy controls. Compared with host linear transcripts, the circRNAs within several pathways are disproportionately upregulated in active TB patients, including “Cytokine-cytokine receptor interaction”, “Chemokine signaling pathway”, “Neurotrophin signaling pathway”, and “Bacterial invasion of epithelial cells”. Based on the differentially expressed circRNAs within these pathways, we developed a PBMC circRNA-based molecular signature differentiating active TB patients from healthy controls. We validated the classification power of the PBMC circRNA signature in an independent cohort with the area under the receiver operating characteristic curve (AUC) at 0.946.InterpretationOur results suggest that PBMC circRNAs are potentially reliable marker molecules in TB diagnosis.

Supplementary data are available at Bioinformatics online.