Molecular subtyping of small-cell lung cancer based on mutational signatures with different genomic features and therapeutic strategies.

Small-cell lung cancer (SCLC) is an exceptionally lethal malignancy characterized by extremely high alteration rates and tumor heterogeneity, which limits therapeutic options. In contrast to non-small-cell lung cancer that develops rapidly with precision oncology, SCLC still remains outside the realm of precision medicine. No recurrent and actionable mutations have been detected. Additionally, a paucity of substantive tumor specimens has made it even more difficult to classify SCLC subtypes based on genetic background. We therefore carried out whole-exome sequencing (WES) on the largest available Chinese SCLC cohort. For the first time, we partitioned SCLC patients into three clusters with different genomic alteration profiles and clinical features based on their mutational signatures. We showed that these clusters presented differences in intratumor heterogeneity and genome instability. Moreover, a wide existence of mutually exclusive gene alterations, typically within similar biological functions, was detected and suggested a high SCLC intertumoral heterogeneity. Particularly, Cluster 1 presented the greatest potential to benefit from immunotherapy, and Cluster 3 constituted recalcitrant SCLC, warranting biomarker-directed drug development and targeted therapies in clinical trials. Our study would provide an in-depth insight into the genome characteristics of the Chinese SCLC cohort, defining distinct molecular subtypes as well as subtype-specific therapies and biomarkers. We propose tailoring differentiated therapies for distinct molecular subgroups, centering on a personalized precision chemotherapy strategy combined with immunization or targeted therapy for patients with SCLC.

Transcriptomic profiling reveals MEP pathway contributing to ginsenoside biosynthesis in Panax ginseng.

BACKGROUND: Panax ginseng C. A. Mey is one of famous medicinal herb plant species. Its major bioactive compounds are various ginsenosides in roots and rhizomes. It is commonly accepted that ginsenosides are synthesized from terpene precursors, IPP and DMAPP, through the cytoplasmic mevalonate (MVA) pathway. Another plastic 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway was proved also contributing to ginsenoside generation in the roots of P. ginseng by using specific chemical inhibitors recently. But their gene expression characteristics are still under reveal in P. ginseng. With the development of the high-throughput next generation sequencing (NGS) technologies, we have opportunities to discover more about the complex ginsenoside biosynthesis pathways in P. ginseng. RESULTS: We carried out deep RNA sequencing and comprehensive analyses on the ginseng root samples of 1-5 years old and five different tissues of 5 years old ginseng plants. The de novo assembly totally generated 48,165 unigenes, including 380 genes related to ginsenoside biosynthesis and all the genes encoding the enzymes of the MEP pathway and the MVA pathway. We further illustrated the gene expression profiles related to ginsenoside biosynthesis among 1-5 year-old roots and different tissues of 5 year-old ginseng plants. Particularly for the first time, we revealed that the gene transcript abundances of the MEP pathway were similar to those of the MVA pathway in ginseng roots but higher in ginseng leaves. The IspD was predicated to be the rate-limiting enzyme in the MEP pathway through both co-expression network and gene expression profile analyses. CONCLUSIONS: At the transcriptional level, the MEP pathway has similar contribution to ginsenoside biosynthesis in ginseng roots, but much higher in ginseng leaves, compared with the MVA pathway. The IspD might be the key enzyme for ginsenoside generation through the MEP pathway. These results provide new information for further synthetic biology study on ginsenoside metabolic regulation.

Insights into the Evolution of Hydroxyproline-Rich Glycoproteins from 1000 Plant Transcriptomes.

The carbohydrate-rich cell walls of land plants and algae have been the focus of much interest given the value of cell wall-based products to our current and future economies. Hydroxyproline-rich glycoproteins (HRGPs), a major group of wall glycoproteins, play important roles in plant growth and development, yet little is known about how they have evolved in parallel with the polysaccharide components of walls. We investigate the origins and evolution of the HRGP superfamily, which is commonly divided into three major multigene families: the arabinogalactan proteins (AGPs), extensins (EXTs), and proline-rich proteins. Using motif and amino acid bias, a newly developed bioinformatics pipeline, we identified HRGPs in sequences from the 1000 Plants transcriptome project (www.onekp.com). Our analyses provide new insights into the evolution of HRGPs across major evolutionary milestones, including the transition to land and the early radiation of angiosperms. Significantly, data mining reveals the origin of glycosylphosphatidylinositol (GPI)-anchored AGPs in green algae and a 3- to 4-fold increase in GPI-AGPs in liverworts and mosses. The first detection of cross-linking (CL)-EXTs is observed in bryophytes, which suggests that CL-EXTs arose though the juxtaposition of preexisting SPn EXT glycomotifs with refined Y-based motifs. We also detected the loss of CL-EXT in a few lineages, including the grass family (Poaceae), that have a cell wall composition distinct from other monocots and eudicots. A key challenge in HRGP research is tracking individual HRGPs throughout evolution. Using the 1000 Plants output, we were able to find putative orthologs of Arabidopsis pollen-specific GPI-AGPs in basal eudicots.

Co-cultivation of Chlamydomonas reinhardtii with Azotobacter chroococcum improved H2 production.

OBJECTIVES: To improve H2 production, the green algae Chlamydomonas reinhardtii cc849 was co-cultured with Azotobacter chroococcum. RESULTS: The maximum H2 production of the co-culture was 350% greater than that of the pure algal cultures under optimal H2 production conditions. The maximum growth and the respiratory rate of the co-cultures were about 320 and 300% of the controls, and the dissolved O2 of co-cultures was decreased 74%. Furthermore, the in vitro maximum hydrogenase activity of the co-culture was 250% greater than that of the control, and the in vivo maximum hydrogenase activity of the co-culture was 1.4-fold greater than that of the control. In addition, the maximum starch content of co-culture was 1400% that of the control. CONCLUSIONS: Azotobacter chroococcum improved the H2 production of the co-cultures by decreasing the O2 content and increasing the growth and starch content of the algae and the hydrogenase activity of the co-cultures relative to those of pure algal cultures.

Plasma cell-free DNA 5-hydroxymethylcytosine and whole-genome sequencing signatures for early detection of esophageal cancer.

Esophageal cancer is a highly incidence and deadly disease with a poor prognosis, especially in developing countries. Owing to the lack of specific symptoms and early diagnostic biomarkers, most patients are diagnosed with advanced disease, leading to a 5-year survival rate of less than 15%. Early (n = 50) and middle-advanced (n = 50) esophageal squamous cell carcinoma (ESCC) patients, as well as 71 healthy individuals, underwent 5-hydroxymethylcytosine (5hmC) sequencing on their plasma cell-free DNA (cfDNA). A Northern Chinese cohort of cfDNA 5hmC dataset of 150 ESCC patients and 183 healthy individuals were downloaded for validation. A diagnostic model was developed using cfDNA 5hmC signatures and then improved by low-pass whole genome sequencing (WGS) features of cfDNA. Conserved cfDNA 5hmC modification motifs were observed in the two independent ESCC cohorts. The diagnostic model with 5hmC features achieved an AUC of 0.810 and 0.862 in the Southern and Northern cohorts, respectively, with sensitivities of 69.3-74.3% and specificities of 82.4-90.7%. The performance was well maintained in Stage I to Stage IV, with accuracy of 70-100%, but low in Stage 0, 33.3%. Low-pass WGS of cfDNA improved the AUC to 0.934 with a sensitivity of 82.4%, a specificity of 88.2%, and an accuracy of 84.3%, particularly significantly in Stage 0, with an accuracy up to 80%. 5hmC and WGS could efficiently differentiate very early ESCC from healthy individuals. These findings imply a non-invasive and convenient method for ESCC detection when clinical treatments are available and may eventually prolong survival.

Whole exome sequencing in Chinese mucinous pulmonary adenocarcinoma uncovers specific genetic variations different from lung adenocarcinoma.

Background: As a rare subtype of primary lung adenocarcinoma (LUAD), mucinous pulmonary adenocarcinoma (MPA) was considered a distinctive entity with unfavorable outcomes. Therefore, there is a great need for a better understanding of the genomic and immunological landscape of this rare tumor type, which would inform improved therapeutic strategies. Methods: A total of 96 patients histologically confirmed with MPA were recruited from Shandong Cancer Hospital and Institute (SCH). Single nucleotide variation (SNV), copy number variation (CNV), genomic instability, and immunological landscape insights into 96 MPA patients were identified using WES. Results: We demonstrated that MPAs had marked different genomic alterations and were more complex in genomic profiles than LUADs. Mutations in Tumor Protein 53 (TP53) and CYP7A Promoter-Binding Factor (CPF) pathways significantly shortened survival whereas mutations in Notch and Wnt pathways significantly prolonged survival in MPA. Besides, we demonstrated that mutations in immune-related genes influenced outcomes, with mutations in TP53, Ataxia Telangiectasia Mutated (ATM), Polymerase (DNA) Delta 1 (POLD1), and Epidermal Growth Factor Receptor (EGFR) correlated with worsened survival. Conclusions: We not only depicted the genetic and immunologic landscape of Chinese MPA but also reveal its distinction from LUAD in genomic and immune context. Our findings may provide opportunities for therapeutic susceptibility among Chinese MPA patients.

Spatiotemporal genomic analysis reveals distinct molecular features in recurrent stage I non-small cell lung cancers.

Stage I non-small cell lung cancer (NSCLC) presents diverse outcomes. To identify molecular features leading to tumor recurrence in early-stage NSCLC, we perform multiregional whole-exome sequencing (WES), RNA sequencing, and plasma-targeted circulating tumor DNA (ctDNA) detection analysis between recurrent and recurrent-free stage I NSCLC patients (CHN-P cohort) who had undergone R0 resection with a median 5-year follow-up time. Integrated analysis indicates that the multidimensional clinical and genomic model can stratify the prognosis of stage I NSCLC in both CHN-P and EUR-T cohorts and correlates with positive pre-surgical deep next generation sequencing (NGS) ctDNA detection. Increased genomic instability related to DNA interstrand crosslinks and double-strand break repair processes is significantly associated with early tumor relapse. This study reveals important molecular insights into stage I NSCLC and may inform clinical postoperative treatment and follow-up strategies.

Identification of a Novel SLC8A1-ALK Fusion and Non-Canonical Expression Significantly Responding to ALK-TKIs in Lung Adenocarcinoma: A Case Report.

BACKGROUND: Approximately 2-7% of patients with non-small cell lung cancer harbor anaplastic lymphoma kinase (ALK) rearrangement events. Of note, typical ALK actionable rearrangements are sensitive to treatment with tyrosine kinase inhibitors (TKIs). However, different types of ALK fusion influence the clinical outcomes of this therapeutic approach. Approximately 10-40% of patients with ALK-fusion positive non-small cell lung cancer do not response to ALK-TKI therapy. Therefore, it is important to accurately identify the types of ALK rearrangement for appropriate selection of clinical treatment. CASE REPORT: Using a DNA-targeted next-generation sequencing technique, we found a novel solute carrier family 8 member A1 (SLC8A1)-ALK fusion type in a patient with lung adenocarcinoma. Further reverse transcriptase-polymerase chain reaction and Sanger sequencing demonstrated the rearrangement as a B-cell CLL/lymphoma 11A (BCL11A)-ALK fusion at the transcriptional level. The patient showed a rapid and strong response to treatment with crizotinib, which lasted for 9 months. The patient also responded well to treatment with alectinib after developed resistance to crizotinib. CONCLUSION: A strategy combining DNA-targeted next-generation sequencing with RNA reverse transcriptase-polymerase chain reaction and sequencing, besides fluorescence in situ hybridization and immunohistochemistry, may provide an effective and practical solution for correct identification of partner genes and fusion structures in the diagnosis of ALK rearrangements, particularly for non-canonical expression patterns of ALK fusion events. The combined approach may lead to more benefits for patients.

Whole-Exome Sequencing on Circulating Tumor Cells Explores Platinum-Drug Resistance Mutations in Advanced Non-small Cell Lung Cancer.

Circulating tumor cells (CTCs) have important applications in clinical practice on early tumor diagnosis, prognostic prediction, and treatment evaluation. Platinum-based chemotherapy is a fundamental treatment for non-small cell lung cancer (NSCLC) patients who are not suitable for targeted drug therapies. However, most patients progressed after a period of treatment. Therefore, revealing the genetic information contributing to drug resistance and tumor metastasis in CTCs is valuable for treatment adjustment. In this study, we enrolled nine NSCLC patients with platinum-based chemotherapy resistance. For each patient, 10 CTCs were isolated when progression occurred to perform single cell-level whole-exome sequencing (WES). Meanwhile the patients' paired primary-diagnosed formalin-fixed and paraffin-embedded samples and progressive biopsy specimens were also selected to perform WES. Comparisons of distinct mutation profiles between primary and progressive specimens as well as CTCs reflected different evolutionary mechanisms between CTC and lymph node metastasis, embodied in a higher proportion of mutations in CTCs shared with paired progressive lung tumor and hydrothorax specimens (4.4-33.3%) than with progressive lymphatic node samples (0.6-11.8%). Functional annotation showed that CTCs not only harbored cancer-driver gene mutations, including frequent mutations of EGFR and TP53 shared with primary and/or progressive tumors, but also particularly harbored cell cycle-regulated or stem cell-related gene mutations, including SHKBP1, NUMA1, ZNF143, MUC16, ORC1, PON1, PELP1, etc., most of which derived from primary tumor samples and played crucial roles in chemo-drug resistance and metastasis for NSCLCs. Thus, detection of genetic information in CTCs is a feasible strategy for studying drug resistance and discovering new drug targets when progressive tumor specimens were unavailable.

5-Hydroxymethylcytosine signature in circulating cell-free DNA as a potential diagnostic factor for early-stage colorectal cancer and precancerous adenoma.

Approximately 85% colorectal cancers (CRCs) are thought to evolve through the adenoma-to-carcinoma sequence associated with specific molecular alterations, including the 5-hydroxymethylcytosine (5hmC) signature in circulating cell-free DNA (cfDNA). To explore colorectal disease progression and evaluate the use of cfDNA as a potential diagnostic factor for CRC screening, here, we performed genome-wide 5hmC profiling in plasma cfDNA and tissue genomic DNA (gDNA) acquired from 101 samples (63 plasma and 38 tissues), collected from 21 early-stage CRC patients, 21 AD patients, and 21 healthy controls (HC). The gDNA and cfDNA 5hmC signatures identified in gene bodies and promoter regions in CRC and AD groups were compared with those in HC group. All the differential 5hmC-modified regions (DhMRs) were gathered into four clusters: Disease-enriched, AD-enriched, Disease-lost, and AD-lost, with no overlap. AD-related clusters, AD-enriched and AD-lost, displayed the unique 5hmC signals in AD patients. Disease-enriched and Disease-lost clusters indicated the general 5hmC changes when colorectal lesions occurred. Cancer patients with a confirmable adenoma history segmentally gathered in AD-enriched clusters. KEGG functional enrichment and GO analyses determined distinct differential 5hmC-modified profiles in cfDNA of HC individuals, AD, and CRC patients. All patients had comprehensive 5hmC signatures where Disease-enriched and Disease-lost DhMR clusters demonstrated similar epigenetic modifications, while AD-enriched and AD-lost DhMR clusters indicated complicated subpopulations in adenoma. Analysis of CRC patients with adenoma history showed exclusive 5hmC-gain characteristics, consistent with the 'parallel' evolution hypothesis in adenoma, either developed through the adenoma-to-carcinoma sequence or not. These findings deepen our understanding of colorectal disease and suggest that the 5hmC modifications of different pathological subtypes (cancer patients with or without adenoma history) could be used to screen early-stage CRC and assess adenoma malignancy with large-scale follow-up studies in the future.

Molecular cloning and characterization of maltooligosyltrehalose synthase gene from Nostoc flagelliforme.

A genomic DNA fragment encoding a putative maltooligosyltrehalose synthase (NfMTS) for trehalose biosynthesis was cloned by the degenerate primer-PCR from cyanobacterium Nostoc flagelliforme. The ORF of NfMTS was 2,799 bp in length and encoded 933 amino acid residues constituting a 106.6 kDa protein. The deduced amino acid sequence of NfMTS contained 4 regions highly conserved for MTSs. By expression of NfMTS in E. coli, it was demonstrated that the recombinant protein catalyzed the conversion of maltohexaose to maltooligosyl trehalose. The K(m) of the recombinant enzyme for maltohexaose was 1.87 mM and the optimal temperature and pH of the recombinant enzyme was at 50 degrees C and 7.0, respectively. The expression of MTS of N. flagelliforme was upregulated, and both trehalose and sucrose contents increased significantly in N. flagelliforme during drought stress. However, trehalose accumulated in small quantities (about 0.36 mg/g DW), whereas sucrose accumulated in high quantities (about 0.90 mg/g DW), indicating both trehalose and sucrose were involved in dehydration stress response in N. flagelliforme and sucrose might act as a chemical chaperone rather than trehalose did during dehydration stress.

Tracking Neoantigens by Personalized Circulating Tumor DNA Sequencing during Checkpoint Blockade Immunotherapy in Non-Small Cell Lung Cancer.

The evolutionary dynamics of tumor-associated neoantigens carry information about drug sensitivity and resistance to the immune checkpoint blockade (ICB). However, the spectrum of somatic mutations is highly heterogeneous among patients, making it difficult to track neoantigens by circulating tumor DNA (ctDNA) sequencing using "one size fits all" commercial gene panels. Thus, individually customized panels (ICPs) are needed to track neoantigen evolution comprehensively during ICB treatment. Dominant neoantigens are predicted from whole exome sequencing data for treatment-naïve tumor tissues. Panels targeting predicted neoantigens are used for personalized ctDNA sequencing. Analyzing ten patients with non-small cell lung cancer, ICPs are effective for tracking most predicted dominant neoantigens (80-100%) in serial peripheral blood samples, and to detect substantially more genes (18-30) than the capacity of current commercial gene panels. A more than 50% decrease in ctDNA concentration after eight weeks of ICB administration is associated with favorable progression-free survival. Furthermore, at the individual level, the magnitude of the early ctDNA response is correlated with the subsequent change in tumor burden. The application of ICP-based ctDNA sequencing is expected to improve the understanding of ICB-driven tumor evolution and to provide personalized management strategies that optimize the clinical benefits of immunotherapies.

Tauroursodeoxycholic acid (TUDCA) inhibits influenza A viral infection by disrupting viral proton channel M2.

Influenza is a persistent threat to human health and there is a continuing requirement for updating anti-influenza strategies. Initiated by observations of different endoplasmic reticulum (ER) responses of host to seasonal H1N1 and highly pathogenic avian influenza (HPAI) A H5N1 infections, we identified an alternative antiviral role of tauroursodeoxycholic acid (TUDCA), a clinically available ER stress inhibitor, both in vitro and in vivo. Rather than modulating ER stress in host cells, TUDCA abolished the proton conductivity of viral M2 by disrupting its oligomeric states, which induces inefficient viral infection. We also showed that M2 penetrated cells, whose intracellular uptake depended on its proton channel activity, an effect observed in both TUDCA and M2 inhibitor amantadine. The identification and application of TUDCA as an inhibitor of M2 proton channel will expand our understanding of IAV biology and complement current anti-IAV arsenals.

Access to RNA-sequencing data from 1,173 plant species: The 1000 Plant transcriptomes initiative (1KP).

BACKGROUND: The 1000 Plant transcriptomes initiative (1KP) explored genetic diversity by sequencing RNA from 1,342 samples representing 1,173 species of green plants (Viridiplantae). FINDINGS: This data release accompanies the initiative's final/capstone publication on a set of 3 analyses inferring species trees, whole genome duplications, and gene family expansions. These and previous analyses are based on de novo transcriptome assemblies and related gene predictions. Here, we assess their data and assembly qualities and explain how we detected potential contaminations. CONCLUSIONS: These data will be useful to plant and/or evolutionary scientists with interests in particular gene families, either across the green plant tree of life or in more focused lineages.

High yield production of salidroside in the suspension culture of Rhodiola sachalinensis.

Salidroside has been identified as the most potent ingredient of the Chinese medicine herb, Rhodiola sachalinensis. Since the natural supply of this herb is rapidly decreasing, we established a compact callus aggregate (CCA) strain and culturing system for high yield salidroside production. Several callus strains induced from the explants originated from root, stem, leaf and cotyledon of R. sachalinensis were established and screened for rapid growth rate, high salidroside content and easy propagation in suspension culture condition. The CCA strain was established from a callus strain initiated from the cotyledon. The kinetics of dry weight accumulation and cellular salidroside content in various culture conditions for the strain was determined. For high salidroside production, the optimal inoculum amount was 10% and the optimal concentration for 6-benzylaminopurine and indole-3-butyric acid added in the liquid medium was 5 and 2.5 mg l-1, respectively. The acidic culture medium and a faster shaking speed favored the salidroside accumulation. The addition of 2,4-D, in the liquid MS medium and the utilization of L-tyrosol for chemical feeding enhanced salidroside production. Using a proper combination of culture condition and treatment, salidroside accumulation could reach 57.72 mg g-1 dry weight, that was 5-10-fold higher than that detected in field-grown plants. The corresponding salidroside yield was 555.13 mg l-1, a level suitable for cost effective commercial production to compensate the natural resource shortage of R. sachalinensis.

Phylogeny of C4-photosynthesis enzymes based on algal transcriptomic and genomic data supports an archaeal/proteobacterial origin and multiple duplication for most C4-related genes.

Both Calvin-Benson-Bassham (C3) and Hatch-Slack (C4) cycles are most important autotrophic CO2 fixation pathways on today's Earth. C3 cycle is believed to be originated from cyanobacterial endosymbiosis. However, studies on evolution of different biochemical variants of C4 photosynthesis are limited to tracheophytes and origins of C4-cycle genes are not clear till now. Our comprehensive analyses on bioinformatics and phylogenetics of novel transcriptomic sequencing data of 21 rhodophytes and 19 Phaeophyceae marine species and public genomic data of more algae, tracheophytes, cyanobacteria, proteobacteria and archaea revealed the origin and evolution of C4 cycle-related genes. Almost all of C4-related genes were annotated in extensive algal lineages with proteobacterial or archaeal origins, except for phosphoenolpyruvate carboxykinase (PCK) and aspartate aminotransferase (AST) with both cyanobacterial and archaeal/proteobacterial origin. Notably, cyanobacteria may not possess complete C4 pathway because of the flawed annotation of pyruvate orthophosphate dikinase (PPDK) genes in public data. Most C4 cycle-related genes endured duplication and gave rise to functional differentiation and adaptation in different algal lineages. C4-related genes of NAD-ME (NAD-malic enzyme) and PCK subtypes exist in most algae and may be primitive ones, while NADP-ME (NADP-malic enzyme) subtype genes might evolve from NAD-ME subtype by gene duplication in chlorophytes and tracheophytes.

Genome sequence and genetic diversity of the common carp, Cyprinus carpio.

The common carp, Cyprinus carpio, is one of the most important cyprinid species and globally accounts for 10% of freshwater aquaculture production. Here we present a draft genome of domesticated C. carpio (strain Songpu), whose current assembly contains 52,610 protein-coding genes and approximately 92.3% coverage of its paleotetraploidized genome (2n = 100). The latest round of whole-genome duplication has been estimated to have occurred approximately 8.2 million years ago. Genome resequencing of 33 representative individuals from worldwide populations demonstrates a single origin for C. carpio in 2 subspecies (C. carpio Haematopterus and C. carpio carpio). Integrative genomic and transcriptomic analyses were used to identify loci potentially associated with traits including scaling patterns and skin color. In combination with the high-resolution genetic map, the draft genome paves the way for better molecular studies and improved genome-assisted breeding of C. carpio and other closely related species.

A pyrosequencing-based metagenomic study of methane-producing microbial community in solid-state biogas reactor.

BACKGROUND: A solid-state anaerobic digestion method is used to produce biogas from various solid wastes in China but the efficiency of methane production requires constant improvement. The diversity and abundance of relevant microorganisms play important roles in methanogenesis of biomass. The next-generation high-throughput pyrosequencing platform (Roche/454 GS FLX Titanium) provides a powerful tool for the discovery of novel microbes within the biogas-generating microbial communities. RESULTS: To improve the power of our metagenomic analysis, we first evaluated five different protocols for extracting total DNA from biogas-producing mesophilic solid-state fermentation materials and then chose two high-quality protocols for a full-scale analysis. The characterization of both sequencing reads and assembled contigs revealed that the most prevalent microbes of the fermentation materials are derived from Clostridiales (Firmicutes), which contribute to degrading both protein and cellulose. Other important bacterial species for decomposing fat and carbohydrate are Bacilli, Gammaproteobacteria, and Bacteroidetes (belonging to Firmicutes, Proteobacteria, and Bacteroidetes, respectively). The dominant bacterial species are from six genera: Clostridium, Aminobacterium, Psychrobacter, Anaerococcus, Syntrophomonas, and Bacteroides. Among them, abundant Psychrobacter species, which produce low temperature-adaptive lipases, and Anaerococcus species, which have weak fermentation capabilities, were identified for the first time in biogas fermentation. Archaea, represented by genera Methanosarcina, Methanosaeta and Methanoculleus of Euryarchaeota, constitute only a small fraction of the entire microbial community. The most abundant archaeal species include Methanosarcina barkeri fusaro, Methanoculleus marisnigri JR1, and Methanosaeta theromphila, and all are involved in both acetotrophic and hydrogenotrophic methanogenesis. CONCLUSIONS: The identification of new bacterial genera and species involved in biogas production provides insights into novel designs of solid-state fermentation under mesophilic or low-temperature conditions.

Systematic analysis of intron size and abundance parameters in diverse lineages.

All eukaryotic genomes have genes with introns in variable sizes. As far as spliceosomal introns are concerned, there are at least three basic parameters to stratify introns across diverse eukaryotic taxa: size, number, and sequence context. The number parameter is highly variable in lower eukaryotes, especially among protozoan and fungal species, which ranges from less than 4% to 78% of the genes. Over greater evolutionary time scales, the number parameter undoubtedly increases as observed in higher plants and higher vertebrates, reaching greater than 12.5 exons per gene in average among mammalian genomes. The size parameter is more complex, where multiple modes appear at work. Aside from intronless genes, there are three other types of intron-containing genes: half-sized, minimal, and size-expandable introns. The half-sized introns have only been found in a limited number of genomes among protozoan and fungal lineages and the other two types are prevalent in all animal and plant genomes. Among the size-expandable introns, the sizes of plant introns are expansion-limited in that the large introns exceeding 1000 bp are fewer in numbers and transposon-free as compared to the large introns among animals, where the larger introns are filled with transposable elements and appear expansion-flexible, reaching several kilobasepairs (kbp) and even thousands of kbp in size. Most of the intron parameters can be studied as signatures of the specific splicing machineries of different eukaryotic lineages and are highly relevant to the regulation of gene expression and functionality. In particular, the transcription-splicing-export coupling of eukaryotic intron dispensing leads to a working hypothesis that all intron parameters are evolved to be efficient and function-related in processing and routing the spliced transcripts.